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Transient absorption (TA) spectroscopy of semiconductor nanocrystals (NCs) is often used for excited state population analysis, but recent results suggest that TA bleach signals associated with multiexcitons in NCs do not scale linearly with exciton multiplicity. In this manuscript, we probe the factors that determine the intensities and spectral positions of exciton and biexciton components in the TA spectra of CdSe quantum dots (QDs) of five diameters. We find that, in all cases, the peak intensity of the biexciton TA spectrum is less than 1.5 times that of the single exciton TA spectrum, in stark contrast to a commonly made assumption that this ratio is 2. The relative intensities of the biexciton and exciton TA signals at each wavelength are determined by at least two factors: the TA spectral intensity and the spectral offset between the two signals. We do not observe correlations between either of these factors and the particle diameter, but we find that both are strongly impacted by replacing the native organic surface-capping ligands with a hole-trapping ligand. These results suggest that surface trapping plays an important role in determining the absolute intensities of TA features for CdSe QDs and not just their decay kinetics. Our work highlights the role of spectral offsets and the importance of surface trapping in governing absolute TA intensities. It also conclusively demonstrates that the biexciton TA spectra of CdSe QDs at the band gap energy are less than twice as intense as those of the exciton. [ABSTRACT FROM AUTHOR]

Two new structure-specific scalar intensity measures for plane reinforced concrete moment resisting frames under far-fault ground motions are proposed. These intensity measures, of the spectral acceleration and spectral displacement type, are characterized as multi-modal and multi-level. They encompass the effects of the first four natural periods and are defined for four performance levels, including considerations of inelasticity up to the collapse prevention level. This is achieved with the aid of equivalent linear modal damping ratios previously developed by the authors for performance-based seismic design purposes. These modal damping ratios, dependent on period, soil type, and deformation, are associated with the transformation of the original multi-degree-of-freedom (MDOF) nonlinear structure into an equivalent MDOF linear one. The proposed intensity measures are conceptualized to be simple and elegant, incorporating all the aforementioned features rationally, without the artificial combination of terms, definition of period ranges, or addition of coefficients determined by optimization procedures. This approach sets it apart from existing measures that attempt to account for multiple modes and inelasticity. A comparison of the proposed intensity measures against ten of the most popular existing ones in the literature, focusing on efficiency, practicality, proficiency, scaling robustness and sufficiency, demonstrate their advantages. [ABSTRACT FROM AUTHOR]

The substitution of microbial fertilizer for chemical fertilizer can not only improve soil fertility but also effectively enhance rice quality. To investigate the effect of different amounts of combined application of chemical fertilizer and microbial fertilizer on the amylose content of rice, this study adopts theoretical calculations to compare the preprocessed Raman spectroscopy information of rice with reduced fertilization and establishes a recognition model for the amylose content of rice, which is used to detect the amylose content in rice. Based on the amylose spectral values measured by Raman spectroscopy and the known starch structure and functional groups, the Raman peaks are mainly distributed in the range of 400 cm− 1 to 1400 cm− 1. The Raman characteristic peaks at 483 cm− 1, 869 cm− 1, 933 cm− 1, 1082 cm− 1, 1126 cm− 1, 1335 cm− 1, 1385 cm− 1, and 1455 cm− 1 exhibit strong vibration modes, which are consistent with its main nutrient component of amylose. By comparing the measured amylose content in the regions treated with microbial fertilizer combined with different amounts of reduced fertilization and the spectral intensity values of amylose measured by Raman spectroscopy, the results show that the treatment of combining conventional amounts of microbial fertilizer with different amounts of reduced chemical fertilizer exhibits a decreasing trend in the amylose content of rice. [ABSTRACT FROM AUTHOR]

The identification of machining processes for low roughness samples is extremely challenging, and a reasonably quick identification of machining processes for low roughness parts is critical for ensuring that the samples are employed under the appropriate conditions and improving work efficiency. In this work, a new identification method of fusion of LIBS spectra and plasma acoustic emission signals (PAESs) with bimodal information is proposed, and the LIBS spectral data and PAES data of nine types of low roughness samples processed by three machining processes, namely horizontal milling, plain grinding, and vertical milling, are recorded and analyzed. The spectral intensities of the primary element Fe and trace element Mn are compared and analyzed. The spectrum intensities of the primary element Fe and trace element Mn, as well as the PAES maximum peak, are compared and examined. Using the PCA-SVM machine learning technique, the three recognition impacts of single LIBS data, single PAES data, and LIBS-PAES bimodal data fusion are examined and compared. At Ra = 0.4 μm and 0.8 μm, vertical milling produces significantly higher spectral intensities than plain grinding and horizontal milling, while horizontal milling produces significantly higher intensities than plain grinding. When the surface roughness of the samples is the same, variations in the machining process cause changes in the PAES. The recognition accuracy was 86.67% for the test set of single LIBS spectral data, 78.89% for the test set of single PAES data, and 97.11% for the training set, and 91.11% for the test set of LIBS-PAES bimodal data fusion, respectively. When compared to single-modal data recognition, bimodal data fusion greatly improves recognition ability, fully reflecting the benefits of bimodal data fusion. Based on the results of this study, it can be preliminarily concluded that the fusion of spectral and acoustic information in laser-induced breakdown spectroscopy detection is very promising for recognizing the surface state of parts in the machining field. [ABSTRACT FROM AUTHOR]

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This study aims to investigate the adverse effects of near-fault ground motions on the long-term development of high-speed railways. In this paper, the ground motions are analyzed based on the Train–Track–Bridge Coupling Braking System (TTBCBS) which has been validated during earthquakes. The effects of earthquakes on the whole system are discussed in depth, focusing on the random nature of earthquakes, the impulsive character of near-fault earthquakes and the effects of different initial speeds on the system behavior. The results show that under random earthquakes, the probability of train derailment gradually increases with the increase of peak ground acceleration (PGA) of earthquakes. When the PGA exceeds 0.2 g, the train is highly susceptible to derailment and the bridge itself may incur damage. When analyzing the nature of pulses of near-fault ground motions, it was found that the responses induced by class B and class C pulses are significantly similar. Meanwhile, the calculated values of derailment coefficients are basically the same when the PGA of class A pulse wave is at 0 g and 0.1 g. This suggests that train braking somewhat mitigates the response induced by near-fault ground motions. Furthermore, the value of improved spectral intensity (SI) for the running safety during earthquakes indicates that the increase in seismic intensity is detrimental to the system. In terms of the effect of train initial speeds on the system during earthquakes, it is observed that the system response reaches the lowest point when the train speed is 250 km/h, which is more favorable to the smooth deceleration of the train. When the train speed is 400 km/h, the system response reaches its maximum value. These research findings provide crucial insights and guidance for seismic safety design and management of high-speed railways. [ABSTRACT FROM AUTHOR]

Macro‐Raman mapping is an approach that is well suited to study the distribution of molecules over a surface of typically several cm2, such as the pigment distribution on a painting. During such an experiment, thousands Raman spectra are recorded in a predefined array of points. As there can be a huge difference in Raman sensitivity between different molecules, an alternative approach is proposed, where measurement times are adapted according to the quality of the Raman scatterer. Therefore, an iterative process is implemented, involving recording short accumulations, followed by a quick evaluation. As soon as the accumulated spectrum reaches a quality criterium, measurement of the next point is started, while in the other case further accumulations are added. The influence of using multiple accumulations opposite to a single measurement for a prolonged period has been assessed by comparing the overall measurement time and the spectral intensity of the main Raman band (520.5 cm−1) of silicon. Another prerequisite for this algorithm to be successful is the need for a quick and reliable evaluation of the spectral quality. This was examined by applying this function on the accumulations of Raman spectra of 49 paint samples from a colour chart. Finally, the variable‐accumulation algorithm is applied during a macro‐Raman mapping experiment of a watercolour painting on paper. Despite a significant gain in overall measuring time, this novel approach yields a qualitative data set that can be used for creating clear Raman maps, using different data processing methods. [ABSTRACT FROM AUTHOR]

