Low-amplitude vector screening solitons

We show self-coupled and cross-coupled vector beam evolution equations in the low-amplitude regime for screening solitons, which can exhibit the analytical solutions of bright-bright and dark-dark vector solitons. Our analysis indicates that these self-coupled vector solitons are obtained irrespective of the intensities of the two optical beams, whereas these cross-coupled vector solitons can be established when the intensities of the two optical beams are equal. Relevant examples are provided where the photorefractive crystal is lithium niobate (LiNbO3). The stability properties of these vector solitons have been investigated numerically and it has been found that they are stable.     

Self-deflection of bright soliton in a separate bright-dark screening soliton pair based on higher-order space charge field

Based on the interaction of the separate soliton pair, the self-deflection of the bright screening soliton in a bright-dark pair is studied by taking the higher order space charge field into account. Both numerical and analytical methods are adopted to obtain the result that the higher order of space charge field can enhance the deflection process of the bright soliton and varying the peak intensity of the dark soliton can influence the self-deflection strongly. The expression of the deflection distance with the dark soliton's peak intensity is derived, and some corresponding properties of the self-deflection process are figured out.     

LC-MS法测定大鼠血浆中的冬凌草甲素含量

建立大鼠血浆中冬凌草甲素的LC-MS测定方法.用C18柱（150mm×2.0mm,5μm）色谱柱,乙腈-水（V/V=50∶50）为流动相,乙酸乙酯作为萃取剂,HPLC/电喷雾离子源质谱检测（HPLC/ESI-MS）.该方法测定乙酸乙酯萃取的冬凌草甲素在0.018-9.2μg·mL^-1浓度范围内线性关系良好（R2=0.9992）.定量下限为0.018μg·mL^-1,提取回收率和RSD分别为100.56％-101.74％和8.88％.采用LC-MS法检测乙酸乙酯萃取的大鼠血浆中的冬凌草甲素,可为进一步深入研究冬凌草甲素在人体内药代动力学特征提供可靠检测手段.     

美罗培南有关物质的LC-MS分析

建立了HPLC梯度冼脱方法和质谱条件,对美罗培南水溶液的降解产物进行定性分析,推测出降解产物的化学结构式和降解途径。结果表明,美罗培南水溶液主要产生4个杂质峰,杂质Ⅰ在美罗培南主峰之前出峰,是美罗培南的开环降解物,杂质Ⅱ、Ⅲ和Ⅳ在美罗培南主峰之后出峰,是美罗培南的二聚体。中国药典的等度洗脱方法仅能检出前三个杂质峰,不能检出杂质Ⅳ。本文为进一步完善美罗培南的质量标准和提高临床用药的安全性提供依据。     

Strongly screening β~- decay antineutrino energy loss in presupernova

In this study, we investigate the ion-ball screening model(model(I)), focused on the screening electrostatic potential per electron under the Wigner-Seitz approximation and the Q-value correction. By considering the changes of the Coulomb free energy and the effects of strong electron screening(SES) on the Q-value and the Coulomb chemical potential, we discuss the linear-response screening model(model(Ⅱ)). We also analyze the influence of the SES on the β~- decay antineutrino energy loss rate by considering the corrections of the Q-value, the electron chemical potential, and electron energy, as well as the shell and pair effects. The antineutrino energy loss rate is found to increase by two orders of magnitude(e.g., the SES enhancement factor reaches 651.9 for model(Ⅱ)) due to the SES effect.     

Electron screening corrections to 0+→0+ beta decays

We correct the perturbative calculation of the electron screening corrections to 0⁺→0⁺ beta decays given by Drukarev and Strikman. The corrected calculation agrees with the standard Rose treatment of the screening corrections and eliminates the Z-dependent discrepancies in the corrected ft values for the superallowed Fermi transitions claimed by those authors.     

