编译|冯维维
science, volume 386,issue 6718,11 oct 2024
《科学》第386卷，6718期，2024年10月11日
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生态ecology
hidden comet tails of marine snow impede ocean-based carbon sequestration
“海洋雪”中的隐藏“彗尾”有碍海洋碳封存
▲ 作者：rahul chajwa, eliott flaum, kay d. bidle, benjamin van mooy, and manu prakash
▲链接：
https://www.science.org/doi/10.1126/science.adl5767
▲摘要：
下沉的海洋微粒有机物质，通常被称为“海洋雪”，将大量的碳从海洋表面转移到深处，构成了地球碳循环的主要组成部分之一。这些粒子的生物和物理复杂性，及其运动中所涉及的长度和时间尺度的广泛范围，使得详细确定它们的动力学变得极其困难。
chajwa等人使用显微成像技术发现，这些颗粒普遍表现出尾巴状的流动形态，这极大地影响了它们的运动以及它们在深海中封存了多少碳。
▲ abstract：
sinking marine particulate organic matter, commonly called “marine snow,” moves huge amounts of carbon from the new-surface ocean to depth, constituting one of the major components of earth’s carbon cycle. the biological and physical complexity of these particles, together with the wide range of lengths and timescales that are involved in their motion, have made it exceedingly difficult to determine their dynamics in detail. chajwa et al. used microscopic imaging to show that these particles universally exhibit a tail-like flow morphology that greatly influences their movement and how much carbon they sequester in the deep ocean.
ecological speciation in darwin’s finches: ghosts of finches future
达尔文雀的生态物种形成：雀类未来的幽灵
▲ 作者：jeffrey podos and katie m. schroeder
▲链接：
https://www.science.org/doi/10.1126/science.adj4478
▲摘要：
当我们想到一个物种适应环境变化时，通常会想到一个特征。然而，一个特征的改变可能会影响到其他特征。在galapagos雀类中，已经证明干旱会导致喙的大小和形状发生变化，以响应种子资源的变化。
然而，鸟类不仅用喙吃饭，还用喙唱歌。podos和schroeder预测了鸟的大小如何随着一系列干旱而变化，并预测了它们会发出的歌曲。他们发现，在一系列模拟干旱之后，这些歌曲的差异足够大，以至于领地雄性鸟类不再识别它们。
▲ abstract：
when we think of a species adapting to environmental change, we mostly think about one trait. however, changes in one trait will likely affect others. in galápagos finches, it has been shown that drought can lead to a change in bill size and shape in response to shifts in seed resources. however, birds do not just eat with their bills, they also sing with them. podos and schroeder predicted how bill size would change in response to a series of droughts and forecasted the songs that they would produce. they found that, after a series of simulated droughts, the songs differed enough that territorial male birds no longer recognized them.
化学chemistry
catalytic asymmetric fragmentation of cyclopropanes
环丙烷催化不对称裂解
▲ 作者：ravindra krushnaji raut, satoshi matsutani, fuxing shi, shuta kataoka, margareta poje, benjamin mitschke, satoshi maeda, nobuya tsuji , and benjamin list
▲链接：
https://www.science.org/doi/10.1126/science.adp9061
▲摘要：
过去半个世纪，有机化学家设计了许多催化剂，它们只能产生两种可能的镜像（对映体）产物中的一种。大多数情况下，这些催化剂依赖于氧或氮原子的结合位点。随着反应的进行，缺乏这些位点的纯碳氢化合物很难在空间上产生偏差。
研究者报道了一类手性酸，咪胺二磷酰亚胺酸，可以包裹对称的环丙烷并催化其开环重排，以传递具有高对映选择性的手性烯烃化合物。
▲ abstract：
over the past half-century, organic chemists have devised numerous catalysts that deliver just one of two possible mirror-image (enantiomeric) products. for the most part, these catalysts rely on binding sites with oxygen or nitrogen atoms; pure hydrocarbons lacking such sites are much harder to bias spatially as the reaction ensues. raut et al. now report that a class of chiral acids, imidodiphosphorimidates, can envelop symmetrical cyclopropanes and catalyze their ring-opening rearrangement to deliver chiral olefinic compounds with high enantioselectivity.
