《科學》（20181102出版）一周論文導讀

Science一周論文導讀

2018年11月2日第362卷6414期

本期封面介紹：這張由椰子構成的汽車的照片代表了商業複合材料在越來越多地使用天然材料，尤其是在汽車領域。椰子纖維（椰棕）和粉末狀椰殼可與多種聚合物結合在一起製造汽車零件，如車門包層、結構護罩和內部構件等。有關生物、混合和碳基複合材料研究和應用的更多信息，請參閱第534頁。

圖片來源：Cary和Babs Wolinsky

COVER:This whimsical photo of a coconut turned into a car represents the increasing use of natural materials incommercial composites, particularly in the automotive sector. Coconut fibers(coir) and powdered coconut shells can be combined with a variety of polymersto make car parts, including door cladding, structural guards, and internalcomponents. For more on the investigation and application of biological,hybrid, and carbon-based composite materials, see page 534.

物理學PHYSICS

Ultrafast disordering of vanadium dimers inphotoexcitedVO₂

光激二氧化釩中釩二聚體的超快無序化

作者：Simon Wall, Shan Yang, Luciana Vidas,Olivier Delaire, Mariano Trigo, et al.

鏈接：DOI:10.1126/science.aau3873

導讀：許多超快固相變被視為化學反應，它們沿著反應坐標轉換兩個不同單位晶格之間的結構，但這忽略了無序的作用。

雖然超快衍射在這一轉換過程中提供了對原子動力學的理解，但衍射本身探測的是平均單位晶格，對過渡過程中的隨機性不太敏感。

利用飛秒X射線脈衝的總散射，研究者證明了光激二氧化釩（VO₂）中的原子無序現象是這一相變機制的核心，光激後，該系統在時間尺度上探索了與單個聲子振蕩相當的大量相位空間。

這些研究結果推翻了目前對超快相變的基本認識，並為光激物質向平衡快速演化提供了新的微觀見解。

Abstract：Many ultrafast solid phase transitions aretreated as chemical reactions that transform the structures between two different unit cells along a reaction coordinate, but this neglects the role of disorder. Although ultrafast diffraction provides insights into atomic dynamics during such transformations, diffraction alone probes an averaged unit cell andis less sensitive to randomness in the transition pathway. Using totalscattering of femtosecond x-ray pulses, we show that atomic disordering inphotoexcited vanadium dioxide (VO₂) is central to the transition mechanism andthat, after photoexcitation, the system explores a large volume of phase spaceon a time scale comparable to that of a single phonon oscillation. Theser esults overturn the current understanding of an archetypal ultrafast phaset ransition and provide new microscopic insights into rapid evolution towarde quilibrium in photoexcited matter.

對二氧化釩從絕緣體到導體轉變的描述。

圖片來源：GREG STEWART/SLAC NATIONAL ACCELERATOR LABORATORY

抗流感療法ANTI-FLU THERAPY

Universal protection against influenza infection by a multidomain antibody to influenza hemagglutinin

通過流感病毒血凝素多域抗體對流感感染的普遍保護

作者：Nick S. Laursen1, Robert H. E. Friesen,Xueyong Zhu, Joost A. Kolkman, Ian A. Wilson, et al.

相關鏈接：DOI:10.1126/science.aaq0620

導讀：疫苗對於流感的控制和預防必不可少，但其有效性仍然存在若干挑戰。有些人對接種疫苗反應不佳，而且病毒變異使鎖定最佳抗原變得困難。

廣泛中和抗體是一種解決方案，但它們也有缺陷，包括對甲型和乙型流感毒株的交叉反應有限以及需要反覆注射等。

現在，研究者開發出具有廣泛效力的多領域抗體。研究人員通過鼻內注射腺病毒載體的小鼠，讓這些抗體提供了持久和連續性的保護，可抵抗各種流感毒株。

Abstract：Vaccinesare indispensable for the control and prevention of influenza, but there areseveral challenges to efficacy. Some individuals respond poorly to vaccination,and virus variation makes targeting optimal antigens difficult. Broadly neutralizing antibodies are one solution, but they have their own pitfalls,including limited cross-reactivity to both influenza A and B strains and theneed for repeated injections. Now, Laursen et al. have developed multidomain antibodies with breadth and potency. Administered intranasally to mice with anadenovirus vector, the antibodies provided durable and continuous protection from a panoply of influenza strains.

微生物群MICROBIOTA

Experimental evolution of a fungal pathogeninto a gut symbiont

真菌病原體進入腸道共生體的實驗進化

作者：Gloria Hoi Wan Tso, Jose AntonioReales-Calderon, Giulia Rancati, Norman Pavelka, et al.

