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Apatite structured polycrystalline samples of rare earth manganese silicates, La4MnSi3O13 and Y4MnSi3O13, were synthesized via ceramic route, and their crystal structure, morphology, dielectric, optical, and luminescence characteristics were thoroughly examined. Rietveld refinements of the X-ray diffraction data and Raman results confirm that both the compounds are formed in single phase, and crystallize in hexagonal crystal symmetry. Scanning electron microscopy micrographs show the crystalline nature of the synthesized silicates, and the sizes of the grains are found in submicron range. The dielectric constant and tanδ show systematic variation with frequency. The low values of tanδ of these ceramic samples suggest the potential use in energy storage capacitive devices. The calculated wide band gap energies (4.3 eV and 4.03 eV) of these new compositions of silicate apatites make them useful for better absorption and emission of UV light for applications in solid state lighting devices. The photoluminescence characteristics of La4MnSi3O13 and Y4MnSi3O13 samples make them beautiful sources of green-yellow and green emissions, respectively. [ABSTRACT FROM AUTHOR]

The process of transformation of the water-insoluble binuclear iron nitrosyl complex [Fe2(SC2N3C6H4NO2)2(NO)4] (1) in DMSO was studied. Using UV-vis spectrophotometry, it was shown that complex 1 decomposes in the solution. The theoretical electronic spectrum in the UV and visible regions was calculated for this complex using a TDDFT method, and an analysis of molecular orbitals of the complex was carried out. It was suggested that the disappearance of the absorption band due to an electronic transition involving the Fe—NO groups is associated with the NO donation. Using quantum chemical calculations, a total energy diagram of the decomposition of complex 1 in DMSO was obtained, and two mechanisms of its transformation, viz., one proceeding through an increase in the coordination number of the iron atom to 6 and the other occurring with breaking the Fe—S bonds with the μ-SCN bridge, were studied. [ABSTRACT FROM AUTHOR]

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Accurately identifying the kind and amount of dissolved metal salts in wastewater used in oil refining processes is an iconic feature of ultraviolet and visible absorption spectroscopy. This method relies on the dissolved metal salts' ability to absorb light at certain wavelengths after reacting with it. The experiments were conducted in a lab setting with a broadband source (200-800 nm) to measure the absorbance of dissolved element salts and precisely identify the lowest concentration up to 2 ppm. A mixture of the mineral salts from oil refining operations was prepared and diluted to different concentrations using a standard solution. This allowed us to study and compare this result with the absorbance behavior of the wastewater from the Al-Dora Refinery. The two results reinforced that we can accurately estimate the detection parameters for the lowest water contamination. These materials are lead nitrate (PbNO3), phenol, calcium carbonate (CaCO3), sodium chloride (NaCl2), sulfide (SO4), and nitrate (NO3). At wavelengths of 340, 404, and 741 nm, the concentrations (10, 20, 30, 40, 50, 60, 70, 80, 90, and 100) ppm were found, and for the concentration of 10ppm, the absorbance (0.15323, 0.15326, and 0.14685) was found, respectively. The process that has been tested with varying concentrations is considered and simulates the variation in river water concentrations caused by the river's water level and flow rate changes by the effect of rain abundance and thawing. It is fast, accurate data analysis, and a lower cost compared with the other chemical analysis and conventional methods.

Prostate apoptosis response‐4 (Par‐4) tumor suppressor protein has gained attention as a potential therapeutic target owing to its unique ability to selectively induce apoptosis in cancer cells, sensitize them to chemotherapy and radiotherapy, and mitigate drug resistance. It has recently been reported that Par‐4 interacts synergistically with cisplatin, a widely used anticancer drug. However, the mechanistic details underlying this relationship remain elusive. In this investigation, we employed an array of biophysical techniques, including circular dichroism spectroscopy, dynamic light scattering, and UV–vis absorption spectroscopy, to characterize the interaction between the active caspase‐cleaved Par‐4 (cl‐Par‐4) fragment and cisplatin. Additionally, elemental analysis was conducted to quantitatively assess the binding of cisplatin to the protein, utilizing inductively coupled plasma‐optical emission spectroscopy and atomic absorption spectroscopy. Our findings provide evidence of direct interaction between cl‐Par‐4 and cisplatin, and reveal a binding stoichiometry of 1:1. This result provides insights that could be useful in enhancing the efficacy of cisplatin‐based and tumor suppressor‐based cancer therapies. [ABSTRACT FROM AUTHOR]

This study focuses on the preparation of a high-performance visible light photodetector using nanocrystalline lead sulphide (PbS) thin films. The thin films were deposited onto glass substrates via the chemical bath deposition technique, utilizing an aqueous solution of lead acetate and thiourea. The structural study carried out on the deposited films by X-ray diffraction exhibited a cubic crystal structure with a PbS phase. The optical characteristics of PbS thin films were investigated employing UV-Vis absorption spectroscopy. The absorption spectroscopy was carried out in the wavelength range of 400–1000 nm. The absorbance spectra were utilized to calculate the spectral dependence of several optical parameters: band gap, refractive index, extinction coefficient, dielectric constant, and optical and electrical conductivity. The photocurrent was measured in nanocrystalline PbS thin films under the illumination of specific LED wavelength sources. The quality of the PbS thin film as a photodetector was investigated by determining the rise time, decay time, photosensitivity, specific detectivity, and external quantum efficiency. [ABSTRACT FROM AUTHOR]

The electronic absorption and vibrational spectra of deprotonated 5,10,15,20-tetrakis(p-hydroxyphenyl)porphyrin (THPP) are studied as a function of solvent polarity in H2O-DMF, H2O-acetone, H2O-methanol, and DMF-acetone mixtures. The maximum absorption wavelength (λmax) of the lowest energy electronic absorption band of deprotonated THPP shows an unusual solvatochromism-a bathochromic followed by a hypsochromic shift with reduced polarity. According to the correlation analysis, both specific interactions (H-bonds) and nonspecific interactions affect the spectral changes of this porphyrin. Furthermore, the solvent polarity scale ET(30) can explain both shifts very well. At higher polarity (ET(30) > 48), THPP exists as a hyperporphyrin. The ET(30) is linear with λmax and a decrease in solvent polarity is accompanied by a bathochromic shift of λmax. These results can be rationalized in terms of the cooperative effects of H-bonds and nonspecific interactions on the spectra of hyperporphyrin. At relatively low polarity (45.5 < ET(30) < 48), hyperporphyrin gradually becomes Na2P as ET(30) reaches the critical value of 45.5. The spectrum of the hyperporphyrin turns into the three-band spectrum of the metalloporphyrin, which is accompanied by a hypsochromic shift of λmax. [ABSTRACT FROM AUTHOR]

