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Effects of different molecular chain lengths and side groups on structure and property of UV-curable waterborne cathodic electrophoretic deposition coatings
摘要： A series of UV-curable waterborne cathodic electrophoretic deposition (CED) coatings with various structures were successfully developed by introducing modified acrylic monomer with different molecular chain lengths and side groups. The length of linear chain of the modified monomer had little effect on phase separation of acrylic polymer and easily formed homogeneous structure. Owing to the longer molecular chains, the pencil hardness decreased from 2H to H and the glass transition temperature reduced to 77.7 °C. The hard side groups of the modified monomer in CED coatings exhibited opposite characteristics resulting from the steric hindrance of the rigid groups and the crosslinking network, which were more likely to exhibit partial phase separation. Therefore, the stronger rigidity of the molecular structure improved the particle size to 122.42 nm, the smoothness of the CED cured film and surface contact angle decreased. And the morphology of the films became rough and surface contact angle decreased. Besides, the adhesive force and flexibility of the films could be excellent. The surface rust of the modified CED film is not remarkable under salt spray test. The photopolymerization rate (Rp) and the double bond conversion were evaluated. It was found that the Rp and the conversion obviously decreased with increasing rigid groups in acrylate molecular chains. However, the maximum decomposition temperature of it was higher than the other samples. The residue char yield (Yc) was 5.24 wt%. The stronger rigidity of the molecular structure had better thermal stability and mechanical properties.
关键词： Cathodic electrophoretic deposition coatings,Thermal stability,Photopolymerization rate,Molecular structure
更新于2025-09-23 15:22:29
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High Resolution Laser Spectroscopic Survey of the H <sup>3</sup> ?￡ <sub/>u</sub><sup>-</sup> - X <sup>3</sup> ?￡ <sub/>g</sub><sup>-</sup> Electronic Transition of Si <sub/>2</sub>
摘要： Rotationally resolved spectra of the H3Σ?u - X3Σ?g electronic transition bands of Si2 have been experimentally studied using laser induced fluorescence in the 380 - 520 nm range. Si2 molecules are produced in a supersonically expanding planar plasma by discharging a silane/argon gas mixture. In total 44 bands belonging to the H3Σ?u - X3Σ?g electronic transition system of the most abundant isotopologue 28Si2 are experimentally recorded. With a spectral resolution ～ 0.04 cm?1, the triplet spin-splitting structures in individual rotational transition lines are fully resolved. Detailed analyses on the high resolution spectra have yielded an accurate determination of spectroscopic constants for both X3Σ?g and H3Σ?u states. The spin-spin interaction constants for the two triplet states are found to be comparable (λ ～ 1.5 cm?1), which may originate from the 3p atomic orbital interaction in the triplet Si2 molecule. The measured isotopologue spectra of 29Si28Si and 30Si28Si indicate that the H3Σ?u - X3Σ?g transition system of 29Si28Si and 30Si28Si can be reasonably reproduced by the isotope mass-scaling rule. Spectroscopic parameters including the Franck-Condon factors, the Einstein coefficients, and the oscillator strengths, are also determined from the experimental results and the RKR calculations. The agreement between the experimentally measured and calculated dispersed fluorescence spectra indicates that the RKR calculations with the molecular constants determined in this work can accurately reproduce the diatomic potentials of both states. These molecular data providing a benchmark in high-level theoretical studies on Si2 and likely other small silicon clusters.
关键词： Molecular Structure,Quantum Chemistry,Spectroscopy
更新于2025-09-23 15:21:01
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Tuning Hydrogenated Si, Ge, and SiGe Nanocluster Properties Using Theoretical Calculations and a Machine Learning Approach
摘要： There are limited studies available that predict the properties of hydrogenated silicon-germanium (SiGe) clusters. For this purpose, we conducted a computational study of 46 hydrogenated SiGe clusters (SixGeyHz, 1<X+Y≤6) to predict the structural, thermochemical, and electronic properties. The optimized geometries of the SixGeyHz clusters were investigated using quantum chemical calculations and statistical thermodynamics. The clusters contained 6 to 9 fused Si-Si, Ge-Ge, or Si-Ge bonds, i.e., bonds participating in more than one 3- to 4-membered rings, and di?erent degrees of hydrogenation, i.e., the ratio of hydrogen to Si/Ge atoms varied depending on cluster size and degree of multifunctionality. Our studies have established trends in standard enthalpy of formation, standard entropy, and constant pressure heat capacity as a function of cluster composition and structure. A novel bond additivity correction model for SiGe chemistry was regressed from experimental data on 7 acyclic Si/Ge/SiGe species to improve the accuracy of the standard enthalpy of formation predictions. Electronic properties were investigated by analysis of the HOMO–LUMO energy gap to study the effect of elemental composition on the electronic stability of SixGeyHz clusters. These properties will be discussed in the context of tailored nanomaterials design and generalized using a machine learning approach.
