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Next‐generation quantum theory of atoms in molecules for the ground and excited state of the ring‐opening of cyclohexadiene
摘要： The factors underlying the experimentally observed branching ratio (70:30) of the (1,3-cyclohexadiene) CHD ! HT (1,3,5-hexatriene) photochemical ring-opening reaction are investigated. The ring-opening reaction path is optimized by a high-level multi-reference DFT method and the density along the path is analyzed by the quantum theory of atoms in molecules (QTAIM) and stress tensor methods. The performed density analysis suggests that, in both S1 and S0 electronic states, there exists an attractive interaction between the ends of the fissile σ-bond of CHD that steers the ring-opening reaction predominantly in the direction of restoration of the ring. It is suggested that opening of the ring and formation of the reaction product (HT) can only be achieved when there is a sufficient persistent nuclear momentum in the direction of stretching of the fissile bond. As this orientation of the nuclear momentum vector can be expected relatively rare during the dynamics, this explains the observed low quantum yield of the ring-opening reaction.
关键词： QTAIM,ring-opening,cyclohexadiene,conical intersection,stress tensor
更新于2025-09-23 15:23:52
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Surface-interface analysis of In <sub/>x</sub> Ga <sub/>1-x</sub> As/InP heterostructure in positive and negative mismatch system
摘要： The change of In content in the InxGa1-xAs/InP system leads to the variation of the lattice constant and thereby to the negative mismatch between the base InP and the positive mismatch. Here, we studied the surface morphology and dislocation relationship of InxGa1-xAs/InP (100) in the positive and negative mismatch system by different characterization techniques. Under the same mismatch, the surface morphology and mass effect of negative mismatch were greater than those of positive mismatch. The reason was that in the negative mismatch system, during the film growth, the disorder degree at the interface increases, leading to an increase in dislocation density, meanwhile, the dislocation in the substrate more easily moved into the film, thus increasing the film and the dislocation density in it. Moreover, the mechanism of the buffer layer was also clarified. The addition of the buffer layer first limited the dislocation movement in the substrate, and secondly reduced the mismatch between the epitaxial layer and the substrate, thereby reducing mismatch dislocation.
关键词： surface/interface,lattice mismatch,InxGa1-xAs/InP,residual stress,dislocation
更新于2025-09-23 15:23:52
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Metal accumulation, biochemical and behavioral responses on the Mediterranean clams Ruditapes decussatus exposed to two photocatalyst nanocomposites (TiO2 NPs and AuTiO2NPs)
摘要： Nanoparticle decoration with noble metal represents a promising alternative to improve their photocatalytic and photovoltaic properties. However, toxicity can be influenced by such modification, as the bioavailability of these substances may be influenced. To understand how decoration influences the NP impacts in marine ecosystems, we exposed suspension-feeding clams, Ruditapes decussatus, to two photocatalyst nanocomposites, TiO2 NPs and AuTiO2 NPs, over 2 concentrations, 50 μg L?1 and 100 μg L?1, in a laboratory experiment. Accumulation of Au and Ti in gills and digestive gland was noted in clams after exposure to TiO2 NPs and AuTiO2 NPs using inductively coupled plasma optic emission spectroscopy (ICP-OES). TiO2 and AuTiO2 NPs alter the behavior of the clams Ruditapes decussatus by reducing filtration and respiration rates. Furthermore, the highest concentration of TiO2NPs induces an overproduction of H2O2 in gills and digestive gland and NO production only in gills. Superoxide dismutase (SOD), Catalase (CAT), Glutathione-S-transferase (GST) and acetylcholinesterase (AChE) activities were induced in gills and digestives gland in concentration and nanocomposite type dependent manner. Decorated form presented higher Malondialdehyde (MDA) levels in gills and digestive gland than the undecorated form, suggesting different mechanisms of action that may be mediated through oxidative stress. In conclusion, the considered parameters could represent reliable biomarkers for the assessment of NP toxicity on R. decussatus as biological biomonitoring model. In addition, based on the obtained results, nanoparticle decoration influences the toxicity of metal nanoparticles in marine organism.
