Dielectric study on membrane adsorption and release: Relaxation mechanism and diffusion dynamics

Dielectric monitoring of the adsorption or release process of salicylic acid (SA) by chitosan membrane shows that the dielectric spectra of the chitosan membrane/ SA solution systems change regularly in the adsorption or release process. By analyzing the regularity, a new mechanism for the relaxations is proposed. The concentration polarization layer (CPL) caused by SA adsorption or release is confirmed to be essential for the dielectric relaxations. The changes of the spectra with time are explained by account of the relationship between CPL properties and dielectric strength. Based on this relaxation mechanism, a theoretical method can be established to calculate dynamical parameters of inner structure of the adsorption or release systems from their dielectric spectra. Therefore, dielectric spec- troscopy is demonstrated to be a promising method for estimating interfacial distribution of ionic sub- stances and their binding to membrane in a non-invasive way.     

Improvement in the detection of impurities affecting ethylene glycol UV transmittance by gas chromatography-mass spectrometry

A method was developed for the detection of trace impurities affecting ethylene glycol UV transmittance, using gas chromatography-mass spectrometry in the selective ion monitoring mode. Four 1,2-cyclopentanediones were identified in commercial ethylene glycol as well as in several ethylene glycol plant streams, including 3-methyl-1,2-cyclopentanedione, 3,5-dimethyl-1,2-cyclopentanedione, 3,4-dimethyl-1,2-cyclopentanedione and 3-ethyl-1,2-cyclopentanedione. Quantification of the first three compounds was achieved by monitoring the molecular ion. This method requires no sample preparation and can detect the compounds of interest as low as 0.1 microg ml(-1). As a simple and rapid method, it can be used in tracing these 1,2-cyclopentanediones in glycol plants.     

A Barzilai-Borwein conjugate gradient method

The linear conjugate gradient method is an optimal method for convex quadratic minimization due to the Krylov subspace minimization property. The proposition of limited-memory BFGS method and Barzilai-Borwein gradient method, however, heavily restricted the use of conjugate gradient method for large-scale nonlinear optimization. This is, to the great extent, due to the requirement of a relatively exact line search at each iteration and the loss of conjugacy property of the search directions in various occasions. On the contrary, the limited-memory BFGS method and the Barzilai-Bowein gradient method share the so-called asymptotical one stepsize per line-search property, namely, the trial stepsize in the method will asymptotically be accepted by the line search when the iteration is close to the solution. This paper will focus on the analysis of the subspace minimization conjugate gradient method by Yuan and Stoer (1995). Specifically, if choosing the parameter in the method by combining the Barzilai-Borwein idea, we will be able to provide some efficient Barzilai-Borwein conjugate gradient (BBCG) methods. The initial numerical experiments show that one of the variants, BBCG3, is specially efficient among many others without line searches. This variant of the BBCG method might enjoy the asymptotical one stepsize per line-search property and become a strong candidate for large-scale nonlinear optimization.     

Mg(NH2)2与LiH放氢反应机理的密度泛函理论研究

采用密度泛函理论B3LYP方法研究Mg(NH₂)₂与LiH放氢反应机理,在6-311G(d,p)基组水平上对反应物、中间体、过渡态及产物进行全几何参数优化,频率分析和内禀反应坐标(IRC)计算证实中间体和过渡态的正确性和相互连接关系.计算结果表明,反应分三个阶段,包括第一步氢取代反应,第二步氢取代反应和脱氢后的异构化反应.反应有两条途径,其中第二步对位氢取代反应所对应通道为主反应通道.反应释放的H₂中两个氢原子分别来源于Mg(NH₂)₂和LiH.     

Theoretical study on the reaction of CN radicals with ClO radicals by density functional theory

The reaction mechanism of CN radicals with ClO radicals has been studied theoretically using ab initio and density functional theory (DFT). The result shows that the main reaction path is the O atom in radical ClO attacks the C atom in radical CN to compose the intermediate 1 ClOCN. Three thermodynamically accessible prodncts, P₁ (CO+ClN), P₃ (NO+CCl), and P₄ (ClNCO), were obtained from intermediate 1 through isomerization and decomposition reactions. P₄ is the primary product, and P₁ and P₃ are the secondary product. Compared with the singlet potential energy surface, the contribution of the triplet potential energy surface can be ignored.     