The electrochemical and spectroelectrochemical properties of the discotic mesogen 2,3,6,7,10,11-pentyloxytriphenylene (H5T) were studied with the use of cyclic voltammetry combined with UV-Vis and electron paramagnetic resonance (EPR) spectroscopy in solution. The UV-Vis absorption spectroscopy of H5T in dichloromethane showed its monomeric state in a concentration range up to 10−3 mol dm−3. The reversible process of the electrochemical formation of the radical cation was evidenced within the experimentally accessible potential window. The in situ UV-Vis spectroelectrochemical measurements further enabled identification of the product of the redox process and evaluation of the effect of aggregation in the concentration range of 5 × 10−3 mol dm−3. The results are discussed in the frame of solvent effects on the self-assembly propensity of solute molecules, in a wide range of concentrations. In particular, the crucial role of the solvent polarity is indicated, which contributes to the understanding of solution effects and pre-programming of supramolecular organic materials, in particular anisotropic disc-shaped hexa-substituted triphenylenes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Rapid and accurate identification of external water in rainwater pipelines. • A novel use of MSC combined with VMD for absorption spectroscopy analysis. • A new method for small samples identification of UV–Vis absorption spectroscopy. Ultraviolet–visible (UV–Vis) absorption spectroscopy, due to its high sensitivity and capability for real-time online monitoring, is one of the most promising tools for the rapid identification of external water in rainwater pipe networks. However, difficulties in obtaining actual samples lead to insufficient real samples, and the complex composition of wastewater can affect the accurate traceability analysis of external water in rainwater pipe networks. In this study, a new method for identifying external water in rainwater pipe networks with a small number of samples is proposed. In this method, the Generative Adversarial Network (GAN) algorithm was initially used to generate spectral data from the absorption spectra of water samples; subsequently, the multiplicative scatter correction (MSC) algorithm was applied to process the UV–Vis absorption spectra of different types of water samples; following this, the Variational Mode Decomposition (VMD) algorithm was employed to decompose and recombine the spectra after MSC; and finally, the long short-term memory (LSTM) algorithm was used to establish the identification model between the recombined spectra and the water source types, and to determine the optimal number of decomposed spectra K. The research results show that when the number of decomposed spectra K is 5, the identification accuracy for different sources of domestic sewage, surface water, and industrial wastewater is the highest, with an overall accuracy of 98.81%. Additionally, the performance of this method was validated by mixed water samples (combinations of rainwater and domestic sewage, rainwater and surface water, and rainwater and industrial wastewater). The results indicate that the accuracy of the proposed method in identifying the source of external water in rainwater reaches 98.99%, with detection time within 10 s. Therefore, the proposed method can become a potential approach for rapid identification and traceability analysis of external water in rainwater pipe networks. [ABSTRACT FROM AUTHOR]

The world’s rapid industrialisation and population expansion have led to water pollution, causing significant disruption to the activities of humans, animals, and plants. Organic contamination content in water is commonly evaluated by measuring the chemical oxygen demand (COD). However, traditional COD detection methods often require additional reagents, resulting in secondary contamination and extended detection time. In this study, we propose and implement a reflective detection system that measures the UV-Vis absorption spectra of COD in water without contact measurement. We compared the modeling results of the transmissive and reflective detection systems using three regression analysis algorithms. We also assessed the modeling results using various spectral preprocessing and different feature selection bands. The results of the standard samples confirmed the viability of the reflective detection system for detecting COD, with the impressive coefficient of determination (R2) of 0.98892, the root mean square error (RMSE) of 2.86776, and the detection time of only 47.6 s. For the transmissive detection system, the R2 was 0.99976, the RMSE was 0.41979, and the detection time was 162.4 s. Overall, this study proposes two referenceable detection methods for measuring COD concentrations, which can be adapted to suit various job demands.

Combined with photoelectric detection technology and UV-Vis absorption spectroscopy in spectral analysis technology, a multi-parameter portable surface water quality detection system is developed, which can quickly detect phosphate, nitrite, and chemical oxygen demand (COD) and ammonia nitrogen water quality parameters on site. For the substances in the water body that absorb the characteristic wavelengths in the visible part, a camera is used to collect the visible spectrum, and the grayscale image of the visible spectrum image is modeled by a convolutional neural network. The concentration value of substances whose absorption characteristic wavelength is in the ultraviolet band is measured by photoelectric detection technology. The established convolutional neural network model is transplanted into ZYNQ, combined with ultraviolet photoelectric sensor, the concentration value of the detected substance is displayed on the LCD, so as to realize the economy, portability, real-time and rapidity of the water quality detector. Research indicates: The prediction value of convolutional neural network is obtained as the tendency value of sample solution in 8 output types of concentration value, the highest accuracy is 100%, and the lowest is 40%. The highest error of COD concentration value is 10%, which proves that the detection system has practical value with low noise and high precision. [ABSTRACT FROM AUTHOR]

In this work, according to the data obtained from the induced circular dichroism spectra, the studied porphyrin binds to DNA by the intercalation method, and its Zn-containing analog by the externally ordered interaction was revealed. The absorption spectra of the studied complexes were obtained at different DNA concentrations, and the binding parameters (Kb, n) of porphyrins with DNA were computed from the data at two values of the ionic strength of the solution. It is shown that the places for binding porphyrins become less accessible at a higher ionic strength of the solution. An increase in the melting temperature of DNA in the presence of a metal-containing porphyrin is also observed, as well as a decrease in the stabilizing effect of porphyrins for an increase in the ionic strength of the solution. [ABSTRACT FROM AUTHOR]

The photochromic properties of 4,4′-dihydroxyazobenzene diglycidyl ether have been investigated to gain further insight into the photoisomerization pathways. The light induced trans–cis isomerization, thermal cis–trans recovery and light induced cis–trans isomerization were monitored using electronic absorption spectroscopy. The pohotoisomerization and thermal relaxation kinetics of azobenzene chromophores were investigated in solution. It was found that the trans–cis isomerization process occurs very fast and a high content of cis isomer was obtained (94 %). The optimization of the ground and transition state geometries as well as the electronic structure of the azo epoxy derivative was performed by the density functional theory (DFT) and time-dependent DFT with PBE0 and CAM-B3LYP functionals, using 6-31 + G(d,p) as basis set. Also, the theoretical UV–vis absorption spectra were calculated. The mechanism of isomerization along the S2, S1 and S0 energy levels has been described. It was shown how each internal coordinate contributes to the isomerization mechanism. TD-DFT and DFT methods revealed that modification of the NN bond length was the internal coordinate responsible for the trans to cis as well as cis to trans conversion.

