The present study aims at enhancing the aesthetic durability of Zisha teapots by dip coating green-synthesized TiO2 nanoparticles using Panax Ginseng leaf extract. The TiO2 nanoparticles were characterized using UV-Vis spectroscopy, FTIR spectroscopy, XRD, and TEM, and found to be anatase-phase spherical-shaped particles with a size of <5 nm. The successful coating of TiO2 nanoparticles was confirmed by XRD, SEM, and EDX investigations. The surface of the coated Zisha teapots was patchy with the distribution of TiO2 compared to the uncoated Zisha teapots. The TiO2 nanoparticles and coated Zisha teapots exhibited excellent photocatalytic decolorization of tea extracts in the presence of sunlight with 100% efficiency. The kinetic modelling of the photocatalysis data revealed the applicability of the pseudo-first-order kinetic model with a faster reaction rate and a shorter half-life of 23.7 min. The TiO2 nanoparticles exhibited excellent antimicrobial activity against Bacillus subtilis and Staphylococcus aureus and moderate activity towards Escherichia coli and Klebsiella pneumoniae. The wear resistance experiments revealed the ability of the TiO2 nanoparticles to resist the abrasion of Zisha teapots by 50%. The combined results of this study highlight the ability of the Zisha teapots coated with TiO2 nanoparticles to self-clean the tea stain and thus enhance the aesthetic durability of Zisha teapots.
Machine learning (ML) based methods and tools have now firmly established themselves in physical chemistry and in particular in theoretical and computational chemistry and in materials chemistry. The generality of popular ML techniques such as neural networks or kernel methods (Gaussian process and kernel ridge regression and their flavors) permitted their application to diverse problems from prediction of properties of functional materials (catalysts, solid state ionic conductors, etc.) from descriptors to the building of interatomic potentials (where ML is currently routinely used in applications) and electron density functionals. These ML techniques are assumed to have superior expressive power of nonlinear methods, and are often used "as is", with concepts such as "non-parametric" or "deep learning" used without a clear justification for their need or advantage over simpler and more robust alternatives. In this Perspective, we highlight some interrelations between popular ML techniques and traditional linear regressions and basis expansions and demonstrate that in certain regimes (such as a very high dimensionality) these approximations might collapse. We also discuss ways to recover the expressive power of a nonlinear approach and to help select hyperparameters with the help of high-dimensional model representation and to obtain elements of insight while preserving the generality of the method.
Chemistry in Titan’s N 2 -CH 4 atmosphere produces complex organic aerosols. The chemical processes and the resulting organic compounds are still far from understood, although extensive observations, laboratory, and theoretical simulations have greatly improved physical and chemical constraints on Titan’s atmosphere. Here, we conduct a series of Titan atmosphere simulation experiments with N 2 -CH 4 gas mixtures and investigate the effect of initial CH 4 ratio, pressure, and flow rate on the production rates and composition of the gas and solid products at a Titan relevant temperature (100 K) for the first time. We find that the production rate of the gas and solid products increases with increasing CH 4 ratio. The nitrogen-containing species have much higher yield than hydrocarbons in the gas products, and the N/C ratio of the solid products appears to be the highest compared to previous plasma simulations with the same CH 4 ratio. The greater degree of nitrogen incorporation in the low temperature simulation experiments suggests temperature may play an important role in nitrogen incorporation in Titan’s cold atmosphere. We also find that H 2 is the dominant gas product and serves as an indicator of the production rate of new organic molecules in the experiment, and that CH 2 NH may greatly contribute to the incorporation of both carbon and nitrogen into the solid particles. The pressure and flow rate affect the amount of time of the gas mixture exposed to the energy source and therefore impact the N 2 -CH 4 chemistry initiated by the plasma discharge, emphasizing the influence of the energy flux in Titan atmospheric chemistry.