关键词： Oxidative stress,Ruditapes decussatus,Biomarkers,TiO2 NPs,AuTiO2NPs
更新于2025-09-23 15:23:52
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Behavior of Al/Cu/Ti electrodes in surface acoustic wave filter at high power
摘要： Driven by the need for high data-rates and continuous reduction in device size, surface acoustic wave filters are required to work under increasingly high power. In this work, a series of 2.7 GHz surface acoustic wave filters with Al/Cu/Ti three-layered electrode were fabricated and loaded with high power. Those three-layered electrodes showed weaker texture but higher stability than Al-Cu alloy electrode at high power. Morphologies, microstructures and elements distribution in cross section of fingers were analyzed carefully before and after high power loading. Results show that the circular-arc-shaped outline of fingers were appeared in most samples after high power loading, and the number of gains in the finger cross section changed from some into several with much larger volume. The features of distribution of Cu atoms also coincided with these microstructures. By finite element method and phase diagram analysis, the higher stability of Al/Cu/Ti three-layered electrodes are attributed to precipitation of θ-CuAl2 in the bottom edge of electrode finger and Cu-doped α-Al in the center top.
关键词： stress,Al-Cu alloy,high power,surface acoustic wave filter,three-layered electrode
更新于2025-09-23 15:23:52
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Dislocation bending and stress evolution in Mg-doped GaN films on Si substrates
摘要： P-type doping using Mg is essential for realizing a variety of electronic and optoelectronic III-nitride devices involving hetero-epitaxial thin films that also contain a significant number of dislocations. We report on the effect of Mg incorporation on dislocation and stress evolution during the growth of GaN thin films by using in situ curvature measurements and ex situ transmission electron microscopy. A complete picture involving the interplay between three effects—dopant size effect, dislocation bending, and polarity inversion—is presented. Mg aids dislocation bending, which in turn generates tensile stresses in Mg-doped GaN films. As a result, the compressive stress expected due to the dopant size difference effect can only be discerned clearly in films with dislocation densities below 5 × 10^9 cm^?2. Polarity inversion at doping exceeding 10^19 cm^?3 is associated with a sharp drop in screw dislocation density. A kinetic stress evolution model has been developed to capture dislocation bending and size difference effects, and a match between calculated bending angle from the model and that measured from TEM images is obtained.
关键词： Mg doping,stress evolution,dislocation bending,in situ curvature measurements,transmission electron microscopy,polarity inversion,GaN
更新于2025-09-23 15:23:52
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Effect of external stresses on the optical and electronic properties of potassium dihydrogen phosphate crystals
摘要： Potassium dihydrogen phosphate (KDP) has been extensively used in electro-optic switches and laser spectroscopy in modulating the frequency of laser radiation. When making refined optical KDP components for such applications, the external stresses in the manufacturing process can introduce changes in their optical and electronic properties. With the aid of the ab initio density functional theory analysis, this paper investigates the effect of stresses on the absorption coefficient, band gap, refractive index, dielectric function and Plasmon energy. It was found that the stress-induced variations in these properties are due to a change of KDP molecular structures. The microstructural changes induced by the uniaxial (along the <110> direction) or by the biaxial (<100> and <010> directions) or by the triaxial (<100>, <010> and <001> directions) tensile stresses bring about significant changes in the optical and electronic properties of KDP.
