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Removing excess phosphate from environmental water is extremely important to reduce eutrophication. In this study, cellulose nanocrystals (CNCs) were utilized as biological templates, and the SA-La...

Efficient incorporation of large-mesoporous silica materials with the film structure to fabricate hybrid film materials has been promising for water treatment. The modified large-mesoporous silica films possessed superior adsorbability, but the poor mechanical behavior hampered the application of adsorbents. We proposed the fabrication of La modified rGO/silica mesoporous films for efficient phosphate removal to deal with this problem. Consider the problem of plugging of mesopores, La/Si molar ratio of 1/10 was a conventionally reported loading ratio in the literatures. In this paper, the film materials also retained pore size (19.97 nm) comparable with that of the pristine large-mesoporous silica films (20.53 nm) when the La/Si molar ratio was 1/5. In the adsorption experiments, the maximum phosphate capacities achieved 55.045 mg g−1. And multi-adsorption mechanisms were confirmed by the results of analysis. The formation of rod-like crystal LaPO4 was the main pathway in the adsorption process. The film material might create a new way for phosphate removal.

The Kresling truss structure, derived from Kresling origami, has been widely studied for its bi-stability and various other properties that are useful for diverse engineering applications. The stable states of Kresling trusses are governed by their geometry and elastic response, which involves a limited design space that has been well explored in previous studies. In this work, we present a magneto-Kresling truss design that involves embedding nodal magnets in the structure, which results in a more complex energy landscape, and consequently, greater tunability under mechanical deformation. We explore this energy landscape first along the zero-torque folding path and then release the restraint on the path to explore the complete two-degree-of-freedom behavior for various structural geometries and magnet strengths. We show that the magnetic interaction could alter the potential energy landscape by either changing the stable configuration, adjusting the energy well depth, or both. Energy wells with different minima endow this magneto-elastic structure with an outstanding energy storage capacity. More interestingly, proper design of the magneto-Kresling truss system yields a tri-stable structure, which is not possible in the absence of magnets. We also demonstrate various loading paths that can induce desired conformational changes of the structure. The proposed magneto-Kresling truss design sets the stage for fabricating tunable, scalable magneto-elastic multi-stable systems that can be easily utilized for applications in energy harvesting, storage, vibration control, as well as active structures with shape-shifting capability.

In this work, a novel Z-scheme CdIn2S4 nano-octahedron/BiOCl nanosheet (CIS/BOC) heterostructure was successfully designed and synthesized via a facile in-situ hydrothermal process, where the CdIn2S4 nano-octahedra grew on the surfaces of tiny BiOCl nanosheets in a face-to-face way. The structure, morphology and optical properties of as-prepared samples were characterized through various technologies. The photocatalytic activities were systematically evaluated by the degradation of methyl orange (MO), tetracycline hydrochloride (TCH) and rhodamine B (RhB) under simulated solar light irradiation. The degradation results displayed that all CIS/BOC composites exhibited significantly enhanced photocatalytic activities toward MO degradation in comparison with the bare CdIn2S4 and BiOCl. Simultaneously, the obtained CIS/BOC-2 with 6 wt.% BiOCl nanosheets loaded possessed the optimal photocatalytic performance, and its rate constant was about 3.6 and 2.59 times as high as those of bare CdIn2S4 and BiOCl. Furthermore, the CIS/BOC-2 nanocomposite with superior photostability and repeatability also presented high photocatalytic activities for the removal of both antibiotics (TCH) and dyestuff (RhB). The unique Z-scheme face-to-face heterostructure with intimate contacted interface in CIS/BOC-x nanocomposites provided more charge transfer nanochannels, shortened the migration distance and boosted the separation of photoinduced charge carriers, resulting in the excellent photocatalytic activities. Our study may provide a promising strategy to develop and synthesize other Z-scheme face-to-face composite photocatalysts with good photocatalytic performance.

