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Quantitative Analysis of Organic Liquid Three-Component Systems: Near-Infrared Transmission versus Raman Spectroscopy, Partial Least Squares versus Classical Least Squares Regression Evaluation and Volume versus Weight Percent Concentration Units
摘要： The band shapes and band positions of near-infrared (NIR) and Raman spectra change depending on the concentrations of specific chemical functionalities in a multicomponent system. To elucidate these effects in more detail and clarify their impact on the analytical measurement techniques and evaluation procedures, NIR transmission spectra and Raman spectra of two organic liquid three-component systems with variable compositions were analyzed by two different multivariate calibration procedures, partial least squares (PLS) and classical least-squares (CLS) regression. Furthermore, the effect of applying different concentration units (volume percent (%V) and weight percent (%W) on the performance of the two calibration procedures have been tested. While the mixtures of benzene/cyclohexane/ethylbenzene (system 1) can be regarded as a blended system with comparatively low molecular interactions, hydrogen bonding plays a dominant role in the blends of ethyl acetate/1-heptanol/1,4-dioxane (system 2). Whereas system 1 yielded equally good calibrations by PLS and CLS regression, for system 2 acceptable results were only obtained by PLS regression. Additionally, for both sample systems, Raman spectra generally led to lower calibration performance than NIR spectra. Finally, volume and weight percent concentration units yielded comparable results for both chemometric evaluation procedures.
关键词： Raman spectroscopy,molecular interactions,organic liquid three-component mixtures,volume/weight percent concentration units,classical least squares (CLS) regression,near-infrared (NIR) spectroscopy,partial least squares (PLS) regression
更新于2025-09-19 17:13:59
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Recent Progress in Organic Phototransistors: from Semiconductor Materials, Device Structures to Optoelectronic Applications
摘要： Chitooligosaccharides (COSs) have continuously attracted considerable attention as numerous biological activities. The highly ef?cient preparation of COSs, however, is still a challenge. In this paper, a clean two-stage method is developed to hydrolyze chitosan at high concentration into COSs, comprising of pretreatment with hydrogen peroxide (H2O2) and hydrolysis with food-grade cellulase. The pretreatment reduced the viscosity of chitosan solution quickly, making more chitosan dissolving. Chitosan solution at high concentration (9%, w/v) was successfully prepared by fed-batch chitosan during the oxidative pretreatment. Within 6 h, the chitosan was enzymatically hydrolyzed to oligosaccharides with degree of polymerization (DP) of 2e9 and a small amount of monosaccharide, which was analyzed by thin layer chromatography (TLC) and MALDI-TOF MS. In addition, the results from FT-IR and NMR spectra demonstrated the chemical structure of degraded chitosan was not signi?cantly altered. In summary, the two-stage method shows great potential in large-scale production of COSs. Besides, it is expected to couple with membrane bioreactor and immobilized enzyme technology to realize production of COSs with controlled molecular weight.
关键词： Cellulase,Fed-batch,High concentration,Chitooligosaccharides,Oxidation pretreatment
更新于2025-09-19 17:13:59
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Optical Performance Analysis of Single Flow Through and Concentric Tube Receiver Coupled with a Modified CPC Collector Under Different Configurations
摘要： Compound parabolic concentrating (CPC) collectors have great potential to provide sustainable solar thermal energy for many applications operating in the medium temperature range. This paper presents the design, development and performance evaluation of a modified CPC collector integrated with an evacuated tube receiver. The optical performance of the designed CPC paired with concentric tube receiver is compared with that of a CPC coupled with single flow through evacuated tube receiver for stationary installation in the East-West and North-South directions. Ray tracing simulations of different configurations demonstrate that CPC coupled with single flow through receivers suffer high gap losses, especially at smaller incidence angles which are considerably alleviated by a concentric tube receiver arrangement. East-West installation of CPC paired with concentric tube receiver exhibited superior optical performance than all other configurations. The yearly average optical efficiency of CPC with concentric tube receiver was 5% higher than that of a single flow through receiver within the acceptance angle. A 60% truncated CPC coupled with concentric tube receiver emerged as the most effective design, which was fabricated for experimental testing. The tests conducted under actual outdoor tropical environmental conditions demonstrated that the experimental optical efficiency reached to about 69% in the case of N-S installation and 66.5% in an E-W arrangement. The experimental results closely match the simulation outcomes, which indicate the proposed performance prediction technique as instrumental for selecting the most effective configuration of CPC collectors for medium temperature heat supply.