相關鏈接：DOI: 10.1126/science.aat0537

導讀：腸道微生物與宿主共生，但共生的動物—微生物相互作用是如何產生的目前尚不清楚。

通過對小鼠胃腸道中機會性真菌病原菌——白色念珠菌的適應性進化，研究人員選擇了已經失去主要毒性程序及保護新宿主免受各種系統性感染的菌株。

這種保護作用獨立於適應性免疫，啟動後一天就會出現，同時依賴於增加的先天細胞因子應答，讓人聯想到「訓練過的免疫」。

因為這種微生物及其新宿主都從相互作用中獲得了一些優勢，這一實驗系統或讓直接研究控制哺乳動物和真菌間出現互利共生的進化力量成為可能。

Abstract：Gut microbes live in symbiosis with their hosts, but how mutualistic animal-microbe interactions emerge is not understood. By adaptively evolving the opportunistic fungal pathogen Candidaalbicans in the mouse gastrointestinal tract, we selected strains that not only had lost their main virulence program but also protected their new hostsa gainst a variety of systemic infections. This protection was independent of adaptive immunity, arose as early as a single day postpriming, was dependent on increased innate cytokine responses, and was thus reminiscent of 「trained immunity.」 Because both the microbe and its new host gain some advantages fromtheir interaction, this experimental system might allow direct study of the evolutionary forces that govern the emergence of mutualism between a mammal anda fungus.

納米材料NANOMATERIALS

A general synthesis approach for supported bimetallic nanoparticles via surface inorganometallic chemistry

一種利用表面無機金屬化學方法合成負載型雙金屬納米粒子的通用方法

作者：KunlunDing1, David A. Cullen, Laibao Zhang, Dongmei Cao, et al.

相關鏈接：DOI:10.1126/science.aau4414

導讀：通過組成金屬合成具有明確化學計量和親密性的超小雙金屬納米顆粒（直徑在1到3納米之間）仍是一個巨大挑戰。

研究者通過表面無機金屬化學合成了10種不同的負載型雙金屬納米粒子，其方法是通過分解和還原表面吸附的異金屬基二元絡合物鹽。

通過對二氧化硅基體上的目標陽離子和陰離子進行順序吸附，很容易得到它們。

這些負載型雙金屬納米顆粒在乙炔選擇性氫化反應中表現出增強的催化性能，清楚地顯示了組成金屬之間的協同作用。

Abstract：The synthesis of ultrasmall supported bimetallic nanoparticles (between 1 and 3nanometers in diameter) with well-defined stoichiometry and intimacy between constituent metals remains a substantial challenge. We synthesized 10 different supported bimetallic nanoparticles via surface inorganometallic chemistry by decomposing and reducing surface-adsorbed heterometallic double complex salts,which are readily obtained upon sequential adsorption of target cations andanions on a silica substrate. These supported bimetallic nanoparticles show enhanced catalytic performance in acetylene selective hydrogenation, which clearly demonstrates a synergistic effect between constituent metals.

流行病學EPIDEMIOLOGY

Predicting reservoir hosts and arthropod vectors from evolutionary signatures in RNA virus genomes

從RNA病毒基因組的進化特徵預測宿主和節肢動物載體

作者：SimonA. Babayan, Richard J. Orton, Daniel G. Streicke, et al.

相關鏈接：DOI: 10.1126/science.aap9072

導讀：確認RNA病毒的動物起源需要多年的實地和實驗室研究，這阻滯了對新發傳染病的反應。

研究者利用大量基因組和生態數據集，證明了動物宿主和節肢動物載體的存在和身份可以通過機器學習直接從病毒基因組序列中預測。

研究者演示了這些模型預測大多數人類感染的單鏈RNA病毒家族中不同病毒的流行病學的能力，包括以前難以捉摸或尚未被研究過的69種宿主或載體病毒。

這些模型利用低成本基因組測序技術的推廣，可縮短病毒發現和目標研究、監測及管理之間的時間差。

Abstract：Identifying the animal origins of RNA viruses requires years of field and laboratory studies that stall responses to emerging infectious diseases. Using large genomic and ecological datasets, we demonstrate that animal reservoirs and the existence and identity of arthropod vectors can be predicted directly from viral genome sequences via machine learning. We illustrate the ability of these models to predict the epidemiology of diverse viruses across most human-infective families of single-stranded RNA viruses, including 69 viruses with previously elusive or never-investigat edreservoirs or vectors. Models such as these, which capitalize on theproliferation of low-cost genomic sequencing, can narrow the time lag between virus discovery and targeted research, surveillance, and management.

古氣候學PALEOCLIMATOLOGY

East Asian hydroclimate modulated by theposition of the westerlies during Termination I

東亞水文氣候受西風帶位置的調節

作者：Hongbin Zhang, Michael L. Griffiths3, JohnC. H. Chiang, Youfeng Ning, Shucheng Xie, et al.