关键词： Theoretical Calculations,SiGe Nanocluster,Ge,Machine Learning,Hydrogenated Si,Quantum Chemistry,Spectroscopy,Molecular Structure
更新于2025-09-23 15:21:01
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[IEEE 2018 57th Annual Conference of the Society of Instrument and Control Engineers of Japan (SICE) - Nara (2018.9.11-2018.9.14)] 2018 57th Annual Conference of the Society of Instrument and Control Engineers of Japan (SICE) - Evaluation of Molecular Structure in Each Processing Step of Cashmere Fibers Based on IR Spectroscopy
摘要： In this paper, we propose a molecular structure in each processing step of cashmere fibers that by using an IR spectroscopy. When manufacturing cashmere fiber products, hand touch quality and strength often decrease. In order to clarify the cause, cashmere fibers of each process were obtained from Mongolia. Absorption spectra of cashmere fiber can be measured by ATR method in IR spectroscopy. In the washing process, no change in molecular structure was shown and only wool grease was removed. The measured spectra were waveform separated and the molecular structure of the cashmere fiber was analyzed. In the cashmere fibers of each (cid:48)(cid:49)(cid:47)(cid:37)(cid:39)(cid:50)(cid:50)(cid:1)(cid:50)(cid:51)(cid:39)(cid:48)(cid:3)(cid:1)(cid:51)(cid:42)(cid:39)(cid:49)(cid:39)(cid:1)(cid:54)(cid:35)(cid:50)(cid:1)(cid:46)(cid:47)(cid:1)(cid:37)(cid:42)(cid:35)(cid:46)(cid:41)(cid:39)(cid:1)(cid:43)(cid:46)(cid:1)(cid:62)(cid:1)(cid:42)(cid:39)(cid:44)(cid:43)(cid:55)(cid:1)(cid:35)(cid:46)(cid:38)(cid:1)(cid:63)(cid:1) sheet of the secondary structure of the protein. The cashmere fibers in the bleaching and decoloring process steps showed an increase in cysteic acid by the oxidation-reduction reaction. Therefore, the cause of the decline in the quality of cashmere fiber products was chemical treatment in bleaching and decoloring process. This result is applied as a quality evaluation method in the manufacturing process of cashmere textile products.
关键词： Absorption spectrum,IR spectroscopy,Molecular structure,Cashmere fiber,Waveform separation
更新于2025-09-23 15:21:01
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A 3D nonfullerene electron acceptor with a 9,9a?2-bicarbazole backbone for high-efficiency organic solar cells
摘要： One-dimensional ladder-type nonfullerene electron acceptors (NFAs) with large fused ring cores have been widely used in highly efficient organic solar cells (OSCs). Recent studies have demonstrated that small molecule acceptors with three-dimensional (3D) structures may exhibit low energy loss, and hence can lead to improved OSC performance. In this study, a new 3D NFA (99CZ-8F) with a 9,9'-bicarbazole backbone was designed, synthesized, and characterized, where two linear A-D-A architectures were linked by a single N-N bond. 99CZ-8F showed strong absorption in the range of 500-800 nm in the solid state, which is complementary to the absorption of the donor material PM6. After regulating the morphology of the active layer via binary solvent mixture, the optimized device exhibited a maximum power conversion efficiency (PCE) of 6.6 – 0.1 %, which is among the best reported values for 3D nonfullerene electron acceptor based OSCs.