Electronic structure of anionic cyclometallated platinum(II) benzene-1,2-dithiolate complex (PtSS–, 1) and its oxygenation products (PtSO2S–, 2; PtSSO , 3; and PtSO2SO , 4) have been theoretically examined using DFT calculations. Initially, structures of all complexes in their ground and lowest energy triplet excited state were optimized. Electronic structures, vertical excitation transitions, UV-Vis absorption spectra of all complexes in ground state and spin density of the excited state were calculated to analyze the effect of oxygenations. The results indicate that oxygenations induce significant changes in the nature of frontier orbitals, which are translated into marked blue shifts of lowest energy absorption band as well as emission energies of the complexes. [ABSTRACT FROM AUTHOR]

Two experimental procedures implying mechanochemical and ultrasounds assisted protocols were assessed as alternatives to the classical synthesis of the title MB analogue, based on the substitution of the phenothiazinium tetraiodide with diethanolamine nucleophile. These greener alternatives required a much shorter reaction time and consequently less energy consumption. The sonochemical procedure gave a crystalline reaction product demanding a facile purification. UV-vis spectroscopic analysis emphasized the optical properties of the 3,7- bis(N,N-(2-hydroxyethyl)amino)phenothiazinium dye characterized by an intense absorption maxima situated at 663 nm and weak fluorescence emission in aqueous solution (quatum yield 0.7% relative to methylene blue standard) with the emission maxima situated at 685 nm (Stokes shift 484 cm-1). The solid state structure of the dye was determined by X-ray diffraction. [ABSTRACT FROM AUTHOR]

Curcumin has been demonstrated to exhibit photosensitized bactericidal activity. However, the full exploitation of curcumin as a photo-pharmaceutical active principle is hindered by fast deactivation of the excited state through the transfer of the enol proton to the keto oxygen. Introducing an asymmetry in the molecular structure through acting on the phenyl substituents is expected to be a valuable strategy to impair this undesired de-excitation mechanism competing with the therapeutically relevant ones. In this study, two asymmetric curcumin analogs were synthesized and characterized as to their electronic-state transition spectroscopic properties. Fluorescence decay distributions were also reconstructed. Their analysis confirmed the substantial stabilization of the fluorescent state with respect to the parent compound. Nuclear magnetic resonance experiments were performed with the aim of determining the structural features of the keto–enol ring and the strength of the keto–enol hydrogen bond. Electronic structure calculations were also undertaken to elucidate the effects of substitution on the features of the keto–enol semi-aromatic system and the proneness to proton transfer. Finally, their singlet oxygen-generation efficiency was compared to that of curcumin through the 9,10-dimethylanthracene fluorescent assay. [ABSTRACT FROM AUTHOR]

Ultraviolet-visible absorption spectroscopy is widely used to monitor water quality, and rapid optical signal detection is a key technology in the process of spectrum measurement. In this paper, an ultrafast spectrophotometer system that can achieve spectrum data acquisition in a single flash of the xenon lamp (within 200 ns) is introduced, and a real-time denoising method for the spectrum is implemented on a field programmable gate array (FPGA) to work cooperatively with the nanosecond spectrum acquisition system, in order to guarantee the quality of the spectrum signals without losing running speed. The hardware of the data acquisition and processing system are constructed on a Xilinx Spartan 6 FPGA chip and its peripheral circuit, including an analog to digital converter and a complementary metal-oxide-semiconductor transistor (CMOS) sensor's diver circuit. An oversampling method that is suitable for the CMOS sensor's output is proposed, which works on the CMOS sensor's dark current noise and readout noise. Another moving-average filter method is designed adaptively, which works on the low-frequency component to filter out the residual spectrum noise of the spectrum signal. The implementation of the filter on the FPGA has been optimized by using a pipelined structure and dual high-speed random-access memory (RAM). As a result, the CMOS linear image sensor successfully captured the spectrum of xenon flash light at the readout clock frequency of 500 kHz and the processing manipulation to the full UV-Vis spectrum data was accomplished at a sub-microsecond speed performance. After the digital filter and oversampling technology were implemented, the coefficient of variation of the measurements reduced from 9.57% to 1.74%, while the signal noise ratio (SNR) of the absorption spectrum increased nine times, compared to the raw data of the CMOS sensor's output. The tests towards different analyte samples were conducted, and the system shows good performance on distinguishing different concentrations of different analyte solutions on both ultra-violet and visible spectrum bands. The present work showcases the potential of the CMOS sensor's technique for the fast detection of contaminated water containing nitrate and organic compounds. [ABSTRACT FROM AUTHOR]

The complex formation of nickel(II) and copper(II) ions with 4,4′-bipyridine in non-aqueous solvents—dimethyl sulfoxide, dimethylformamide, dimethylacetamide, acetonitrile, ethanol and methanol was studied by UV-Vis absorption spectroscopy. Stability constants of the resulting complexes were calculated. [ABSTRACT FROM AUTHOR]

Recently, it has become more and more obvious that the use of the unique physical properties of graphene is practically inexhaustible. In our work, we used the surface of oxygen-free graphene sheets to stabilize the AlClPc complex and prevent its agglomeration. A sonochemical method was developed for the preparation of stable suspensions of oxygen-free graphene in a DMF-aqua mixture, the composition and morphology of which were characterized using TEM, DLS, and Raman. Also, a method for the synthesis of hybrid structures based on AlClPc and graphene was developed, and new electrons interactions in them were determined by using of UV-VIS absorption spectroscopy. It was proved that these interactions are due to the graphene participation in surface complex with charge transfer. Graphene also prevents the agglomeration of the AlClPc complex, which is especially valuable for using the synthesized structure in biomedical research. The results obtained show how the use of molecular design techniques makes it possible to create new platforms for vector drag delivery and early diagnosis. [ABSTRACT FROM AUTHOR]

In this paper, density functional theory (DFT) and time-dependent density functional theory (TDDFT) are used to study the complexation characteristics CdTe QDs with four different capping agents, i.e. 3-mercaptopropionic acid (MPA), reduced glutathione (GSH), 1-thioglycerol (TG) and 2-mercaptoethanesulfonate (MES). The properties of these complexes are analyzed by the complexation free energies, bond lengths, LOL, ADCH charges, frontier molecular orbitals and the UV–Vis absorption spectra. The results indicate that the four capping agents could form stable complexes with CdTe QDs. Whether the four capping agents interact with (CdTe)6 or (CdTe)9, MES has the strongest complexation ability with CdTe QDs and the MES-complexes are the most stable. For (CdTe)6, A2-MES is the most stable configuration. The complexation free energy and bond length of A2-MES are − 74.50 kcal/mol and 2.461 Å, respectively. When (CdTe)9 as substrate, A4-MES is the most stable configuration and corresponding complexation free energy is − 100.97 kcal/mol, which is followed by A4-MPA (− 57.75 kcal/mol) and A3-TG (− 60.20 kcal/mol), while A4-GSH (− 44.47 kcal/mol) is the weakest. Moreover, the electron amount transferred from MES to CdTe QDs is the most, and the ADCH charge value is 1.47 e. The absorption intensity of UV–visible light after complexation is also the largest. This is consistent with the result of the complexation free energy. Thus, it can be seen that the complexation abilities of four capping agents are in order of MES > MPA≈TG > GSH. [ABSTRACT FROM AUTHOR]

