A supra-massive magnetar central engine for short GRB 130603B

We show that the peculiar early optical and in particular X-ray afterglow emission of the short duration burst GRB 130603B can be explained by continuous energy injection into the blastwave from a supra-massive magnetar central engine. The observed energetics and temporal/spectral properties of the late infrared bump (i.e., the "kilonova") are also found consistent with emission from the ejecta launched during an NS-NS merger and powered by a magnetar central engine. The isotropic-equivalent kinetic energies of both the GRB blastwave and the kilonova are about $E_{\rm k}\sim 10^{51}$ erg, consistent with being powered by a near-isotropic magnetar wind. However, this relatively small value demands that most of the initial rotational energy of the magnetar $(\sim {\rm a~ few \times 10^{52}~ erg})$ is carried away by gravitational wave radiation. Our results suggest that (i) the progenitor of GRB 130603B would be a NS-NS binary system, whose merger product would be a supra-massive neutron star that lasted for about $\sim 1000$ seconds; (ii) the equation-of-state of nuclear matter would be stiff enough to allow survival of a long-lived supra-massive neutron star, so that it is promising to detect bright electromagnetic counterparts of gravitational wave triggers without short GRB associations in the upcoming Advanced LIGO/Virgo era.Comment: Five pages including 1 Figure, to appear in ApJ

Movable Fiber-Integrated Hybrid Plasmonic Waveguide on Metal Film

A waveguide structure consisting of a tapered nanofiber on a metal film is proposed and analyzed to support highly localized hybrid plasmonic modes. The hybrid plasmonic mode can be efficiently excited through the in-line tapered fiber based on adiabatic conversion and collected by the same fiber, which is very convenient in the experiment. Due to the ultrasmall mode area of plasmonic mode, the local electromagnetic field is greatly enhanced in this movable waveguide, which is potential for enhanced coherence light emitter interactions, such as waveguide quantum electrodynamics, single emitter spectrum and nonlinear optics

Difference in Thermotolerance Between Green and Red Color Variants of the Japanese Sea Cucumber, Apostichopus japonicus Selenka: Hsp70 and Heat-Hardening Effect

We studied thermal tolerance limits, heat-hardening, and Hsp70 to elucidate the difference in thermotolerance between two color variants of the sea Cucumber Apostichopus japonicus. Green and Red variants Occupy different habitats and have different aestivation responses to high temperature in summer. In the absence of heat-hardening the variants showed no difference in the temperature at which 50% of the individuals died: Green 31.49 degrees C; Red, 31.39 degrees C. However. Green specimens acquired higher thermotolerance than Red after a prior Sublethal heat exposure. After 72 h of recovery from a heat-hardening treatment (30 degrees C for 2 h) the survival of Green variants was more than 50% and that of Red wits less than 5% when they were treated at 33 degrees C for 2 h. Levels of mRNA and protein for Hsp70 were significantly higher in Green than Red after the heat shock of 30 degrees C, and the stability of hsp70 mRNA of Green was significantly higher than that of Red. Our findings suggest that within the same species, different variants that have similar thermal limits in the absence of heat-hardening can acquire different thermotolerances after a prior sublethal heat shock. The difference in induced thermotolerance between Green and Red is closely related to the expression pattern of Hsp70, which was partly governed by the stability of hsp70 mRNA

Diethyl 2,6-dimethyl-4-phenyl-1,4-dihydro­pyridine-3,5-dicarboxyl­ate

The title mol­ecule, C19H23NO4, was synthesized by the reaction of benzaldehyde, ethyl acetoacetate and NH4HCO3. The dihydro­pyridine ring adopts a flattened boat conformation and the plane of the base of the boat forms a dihedral angle of 88.78 (9)° with the phenyl ring. The packing is stabilized by strong inter­molecular N—H⋯O and weak inter­molecular C—H⋯O hydrogen bonds

Thermal adaptation of enzymes

董云伟团队在潮间带生物生化适应机制的研究过程中，结合分子动力学模拟和实验调控手段，发现极端高温下，耐热滨螺能够通过增强代谢关键酶的作用，避免蛋白质的解链，保持微结构完整和功能维持；通过对原位体温跨度达60℃的12种软体动物的研究，定量了cMDH结构柔性的温度适应性变化程度，揭示了氨基酸温度适应性进化的关键位点，阐述了蛋白质结构稳定性与生物地理分布的内在联系。将海洋软体动物生化适应研究从单一的定性实验，拓展到了基于计算生物学的定量研究，揭示了海洋软体动物细胞质苹果酸脱氢酶（cMDH）结构稳定性和功能适应性的趋同进化模式，建立了基于代谢关键酶的“酶促动力学—蛋白合成—模拟计算”的生化适应机制的创新性研究模式。基于上述基础，课题组进一步拓展研究的深度与广度，比较分析了从南极洲半致死温度仅为4℃的扇贝，到中国沿海可耐受60℃以上高温的滨螺等26种海洋软体动物 cMDH 的温度耐受性，提出了蛋白质不同区域氨基酸的温度适应性变化模式，通过分子动力学分析揭示了具有重要功能的区域及其作用机制。这一系列研究成果加深了对海洋生物蛋白质温度适应机制的认识，为该领域提供了新的研究模式与思路，对于查明环境温度对生物分布的影响及其机制，预测气候变暖的生态学效应具有重要意义。董云伟团队致力于潮间带生态学研究，重点研究潮间带生物对复杂环境条件的响应特征和时空规律，及其适应机制。近年来研究主要集中在潮间带生物生化适应机制、生理调节策略及地理格局变化等方面。【Abstract】Comparative studies of orthologous proteins of species evolved at different temperatures have revealed consistent patterns of temperature-related variation in thermal stabilities of structure and function. However, the precise mechanisms by which interspecific variations in sequence foster these adaptive changes remain largely unknown. Here, we compare orthologs of cytosolic malate dehydrogenase (cMDH) from marine molluscs adapted to temperatures ranging from -1.9℃ (Antarctica) to～55℃ (South China coast) and show how amino acid usage in different regions of the enzyme (surface, intermediate depth, and protein core) varies with adaptation temperature. This eukaryotic enzyme follows some, but not all of the rules established in comparisons of archaeal and bacterial proteins. To link the effects of specific amino acid substitutions with adaptive variations in enzyme thermal stability we combined site-directed mutagenesis (SDM) and in vitro protein experimentation with in silico mutagenesis using molecular dynamics simulation (MDS) techniques. SDM and MDS methods generally, but not invariably yielded common effects on protein stability. MDS analysis is shown to provide insights into how specific amino acid substitutions affect the conformational flexibilities of mobile regions (MRs) of the enzyme that are essential for binding and catalysis. Whereas these substitutions invariably lie outside of the MRs, they effectively transmit their flexibility-modulating effects to the MRs through linked interactions among surface residues. This discovery illustrates that regions of the protein surface lying outside of the site of catalysis can help establish an enzyme’s thermal responses and foster evolutionary adaptation of function.This work was supported by National Natural Science Foundation of China Grants 41776135 and 41476115 (to Y.-w.D.) and Nature Science Funds for Distin-guished Young Scholars of Fujian Province, China Grant 2017J07003 (to Y.-w.D.). Work in the collection of the Antarctic specimens was supported by National Science Foundation Grant 1245703 (to Donal Manahan, co-PI).该成果得到国家自然科学基金项目（项目编号：41776135、41476115）和福建省杰出青年基金（2017J07003）资助