An inkjet printing soft photomask and its application on organic polymer substrates

This article presents a simple, fast and low-cost method to fabricate a flexible UV light photomask. The designed micropatterns were directly printed onto transparent hybrid composite film of biaxially oriented polypropylene coated with silica oxide (BOPP-SiO _x ) by an inkjet printer. Compared to the conventional chrome-mask, it is of advantages such as suitable for non-planar substrates, scalable for large area production, and extreme low cost. Combined with the confined photo-catalytic oxidation (CPO) reaction, the printed flexible BOPP-SiO _x photomask was successfully used to pattern the shape of wettability of organic polymer surfaces, and then polyaniline patterns were deposited on the modified substrates with strong adhesion. With the above photomasks, the polyacrylic acid graft chains were duplicated on the poly (ethylene terephthalate) (PET) and BOPP substrates by photografting polymerization. We grafted polyacrylic acid (PAA) on a non-planar plastic substrate with this soft and thin plastic photomask. Scanning electron microscopy (SEM) and optical microscopy were used to characterize the surface morphology and thickness of ink layers of the printed photomask. Optical microscopy was used to characterize the deposition polyaniline micropatterns. It was found that the desired patterns were precisely printed on the modified polymer films and were applied in modifying organic polymer substrates. The printed photomask could be exploited in the fields such as prototype microfluidics, micro-sensors, optical structures and any other kind of microstructures which does not require high durability and dimensional stability.     

Passive Immunization of Crayfish (<Emphasis Type="Italic">Procambius clarkiaii</Emphasis>) with Chicken Egg Yolk Immunoglobulin (IgY) Against White Spot Syndrome Virus (WSSV)

White spot syndrome virus (WSSV) is a major cause of mortality in shrimp lacking a true adaptive immune response. In this study, high activity egg yolk immunoglobulin (IgY) against WSSV for passive immunization of crustaceans was already prepared as crude and purified product, while an indirect enzyme-linked immunosorbent assay test was used for quality control of IgY activity. The effectiveness of IgY of intramuscular injection, oral administration, and immersion was investigated in crayfish (Procambius clarkiaii) against WSSV. The result showed that the groups treated with IgY from inactivated WSSV and DNA vaccine were, respectively, 20% and 80% mortality, which were significant difference in survival rates (P < 0.05) from the positive control groups. The groups in diet added 10% egg yolk powder and 1% IgY power showed 53.3% and 67.7% mortality, respectively, and the immersion showed 46.7% mortality, which have significantly different compared to the positive groups (P < 0.05). These results indicated passive immunization of specific IgY antibodies through intramuscular injection, oral administration, and immersion have effective to protect crayfish against WSSV. It is noteworthy that IgY as feed additive and immersion solution is useful and feasible methods in practical work. Thus, our results suggest that the passive immunization of crayfish with IgY against WSSV will have potential development to prevent and control WSSV in practical culture.     

A Stochastic Approximation Frame Algorithm with Adaptive Directions

Stochastic approximation problem is to find some root or extremum of a non- linear function for which only noisy measurements of the function are available.The classical algorithm for stochastic approximation problem is the Robbins-Monro (RM) algorithm,which uses the noisy evaluation of the negative gradient direction as the iterative direction.In order to accelerate the RM algorithm,this paper gives a flame algorithm using adaptive iterative directions.At each iteration,the new algorithm goes towards either the noisy evaluation of the negative gradient direction or some other directions under some switch criterions.Two feasible choices of the criterions are pro- posed and two corresponding flame algorithms are formed.Different choices of the directions under the same given switch criterion in the flame can also form different algorithms.We also proposed the simultanous perturbation difference forms for the two flame algorithms.The almost surely convergence of the new algorithms are all established.The numerical experiments show that the new algorithms are promising.     

A binder- and carbon-free hydrogen evolution electro-catalyst in alkaline media based on nitrogen-doped Ni(OH)2 nanobelts/3D Ni foam

Journal of Nanoparticle Research - The ground-state magnetic properties of ConPtm binary alloy clusters of size N = n + m ≤?9 are studied systematically as a function of size,...     

Dynamic simulation on the temperature field of laser micro-patterning metal in the liquid

To further understand the mechanism of laser electrochemical etching metal, it is necessary to describe the temperature field induced by laser heating metal at the liquid–solid interfaces. For solving the complex problem of laser heating a metal immersed in a liquid, the thermal phenomena adjacent to the metal–liquid interface, which was induced by means of irradiating a stainless steel sample immersed in a liquid with an 808 nm semiconductor laser beam, were numerically investigated. Based on a simplified method to solve the transient explosive boiling when a continuous wave (CW) laser heating a material in a liquid, a commercial finite element analysis (FEA) code (ABAQUS) was used to directly solve and model the transient temperature fields of laser micro-patterning metal in a liquid. As known from simulation results, the simulation of laser scanning indicates that it realizes the effect of pulse laser heating owing to laser moving and liquid cooling. Moreover, laser scanning achieves the pattern at a high resolution. At the same time, the experiment phenomena also proved that the simulation results were reasonable.