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Experimentally Calibrated Kinetic Monte Carlo Model Reproduces Organic Solar Cell Currenta??Voltage Curve
摘要： Kinetic Monte Carlo simulations are used to describe the current-voltage characteristics of an organic bulk heterojunction solar cell. Excellent agreement between model and experiment is obtained by calibrating the injection barriers, the blend morphology and the charge transfer recombination rate with data from independent measurement techniques.
关键词： organic photovoltaics,charge recombination,Kinetic Monte Carlo simulations,morphology,charge injection
更新于2025-09-23 15:19:57
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Deviations from generalized equipartition in confined, laser-cooled atoms
摘要： We observe a signi?cant steady-state deviation from the generalized equipartition theorem, one of the pivotal results of classical statistical mechanics, in a system of con?ned, laser-cooled atoms. We parametrize this deviation, measure its dynamics, and show that its steady-state value quanti?es the departure of nonthermal states from thermal equilibrium even for anharmonic con?nement. In particular, we ?nd that deviations from equipartition grow as the system dynamics becomes more anomalous. We present numerical simulations that validate the experimental data and reveal an inhomogeneous distribution of the kinetic energy through the system, supported by an analytical examination of the phase space.
关键词： kinetic energy distribution,laser-cooled atoms,generalized equipartition theorem,anharmonic con?nement,nonthermal states
更新于2025-09-23 15:19:57
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Diastereoselective Photooxidation and Reduction of Chiral Iridium(III) Complexes
摘要： A diastereoselective photooxidation of α-amino acid (AA) complexes into imino acid complexes using a chiral iridium(III) complex as a photosensitizer and stereo-controller under visible light irradiation and oxygen was developed. It was found that the oxidative rate of Δ-[Ir(pq)2(L-AA)] (pq is 2-phenylquinoline) diastereomer is significantly higher than that of the corresponding Δ-[Ir(pq)2(D-AA)] diastereomer, providing a new protocol for kinetic resolution of AAs via a nonenzymatic pathway. Moreover, the thermodynamic controlled strategy offered a complemental method for the diastereoselective hydrogenation of imine bonds using NaBH4 as a reductant under the chiral Ir(III) complex as a stereo-controller. The combination of diastereoselective photooxidation and reduction processes results in a new protocol for deracemization of α-amino acids under mild conditions. Mechanism study strongly indicates that singlet oxygen is a key participant in the reaction and the α-C?H bond cleavage of AAs is the rate-determining step.
关键词： kinetic resolution,diastereoselective photooxidation,chiral iridium(III) complex,deracemization,α-amino acids
更新于2025-09-23 15:19:57
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Improved repeatability of dynamic contrast-enhanced MRI using the complex MRI signal to derive arterial input functions: a test-retest study in prostate cancer patients
摘要： Purpose: The arterial input function (AIF) is a major source of uncertainty in tracer kinetic (TK) analysis of dynamic contrast‐enhanced (DCE)‐MRI data. The aim of this study was to investigate the repeatability of AIFs extracted from the complex signal and of the resulting TK parameters in prostate cancer patients. Methods: Twenty‐two patients with biopsy‐proven prostate cancer underwent a 3T MRI exam twice. DCE‐MRI data were acquired with a 3D spoiled gradient echo sequence. AIFs were extracted from the magnitude of the signal (AIFMAGN), phase (AIFPHASE), and complex signal (AIFCOMPLEX). The Tofts model was applied to extract Ktrans, kep and ve. Repeatability of AIF curve characteristics and TK parameters was assessed with the within‐subject coefficient of variation (wCV). Results: The wCV for peak height and full width at half maximum for AIFCOMPLEX (7% and 8%) indicated an improved repeatability compared to AIFMAGN (12% and 12%) and AIFPHASE (12% and 7%). This translated in lower wCV values for Ktrans (11%) with AIFCOMPLEX in comparison to AIFMAGN (24%) and AIFPHASE (15%). For kep, the wCV was 16% with AIFMAGN, 13% with AIFPHASE, and 13% with AIFCOMPLEX. Conclusion: Repeatability of AIFPHASE and AIFCOMPLEX is higher than for AIFMAGN, resulting in a better repeatability of TK parameters. Thus, use of either AIFPHASE or AIFCOMPLEX improves the robustness of quantitative analysis of DCE‐MRI in prostate cancer.
关键词： arterial input function,dynamic contrast‐enhanced MRI,repeatability,prostate cancer,tracer kinetic analysis,complex signal
更新于2025-09-19 17:15:36
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Degradation of carbamazepine by vacuum-UV oxidation process: Kinetics modeling and energy efficiency
摘要： Vaccum-ultraviolet (VUV) is effective for elimination of organic contaminants in aqueous environment and degradation of carbamazepine (CBZ) by VUV irradiation was systematically investigated in this study. A dynamic kinetic model was developed to simulate the destruction of CBZ that is mainly initiated by hydroxyl radicals (HO?). The second-order rate constant of the reaction between CBZ and HO? was determined to be 1.4×109 M-1 s-1. Effect of initial CBZ concentration, VUV irradiation intensity and natural organic matter (NOM) were further investigated in several batch experiments. The predicted CBZ removal rates increased with the increasing VUV intensity, while decreased with the increasing initial CBZ and NOM concentrations. Based on the electrical energy per order (EE/O) calculation, the optimal VUV intensity was determined to be 7.5×10-8 Einstein s-1. Meanwhile, several intermediates/products were identified and their time-dependent evolution profiles were determined, and finally a plausible degradation pathway of CBZ was proposed. Ecotoxicity assessment indicated that the potential toxicity of CBZ and its oxidation products should be paid more attention in the VUV process.
