Search

The electronic conductivity, Li adsorption energy and Li+ diffusion barrier were improved by the formed interfacial electric field in Ni/Mo2C, which facilitates the ion/electron kinetics.

Regulating the electronic structure plays a positive role in improving the ion/electron kinetics of electrode materials for lithium ion batteries (LIBs). Herein, an effective approach is demonstrated to achieve Ni/Mo

Non-thermal plasma (NTP) is gaining attention as a powerful tool to induce various reactions. The combination of NTP with catalysts has been successfully used to degrade volatile organic compounds (VOCs) for pollution control. In this study, a series of TiO2-C/5A catalysts, synthesized by carbon dots (C-dots) that decorate TiO2 by sol-gel and wetness impregnation methods, were incorporated with a dielectric barrier discharge (DBD) reactor in a single-stage structure to degrade toluene at atmospheric pressure and room temperature. A proton-transfer reaction mass spectrometer and a CO2 analyzer were used to monitor the concentration variations of organic by-products and CO2 online. The effects of input power, mass ratio of C-dots/TiO2 (TiO2/5A (0 wt%), TiO2-C1/5A (2.5 wt%), TiO2-C2/5A (5 wt%), TiO2-C3/5A (10 wt%)), gas flow rate, initial concentration of toluene on the toluene degradation efficiency, and CO2 selectivity were studied. The plasma-catalyst hybrid system could effectively improve the energy efficiency and reaction selectivity, attaining a maximum toluene degradation efficiency of 99.6% and CO2 selectivity of 83.0% compared to 79.5% and 37.5%, respectively, using the conventional plasma alone. Moreover, the generation of organic by-products also declined dramatically, averaging only half as much in plasma alone. The results also indicated that the appropriate amount of C-dot doping could greatly improve the catalyst efficiency in the hybrid plasma system. This is because the interaction between C-dots and TiO2 favors the formation of photoelectron holes and reduces the energy band gap and the recombination rate of photogenerated electron holes, which facilitates the generation of more active species on the catalyst surface, thereby leading to a more effective degradation reaction. These observations will provide guidance for the interaction studies between NTP and catalysts, not only for the exploration of new chemical mechanisms of aromatic compounds, but also for the screening of favorable materials for the desired reactions.

Herein, the first highly enantioselective amination at the C-2 position of 2-perfluoroalkyl-oxazol-5(2H)-ones to phenylazocarboxylates using a (1R,2R)-cyclohexane-1,2-diamine-derived urea–tertiary amine as a bifunctional catalyst is presented. Two efficient asymmetric transformation processes were achieved through the formation of the intermediate 2-(perfluoroalkyl)-oxazol-5(2H)-ones starting from simple amino acids or via the formation of the intermediate phenylazocarboxylates starting from N-acyl arylhydrazines. Both processes resulted in chiral N,O-aminal derivatives with a quaternary center in good yields (up to 91%) with excellent enantioselectivities (up to 99%). These efficient atom-economical strategies lead to the highly enantioselective construction of N,O-acetal derivatives containing perfluoroalkyl and amino moieties.

Soil has always been the most complex biomaterial on the planet. The rapid determination of the components in the soil and their original source is a prerequisite for soil quality, environmental, and human health risk assessments. In this study, the chemical compositions and source apportionment of surface soil samples collected from five sites in Shanghai, China, were successfully investigated using a laboratory-developed laser ablation single-particle aerosol mass spectrometry (LA-SPAMS) instrument combined with an adaptive resonance theory-based neural network algorithm (ART-2a) data-processing method for the first time. In total, more than 35,000 particles, ranging from 200 to 2000 nm, were sized, and around 15-20% of the particles were chemically analyzed by LA-SPAMS to generate both positive and negative mass spectra. The results show that there are significant differences in particle size distribution among the five samples, with peaks of various sizes and different profiles, while all five soil samples contain crustal elements, heavy metals, organic and inorganic components, and so forth. The chemical composition of each sample varied considerably, so different classes of SPAMS particle classes were identified, which were later grouped into seven general categories: EC-rich (containing elemental carbon), secondary components, organic nitrogen, crust, HM (containing heavy metal), PAH (containing polycyclic aromatic hydrocarbons), and NaK-rich particles, based on the dominant marked ions. The composition analysis and source apportionment showed that soil components in different areas have been affected by the local environment, such as local industrial emissions and automobile exhaust, which are usually characterized by varying degrees of mixing between the crust and environmental aerosols. In combination with the ART-2a method, LA-SPAMS enables rapid and direct analysis of soil samples based on real-time single-particle measurements, which will help in understanding the distribution, transport, and fate of the soil components, thus providing new insights into soil-quality assessment. Moreover, the established LA-SPAMS can also be practically applied to other daily inspection tasks, such as rocks, minerals, metals, ceramics, polymers, and other solid materials for ingredient analysis and quality evaluation.

