Oblique Perforation of Thick Metallic Plates by Rigid Projectiles

Oblique perforation of thick metallic plates by rigid projectiles with various nose shapes is studied in this paper. Two perforation mechanisms, i.e., the hole enlargement for a sharp projectile nose and the plugging formation for a blunt projectile nose, are considered in the proposed analytical model. It is shown that the perforation of a thick plate is dominated by several non-dimensional numbers, i.e., the impact function, the geometry function of projectile, the non-dimensional thickness of target and the impact obliquity. Explicit formulae are obtained to predict the ballistic limit, residual velocity and directional change for the oblique perforation of thick metallic plates. The proposed model is able to predict the critical condition for the occurrence of ricochet. The proposed model is validated by comparing the predictions with other existing models and independent experimental data.The English text was polished by Keren Wang     

观赏植物矮化培养研究

通过试验筛选出适合万寿菊、满天星快速繁殖的培养基．矮壮素可使满天星和万寿菊丛苗数量减少,植株生长明显受抑制,使其节间缩短,叶片增厚,叶色浓绿．矮壮素还有使万寿菊根系发达粗壮,分支较少的作用．500mg／L的矮壮素比较适宜矮化培养,既达到了矮化的效果又不至于阻碍植株正常生长,且试管苗株形紧凑、美观．     

基于Relief算法的特征学习聚类

聚类作为数据挖掘常用工具之一,是按照事物间的相似性进行的一种无监督分类．然而传统的聚类方法较少考虑特征权值．为此,通过研究、分析Relief算法及其在聚类应用中存在的问题,提出了一种基于Relief算法的特征评价函数,并将此函数运用到特征学习聚类中,以解决特征权值取值不当对聚类产生的负面影响．     

Isolation of a carbon nanohoop with M(o)bius topology

Carbon nanohoop,a class of constrained molecular architecture consisting of linked arene units,has attracted considerable interest from both experimental and th...     

基于活动模式的工作者出行生成预测模型

为改进传统出行生成预测以单个出行为分析单元、难以反映个体出行行为的不足,建立了基于活动模式的工作者出行生成预测模型.采用相关性分析和多项logit方法研究了1617个有效样本的居民个体属性、家庭属性、区位属性、出行属性、活动属性所引起的活动和出行生成模式的差异.通过建立包含显著变量的6种典型活动模式效用函数,获得个体选择概率.按概率集计法分析各交通小区各类活动模式总量,结合活动模式中包含的出行链平均长度,进行工作者出行生成量预测.基于活动模式的工作者出行生成预测模型有助于以出行链整体为单元考察多次出行之间的关联性,增强出行生成模型与行为模型的融合.     

Hepatoprotective Activity of Nelumbo nucifera Gaertn. Seedpod Extract Attenuated Acetaminophen-Induced Hepatotoxicity

The aim is to investigate the effect of lotus (Nelumbo nucifera Gaertn.) seedpod extract (LSE) on acetaminophen (APAP)-induced hepatotoxicity. LSE is rich in polyphenols and has potent antioxidant capacity. APAP is a commonly used analgesic, while APAP overdose is the main reason for drug toxicity in the liver. Until now, there has been no in vitro test of LSE in drug-induced hepatotoxicity responses. LSEs were used to evaluate the effect on APAP-induced cytotoxicity, ROS level, apoptotic rate, and molecule mechanisms. The co-treatment of APAP and LSEs elevated the survival rate and decreased intracellular ROS levels on HepG2 cells. LSEs treatment could significantly reduce APAP-induced HepG2 apoptosis assessed by DAPI and Annexin V/PI. The further molecule mechanisms indicated that LSEs decreased Fas/FasL binding and reduced Bax and tBid to restore mitochondrial structure and subsequently suppress downstream apoptosis cascade activation. These declines in COX-2, NF-κB, and iNOS levels were observed in co-treatment APAP and LSEs, which indicated that LSEs could ameliorate APAP-induced inflammation. LSE protected APAP-induced apoptosis by preventing extrinsic, intrinsic, and JNK-mediated pathways. In addition, the restoration of mitochondria and inflammatory suppression in LSEs treatments indicated that LSEs could decrease oxidative stress induced by toxic APAP. Therefore, LSE could be a novel therapeutic option for an antidote against overdose of APAP.     

Characterization of Roasting Time on Sensory Quality,Color, Taste,and Nonvolatile Compounds of Yuan An Yellow Tea

Roasting is crucial for producing Yuan An yellow tea (YAYT) as it substantially affects sensory quality. However, the effect of roasting time on YAYT flavor quality is not clear. To investigate the effect of roasting time on the sensory qualities, chemical components, odor profiles, and metabolic profile of YAYTs produced with 13 min roasting, 16 min roasting, 19 min roasting, 22 min roasting, and 25 min roasting were determined. The YAYTs roasted for 22 min got higher sensory scores and better chemical qualities, such as the content of gallocatechin (GC), gallocatechin gallate (GCG), free amino acids, solutable sugar, meanwhile the lightness decreased, the hue of tea brew color (b) increased, which meant the tea brew got darker and yellower. YAYTs roasted for 22 min also increased the contents of key odorants, such as benzaldehyde, nonanal, β-cyclocitral, linalool, nerol, α-cedrol, β-ionone, limonene, 2-methylfuran, indole, and longiborneol. Moreover, non-targeted metabolomics identified up to 14 differentially expressed metabolites through pair-wise comparisons, such as flavonoids, phenolic acids, sucrose, and critical metabolites, which were the main components corresponding to YAYT roasted for 22 min. In summary, the current results provide scientific guidance for the production of high quality YAYT.     