The dynamic characteristics of the sliding surface will affect the dynamic properties of the mechanical structure in a great degree. For the sliding surface in lubricating condition, the normal equivalent stiffness and normal equivalent damping mathematical analysis model of the joint surface were deduced based on the fractal theory and the mean flow generalized Reynolds equation with boundary lubrication. After simulation analysis, the equivalent normal stiffness of the solid portion, oil film portion and the comprehensive stiffness, and the comprehensive normal equivalent damping were obtained when the lubrication is on the partial film state. The results show, the contact stiffness and contact damping of the joint surface will be in an ideal state when their actual contact area ratio reached a certain value. At the same time, the dynamic and static stiffness and damping parameters of the sliding guide rail experimental device under the condition of lubrication were identified. The results show that the normal stiffness and normal damping of the guide rail will be in good state under the appropriate normal load. It is consistent well with the simulation analysis results of the mesoscopic dynamic characteristics of the sliding surface under lubrication condition.

To further improve the detection sensitivity of surface-enhanced laser-induced breakdown spectroscopy (SENLIBS), the number of repeating sample preparations in a fixed area was increased. The trace elements in an aqueous solution were quantitatively analyzed successfully. The results showed that the spectral intensities were strengthened. The limit of detection (LoD) values of Cu, Pb, Cr, and Cd were reduced from 0.072~0.36 to 0.027~0.057 μg/mL by increasing the number of repeating sample preparations from 1 to 8. This demonstrated that quantitative analytical sensitivity of SENLIBS could be improved by repeating sample preparations without increasing the cost of equipment.

This publisher’s note contains corrections to Opt. Lett. 40, 5224 (2015).OPLEDP0146-959210.1364/OL.40.005224

In this study, a simple in-situ hydrothermal method was demonstrated for fabricating a novel photocatalyst with broad spectrum response based on carbon quantum dots doped ZnIn2S4 nanoflowers(ZIS/CQDs). Compared with pure ZnIn2S4, ZIS/CQDs samples with broader sunlight spectrum responses and higher photostabilities exhibited enhanced photocatalytic performances towards photodegradation of tetracycline hydrochloride (TCH) under UV, visible, NIR light and simulated sunlight irradiation. ZIS/CQDs samples all presented higher NIR light activities while pure ZnIn2S4 showed no such ability. The up-converted photoluminescence property of CQDs in composites played an important role in enhancing NIR light response and photodegradation of TCH. Further, ZIS/CQDs sample also possessed the high visible-light photocatalytic activity to degrade rhodamine B (RhB) and methyl orange (MO). A possible mechanism of CQDs on the enhanced photocatalytic activity of ZIS/CQDs sample was also proposed.

This paper proposed the UHPC-filled high-strength steel tube (UHST) for cold-region buildings/bridges. The cold-region low-temperature environment was simulated in the laboratory using a cooling chamber with LNG. Then, low-temperature compression tests were performed on 23 stub UHSTs to study their low-temperature compression behaviour. The studied parameters included four low temperatures (T = −80, −60, −30, and 30 °C) and three width-to-thickness ratios (C/t ratio = 48.4, 33.5, 22.0). Test results showed that the P (load) − Δ (shortening) curves exhibited a four-stage manner. The UHPC crushing occurred at the ultimate load capacity and UHPC nonlinearities contributed to the nonlinear behaviour of UHSTs. Outward buckling of HSS tube and welding fracture occurred at the recession stage. The decreasing temperature from 30 °C to −80 °C improved the compression behaviour of UHSTs. As T decreases form 30 °C to −80 °C, the ultimate compressive resistance P u (or initial stiffness K0) value of UHSTs with C/t ratio of 22.0 receives the increments of 20% (24%). With the same decrease of C/t ratio, the increments of peak load capacity decreased as T decreased from 30 °C to −80 °C. This paper also developed finite element models (FEMs) and theoretical models to simulate the axial compression behaviour of UHSTs at low temperatures. Validations of simulations against 23 test results proved that both the FEM and theoretical models provided reasonable simulations on axial low-temperature compression behaviours of UHSTs.