In this study, a two-layered thin-film structure consisting of a dispersed nanoscaled Ag2O phase and SnO2 layer (SA) and a mono-composite film layer (CSA) consisting of a nanoscale Ag2O phase in the SnO2 matrix are designed and fabricated for NO2 gas sensor applications. Two-layered and mono-layered SnO2–Ag2O composite thin films were synthesized using two-step SnO2 and Ag2O sputtering processes and Ag2O/SnO2 co-sputtering approach, respectively. In NO2 gas-sensing measurement results, both SA and CSA thin films that functionalized with an appropriate Ag2O content exhibit enhanced gas-sensing responses toward low-concentration NO2 gas in comparison with that of pristine SnO2 thin film. In particular, a gas sensor made from the mono-composite SnO2–Ag2O layer demonstrates apparently higher NO2 gas-sensing performance than that of double-layered SnO2–Ag2O thin-film sensor. This is attributed to substantially numerous p–n junctions of Ag2O/SnO2 formed in the top region of the SnO2 matrix. The gas-sensing response of the optimal sample (CSA270) toward 10 ppm NO2 gas is 5.91, and the response/recovery speeds in a single cycle dynamic response plot are 28 s/168 s toward 10 ppm NO2, respectively. Such a p–n thin-film configuration is beneficial to induce large electric resistance variation before and after the introduction of NO2 target gas during gas-sensing tests. The experimental results herein demonstrate that the gas-sensing performance of p–n oxide composite thin films can be tuned via the appropriate design of composite thin-film configuration.
In this study, we propose a highly accurate catalyst evaluation method by improving the time-zero analysis, which has been reported as an activity evaluation method for gas evolution powder catalysts. We refined the extrapolation approach to plot in this study’s time-zero analysis as an analytical method. The Tafel slopes obtained with this method for LaNiO3 (LNO) were found to be within the reported range, and the data was consistent in catalytic loading range of 2.5–3.3 mg-LNO cm−2. Using the improved time-zero analysis, the kinetic activity of the gas evolution powder catalyst is possible to be evaluated with high accuracy.
A recent development in quantum chemistry has established the quantum mutual information between orbitals as a major descriptor of electronic structure. This has already facilitated remarkable improvements in numerical methods and may lead to a more comprehensive foundation for chemical bonding theory. Building on this promising development, our work provides a refined discussion of quantum information theoretical concepts by introducing the physical correlation and its separation into classical and quantum parts as distinctive quantifiers of electronic structure. In particular, we succeed in quantifying the entanglement. Intriguingly, our results for different molecules reveal that the total correlation between orbitals is mainly classical, raising questions about the general significance of entanglement in chemical bonding. Our work also shows that implementing the fundamental particle number superselection rule, so far not accounted for in quantum chemistry, removes a major part of correlation and entanglement seen previously. In that respect, realizing quantum information processing tasks with molecular systems might be more challenging than anticipated.
Historically, the field of radiation chemistry began shortly after the discovery of radioactivity, and its development has been closely related to discoveries in other related fields such as radiation and nuclear physics. Radiolysis of water and radiation chemistry have been very important in elucidating how radiation affects living matter and how it induces DNA damage. Nowadays, we recognize the importance of chemistry to understanding the effects of radiation on cells; however, it took several decades to obtain this insight, and much is still unknown. The radiolysis of water and aqueous solutions have been the subject of much experimental and theoretical research for many decades. One important concept closely related to radiation chemistry is radiation track structure. Track structure results from early physical and physicochemical events that lead to a highly non-homogenous distribution of radiolytic species. Because ionizing radiation creates unstable species that are distributed non-homogenously, the use of conventional reaction kinetics methods does not describe this chemistry well. In recent years, several methods have been developed for simulating radiation chemistry. In this review, we give a brief history of the field and the development of the simulation codes. We review the current methods used to simulate radiolysis of water and radiation chemistry, and we describe several radiation chemistry codes and their applications.
This monograph presents the process of charge transfer in the traditionally independent fields of physics, chemistry and biology from a unified point of view. The numerous facets of charge transfer are presented coherently, emphasizing the common nature of phenomena which at first sight appear quite different. Detailed theoretical overviews are presented and phenomena such as redox, electrochemical and radiative processes, polarons, proton transfer and biological processes are discussed. All major results of the different processes in physics, chemistry and biology are discussed in detail with reference to their physical mechanisms, thereby allowing a unified conceptual approach to be applied. This unified approach to charge transfer science provides a useful tool for the increasing number of theoretical and experimental scientists involved in such areas as physical chemistry, electrochemistry, chemical physics, biophysics, biochemistry, solid-state and surface physics.