catalytic prenyl conjugate additions for synthesis of enantiomerically enriched ppaps
催化戊烯基共轭加成物合成对映体富集ppaps
▲ 作者：shawn ng, casey howshall, thanh nhat ho, binh khanh mai, yuebiao zhou, can qin, kai ze tee, peng liu, filippo romiti, and amir h. hoveyda
▲链接：
https://www.science.org/doi/10.1126/science.adr8612
▲摘要：
戊烯基是一种疏水的五碳片段，在生物化学和天然产物化学中广泛存在。具有广泛药用价值的天然产品——多环聚戊烯基酰基间苯三酚（ppaps），一直是多个合成研究的目标，但不对称地引入戊烯基已被证明是一个持久的挑战。
ng等人报道了一种铜催化的方法，使不饱和酮戊酰化，从而获得具有高对映选择性的ppap。该方法的关键是一种有机硼酸盐试剂，硼在一个有点违反直觉的位置。
▲ abstract：
the prenyl group is a hydrophobic five-carbon fragment common across a wide range of contexts in biochemistry and natural product chemistry. one extensive class of natural products of pharmaceutical interest, polycyclic polyprenylated acylphloroglucinols (ppaps), has been the target of multiple synthetic studies, but the introduction of the prenyl groups asymmetrically has proven to be an enduring challenge. ng et al. now report a copper-catalyzed method to prenylate unsaturated ketones and thereby access ppaps with high enantioselectivity. key to the method is an organoborate reagent with the boron in a somewhat counterintuitive position.
物理学physics
direct optical measurement of intramolecular distances with angstrom precision
用埃精度直接光学测量分子内距离
▲ 作者：steffen j. sahl, jessica matthias, kaushik inamdar, michael weber, taukeer a. khan, christian brüser, stefan jakobs, stefan becker, christian griesinger, and stefan w. hell
▲链接：
https://www.science.org/doi/10.1126/science.adj7368
▲摘要：
在纳米尺度上直接测量距离对光学技术来说是一个挑战，即使对那些使用亚衍射分辨率荧光显微镜的人来说也是如此。sahl等人改进了一种名为minflux的光学方法，可以精确测量1~10纳米范围内的分子内距离，而对于倾斜的分子，则可以测量1纳米以下的分子内距离。他们使用聚脯氨酸尺，演示了具有已知个位数纳米间距的荧光团的分辨率。
他们将这种方法应用于光活化染料标记的蛋白质的大分子间和大分子内测量，包括距离对目前的间接方法来说太短。成像实验证明了该技术在研究细胞中蛋白质-蛋白质相互作用方面的潜力。
▲ abstract：
measuring distances directly at the nanometer scale is a challenge for optical techniques, even for those using subdiffraction-resolution fluorescence microscopy. sahl et al. refined an optical approach called minflux such that they could measure precise intramolecular distances in the 1- to 10-nanometer range and below 1 nanometer for molecules with a tilt. using a polyproline ruler, the authors demonstrate resolution of fluorophores with known single-digit nanometer spacing. they applied this approach to inter- and intramacromolecular measurements of proteins labeled with photoactivatable dyes, including distances too short for current indirect methods. imaging experiments demonstrated the potential of this technique to study protein-protein interactions in cells.
polar and quasicrystal vortex observed in twisted-bilayer molybdenum disulfide
扭曲双层二硫化钼中观察到极性和准晶涡旋
▲ 作者：chi shing tsang, xiaodong zheng, tong yang, zhangyuan yan, wei han, lok wing wong, haijun liu, shan gao, ka ho leung, and thuc hue ly
▲链接：
https://www.science.org/doi/10.1126/science.adp7099
▲摘要：
对扭曲二硫化钼（mos2）双分子层中电场的观察揭示了与扭曲角有关的面内手性涡域。
tsang等人使用四维扫描透射电子显微镜和第一性原理计算来确定局部极性域结构，这可能是由扭曲堆叠引起的电荷重新分配和小的平面内离子位移引起的。大扭角处可见马赛克手性涡。一个12层的准晶体双层具有复杂的涡旋图案，可以通过在显微镜下置换层来调整。
▲ abstract：
observations of electric fields in twisted molybdenum disulfide bilayers have revealed in-plane chiral vortex domains that depend on the twist angle. tsang et al. used four-dimensional scanning transmission electron microscopy (tem) and first-principles calculations to determine local polar domain structures, which may arise from twist stacking-induced charge redistribution and small in-plane ionic displacements. mosaic chiral vortex patterns were seen for large twist angles. a 12-fold quasicrystal bilayer had complex vortex patterns that could be tuned by displacing layers within the microscope.
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