Non-thermal plasma (NTP) is gaining attention as a powerful tool to induce various reactions. The combination of NTP with catalysts has been successfully used to degrade volatile organic compounds (VOCs) for pollution control. In this study, a series of TiO

High-risk human papillomavirus (HR-HPV) infection is a major risk factor for the initiation and progression of cervical cancer (CC). This study aimed to explore the role of histone deacetylase 6 (HDAC6) in HPV-positive CC and the molecules implicated. Differentially expressed genes between HPV-positive and HPV-negative tissues, and differentially expressed microRNAs (miRNAs) in cells after HDAC6 downregulation were identified using microarray analyses. The expression profiles of HDAC6 and miR-199a and their cellular functions were investigated via loss-of-function studies. Xenograft tumors were induced in mice for in vivo studies. HDAC6 and Wnt5a were highly expressed, whereas miR-199a was poorly expressed in HPV-positive CC tissues. Downregulation of HDAC6 reduced proliferation, migration, invasion, and resistance to apoptosis of HPV-positive CC cells. HDAC6 suppressed the transcription of miR-199a, and miR-199a targeted Wnt5a to inactivate the Wnt signaling pathway. Further downregulation of miR-199a blocked the inhibitory effect of HDAC6 silencing on CC cell growth both in vivo and in vitro, whereas further artificial inhibition of Wnt5a inactivated Wnt signaling and blocked the malignant behaviors of CC cells. This study showed that HDAC6 suppresses the transcription of miR-199a and enhances the progression of HPV-positive cervical cancer through upregulation of Wnt5a.

Several experimental studies are required to recognize the thermal performance for different designs of phase change material (PCM) storage systems. In this study, the melting process of paraffin wax was experimentally and numerically studied in a double tube vertical unit. Initially, the storage unit was at 30 oC and an electric heater in the enclosure's center was used to heat the PCM. The heat flux density ranged from 1000 to 1400 W/m2. The solid-liquid interface was tracked and the PCM local temperatures were measured. The numerical model was established to study the influences of convex/concave dimples, nanoparticles, and heat flux densities on the PCM melting process. The numerical model was validated using data from the literature as well as the present experiments, resulting in an excellent agreement. The convex/concave surface decreases the melting time compared to the smooth surface. The minimum melting time occurred at six dimples with a percentage decrease of 15.56% compared to the smooth wall. The melting time reduced by 19%, 16.61%, and 15.82% at 1200 W/m2 in the case of 5 w.t% of SiO2, Al2O3, and CuO nanoparticles, respectively referred to the smooth wall. The charging time was decreased by 11.02% and 21.73% when the input power was increased from 1000 W/m2 to 1200 W/m2 and 1400 W/m2, respectively, in the case of dimples with nanoparticles. The dimples with nanoparticles are suggested for future modeling of the PCM melting process with small and high heat flux.

