血小板源性生长因子/蛋白激酶B通路在压力超负荷诱导的心室重构中的作用及机制研究

目的:分析血小板源性生长因子（PDGF）/蛋白激酶B（AKT）通路在压力超负荷诱导的心室重构中的作用及机制。方法:选取C57BL/6雌性小鼠55只，建立主动脉弓缩窄模型，成功建模45只，小鼠随机数字表法分为假手术组、DMSO组和实验组，假手术组小鼠开胸后逐层缝合，不进行主动脉缩窄术（TAC），开胸24 h后给予PBS溶液200 μL加DMSO 50 μL，DMSO组TAC术后24 h给予PBS溶液200 μL加DMSO 50 μL，实验组TAC术后24 h给予PBS溶液200 μL加抑制剂AG1296 50 μL，观察小鼠心功能及心肌组织病理形态。慢病毒感染建立PDGF基因不同表达人脐静脉内皮细胞（HUVEC）细胞鉴定和培养，依据细胞不同处理方式分为对照组、PDGF组、shRNA组和PDGF+IMA组，检测p-AKT及t-AKT蛋白在HUVEC细胞内表达情况。结果:DMSO组小鼠左室收缩末期容积（LVESV）、左室舒张末期容积（LVEDV）、左室收缩末期内径（LVESD）及左室舒张末期内径（LVEDD）较假手术组升高，左室射血分数（EF）、左室短轴缩短率（FS）较假手术组降低。实验组LVESV、LVEDV、LVESD及LVEDD较DMSO组降低，EF、FS较DMSO组升高，差异有统计学意义（P＜0.05）。假手术组小鼠心肌组织整齐排列，间隙正常；DMSO组小鼠形态不规整，炎性细胞浸润，细胞间隙变大，胞核深染。实验组小鼠膨大或坏死细胞减少，间隙变小，炎性浸润降低。DMSO组小鼠心肌细胞横截面积较假手术组升高，实验组小鼠心肌细胞横截面积较DMSO组降低，差异有统计学意义（P＜0.05）。PDGF+IMA组细胞内p-AKT及t-AKT蛋白表达较PDGF组及shRNA组显著降低，差异有统计学意义（P＜0.05）。结论:PDGF可加速压力超负荷诱导心室重构，促进形成心肌组织纤维化，而抑制PDGF/AKT通路可改善心肌细胞肥大。     

What is a crystal to the new chemical crystallographer,after that first,automated structure analysis?

This educational review postulates the importance of maintaining an adequate level of crystallographic education among structure-dependent scientists whose interests are not primarily in crystallography, at a time when automation and validation have made it possible to obtain high-quality structure analyses in many cases with a minimum of crystallographic background. The topics addressed are intended to form a second round of crystallographic education for a novice user whose first round involved hands-on experience with structure solution and an introduction to elementary concepts. The specific topics, chosen for their relevance as basic knowledge and their lack of emphasis in many formal treatments, are (1) crystallographic reference frames and the utility of the reciprocal cell in geometrical calculations; (2) the relationship between the two concepts that constitute our model of the crystal, namely the unit cell and the lattice; (3) the manner in which an atom is represented in concept and in practice; (4) the importance of interleaved symmetry elements required by the presence of additional symmetry on a lattice; (5) the harnessing of the natural properties of the crystalline state for the potential manipulation of properties of synthetic crystals; and (6) useful terminology for navigating a crystal structure.     

我国MTBE的生产使用现状及趋势分析

对我国MTBE的生产工艺及下游产品进行了详细的分析,重点分析了影响MTBE产品生产使用的各方面因素,从能源方针、车用燃料政策及环保要求等角度对我国MTBE产品的未来发展趋势进行了预测分析。结果显示,2020年以后我国汽油调和用MTBE的生产使用量将逐步降低,但此过程可能会较为平缓。     

Assessing trophic position quantification methods for three piscivorous freshwater fish using stable isotopes and stomach contents

Accurate trophic position (TP) estimates are important for the development of ecosystem-based management plans. TPs can be quantified by carbon (δ¹³C) and nitrogen (δ¹⁵N) stable isotopes in tissues, but these can disagree with observed and perceived feeding ecology. A recent method that has used a scaled diet-tissue discrimination factor (DTDF), reflecting the inverse relationship between DTDF and δ¹⁵N, was found to better describe TPs of predatory fish species in marine ecosystems, but this has not been tested in freshwater ecosystems. Here, we compare methods of TP estimations in the Lake Huron-Erie corridor (HEC), a system where high diversity of prey items has contributed to the concern that foraging ecology of piscivorous fish species is poorly understood. Using δ¹⁵N and δ¹³C, we quantified TP of longnose gar (Lepisosteus osseus), largemouth bass (Micropterus salmoides), and northern pike (Esox lucius) to assess the efficacy of a scaled DTDF compared to traditional DTDF isotope methods and stomach content analysis (SCA). The scaled DTDF method produced TP estimates that were at times consistent with SCA and were generally higher and with a greater range among individuals than non-scaled DTDFs. The scaled method was not sensitive to baseline choice nor influenced by incorporating carbon source in the model. Greater variability of TP estimates using a scaled DTDF suggests more complex trophic structuring in the upper trophic level guild of the HEC. These results, particularly the lack of baseline sensitivity, provide support for using the scaled DTDF in freshwater food web characterization.     