关键词： Organic solar cells,end-capped groups,3D molecular structure,bicarbazole,nonfullerene electron acceptor
更新于2025-09-23 15:19:57
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Processing induced changes in physicochemical structure properties and nutrient metabolism and their association in cool-season faba (CSF: <i>Vicia L.</i> ), revealed by vibrational FTIR spectroscopy with chemometrics and nutrition modeling techniques
摘要： This review aims to update recent progress in processing induced molecular structure changes in the association of physicochemical structure properties with nutritional metabolism in cool-season faba bean (Vicia L.), which was revealed using advanced vibrational molecular spectroscopy in combination with chemometrics and advanced nutrient modeling techniques. The review focused on strategies to improve the utilization of the cool-season faba bean through heat-related technological treatments and the relationship of the processing induced molecular structural changes to nutrient delivery and metabolism in ruminant systems. The updated methods with truly absorption nutrient modeling techniques and advanced vibrational molecular spectroscopy techniques sourced by globar and synchrotron radiation (e.g. NIR, near Infrared, FTIR, Fourier transform infrared, DRIFT, diffuse reflectance infrared Fourier transform, ATR-FTIR, attenuated total reflectance-FTIR, FTIRM, FTIR micro-spectroscopy, SR-FTIRM, synchrotron radiation- FTIRM) to study cool-season faba bean were reviewed. This article provides an insight and a new approach on how to combine advanced nutrient modeling techniques with cutting-edge vibrational molecular spectroscopic techniques to study the processing induced molecular structure change in relation to molecular nutrition of cool-season Vicia faba as well as the interaction between molecular structure and molecular nutrition.
关键词： molecular structure,modeling,vibrational spectroscopy,Technological processing,cool-season Vicia faba,nutrient metabolism
更新于2025-09-23 15:19:57
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Energy Landscapes in Photochemical Dissociation of Small Peroxides
摘要： Organic peroxides are known to have important roles in many chemical and biochemical processes such as intermediates in the oxidation of various hydrocarbons, as initiators of free-radical polymerization and cross-linking agents, etc. Consequently, the study of the organic peroxides and their radicals are of fundamental interest and importance. Although several reaction pathways after dissociation of organic peroxides have been successfully identified using time-resolved optical absorption spectroscopy, interpretation of the data can be complicated due to spectral overlap of parent molecules, intermediates, and products. Therefore, a reliable theoretical framework is necessary in case of complex or less studied systems. In this study, we investigated the plausible thermal dissociation pathways of diethyl peroxide, di-tert butyl peroxide and dicumyl peroxide by density functional theory with M06-2X hybrid functional and compare its results to coupled cluster single double and perturbative triple, CCSD(T), level energies. Our results indicate that methyl radical elimination is the main dissociation mechanism for all the studied peroxides after O-O bond cleavage which has been also observed in experiments. The resulted relative energies of M06-2X functional were found to have reasonable accuracy in comparison with CCSD(T) method. We also show that time-dependent density functional theory (TD-DFT) with M06-2X functional provides a suitable guide for interpretation of time-resolved optical absorption spectra of peroxides. The experimental transient absorption spectra of dicumyl peroxide are interpreted using the theoretically predicted pathways and transient radical species. Both results agree within experimental resolution and accuracy. We propose that the traditionally assigned visible absorption is not due to the cumuloxyl radical and the photodissociation of dicumyl peroxide involves other pathways with extremely short lived radicals.
关键词： Molecular Structure,Spectroscopy,Quantum Chemistry
更新于2025-09-19 17:15:36
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IR Cavity Ringdown Spectroscopy and Density Functional Theory for Jet-Cooled Pyrrolea??Cyclopentanone Binary Clusters: Effect of Pseudorotation on Na??H?·?·?·Oa??C Hydrogen Bonds
摘要： The geometry and energetics of the N-H…O=C hydrogen bond (H-bond) are important to understand the stability and flexibility of biomolecules, such as protein and DNA. Jet-cooled pyrrole-cyclopentanone (Py-Cp) binary clusters are appropriate models to investigate the N-H…O=C H-bond from a microscopic point of view. In this study, NH stretching vibrations of the Py-Cp binary clusters were observed by IR cavity ringdown spectroscopy. Furthermore, density functional theory calculations revealed geometric structures, harmonic vibrations, intermolecular energies, and donor-acceptor interactions for various sizes of binary clusters. The IR spectra of the Py-Cp binary clusters were measured under various conditions of the vapor pressures of Py and Cp in He buffer gas for a supersonic expansion. The dependence of the IR band intensities on the vapor pressure provides vibrational assignments of the NH stretching vibrations, which were reproduced by calculated frequencies of Py1-Cp1, Py1-Cp2, and Py2-Cp1. An admixture of Ar in He buffer gas for a supersonic expansion was also applied to produce Py1-Cp2 in order to differentiate several NH stretches of isomeric structures due to the pseudorotation of Cp molecules. Py1-Cp1 is formed by the N-H…O=C H-bond. Py1-Cp2 has a cyclic structure that is formed by the N-H…O=C H-bond and stacking interactions among Py and two Cp molecules. Py2-Cp1 also has a cyclic structure that is formed by not only the N-H…O=C H-bond, but also a N-H…π H-bond between two Py molecules and a stacking interaction between Py and Cp. A comparison of the H-bond geometries between Py2-Cp1 and the corresponding pyrrole-acetone binary cluster reveals that the stacking interaction between Py and Cp strengthens the N-H…O=C and N-H…π H-bonds through a cooperative effect.