Acid-catalyzed heterogeneous reaction can lead to potentially multifold increase in secondary organic aerosol (SOA) generation, which may have a greater impact on climate forcing effects. In this study, single particle aerosol mass spectrometry (SPAMS) and scanning mobility particle sizer (SMPS) were applied to perform an online study of the chemical and physical characteristics of the pyrene-coated inorganic seed particle ozonation in a smog chamber to examine the influence of seed acidity on pyrene-SOA formation. Acidic seed particles are made of ammonium sulfate, ammonium bisulfate and sulfuric acid in different proportions. Fs, the inorganic seed composition number, is defined as a ratio of the molar concentration of SO42− to the total molar concentration of SO42− and NH4+ in this study. Suspended pyrene-coated acidic seed particles were generated by the vaporization-condensation method. Homogeneous and heterogeneous reaction products were identified and assigned. The results show that the seed particle acidity can enhance the mass yield, as well as the chemical diversity of pyrene-SOAs, and also dramatically increase the formation of new smaller particles. Kinetic analysis revealed that the first-order reaction rate constant (K) of acidic seed particles was much higher than that of neutral seed particles, with K values for Fs = 0.77 being 1.47 times that of Fs = 0.50 and 2.58 times that of Fs = 0.33. A mechanism for pyrene-SOA formation was also proposed based on real-time monitoring. For neutral seeds, the pyrene ozonation preferred ‘atom attack’ and mainly formed 1-hydroxypyrene; while for acidic seeds, the pyrene ozonation preferred ‘bond attack’ and formed a Criegee intermediate, followed by broken C–O and C–C bonds, thereby resulting in a variety of semi- and low-volatile products. This study presents a rapid analytical method for the combined use of smog chamber, SPAMS, and SMPS to immediately characterize the effect of seed particle acidity on the formation of polycyclic aromatic hydrocarbon SOA, which may deepen our understanding of new particle formation and particle growth in the atmosphere. Therefore, the present study provides a new insight for an in-depth understanding of haze pollution in China.

Secondary organic aerosols (SOAs) have been receiving significant attention because of their significant impacts on air quality and human health. In this study, the influences of nitrogen oxides (NOx) and ammonia (NH

The main challenge of the absorption cycle in automobile air conditioning (A/C) systems is the use of exhaust energy to drive the system at low engine speeds. To obtain a continuous supply of cooling energy from the absorption cycle, the present study highlights a proposal for a numerical investigation of a novel generator design in an absorption system using an H2O-LiBr solution as the working fluid. The generator heat exchanger (H.EX) was divided into several cells filled with multiple types of phase change materials (PCMs) acting as a storage unit. A comprehensive thermal model was developed and validated with experimental data from the literature. The effects of multiple types of PCM, coefficient of performance (COP), and solution temperature were studied at low (1500, 1750, and 2000 rpm) and high (2250, 2500, and 2750 rpm) engine speeds. The results demonstrated that using multiple types of PCM could improve the heat transfer capability, thereby accelerating the melting rate of the PCM. At low engine speeds, exhaust energy could drive the absorption system with COP values of 0.767 and 0.778, while in the case without PCM, exhaust energy could drive COP values of 0.284 and 0.763 for engine speeds of 1500 and 2000 rpm, respectively. At high engine speeds, the system performance was roughly stable with a slight increase in COP values.

The transient melting process of the phase change material (PCM) is controlled by heat conduction and natural convection. Several experimental investigations are essential to understand the heat transfer mechanisms and performance for different designs of PCM thermal storage systems. Therefore, the present study experimentally investigated paraffin wax's melting process in a vertical cylindrical enclosure. The PCM, initially at 30 °C, was heated using an electric heater located at the center of the enclosure. The heat flux density varied to 1300, 1000, and 700 W/m2. Local temperatures of the PCM were measured, and the solid-liquid interface was tracked. A CFD (computational fluid dynamic) model was developed to numerically investigate the melting process with and without considering the convection effect. The CFD model was validated with the current experiments and with data from the literature. A very good agreement was obtained. The results showed that; the melting was initially dominated by conduction at an early stage, and this period increased with a decrease in heat flux. Natural convection was promoted, at a later time, leading to a curved shape of the solid-liquid interface. Numerical results indicated a robust thermal stratification of the molten liquid in the upper half of the storage unit. It was observed that increasing the input power from 700 W/m2 to 1000 W/m2 and 1300 W/m2 decreased the total melting time by 24.82% and 43.58%, respectively. It is recommended for the future modeling of the PCM melting process to consider the convection effect.