We report that the efficiency of the spin-Hall spin–orbit torque (SOT) in perpendicularly magnetized Pt/Co/MgO films can be engineered by introducing ruthenium (Ru) impurities into the bulk of the Co layer. As the concentration of the Ru impurities increases, the effective field of the damping-like SOT is increased by a factor of 2.3, leading to SOT efficiency per unit current density enhancing from 0.069 to 0.155. However, the Ru incorporation shows less impact on the field-like SOT efficiency. First-principles calculations reveal that the Ru incorporation can significantly increase the density of states of the majority spin at the Fermi level but has less influence on the minority spin case. We suspect that such an electronic-structure modulation may reduce the scattering of the spin-Hall spin currents flowing across the Co-Ru layer, resulting in SOT efficiency enhancement. The SOT enhancement by Ru incorporation is also observed in Ta/CoFeB/MgO films, indicating that modulating the spin scattering inside ferromagnets with judiciously selected impurities is a promising strategy to construct low-power-dissipation SOT spintronic devices.

Optical fiber displacement sensor has the advantages of high sensitivity, large dynamic range, long sensing distance and high electromagnetic interference resistance, which has been widely used in many industrial and civil fields. However, multi-parameter simultaneous sensing is the common requirement in many applications. In this paper, we demonstrated a novel and simple optical fiber displacement sensor based on the principle of Stokes Raman backscattering, and the Stokes Raman signal is used to sense the bending loss of the sensing fiber. An optical fiber displacement sensing system and a recoverable displacement sensor is designed and built to measure the optical power loss, which makes it possible to detect the temperature and displacement simultaneously use one optical fiber. The displacement measurement is carried out for five times at 0.25 mm intervals in the range of 0–5 mm, and the experimental results show that there is a good linearity between measured and applied displacement. Its measurement accuracy is 0.1 mm and maximum sensitivity is 0.343 dB/mm. This sensor has the potential to be applied in foundation settlement monitoring, safety pre-warning of subway on-site, soil deformation measurement, and civil structure crack monitoring.

Stand-off laser-induced breakdown spectroscopy (ST-LIBS) has attracted increasing attention as a valuable method for the remote analysis of materials. In this work, a multi-collector (MC) system combining low cost small lenses imitating the structure and shape of an artificial optical compound eye (AOCE) is presented to enhance the spectral intensity of ST-LIBS. The volume of the MC system is one eighteenth smaller than that of a telescope system and the number of collectors can be flexibly changed according to the requirements. The mechanisms of spectral enhancement are also discussed. In order to illustrate the performance of the MC system, the spectral intensities and the limits of detection (LoDs) of Mn and Cr elements acquired by the telescope system and the MC system were compared at a distance of 2 meters. The results showed that the spectral intensity acquired from the MC system was enhanced by 2.2 times, and the LoDs of Mn and Cr were decreased to 294 μg g−1 and 49 μg g−1. These results indicate that the MC system has great potential in providing a portable, flexible and effective collection method for remote detection.

To minimize the impact of spectral interference on laser-induced breakdown spectroscopy (LIBS) quantitative analyses, an algorithm based on wavelet transform was developed for simultaneous correction of spectral interference and continuum background. The root-mean-square error of calibration (RMSEC) of the univariate regression model for the element of interest was applied to determine the wavelet function, decomposition level, and scaling factor α. When the interference-free analytical lines of the elements of interest cannot be directly obtained from the measured spectra, they can be extracted from the spectra with the developed method for quantitative analysis. This method was applied for LIBS analyses of chromium (Cr), silicon (Si), titanium (Ti), and manganese (Mn) with continuum backgrounds and spectral interference in low alloy steel samples. The root-mean-square errors of cross-validation (RMSECV) of elements Cr, Si, Ti, and Mn were 0.0295, 0.0140, 0.0183, and 0.0558 wt%, respectively. The results demonstrated that the developed algorithm contributed to accuracy improvement for LIBS quantitative analyses with the presence of spectral interference.

Optical fiber distributed vibration and temperature sensor are very important for many applications. It is challenging to design a hybrid vibration and temperature sensing system because multi-parameter simultaneous sensing is the common requirement in most applications. In this paper, we demonstrated a novel distributed vibration and temperature simultaneous sensing system using standard optical fiber, which based on Rayleigh and Raman backscattering light. We have performed several temperature and vibration tests under different circumstances. The maximum temperature measurement deviation is 0.6 °C and maximum consistency deviation of three sensing units is 0.9 °C. The continuous vibration signal has been detected by using standard audio signal as the vibration source and the detectable frequency range is 0 Hz–5 kHz. In particular, we have carried simultaneous sensing test, which the vibration and temperature signals are detected successfully by one sensing unit at the same time. This new optical fiber distributed multi-parameter simultaneous sensing system is potentially used in pipeline and power cable for temperature and vibration monitoring.