Martensitic transformations are the first-order crystal-to-crystal phase transitions that occur mostly in materials such as steel, alloys and ceramics, thus having many technological applications. These phase transitions are rarely observed in molecular crystals and have not been detected in protein crystals. Reversibly switchable fluorescent proteins are widely used in biotechnology, including super-resolution molecular imaging, and hold promise as candidate biomaterials for future high-tech applications. Here, we report on a reversibly switchable fluorescent protein, Tetdron, whose crystals undergo a photo-induced martensitic transformation at room temperature. Room-temperature X-ray crystallography demonstrates that at equilibrium Tetdron chromophores are all in the trans configuration, with an ∼1:1 mixture of their protonated and deprotonated forms. Irradiation of a Tetdron crystal with 400 nm light induces a martensitic transformation, which results in Tetdron tetramerization at room temperature revealed by X-ray photocrystallography. Crystal and solution spectroscopic measurements provide evidence that the photo-induced martensitic phase transition is coupled with the chromophore deprotonation, but no trans–cis isomerization is detected in the structure of an irradiated crystal. It is hypothesized that protein dynamics assists in the light-induced proton transfer from the chromophore to the bulk solvent and in the ensuing martensitic phase transition. The unique properties of Tetdron may be useful in developing novel biomaterials for optogenetics, data storage and nanotechnology.

G-quadruplex DNAs (G4 DNAs) are emerging as promising anticancer drug targets due to their presence in the promoter regions of different oncogenes. Utilizing different spectroscopic techniques like UV–Vis absorption titration, thermal denaturation, spectrofluorimetric titration, fluorescence displacement assay, Job plot analysis, circular dichroism spectroscopy and also, molecular docking studies, the interaction of a synthetic nitro-flavone, 2-(4-Nitrophenyl)-4H-chromen-4-one (4NCO), with various G4 DNA structures (c-KIT1, c-KIT2, c-MYC, h-TELO and VEGF) was elucidated. We also investigated the effect of 4NCO on different cancer cell lines. Effect on cell morphology, DNA damage, cell cycle arrest, viability and mode of cell death were evaluated in A375 melanoma cells. Our findings indicated that 4NCO showed preferential binding towards c-MYC promoter G4 to stabilize it with a binding constant (Kb) value of the order of ~105 M−1 and binding stoichiometry of ~1:1. It also showed a unique dual binding mode when bound to c-MYC with a lower binding free energy having multiple strong interactions when compared to the other G4s. In cells, it induced DNA damage resulting in cell cycle arrest at G1/S phase until 24 h, after which, cells strictly underwent apoptosis. It also showed a preferential cytotoxicity towards the A375 melanoma cells. The ability of 4NCO to stabilize the c-MYC G4 to possibly suppress the over-expression of MYC was responsible for inhibition of proliferation of these cells. Hence, these results present a novel finding on the effectiveness of the nitro-flavone derivative 4NCO as a potent ligand for c-MYC G4 DNA thereby, providing possibilities of its use in cancer therapy for regulating the oncogene expression in cancer cells.

Dissolved organic matter (DOM) in sediment pore water plays a key role in lake water quality, complexation of the contaminants, biogeochemical cycles, and even climate. To better understand the vertical dynamics and characteristics of DOM among pore water profiles, we investigated concentrations, chemical structures, and benthic fluxes of DOM in plateau lake sediments via stoichiometric analysis, ultraviolet–visible (UV–vis) absorption, three-dimensional fluorescence matrix spectroscopy (EEMs), and parallel factor model (PARAFAC). The results revealed that dissolved organic carbon (DOC), concurrent with chromophoric DOM (CDOM) and fluorescent DOM (FDOM), tended to accumulate in the anaerobic deeper layers. These trends also demonstrated a good agreement with the ammonium nitrogen (NH4+-N) concentration, implying that the pathway of DOM dynamics was closely related to the redox state. The EEMs-PARAFAC model revealed that DOM in pore water mostly consisted of two terrestrial humic-like components (average contribution:> 60%) followed by microbial and tryptophan-like components, respectively. Terrestrial humic-like components were relatively stable, and their abundance was positively correlated with the FDOM level (p

Ultraviolet-visible absorption spectroscopy is widely used to monitor water quality, and rapid optical signal detection is a key technology in the process of spectrum measurement. In this paper, an ultrafast spectrophotometer system that can achieve spectrum data acquisition in a single flash of the xenon lamp (within 200 ns) is introduced, and a real-time denoising method for the spectrum is implemented on a field programmable gate array (FPGA) to work cooperatively with the nanosecond spectrum acquisition system, in order to guarantee the quality of the spectrum signals without losing running speed. The hardware of the data acquisition and processing system are constructed on a Xilinx Spartan 6 FPGA chip and its peripheral circuit, including an analog to digital converter and a complementary metal-oxide-semiconductor transistor (CMOS) sensor’s diver circuit. An oversampling method that is suitable for the CMOS sensor’s output is proposed, which works on the CMOS sensor’s dark current noise and readout noise. Another moving-average filter method is designed adaptively, which works on the low-frequency component to filter out the residual spectrum noise of the spectrum signal. The implementation of the filter on the FPGA has been optimized by using a pipelined structure and dual high-speed random-access memory (RAM). As a result, the CMOS linear image sensor successfully captured the spectrum of xenon flash light at the readout clock frequency of 500 kHz and the processing manipulation to the full UV-Vis spectrum data was accomplished at a sub-microsecond speed performance. After the digital filter and oversampling technology were implemented, the coefficient of variation of the measurements reduced from 9.57% to 1.74%, while the signal noise ratio (SNR) of the absorption spectrum increased nine times, compared to the raw data of the CMOS sensor’s output. The tests towards different analyte samples were conducted, and the system shows good performance on distinguishing different concentrations of different analyte solutions on both ultra-violet and visible spectrum bands. The present work showcases the potential of the CMOS sensor’s technique for the fast detection of contaminated water containing nitrate and organic compounds.

