书籍评论──Modern History: the Rise of a Democratic, Scientific, and Industrialized Civilization

教科书一类的书籍,常被学者轻视,以为只是便利初学,说到学术贡献,那就简陋不足“登大雅之堂”。不过偶有杰出的作品,不能因为他是教科书,便一概抹煞。如此刻所举的Becker教授的近代史,虽只是一本教科书,却是其中一个妙品。 Becker先生在美国康奈尔大学(Corned Universits)任历史教授有年,作过美国历史学会的会长、是位史学界很负盛名的作者。我会上过他的课,听过他的演讲。听讲时并不觉得他的神奇,一副攻苦憔悴的面容,一种缓声静气的讲说,同别位教授似乎没甚差别。但是看到他的作品,(1)印象就大不然了。一开卷就觉得他的下笔不同凡众:见解…     

地表受光面和阴影温差的潜在信息及遥感土壤水分的新途径

在可见光和近红外遥感中，地物阴影通常认为是提取信息的噪声或干扰．而 在热红外遥感中，发现地物光照面和阴影的信息差是提取热量平衡参数的重要信息源． 通过实践，建立了以地物光照面和阴影的表面温度差为基础的土壤水分含量的遥感模 型，为利用多角度信息提取遥感土壤水分开辟了新的途径．在中国科学院禹城综合试 验站遥感试验场开展了模型论证试验．试验资料很好地支持了模型的验证．所用方法 与现有的热惯量方法和作物缺水指数方法进行了对比，分析了本方法的优越性和局限 性．     

HDAC2 and TXNL1 distinguish aneuploid from diploid colorectal cancers

DNA aneuploidy has been identified as a prognostic factor for epithelial malignancies. Further understanding of the translation of DNA aneuploidy into protein expression will help to define novel biomarkers to improve therapies and prognosis. DNA ploidy was assessed by image cytometry. Comparison of gel-electrophoresis-based protein expression patterns of three diploid and four aneuploid colorectal cancer cell lines detected 64 ploidy-associated proteins. Proteins were identified by mass spectrometry and subjected to Ingenuity Pathway Analysis resulting in two overlapping high-ranked networks maintaining Cellular Assembly and Organization, Cell Cycle, and Cellular Growth and Proliferation. CAPZA1, TXNL1, and HDAC2 were significantly validated by Western blotting in cell lines and the latter two showed expression differences also in clinical samples using a tissue microarray of normal mucosa (n?=?19), diploid (n?=?31), and aneuploid (n?=?47) carcinomas. The results suggest that distinct protein expression patterns, affecting TXNL1 and HDAC2, distinguish aneuploid with poor prognosis from diploid colorectal cancers.     

短纤维混杂增强铝基复合材料的性能及其最佳纤维体积分数的选择

通过对用挤压铸造制备的含不同体积分数的Ａｌ２Ｏ３短纤维和碳纤维混杂增强的铝基复合材料进行抗拉强度、摩擦、磨损性能的研究，综合分析、比较之后认为，从这３种性能来看，纤维的体积分数有一个最佳值范围，且 （Ａｌ２Ｏ３ｆ）＝７％及　（Ｃｆ）＝６０％的复合材料性能最佳．这是以后制备该复合材料最佳纤维体积分数的选择依据之一．     

层合复合材料的自由角效应--三维有限差分解

针对层合复合材料的自由角附近的层间高应力问题,提出了一个三维有限差分法的方案,计算层合复合材料在变温下的自由角效应问题,同时与以前的解进行了比较.研究表明,所提出的有限差分方案所得的解是稳定的、收敛的,对[90°/0°]s对称铺层碳纤维增强塑料和Ni/Al层合复合材料算例来说,比以前的半解析解更接近于用三维有限元计算的结果.还讨论了层间应力的应力场和层间破坏之间的关系,发现层间剥离应力,即正应力可能是层间破坏的主要因素.     

Structural basis of highly conserved ribosome recycling in eukaryotes and archaea

Ribosome-driven protein biosynthesis is comprised of four phases: initiation, elongation, termination and recycling. In bacteria, ribosome recycling requires ribosome recycling factor and elongation factor G, and several structures of bacterial recycling complexes have been determined. In the eukaryotic and archaeal kingdoms, however, recycling involves the ABC-type ATPase ABCE1 and little is known about its structural basis. Here we present cryo-electron microscopy reconstructions of eukaryotic and archaeal ribosome recycling complexes containing ABCE1 and the termination factor paralogue Pelota. These structures reveal the overall binding mode of ABCE1 to be similar to canonical translation factors. Moreover, the iron-sulphur cluster domain of ABCE1 interacts with and stabilizes Pelota in a conformation that reaches towards the peptidyl transferase centre, thus explaining how ABCE1 may stimulate peptide-release activity of canonical termination factors. Using the mechanochemical properties of ABCE1, a conserved mechanism in archaea and eukaryotes is suggested that couples translation termination to recycling, and eventually to re-initiation.     

Observation of high-energy neutrinos using Cerenkov detectors embedded deep in Antarctic ice

Neutrinos are elementary particles that carry no electric charge and have little mass. As they interact only weakly with other particles, they can penetrate enormous amounts of matter, and therefore have the potential to directly convey astrophysical information from the edge of the Universe and from deep inside the most cataclysmic high-energy regions. The neutrino's great penetrating power, however, also makes this particle difficult to detect. Underground detectors have observed low-energy neutrinos from the Sun and a nearby supernova, as well as neutrinos generated in the Earth's atmosphere. But the very low fluxes of high-energy neutrinos from cosmic sources can be observed only by much larger, expandable detectors in, for example, deep water or ice. Here we report the detection of upwardly propagating atmospheric neutrinos by the ice-based Antarctic muon and neutrino detector array (AMANDA). These results establish a technology with which to build a kilometre-scale neutrino observatory necessary for astrophysical observations.     

Structure of the signal recognition particle interacting with the elongation-arrested ribosome

Cotranslational translocation of proteins across or into membranes is a vital process in all kingdoms of life. It requires that the translating ribosome be targeted to the membrane by the signal recognition particle (SRP), an evolutionarily conserved ribonucleoprotein particle. SRP recognizes signal sequences of nascent protein chains emerging from the ribosome. Subsequent binding of SRP leads to a pause in peptide elongation and to the ribosome docking to the membrane-bound SRP receptor. Here we present the structure of a targeting complex consisting of mammalian SRP bound to an active 80S ribosome carrying a signal sequence. This structure, solved to 12 A by cryo-electron microscopy, enables us to generate a molecular model of SRP in its functional conformation. The model shows how the S domain of SRP contacts the large ribosomal subunit at the nascent chain exit site to bind the signal sequence, and that the Alu domain reaches into the elongation-factor-binding site of the ribosome, explaining its elongation arrest activity.