Incorporating heterojunctions and constructing structures are reliable strategies to solve the problem of inefficient intrinsic charge generation in semiconductors. In this study, a direct Z-scheme heterojunction was formed ingeniously, via the intimate coaxial contact of SnIn4S8-CdS (SISCS) core-shell nanostructure. The prepared core-shell SISCS composites exhibited more superior photocatalytic oxidation and reduction capabilities in comparison with bare CdS and SnIn4S8. Significantly, the SISCS2 sample could reduce 98.9% of Cr (VI) (20 mg/L) and degrade almost all methyl orange (MO) (15 mg/L) within 24 min. The apparent rate constants of Cr (VI) and MO photodegradation over SISCS2 were 3.52 and 7.52 times than those of bare CdS nanorods, 4.57 and 5.59 folds as those of pure SnIn4S8, respectively. The intimate coaxial contact between CdS and SnIn4S8 efficiently enhanced the charge transfer, and the redox ability of the CdS and SnIn4S8 could be maintained crediting to the Z-scheme system heterojunction. Moreover, the enlarged specific surface area and the super-hydrophilic surface could both ensure excellent photocatalytic activity of SISCS composites. Furthermore, the Z-Scheme photocatalytic mechanism and the degradation pathways of MO were also discussed in depth.

In this paper, we prepared a fluorescent sensor based on carbon quantum dots (CDs) and molecularly imprinted technology (MIT) that was successfully synthesized and applied to the detection of aspirin (Asp) residues in biological and pharmaceutical samples. The molecularly imprinted fluorescence sensor had the high sensitivity of quantum dots and the high selectivity of molecularly imprinted polymers (MIPs). Nitrogen-doped carbon quantum dots (N-CDs) with high fluorescence intensity were prepared and then was coated with silicon by the reverse microemulsion method. Finally, 3-aminopropyltriethoxysilane (APTES) was used as the functional monomer and Asp as the template molecule, molecularly imprinted layers were formed around the N-CDs. Under the best experimental conditions, the detection limit of the sensor was 0.198[Formula: see text]mg[Formula: see text]L[Formula: see text]. Between 0.9–9.0[Formula: see text]mg[Formula: see text]L[Formula: see text], this fluorescence sensor had a good linear relationship with the concentration of Asp. To test the practicability of the sensor, we used this fluorescent sensor to detect Asp in human urine and saliva. Satisfied recovery rate between 101.1–105.1% and 102.1–106.0% were obtained, respectively.

Phosphorus has been an important main reason for water eutrophication. Reducing the concentration of phosphate to prevent eutrophication is one of the crucial goals of sewage engineering and surface water management. For the first time, cellulose nanocrystalline was used as biomass template and tetramethoxysilane as mesoporous template. A highly efficient and selective self-supporting mesoporous composite membrane adsorbent was prepared by one-step method. The film material has a highly ordered chiral nematic phase structure. It adsorbed phosphate well. In batch adsorption test, through lanthanum loading, the adsorbent material can selectively adsorb phosphate, and the adsorption kinetics followed a pseudo second-order model, especially in the case of phosphate. At the same time, cellulose nanocrystalline doped with trace lanthanum have been investigated to achieve high phosphate adsorption performance. The effect of Lanthanum on flocculation of cellulose nanocrystalline was discussed, and the adsorbent material with the best adsorption performance was obtained. The adsorption isotherm Langmuir model of the adsorbent was more representative than the Friedrich model. In addition, the adsorbent was achieved a high adsorption capacity in the range of pH values between 3.0 and 7.0. Phosphate selectivity was also soaring. The mesoporous films adsorbent has the advantages of high cycle times, repeatability and easy separation from solution.