关键词： Kinetic model,Degradation pathway,Energy efficiency,Hydroxyl radical
更新于2025-09-19 17:15:36
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Modeling the Optimal Conditions for Improved Efficacy and Crosslink Depth of Photo-Initiated Polymerization
摘要： Optimal conditions for maximum ef?cacy of photoinitiated polymerization are theoretically presented. Analytic formulas are shown for the crosslink time, crosslink depth, and ef?cacy function. The roles of photoinitiator (PI) concentration, diffusion depth, and light intensity on the polymerization spatial and temporal pro?les are presented for both uniform and non-uniform cases. For the type I mechanism, higher intensity may accelerate the polymer action process, but it suffers a lower steady-state ef?cacy. This may be overcome by a controlled re-supply of PI concentration during the light exposure. In challenging the conventional Beer–Lambert law (BLL), a generalized, time-dependent BLL (a Lin-law) is derived. This study, for the ?rst time, presents analytic formulas for curing depth and crosslink time without the assumption of thin-?lm or spatial average. Various optimal conditions are developed for maximum ef?cacy based on a numerically-?t A-factor. Experimental data are analyzed for the role of PI concentration and light intensity on the gelation (crosslink) time and ef?cacy.
关键词： optimal ef?cacy,crosslinking,polymerization modeling,photoinitiator,kinetic
更新于2025-09-19 17:15:36
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Evaluation of the hydraulic and hydrodynamic parameters influencing photo-catalytic degradation of bio-persistent pollutants in a pilot plant
摘要： A kinetic study on the photo-catalytic degradation of bio-persistent micro-pollutants, as methyl red and methylene blue dyes, was carried out on an innovative unit by changing the hydraulic and hydrodynamic parameters of the system. The catalyst (TiO2, anatase) was embedded into a cement matrix and deposited at the bottom of a channel to activate the UVB photo-degradation reactions. The influence of the catalyst dosage, substrate concentration c0, and pH was evaluated on the degradation rates. The optimum catalytic dose was obtained at 0.79 g/cm3 while the best results were observed at 0.7 mg/L influent dye concentration. The pH of the solution influenced the sorption phenomena because the charge of the substrates functional groups as well as the charge of the catalyst surface were affected by this parameter. Different unit geometries, hydraulic loads (hw) and gradients (i) affected speed and flow-rate (Q) of the liquid phase and, as a consequence, the irradiated retention times (Irt) of the substrates to the UV/TiO2 system. Kinetics resulted faster at increasing flow-rates of the liquid flowing through the channel, constant the hydraulic load, whereas the increase in the hydraulic load did not improve the performances. Finally, degradation rates slightly decreased after the increase in the hydraulic gradient of the channel.
关键词： Organic micro-pollutant removal,Hydraulic and hydrodynamic parameters,Kinetic study,Photo-catalysis,Textile wastewater,Pilot plant
更新于2025-09-19 17:15:36
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Braiding kinetics and spectroscopy in photo-catalysis: the spectro-kinetic approach
摘要： The combination of kinetic and spectroscopic tools has become a key scientific methodology for the understanding of catalytic behavior but its application in photocatalysis has inherent difficulties due to the nature of the energy source of the reaction. This review article provides an overview of its use by, first, presenting mechanistically derived kinetic formulations and spectroscopic data handling methods including intrinsic expressions for light and, second, highlighting representative examples of application. To do it we consider universal catalytic systems, particularly (although not exclusively) titania-based materials, and the most frequent hole and/or electron triggered reaction schemes. This review also provides a general framework to pave the way for the future progress of the spectro-kinetic approach in the photocatalysis area.
关键词： spectroscopy,titania-based materials,kinetics,hole and electron triggered reactions,photocatalysis,spectro-kinetic approach
更新于2025-09-19 17:15:36
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Kinetic modeling of spatio-temporal evolution of the gain in copper vapor active media
摘要： This paper addresses the theoretical study of the spatio-temporal gain profile of the copper vapor active media. The description of a kinetic model of a copper vapor amplifier which allows us to study spatio-temporal evolution of the amplifying characteristics is described. Using the kinetic model time and radial evolution of the medium optical gain and factors which governs the radial gain profile inhomogeneity of the brightness amplifier are shown.
关键词： brightness amplifier,laser radiation,laser monitor,beam profile,kinetic model,active optical system
更新于2025-09-19 17:15:36
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Simulating dynamically assisted production of Dirac pairs in gapped graphene monolayers
摘要： In a vicinity of the Fermi surface, graphene layers with bandgaps allow for closely simulating the vacuum of quantum electrodynamics and, thus, its yet unverified strong-field phenomenology with accessible field strengths. This striking feature is exploited to investigate a plausible materialization of dynamically assisted pair production through the analog production of light but massive pairs of Dirac quasiparticles. The process is considered in a field configuration combining a weak high-frequency electric mode and a strong low-frequency electric field oscillating in time. Its theoretical study is carried out from a quantum kinetic approach, similar to the one governing the spontaneous production of pairs in QED. We show that the presence of the weak assisting mode can strongly increase the number of produced massive Dirac pairs as compared with a setup driven by the strong field only. The efficiency of the process is contrasted, moreover, with the case of gapless graphene to highlight the role played by the quasiparticle mass.
关键词： gapped graphene,dynamically assisted pair production,quantum kinetic approach,Schwinger mechanism,Dirac pairs
更新于2025-09-19 17:15:36