封面圖展示了通過多通道電子顯微鏡揭示出的反滲透膜三維納米結構 （圖中金色部分），以及為了提高性能而控制其聚合物質量分布的需求。納米分辨率級別的容積重建被用作顯示流線的水流模擬輸入（灰色部分;如圖所示，水流自上而下流動）。為了實現(xiàn)最大化水產(chǎn)量，關鍵就是最大限度地減少“死區(qū)”，從而在整個薄膜上獲取更均勻的密度。

Multimodal electronmicroscopy reveals the threedimensional nanostructure （gold）of reverseosmosis membranes.as well as the need to controltheir polymer mass distributionfor improved performance.Volume reconstructions withnanometer resolution are used asinputs for water flow simulationsthat reveal streamLines （gray：here. water flows from topto bottom）. Minimizing lideadzonesll， thereby achieving amore uniform density throughoutthe membranes. is key tomaxmizing water production.

封面圖上展示的是一個缺乏糖基化的小鼠精子在繞圈游動。糖基化是微管蛋白的一種翻譯后修飾，主要存在于纖毛和鞭毛中，它有助于協(xié)調纖毛軸動力蛋白馬達，為鞭毛拍擊提供動力。缺乏糖基化會導致異常的鞭毛拍擊，從而導致精子繞圈游動而不是直線行進。這種情況的發(fā)生會進一步嚴重影響雄性的生育能力。

A mouse sperm lackingglycylation swlms in circles.Glycylation is a posttranslationalmodification of tubulin that ispredominately found in cilia andflagella， where it contributes tOcoordinating axonemal dyneinmotors that power the flagellarbeating. Lack of glycylationcauses an abnormal flageLlar beatand results iIl circular instead ofstraight sperm swlmming. This inturn severelv affects male fertility.

封面圖展示的是位于波多黎各阿雷西博天文臺的射電望遠鏡，其寬度達到305米，這張俯拍圖片拍攝于上世紀80年代末。近60年來，該望遠鏡一直處于天文學、行星科學及大氣科學的領先地位。2020年12月1日，其重型儀器平臺由于懸索失效而倒塌損壞。研究人員在倡議重建的同時，也在調查事故發(fā)生的原因。

The 30s-meterwide radiodish of Puerto Rico S AreciboObservatory. as seen from abovein the late 1980s. For nearly 60years. the telescope stood at thevanguard of astronomy， planetaryscience. and atmospheric science.On l December 2020， itS heavyinstrument platform collapsedafter the failure of its suspensioncables. Researchers are examiningthe causes of the disaster even asthey advocate for rebuilding.

封面圖上展示的是一條莫桑比克射毒眼鏡蛇，某些眼鏡蛇會將噴吐毒液作為一種有效的遠程防御機制。毒蛇所噴射毒液的3種來源與毒液成分的聚合型變化一致，這使得毒液能夠通過增強受體的疼痛發(fā)揮防御功能。這些發(fā)現(xiàn)強調了進化過程可以將復雜的適應性引導到可重復的路徑上。

Some cobras. such asthis Mozambique spitting cobra （Najamossambica）. use venom spitting as an effective long-range defense mechanism. The three origins of venom spitting in snakes coincide with convergent changes to venom composition，

aLlowing venomto serve a defensive function by producing enhanced pain inthe recipient. These findings emphasize that evolution canfunnel complex adaptations down repeatable pathways.

（陶陶編譯）