The poor spectral stability of laser-induced breakdown spectroscopy (LIBS) seriously affects its analytical performance, which is a key obstacle to its further development. To overcome this challenge, an improved spectral standardization method based on plasma image-spectrum fusion (ISS-PISF) was proposed in this study. This method, for the first time, considers and quantifies the influence of plasma morphology on spectral intensity based on the line-integrated intensity formula of LIBS spectra. It recognizes that the spectral fluctuations mainly stem from variations in total number density, plasma temperature, electron number density, and plasma morphology. Therefore, ISS-PISF innovatively utilizes easily accessible features from plasma images and spectra to eliminate the influence of these four plasma parameters, thereby improving the spectral stability and analytical performance of LIBS. To validate the effectiveness of this method, the spectra of aluminum alloy samples obtained under complex detection conditions simulated by varying laser energy and defocusing amount were analyzed. After correction by ISS-PISF, the R2 for Mg I 516.73 nm, Mn II 294.92 nm, and Si I 288.16 nm improved to 0.990, 0.976, and 0.961, and the average RMSE of the validation set decreased by 46.154%, while the average STD of the validation set decreased by 37.405%. These experimental results indicate that this study provides a simple, effective, and physically supported spectral standardization method, which contributes to the further promotion and application of LIBS. [ABSTRACT FROM AUTHOR]

This study presents a novel simultaneous double-exposure contact mirror-based method for fabricating holographic multi-notch filters with dual operational central wavelengths. The proposed method leverages coupled wave theory, the geometric relationships of K-vectors, and a reflection-type recording setup, incorporating additional reflecting mirrors to guide the recording beams. To validate the approach, a holographic notch filter was fabricated using photopolymer recording materials, resulting in operational wavelengths of 531.13 nm and 633.01 nm. The measured diffraction efficiencies at these wavelengths were ηs = 52.35% and ηp = 52.45% for 531.13 nm, and ηs = 67.30% and ηp = 67.40% for 633.01 nm. The component's performance was analyzed using s- and p-polarized spectral transmission intensities at various reconstruction angles, revealing polarization-independent characteristics under normal incidence and polarization-dependent behavior under oblique incidence. The study also explored the relationships between recording parameters, such as incident angle, wavelength, emulsion expansion, and dispersion. The findings demonstrate that the first operational central wavelength is primarily influenced by the recording wavelength, while the second is primarily determined by the incident angle, covering a range from visible light to near-infrared. This method offers significant potential for cost-effective, mass-produced filters in optoelectronic applications. [ABSTRACT FROM AUTHOR]

Intumescent fireproof coatings protect steel structures and cables by forming a thick, fire-resistant layer under high temperatures. These coatings can deteriorate over time, impacting their fire resistance. Current testing methods are largely lab-based, lacking in-service evaluation platforms. Laser-Induced Breakdown Spectroscopy (LIBS) is emerging as a promising in situ detection technology but is influenced by low air pressure in high-altitude areas. This study investigates how air pressure affects LIBS signals in intumescent coatings on galvanized steel. Using pressures between 35 and 101 kPa, a linear model was developed to correlate laser pulses to ablation depth for characterizing coating thickness. Results show that spectral intensity decreases with lower air pressure. However, a strong linear relationship persists between laser pulses and ablation depth, with a fitting accuracy above 0.9. The coating thickness is identified by the number of laser pulses required to detect the Zn spectral line from the underlying galvanized steel. As air pressure decreases, the ablation depth increases. The study effectively models and corrects for air pressure effects on LIBS data, enabling its application for field detection of fireproof coatings. This advancement enhances the reliability of LIBS technology in assessing the fire performance of these materials, providing a reference for their in situ evaluation and ensuring better fire safety standards for building steel structures and cables. [ABSTRACT FROM AUTHOR]

This paper presents a simple method to transform two‐dimensional data sets into a format that can be easily processed into sound files. These files can be loaded into software wavetable synthesizers to create audible forms of data that can represent complex information. Some background about sonification will be discussed, and the simple method developed here will be applied to graphene optoelectronics. Some key illustrative examples will be used to demonstrate the method, including data sets from previous work on light emission from graphene field effect transistors. We use the sonification method to show how changes in observed phenomena (e.g., light emission intensity and spectral shape) result in changes of the resulting sound (such as the timbre). Demonstrations are included in video format to hear and illustrate the method and resulting effects. [ABSTRACT FROM AUTHOR]

Daylight influences more than just our vision; elements such as its intensity and spectral composition can significantly impact our circadian rhythms and, consequently, our overall well-being. In this study, we present an analysis of a classroom simulated in Dialux, involving a comprehensive examination of natural daylight through a specific type of glazing, assessing their photopic characteristics and their influence on the human circadian system in individuals aged 32 and 70 years. Our findings highlight that spectral data from daylight (D75, D65, and D50) and glazing transmittance can be easily used to evaluate the melanopic equivalent daylight illuminance (mel-EDI) in addition to standard photopic illuminance, applying a f ( M P ) G l a z i n g factor calculated from the spectral characteristics of both daylight and glazing transmittance. Our results provide new insights for users to more effectively assess daylighting quality and its implications within indoor environments. [ABSTRACT FROM AUTHOR]

Utilizing the two-dimensional (2D) nano-bands with graphene-like atom arrangement in the structure of the solar cells is of significant importance for the next generation of solar cells. In the present research, germanene (2D structure consisting of germanium atoms) was placed in ITO/germanene (1, 2, 3)/ MoS 2 (n)/a-SiGe: H (i)/c-Si (P)/Au heterojunction solar cell structures once as semiconductor layers with Al (germanene1), P (germanene2), and In (germanene3) dopant, separately. Then, the free-standing germanene was used as front contact in a structure consisting of germanene/ MoS 2 (n)/a-SiGe: H (i)/c-Si (P)/Au of the heterojunction cell. The impacts of different radiant intensities at 300 K temperature by the AM1.5 spectrum radiation were investigated using the AFORS-HET simulation tool. The highest efficiency was obtained in the presence of the germanene2 layer, which was 18.64%, 17.78%, and 19.56%, respectively, in 1 sun, 0.1 sun, and 100 sun radiant intensities. By applying the free-standing germanene in the structure of the proposed cell, the efficiency in radiant intensities of 1 sun, 0.1 sun, and 50 sun were 26.98%, 25.87%, and 27.99%, respectively. The results suggest that this 2D structure can improve the cell's output parameters, especially the efficiency, positively affecting the solar cell function due to its monoatomic thickness. Therefore, germanene can be an emerging competitor to other 2D structures used in the structure of solar cells. [ABSTRACT FROM AUTHOR]

The visible/near-infrared (Vis/NIR) spectroscopy technique is effective for fruit quality detection. The distinct spectral features can reflect the internal composition of fruits, while variations in external orientation may induce interference. Considering both external and internal factors, we improved the discrimination accuracy of pest-infested crabapples by compensating for variations in orientation and amplifying differences in spectral morphological features (SMFs). Firstly, spectral intensity variations caused by orientations and morphological differences caused by pest infestation were analyzed. Based on these differences, the global model was established to mitigate the external orientation influence. Subsequently, SMFs, derived from spectral peaks and troughs, were employed to amplify spectral features. Finally, with the supplementation using 1st deviation, SMFs improved the discrimination performance of the partial least square–linear discriminant analysis (PLS-LDA) model for pest infestation, yielding results of sensitivity, specificity, and accuracy as 95.14%, 96.32%, and 95.94%, respectively. Overall, compensating for external orientation variations and exploiting internal spectral features enhanced the detection accuracy of pest infestation, providing valuable insights for internal defect discrimination based on Vis/NIR spectroscopy. [ABSTRACT FROM AUTHOR]