A portable laser-induced breakdown spectroscopy (LIBS) system based on a fiber laser was developed and employed to quantitatively analyze manganese (Mn), vanadium (V), and silicon (Si) elements in steels. After background removal, the coefficients of determination (R2 factors) of the calibration curves for Mn, V, and Si elements reached 0.997, 0.991 and 0.992, respectively, obvious improvements compared to those of the original spectra. The leave-one-out cross-validation (LOOCV) method was used to test the system. The root-mean-square error of cross-validation (RMSECV) for Mn (0.072–2.06 wt%), V (0.009–0.821 wt%), and Si (0.099–1.85 wt%) elements were 0.037, 0.041 and 0.079 wt%, respectively. The average relative errors (AREs) for Mn elements reached 7.6%. These results are comparable with those of the conventional LIBS which refers to utilizing the traditional flash-lamp-pumped laser as a laser source. However, compared to conventional LIBS, a fiber laser LIBS (FL-LIBS) is more compact, robust, and cost effective. The FL-LIBS, coupling a compact fiber laser and spectrometer, is a convenient approach to providing a portable solution for real-time and in situ detection in industry, especially in harsh environments.

Modulating the soft magnetic properties of amorphous magnetic thin films is important for constructing energy-efficient and high performance thin film inductors. Here, a metal (Pt) and an oxide (Al2O3) are selected as the covering layer to investigate the effect of the interfacial microstructure on the magnetic properties of CoZrTa thin films. The results show that the magnetic dead layer thickness (tDL) and coercivity (Hc) decrease and saturation magnetization (Ms) increases with the annealing temperature for the CoZrTa/Al2O3 sample. However, tDL, Hc, and Ms of the CoZrTa/Pt sample show an opposite variation tendency with the annealing temperature. Interfacial structural results indicate that different magnetisms can be ascribed to different interfacial oxygen migration and interfacial diffusion processes. The effective interfacial oxygen migration in CoZrTa/Al2O3 reconstructs oxygen atom distribution at the interface and provides an effective way to enhance the magnetic properties of CoZrTa, whereas the intensified interfacial diffusion between CoZrTa and Pt after annealing in the CoZrTa/Pt sample caused the deterioration of the magnetism. This study will be helpful in advancing the development of magnetic thin film inductor devices.

Correction for ‘Evaluation of the self-absorption reduction of minor elements in laser-induced breakdown spectroscopy assisted with laser-stimulated absorption’ by Jiaming Li et al., J. Anal. At. Spectrom., 2017, 32, 2189–2193, DOI: 10.1039/C7JA00199A.

Correction for ‘Quantitative analyses of Mn, V, and Si elements in steels using a portable laser-induced breakdown spectroscopy system based on a fiber laser’ by Qingdong Zeng et al., J. Anal. At. Spectrom., 2016, 31, 767–772, DOI: 10.1039/C5JA00453E.

Correction for ‘Fabrication of metal/semiconductor nanocomposites by selective laser nano-welding’ by Huiwu Yu et al., Nanoscale, 2017, 9, 7012–7015.

Correction for ‘Wavelet-based interference correction for laser-induced breakdown spectroscopy’ by Y. M. Guo et al., J. Anal. At. Spectrom., 2017, 32, 2401–2406, 10.1039/C7JA00204A.

Correction for ‘A portable multi-collector system based on an artificial optical compound eye for stand-off laser-induced breakdown spectroscopy’ by W. T. Li et al., J. Anal. At. Spectrom., 2017, 32, 1975–1979, DOI: 10.1039/C7JA00173H.

Correction for ‘Quantitative analysis of phosphorus in steel using laser-induced breakdown spectroscopy in air atmosphere’ by Chang Mao Li et al., J. Anal. At. Spectrom., 2014, 29, 1432–1437, DOI: 10.1039/C4JA00036F.

Correction for ‘Investigation of the self-absorption effect using spatially resolved laser-induced breakdown spectroscopy’ by Rongxing Yi et al., J. Anal. At. Spectrom., 2016, 31, 961–967, DOI: 10.1039/C5JA00500K.

