Integrating thermal-concentration smoothed profile with lattice Boltzmann methods for simulating sedimentation of nonisothermal circular particles

A thermal-concentration smoothed profile-lattice Boltzmann method is proposed to study the effect of the concentration field on the dynamic behavior of nonisothermal cylindrical particles during the sedimentation process. The velocity, temperature, and concentration equations are solved using the lattice Boltzmann method. Moreover, the smoothed profile method is employed to enforce the nonslip boundary condition as well as constant temperature and constant concentration boundary conditions at the particles surfaces. Moreover, the Boussinesq approximation is used to couple the velocities, temperatures, and concentrations fields. The proposed combined method is validated by comparing the present numerical results with those found in the literature, showing good consistency. Then, the effect of the concentration buoyancy on the behavior of nonisothermal particles is discussed. In addition, the effect of Prandtl, Schmidt, and thermal Grashof numbers on the settling process is investigated. The results show that, by adding the effect of concentration, the maximum settling velocity of hot particles is reduced more relative to the cold ones; accordingly, the cold particles are settled faster than the hot ones. Finally, the sedimentation of two particles in a container at high thermal Grashof is investigated. It is shown that, at high thermal Grashof, there is an intense competition between the buoyancy force and gravity for the hot particles. The buoyancy flow generated leads to the reversal of the drafting-kissing-tumbling motion of the hot particles, making the particles move upward.     

大分子溶致凝聚过程中的几个分界浓度

按照现代高分子凝聚态物理学观点,高分子溶液按浓度分为:极稀溶液、稀溶液、亚浓溶液、浓溶液、极浓溶液5个层次,各层次间的分界浓度分别称为动态接触浓度、接触浓度、缠结浓度和全高斯链浓度,其中全高斯链浓度由本文作者命名。文中给出各分界浓度的定义,介绍各分界浓度的物理意义,特别说明命名全高斯链浓度的依据。同时详细讨论了不同浓度溶液中大分子链的构象及其变化、链间相互作用的本质和微观图像、以及溶液浓度变化对溶液性质的影响。     

Mathematical modelling of the oxygen uptake kinetics during whole-body endurance exercise and recovery

In this study, we elucidate four different mathematical models of the kinetics of oxygen uptake during whole-body endurance exercise at different intensities and throughout the subsequent recovery periods. We employ the hypothetical inductive–deductive method and forecast four different models for the oxygen kinetic. The VO₂ development using these models compared with experimental results where an elite cross-country skier performed laboratory tests while running with poles on a treadmill, in which the rate of oxygen uptake and blood lactate concentration as a function of time were measured. The most developed model accounted for the delayed superimposed slow component of oxygen uptake and the influence of lactic power production on the oxygen kinetics. The rate of change in oxygen with this model is consistent with the accumulated oxygen deficit model and matched the data well, even for intensities above the lactate threshold and during recovery.     

洗衣粉溶液的实验研究

为了研究洗衣粉溶液的合理使用浓度和温度,利用FD-NST-I型表面张力测定仪测量溶液表面张力系数,同时用pH计进行实验检测。结果表示:0.05%～0.10%的洗衣粉溶液在30.0～45.0℃时表面张力系数较小,更有利于洗净衣物,同时pH值较低,对手及被洗织物都不会产生损害,此区间取值与日常生活习惯相一致。     

High‐resolution slice selection NMR for the measurement of CO2 diffusion under non‐equilibrium conditions

We present a simple and an efficient approach using spatially selective NMR to investigate solvation and diffusion of CO₂ in ionic liquids. The techniques demonstrated here are shown as novel and effective means of studying solvated gas dynamics under non‐equilibrium conditions without the need for conventional high power gradients. Copyright © 2014 John Wiley & Sons, Ltd.     

Heating and temperature gradients of lipid bilayer samples induced by RF irradiation in MAS solid‐state NMR experiments

The MAS solid‐state NMR has been a powerful technique for studying membrane proteins within the native‐like lipid bilayer environment. In general, RF irradiation in MAS NMR experiments can heat and potentially destroy expensive membrane protein samples. However, under practical MAS NMR experimental conditions, detailed characterization of RF heating effect of lipid bilayer samples is still lacking. Herein, using ¹H chemical shift of water for temperature calibration, we systematically study the dependence of RF heating on hydration levels and salt concentrations of three lipids in MAS NMR experiments. Under practical ¹H decoupling conditions used in biological MAS NMR experiments, three lipids show different dependence of RF heating on hydration levels as well as salt concentrations, which are closely associated with the properties of lipids. The maximum temperature elevation of about 10 °C is similar for the three lipids containing 200% hydration, which is much lower than that in static solid‐state NMR experiments. The RF heating due to salt is observed to be less than that due to hydration, with a maximum temperature elevation of less than 4 °C in the hydrated samples containing 120 mmol l^?1 of salt. Upon RF irradiation, the temperature gradient across the sample is observed to be greatly increased up to 20 °C, as demonstrated by the remarkable broadening of ¹H signal of water. Based on detailed characterization of RF heating effect, we demonstrate that RF heating and temperature gradient can be significantly reduced by decreasing the hydration levels of lipid bilayer samples from 200% to 30%. Copyright © 2016 John Wiley & Sons, Ltd.     

