Investigate oxoazolidine-2,4-dione based eutectic mixture via DFT calculations and SAR

In this work, DFT calculations for the designed eutectic mixtures (EMs) using oxoazolidine 2,4-dione (OZD) and zinc chloride (ZnCl2) are done. The interaction between the hydrogen bond donor and hydrogen bond acceptor at atomic level to get EMs are studied using DFT calculations. At room temperature, the stability of these various systems have been investigated using thermodynamic values or parameters such as enthalpy, free energy and others. DFT calculations is used to investigate the possibility of forming the systems (EMs). Further, the impact of varying the temperature on each system was also investigated (323K, 348K). Various other thermodynamic parameters are studied like dipole moment, hardness, chemical potential of the systems (individual molecules and EMs) at different temperatures. The results of the calculations showed that O1Z4 and O4Z1 have maximum dipole moment having values 8.1291, 9.8801 respectively, indicating maximum polarizability. Change in free energy for O1Z4 is least and was found to be ?37.2496 kcal/ mol. Further on changing the temperature, the parameters do not show much variation. Additionally, we have analyzed structure activity relationship (SAR) method to understand the physico-chemical properties of designed EMs and predict their regression and correlation to optimized energy. From the calculated values of pOE model, the value of r² is 0.9995 confirms the validity of the equation obtained. The results of this study suggest a link between the structures that have been utilized to describe the intermolecular interaction between the hydrogen bond donor and acceptor, as well as the stability of the EMs.     

A structure-activity relationship study of compounds with antihistamine activity

A structure-activity relationship (SAR) analysis of H(1)-, H(2)- and H(3)-antihistamine activity was carried out and chromatographic data of 2-[2-(phenylamino)thiazol-4-yl]ethanamine, 2-(2-benzyl-4-thiazolyl)ethanamine, 2-(2-benzhydrylthiazol4-yl)ethanamine, 2-(1-piperazinyl- and 2-(hexahydro-1H-1,4-diazepin-1-yl)benzothiazole, 2-(1-piperazinyl)benzothiazole, 2-[4-(1-alkyl)piperidinyl]benzothiazole, 2-(N,N',N'-dimethylalkyl-1,2-ethanediamino)benzothiazole, 2[1-(4-aminopiperidinyl)]benzothiazole, 2-[2-phenyl-4-thiazolyl]ethanamine derivatives and selected H(1)- and H(2)-antihistamine drugs were obtained. NP TLC and RP2 TLC plates (silica gel NP 60F(254) and silica gel RP2 60F(254) silanized precoated), impregnated with a solution of aspartic acid (L-Asp) and a solution of an analogue of aspartic acid (propionic acid), were used in two developing solvents as H(1)-, H(2)- and H(3)-antihistaminic interaction models. The lipophilicity data of the examined compounds were obtained and used in the SAR assay. Biochromatographic tests using TLC plates impregnated with solutions of asparic acid or propionic acid were found to be a source of useful data for the qualitative analysis of compounds with different structures, demonstrating activity to histamine H(1)-, H(2)- and H(3)-receptors. The four presented discriminant models based on biochromatographic studies are an efficient tool in the SAR analysis for initial prediction of compound activity direction within histamine receptors.     

A structure-activity relationship study of brusatol, an antitumor quassinoid

Analogues of brusatol (2) were prepared and examined for their cytotoxic activity by using P-388 murine leukemia cells. The following structure-activity relationships were noted: (i) an enone carbonyl oxygen or an enolic oxygen at C-2 is essential, but an oxygen at C-3 not essential for the activity; (ii) the C-11 β-hydroxyl group is important for the activity; and (iii) the length of the ester alkoxy side chain at C-21 seems to have a slight effect on the activity.     

Synthesis of melampolides and cis,cis-germacranolides as natural herbicide models

The comparative study between the theoretical molecular properties of the starting materials and the yields in the transformation of melampolides to cis,cis-germacranolides using SeO₂/t-BuOOH (TBHP) as oxidant allows to establish a feasible relationship with their values of dipolar moment. Conditions for this transformation are optimized and some mechanistic considerations are made based in this finding. Cluster analysis of the phytotoxic activity of the melampolides and cis,cis-germacranolides obtained shows that the activity is greatly influenced by the spatial shape of the backbone, prevailing upon other factors such as the presence of reactive functional groups.     

Corrective measures in turbulent pipe flows and extended self-similarity

Significant statistical bias in LDA measurements and how to adequately deal with it is a subtle problem when dealing with turbulent flows. In order to attempt a clarification we have performed measurements on a non-standard “grid experiment” where a clear bias effect is found. We have investigated the effect of several corrective measures and find that best results, in the sense of having the first moment converge to zero, are obtained when using the time between events as statistical weights. The corrected time series have been used to check for extended self-similarity (ESS). Even though no scaling regime is seen for the third moment and the flow certainly is neither isotropic nor homogeneous, perfect ESS scaling based on the absolute third moment is observed up to the twelfth moment, extending into a time domain regime where the Taylor hypothesis of frozen turbulence is obviously violated. Reversing the argument this indicates that the correction scheme needed can be experimentally decided on using the criterion stated above and especially so if ESS is to be expected. Finally we have used the corrected data to quantify the deviations from Gaussian behavior of the velocity difference probability density function for a weakly turbulent flow. Through comparison with results on the Gaussian-Lorentzian distribution we find that the even part of the experimental distribution can be reproduced quite well by a single-parameter family of distributions with second moment equal unity. Received 5 August 1998 and Received in final form 21 December 1998     