人血浆中氯雷他定浓度的LC-MS测定

建立了LC-MS法测定人血浆中氯雷他定浓度的方法。血浆在碱性条件下用乙醚-二氯甲烷(2.5∶1,V/V)提取,以罗哌卡因为内标,采用ZORBAX Eclipse XDB-C8柱,API-ES质谱检测器,正离子模式,采集方式为SIM。流动相为乙腈-水(0.2%NH4Ac,0.1%HAc)。氯雷他定在0.2—50ng/mL范围内线性关系良好,相对回收率为88.0%—98.6%,RSD小于10%,定量下限为0.2ng/mL。     

Color screening,absorption, and σ tot pp at LHC

We show that a growth of the proton-proton total cross section with energy can be entirely attributed to the purely perturbative mechanism. The infrared regularization at rather short distances R _c ? 0.3 fm allows extending the BFKL technique from deep inelastic to hadron-hadron scattering. With the inclusion of the absorption corrections our results are in agreement with the LHC data on σ _tot ^pp .     

TheJ/Ψ absorption cross section in nuclei and color screening

Data on 120 GeV photoproduction ofJ/'s in nuclear targets are re-examined to extract the absorption cross section forJ/'s in high energy collisions with nucleons. We find _a =6.6±2.2 mb in contrast with an earlier estimate of 1–2 mb. Comparison of low and high energy data on photon producedJ/'s thus no longer show possible evidence for observable effects of color screening. Examination of representative data on the Feynmanx distributions ofJ/ production by hadrons demonstrates how to extract both the total inelasticJ/-nucleon cross section and the partial cross section into open charm. We find that the data is inconsistent with any significant contribution from color screening.     

The “screening phase transitions” in the two-dimensional Coulomb gas

The Mayer series of a Coulomb gas with fixed ultraviolet cutoff is studied in two dimensions. In particular, we show the existence of infinitely many thresholdsT _n =(e ²/8k)(1-1/2n)^–1 k=Boltzmann's constant,e=electric charge,n=1, 2,..., which are conjectured to reflect a sequence of transitions from pure multipole phase (the Kosterlitz-Thouless region) to a plasma phase (the Debye screening region) via an infinite number of intermediate phases. Mathematically we prove that the Mayer series' coefficients of order up to 2n are finite if the temperatureT is <T _n. ForT<T all the coefficients are finite and the gas can be formally interpreted as a multipole gas with multipoles with finite activity.The first author was supported in part by NSF grant No. MCS-8108814 (A03).     

a绝对=a相对＋a牵连在动力学中的运用

凡惯性定律成立的参照系，叫做惯性系；惯性定律不成立的参照系，叫做非惯性系．牛顿第一定律和第二定律在非惯性系中是不适用的．因此，在研究动力学问题时通常应选择惯性系做为参照系．为了在非惯性系中仍能应用牛顿运动定律，往往需引入惯性力的概念．但如果不是使用惯性力的概念，而是同时考虑非惯性系的变速运动以及质点相对非惯性系的相对运动，则在惯性系中使用牛顿运动定律依然方便．     

Ionic liquids screening for desulfurization of natural gasoline by liquid–liquid extraction

Seventy five ionic liquids (ILs) were tested as a sequestering agent of sulfured compounds in natural gasoline (NG). Desulphurization of NG was performed by means of liquid–liquid extraction method at room temperature and atmospheric pressure. Experimental ILs containing imidazolium, pyridinium, and ammonium cations along with organic and inorganic anions were synthesized conventionally and under microwave and sonochemical conditions. The effect of the molecular structure of ILs on the desulfurization efficiency of NG with high sulfur content was evaluated. Analysis indicated that the anion type played a more important role than the cation on the desulphurization process. ILs based on halogen–ferrates and halogen–aluminates exhibited the highest efficiency in sulfur removal, and their efficiency is further improved when there is an excess of metallic salt in a ratio of at least 1:1.3 during the synthesis of the corresponding IL. An explanation for the ability of metallic ILs to remove sulfur-containing compounds from natural gasoline based on the ratio of the ionic charge to the atomic radius is proposed. Furthermore, a method to recover and reuse water-sensitive to halogenated precursors is described.     