In this work, the corrosion mechanism of X80 steel under AC interference was studied with electrochemical measurements. The surface potential was monitored at various AC current densities. EIS (electrochemical impedance spectroscopy) measurements were conducted at various AC voltage amplitudes and for various time durations. Variations in the modulus values of the real part and imaginary part were studied. In addition, to simplify the problem, EIS was measured under the effect of various DC potentials. The surface potential was of the same frequency as the AC interference, and the amplitude of the electrode surface potential was linear with the applied current density. As the AC current density increased, the charge transfer resistance decreased due to the acceleration of both the anodic and cathodic processes. When the AC current density reached a certain value, hydrogen and oxygen evolution occurred because the effective Faraday potential exceeded the corresponding critical reaction potential. With an increasing AC time, the charge transfer resistance increased, which was due to the formation of a protective corrosion product film. With the application of low-amplitude AC voltages, there was only a small change in the capacitance of the electric double layer. Nevertheless, with the application of AC voltages at higher amplitudes, the modulus values of the real and imaginary parts of EIS were all less rapid, and the ratio of the imaginary part and real part decreased.
Industrial electrochemistry, Physical and theoretical chemistry
Salinity gradient energy generated by the contact between seawater and river water is one of the promising renewable energies. In the reverse electrodialysis (RED), salinity gradient energy is directly translated into the electricity. The representative problem is a large electrical resistance of river water or dilute solutions. The dilute solutions are poor electrically conductive. This results in a huge energy loss when an electrical current passes through it.In this study, sodium chloride (NaCl) or poly(sodium 4-styrenesulfonate) (NaPSS) was added to the dilute solutions to increase the conductivities and enhance the power outputs of the RED cells. When NaCl was added, the power output reached 11.4 ± 0.6 µW. On the other hand, when NaPSS was added, the power output increased up to 19.6 ± 0.6 µW.
Vitamin C is an important human micronutrient. It has many vital biological functions in human health. In this research paper, the molecule of vitamin C was optimized and energy band gaps were determined using DFT and HF methods. In computational quantum theory, Density Functional Theory (DFT) and Hartree-Fock (HF) currently play a significant role in physical chemistry spatially. We chose a 6-311+G basis set on the DFT and HF methods to assess our vitamin C molecule. The FT-IR spectra of vitamin C are reported in the current research. The observed vibrational frequencies are assigned and the computational calculations are performed and the corresponding results are displayed. The structure analysis of the present molecule was investigated by NMR (13C NMR & 1H NMR) and UV-Vis spectra. To assess molecular behavior, Mulliken charge distribution, molecular electrostatic potentials (MEP) and Molecular reactivity description were informed to define the activity of the molecule. All calculations were performed using Gaussian 09 packages.
To achieve the accumulation of targeted secondary metabolites, microorganisms must adopt various protection mechanisms to avoid or reduce damage to cells caused by abiotic stresses, which formed from the changes of physical and chemical culture conditions. The protection mechanism of Monascus sp. to tolerate high-concentration ammonium chloride was analyzed by sequential window acquisition of all theoretical mass spectra-mass spectrometry proteomics in this work, and the results indicated that abiotic stresses caused by high-concentration ammonium chloride inhibited the synthesis of chitin and glycoprotein, leading to a decrease in cell wall integrity and, thus, affecting cell growth. At the same time, it also inhibited the complex enzyme III and IV activities of the mitochondrial cytochrome respiratory chain, leading to an increase in reactive oxygen species (ROS) levels. With the aim to respond to abiotic stresses, the cross-protection mechanism was implemented in Monascus, including self-protection of the Monascus cell by promoting synthesis of trehalose, a molecular chaperone that facilitates protein folding (such as heat-shock protein) and autophagy-related proteins, through not the enzyme protection system (superoxide dismutase, peroxidase, catalase, NADPH oxidase, and alternative oxidase) but the glutathione/glutaredoxin system, to maintain the intracellular redox state and then eliminate or reduce ROS damage to the cell. At the same time, an alternative respiratory pathway related to NADH dehydrogenase was activated to balance the material and energy metabolism.