To improve the quantitative analysis accuracy of an aqueous solution using surface-enhanced laser-induced breakdown spectroscopy (SENLIBS), the filter paper was used as a transmission medium by placing it onto the surface of a metallic substrate to make the microdroplet spreading more uniform in a fixed region of the substrate surface. The trace elements (Cu, Pb, Cd, and Cr) in an aqueous solution were detected successfully using this method. The results showed that the sample preparation repeatability of SENLIBS was noticeably improved with the aid of filter paper. Moreover, the limit of detection (LoD) values was similar to those without filter paper. Furthermore, the R2 values were improved from 0.6192~0.9321 to 0.9481~0.9766, the RMSECV values were decreased from 0.53~1.95 μg/mL to 0.33~1.06 μg/mL, and the average relative error (ARE) values were decreased from 8.96~22.31% to 4.28~14.37% with the aid of filter paper. This demonstrated that the use of filter paper could improve the quantitative analysis accuracy of SENLIBS by increasing the sample preparation repeatability.

In this study, chemical replacement combined with surface-enhanced laser-induced breakdown spectroscopy (CR-SENLIBS) was introduced for detecting the trace chromium (Cr) element in an aqueous solution, which could use chemical replacement to change the sample from liquid to solid. In order to illustrate the analytical-performance of the CR-SENLIBS, the direct analysis of the liquid surface by LIBS (LSLIBS) was investigated for comparison. The results show that the spectral intensity of Cr I 357.86 nm, plasma lifetime, and spectral stability were improved. Moreover, the limit of detection of Cr I 357.86 nm was 0.018 μg/mL, which was lower than 1.814 μg/mL for LSLIBS. Furthermore, the accuracy and precision were improved more than 60% and 80%, respectively; for example, the root-mean-square error of cross-validation was improved from 1.09 to 0.75 μg/mL, and the average relative standard deviation of the predicted concentration of Cr was reduced from 22.89% to 4.53% by using CR-SENLIBS. These results suggest that CR-SENLIBS has good analytical-performance, which exhibits great potential in water quality monitoring.

Chemotherapy-induced cytotoxicity in normal cells and organs triggers undesired lesions. Although targeted delivery is used extensively, more than half of the chemotherapy dose still concentrates in normal tissues, especially in the liver. Enabling normal cells or organs to defend against cytotoxicity represents an alternative method for improving chemotherapy. Herein, rationally designed nanomaterials are used as artificial organelles to remove unexpected cytotoxicity in normal cells. Nanocomposites of gold-oligonucleotides (Au-ODN) can capture intracytoplasmic doxorubicin (DOX), a standard chemotherapy drug, blocking the drug's access into the cell nucleus. Cells with implanted Au-ODN are more robust since their viability is maintained during DOX treatment. In vivo experiments confirm that the Au-ODN nanomaterials selectively concentrate in hepatocytes and eliminate DOX-induced hepatotoxicity, increasing the cell's capacity to resist the threatening chemotherapeutic milieu. The finding suggests that introducing functional materials as biological devices into living systems may be a new strategy for improving the regulation of cell fate in more complex conditions and for manufacturing super cells.

A green and simple method to prepare metal/semiconductor nanocomposites by selective laser nano-welding metal and semiconductor nanoparticles was presented, in which the sizes, phases, and morphologies of the components can be maintained. Many types of nanocomposites (such as Ag/TiO2, Ag/SnO2, Ag/ZnO2, Pt/TiO2, Pt/SnO2, and Pt/ZnO) can be prepared by this method and their corresponding performances were enhanced.

The quantitative analysis of phosphorus in iron/steel in air atmosphere is considered a challenge for laser-induced breakdown spectroscopy (LIBS) due to strong interference from the matrix. In this study, interference from the iron and copper lines on the P I 214.91 nm line using different gate delays was studied. The interference on the P I 214.91 nm line arises mainly from the ionic lines of iron and copper in the steel. By choosing the gate delays carefully, the interference can be reduced. The spectral resolution and sensitivity of the spectrometer required for the detection of the P I 214.91 nm line in steel plasma were also studied. Based on the results, a Czerny–Turner spectrometer equipped with an intensified charge coupled device camera with a minimum spectral resolution of 0.03 nm is suggested for this application. Finally, the successful quantitative analysis of phosphorus in the UV-vis spectral range was carried out both in pig iron and a low alloy steel. For the pig iron, the R2 calibration factor was 0.9992, the limit-of-detection (LoD) was 12 ppm and the background equivalent concentration (BEC) was 0.11 wt%. For the low alloy steel, the R2 calibration factor was 0.995, the LoD was 9 ppm and the BEC was 0.05 wt%. Interference from copper lines on the P I 214.91 nm line was not observed. It has been shown that a simple LIBS setup can be used for the accurate quantitative analysis of phosphorus in iron/low alloy steel in open air.