The Pharmacokinetics in Mice and Cell Uptake of Thymus Immunosuppressive Pentapeptide Using LC-MS/MS Analysis

Thymus immunosuppressive pentapeptide (TIPP) is a novel anti-inflammatory peptide with high efficacy and low toxicity. This study aims to establish a selective LC-MS/MS method for analyzing the analyte TIPP in biological samples, laying the foundation for further PK and PD studies of TIPP. Protein precipitation was conducted in acetonitrile supplemented with 2% formic acid and 25 mg/mL dithiothreitol as a stabilizer, which was followed by backwashing the organic phase using dichloromethane. The chromatographic separation of TIPP was achieved on a C18 column with a gradient elution method. During positive electrospray ionization, TIPP was analyzed via multiple-reaction monitoring. The linear relationships between the concentration of TIPP and peak area in murine plasma cell lysates, supernatants, and the final cell rinse PBS were established within the ranges of 20–5000 ng/mL, 1–200 ng/mL, 10–200 μg/mL, and 0.1–20 ng/mL, respectively (r² > 0.99). Validated according to U.S. FDA guidelines, the proposed method was proved to be acceptable. Such a method had been successfully applied to investigate the pharmacokinetics of TIPP in mice via subcutaneous injection. The plasma half-life in mice was 5.987 ± 1.824 min, suggesting that TIPP is swiftly eliminated in vivo. The amount of TIPP uptake by RBL-2H3 cells was determined using this method, which was also visually verified by confocal. Furthermore, the effective intracellular concentration of TIPP was deduced by comparing the intracellular concentration of TIPP and degrees of inflammation, enlightening further investigation on the intracellular target and mechanism of TIPP.     

Structural Characteristics,Antioxidant and Hypoglycemic Activities of Polysaccharide from Siraitia grosvenorii

The structural characterization, the in vitro antioxidant activity, and the hypoglycemic activity of a polysaccharide (SGP-1-1) isolated from Siraitia grosvenorii (SG) were studied in this paper. SGP-1-1, whose molecular weight is 19.037 kDa, consisted of Gal:Man:Glc in the molar ratio of 1:2.56:4.90. According to the results of methylation analysis, GC–MS, and NMR, HSQC was interpreted as a glucomannan with a backbone composed of 4)-β-D-Glcp-(1→4)-, α-D-Glcp-(1→4)-, and 4)-Manp-(1 residues. α-1,6 linked an α-D-Galp branch, and α-1,6 linked an α-D-Glcp branch. The study indirectly showed that SGP-1-1 has good in vitro hypoglycemic and antioxidant activities and that these activities may be related to the fact that the SGP-1-1’s monosaccharide composition (a higher proportion of Gal and Man) is the glycosidic-bond type (α- and β-glycosidic bonds). SGP-1-1 could be used as a potential antioxidant and hypoglycemic candidate for functional and nutritional food applications.     

Designed Syntheses of Three {Ni6PW9}-Based Polyoxometalates,from Isolated Cluster to Cluster-Organic Helical Chain

Three new hexa-Ni-substituted Keggin-type polyoxometalates (POMs), [Ni₆(OH)₃- (DACH)₃(H₂O)₆(PW₉O₃₄)]·31H₂O (1), [Ni(DACH)₂][Ni₆(OH)₃(DACH)₃(HMIP)₂(H₂O)₂(PW₉O₃₄)]·56 H₂O (2), and [Ni(DACH)₂][Ni₆(OH)₃(DACH)₂(AP)(H₂O)₅(PW₉O₃₄)]·2H₂O (3) (DACH = 1,2-Diami- nocyclohexane, MIP = 5-Methylisophthalate, AP = Adipate) were successfully made in the presence of DACH under hydrothermal conditions. 1 is an isolated hexa-Ni-substituted Keggin unit decorated by DACH. In order to further construct POM cluster-organic frameworks (POMCOFs) on the basis of 1, by analyzing the steric hindrances and orientations of the POM units, the rigid HMIP and flexible AP ligands were successively incorporated, and another anionic monomeric POM 2 and the new 1D POM cluster organic chain (POMCOC) 3 were obtained. HMIP ligand still acts as a decorating group on the Ni₆ core of 2 but results in the different spatial arrangement of the {Ni₆PW₉} units. AP ligands in 3 successfully bridge adjacent isolated POM cluster units to 1D POMCOC with left-hand helices. The AP in 3 is the longest aliphatic carboxylic acid ligand in POMs, and the 1D POM cluster-AP helical chain represents the first 1D POMCOC with a helical feature.