Radiation Rate of a Two-Level Atom in a Spacetime with a Reflecting Boundary

We study a two-level atom in interaction with a real massless scalar quantum field in a spacetime with a reflecting boundary. We calculate the rate of change of the atomic energy for the atom. The presence of the boundary modifies the quantum fluctuations of the scalar field, which in turn modifies the rate of change of the atomic energy. It is found that the modifications induced by the presence of a boundary make the spontaneous radiation rate of an excited atom to oscillate near the boundary and this oscillatory behaviour may offer a possible opportunity for experimental tests for geometrical （boundary） effects in flat spacetime.     

Role of Gribov’s inelastic screening in the nucleus-nucleus interactions at high energies

It is found that the inclusion of Gribov’s inelastic screening within the quasieikonal approach generalized to the case of nucleus-nucleus interactions leads to a significant decrease (～18%) in the number of “wounded” nucleons and in the multiplicity of intranuclear collisions in central interactions between nuclei. This can significantly affect experimental estimates of the degree of “quenching” of jets and hydrodynamic calculations of the behavior of the quark-gluon plasma appearing in the indicated interactions.     

Random Motion of a Charged Test Particle with a Constant Classical Velocity in a Spacetime with a Plane Boundary

We study the random motion of a charged test particle coupled to electromagnetic vacuum fluctuations near a perfectly reflecting plane boundary with a nonzero classical constant velocity in a direction parallel to the plane. We calculate the mean squared fluctuations in the velocity and position of the test particle taking into account both fluctuating electric and magnetic forces. Our results show that the influence of fluctuating magnetic fields is, in general, of the higher order than that caused by fluctuating electric fields and is thus negligible.     

Biaryl scaffold-focused virtual screening for anti-aggregatory and neuroprotective effects in Alzheimer’s disease

Background

Alzheimer’s disease (AD) is a primary cause of dementia in ageing population affecting more than 35 million people around the globe. It is a chronic neurodegenerative disease caused by defected folding and aggregation of amyloid beta (Aβ) protein. Aβ is formed by the cleavage of membrane embedded amyloid precursor protein (APP) by using enzyme ‘transmembrane aspartyl protease, β-secretase’. Inhibition of β-secretase is a viable strategy to prevent neurotoxicity in AD. Another strategy in the treatment of AD is inhibition of acetylcholinesterase. This inhibition reduces the degradation of acetylcholine and temporarily restores the cholinergic function of neurons and improves cognitive function. Monoamine oxidase and higher glutamate levels are also found to be linked with Aβ peptide related oxidative stress. Oxidative stress leads to reduced activity of glutamate synthase resulting in significantly higher level of glutamate in brain. The aim of this study is to perform in silico screening of a virtual library of biaryl scaffold containing compounds potentially used for the treatment of AD. Screening was done against the primary targets of AD therapeutics, acetylcholinesterase, β-secretase (BACE1), Monoamine oxidases (MAO) and N-Methyl-D-aspartate (NMDA) receptor. Compounds were screened for their inhibitory potential by employing molecular docking approach using AutoDock vina. Binding energy scores were embodied in the heatmap to display varies strengths of interactions of the ligands targeting AD.

Results

Several ligands showed notable interaction with at least two targets, but the strong interaction with all the targets is shown by very few ligands. The pharmacokinetics of the interacting ligands was also predicted. The interacting ligands have good drug-likeness and brain availability essential for drugs with intracranial targets.

Conclusion

These results suggest that biaryl scaffold may be pliable to drug development for neuroprotection in AD and that the synthesis of further analogues to optimize these properties should be considered.

     

Electron screening in the 7Be + p → 8B + γ reaction

We evaluate the effect of screening by bound electrons in the ⁷Be(p,γ)⁸B reaction, where the ⁷Be target contains bound electrons, in the framework of the adiabatic representation of the three-particle problem. A comparison with two other approximations (united atom and folding) is presented. A good agreement between the “united atom” approximation and the exact solution is found. We also discuss the screening corrections induced by two K-shell electrons on a ⁷Be target. The consequences of bound electron screening for ⁷Be and ⁸B solar neutrino fluxes are discussed.