Cell Sheet Comprised of Mesenchymal Stromal Cells Overexpressing Stem Cell Factor Promotes Epicardium Activation and Heart Function Improvement in a Rat Model of Myocardium Infarction

Cell therapy of the post-infarcted myocardium is still far from clinical use. Poor survival of transplanted cells, insufficient regeneration, and replacement of the damaged tissue limit the potential of currently available cell-based techniques. In this study, we generated a multilayered construct from adipose-derived mesenchymal stromal cells (MSCs) modified to secrete stem cell factor, SCF. In a rat model of myocardium infarction, we show that transplantation of SCF producing cell sheet induced activation of the epicardium and promoted the accumulation of c-kit positive cells in ischemic muscle. Morphometry showed the reduction of infarct size (16%) and a left ventricle expansion index (0.12) in the treatment group compared to controls (24–28%; 0.17–0.32). The ratio of viable myocardium was more than 1.5-fold higher, reaching 49% compared to the control (28%) or unmodified cell sheet group (30%). Finally, by day 30 after myocardium infarction, SCF-producing cell sheet transplantation increased left ventricle ejection fraction from 37% in the control sham-operated group to 53%. Our results suggest that, combining the genetic modification of MSCs and their assembly into a multilayered construct, we can provide prolonged pleiotropic effects to the damaged heart, induce endogenous regenerative processes, and improve cardiac function.     

Pore structure of reactively synthesized nanolaminate Ti3SiC2 alloyed with Al

Ti₃SiC₂ has the unique properties integrating the advantages of metals and ceramics, and good open pore structure when alloyed with Al. In this work, porous Ti₃SiC₂ compounds with different Al/Si atom ratios were prepared through the reactive synthesis of elemental powders at 1300 °C. The results indicate that the phase compositions are determined by Al element mole number, and that the pore structure can be controlled through varying Ti particle size. The MAX phase transits from Ti₃SiC₂ with Al element mole number no more than 0.6 to Ti₃AlC₂ with Al element mole number in the range of 0.8–1.2. When Al element mole number is 0.6, the porous compound has a single MAX phase of Ti₃SiC₂ with uniform microporous structure and high bending strength. Porous Ti₃SiC₂ alloyed with 0.6Al has a slow linear increase rate of 0.0083%/μm in open porosity with increasing Ti particle size, and a strict linear relationship between the maximum aperture and Ti particle size with the increase rate of 0.0342 μm/μm. The pore structure formed by the phase transition mechanism for porous MAX phase has the smallest tortuosity factor compared with that formed by the clearance mechanism and the Kirkendall effect.     

荷花山铅锌矿与铜陵地区其它矿床成矿控制因素的对比研究

为了探讨荷花山铅锌矿控矿因素上与铜陵地区其它矿床异同，运用宏、微观相结合，地质观察研究同位素地球化学以及流体包裹体分析相结合的方法，通过地层岩性、地质构造、特定地质体及成矿流体的来源和性质等几个方面与成矿关系的比较，揭示了这种新类型矿床的控矿因素的特点是与岩浆关系不密切的低温热液、角砾岩控矿。得出了这种新类型矿床既具有铜陵地区其它矿床的控矿因素，同时也具有自己独特的控矿因素的结论。     

红石岩煤矿隐蔽致灾因素分析

为保障煤矿安全开采,有针对性地制定预防和治理措施,对红石岩煤矿隐蔽致灾因素进行探究。首先梳理了红石岩煤矿已揭露的地质情况和现有的钻探、物探和水质化验成果,瓦斯鉴定等资料,结合煤矿隐蔽致灾因素具有隐蔽性、时变性、突发性、难探测和难预防的特点,对其地面和井田内的采空区、废弃老窑,钻孔、地质构造、地下含水体、瓦斯和煤层自燃及煤层顶底板等因素进行了分析。总结出该矿主副井筒周边采空区水、因采动影响产生的顶底板导水裂隙带等主要隐蔽致灾因素,以及断层的活化和滞后出水及带出的有害气体等次要隐蔽致灾因素,并提出了相应的预防和治理措施。     

Synthesizing a uniformly spaced array pattern using integral operator for removing progressive phase shift

In this article, an analytical technique is introduced to obtain the excitation coefficients of uniformly spaced linear antenna arrays in order to achieve a desired array factor. By integration of the prescribed array factor, the array factor dependency to the progressive phase shift is eliminated. A new system of linear equations is consequently obtained whose solution represents the excitation coefficients of the array. Some examples are presented to verify the accuracy of the introduced method. The performance of this strategy is compared with those obtained by the other well‐known techniques such as Woodward‐Lawson and Fourier transform. It is shown that the presented method estimates the desired array pattern with a very good precision.