Secondary organic aerosols (SOAs) have been receiving significant attention because of their significant impacts on air quality and human health. In this study, the influences of nitrogen oxides (NOx) and ammonia (NH3) on SOA formation from photooxidation of toluene was investigated in the Shanghai university smog chamber. The chemical and physical characteristics of gas-phase products and SOAs from toluene photo-oxidation were characterized using laboratory-developed single photon ionization time-of-flight mass spectrometry, single particle aerosol mass spectrometry, and cavity ring-down aerosol extinction albedo spectroscopy instruments. It was observed that increasing the initial nitrogen oxides ([NOx]0) under low-[NOx]0 conditions enhanced the SOA yield, while increasing [NOx]0 under high-[NOx]0 conditions suppressed the SOA yield. After adding NH3, the number concentration, average SOA diameter, and extinction and scattering coefficients showed an immediate and rapid increase due to the formation of significant amounts of condensable ammonium nitrate and nitrogen-containing (NOC) compounds. Moreover, a simplified reaction mechanism for the photooxidation of toluene initiated by the hydroxyl radical (OH) was believed to follow two reaction channels: minor H abstraction, and major OH addition, which continuously induced the subsequent reactions. The results of this study presented rapid analytical method for the joint use of a smog chamber with on-line analytical instruments to immediately characterize the effects of SOA formation, which will help in understanding the new particle formation and particle growth, and thus provides a new insight for in-depth understanding of the haze pollution in China.

Rare earth–Mg–Ni-based (RE–Mg–Ni-based) La 0.1 Nd 0.075 Mg 0.04 Ni 0.65 Co 0.12 hydrogen storage alloys were rapidly quenched with and without exerting a 0.18 T static magnetic field and investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) studies and various electrochemical measurements. The results show that all samples hold a two-phase structure consisting of La 2 Ni 7 phase and LaNi 5 phase, suggesting that the structure remains unchanged after treatment. Grain refinement, homogeneous composition and increase in La 2 Ni 7 phase abundance are achieved when magnetic field is applied. In comparison to quenched alloys, higher discharge capacities are obtained for the alloys prepared with the aid of magnetic field mainly due to the larger La 2 Ni 7 phase abundance. Cycling stability is improved with increasing quenching rate probably owing to better anti-pulverization ability resulted from refined grain size. Ameliorated electrochemical kinetics of the magnetic field assisted rapidly quenched alloys has been confirmed by potential-step measurements and electrochemical impedance spectroscopy (EIS) tests in accordance with the enhanced electrochemical properties.

Mesoporous ZnO/TiO 2 hollow microspheres have been successfully synthesized by a facile one-step hydrothermal route without any template. The effect of reactants, temperature and hydrothermal time on the morphology and photocatalytic degradation activity has been investigated in details. The hollow microspheres with average diameter of 0.5–2 μm showed time-dependent growth process and consisted of nanoparticles with a diameter of 10–20 nm. The photocatalytic activity of ZnO/TiO 2 hollow microspheres was evaluated via the photocatalytic degradation of methyl orange (MO). Compared with the pristine TiO 2 hollow microspheres or ZnO nanosheets, the ZnO/TiO 2 hollow microspheres produced significantly positive effect on the band-gap energy shift (from 3.16 eV (TiO 2 ) to 2.80 eV (ZnO/TiO 2 )) and photocatalytic degradation (with a high apparent reaction rate of 10.19 × 10 −2 min −1 ) probably owing to the hybrid hollow microsphere morphology and their synergistic catalytic effect.