Complexation induced by weak interaction between DNA and PEO-b-P4VP below the CMC of the polymer

The complexation between circular DNA and individual chains of PEO-b-P4VP with a relatively long PEO block and a short P4VP block is highly controllable when the interaction between DNA and the polymer is weak enough. When one circular DNA chain is taken into consideration, and the polymer concentration is far below its critical micelle concentration(CMC), polymer chains are absorbed by DNA chain due to the interaction between the negatively charged DNA chain and the slightly positively charged P4VP block chains. After the adsorption/complexation, the DNA chain is converted into a nanoring(type 1). In the nanoring, the DNA chain is sufficiently wrapped by the polymer and adopts a fully stretched conformation, so that the DNA compact ratio in the nanorings is close to 1. When the polymer concentration is close to but lower than the CMC, the free polymer chains in the solution are adsorbed not only by the DNA chain but also by the polymer chains that have already been adsorbed on the DNA chain. As a result, the circular DNA chain adsorbs more polymer chains, and thus the resultant nanoring(type 2) has a larger width. In the type 2 nanoring, the DNA chain is slightly compressed; the DNA compact ratio is only about 2-3. Therefore, complexation induced by the weak interaction between DNA and PEO-b-P4VP below the CMC can produce narrow-disperse and large nanorings with a perimeter of micrometers, which are difficult to prepare by existing methods.     

Synthesis,characterization, and biological activity of some complex combinations of nickel with α-ketoglutaric acid and 1-(o-tolyl)biguanide

The four divalent nickel complexes having α-ketoglutaric acid (H₂A) and 1-(o-tolyl)biguanide (TB) ligands have been synthesized, characterized, and tested for antibacterial and antitumor activity.The proposed formulas for these complexes are [Ni(TB)(HA)(H₂O)₂]Cl (C1), [Ni(TB)(HA)(H₂O)₂]Br (C2), [Ni(TB)(HA)]NO₃·H₂O (C3), and [Ni(TB)(HA)]CH₃COO (C4), where HA represents deprotonated H₂A.For the four complexes and for the ligands used in the synthesis, the antibacterial activity against Staphylococcus aureus ATCC 25923 and Pseudomonas aeruginosa ATCC 27853 and antitumor activity in HeLa tumor cells were tested. A moderate cytotoxic effect of C3 and C4 complexes has been observed on the development and metabolic activity of HeLa cells, whereas C1 and C2 ligands have a very low effect on them.The synthesized complexes (obtained) inhibit adherence to the inert substrate of bacterial strains S. aureus and P. aeruginosa; therefore, they may be candidates for (potential) therapeutic applications.     

韶关地区部分新建建筑场址土壤氡浓度调查分析

对韶关地区部分新建建筑场址进行土壤氡浓度测量及评价。测量结果表明,韶关地区的土壤氡浓度的总体水平正常,局部地区偏高。     

Phosphorus diffusion and activation in fluorine co-implanted germanium after excimer laser annealing

The diffusion and the activation of phosphorus in phosphorus and fluorine co-implanted Ge after being annealed by excimer laser are investigated. The results prove that the fluorine element plays an important role in suppressing phosphorus diffusion and enhancing phosphorus activation. Moreover, the rapid thermal annealing process is utilized to evaluate and verify the role of fluorine element. During the initial annealing of co-implanted Ge, it is easier to form high bonding energy F_nV_m clusters which can stabilize the excess vacancies, resulting in the reduced vacancy-assisted diffusion of phosphorus. The maximum activation concentration of about 4.4×10²⁰ cm^-3 with a reduced diffusion length and dopant loss is achieved in co-implanted Ge that is annealed at a tailored laser fluence of 175 mJ/cm². The combination of excimer laser annealing and co-implantation technique provides a reference and guideline for high level n-type doping in Ge and is beneficial to its applications in the scaled Ge MOSFET technology and other devices.