science, volume 38,issue 6673,24 nov 2023
《科学》第382卷，6673期，2023年11月24日
物理学physics
shot noise in a strange metal
奇异金属中的射击噪声
▲ 作者：liyang chen, dale t. lowder, emine bakali, aaron maxwell andrews, werner schrenk, monika waas, robert svagera, gaku eguchi, lukas prochaska, and douglas natelson
▲ 链接：
▲ 摘要：
科学家在从高温超导体到重费米子金属的各种材料中都观察到了奇怪的金属行为。在传统金属中，电流由准粒子携带。尽管有人认为奇异金属中不存在准粒子，但缺乏直接的实验证据。
研究者测量了散粒噪声，以探测重费米子奇异金属ybrh2si2纳米线中载流激发的粒度。与传统金属相比，这些纳米线的散粒噪声得到了强烈抑制。
这种抑制不能归因于费米液体中的电子-声子或电子-电子相互作用，这表明电流不是由他们探测的奇异金属体系中明确定义的准粒子携带的。研究为其他奇异金属的类似研究奠定了基础。
▲ abstract：
strange-metal behavior has been observed in materials ranging from high-temperature superconductors to heavy fermion metals. in conventional metals, current is carried by quasiparticles; although it has been suggested that quasiparticles are absent in strange metals, direct experimental evidence is lacking. we measured shot noise to probe the granularity of the current-carrying excitations in nanowires of the heavy fermion strange metal ybrh2si2. when compared with conventional metals, shot noise in these nanowires is strongly suppressed. this suppression cannot be attributed to either electron-phonon or electron-electron interactions in a fermi liquid, which suggests that the current is not carried by well-defined quasiparticles in the strange-metal regime that we probed. our work sets the stage for similar studies of other strange metals.
化学chemistry
ascreening strategy for developing thermoelectric interface materials
开发热电界面材料的筛选策略
▲ 作者：liangjun xie, li yin, yuan yu, guyang peng, shaowei song, pingjun ying, songting cai, yuxin sun, wenjing shi, and jiehe sui
▲ 链接：
▲ 摘要：
热电模块可将废热转化为电能，但寻找热电材料和电极之间的材料具有挑战性，因为不合适的界面材料可能会导致热电模块失效。研究者开发了一种筛选策略，用于分离化学上更复杂的界面候选材料。
利用这种策略，他们发现了一种镁-铜-锑半金属，它是特定类型高性能热电模块的优异界面材料。这种方法应该适用于广泛的材料化学。
▲ abstract：
thermoelectric modules convert waste heat into electricity, but finding materials that go in between the thermoelectric material and the electrodes is challenging because inappropriate interface materials can drive failure of the thermoelectric module. xie et al. developed a screening strategy for isolating more chemically complex interface candidate materials. using this strategy, the authors identified a magnesium–copper–antimony semimetal that is an excellent interface material for a specific type of high-performance thermoelectric module. this approach should apply to a wide range of material chemistries.
dissolution enables dolomite crystal growth near ambient conditions
溶解使白云石晶体在接近环境条件下生长
▲ 作者：joonsoo kim, yuki kimura, brian puchala, tomoya yamazaki, udo becker, and wenhao sun
▲ 链接：
▲ 摘要：
晶体可以在过饱和溶液中生长。一个反例是白云石 camg(co3)2，这是一种非常丰富的沉积矿物，在环境条件下不易生长，即使在高度过饱和的溶液中也不易生长。
新研究使用原子模拟表明，白云石最初沉淀出阳离子无序表面，其中高表面应变抑制进一步的晶体生长。
然而，轻度欠饱和会优先溶解这些无序区域，从而在再沉淀时增加有序性。研究者通过模拟预测，溶液在过饱和和欠饱和之间的频繁循环可以使白云石生长加速多达7个数量级。
他们用原位液体细胞透射电子显微镜验证了这一理论，直接观察溶解脉冲后块状白云石的生长。这解释了为什么现代白云石主要存在于酸碱值或盐度波动的自然环境中。它揭示了通过刻意的温和溶解期可以促进无缺陷晶体的生长和成熟。
▲ abstract：
crystals grow in supersaturated solutions. a mysterious counterexample is dolomite camg(co3)2, a geologically abundant sedimentary mineral that does not readily grow at ambient conditions, not even under highly supersaturated solutions. using atomistic simulations, we show that dolomite initially precipitates a cation-disordered surface, where high surface strains inhibit further crystal growth. however, mild undersaturation will preferentially dissolve these disordered regions, enabling increased order upon reprecipitation. our simulations predict that frequent cycling of a solution between supersaturation and undersaturation can accelerate dolomite growth by up to seven orders of magnitude. we validated our theory with in situ liquid cell transmission electron microscopy, directly observing bulk dolomite growth after pulses of dissolution. this mechanism explains why modern dolomite is primarily found in natural environments with ph or salinity fluctuations. more generally, it reveals that the growth and ripening of defect-free crystals can be facilitated by deliberate periods of mild dissolution.
