生命科学Life Science 

▲ 作者：ZHEN ZHOU, YUTING LIU, YUSHEN FENG, STEPHEN KLEPIN, LEV S. TSIMRING, LORRAINE PILLUS, JEFF HASTY, AND NAN HAO

▲ 链接：

https://www.science.org/doi/10.1126/science.add7631

▲ 摘要：

酵母细胞有一个转录开关，导致它们以两种方式中的一种死亡:一种是核仁衰退，另一种是线粒体衰变。

通过将这种转录开关重新连接到负反馈回路中，Zhou等人能够使酵母细胞在两种状态之间振荡，并将其寿命延长82%。这些结果代表了利用工程原理设计控制复杂生物性状的合成基因电路的一步。

▲ Abstract：

Yeast cells have a transcriptional toggle switch that leads them to die by one of two fates: One causes death by nucleolar decline, the other by mitochondrial decay. By rewiring this transcriptional switch into a negative-feedback loop, Zhou et al. were able to cause yeast cells to oscillate between the two states and increase their life span by 82%. These results represent a step forward toward the use of engineering principles to design synthetic gene circuits that control complex biological traits. 

▲ 作者：YONGQIANG GAO, JEREMY D. AMON, LIOR ARTZI, FERNANDO H. RAMíREZ-GUADIANA, KELLY P. BROCK, JOSHUA C. COFSKY, DEBORAH S. MARKS, ANDREW C. KRUSE, AND DAVID Z. RUDNER

▲ 链接：

https://www.science.org/doi/10.1126/science.adg9829

▲ 摘要：

细菌孢子可以抵抗抗生素和灭菌，并可在几十年内保持代谢不活跃，但它们可以迅速发芽并恢复生长以响应营养。广泛保守的受体嵌入孢子膜检测营养物质，但孢子如何转导这些信号仍不清楚。

研究者发现这些受体形成低聚膜通道。据预测，在缺乏养分的情况下，扩大通道的突变会启动发芽，而那些缩小通道的突变会阻止离子释放和对养分的反应。

在营养生长过程中，表达通道变宽的受体会导致膜电位丧失和细胞死亡，而向表达野生型受体的细胞中添加生芽则会引发膜去极化。因此，萌发受体作为营养门控离子通道，使离子释放启动退出休眠。

▲ Abstract：

Bacterial spores resist antibiotics and sterilization and can remain metabolically inactive for decades, but they can rapidly germinate and resume growth in response to nutrients. Broadly conserved receptors embedded in the spore membrane detect nutrients, but how spores transduce these signals remains unclear. Here, we found that these receptors form oligomeric membrane channels. Mutations predicted to widen the channel initiated germination in the absence of nutrients, whereas those that narrow it prevented ion release and germination in response to nutrients. Expressing receptors with widened channels during vegetative growth caused loss of membrane potential and cell death, whereas the addition of germinants to cells expressing wild-type receptors triggered membrane depolarization. Therefore, germinant receptors act as nutrient-gated ion channels such that ion release initiates exit from dormancy.　　

生物物理学Biophysics 

▲ 作者：VISHAL P. PATIL, HARRY TUAZON, EMILY KAUFMAN, TUHIN CHAKRABORTTY, DAVID QIN, J?RN DUNKEL, AND M. SAAD BHAMLA

▲ 链接：

https://www.science.org/doi/10.1126/science.ade7759

▲ 摘要：

任何一个没有把绳子卷好就打包的人都知道绳子是多么容易缠结，而要解开又是多么困难。相比之下，加利福尼亚的黑虫会在几分钟内迁移成一个纠结的球，以调节温度或湿度，但在感知到危险后，会在几毫秒内解开并散开。

作者将蠕虫的超声波研究与理论相结合，建立了一个模型，说明单个蠕虫（或细丝）的运动如何影响集体动力学。特别是，他们发现交替的螺旋波既能形成缠结，又能超快地解开缠结。研究可以为设计拓扑可调活性材料提供指导。

▲ Abstract：

Anyone who has ever packed away rope without coiling it properly knows how easily it gets tangled and how difficult it can be to untangle. By contrast, California blackworms will migrate into a tangled ball over the course of minutes to regulate temperature or moisture but then disentangle and scatter within milliseconds upon sensing danger. Patil et al. combined ultrasound studies of worms with theory to develop a model of how the movement of individual worms (or filaments) affects the collective dynamics. In particular, they found that alternating helical waves enabled both tangle formation and ultrafast untangling.