We have implanted xZnF2–(20-x)ZnO–40As2O3–40TeO2 (x = 4 and 20 mol%) glasses with nitrogen ions at different doses. The glass samples were characterized by Rutherford backscattering spectrometry for the concentration depth profiles of the implanted atoms, by SEM analysis for surface morphology, and also by UV–vis absorption spectroscopy. It was observed that in both the glass systems, there is an increase in the values of penetration depth R, projected range Rp, and straggle ΔRp as the N+ implantation dose grows from 5 × 1016 to 5 × 1017 ions/cm2. Scanning electron micrographs show a considerable change in the surface topography between the unimplanted and nitrogen-implanted regions. After nitrogen ion implantation, the transmittance was found to decrease while the absorption edge shifts towards higher wavelength with the increase in the nitrogen implantation doses in both the glass systems. The observed reduction in optical band gap in the both the glass systems can be attributed to the effect of band tailing due to the defects produced during nitrogen implantation. [ABSTRACT FROM AUTHOR]

We describe a synthetic method for the synthesis of merocyanine dyes containing a bridge with three conjugated double bonds. This method consists of two successive condensation reactions. The first one is made between CH-acidic indane-1,3-dione acceptor units and an appropriate ketone (here acetone or hexan-2-one). The extended acceptor thus obtained is condensed with an aldehyde in the next step. The dyes show high tinctorial strength due to intense absorption bands at wavelengths between 500 and 750 nm. [ABSTRACT FROM AUTHOR]

A series of quadruple perovskites Ca 1 +x Cu 3 -x Ti 4 O 12 was scanned by different spectroscopic and microscopic techniques. X-ray powder diffraction pattern analysis revealed that the system transformed from a monophasic (x = 0.0, 0.1 and 0.2) to biphasic (x = 0.5 and 1.0) on Ca2+ - substitution. The completely different grain morphology and the distinct signature of the UV–visible absorption band and Raman scattering peak reflect this finding well. The defects arise mainly because of the mismatch between ion and site radii. The results of positron annihilation spectroscopy to study the nature of the defects are consistent with the proposed defect-rich sample history. There are many vacancies-type defects, whose size and concentration could be characterized through the measured positron lifetimes and coincidence Doppler broadening. The results show that for x = 0.1 itself, a secondary phase may be formed. The structure-property and property-property correlations are studied. [ABSTRACT FROM AUTHOR]

Common ultrasonication and centrifugation techniques could be utilized for dispersion of carbon nanotubes in solvents. However, there are few studies investigating the effect of concentration of species on stability of surfactant modified suspensions focusing on specific dispersants. Therefore, in this study, UV–Vis absorption spectroscopy, sedimentations tests, zeta (ζ) potential and dynamic light scattering analyses (DLS) were used as tools to estimate the optimal surfactant to multi walled carbon nanotubes (MWCNTs) weight ratio in stable centrifuged suspensions. MWCNTs colloids were prepared via addition of sodium dodecylbenzene sulfonate (SDBS) with ultrasonication and centrifugation in isopropyl alcohol (IPA). Coupling information gathered from overlapped absorption spectra and weighed dried sediments enabled estimation of MWCNTs concentrations in centrifuged suspensions (supernatant). By utilizing sediments weight and zeta potential observations, optimum SDBS/MWCNTs weight ratios were calculated. The results have shown that the SDBS/MWCNTs ratio should be 9 or higher in supernatants in order to obtain stable suspensions. It was also observed that increasing SDBS/MWCNTs concentrations over 9 in supernatants gradually decreased the zeta potentials of studied suspensions. Higher SDBS/MWCNTs ratios, also decreased settling velocities that were attributed to increased viscosity of supernatants. In addition to overlapping spectra technique, which relies on utilization of spectra related to centrifuged and uncentrifuged suspensions only for quantitative analysis, differential UV–Vis spectra were also utilized for the assessment of SDBS/MWCNTs ratios in supernatants. Presence of SDBS in supernatants (prepared by removing contribution of MWCNTs by using COOH modified MWCNTs' UV–Vis absorption spectrum) exhibited an unexpected hyperchromic shift in maximum wavelength in spectra leading to misleading estimations of surfactant concentrations. Image 1 [ABSTRACT FROM AUTHOR]

Tetracycline is one of the most commonly used antibiotics in a wide range of antibacterial drugs. Self-association of drugs (e.g. antibiotics) causes problems, such as increasing toxicity and reducing penetration of drugs through cell membranes. In this study, the self-association process of tetracycline was investigated experimentally and theoretically in aqueous, ethanol, and salt solutions. Spectroscopy studies showed that the self-association process occurred in salt solution at lower concentrations of tetracycline in comparison with the other two solutions. However, the presence of ethanol led to a delay in the self-association process. The self-association constants of tetracycline were obtained by using experimental values. Moreover, the analysis of the number of clusters and solvent accessible surface area were carried out by molecular dynamics (MD) simulations. The MD results clarified that the tetracycline self-association process happened earlier in salt solution compared to the others through forming the larger clusters by the hydrophobic interactions, whereas the presence of ethanol caused a reduction in the self-association process and the cluster populations through weakening the hydrophobic interactions. Furthermore, the type of the involved interactions in the formation of the tetracycline clusters was investigated by RDG analysis. The obtained results revealed that van der Waals interactions possessed a fundamental influence on the formation of tetracycline clusters. [ABSTRACT FROM AUTHOR]

Electronic structures of four pyrene-derived N-heterocyclic carbene complexes of platinum(II) and gold(III) bearing cyclometallated 2,6-diphenylpyridine have been investigated theoretically. The structures of all complexes in gas phase have been first optimized. Different functionals and basis sets have been tested to find the best theoretical method. The results show that B3PW91 (LANL2DZ/6-31G*) combination give the best description of the molecules as compared with experimentally determined structural features. Using the calculation data from that best functional and mixed basis set combination, frontier molecular orbitals of the complexes have been examined. To gain understanding on the nature of electronic transitions in the UV-vis absorption spectra of the compounds, TD-DFT calculations have been carried out. A details analysis of the vertical excitation reveals that the nature of all the vertical electronic transitions in the complexes. Notably, the lowest energy transitions are πcb + dPt → (for Pt1 and Pt2) and πCNC → dAu + (for Au1 and Au2) charge transfer in nature. A sharp contrast in lowest energy triplet excited state for d8‑squared planar Au1 and Pt1 has been demonstrated. While no contribution from gold(III) d orbital to the SOMO and SOMO – 1 orbital of Au1, there is significant contribution of platinum(II) dyz orbital in the SOMO – 1 orbital of Pt1, suggesting possible interaction of this singly occupied orbital with radical of π-symmetry substrates. [ABSTRACT FROM AUTHOR]

In this contribution, polyvinyl pyrrolidone capped copper nanoclusters (PVP‐Cu NCs) were synthesised through a one‐pot route possessing the advantages of rapidness and environmental friendliness. Also, the optical characteristics of the as‐prepared Cu NCs were characterised using fluorescence spectroscopy, UV–vis absorption spectroscopy. The structure and composition were studied through Fourier transform infrared, transmission electron microscopy, X‐ray photoelectron spectroscopy. It exhibited good water solubility, excellent photo stability, and resistance to sodium chloride. The Cu NCs revealed blue fluorescence and displayed excitation‐dependent fluorescence characteristics. More importantly, the fluorescence intensity of PVP‐Cu NCs was linearly quenched in the range of 5–80 μM (concentrations of fluazinam) and the detection limit was 0.98 μM. Finally, the fluorescence sensor was successfully employed to detect fluazinam in natural water samples. [ABSTRACT FROM AUTHOR]