关键词： concentric tube receiver,single flow through tube,compound parabolic concentrator,evacuated tube receiver,optical performance,concentration ratio
更新于2025-09-19 17:13:59
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Precise near-wall pH measurement in pressure-driven and electrically-driven flows using nanoscale laser-induced fluorescence imaging
摘要： The present study developed a near-wall pH measurement technique based on nanoscale laser-induced fluorescence to evaluate the spatio-temporal distributions of pH in the vicinity of a glass-solution interface. Fluorescein sodium salt, a pH-sensitive dye, was dissolved in working fluids and excited by an evanescent wave generated by total internal reflection of a laser beam. Near-wall pH distributions were determined based on a ratiometric calibration using a high-pH buffer solution (pH ? 10) as a reference. The proposed technique was applied to both pressure-driven and electroosmotic flows to investigate the effects of interfacial potential and external electric field on proton concentration. The near-wall pH in pressure-driven flow was lower than the bulk pH by ~0.2 due to the local excess of protons attracted towards the negatively charged glass wall. This pH shift was especially noticeable in solutions with low ionic strength, which indicates that the near-wall pH is closely related to the thickness of the electric double layer. The pH shift in electroosmotic flow was smaller than that in pressure-driven flow by ~0.02 and decreased with electric field strength. In addition, a time-series measurement clearly visualized the temporal change in non-uniform pH distributions in electroosmotic flow at a spatial resolution of 5.2 × 5.2 μm. The measurement uncertainty was estimated to be 0.16 pH unit at 95% confidence level. These results demonstrated the feasibility of the present technique to evaluate spatio-temporal proton concentrations within the space 10–100 nm away from a solid–liquid interface. The proposed technique will therefore contribute to quantitative investigations into electrostatic interactions and ion transport in developing nanoscale electrochemical transport techniques and devices in, for example, biochemical analysis and water purification.
关键词： liquid–solid interface,laser-induced fluorescence,proton concentration,electric double layer,evanescent wave,electroosmotic flow,pH measurement
更新于2025-09-19 17:13:59
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STUDY OF PROPERTIES OF LASER-INDUCED PLASMA CHANNELS FODMED BY FEMTOSECOND LASER RADIATION
摘要： Laser-induced plasma channels (LIPC) formed during the interaction of ultrashort laser pulses with argon are studied. LIPC characteristics are studied at various pressures.
关键词： laser-induced plasma channel,electron concentration,electron temperature,optical breakdown
更新于2025-09-19 17:13:59
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Chemical Bonding States and Dopant Redistribution of Heavily Phosphorus-doped Epitaxial Silicon Films: Effects of Millisecond Laser Annealing and Doping Concentration
摘要： We investigated the effect of millisecond (ms) laser annealing and doping concentration on the chemical bonding states and dopant behaviors of P-doped epitaxial Si (Si:P) layers grown on Si (100) substrates using high-resolution X-ray photoelectron spectroscopy (HR-XPS), secondary-ion mass spectroscopy (SIMS) and Auger electron spectroscopy (AES) measurements. Our XPS results showed that the intensities of P 2p peaks for Si:P films were increased with P concentration and subsequent laser annealing. From the SIMS and AES measurement results, we found that P atoms were slightly accumulated at the near-surface region of the Si:P film by the laser annealing, while macroscopic P concentration being maintained in the whole Si:P films without significant diffusion of P atoms toward the Si (100) substrate. In addition, we performed ex-situ HF cleaning on the as-grown and laser-annealed Si:P films in order to precisely measure the change in chemical states and dopant distribution at the near-surface region. The intensities of the P 2p peak in the as-grown Si:P films were increased after the HF cleaning due to the removal of native oxide layers from the Si:P films. In contrast, the decrease in P 2p peak intensities was observed in the laser-annealed Si:P films after the HF cleaning, indicating the dopant loss from the near-surface region with native oxide removal.
关键词： Millisecond laser annealing,Dopant redistribution,Chemical bonding states,Phosphorus-doped epitaxial silicon films,Doping concentration
更新于2025-09-19 17:13:59
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Near-Surface Plasma Formed by Dual-Pulse Laser Action at Two Wavelengths on Titanium in Air
摘要： Spectra and structures of near-surface plasma torches were studied experimentally by measuring the speci? c mass loss and plume luminosity caused by dual-pulse laser radiation at wavelengths 1064 and 532 nm on titanium in air as functions of the time between laser pulses and their sequence. Dependences of the laser-plasma temperature and concentration of charged particles on the paired laser pulse parameters were established at laser radiation power densities q1064 ≤ 3.1·109 and q532 ≤ 2.7·109 W/cm2 for λ = 1064 and 532 nm. The optimal conditions for recording erosion plasma spectra had the initial effect from second-harmonic radiation with a time interval between pulses of 4–5 μs; for speci? c mass loss, 3–6 μs. The results were important for enhancing the ef? ciency of laser emission spectral analysis and laser-plasma processing of materials.