▲ 作者：SUNIL PAI, ZHANGHAO SUN, TYLER W. HUGHES, TAEWON PARK, BEN BARTLETT, IAN A. D. WILLIAMSON, MOMCHIL MINKOV, MAZIYAR MILANIZADEH, NATHNAEL ABEBE, AND DAVID A. B. MILLER

▲ 链接：

https://www.science.org/doi/10.1126/science.ade8450

▲ 摘要：

机器学习的商业应用与指数增长的能源成本相关，需要开发节能的模拟替代品。许多传统的机器学习方法使用数字反向传播进行神经网络训练，这是一项计算成本很高的任务。

作者设计了一种光子神经网络芯片，监测通过芯片每个波导段向前或向后传递的光功率，来实现高效可行的原位反向传播训练。作者提出的片上反向传播训练的原理验证实验实现，展示了机器学习在未来可能发生根本性变化的一种方式，其中大部分计算都是在光学上进行的。

▲ Abstract：

Commercial applications of machine learning (ML) are associated with exponentially increasing energy costs, requiring the development of energy-efficient analog alternatives. Many conventional ML methods use digital backpropagation for neural network training, which is a computationally expensive task. Pai et al. designed a photonic neural network chip to allow efficient and feasible in situ backpropagation training by monitoring optical power passing either forward or backward through each waveguide segment of the chip. The presented proof-of-principle experimental realization of on-chip backpropagation training demonstrates one of the ways that ML could fundamentally change in the future, with most of the computation taking place optically. 

化学Chemistry

▲ 作者：SHUO ZHANG, FANGYUAN YE, XIAOYU WANG, RUI CHEN, HUIDONG ZHANG, LIQING ZHAN, XIANYUAN JIANG, YAWEN LI, XIAOYU JI, AND YONGZHEN WU

▲ 链接：

https://www.science.org/doi/10.1126/science.adg3755

▲ 摘要：

许多用于倒钙钛矿太阳能电池的空穴传输材料要么疏水性太强，不能湿化钙钛矿前体，要么会与钙钛矿发生反应，这导致这些层之间的埋藏界面产生性能限制缺陷。

作者报道了一种两亲性分子空穴转运体，它具有亲水的氰乙烯基膦酸锚定基团和疏水的芳胺基空穴提取基团，通过润湿和钝化增强钙钛矿沉积，从而最大限度地减少了埋藏的界面缺陷。钙钛矿薄膜具有均匀性好、光致发光量子产率高、载流子寿命长的特点。封装的1平方厘米太阳能电池具有23.4%的功率转换效率和高的操作和湿热测试稳定性。

▲ Abstract：

Many of the hole-transport materials used in inverted perovskite solar cells are either too hydrophobic to wet perovskite precursors or can react with the perovskite, which causes the buried interface between these layers to develop performance-limiting defects. Zhang et al. report that an amphiphilic molecular hole transporter with a hydrophilic cyanovinyl phosphonic acid (CPA)–anchoring group and a hydrophobic arylamine–based hole-extraction group (MPA-CPA) minimized the buried interfacial defects by enhancing perovskite deposition through wetting and passivation. The perovskite films had high uniformity, high photoluminescence quantum yield, and long carrier lifetimes. Encapsulated 1-square-centimeter solar cells had a power conversion efficiency of 23.4% and high operational and damp heat test stability. 

物理学Physics

▲ 作者：HAYLEY WILLIAMS, PATRICK L. KELLY, WENLEI CHEN, GABRIEL BRAMMER, ADI ZITRIN, TOMMASO TREU, CLAUDIA SCARLATA, ANTON M. KOEKEMOER, MASAMUNE OGURI, AND LILAN YANG

▲ 链接：

https://www.science.org/doi/10.1126/science.adf5307

▲ 摘要：

宇宙的膨胀使来自遥远星系的光红移到更长的波长。候选的遥远星系可以通过成像来识别，但是确认它们的红移需要光谱学。作者利用近红外成像和光谱技术确定了一个红移9.5的星系，对应于大爆炸后大约5亿年。

在那个早期，人们对星系知之甚少。光谱中的发射线使作者能够确定该星系的一些物理特性，例如其比氦重的元素的丰度，他们发现该星系非常紧凑，恒星形成的密度很高。

▲ Abstract：

The expansion of the Universe causes the light from distant galaxies to be redshifted to longer wavelengths. Candidate distant galaxies can be identified using imaging, but confirming their redshift requires spectroscopy. Williams et al. used near-infrared imaging and spectroscopy to identify a galaxy at redshift 9.5, corresponding to about 500 million years after the Big Bang. Little is known about galaxies at that early time. Emission lines in the spectrum allowed the authors to determine some of the galaxy’s physical properties, such as its abundance of elements heavier than helium, and they found that it is very compact and has a high density of star formation.