[Display omitted] • For the first time, we established machine learning models that can predict the formation behavior of carotenoid aggregates. • New ultra-weakly coupled β-carotene J-aggregates were synthesized and have absorption bands up to 700 nm, different from all the β-carotene J-aggregates reported previously. • Aromatics with different alkyl chain length facilitate the formation of ultra-weakly coupled β-carotene J-aggregates. Carotenoid aggregates are omnipresent in natural world and can be synthesized in hydrophilic environments. Despite different types of carotenoid aggregates have been reported hitherto, the way to predict the formation of carotenoid aggregates, i.e. H- or J-aggregates, is still challenging. Here, for the first time, we established machine learning models that can predict the formation behavior of carotenoid aggregates. The models are trained based on a database containing different types of carotenoid aggregates reported in the literatures. With the help of these machine learning models, we found a series of unknown types of β-carotene J-aggregates. These novel aggregates are ultra-weakly coupled and have absorption bands up to 700 nm, different from all the carotenoid aggregates reported previously. Our work demonstrates that the machine learning is a powerful tool to predict the formation behavior of carotenoid aggregates and can further lead into the discovery of new carotenoid aggregates for different applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Monoanionic, tridentate N^N^O- ligands (RL) bearing strongly absorbing π-extended phenanthridine (benzo[ c ]quinoline) donors have been prepared and used to form magnetically active pseudo-octahedral Fe(III) complexes. • Site-selective benzannulation from quinoline to phenanthridine leads to counter-intuitive blue-shifts to the absorption profile of Fe(III) pseudo-octahedral Schiff-base style complexes, with a long absorptive tail that extends well into the visible region, only attenuating close to 850 nm. • Substitution of the phenanthridine ligand arms can alter the magnetic response to temperature, yielding gradual though incomplete spin-crossover for a methoxy-substituted variant. Paramagnetic complexes which can undergo spin crossover between different magnetic states that also strongly absorb light are highly attractive for the pursuit of optical magnetic technologies. Against this backdrop, we prepared a library of Fe(III) complexes ligated by monoanionic, tridentate N^N^O- ligands (RL : (2- R 1-(4-imino-methyl)-phenanthridinyl)]-5- R 2-phenolate where R 1 = t Bu, F, OMe, R 2 = H or R = t Bu, R 2 = t Bu) bearing strongly absorbing π-extended phenanthridine (benzo[ c ]quinoline) donors: [Fe(tBuL) 2 ]PF 6 , [Fe(tBuL tBu) 2 ]PF 6 , [Fe(FL) 2 ]PF 6 , and [Fe(OMeL) 2 ]PF 6. The solid-state structures of three of the series were determined using single-crystal X-ray diffraction, confirming pseudo-octahedral coordination geometries. Electronic absorption spectra shows strong absorbances near 340 nm and 415 nm for the series due to π-π* and ligand-to-metal-charge-transfer (LMCT) transitions, respectively, along with a long absorptive tail that extends well into the visible region, only attenuating close to 850 nm. Magnetic measurements in the solid-state (SQUID magnetometry) and in solution (Evans' Method) revealed the influence of ligand substituents. For example, the magnetic moment of [Fe(FL) 2 ]PF 6 in the solid-state remains more or less constant at a χ m T ∼ 2.3 over a large temperature range (25–300 K) indicative of a mixed spin configuration that is maintained in solution at ambient temperature, while [Fe(tBuL) 2 ]PF 6 and [Fe(tBuL tBu) 2 ]PF 6 only reach values of ∼1.5 at higher temperature. In comparison, the χ m T of [Fe(OMeL) 2 ]PF 6 undergoes a much more abrupt drop upon cooling, from ∼2.5 to below 0.5 at 100 K, consistent with spin-crossover type behavior. [ABSTRACT FROM AUTHOR]

Solar ultraviolet (UV) radiation exhibits a significant degradation for dissolved organic matter (DOM) in natural water ecosystems. However, research on photodegradation process of terrestrial components (e.g., humic-like substances) of DOM are limited due to drastic water dilution and rapid degradation. Here, photochemical degradation of terrestrial soil DOM with abundant humic-like substances from different land use were investigated by utilizing spectral technologies. Simulated UV radiation caused obvious losses on concentration, component structures, and fluorescence characteristic of soil DOM samples. The correlations between absorption specific parameters (a280, SUVA254, and SR) and dissolved organic carbon (DOC) were especially pronounced (p < 0.05), which could be used as valid indicators to determine changes in DOM composition and molecular size during photobleaching process. The decreases of DOM fluorescence intensity were corresponded to first-order kinetic and half-life reactions. The greatest reduction on fluorescence intensity (31.56–81.97%) belonged to peak C (i.e., humic-like substances). Overall, DOM from forest and grass soil ecosystems was more easily photochemical degraded than anthropogenic soil DOM. Enhancive contribution of fresh DOM formed by photodegradation increased autochthonous characteristic and bioavailable nutrition by increasing biological index (BIX) values and ammonia nitrogen (NH4+–N) concentration. The slight microbial decomposition effects on DOM happened in unsterilized dark condition. Our findings provided insights for understanding the rapid photodegradation processes of composition and structure of terrestrial DOM. [ABSTRACT FROM AUTHOR]

The cation-induced dimerization of tetra-(15-crown-5)-substituted Al(III) phthalocyaninate with Na+, K+ and Rb+ salts in solution has been studied by 1H NMR. It has been demonstrated that two types of supramolecular dimers coexist in solutions, which is consistent with the existence of both the monomeric and oxygen-bridged dimeric forms of the initial Al(III) complex. With the use of mass spectrometry (MALDI-TOF and HR-ESI), it has been shown that Al(III) monophthalocyaninate [(OH)AlR4Pc] forms supramolecular dimers {[M4(XAlR4Pc)2]4+(X−)4}, whereas Al(III) μ-oxodiphthalocyaninate [(AlR4Pc)2(μ-O)] forms oxygen-bridged supramolecular dimers {[M4(XAlR4Pc)2(μ-O)]2+(X−)2}. [ABSTRACT FROM AUTHOR]

The electrochemistry of ruthenium (Ru) etching in acidic solution containing cerium (IV) (Ce4+) has been investigated. Voltammograms were measured to determine the onset potentials of metal stripping and cathodic reduction of the oxidizing agent. Etch rates of blanket thin films of chemical vapour deposited Ru were measured using Rutherford backscattering spectrometry. Sheet resistance measurements of a thickness range of wet-chemically etched and as-deposited Ru thin films are compared. X-ray photoelectron spectroscopy was used to characterize post-etching residues. Using atomic force microscopy, the surface morphology of Ru after etching and removal of residues by rinsing with water or acid and ultrasonic agitation was studied. Compatibility of low-k dielectric material with the etchant has been assessed using Fourier transform infrared spectroscopy. UV–vis absorption spectroscopy was used to study the stability and absorption features of various Ce4+ compounds in sulphuric and methane sulphonic acid. Additionally, mixtures containing Ce4+ and Ce3+ were analyzed. In situ measurements during Ru etching show the conversion of the oxidizing agent to Ce3+. [ABSTRACT FROM AUTHOR]