关键词： Density functional theory,Potassium dihydrogen phosphate,optical properties,stress
更新于2025-09-23 15:23:52
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[IEEE 2018 Second International Conference on Inventive Communication and Computational Technologies (ICICCT) - Coimbatore (2018.4.20-2018.4.21)] 2018 Second International Conference on Inventive Communication and Computational Technologies (ICICCT) - Futuristic Surveillance Spectacles
摘要： Nowadays, spectacles are common which are used to flaunt off your style and stand out among the others in a crowd. But why not disguise some special features within it apart from the style and eye power? There have been many attempts to enhance the way we use our daily commodities in order to expand its range of effectiveness. And so, we strive for further utilizing the spectacles not only as a wearable device but also as a productive device. We propose for a surveillance spectacle which is both swanky and with some extra applications. One of the feature is a camera incorporated at the nose bridge of a spectacle to capture images or videos of the nearby surroundings. This can be used as a hands-free camera for personal as well as for professional purposes. Also, the camera along with a lens can be used as a projector for displaying the captured images/videos. We have further implemented a Bluetooth module which can be linked to any wireless printer so as to print out any images. Finally, the most interesting of all, we have made an attempt to add a stress measurement algorithm through which any human eye's stress can be calculated and will further indicate users about the amount of stress on the eye indirectly cautioning them to give some rest to the eye if it is in a humongous amount of stress. Therefore, this concept is what we believe will improve human life and build up a user-friendly environment.
关键词： Stress Management,Bluetooth Module,Printing,Cornea,Projection
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE International Symposium on the Physical and Failure Analysis of Integrated Circuits (IPFA) - Singapore (2018.7.16-2018.7.19)] 2018 IEEE International Symposium on the Physical and Failure Analysis of Integrated Circuits (IPFA) - Elimination of the Hump Current of P-Channel Polycrystalline Silicon Thin-Film Transistor After Positive Bias Stress
摘要： The stability of p-channel low-temperature polycrystalline silicon (LTPS) thin-film transistors (TFTs) under positive bias stress (PBS) is investigated in this paper. Interestingly, it is observed that the transfer curves show different degradation phenomena from the previous reports, i.e., the threshold voltage (Vth) shifts to the negative gate bias direction, and the hump current in the subthreshold region clearly shrinks with the increase of the stress time, and finally disappears under the PBS, which is explained by the creation and accumulation of positive charges in the gate oxide. It is also observed that the hump current in p-channel TFTs is eliminated at a higher temperature and one possible mechanism for the appearance of hump current is proposed.
关键词： thin-film transistors,positive bias stress (PBS),hump current,p-channel
更新于2025-09-23 15:23:52
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Kink Suppression and High Reliability of Asymmetric Dual Channel Poly-Si Thin Film Transistors for High Voltage Bias Stress
摘要： Asymmetrically designed polycrystalline silicon (poly-Si) thin film transistors (TFT) were fabricated and investigated to suppress kink effect and to improve electrical reliability. Asymmetric dual channel length poly-Si TFT (ADCL) shows the best reduction of kink and leakage currents. Technology computer-aided design simulation proves that ADCL can induce properly high voltage at floating node of the TFT at high drain-source voltage (VDS), which can mitigate the impact ionization and the degradation of the transconductance of the TFT showing high reliability under the hot carrier stress.
关键词： kink,reliability,TFT,hot carrier stress,poly-Si
更新于2025-09-23 15:23:52
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Effect of laser forming on mechanical properties of multiple-phase steels by using a thermal–microstructure–mechanical model
摘要： Based on a forming temperature-controlled mixed strain-hardening law, a temperature-controlled thermal–microstructure–mechanical model was developed to predict the deformation in ferrite–martensite dual-phase steel before and after complex laser forming. Phase transformation in dual phase steel was predicted by coupling a kinetic transformation model with the developed model during laser forming. The corresponding algorithm of the constitutive model was used in three-dimensional finite element method to simulate the material deformation and mechanical properties during the laser forming. The simulated results agree well with the experimental results. Laser forming influences the mechanical properties of the material significantly, leads to bending deformation of the scanned sample and induces a ferrite-to-martensite transformation. The influence of scanning line number on the tensile strength and bending deformation of the scanned specimen was investigated. The tensile strength and bending angle are related positively to the number of scanning lines on the sample.
关键词： Stress-strain curve,Phase transformation,Thermal–microstructure–mechanical model,Sheet metal,Laser forming
更新于2025-09-23 15:23:52