In this paper, the laser and arc are shifted laterally to change the position and energy distribution of arc discharge, which provides a new idea and theoretical basis for solving the narrow gap welding defects of titanium alloy thick plate. In this study, the effect of transverse offset distance between laser and arc (DLAP) on the discharge characteristics of hybrid heat source coupling and the flow characteristics of molten pool was studied by using the welding method of plate surfacing. The dynamic behavior of the arc plasma, the molten pool, and the keyhole was monitored in real time, and the plasma spectral information was collected to analyze its energy distribution characteristics. The results show that under different DLAP conditions, the charged plasma of the hybrid heat source has two different states: strong coupling state and separation state. When DLAP = 2 mm, the plasma at the center of the keyhole has the strongest spectral intensity, the lowest electron temperature, and the highest electron density, which are 15174, 9546 K, and 1.88 × 1017/cm3, respectively. At this time, the weld pool and keyhole have the maximum arc pressure and Marangoni force, resulting in an increase in the flow velocity of the weld pool and an increase in the area of the weld pool. [ABSTRACT FROM AUTHOR]

As a modality of optical imaging, fluorescence imaging of biochemical analytes holds significant potential in the field of disease diagnosis and therapy. However, the non‐responsive fluorophores are not able to selectively and sensitively detect lesions, resulting in a poor signal‐to‐background ratio and compromised accuracy. The utilization of activatable sensors, in contrast, is capable of effectively overcoming these limitations by displaying variations in fluorescence intensity and spectral wavelength in response to physiological parameters. Aggregation‐induced emission luminogens (AIEgens), particularly those emitting fluorescence in the near‐infrared (NIR, 700–1700 nm) window, have practical application prospects in disease theranostics due to their excellent photostability, deeper penetration depth, and enhanced fluorescence intensity in physiological environments. In this review, an overview of the advancements in research on NIR AIEgens for internal stimuli‐activated diagnosis and treatment of diseases is provided. The design principles of responsive NIR AIEgens and their biomedical applications are exemplified with representative examples, categorized based on the type of stimuli. Finally, the review concludes with a brief discussion of the challenges, opportunities, and future prospects of activatable NIR AIEgens in the field of disease photo theranostics. [ABSTRACT FROM AUTHOR]

In this work, we demonstrate systematic studies on the influence of Fe 2 O 3 on the structural and optical properties of transparent B 2 O 3 –TeO 2 –Na 2 O glasses containing the different concentrations of Fe 2 O 3. The glasses were prepared via the standard melt quenching method, and the prepared glasses were characterized using, XRD, electron paramagnetic resonance (EPR), FTIR, and UV–visible spectroscopic techniques. Furthermore, we evaluated several physical properties of the glasses, including densities, molar volume, boron-boron separation, and oxygen packing density, with respect to the concentration of Fe 2 O 3 in the host glass matrix. It is observed that the density of the glasses and the average boron-boron distance found increase with Fe 2 O 3 concentration due to the modification in the glass network induced by the dopant ions. EPR spectra reveals the presence resonance signals at g ∼2.04 and g ∼4.26, hence it proves the existence of Fe3+ in distorted octahedral coordination and supported by UV–Vis absorption bands. The FTIR spectra revealed an increase in spectral intensity with the concentration of Fe 2 O 3. This was attributed to the formation of non-bridging oxygens through converting BO 4 units into BO 3 units, which Fe 2 O 3 mediated. The UV–visible spectral analysis showed a decreased energy band gap from 2.26 to 1.51 eV with increased Fe 2 O 3 concentration. Additionally, we determined the Urbach energy, refractive index, optical basicity, and electronegativity, which are presented in detail. [ABSTRACT FROM AUTHOR]

A ground-based 110 GHz radiometer was designed to measure the stratospheric ozone vertical profile by observing the 110.836 GHz ozone emission spectrum and the instrument has been operational at Sookmyung Women's University (37.54° N, 126.97° E) in Seoul, Korea. In this paper, we detail the instrumental design, calibration procedures, correction methods, and the retrieved ozone vertical profile. The instrument is a heterodyne total power radiometer. It down-converts the observed 110.836 GHz ozone frequency to 0.609 GHz, with a frequency resolution of 61 kHz and a bandwidth of 800 MHz. The spectral intensity is digitized using a fast Fourier transform spectrometer. For hot-cold calibration, we use microwave absorbers at room temperature and liquid nitrogen as calibration targets. Tropospheric opacity is corrected using the continuous tipping curve calibration. The measured opacities were compared with simulated values from the Korea Local Analysis and Prediction System (KLAPS) data. Additionally, since 2016, the stratospheric ozone profiles over Seoul have been demonstrated for the vertical range of 100 hPa – 0.3 hPa (16 km–70 km) with validation performed by comparing them to the ozone profiles from the MLS on AURA satellite. [ABSTRACT FROM AUTHOR]

The transmittance, reflectivity, and photoluminescence in the range 0.8–1.7 eV at 300 K and 77 K in the spectral range 0.6–6.0 eV at 300 K of thin films of CdTe synthesized on different substrates by thermal evaporation in a quasi-closed volume were studied. A strong dependence of the intensity and position of the band–band and excitonic luminescence bands on the substrate quality was discovered. The excitonic luminescence bands of films on silicon and glass were shifted by 10 meV to the short-wavelength region because of internal stresses in the films owing to the mismatch between the unit-cell parameters of the substrate and film. The transparency region of films cleaved from glass shifted to the longwavelength region because of the density tails of electronic states in the band gap caused by disordering of the films and the longer wavelength of the light than the roughness of the films on the growth and nucleation side. The best structural perfection was characteristic of films on a CdTe substrate based on the obtained dependences of the intensity and spectral position of the photoluminescence lines. [ABSTRACT FROM AUTHOR]

This review delves into the forefront of upconversion luminescence (UCL) research, focusing on KY3F10-based compounds, particularly their cubic α-phase. These materials are renowned for their exceptional luminescent properties and structural stability, making them prime candidates for advanced photonic applications. The synthesis methods and structural characteristics of the existing works in the literature are meticulously analyzed alongside the transformative effects of various doping strategies on UCL efficiency. Incorporating rare earth (RE) sensitizer ions such as Yb3+, along with activator ions like Er3+, Ho3+, Nd3+, or Tm3+, researchers have achieved remarkable enhancements in emission intensity and spectral control. Recent and past breakthroughs in understanding the local structure and phase transitions of single-, double-, and triple-RE3+-doped KY3F10 nanocrystals are highlighted, revealing their pivotal role in fine-tuning luminescent properties. Furthermore, the review underscores the untapped potential of lesser-known crystal structures, such as the metastable δ-phase of KY3F10, which offers promising avenues for future exploration. By presenting a comprehensive analysis and proposing innovative research directions, this review aims to inspire continued advancements in the field of upconversion materials, unlocking new potentials in photonic technologies. [ABSTRACT FROM AUTHOR]

In the present work we have modeled diffuse auroral emissions in Jupiter using the recent observations received by JUNO orbiter. Resonant wave‐particle interaction by electron‐cyclotron harmonic (ECH) waves has been invoked as the mechanism for production of diffuse aurora. Energetic electrons trapped on closed field lines are diffused into the loss‐cone via pitch‐angle diffusion. Electron precipitation fluxes have been calculated. Electrons entering into the atmosphere undergo collisions with atmospheric constituents atomic H and molecular H2 producing electromagnetic emissions. Four excitations have been considered. These excitations are: HLy‐α from excitation of atomic H, HLy‐α from dissociative excitation of molecular H2, Lyman and Werner bands of H2. Volume excitation rates have been calculated for these excitations. Height integrated volume excitation rates have been obtained to give auroral intensities. Numerical calculations have been performed at five L‐shells; L = 10, 12, 15, 18 and 20. Maximum auroral intensities is obtained at shell L = 10. At higher shell L = 20 the intensity value reduces to a minimum. The intensities in Rayleigh (R) for HLy‐α from H, HLy‐α from H2, Lyman and Werner bands of H2 are calculated. Comparing these intensities with the diffuse auroral intensities observed at Saturn, it is found that the intensities at Jupiter are higher than the values predicted for Saturn. We have also calculated volume ionization rates for atomic H producing H+, dissociative ionization of H2 producing H+, and ionization of H2 producing H2+. The continuity equation is solved to obtain the electron density Outcomes are discussed. Key Points: This is first very comprehensive study of diffuse auroral emissions on Jupiter driven by ECH waves at five shells L = 10, 12, 15, 18, 20Precipitation of soft electrons (

