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崖州湾种子实验室里，海南大学在读博士研究生杜梅正在研究水稻氮肥高效利用。“海南独特的气候条件可以大大加快水稻研究的步伐，加上科技城产学研结合紧密，从理论知识到生产实践可以无缝衔接，科研成果能够快速转化。”杜梅说。
2025年01月11日，4.王岗坪
联合早报中文网-飞飞飞.耻苍颈锄飞.肠辞尘冲名站在线
《科学》（20221028出版）一周论文导读2022-10-31 14:21·科学网编译 | 未玖Science, 28 OCTOBER 2022, VOL 378, ISSUE 6618《科学》2022年10月28日第378卷6618期天文学AstronomyLargest recent impact craters on Mars: Orbital imaging and surface seismic co-investigation火星上最近最大的撞击坑：轨道成像和表面地震联合调查▲ 作者：L. V. POSIOLOVA, P. LOGNONN?, W. B. BANERDT, J. CLINTON, G. S. COLLINS, T. KAWAMURA, ET AL.▲ 链接：https://www.science.org/doi/10.1126/science.abq7704▲ 摘要：2021年下半年火星上形成了两个直径>130米的撞击坑这是火星侦察轨道飞行器自16年前开始运行以来发现的两个最大的新撞击坑该撞击造成了洞察号在其3年任务期间记录的两次最大地震事件（震级大于4级）轨道图像和地震地面运动的结合使人们能够研究大气稀薄行星撞击过程的地下和大气能量分配并首次直接测试已知事件距离的火星深部-内部地震模型35°N的撞击处挖出了大块的水冰这是在火星上直接观察到冰的最低纬度▲ Abstract：Two >130-meter-diameter impact craters formed on Mars during the later half of 2021. These are the two largest fresh impact craters discovered by the Mars Reconnaissance Orbiter since operations started 16 years ago. The impacts created two of the largest seismic events (magnitudes greater than 4) recorded by InSight during its 3-year mission. The combination of orbital imagery and seismic ground motion enables the investigation of subsurface and atmospheric energy partitioning of the impact process on a planet with a thin atmosphere and the first direct test of martian deep-interior seismic models with known event distances. The impact at 35°N excavated blocks of water ice, which is the lowest latitude at which ice has been directly observed on Mars.Surface waves and crustal structure on Mars火星表面波和地壳结构▲ 作者：D. KIM, W. B. BANERDT, S. CEYLAN, D. GIARDINI, V. LEKI?, P. LOGNONN?, ET AL.▲ 链接：https://www.science.org/doi/10.1126/science.abq7157▲ 摘要：研究组探测到火星上两颗陨石撞击产生的表面波通过测量撞击着陆器路径上的群速度弥散他们获得了远离洞察号着陆器的地壳结构的直接约束条件赤道二分线以北的地壳在5~30千米深度范围内的横波速度约为每秒3.2千米深度变化不大这意味着着陆器下方的地壳密度比推测的要高表明表面波穿过的火山区域要么成分不同要么孔隙度减少在着陆点下方10千米深处观察到较低的速度和地壳分层并非一个全球性特征表面波揭示的结构变化对火星地壳形成和厚度的模型具有重要意义▲ Abstract：We detected surface waves from two meteorite impacts on Mars. By measuring group velocity dispersion along the impact-lander path, we obtained a direct constraint on crustal structure away from the InSight lander. The crust north of the equatorial dichotomy had a shear wave velocity of approximately 3.2 kilometers per second in the 5- to 30-kilometer depth range, with little depth variation. This implies a higher crustal density than inferred beneath the lander, suggesting either compositional differences or reduced porosity in the volcanic areas traversed by the surface waves. The lower velocities and the crustal layering observed beneath the landing site down to a 10-kilometer depth are not a global feature. Structural variations revealed by surface waves hold implications for models of the formation and thickness of the martian crust.材料科学Materials SciencePlastic deformation in silicon nitride ceramics via bond switching at coherent interfaces氮化硅陶瓷在共格界面上通过键切换产生塑性变形▲ 作者：JIE ZHANG, GUANGHUA LIU, WEI CUI, YIYAO GE, SONGMO DU, YIXUAN GAO, ET AL.