相關鏈接：DOI:10.1126/science.aat9393

導讀：洞穴化石的氧同位素記錄已經徹底改變了人們對舊石器時代東亞季風的理解，然而，科學家對它們在水文氣候變化方面所代表的意義仍存在根本分歧。

研究者報告了長江中游地區最後一次消冰期季風演化的多代理洞穴化石記錄，表明在北大西洋降溫期，儘管氧同位素記錄表明季風較弱，但中國中部較為濕潤。

研究者證明了如果按照最近的假設將這種變化解釋為梅雨期的延長和梅雨期後的縮短，那麼這種明顯的矛盾將可以解決。

模型模擬支持這一解釋，並進一步揭示了西風帶在傳遞北大西洋對東亞氣候影響方面的作用。

Abstract：Speleothem oxygen isotope recordshave revolutionized our understanding of the paleo East Asian monsoon, yet there is fundamental disagreement on what they represent in terms of the hydroclimate changes. We report a multiproxy speleothem record of monsoone volution during the last deglaciation from the middle Yangtze region, whichi ndicates a wetter central eastern China during North Atlantic coolinge pisodes, despite the oxygen isotopic record suggesting a weaker monsoon. Weshow that this apparent contradiction can be resolved if the changes are interpretedas a lengthening of the Meiyu rains and shortened post-Meiyu stage, inaccordance with a recent hypothesis. Model simulations support this interpretation and further reveal the role of the westerlies in communicating the North Atlantic influence to the East Asian climate.

神經科學NEUROSCIENCE

Efficient cortical coding of 3D posture infreely behaving rats

自由行為大鼠三維姿勢的有效皮層編碼

作者：Bartul Mimica, Benjamin A. Dunn, TuceTombaz, Jonathan R. Whitlock, et al.

相關鏈接：DOI:10.1126/science.aau2013

導讀：動物會不斷更新身體姿勢以滿足行為需求，但人們對於它所依賴的神經信號卻知之甚少。

研究者因此對自由覓食的大鼠進行了三維跟蹤，同時從其頂葉後皮層（PPC）和額葉運動皮層（M2）（對運動規劃和導航至關重要的區域）進行記錄。

這兩個區域對頭部、頸部和背部的姿勢都表現出很強的調節能力，而運動信號則不那麼佔主導地位。

大鼠頭部和背部的表徵被按照PPC和M2的構造進行了組織，更多神經元表現出較少出現的姿勢。

跨區域的同步記錄足以解碼正在進行的行為，並顯示PPC的峰值傾向於在M2之前。

PPC和M2都能通過使用空間上有組織的、能量高效的群體編碼強烈地表示姿勢。

Abstract：Animalsconstantly update their body posture to meet behavioral demands, but little isknown about the neural signals on which this depends. We therefore trackedfreely foraging rats in three dimensions while recording from the posteriorparietal cortex (PPC) and the frontal motor cortex (M2), areas critical formovement planning and navigation. Both regions showed strong tuning to postureof the head, neck, and back, but signals for movement were much less dominant.Head and back representations were organized topographically across the PPC andM2, and more neurons represented postures that occurred less often.Simultaneous recordings across areas were sufficiently robust to decode ongoingbehavior and showed that spiking in the PPC tended to precede that in M2. Boththe PPC and M2 strongly represent posture by using a spatially organized,energetically efficient population code.

量子光學QUANTUM OPTICS

Topological protection of biphoton states

雙光子態的拓撲保護

作者：AndreaBlanco-Redondo, Bryn Bell1, Dikla Oren, Benjamin J. Eggleton, Mordechai Segev

相關鏈接：DOI:10.1126/science.aau4296

導讀：多光子量子態的魯棒生成和傳播對於量子信息、計算和通信的應用至關重要。

儘管光子本質上與熱環境相隔絕，但擴展到大型量子光學器件時仍然受到散射損耗和隨機製造缺陷引起的其他誤差的限制。

最近關於拓撲相位的發現為量子系統的構建提供了途徑，可以使其免受散射和缺陷的影響。研究者通過實驗證明了雙光子態的拓撲保護，這是量子信息系統的基石。

研究者提供了在具有非平凡拓撲結構的納米光子晶格中產生的雙光子態的空間特徵和傳播常數的魯棒性的明確證據，並提出了建立量子門魯棒糾纏態的具體路徑。

Abstract：The robust generation and propagation ofmultiphoton quantum states are crucial for applications in quantum information,computing, and communications. Although photons are intrinsically well isolatedfrom the thermal environment, scaling to large quantum optical devices is stilllimited by scattering loss and other errors arising from random fabricationimperfections. The recent discoveries regarding topological phases have introduced avenues to construct quantum systems that are protected against scattering and imperfections. We experimentally demonstrate topologicalp rotection of biphoton states, the building block for quantum informations ystems. We provide clear evidence of the robustness of the spatial features and the propagation constant of biphoton states generated within ananophotonics lattice with nontrivial topology and propose a concrete path tobuild robust entangled states for quantum gates.

（晉楠編譯）

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