The holmium (Ho3+) ions-based fluoro borosilicate (SBNCHo) glasses have been prepared using the traditional melt quenching technique with varying concentrations of Ho3+ ions. Physical parameters were analyzed using x-ray diffraction, energy dispersive analysis of x-rays, fourier transform infrared spectroscopy, optical, luminescence, and Commission International de I'Eclairage (CIE) studies. Judd-Ofelt spectral intensity parameters were evaluated for SBNCHo_1.0 (Ω 2 = 5.292 x 10-20 cm2, Ω 4 = 3.062 x 10-20 cm2 and Ω 6 = 3.376 x 10-20 cm2) glass, optical bandgaps were estimated using optical absorption studies. The Photoluminescence emission spectra were recorded for synthesized glasses with 452 nm excitation. The stimulated emission (σ e = 1.40 x 10-20 cm2) for the intense green radiation (5S 2 (5F 4) → 5I 8) was calculated. The lifetime decay profile was analyzed for all the synthesized glasses. From the CIE color coordinates of SBNCHo glasses, the color purity was estimated to be (SBNCHo_1.0 (98.6 %)). These results strongly support the applicability of SBNCHo_1.0 glass for green laser applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Potential‐induced degradation (PID) is a prevalent concern in current commercial photovoltaic technologies, impacting their reliability, with the mechanistic basis for PID in perovskite photovoltaic technologies being poorly understood. Here, we investigate the PID mechanism in perovskite minimodules. Our findings reveal nonuniform degradation in the photoluminescence intensity and spectral blue shift. After 60‐h laboratory PID stress tests at −1500 V and 60°C, device efficiency drastically decreases by 96%, and the shunt resistance decreases by 97%, accompanied by a significant quantity of Na+ ions (derived from the soda lime glass) throughout the device structure, leading to a typical PID‐shunting effect. Interestingly, we observed a rapid recovery of device performance during room‐temperature dark storage, in which Na+ ions located close to the glass substrate side rapidly migrated out of the device. Moreover, we also found that the Na+ ions do not appear to diffuse through the grain boundaries but rather their neighboring area and grain interiors, judging by microscopic conductivity mappings. [ABSTRACT FROM AUTHOR]

The inversion of temperature by detecting the ratio of the intensity of airglow vibrational and rotational spectral lines is a traditional method for obtaining mesopause temperature. However, previous studies have shown that there is significant uncertainty in the temperature inversion using this technology. A spectrograph instrument called the Mesosphere Airglow Fine Spectrometer (MAFS) was previously developed by our research team. Based on the MAFS, this work systematically evaluated the impact of the spectral line extraction methods and residual background noise elimination methods on temperature inversion results of the OH (6-2) Q-branch as the target. The fitting of residual background noise using different numbers of sampling points can cause the inverted temperature to vary by 5 K to 10 K without changing the overall trend. The temperature inversion results obtained using the three-region single-fit method were generally 3 K to 5 K higher than those obtained using the two-region double-fit method. Moreover, the temperature obtained using the Gaussian fitting area varied by approximately 15 K, with changes in the residual background noise fitting method; however, when using a spectrum peak instead of the Gaussian fitting area, this variation decreased to approximately 10 K. When the temperature is higher, both the residual background noise fitting and the spectral line intensity extraction methods have a more significant impact on the uncertainty of temperature inversion. [ABSTRACT FROM AUTHOR]

Fiber-optic sensors, such as fiber Bragg grating (FBG) sensors and fiber-optic interferometers, have excellent sensing capabilities for industrial, chemical, and biomedical engineering applications. This paper used machine learning to enhance the number of fiber-optic sensing placement points and promote the cost-effectiveness and diversity of fiber-optic sensing applications. In this paper, the framework adopted is the FBG cascading an interferometer, and a deep belief network (DBN) is used to demodulate the wavelength of the sampled complex spectrum. As the capacity of the fiber-optic sensor arrangement is optimized, the peak spectra from FBGs undergoing strain or temperature changes may overlap. In addition, overlapping FBG spectra with interferometer spectra results in periodic modulation of the spectral intensity, making the spectral intensity variation more complex as a function of different strains or temperature levels. Therefore, it may not be possible to analyze the sensed results of FBGs with the naked eye, and it would be ideal to use machine learning to demodulate the sensed results of FBGs and the interferometer. Experimental results show that DBN can successfully interpret the wavelengths of individual FBG peaks, and peaks of the interferometer spectrum, from the overlapping spectrum of peak-overlapping FBGs and the interferometer. [ABSTRACT FROM AUTHOR]

In this work, the glow spectrum from a neon strip lamp, used in homes and all private places, was diagnosed using optical emission spectroscopy (OES), to measure plasma parameters from spectral data (electrons density, electrons temperature, plasma frequency, Debye length). The intensity of the emission spectrum increases with increasing the applied voltage (100-220V). A spectral diagnosis was made of the cold plasma generated by the neon glow system where the glow spectrum produced was prepared for the diagnosis at variable alternating voltages that begin to rise gradually. The diagnosis was made at atmospheric pressure and room temperature of 27 ̊C. The results showed a gradual increase in the intensity of the neon spectrum generated by the system with the amount of gradual increase in the applied voltage. Between (250-850) nm, the behavior of neon spectral lines varied between high and low spectral intensity peaks. [ABSTRACT FROM AUTHOR]

Red solar-induced chlorophyll fluorescence (SIFB) is closely related to the photosynthetically active radiation absorbed by chlorophyll. The scattering and reabsorption of SIFB by the vegetation canopy significantly change the spectral intensity and shape of SIF, which affects the relationship between SIF and crop stress. To address this, we propose a method of modifying SIFB using SIF spectral shape characteristic parameters to reduce this influence. A red pseudokurtosis (PKB) parameter that can characterize spectral shape features was calculated using full-spectrum SIF data. On this basis, we analyzed the photosynthetic physiological mechanism of PKB and found that it significantly correlates with both the fraction of photosynthetically active radiation absorbed by chlorophyll(fPARchl) and the red SIF escape rate (fesc680); thus, it is closely related to the scattering and reabsorption of SIFB by the vegetation canopy. Consequently, we constructed an expression of PKB to modify SIFB. To evaluate the modified SIFB (MSIFB) in monitoring the severity of wheat stripe rust, we analyzed the correlations between SIFB, MSIFB, SIFB-VIs (a fusion of the vegetation index and SIFB), and MSIFB-VIs (a fusion of the vegetation index and MSIFB) with the severity level (SL), respectively. The results show that the correlation between MSIFB and the severity of wheat stripe rust increased by an average of 25.6% and at least 16.95% compared with that for SIFB. In addition, we constructed remote sensing monitoring models for wheat stripe rust using linear regression methods, with SIFB, MSIFB, SIFB-VIs, and MSIFB-VIs as independent variables. PKB significantly improves the accuracy and robustness of models based on SIFB and its fusion index SIFB-VIs in the constructed testing set. The R-value between the predicted SL and the measured SL of the remote sensing monitoring model for wheat stripe rust was established using MSIFB-VIs as the independent variable, and it was improved by an average of 39.49% compared with the model using SIFB-VIs. The RMSE was reduced by an average of 18.22%. Therefore, the SIFB modified by PKB can weaken the effects of chlorophyll reabsorption and canopy architecture on SIFB and improve the ability of SIFB to detect stress information. [ABSTRACT FROM AUTHOR]