The prediction of protein secondary structure is of great significance for studying the function of proteins and for making progress in the field of bioinformatics. Since 1951, the secondary structure of predicted proteins has been proposed. After 66 years of development, the prediction method has been continuously optimized, and the accuracy rate has exceeded 80%. Continuous Automated Model Evaluation (CAMEO) gives a prediction of protein tertiary structure evaluation for many current prediction methods, and secondary structure evaluation has not been achieved. In response to this problem, six servers were selected: PSRSM, MUFOLD, SPIDER, RAPTORX, JPRED and PSIPRED to evaluate the predicted secondary structure. The latest released protein from the Protein Data Bank (PDB) was applied just to ensure that the test set is not included in the training set. In the experiments of which protein homology was 30%, 50%, 70% and 90%, the obtained accuracy of PSRSM for Q3 was 91.44%, 88.12%, 90.17% and 87.39%, respectively. And the accuracy is higher than the best server among other prediction serves---MUFOLD, by 3.19%, 1.33%, 2.19% and 1.72%, correspondingly. It is proved that PSRSM has a better prediction quality than other servers for the same kind of homology data, the Sov and boundary accuracy as well. This paper focuses on analyzing the operating methods and corresponding results of various servers, thus, it is safe to say that the prediction of protein secondary structure should be studied on perspectives of big data, templates and deep learning.

Stroke is a worldwide medical emergency and an important issue in stroke research is looking for the early pathophysiological markers which can predict the severity of brain injury. Decreased cerebral blood flow (CBF) has been serving as the most important indicator of ischemic stroke. Particular attention is paid to study the spatio-temporal CBF changes immediately after the onset of stroke in a rat intraluminal filament middle cerebral artery occlusion (MCAO) model and investigation of its correlation with brain infarct volume after 24 h. We implement an on-line laser speckle imaging (LSI) system, which could provide real time high spatio-temporal resolution CBF information before, during, and immediately after the rat MCAO surgery. We found a significant correlation between the affected area with 50% CBF reduction (CBF50) at the first minute after occlusion with the infarct volume. To the best of our knowledge, this is the earliest CBF marker for infarct volume prediction. Based on such a CBF-infarct volume correlation, LSI may be used as a real time guidance for improving the consistency of intraluminal filament MCAO model since the depth of filament insertion could be adjusted promptly and those unsuccessful models could be excluded in the earliest stage.

Intraluminal middle cerebral artery occlusion (MCAO) model in rats has been widely used to mimic human ischemic stroke and serves as an indispensable tool in the stroke research field. One limitation of this model is its high variability in infarct volume. The cerebral blood flow (CBF) information after cerebrovascular occlusion may reflect the availability of collateral circulation, which serves as a key factor for brain infarct volume. Laser speckle contrast imaging (LSCI) is a valuable tool for full-field imaging of CBF with high spatial and temporal resolution. In this paper, we investigated the spatio-temporal changes of CBF in rat MCAO stroke model using our self-developed real-time LSCI system. CBF images of adult male Sprague Dawley rats (n=13) were recorded before surgery, during first 1.5 hours after surgery, and 24 hours after stroke. We compared the CBF changes of different functional vessels during this period. In the ipsilateral hemisphere, CBF of veins and arteries both decreased as expected, while CBF of veins increased after occlusion in the contralateral hemisphere. Moreover, we found a linear correlation between early-stage CBF after occlusion and brain infarct volume, which can be utilized for surgery guidance to improve the uniformity of rat MCAO stroke models.

In this paper, based on a matrix factorization a novel structure is proposed for digital system implementation and adaptive filtering applications. The equivalent state-space realization of such a structure is an input-balanced realization. Like the normalized lattice structure, it contains a series of Givens rotations. This proposed structure is simpler than the normalized structure and can be implemented very efficiently using the Coordinate Rotation Digital Computer (CORDIC) techniques. This canonical parametrization is particularly important for ensuring the bounded input bounded output (BIBO) stability when used for adaptive filtering. Numerical examples show that the proposed structure outperforms the traditional direct-form II (DFII) structures as well as the normalized lattice structure in terms of minimizing parameter sensitivity and hence roundoff noise.