Revisiting CO2 emissions convergence in G18 countries

This study revisits whether CO₂ emissions converge in G18 countries over the period of 1950–2013. To work on this empirical analysis, we employ a more powerful quantile unit root test with per capita CO₂ emissions. While conventional unit root tests fail to reject convergence in CO₂ emissions in these G18 countries, quantile unit root test results demonstrate CO₂ emissions converged in 5 of these G18 countries (i.e., Australia, Brazil, Canada, Germany, and India). Our empirical results have important policy implications for the governments of G18 countries to direct efficient and effective energy policies to reduce the CO₂ emissions.     

再加工工艺对N18锆合金板残余应力的影响

采用“热轧+冷轧+退火”工艺对N18锆合金板进行再加工,通过X射线法分析板的表面残余应力,采用EBSD技术分析晶界取向差角分布和大小角度晶界。结果表明,热轧后N18锆合金板的表面残余应力呈现无规律分布状态;冷轧后板的表面残余应力均为压应力,其大小随着冷轧变形量的增加而增加;退火后板的表面残余应力值处于较低水平,当退火制度为500 ℃×2 h时,残余应力处于最低水平;退火后,板的微观结构以小角度晶界为主,且随着退火温度的升高,小角度晶界的密度先增加后趋于稳定。     

水平衡法与高温转化法在矿泉水氢氧稳定同位素测定中的应用

为了鉴别不同品牌矿泉水标注水源地信息真伪,对11种不同品牌饮用水的氢氧稳定同位素(δD和δ18 O)进行测定。结果表明,水平衡法(GasBench-IRMS)和高温转化法(TC/EA-IRMS)的测定结果一致性较好,两种方法测定6种不同饮用水的δD和δ18 O的平均差异分别为(0.6±1.59)‰和(0.02±0.13)‰。水平衡法需要较长的制备和测定时间,但δD和δ18 O的测定精度明显优于高温转化法。11种饮用水δD和δ18 O变化范围较大,其δD和δ18 O受不同品牌饮用水的水源地降水影响形成明显的地域性。虽然无法区分矿泉水是否由其他类别饮用水伪造,但δD和δ18 O可以为特定区域(如高海拔与沿海地区)以及产地相近的矿泉水水源地鉴别提供依据。     

Glucosamine Extends the Lifespan of Caenorhabditis elegans via Autophagy Induction

Glucosamine (GlcN) is commonly used as a dietary supplement to promote cartilage health in humans. We previously reported that GlcN could induce autophagy in cultured mammalian cells. Autophagy is known to be involved in the prevention of various diseases and aging. Here, we showed that GlcN extended the lifespan of the nematode Caenorhabditis elegans by inducing autophagy. Autophagy induction by GlcN was demonstrated by western blotting for LGG-1 (an ortholog of mammalian LC3) and by detecting autophagosomal dots in seam cells by fluorescence microscopy. Lifespan assays revealed that GlcN-induced lifespan extension was achieved with at least 5 mM GlcN. A maximum lifespan extension of approximately 30 % was achieved with 20 mM GlcN (p<0.0001). GlcN-induced lifespan extension was not dependent on the longevity genes daf-16 and sir-2.1 but dependent on the autophagy-essential gene atg-18. Therefore, we suggest that oral administration of GlcN could help delay the aging process via autophagy induction.     

Synthesis and Initial Characterization of a Selective,Pseudo-irreversible Inhibitor of Human Butyrylcholinesterase as PET Tracer

The enzyme butyrylcholinesterase (BChE) represents a promising target for imaging probes to potentially enable early diagnosis of neurodegenerative diseases like Alzheimer's disease (AD) and to monitor disease progression in some forms of cancer. In this study, we present the design, facile synthesis, in vitro and preliminary ex vivo and in vivo evaluation of a morpholine-based, selective inhibitor of human BChE as a positron emission tomography (PET) tracer with a pseudo-irreversible binding mode. We demonstrate a novel protecting group strategy for ¹⁸F radiolabeling of carbamate precursors and show that the inhibitory potency as well as kinetic properties of our unlabeled reference compound were retained in comparison to the parent compound. In particular, the prolonged duration of enzyme inhibition of such a morpholinocarbamate motivated us to design a PET tracer, possibly enabling a precise mapping of BChE distribution.     