Studying efficient and accurate soil heavy-metal detection technology is of great significance to establishing a modern system for monitoring soil pollution, early warning and risk assessment, which contributes to the continuous improvement of soil quality and the assurance of food safety. Laser-induced breakdown spectroscopy (LIBS) is considered to be an emerging and effective tool for heavy-metal detection, compared with traditional detection technologies. Limited by the soil matrix effect, the LIBS signal of target elements for soil heavy-metal detection is prone to interference, thereby compromising the accuracy of quantitative detection. Thus, a series of signal-enhancement methods are investigated. This study aims to explore the effect of conductive materials of NaCl and graphite on the quantitative detection of lead (Pb) in soil using LIBS, seeking to find a reliable signal-enhancement method of LIBS for the determination of soil heavy-metal elements. The impact of the addition amount of NaCl and graphite on spectral intensity and parameters, including the signal-to-background ratio (SBR), signal-to-noise ratio (SNR), and relative standard deviation (RSD), were investigated, and the mechanism of signal enhancement by NaCl and graphite based on the analysis of the three-dimensional profile data of ablation craters and plasma parameters (plasmatemperature and electron density) were explored. Univariate and multivariate quantitative analysis models including partial least-squares regression (PLSR), least-squares support vector machine (LS-SVM), and extreme learning machine (ELM) were developed for the quantitative detection of Pb in soil with the optimal amount of NaCl and graphite, and the performance of the models was further compared. The PLSR model with the optimal amount of graphite obtained the best prediction performance, with an Rp that reached 0.994. In addition, among the three spectral lines of Pb, the univariate model of Pb I 405.78 nm showed the best prediction performance, with an Rp of 0.984 and the lowest LOD of 26.142 mg/kg. The overall results indicated that the LIBS signal-enhancement method based on conductive materials combined with appropriate chemometric methods could be a potential tool for the accurate quantitative detection of Pb in soil and could provide a reference for environmental monitoring. [ABSTRACT FROM AUTHOR]

Improving the efficiency of laser-induced breakdown spectroscopy (LIBS) is crucial for its clinical applicability in tumor diagnosis. This study presents an accelerated diagnostic approach based on a kernel principal component analysis-support vector machine (KPCA-SVM) model. Initially, elemental features--calcium (Ca), sodium (Na), magnesium (Mg), and copper (Cu)--were selected due to noticeable differences in spectral intensity between tumor and normal tissues. Subsequently, employing KPCA facilitated the projection of LIBS features into a high-dimensional space, capturing nonlinear data relationships. Dimensionality reduction within this space was then performed to retain essential nonlinear features while eliminating redundancy. The resulting reduced matrix was input into the SVM classifier. Both the Gaussian kernel of KPCA and the Radial Basis Function (RBF) kernel of the SVM exhibited exceptional diagnostic efficacy. Optimal results were attained using 15 principal components, achieving a classification accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 99.03%, 99.72%, 98.89%, 98.90%, and 99.72%, respectively. Importantly, the model's runtime was only 6.77 seconds, highlighting the potential of KPCA and SVM kernel methodologies for rapid lung cancer diagnosis. [ABSTRACT FROM AUTHOR]

Owing to the complex laser-material interaction, large spectral fluctuation is one of the main causes of the relatively poor qualitative analysis performance of laser-induced breakdown spectroscopy (LIBS). In this study, a data preprocessing method, namely minimum distance and subsequent averaging (MD & A) using plasma image information, is proposed to identify effective spectra and improve the spectral stability of LIBS. The correlations between plasma image features and spectral line intensity were analyzed, which indicated that plasma average area intensity showed high correlation with plasma states. To evaluate the performance of the proposed method, original spectra were preprocessed by other traditional screening methods, and then, different quantitative models for Mn, Cu, Cr and Si elements in steel samples were separately established based on the partial least squares regression (PLSR) algorithm. Compared to the original spectra, the evaluation parameter R2 is improved to nearly 99% from 93% while the values of mean root mean squared error of prediction (RMSEP) and mean average relative error of prediction (AREP) are also reduced by over 50%. In addition, the mean relative standard deviation (RSD) of different spectral line intensities using MD & A can be reduced to the range of 1.07% to 3.12% from the range of 3.76% to 18.48%. The above results indicate that our proposed method can be easy to realize and significantly improve the spectral stability and quantitative analysis performance of LIBS compared to traditional methods. [ABSTRACT FROM AUTHOR]

Even with 100% certainty of a complete cure for breast cancer (BC), there is still a long way to go toward more efficient treatment because it requires sensitive and timely detection and accurate pre/post-clinical characterizations. Despite the availability of advanced diagnostic tools, many cancer patients lack access to efficient diagnostics that are both highly reliable and affordable. The fluorescence-based optical technique aims to make another significant leap forward in improving patient safety. It offers a convenient operation that reduces healthcare costs compared to visual examination tools (VETs). The primary and metastatic stages of BC consider different cancerous cell lines (MDAs), meaning the highest number of cells in this research (up to 300,000) represents the metastatic stages of BC, and 50,000 represents the primary level of BC. Developments have been studied based on fluorescence-enhanced photodynamic characterizations. The ability to characterize the fluorescence caused by MDA with 50,000 cells compared to the dominant radiation of MDA with 300,000 cells is emphatic proof of the high potential of fluorescence technique in timely BC detections, specifically before it spreads to the axillary lymph nodes. The specific cell numbers of 50,000 and 300,000 were chosen arbitrarily based on the cultivation of common biological limitations. Comparing the outcomes between 50,000 and 300,000 cells allows for evaluating the fluorescence technique's diagnostic capability across various stages of breast cancer. This assessment provides valuable insights into the effectiveness of the fluorescence-based characterizing approach in detecting cancerous cells at different stages of the disease. Here, we have assessed fluorescence's spectral shift and intensity difference as a diagnostic approach to distinguish between cancerous and normal breast cells. This study also presents a two-way structure of the 5-aminolevulinic acid (5-ALA) prodrug and Fluorescein Sodium (FS) effect in BC cell characterization from the perspective of photodynamical procedures and the detection side. 5-ALA induces an accumulation of protoporphyrin IX (PpIX) photosensitizer through a biosynthetic pathway, leading to red radiation of fluorescence measurements depending on different factors, such as temperature, incubation time, added glucose of the culturing medium, as well as photosynthesis processes. The presence and progression of breast cancer can be indicated by elevated levels of Reactive Oxygen Species (ROS), associated with the production of PpIX in cells following the administration of 5-ALA. In addition, nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) fluorophores are recognized as the main factors for fluorescence emissions at around 420–580 nm emission intervals. Considering the MDA's high metastatic potential, the impact of 5-ALA on MDA's cellular morphology and viability has been investigated. The molecular fluorophores are the primary probes to MDA's cellular photodynamic considerations, allowing this widespread pre/post-clinical approach. The fluorescence signal reduction due to decreased cell viability and increased MDA's cellular death rate after 24 h of the 5-ALA-induced staining corresponds to the changes in lipid metabolism enzymes of MDAs cultured at different doses, which could be known as a cell death inducer function. Furthermore, statistical concerns have been studied using PCA multivariate component analysis to differentiate MDA cell lines administrated by 5-ALA. [ABSTRACT FROM AUTHOR]