▲ 链接：https://www.science.org/doi/10.1126/science.abq7490▲ 摘要：共价键合陶瓷具有优异的性能（包括硬度、强度、化学惰性、耐热性和耐腐蚀性）但由于其室温脆性如何实现更广泛的应用颇具挑战与金属中的原子可以沿着滑移面滑动以变形不同共价键合陶瓷由于原子间共价键的强定向性其变形需要断键这最终会导致加载时发生断裂研究组提出了一种可变形共价键合氮化硅（Si3N4）陶瓷的设计方法其特点是具有共格界面的双相结构在共格界面上实现了连续键切换这有利于应力诱导相变并最终产生塑性变形能力▲ Abstract：Covalently bonded ceramics exhibit preeminent properties—including hardness, strength, chemical inertness, and resistance against heat and corrosion—yet their wider application is challenging because of their room-temperature brittleness. In contrast to the atoms in metals that can slide along slip planes to accommodate strains, the atoms in covalently bonded ceramics require bond breaking because of the strong and directional characteristics of covalent bonds. This eventually leads to catastrophic failure on loading. We present an approach for designing deformable covalently bonded silicon nitride (Si3N4) ceramics that feature a dual-phase structure with coherent interfaces. Successive bond switching is realized at the coherent interfaces, which facilitates a stress-induced phase transformation and, eventually, generates plastic deformability.化学ChemistryStereochemical editing logic powered by the epimerization of unactivated tertiary stereocenters未激活三级立体中心的差向异构助力立体化学编辑逻辑▲ 作者：YU-AN ZHANG, VIGNESH PALANI, ALEXANDER E. SEIM, YONG WANG, KATHLEEN J. WANG AND ALISON E. WENDLANDT.▲ 链接：https://www.science.org/doi/10.1126/science.add6852▲ 摘要：复杂目标物的立体选择性合成需要精确的化学转换协调同时建立所需键的连通性和空间定向在这项工作中研究组描述了一种手性分子及其异构体合成的互补范式即在后期调整分子的三维结构这一策略成功的关键是开发了一种温和且高度通用的光催化方法它由十钨酸盐聚阴离子和二硫化物助催化剂组成使先前构型固定的未激活三级生成中心实现相互转化研究组通过快速构建使用现有工具很难制备的手性支架以及复杂目标物的后期立体编辑展示了这种方法的多功能性（以及立体编辑逻辑的实现）▲ Abstract：The stereoselective synthesis of complex targets requires the precise orchestration of chemical transformations that simultaneously establish the connectivity and spatial orientation of desired bonds. In this work, we describe a complementary paradigm for the synthesis of chiral molecules and their isomers, which tunes the three-dimensional structure of a molecule at a late stage. Key to the success of this strategy is the development of a mild and highly general photocatalytic method composed of decatungstate polyanion and disulfide cocatalysts, which enable the interconversion of unactivated tertiary stereogenic centers that were previously configurationally fixed. We showcase the versatility of this method—and the implementation of stereoediting logic—by the rapid construction of chiral scaffolds that would be challenging to access using existing tools and by the late-stage stereoediting of complex targets.Closed-loop optimization of general reaction conditions for heteroaryl Suzuki-Miyaura coupling杂芳基Suzuki-Miyaura偶联反应通用条件的闭环优化▲ 作者：NICHOLAS H. ANGELLO, VANDANA RATHORE, WIKTOR BEKER, AGNIESZKA WO?OS, EDWARD R. JIRA, RAFA? ROSZAK, ET AL.▲ 链接：https://www.science.org/doi/10.1126/science.adc8743▲ 摘要：有机反应的通用条件很重要但却罕见确定它们的努力通常只考虑化学空间的狭窄区域要发现更通用的反应条件就需要考虑从大矩阵基质和高维反应条件基质交叉而成的化学空间的广阔区域这使得详尽的实验不切实际研究组报道了一个简单的闭环工作流利用数据引导矩阵向下选择、不确定性最小化机器学习和机器人实验来发现通用反应条件应用于杂芳基Suzuki-Miyaura交叉偶联这种极具挑战性和重要性的问题时研究组确定了一个通用条件与之前使用传统方法开发的广泛使用的基准相比平均产率翻了一番该研究为解决具有大搜索空间的多维化学优化问题提供了一个实用的路线图▲ Abstract：General conditions for organic reactions are important but rare, and efforts to identify them usually consider only narrow regions of chemical space. Discovering more general