冲击载荷下TC18钛合金力学性能模拟研究

TC18钛合金在退火状态下的屈服强度非常高,进行动态力学性能测试存在一定困难,可优先考虑采用数值模拟方法对其动态力学性能进行研究,而数值模拟结果的精确性主要取决于合金本构方程的精确性。为了减少数值模拟与实验结果之间的差异,在Johnson-Cook模型的基础上做了调整,利用ABAQUS软件的子程序接口自定义了材料本构子程序UMAT,以代码的形式来扩展ABAQUS程序的功能。通过与ABAQUS/Standard软件分析结果以及实验结果的对比,验证了自定义材料本构子程序UMAT计算结果的精确性与可靠性。该研究可为TC18钛合金的结构设计提供参考。     

Translesion Synthesis or Repair by Specialized DNA Polymerases Limits Excessive Genomic Instability upon Replication Stress

DNA can experience “replication stress”, an important source of genome instability, induced by various external or endogenous impediments that slow down or stall DNA synthesis. While genome instability is largely documented to favor both tumor formation and heterogeneity, as well as drug resistance, conversely, excessive instability appears to suppress tumorigenesis and is associated with improved prognosis. These findings support the view that karyotypic diversity, necessary to adapt to selective pressures, may be limited in tumors so as to reduce the risk of excessive instability. This review aims to highlight the contribution of specialized DNA polymerases in limiting extreme genetic instability by allowing DNA replication to occur even in the presence of DNA damage, to either avoid broken forks or favor their repair after collapse. These mechanisms and their key regulators Rad18 and Polθ not only offer diversity and evolutionary advantage by increasing mutagenic events, but also provide cancer cells with a way to escape anti-cancer therapies that target replication forks.     

The power average operator for unbalanced linguistic term sets

In order to aggregate linguistic values of unbalanced linguistic term sets, this paper introduces the linguistic proportional 2-tuple power average operator, which can reflect the relationship among the aggregated values by considering the support for each value from others. Its advantage regarding other linguistic power average operators enables it to be used in such cases in which the linguistic term sets are not necessarily to be balanced, and the membership functions of the linguistic terms are utilized in the computational processes. In this operator, a linguistic proportional 2-tuple is represented by a normalized numerical representation. Some properties of the operator are discussed. A group decision making model based on the proposed operator is introduced. Finally an illustrative example is presented.     

Stable isotope and fatty acid compositions of monovarietal olive oils: Implications of ripening stage and climate effects as determinants in traceability studies

The quantitative variability of isotopic and fatty acid compositions in extra virgin olive oil was investigated in relation to variety, olive ripeness index and geographical origin. The study was carried out in two environments of Umbria region (central Italy), differing in annual/seasonal temperatures and rainfalls. Significant correlation was found between oil isotope compositions and climatic seasonal changes during fruit ripening. Moreover, significant isotopic differences among cultivars were related to the period of maximum oil accumulation in the fruits and to the fatty acid profile. A carbon kinetic isotopic effect could be associated with the fatty acid elongation from palmitic to stearic acid and to the unsaturation step leading from oleic to linoleic. No correlation was found between stable isotope and fatty acid compositions during fruit ripening. The analyzed cultivar and ripening effects on oil traceability issues are discussed in order to focus the resolution power of stable isotope methodologies and the possibility to distinguish monovarietal oils from the same area.     

1Cr18Ni9Ti激光选区熔化成形工艺参数对致密度的影响

采用正交试验,结合典型缺陷形成原因和微观组织,研究了激光选区熔化成形工艺参数(激光功率、扫描速度和扫描间距)对1Cr18Ni9Ti不锈钢致密度的影响,分析了各工艺参数对致密度的影响规律。结果表明,粉末熔化的能量输入密度主要取决于激光功率和扫描速度;在激光功率325~340 W、扫描速度1 000~1 200 mm/s、扫描间距0.12 mm的工艺参数下,SLM技术可制备致密度高于99.9%的1Cr18Ni9Ti不锈钢零件。采用优化后的SLM工艺参数成形1Cr18Ni9Ti不锈钢试棒的力学性能优于QJ501A-98标准,抗拉强度Rm≥709 MPa,屈服强度Rp0.2≥547 MPa,断后伸长率A≥41%。