Abstract A new and straightforward optical sensor for the colorimetric determination of adenosine (AD) in human urine samples was developed. The sensor comprised silver nanoparticles (AgNPs) as colorimetric elements and anti-AD aptamer (AP) as a recognition probe. In a solution containing AD and high concentration of NaCl, due to the unique binding of AD with AP, the aggregated metal nanomaterials dispersed in the solution, and the color intensity of the solution was changed accordingly. The absorbance of the solution was monitored for AD quantification. The method was applicable for the determination of AD in the concentration range of 60–280 nM with the detection limit of 21 nM. The relative standard deviation ranged from 4.8 to 8.8% for six replicates. The method showed excellent selectivity toward AD checked over some probable interfering compounds. To investigate the performance of AgNPs, the analytical characteristics of the method including linear range, detection limit, selectivity, and precision were compared with those obtained by a common AuNPs-based aptasensor. The reliability of the method was further ascertained for the detection of AD in urine samples of two lung cancer patients with percentage recoveries in the range of 98–107%. Graphical Abstract Unlabelled Image Highlights • Unfunctionalized-aptamer and unmodified AgNPs were used to prepare aptasensor. • Detection was based on the aggregation degree of AgNPs. • The aptasensor was rapidly prepared in 10 min, without long immobilization time. • Adenosine was determined in urine samples by the colorimetric aptasensor. [ABSTRACT FROM AUTHOR]

In addition to the donor-acceptor nano phases, the intermixed phase within the organic blends is crucial for the photovoltaic performance and stability of the bulk-heterojunction organic solar cells (OSCs). Here, the intermixed phase of a representative M-PhS:BTP-eC9 all-small-molecule organic solar cell was investigated by a concentration-dependent ultraviolet-visible (UV-vis) absorption spectroscopy method, where a shift of the absorption maximum wavelength was measured for the acceptor component with the increase of the acceptor concentration. The blend ratios of the acceptor to the donor in the intermixed phase, corresponding to the critical concentration for the formation of the acceptor nanophase ( C AP ), were determined to be 0.35, 0.20, and 0.15 for the as-cast, thermal annealing (TA), and the combined TA and solvent vapor annealing films. These results indicated that M-PhS and BTP-eC9 are kinetically well intermixed during spin coating, whereas TA and the following solvent annealing promote the crystallization of BTP-eC9 molecules out of the intermixed phase. The photovoltaic performance of the M-PhS:BTP-eC9 cells with different blend ratios was investigated. The formation of the BTP-eC9 nano phase in the blend film leads to stable V OC and fast increased J SC , which can be understood by the reduction of bimolecular charge recombination and the formation of electron transporting pathways within the photoactive layer. Similarly, the critical concentration for the formation of the donor phase was estimated to be 0.15 by measuring the stabilized V OC and increased J SC values of the cells with different donor blending ratios. More importantly, after a fast "burn-in" thermal degradation, the M-PhS:BTP-eC9 cell showed excellent thermal stability aging at 85 °C for over 1128 h, which is in good accordance with the unchanged intermixed phases measured by the UV-vis spectra of the annealed films. The current work demonstrates the feasibility of the spectroscopy method to investigate the intermixed phases for organic bulk-heterojunction solar cells and proves that all-small-molecule solar cells can be intrinsically very stable.

Prostate apoptosis response-4 (Par-4) tumor suppressor protein has gained attention as a potential therapeutic target owing to its unique ability to selectively induce apoptosis in cancer cells, sensitize them to chemotherapy and radiotherapy, and mitigate drug resistance. It has recently been reported that Par-4 interacts synergistically with cisplatin, a widely used anticancer drug. However, the mechanistic details underlying this relationship remain elusive. In this investigation, we employed an array of biophysical techniques, including circular dichroism spectroscopy, dynamic light scattering, and UV-vis absorption spectroscopy, to characterize the interaction between the active caspase-cleaved Par-4 (cl-Par-4) fragment and cisplatin. Additionally, elemental analysis was conducted to quantitatively assess the binding of cisplatin to the protein, utilizing inductively coupled plasma-optical emission spectroscopy and atomic absorption spectroscopy. Our findings provide evidence of direct interaction between cl-Par-4 and cisplatin, and reveal a binding stoichiometry of 1:1. This result provides insights that could be useful in enhancing the efficacy of cisplatin-based and tumor suppressor-based cancer therapies., (© 2023 The Authors. Protein Science published by Wiley Periodicals LLC on behalf of The Protein Society.)

Graphical abstract Abstract Triton X-100 (TX-100) is the most common surfactant used to split viruses during the production of influenza split-virus vaccines. It is a mild surfactant not known to denature the viral proteins; this property makes TX-100 useful for maintaining antigen conformational structure, and, as an added benefit, for partially stabilizing vaccine formulations against protein aggregation. Despite its benefits, TX-100 needs to be filtered out after virus splitting has been achieved, due to its toxicity in large quantities. Accordingly, residual TX-100 presence in vaccine formulations has implications for both formulation stability and safety, necessitating both accurate screening during processing to guide decision-making about filtration repeats and accurate quantitation in the final product. Accurate HPLC-based methods are used successfully for the latter but their use for routine screening during processing is far from ideal because they often require extensive sample preparation and are fairly slow, complicated and costly. Here, "deconstruction" of UV–Vis absorption spectra into components corresponding to different absorbing "species" is demonstrated as a novel and viable method for routine TX-100 screening in vaccine samples from different industrial processing steps. This method is fairly accurate and, more importantly, preparation-free, rapid, simple/user-friendly and comparatively inexpensive. It is evaluated in depth in terms of applicability conditions, limitations and potential for high-throughput adaptation as well as generalization to other complex biopharmaceutical formulations. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • All three hormones form stable complexes with promazine in solution. • Complexes are formed by hydrogen bonding or π-π∗ interactions. • Computational methods can be used for prediction of charge transfer properties. Abstract Charge transfer complexes formed by electron transfer processes are important components of many biochemical processes. Donor-acceptor complex formation between promazine and dopamine, serotonin and melatonin was investigated using experimental and computational methods. UV–Vis absorption, fluorescence spectroscopy and cyclic voltammetry measurements were carried out to investigate the intermolecular interactions and donor-acceptor properties. Geometry optimizations were completed at ωB97XD/6-31G(d,p) level and electronic transitions were performed by the time-dependent density functional theory with CAM-B3LYP, B3LYP, and ωB97XD functionals using 6-311++G(d,p) basis set. Complex formation with promazine is in the order as melatonin > serotonin > dopamine in water especially by H-bond formation. Experimental and calculated values for UV–Vis absorption spectra and HOMO, LUMO energies were compared and found in agreement in water. Serotonin was determined as the best donor among studied molecules forming H-bond and π-π∗ interactions with promazine. Investigated complexes may be useful for the design of organic-biological hybrid components acting as donor-acceptor systems. [ABSTRACT FROM AUTHOR]