Laser-induced breakdown spectroscopy (LIBS) is a powerful tool in the soil monitoring field, but the poor spectral quality limits its application. To improve the spectral quality of major elements in soil samples, a method based on controlling the ambient pressure and time sequence was introduced. Spectral qualities that include signal-to-background ratio (SBR), spectral stability, and spectral profile were all studied in different ambient pressures and delay times. The results show that the SBRs of Na and K elements increased from 20 to about 300, when the air pressure and delay time were controlled. Meanwhile, the relative standard deviations were improved from more than 30% to less than 5% due to the release of the self-absorption effect. This work proved that the spectral qualities of LIBS can be improved a lot by controlling the ambient pressure in the field of detecting major elements in soil.

The self-absorption at reduced air pressure for quantitative analysis of Mn and Cu elements in steel using laser-induced breakdown spectroscopy was investigated. The calibration curves of Mn and Cu elements at the air pressures of 100, 80, 50, 20, and 1 kPa were studied. The results show that, the nonlinearity of calibration curves which caused by self-absorption effects at atmosphere could be significantly improved by reducing the air pressure to 1 kPa, and the coefficients of determination (R2) of linear calibration curves of Mn and Cu lines are all higher than 0.99. The further study explored that the reason for the improvement was that the induced plasma became low density and the self-absorption coefficient was close to 1 when the air pressure reduced to 1 kPa.

In this study, chemical replacement combined with surface-enhanced laser-induced breakdown spectroscopy (CR-SENLIBS) was for the first time applied to improve the detection sensitivities of trace heavy metal elements in aqueous solutions. Utilizing chemical replacement effect, heavy metal ions in aqueous solution were enriched on the magnesium alloy surface as a solid replacement layer through reacting with the high chemical activity metallic magnesium (Mg) within 1 minute. Unitary and mixed solutions with Cu, Pb, Cd, and Cr elements were prepared to construct calibration curves, respectively. The CR-SENLIBS showed a much better detection sensitivity and accuracy for both unitary and mixed solutions. The coefficients of determination R2 of the calibration curves were above 0.96, and the LoDs were of the same order of magnitude, i.e., in the range of 0.016-0.386 μg/mL for the unitary solution, and in the range of 0.025-0.420 μg/mL for the mixed solution. These results show that CR-SENLIBS is a feasible method for improving the detection sensitivity of trace element in liquid sample, which definitely provides a way for wider application of LIBS in water quality monitoring.

The matrix effect of powder samples, especially for soil samples, is significant in laser-induced breakdown spectroscopy (LIBS), which affects the prediction accuracy of the element concentration. In order to reduce this effect of the soil samples in LIBS, the standard addition method (SAM) based on background removal by wavelet transform algorithm was investigated in this work. Five different kinds of certified reference soil samples (lead (Pb) concentrations were 110, 283, 552, 675, and 1141 ppm, respectively) were used to examine the accuracy of this method. The root mean square error of prediction (RMSEP) was more than 303 ppm by using the conventional calibration method. After adoption of SAM with background removal by wavelet transform algorithm, the RMSEP was reduced to 25.7 ppm. Therefore, the accuracy of the Pb element was improved significantly. The mechanism of background removal by wavelet transform algorithm based on SAM is discussed. Further study demonstrated that this method can also improve the predicted accuracy of the Cd element.

In this study, we present three approaches to predict particle penetration coefficients through a single straight crack in building envelops. The three approaches are an analytical approach, an Eulerian approach, and a Lagrangian approach, respectively. The particle penetration coefficient through an idealized straight crack (smooth inner surfaces) and a strand board crack (rough inner surfaces) were modeled by the three presented approaches. The calculated results were compared with the literature results. The comparison shows that for the idealized smooth crack, the modeled results by the Eulerian approach match the experiments best for the entire range of particle sizes studied among the three approaches. The predicted results by the analytical approach also match the experiments reasonable well. Results modeled by the Lagrangian approach are less satisfied for fine particles (d p < 0.1 μm). Overall, all the three approaches agree well with the experiments for particle sizes ranging from 0.4–1.2 μm. Fo...