In the present work, analyses have been performed to determine spectroscopic parameters, including transition probabilities, and relative line strengths of discharge-produced xenon plasma. We present the transition probabilities of twenty-three emission lines originating from the 5p56p →5p56s transition array of neutral xenon covering the wavelength range from 450 to 1100 nm using a xenon-filled hollow cathode discharge lamp. The experimental absolute transition probabilities have been measured by combining the reported lifetimes of upper levels with the integrated spectral intensities of xenon transitions. The results agree well with the reported data in the NIST database, where available. The theoretical line strengths for all spectral transitions originating from the 5p56p→5p56s transition array have been calculated in the LS, LK, jj, and jck coupling schemes using the 3j, 6j, and 9j symbol relations. Furthermore, the normalized experimental line strengths have also been measured and compared with theoretical line strengths, which confirm that the jj and jck coupling scheme is more appropriate for the level designation of xenon. [ABSTRACT FROM AUTHOR]

Lead-free Cs3Cu2I5 metal halides have garnered significant attention recently due to their non-toxic properties and deep-blue emission. However, their relatively low photoluminescence quantum efficiency and poor stability have limited their applications. In this work, sodium iodide (NaI) is used to facilitate the synthesis of Cs3Cu2I5 nanocrystals (NCs), demonstrating improved photoluminescence intensity, photoluminescence quantum yield, and stability. Systematic optoelectronic characterizations confirm that Na+ is successfully incorporated into the Cs3Cu2I5 lattice without altering its crystal structure. The improved Photoluminescence Quantum Yield (PLQY) and stability are attributed to the strengthened chemical bonding, which effectively suppresses vacancy defects in the lattice. Additionally, light-emitting diodes (LEDs) based on 10% NaI-doped Cs3Cu2I5 NCs were assembled, emitting vibrant blue light with a maximum radiant intensity of 82 lux and Commission Internationale de l'Eclairage (CIE) chromaticity coordinates of (0.15, 0.1). This work opens new possibilities for commercial lighting display applications. [ABSTRACT FROM AUTHOR]

The Saha-IESC (Saha Ionisation Equilibrium Shift Correction) is a novel approach designed to correct for ionisation interference in the analysis of various solution samples. It integrates the Saha equation, plasma electroneutrality, the ideal gas equation, and the mass conservation equation to determine electron densities and the densities of various particles. Then, it establishes a correlation between spectral line intensities, particle densities, and concentrations, allowing for accurate quantitative analyses. For plasma sources deviating from LTE (Local Thermodynamic Equilibrium), the model introduces a variety of plasma temperatures. Saha-IESC can accurately quantify both macro and trace elements without strict matrix matching between the standard and samples to be tested. Nor does it require a large number of samples as in machine learning. When combined with the concept of spectral standardisation, it can also correct the spectral intensities. After calibration, the R2 values of the calibration function of elements in the certified reference materials (CRM) GWB(E)130459 were improved from 0.7599–0.9971 to 0.9902–0.9999. And the detection accuracies for several elements in the two certified reference samples were in the range of 90–104% (GWB(E)130459) and 89–102% (BWR3030-2016), respectively. The robustness of the model was assessed through spiked recoveries of six elements in four brines. The range of spiked recoveries was 94–150% (external standard), 97–152% (internal standard), and 80–120% (Saha-IESC), respectively. The Saha-IESC can greatly reduce the complexity of experimental design, while effectively suppressing the ionisation interference. [ABSTRACT FROM AUTHOR]

Improving long-term stability is an important issue for large-scale applications of laser-induced breakdown spectroscopy (LIBS). Unlike laboratory instruments, many applications of LIBS instruments are in harsh outdoor environments, where instrument drift can lead to deterioration of long-term stability, hindering the use of LIBS technology in applications with high-precision requirements. In this work, based on the designed LIBS sensor for molten steel, we analyzed the spectral drift problem of different day measurements, on the basis of which we proposed a drift correction method combining the internal standard and the dominant factor partial least squares (PLS) regression. In this method, spectra are first preprocessed to build an internal standard model of the elemental concentration ratios to spectral line intensity ratios. Then the PLS regression is utilized to construct a corrected model between the spectral intensity and the drift value of the intensity ratio. Finally, elemental concentration predictions are made by using the established internal standard model with modified spectral line intensity ratios. The method was tested on low alloy steel samples. In the experiment, the detection spectra were recorded for 9 days for quantitative analysis and drift correction of the major elements C, Si, Cr, Ni, Cu, and Mn in alloy steels. Compared with the uncalibrated internal standard method, for the prediction of unknown samples over a long period of time, the RMSE values of C, Si, Cr, Ni, Cu, and Mn decreased by 48.74%, 50.00%, 73.30%, 72.15%, 72.57%, and 18.23%, respectively, and the RSD decreased by 27.71%, 42.97%, 35.17%, 38.95%, 55.58%, and 23.40%, respectively. Furthermore, several typical drift correction methods were also studied for comparison, and the proposed method achieved the best results for different test sets. [ABSTRACT FROM AUTHOR]

This paper deals with self-absorption in a cylindrical high-pressure Hg–TℓI discharge for which local thermodynamic equilibrium can be assumed. Calculations of the densities of species, especially thallium, have been performed using a parabolic temperature profile and a constant mercury/thallium ratio throughout the discharge tube. This paper focuses on studying the self-absorption thallium lines by comparing them to those of mercury. Particular attention has been paid to the study of the additive effects on the self-absorption of spectral intensities. [ABSTRACT FROM AUTHOR]

The thermal and electrical properties of photovoltaic cell (PVC) under linear phenomenological heat transfer law between it and the environment is studied through finite time thermodynamics and the volt-ampere characteristic equation. The properties of PVC are affected by heat transfer between PVC and environment. There are optimal solar radiation intensity and PVC output voltage (OV), which make the photoelectric conversion efficiency (PECE) of PVC reach the highest value. When OV and solar radiation intensity are 28.50 V and 700 W/m2, the maximum PECE is 0.156. There is also the best solar radiation intensity, which makes the open-circuit voltage (OCV) reach the maximum. When solar radiant intensity is 669 W/m2, the maximum OCV is 33.14 V. The values of power output and short-circuit current (SCC) are monotonically increasing with solar radiation intensity. Given solar radiation intensity, the power output and OV exhibit a parabolic shape. The operating temperature falls first and then grows with the OV. However, the change of operating temperature with OV is not much. Band gap is a decreasing function of operating temperature. This article can give theoretical support for the design and use of PVCs. [ABSTRACT FROM AUTHOR]

Since FTIR is a sensitive micro-region measurement method, research on the impact of the heterogeneity of both aggregates and asphalt mortar is meaningful and comprehensive for accurate measurement with FTIR spectroscopy. In this paper, the impact of the heterogeneity of aggregates coated with asphalt mortar on their FTIR spectra and spectral reproducibility was creatively studied. The comparative analysis of the respective absorption peaks indicated that the characteristic absorption peaks of the aggregate coated with asphalt mortar were the superposition of the respective absorption peaks of its components. And research on the spectra of the coated aggregates obtained from the same batch of asphalt mixture fabricated at the same time showed that significantly different peak intensities could be affected by minor variations in their components due to the heterogeneity. Furthermore, statistical analysis suggested that the original spectral reproducibility of the coated aggregates was greatly affected by their heterogeneity, with a high coefficient of variation values. In conclusion, the heterogeneity of the coated aggregates could affect peak intensities and spectral reproducibility in micro-regions. [ABSTRACT FROM AUTHOR]