deconvolving microbial and environmental controls on marine sedimentary pyrite sulfur isotope ratios
海相沉积黄铁矿硫同位素比值的反褶络微生物和环境控制
▲ 作者：r. n. bryant, j. l. houghton, c. jones, v. pasquier, i. halevy, and d. a. fike
▲ 链接：
▲ 摘要：
在海洋沉积物和沉积岩中发现的黄铁矿的硫同位素组成经常被用来试图重建碳、氧和硫的耦合循环。
然而，由此产生的解释可能会因物理和生物过程的相互竞争而变得复杂。作者研究表明，沉积环境中的无机反应和输运，而不是微生物的影响，导致观测到的硫同位素值范围很广。
在地球历史的大部分时间里，观测到的硫酸盐-黄铁矿同位素分异的增加主要反映了海洋硫酸盐浓度增加的影响，但在过去的5.5亿年里，超大陆的分裂和组装以及海平面的变化更为重要。
▲ abstract：
the sulfur isotope composition of pyrite found in marine sediments and sedimentary rocks is often used to try to reconstruct the coupled cycles of carbon, oxygen, and sulfur. however, the resulting interpretations can be complicated by the competing effects of physical and biological processes. halevy et al. show that inorganic reactions and transport in depositional environments, rather than microbial influence, leads to the wide range of sulfur isotopic values observed. the observed increase in sulfate–pyrite isotope fractionation over most of earth’s history primarily reflects the effects of increasing marine sulfate concentration, except over the past 550 million years, when supercontinent breakup and assembly and variations in sea level were more important.
生物物理学和生物化学biophysics & biochemistry
air channels create a directional light signal to regulate hypocotyl phototropism
空气通道产生定向光信号调节下胚轴向光性
▲ 作者：ganesh m. nawkar, martina legris, anupama goyal, emanuel schmid-siegert, jérémy fleury, antonio mucciolo, damien de bellis, martine trevisan, andreas schueler, and christian fankhauser
▲ 链接：
▲ 摘要：
在植物中，光的方向是由趋光素感光受体感知的，它触发定向生长反应，称为趋光性。
然而，光学组织特性在功能上对趋光性的贡献仍不清楚。作者研究表明细胞间的空气通道限制了光通过几个物种的不同器官的透射率。空气通道增强拟南芥下胚轴的光散射，从而使光梯度变陡。这是拟南芥和芸苔类植物有效的致光性反应所必需的。
他们发现了一种胚性表达的abc转运蛋白，这是幼苗中存在空气通道及其周围结构所必需的。该研究为细胞间空气空间的发展或维持提供了见解，并确定了植物定向光感知的机制。
▲ abstract：
in plants, light direction is perceived by the phototropin photoreceptors, which trigger directional growth responses known as phototropism. however, the optical tissue properties that functionally contribute to phototropism remain unclear. in this work, we show that intercellular air channels limit light transmittance through various organs in several species. air channels enhance light scattering in arabidopsis hypocotyls, thereby steepening the light gradient. this is required for an efficient phototropic response in arabidopsis and brassica. we identified an embryonically expressed abc transporter required for the presence of air channels in seedlings and a structure surrounding them. our work provides insights into intercellular air space development or maintenance and identifies a mechanism of directional light sensing in plants.
palladium catalysis enables cross-coupling–like sn2-glycosylation of phenols
钯催化可实现酚类交叉偶联的sn2糖基化
▲ 作者：li-fan deng, yingwei wang, shiyang xu, ao shen, hangping zhu, siyu zhang, xia zhang, and dawen niu
▲ 链接：
▲ 摘要：
糖基化是许多天然产物的一个重要特征，但安装糖的方法可能会受到立体特异性的限制，因为许多反应是通过氧碳鎓中间体进行的，其中立体化学会丢失。研究者开发了一种用于酚糖基化的多功能钯催化反应，类似于钯催化的芳基碳-氧交叉偶联反应。
钯氧化加成到易于制备的邻碘联苯 s-糖苷上，产生一种复合物，该复合物通过 sn2机制与多种酚盐反应，产生立体化学反转的糖基化酚。该反应适用于（但不限于）2-脱氧糖，并且可以与其他钯催化的交叉偶联在一锅中进行，以产生复杂的 o-糖苷。
▲ abstract：
glycosylations are an important feature of many natural products, but methods to install sugars can suffer from limitations on stereospecificity because many reactions proceed through an oxocarbenium intermediate in which stereochemistry is lost. deng et al. developed a versatile palladium-catalyzed reaction for the glycosylation of phenols that resembles palladium-catalyzed aryl carbon–oxygen cross-coupling reactions. palladium oxidative addition to an easily prepared ortho-iodobiphenyl s-glycoside yields a complex that reacts with a wide range of phenolates through a sn2 mechanism to afford the glycosylated phenols with inversion of stereochemistry. this reaction works well with, but it is not limited to, 2-deoxy sugars and can be performed in one pot with other palladium-catalyzed cross-couplings to yield complex o-glycosides.
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