关键词： Density Functional Theory,Cyclopentanone,Spectroscopy,Quantum Chemistry,Pyrrole,IR Cavity Ringdown Spectroscopy,Hydrogen Bonds,Molecular Structure,Pseudorotation
更新于2025-09-19 17:13:59
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Determination of pH Dependent Structures of Thymol Blue Revealed by Cooperative Analytical Method of Quantum Chemistry and Multivariate Analysis of Electronic Absorption Spectra
摘要： The pH dependent structure of thymol blue (TB) in solution, a long-standing controversial issue, has been determined by quantum chemistry with an aid of multivariate analysis of electronic absorption spectra. It has been revealed that the TB structure varies from the neutral biprotonated form with open-sulton ring showing red to the monovalent anion of the pure quinoid form showing yellow and then to the quinoid-phenolate form showing blue on raising the pH for a solution.
关键词： Molecular structure analysis,Chemometrics,Acid-base indicator
更新于2025-09-16 10:30:52
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Infrared attenuated total reflection spectroscopic analysis and quantitative detection of forage spectral features in ruminant systems
摘要： This study aimed to (1) access protein molecular structure profile and metabolic characteristics of model forages [Foreign sourced-origin (coded as: “FSO”, n = 7 vs. Chinese sourced-origin alfalfa hay “CSO”, n = 5] in ruminant systems; (2) Quantify the relationship between forage protein molecular structures and protein utilization and availability. Advanced non-invasive vibrational molecular spectroscopic technique (ATR-FTIR: Attenuated Total Reflection Fourier Transform Infrared spectroscopy) with chemometrics was applied to reveal forage protein molecular structure. Both univariate and multivariate molecular spectral analyses were applied to study molecular structure features in model forages. The molecular structure study provided the detailed protein structure profiles of Amide I and Amide II areas and height, total Amide I and II area ratios, Amide I to II height ratio as well as Amide I to II area ratio using ATR-FTIR spectroscopy. The results showed FSO and CSO had similar (P > 0.05) protein rumen degradation kinetics. However, FSO had superior quality than CSO in intestinal (IDP) and total digestible protein (TDP) and truly absorbed nutrient supply (P < 0.05). As intestinal digestion of protein, FSO was higher (P < 0.05) in protein digestion in terms of: intestinal digestibility of rumen undegraded protein (dIDP: 47.5 vs. 38.3 %RUP); Intestinal digestible protein (IDP: 17.6 vs. 13.7 %CP). As truly absorbed nutrient supply, FSO contained higher (P < 0.05) truly absorbed rumen synthesized microbial protein, absorbable rumen undegradable feed protein in the small intestine, total truly digested protein in the small intestine, metabolizable protein and Feed Milk Value (FMVDVE: 1.2 vs. 1.1 g/kg DM). The molecular structure-nutrition interactive relationship study showed that protein molecular structure profiles were highly associated to protein rumen degradation kinetics, significantly correlated to protein subfractions, protein intestinal digestion, and truly absorbed nutrient supply in ruminant systems.
关键词： Vibrational molecular spectroscopy-ATR-FTIR,Intestine digestion,Model forages,Truly absorbed protein supply,Rumen degradation,Protein molecular structure and conformation,Univariate and multivariate molecular spectral analyses
更新于2025-09-12 10:27:22