Organic/inorganic hybrid perovskite materials, such as CH3NH3PbX3 (X = I, Br), have attracted the attention of the scientific community due to their excellent properties such as a widely tunable bandgap, high optical absorption coefficient, excellent power conversion efficiency, etc. The exposure of perovskite solar cells and photovoltaic devices to heat can significantly degrade their performance. Therefore, elucidating their temperature-dependent optical properties is essential for performance optimization of perovskite solar cells. We synthesized CH3NH3PbBr3 (MAPbBr3) single crystals through the polymer-controlled nucleation route and investigated the optical properties and molecular structure evolution of them with temperature. Through temperature evolution photoluminescence (PL) spectroscopy, we found that the fluorescence intensity was greatly affected by increasing the temperature, with an asymmetric PL profile suggesting that more captured excitons undergo radiative complexation. The optical photographs showed that the color of MAPbBr3 single crystals faded. Raman spectroscopy revealed that during the heating process, the structure of MAPbBr3 was still preserved at 90 °C since all of the Raman bands were very clear. When the temperature increased to 120 °C, the Raman bands of the internal modes became very weak. On further heating, the inorganic framework on sample's surface started to disintegrate above 210 °C. During the heating process, the PL spectra exhibited significant changes in spectral intensity, peak position and Full Width Half Maximum (FWHM). The PL spectral intensity decreased abruptly with increasing temperature. The peak position was blue shifted with increasing temperature, and the peak shape showed an obvious asymmetry. The FMWH of the PL spectra was gradually broadened with the increase in the temperature, and there was a sharp increase from 270 °C to 300 °C. These variations in the PL spectra with temperature indicate that the optical properties of MAPbBr3 are greatly affected by temperature, which in turn affects the application of MAPbBr3 in fields such as optical devices. These results may be instructive for the application of MAPbBr3. [ABSTRACT FROM AUTHOR]

Turbulence is a fundamental process that drives mixing and energy redistribution across a wide range of astrophysical systems. For warm (T≈104 K) plasma, the material is partially ionized, consisting of both ionized and neutral species. The interactions between ionized and neutral species are thought to play a key role in heating (or cooling) of partially ionized plasmas. Here, mixing is studied in a two-fluid partially ionized plasma undergoing the shear-driven Kelvin–Helmholtz instability to evaluate the thermal processes within the mixing layer. Two-dimensional numerical simulations are performed using the open-source (PIP) code that solves for a two-fluid plasma consisting of a charge-neutral plasma and multiple excited states of neutral hydrogen. Both collisional and radiative ionization and recombination are included. In the mixing layer, a complex array of ionization and recombination processes occur as the cooler layer joins the hotter layer, and vice versa. In localized areas of the mixing layer, the temperature exceeds the initial temperatures of either layer with heating dominated by collisional recombinations over turbulent dissipation. The mixing layer is in approximate ionization-recombination equilibrium, however the obtained equilibrium is different to the Saha–Boltzmann local thermal equilibrium. The dynamic mixing processes may be important in determining the ionization states, and with that intensities of spectral lines, of observed mixing layers. This article is part of the theme issue 'Partially ionized plasma of the solar atmosphere: recent advances and future pathways'. [ABSTRACT FROM AUTHOR]

Background and objective: Standard normal variate (SNV) preprocessing is widely applied to spectroscopic data prior to multivariate modeling, under the assumption that it mitigates undesired background variations while preserving analyte signal information. However, the scaling step in SNV, where each spectrum is divided by its standard deviation, could potentially distort the covariance between spectral intensities and component concentrations. This study systematically evaluates the effect of SNV preprocessing on the ability to develop accurate quantitative models for determining analyte concentrations in mixtures, with a focus on the determination of moisture in corn using NIR spectroscopy. Materials and methods: Simulations were performed to generate single and multi-component spectroscopic datasets with varying levels of multiplicative scatter and baseline offset effects. Additionally, an experimental near-infrared (NIR) dataset for corn samples with reference moisture values was utilized. Partial least squares (PLS) regression was employed to model the simulated and experimental data, with and without SNV preprocessing. Model calibration and prediction performance metrics were assessed. Results and conclusion: For simulated datasets without background interferences, SNV preprocessing eliminated useful concentration-related variations by forcing all sample spectra to equal lengths, severely degrading PLS calibration and prediction abilities. In scenarios with multiplicative/additive perturbations, while SNV mean-centering helped mitigate these undesired effects, the subsequent scaling step obscured analyte concentration information in the spectral intensities. PLS models built from raw corn NIR spectra provided excellent determination of moisture in corn using NIR spectroscopy, whereas SNV preprocessing led to significantly higher prediction errors. The findings demonstrate that indiscriminate application of SNV can be detrimental for precise quantitative spectroscopic analysis by disrupting the covariance between signals and analyte levels. Therefore, preprocessing strategies should be judiciously evaluated based on the specific data characteristics and modeling objectives. [ABSTRACT FROM AUTHOR]

The repeated emergence of NADP–malic enzyme (ME), NAD–ME and phosphoenolpyruvate carboxykinase (PEPCK) subtypes of C4 photosynthesis are iconic examples of convergent evolution, which suggests that these biochemistries do not randomly assemble, but are instead specific adaptations resulting from unknown evolutionary drivers. Theoretical studies that are based on the classic biochemical understanding have repeatedly proposed light‐use efficiency as a possible benefit of the PEPCK subtype. However, quantum yield measurements do not support this idea. We explore this inconsistency here via an analytical model that features explicit descriptions across a seamless gradient between C4 biochemistries to analyse light harvesting and dark photosynthetic metabolism. Our simulations show that the NADP–ME subtype, operated by the most productive crops, is the most efficient. The NAD–ME subtype has lower efficiency, but has greater light harvesting plasticity (the capacity to assimilate CO2 in the broadest combination of light intensity and spectral qualities). In both NADP–ME and NAD–ME backgrounds, increasing PEPCK activity corresponds to greater light harvesting plasticity but likely imposed a reduction in photosynthetic efficiency. We draw the first mechanistic links between light harvesting and C4 subtypes, providing the theoretical basis for future investigation. Summary statement: NAD‐malic enzyme (ME) and phosphoenolpyruvate carboxykinase C4 subtypes have greater light harvesting plasticity but lower efficiency than the NADP–ME subtype. [ABSTRACT FROM AUTHOR]

In this study, we introduce a novel class of partially coherent vector sources, namely radially polarized spatiotemporally partially coherent cosine-Gaussian-correlated Schell-model pulsed (CGCSMP) beams, which are natural extensions of the scalar Gaussian Schell-model pulsed beams. The conditions for the physical realization of this source are established, and analytical formulae for the two-point, two-frequency cross-spectral density matrix elements of a beam propagating through turbulent atmosphere are derived within the framework of the extended Huygens–Fresnel principle and the atmospheric turbulence spectrum model. The behaviors of the spectral intensity, the spectral degree of polarization (DOP), and the spectral degree of coherence (DOC) of the beam during transmission are investigated numerically. Our work enriches the classical theory of propagating stochastic electromagnetic beams and may be useful for applications requiring a specified degree of beam coherence. [ABSTRACT FROM AUTHOR]

For in situ detection via laser-induced breakdown spectroscopy (LIBS), the effect of the sample surface morphology matrix exacerbates spectral variations, leading to inaccurate and unstable analysis results, even under ideal laboratory conditions. Thus, it is essential to consider the influence of sample surface morphology on LIBS to obtain optimal detection results. Therefore, to reduce this influence, herein, we proposed spectral correction methods to correct LIBS spectra based on our previous research results on the relationship between LIBS characteristic spectral intensity and physical parameter of the sample surface morphology, where the parameter was the angle θ between the tangent of the sample surface and the horizontal direction. The results showed that the fluctuations in the corrected spectra were reduced and the relative standard deviation (RSD) was less than 10%, and the spectral intensities were close to that of the samples with a flat surface morphology. To assess the effectiveness of the proposed methods in improving the quantitative analysis accuracy, Cr, Ni, and Mn elements in standard stainless-steel samples were analyzed by partial least squares regression (PLSR). We established the model using the spectra of standard samples with a flat surface morphology as the training set, and the results showed that the accuracy was very low when the test set was the spectra of samples without a flat surface morphology, with R² of 0.781, 0.779, and 0.695 for Cr, Ni, and Mn elements, respectively. In contrast, when the test set was the corrected spectra, R2 increased to 0.950, 0.925, and 0.825 for Cr, Ni, and Mn elements, respectively, and the RMSE and MRE were reduced. When the corrected spectra of standard samples without a flat surface morphology were added to the training set, the accuracy was improved, with R² of 0.978, 0.939, and 0.929 for the three elements and their RMSE and MRE were minimum. [ABSTRACT FROM AUTHOR]