The speciation of uranium(VI) extracted by a molecular extractant N,N,N′,N′ -tetra( n -octyl)diglycolamide (TODGA) and a hydrophobic ionic liquid (IL), namely 1-butyl-3-methylimidazolium bis (trifluoromethanesulfonyl)imide [C 4 mim][Tf 2 N], mixture from acidic nitrate media in 1,2-dichloroethane (DCE), and, for comparison, with only TODGA dissolved in DCE or IL has been studied by UV–vis and EXAFS spectroscopy. Our results confirm that the extraction in the conventional system occurs via a common solvation mechanism, at high acidity the extracted complex was identified as [UO 2 (NO 3 ) 2 (TODGA)]. The addition of hydrophobic bistriflimide anions (Tf 2 N − ) in the aqueous phase or IL in the organic phase results in a formation of another uranyl complex, in which two tridentate TODGA ligands directly coordinate metal cation and two NO 3 – and/or Tf 2 N − anions are expulsed in the outer sphere and act as charge balancing ions. When pure IL is used as diluent for TODGA ligand, the extracted uranyl complex has the same composition and stoichiometry as in the previous case, [UO 2 (TODGA) 2 ] 2+ . [ABSTRACT FROM AUTHOR]

We combined Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) and mass spectrometric analysis of stable carbon isotopes, a traditional method for tracking DOM sources, to investigate the variation in the complexity of water samples collected along a salinity gradient in Delaware Bay in March and August 2014. Detailed analyses of optical properties (ultraviolet and visible (UV–Vis) absorbance and excitation-emission matrix (EEM) fluorescence spectroscopy) were carried out. Results from statistical parallel factor analysis (PARAFAC) of EEM data were also used to track and further constrain fluorescent DOM (FDOM). Optical analyses and FT-ICR-MS data showed large differences between late winter and summer conditions, and the stable carbon isotopic composition was more variable in summer than in late winter. Although terrestrial inputs of DOM are evident at low salinities in both seasons, our data suggest that a significant source of FDOM, from either in situ water column production or from benthic aquatic or semi-aquatic plant communities, contributes DOM to low and mid-salinity waters in Delaware Bay during summer but not in late winter. [ABSTRACT FROM AUTHOR]

Currently green and translucent variscites have been discovered near the turquoise ore body in the Ma'anshan mine. Some variscites can achieve gem grade. The testing methods of Electron Probe Microanalysis (EPMA), X-ray Powder Diffraction (XRD) analysis, Scanning Electron Microscope (SEM), Fourier Transform Infrared (FTIR) absorption spectroscopy and Ultraviolet-Visible (UV-Vis) absorption spectroscopy were conducted to analyze the chemical composition, mineral structure, microstructure, and spectroscopy features of variscites. According to the study of occurrence status of water, the color mechanism of variscite was further studied. The result of chemical composition by EPMA analysis shows that variscite from Ma'anshan is mainly composed of Al and P with a small amount of Fe and V. The XRD pattern shows variscite is composed of pure variscite mineral. Furthermore, the infrared absorption spectroscopy analysis shows variscite is hydrated phosphate based upon the formula AlPO4·2H2O, which has crystalline water and hydroxyl connected with Al3+(Fe3+). The vibration mode and frequency of H2O, OH- and PO43- determine the infrared spectrum's main feature of variscite samples. The hydroxyl stretching vibrations appear at 3581 cm-1 and the crystalline water stretching vibrations appear at 3382 and 3253 cm-1. Correspondingly, their bending vibrations appear at 910, 842 and 796 cm-1 from the infrared absorption spectroscopy. The phosphate stretching vibrations appear at 1056 cm-1 while the bending vibrations appear at 592 cm-1 with other spilt bands. The observation by SEM shows that the variscite crystals are stacked by short column and short plate as aggregates. One variscite crystal shows the feature of an orthorhombic system. The absorption spectrum at 639 nm in the UV-VIS spectroscopy was caused by Fe3+ and V3+ d-d electronic transition. The absorption spectrum at 300 nm, 423 nm and 864 nm are assigned to Fe3+ d-d electronic transition. Fe3+ and V3+ both cause the green colour of variscite. The modern analytical techniques of FTIR and UV-Vis spectroscopy analysis were used in the study based on the chemical composition and mineral structure analysis, which determined the information of mineral structure, existing form of water and metal ion of variscite from Ma'anshan in order to further study the color-forming mechanism of variscite.

Pure and Mg-doped ZnO thin films have been fabricated by a sol-gel spin coating method. The as prepared films were annealed at 400 °C. The structural, optical, morphological and luminescent characteristics were studied by using X-ray diffraction (XRD), diffuse reflectance (DR), scanning electron microscopy and photoluminescence spectroscopy techniques. XRD results show the polycrystalline behavior of deposited films without any impurity or formation of extra phase. DR spectra exhibit the blue shift in the absorption edge gap after Mg doping. It has been observed that the band-gap of the fabricated films rises with the increase in the Mg doping. The obtained results have been explained by existing literature and a good comparative study has been made. [ABSTRACT FROM AUTHOR]

Plasma synthesized 2-furaldehyde (PPFDH) amorphous polymer thin films of varying thicknesses were prepared in optimum conditions by a capacitively coupled parallel plate glow discharge reactor at room temperature. The structure, morphology, composition and optical properties of deposited PPFDH thin films have been investigated using X-Ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Scanning electron microscopy (SEM), Energy dispersive X-Ray spectroscopy (EDS), as well as Ultraviolet–visible (UV–vis) absorption spectroscopy. XRD results confirmed the amorphous nature of the films. The smooth and uniform nature of the PPFDH thin films were observed by SEM images. FTIR analyses of monomer FDH and PPFDH thin films show that structural rearrangement has occurred due to the synthesis process taking place in the chemical structure. IR stretching bands obtained from DFT calculations of the optimized structures of monomer and polymer of 2-furaldehyde are in good agreement with the experimental results. UV–vis absorption spectra in transmittance as well as reflectance mode was utilized to compute absorption coefficient, allowed direct and indirect transition energy gaps, band edge sharpness, Urbach energy, steepness parameter, extinction coefficient, and dispersion and oscillator energy. The oscillator strength, moments of optical spectra, refractive index at infinite wavelength, high frequency dielectric constant, average oscilator strength, complex refractive index, dissipation factor, optical conductivity and skin depth were also determined by using measured UV–vis transmittance and reflectance spectra. [ABSTRACT FROM AUTHOR]