reaction conditions requires considering vast regions of chemical space derived from a large matrix of substrates crossed with a high-dimensional matrix of reaction conditions, rendering exhaustive experimentation impractical. Here, we report a simple closed-loop workflow that leverages data-guided matrix down-selection, uncertainty-minimizing machine learning, and robotic experimentation to discover general reaction conditions. Application to the challenging and consequential problem of heteroaryl Suzuki-Miyaura cross-coupling identified conditions that double the average yield relative to a widely used benchmark that was previously developed using traditional approaches. This study provides a practical road map for solving multidimensional chemical optimization problems with large search spaces.公共卫生Public HealthEvolution and antiviral activity of a human protein of retroviral origin逆转录病毒来源人类蛋白质的进化和抗病毒活性▲ 作者：JOHN A. FRANK, MANVENDRA SINGH, HARRISON B. CULLEN, RAPHAEL A. KIROU, MERIEM BENKADDOUR-BOUMZAOUAD, JOSE L. CORTES, ET AL.▲ 链接：https://www.science.org/doi/10.1126/science.abq7871▲ 摘要：内源性逆转录病毒是源自古老种系感染的哺乳动物基因组的丰富组成部分在一些哺乳动物中由这些元件编码的包膜蛋白可以抵御外源性病毒但这种活性在人类内源性表达的包膜中尚未被证实研究组报道人类基因组拥有大量包膜衍生序列具有抑制逆转录病毒感染的潜力为了验证这一点他们对包膜衍生蛋白Suppressyn进行了表征结果发现Suppressyn在人类着床前胚胎和发育中的胎盘中使用其祖先逆转录病毒启动子表达细胞培养分析表明Suppressyn及其类人直系同源物可抑制现存哺乳动物D型逆转录病毒的感染该数据支持宿主免疫和基因组防御的逆转录病毒包膜共选择的通用模型▲ Abstract：Endogenous retroviruses are abundant components of mammalian genomes descended from ancient germline infections. In several mammals, the envelope proteins encoded by these elements protect against exogenous viruses, but this activity has not been documented with endogenously expressed envelopes in humans. We report that the human genome harbors a large pool of envelope-derived sequences with the potential to restrict retroviral infection. To test this, we characterized an envelope-derived protein, Suppressyn. We found that Suppressyn is expressed in human preimplantation embryos and developing placenta using its ancestral retroviral promoter. Cell culture assays showed that Suppressyn, and its hominoid orthologs, could restrict infection by extant mammalian type D retroviruses. Our data support a generalizable model of retroviral envelope co-option for host immunity and genome defense.
4K 屏、双摄像头，三星 Galaxy S8 首次曝光原创2016-06-20 14:17·雷科技近两年双摄像头在手机行业非常流行，目前已有LG G5、华为P9等一批旗舰拥有该配置。而之前也有消息曝光，iPhone 7 Plus或将无缘双摄像头，这也让不少人质疑双摄像头存在的必要性。不过，显然三星还是对这一特性露出了肯定的态度。日前有消息称，三星下代S系列旗舰Galaxy S8或将拥有双摄像头，且随着VR技术的广泛应用，三星或许会在S8中加入4K分辨率显示屏。更早以前，三星就曾展示了针对手机和VR头显的4K显示屏，或许现在面临的问题就应该是其是否能够在短时间内投入量产了。（图片来源于：phonearena）VR是今年一众手机厂商的重点布局内容，三星也推出了自家VR设备。因此我们在S8上看到4K显示屏也就不足为奇了，毕竟VR头显设备对手机的屏幕分辨率要求还是比较高的。但值得三星考虑的是，随着手机分辨率的再次提升，续航问题或许会被再度放大。此前，全球首款4K屏幕手机索尼Xperia Z5 Premium，就是在特定场景下才会作为4K显示，平常则依旧为1080P。（图片来源于：technobuffalo）在S8的其他配置方面，传其将搭载骁龙830处理器。该处理器采用10nm FinFET工艺，比现有骁龙820的14nm工艺还要更先进，将会在保证性能的同时进一步节约功耗。此外，其或将依旧支持IP68级别的防水防尘。而对于这款新品的其他信息目前曝光的倒不是太多，外媒只是说可能会在明年2月之前发布。（图片来源于：samsung）显然在笔者看来，三星S8这两个方面的升级是完全合乎情理的。三星为了保持自己全球第一的地位，已经开始越来越将自己的定位朝技术方向靠拢。之前就有消息称，其将于明年推出全球首款折叠屏幕手机Galaxy X。所以，其必须要通过让人耳目一新的创新来继续推动自己走在行业的前头，显然双摄像头和VR技术成为三星关注的点。不过在三星Galaxy S8正式发布前，或许我们更加应该关注一下，即将在8月2日于美国纽约正式发布的Galaxy Note 7。（封面图来源于：ibtimes）巨大的卤池群