Mass spectrometry (MS) is a highly selective and sensitive analytical tool with a myriad of applications, but such techniques are typically used in laboratory settings due to the handling and preparations that are necessary. The merging of two streams of robust research, portable MS systems and next-generation ambient ionization methods, now provides the ability to perform high-performance chemical screening in an on-site and on-demand manner, with natural applications in disciplines such as forensic science, where samples of interest are typically found in field environments (i.e., traffic stops, crime scenes, etc.). Correspondingly, investigations regarding the suitability and robustness of these methodologies when they are utilized for authentic forensic evidence processing are prudent. This work reports critical insights into the role that choice of spray solvent system plays regarding analytical performance of two spray-based ambient ionization sources, paper spray ionization (PSI) and filter cone spray ionization (FCSI), when employed for evidence types containing emerging synthetic cannabinoids. The systematic characterization studies reported herein show that the applied spray solvent can dramatically affect both spectral intensity and signal duration, and in some circumstances, yield deleterious false negative responses. Overall, acetonitrile-based systems are shown to strike a balance between analyte solubility concerns and spray ionization dynamics of the novel ion sources employed on portable MS systems. [ABSTRACT FROM AUTHOR]

This work reports the full quantum calculations of the spectral line shape parameters for the P(22) line of 13CO and the P(31) line of 12CO in the fundamental band perturbed by He or Ar from 20 to 1000 K for the first time. The generalized spectroscopic cross sections of CO–He/Ar indicate that the Dicke narrowing effect competes with the pressure broadening effect. The pressure broadening can be explained by the dynamic behaviors of intermolecular collisions. The intermolecular inelastic collisions contribute more than 95% to the pressure broadening in both CO–He and CO–Ar systems at high temperatures. Regarding the state-to-state inelastic contributions to pressure broadening, the maximum contribution out of the final state of a given line is close to that out of the initial state. The Dicke narrowing effect influences the line shape profile significantly at high temperatures, which suggests that it is indispensable for reproducing the spectral line profile. With the Dicke narrowing effect, the calculated pressure-broadening coefficients and spectral intensity distribution are in good agreement with the available experimental observations. [ABSTRACT FROM AUTHOR]

Background: Intravenously administered indocyanine green (ICG) accumulates in lung tumors, facilitating their detection via a fluorescence spectrum measurement. This method aids in identifying tumor locations that are invisible to the naked eye. We aim to determine the optimal ICG dose and administration method for accurate tumor identification during lung resection surgeries, utilizing a novel ICG fluorescence spectroscopy system for precise tumor localization. Materials and Methods: ICG should be dissolved in the provided solution or distilled water and administered intravenously approximately 24 h before surgery, beginning with an initial dose of 0.5 mg/kg. If the tumor detection rate is insufficient, the dose may be gradually increased to a maximum of 5.0 mg/kg to determine the optimal dosage for effective tumor detection. This fluorescence spectroscopy during surgery may reveal additional lesions that remain undetected in preoperative assessments. The primary endpoint includes the correct diagnostic rate of tumor localization. The secondary endpoints include the measurement of the intraoperative ICG fluorescence spectral intensity in lung tumors, the assessment of the operability and safety of intraperitoneal ICG administrations, the measurement of the ICG fluorescence spectral intensity in surgical specimens, the comparison of the spectral intensity in lung tissues during collapse and expansion, the correlation between ICG camera images and fluorescence spectral intensity, and the comparison of fluorescence analysis results with histopathological findings. The trial has been registered in the jRCT Clinical Trials Registry under the code jRCTs011230037. Results and Conclusions: This trial aims to establish an effective methodology for localizing and diagnosing malignant lung tumors, thereby potentially improving surgical outcomes and refining treatment protocols. [ABSTRACT FROM AUTHOR]

To investigate the effect of potassium compound on the combustion characteristics of hydroxyl-terminated polybutadiene (HTPB) composite solid propellants. Potassium compound were added to the HTPB propellants as flame inhibitors at different concentration gradients, and the effects of the potassium compound on the thermal decomposition and combustion characteristics of these propellants were investigated by thermogravimetric differential calorimetric scanning calorimetry (TG-DSC) and laser ignition combustion experiments. The results showed that the effect of potassium compound on the thermal decomposition of the HTPB composite solid propellant predominantly occurred in the AP/HMX decomposition stage, and the potassium compound affected the synergistic decomposition of AP/HMX. The entire process of the HTPB composite solid propellant combustion slowed down with increasing potassium compound content; this was mainly shown by the increase in ignition delay time and longer combustion time. The intensity of the secondary combustion flame decreased, the maximum flame area and image grayness decreased, and the intensity of the maximum emission spectrum of the secondary combustion flame decreased. With the increase in potassium compound content, the spectral intensity of free radicals produced by combustion shows a decreasing intensity with a delayed trend with the change rule of time. Overall, the potassium compound weakened the combustion of the HTPB composite solid propellant. [ABSTRACT FROM AUTHOR]

Background: Cherenkov luminescence imaging has shown potential for relative dose distribution and field verification in radiation therapy. However, to date, limited research utilizing Cherenkov luminescence for absolute dose calibration has been conducted owing to uncertainties arising from camera positioning and tissue surface optical properties. Purpose: This paper introduces a novel approach to multispectral Cherenkov luminescence imaging combined with Fricke–xylenol orange gel (FXG) film, termed MCIFF, which can enable online full‐field absolute dose measurement. By integrating these two approaches, MCIFF allows for calibration of the ratio between two spectral intensities with absorbed dose, thereby enabling absolute dose measurement. Methods: All experiments are conducted on a Varian Clinac 23EX, utilizing an electron multiplying charge‐coupled device (EMCCD) camera and a two‐way image splitter for simultaneous capture of two‐spectral Cherenkov imaging. In the first part of this study, the absorbance curves of the prepared FXG film, which receives different doses, are measured using a fluorescence spectrophotometer to verify the correlation between absorbance and dose. In the second part, the FXG film is positioned directly under the radiation beam to corroborate the dose measurement capacity of MCIFF across various beams. In the third part, the feasibility of MCIFF is tested in actual radiotherapy settings via a humanoid model, demonstrating its versatility with various radiotherapy materials. Results: The results of this study indicate that the logarithmic ratios of spectral intensities at wavelengths of 550 ± 50 and 700 ± 100 nm accurately reflect variations in radiation dose (R2 > 0.96) across different radiation beams, particle energies, and dose rates. The slopes of the fitting lines remain consistent under varying beam conditions, with discrepancies of less than 8%. The optical profiles obtained using the MCIFF exhibit a satisfactory level of agreement with the measured results derived from the treatment planning system (TPS) and EBT3 films. Specifically, for photon beams, the lateral distances between the 80% and 20% isodose lines, referred to as the penumbra (P80‐20) values, obtained through TPS, EBT3 films, and MCIFF, are determined as 0.537, 0.664, and 0.848 cm, respectively. Similarly, for electron beams, the P80‐20 values obtained through TPS, EBT3 films, and MCIFF are found to be 0.432, 0.561, and 0.634 cm, respectively. Furthermore, imaging of the anthropomorphic phantom demonstrates the practical application of MCIFF in real radiotherapy environments. Conclusion: By combining an FXG film with Cherenkov luminescence imaging, MCIFF can calibrate Cherenkov luminescence to absorbed dose, filling the gap in online 2D absolute dose measurement methods in clinical practice, and providing a new direction for the clinical application of optical imaging to radiation therapy. [ABSTRACT FROM AUTHOR]