关键词： speci? c mass loss,laser plasma,plasma-torch structure,plasma temperature,electron concentration,dual-pulse laser action
更新于2025-09-16 10:30:52
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Copper doping of Sb2S3: fabrication, properties, and photovoltaic application
摘要： Sb2S3 solar cells are lagging behind conventional thin-film solar cells such as silicon solar cells and cadmium telluride solar cells in the power conversion efficiency (PCE). One of the most prominent problems is that the carrier concentration of Sb2S3 is relatively low. In order to increase the carrier concentration, elemental Cu was doped into Sb2S3 film by radio-frequency (RF) magnetron sputtering. We proved that Cu was doped into Sb2S3 films and mainly anchored with sulfur in the form of copper chalcogenide species at the surface and grain boundaries of Sb2S3. The doping of Cu essentially affects the physical and electrical properties of RF-sputtered Sb2S3 films such as the optical band gap, crystallinity, chemical composition, morphology, and carrier concentration. Specially, the electronic carrier concentration is remarkably increased from 6.28 × 109 to 6.06 × 1010 cm?3 and the Fermi level is also significantly uplifted after prudent doping with Cu. Planar solar cells based on RF-sputtered Cu-doped Sb2S3 absorber deliver an increased PCE of 1.13% and show good stability. This research proves that doping of Cu is an alternative and effective way to improve the electronic property of Sb2S3 films and enhance the performance of Sb2S3 solar cells.
关键词： RF magnetron sputtering,Cu-doping,photovoltaic application,carrier concentration,Sb2S3 solar cells
更新于2025-09-16 10:30:52
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[IEEE 2019 1st International Conference on Advances in Science, Engineering and Robotics Technology (ICASERT) - Dhaka, Bangladesh (2019.5.3-2019.5.5)] 2019 1st International Conference on Advances in Science, Engineering and Robotics Technology (ICASERT) - Effect of Solar Concentration on Performance of Perovskite Solar Cell: A detailed balance study
摘要： As a perovskite material, methylammonium lead iodide has become more popular for its flexibility, low-cost, lightweight, thin film and high power conversion capability in photovoltaic research community. In this work, we have explored the effect of solar concentration on PV performance for methylammonium lead iodide (CH3NH3PbI3) perovskite solar cell computationally. To calculate the band structure, bandgap and density of states (DOS) of CH3NH3PbI3, density functional theory (DFT) is used here. The detailed balance method is employed to figure out the effect of concentration on performance of perovskite solar cell. We have calculated performance parameters of CH3NH3PbI3 solar cell for two solar spectra AM 1.5 G and AM 1.5 D. All calculations have been performed at different solar concentrations ranging from no concentration to full concentration for both types solar spectra. It is found that the solar cell efficiency at 1.5 G spectrum is higher than 1.5 D solar spectrum at any solar concentration. These results may impact future research on perovskite solar cell.
关键词： Perovskite solar cell (PSC),solar concentration,PCE,density functional theory (DFT),detailed balance limit
更新于2025-09-16 10:30:52
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Implementation of a modified circuit reconfiguration strategy in high concentration photovoltaic modules under partial shading conditions
摘要： A modified circuit reconfiguration (MCR) technique for high concentration photovoltaic (HCPV) modules under partial shading conditions (PSCs) is proposed. Although HCPV modules have high conversion efficiency, they are sensitive to changing environments, especially PSCs. In response, the MCR strategy exploits the reconfigurable wiring of HCPV modules to implement the dynamic circuit reconfiguration (DCR) technique. In doing so, the hardware switches and complex control algorithms of the conventional DCR are simplified to reduce cost. Moreover, an irradiation estimation method is proposed for string current equalization using existing switches and connections. Two circuit-model prototypes, one square and one rectangular, were simulated to evaluate the proposed MCR strategy. Evaluation results demonstrate that the average output-power and conversion-efficiency improvements of the square and rectangular modules were around 31.07% and 5.00%, and 32.79% and 5.23%, respectively, when compared with the original Series connection topology. In addition, after reconfiguration by MCR, the module’s GMPP power was improved and the number of LMPPs reduced, which simplified the P-V curves. Furthermore, reliability tests demonstrated that with a small reconfiguration processing time ratio (0.06–0.28%), the daily energy harvested from the rectangular module was improved around 15%. The proposed MCR strategy has the advantages of reducing the hardware/software costs and lowering circuit losses. Additionally, the MCR method can increase the output power and efficiency of an HCPV module with high dispersion ability. The proposed method and prototypes can also be extended to larger scale arrays or implemented with other PV systems.
关键词： High concentration photovoltaic systems (HCPV),Maximum power point tracking (MPPT),Dynamic circuit reconfiguration,Partial shading conditions (PSCs)
更新于2025-09-16 10:30:52