发现生物大分子高亲和性配体的新方法——SAR-by-NMR

由于许多药物通过和生物体内的大分子(如蛋白质和核酸) 的选择性结合发挥效用, 因此快速、有效地发现靶分子的高亲和性配体成为各种药物发现方法的首要目标。在现代生物技术和NMR 技术高度发展的基础上产生的一种发现生物大分子高亲和性配体的新方法--SAR-by-NMR, 由于采用NMR 技术可以综合多种药物设计方法的优势, 能够在短时间内得到先导化合物, 从而大大加快了药物发现的速度并能节省大量的费用。本文介绍了SAR-by-NMR 发现高亲和性配体的基本原理、特点及其在药物发现中的应用。     

用于SAR估计的基于U-Net网络的快速膝关节模型重建

膝关节高场磁共振成像（MRI）时,射频功率沉积（SAR）是一个关键的安全指标.目前对于局部SAR的准确估计只能通过电磁仿真实现,这就要求得到每一个个体的膝关节模型.本文提出一种针对低场磁共振图像的基于卷积神经网络的分割方法,以实现膝关节磁共振图像的快速重建.数据集来自于矢位T₁加权自旋回波图像,将膝关节组织按照"肌肉-脂肪-骨骼"模型进行简化,除脂肪与骨骼之外的其他组织归类为肌肉.采用一种全卷积的神经网络,即U-Net进行逐层的图像分割,卷积层数为4,训练采用交叉熵函数.本文对图像的自动分割结果与手动标注结果进行了定量的比较.此外,采用3 T正交鸟笼线圈进行了SAR仿真,结果验证了组织简化对于SAR估计的可行性,并且所提方法构建的模型可以得到较为精准的局部SAR分布.     

Synthesis and Investigation of Flavanone Derivatives as Potential New Anti-Inflammatory Agents

Flavonoids are polyphenols with broad known pharmacological properties. A series of 2,3-dihydroflavanone derivatives were thus synthesized and investigated for their anti-inflammatory activities. The target flavanones were prepared through cyclization of 2′-hydroxychalcone derivatives, the later obtained by Claisen–Schmidt condensation. Since nitric oxide (NO) represents an important inflammatory mediator, the effects of various flavanones on the NO production in the LPS-induced RAW 264.7 macrophage were assessed in vitro using the Griess test. The most active compounds were flavanone (4G), 2′-carboxy-5,7-dimethoxy-flavanone (4F), 4′-bromo-5,7-dimethoxy-flavanone (4D), and 2′-carboxyflavanone (4J), with IC50 values of 0.603, 0.906, 1.030, and 1.830 µg/mL, respectively. In comparison, pinocembrin achieved an IC₅₀ value of 203.60 µg/mL. Thus, the derivatives synthesized in this work had a higher NO inhibition capacity compared to pinocembrin, demonstrating the importance of pharmacomodulation to improve the biological potential of natural molecules. SARs suggested that the use of a carboxyl-group in the meta-position of the B-ring increases biological activity, whereas compounds carrying halogen substituents in the para-position were less active. The addition of methoxy-groups in the meta-position of the A-ring somewhat decreased the activity. This study successfully identified new bioactive flavanones as promising candidates for the development of new anti-inflammatory agents.     

基于InSAR的西安地面沉降与地裂缝发育特征研究

哺乳动物细胞胞质分裂过程中伴随着一系列形态学改变,随着分裂沟不断收缩,形成连接两 个子细胞的细胞间桥. 间桥不断拉长、变细,直至断裂、生成两个子细胞. 采用细胞力学 和形态学测量及分析方法,通过施加肌球蛋白II抑制剂,定量研究了NRK细胞间桥变细动力 学; 采用细胞免疫荧光技术, 检测了早期胞质分裂肌动蛋白的分布,揭示肌球蛋白II缺失细 胞胞质分裂可能的机制. 结果表明：施加肌球蛋白II抑制剂的NRK细胞, 其整体形态学和细胞 间桥形态学曲线明显不同于0.3%DMSO组. 根据流体力学特性和所测量的力学参数对曲线 进行模拟发现,表面张力对肌球蛋白II抑制组细胞的间桥动力学曲线轨迹影响很大. 研究结 果提示由细胞力学特性决定的拉普拉斯压力和细胞运动共同参与了肌球蛋白II缺失细胞胞 质分裂的调节.     

4G antennas for wireless eyewear devices and related SAR

In this paper, we first present a feasibility study to design 4G antennas (700–960 MHz and 1.7–2.7 GHz) for eyewear devices. Those eyewear devices should be connected to the last generation cellular networks, Wireless Local Area Networks or wireless hotspots. Three coupling element type antennas with their matching networks are evaluated in terms of reflection coefficient and total radiation efficiency when the eyewear is placed on the user's head. We also present Specific Absorption Rate (SAR) simulations when the eyewear is positioned over a homogeneous SAM phantom and over a heterogeneous VH (Visible Human) phantom: the SAR levels are compared to international limit values. In a second step, we present experimental results obtained with 3D printed eyewear and coupling elements etched on a classical PCB substrate where the matching circuits are optimized close to the feeding point of the coupling element. Simulated and measured values are in very good agreement: 7 to 16% and 9 to 35% total efficiency are respectively obtained for the low- and high-frequency bands. However, simulated SAR values are somewhat higher than authorized levels with preoccupant high electromagnetic field distribution close to the eye of the user.