The self-absorption effect is one of the main bottlenecks for the laser-induced breakdown spectroscopy (LIBS) technique. In this Letter, LIBS assisted by laser-stimulated absorption (LSA-LIBS) is proposed to solve this problem. The process of LSA in self-absorption reduction is discussed and confirmed. The serious self-absorption phenomena of spectral lines (K, Mn, and Al) were not observed in LSA-LIBS. The full width at half-maximum (FWHM) of K, Mn, and Al was reduced by about 58%, 25%, and 52%, respectively. The results demonstrate the capability of this approach to self-absorption reduction in the LIBS technique.

Laser-induced breakdown spectroscopy (LIBS) with partial least squares regression (PLSR) has been applied to measuring the acidity of iron ore, which can be defined by the concentrations of oxides: CaO, MgO, Al₂O₃, and SiO₂. With the conventional internal standard calibration, it is difficult to establish the calibration curves of CaO, MgO, Al₂O₃, and SiO₂ in iron ore due to the serious matrix effects. PLSR is effective to address this problem due to its excellent performance in compensating the matrix effects. In this work, fifty samples were used to construct the PLSR calibration models for the above-mentioned oxides. These calibration models were validated by the 10-fold cross-validation method with the minimum root-mean-square errors (RMSE). Another ten samples were used as a test set. The acidities were calculated according to the estimated concentrations of CaO, MgO, Al₂O₃, and SiO₂ using the PLSR models. The average relative error (ARE) and RMSE of the acidity achieved 3.65% and 0.0048, respectively, for the test samples.

This research focused on anti-tumor effect of pEGFP-C1-p53 (p53) gene-loaded hydroxyapatite (HAp) nanoparticles in vitro and in vivo. Four kinds of HAp nanoparticles, spherical HAp nanoparticles (S-HAp, diameter: 50 nm), needle-like HAp nanoparticles (N-HAp, average length: 110 nm and width: 30 nm), rod-like HAp nanoparticles (R-HAp, average length: 100 nm and width: 30 nm), and short-rod-like HAp nanoparticles (SR-HAp, average length: 40 nm and width: 30 nm), were prepared initially. The HAp nanoparticles with or without being modified by PEI (named HAp and HAp-PEI, respectively) have excellent biocompatibility as shown by MTT assay and crystal violet staining tests. Then, the subsequent MTT, Hocehst staining tests, and Western blot showed that the killing effect of p53-loaded HAp-PEI (HAp-PEI-p53) was effective with fair selectivity toward Hep-3B and HuH-7 cells’ cell lines. Moreover, HAp-PEI-p53 could inhibit the tumor growth in vivo, and the mechanism of tumor growth inhibition was verified by the hematoxylin and eosin staining, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling, P53 protein immunohistochemistry, and transmission electron microscope of the tumor cell in vivo. We found that HAp-PEI-p53 has good anti-cancer effect in vitro and in vivo, especially for the S-HAp-PEI-p53. Tumor metastasis could be suppressed significantly by the S-HAp-PEI-p53 and N-HAp-PEI-p53 treatments by the in vivo imaging system. All these results lead to the conclusion that the particle sizes of HAp ranging from 100 to 200 nm are appropriate for cancer gene therapy and may be widely used in anti-cancer investigation.

To study the characteristics of spectral lines with crater development during laser-induced breakdown spectroscopy, the changes in the spectral line intensities of iron (Fe) and chromium (Cr) during the development of craters were investigated. Images of the plasmas formed during crater development were captured, and the temperatures and electron densities of the plasmas were calculated. The results showed that when a crater developed, the intensities of the ion lines decreased and the intensities of the atomic lines increased. This is because the plasmas generated in the crater have a higher initial emission intensity and experience more rapid cooling as the crater develops. These two effects lead to changes in the rates of decrease of ion and atomic line intensities over time. Therefore, the changes in intensities of ion lines caused by crater development differ from which of atomic lines.