編譯 | 未玖
Science, 5 AUG 2022, VOL 377, ISSUE 6606
《科學》2022年8月5日，第377卷，6606期
物理學Physics
Observation of a continuous time crystal
作者：：PHATTHAMON KONGKHAMBUT, JIM SKULTE, LUDWIG MATHEY, JAYSON G. COSME, ANDREAS HEMMERICH, AND HANS KESSLE
鏈接：
https://www.science.org/doi/10.1126/science.abo3382
摘要：
時間晶體分為離散時間晶體或連續(xù)時間晶體，這取決于其是否自發(fā)打破離散時間平移對稱性或連續(xù)時間平移對稱性。雖然離散時間晶體已在周期驅動系統(tǒng)中進行了廣泛研究，但連續(xù)時間晶體的實驗實現(xiàn)仍懸而未決。
研究組報道了在連續(xù)泵浦的耗散原子腔系統(tǒng)中觀察到一個極限循環(huán)相位，其特征是內腔光子數(shù)中的涌現(xiàn)振蕩。振蕩相位對于不同的實現(xiàn)是隨機的，因此，這種動態(tài)多體狀態(tài)自發(fā)打破了連續(xù)時間平移對稱性。
此外，觀測到的極限循環(huán)對時間擾動具有魯棒性，因此證明了連續(xù)時間晶體的實現(xiàn)。
Abstract：
Time crystals are classified as discrete or continuous depending on whether they spontaneously break discrete or continuous time translation symmetry. Although discrete time crystals have been extensively studied in periodically driven systems, the experimental realization of a continuous time crystal is still pending. We report the observation of a limit cycle phase in a continuously pumped dissipative atom-cavity system that is characterized by emergent oscillations in the intracavity photon number. The phase of the oscillation was found to be random for different realizations, and hence, this dynamical many-body state breaks continuous time translation symmetry spontaneously. Furthermore, the observed limit cycles are robust against temporal perturbations and therefore demonstrate the realization of a continuous time crystal.
材料科學Materials Science
Synchronous assembly of chiral skeletal single-crystalline microvessels
手性骨架單晶微容器的同步組裝
作者：OSAMU OKI, HIROSHI YAMAGISHI, YASUHIRO MORISAKI, RYO INOUE, KANA OGAWA, NANAMI MIKI, ET AL.
鏈接：
https://www.science.org/doi/10.1126/science.abm9596
摘要：
骨架或凹型多面體晶體在各種合成過程和自然環(huán)境中普遍存在。然而，由于它們具有高動力學生長特性，其形態(tài)、大小和取向很難控制。
研究組報道了一種從平面手性雙層分子實現(xiàn)同步、單軸和分步生長微米尺度骨架單晶的方法。在將加熱的乙醇溶液滴注到石英襯底上后，分子在襯底的寬廣面積內單軸同步地自發(fā)組裝成直立的容器形單晶，具有小尺寸的多分散性。
晶體邊緣即使在消耗分子后仍然活躍，且通過連續(xù)分子增加恢復立體選擇性生長。生成的形態(tài)可包裝為多環(huán)芳烴類的微結構，并表現(xiàn)為一個微觀容器。
Abstract：
Skeletal or concave polyhedral crystals appear in a variety of synthetic processes and natural environments. However, their morphology, size, and orientation are difficult to control because of their highly kinetic growth character. We report a methodology to achieve synchronous, uniaxial, and stepwise growth of micrometer-scale skeletal single crystals from planar-chiral double-decker molecules. Upon drop-casting of a heated ethanol solution onto a quartz substrate, the molecules spontaneously assemble into standing vessel-shaped single crystals uniaxially and synchronously over the wide area of the substrate, with small size polydispersity. The crystal edge is active even after consumption of the molecules and resumes stereoselective growth with successive feeding. The resultant morphology can be packed into polycyclic aromatic hydrocarbon–like microarchitectures and behaves as a microscopic container.
化學Chemistry
Carbene reactivity from alkyl and aryl aldehydes
烷基和芳基醛的卡賓反應性
作者：LUMIN ZHANG, BETHANY M. DEMUYNCK, ALYSON N. PANEQUE, JOY E. RUTHERFORD, AND DAVID A. NAGIB
鏈接：
https://www.science.org/doi/10.1126/science.abo6443
摘要：
卡賓是高度賦能的活性中間體，有助于促進各種各樣難以實現(xiàn)的化學反應，包括形成小環(huán)和插入到強σ鍵。為了獲得這種有價值的反應性，通常使用具有高熵或高焓驅動力的試劑，包括爆炸性（重氮）或不穩(wěn)定（偕二鹵）化合物。
研究組報道了常見的醛很容易（通過穩(wěn)定的α-酰氧基鹵化物中間體）轉化為電子多樣性（供體或中性）卡賓，以促進>10種的反應類別。該策略使烷基、芳基和甲酰基醛的不穩(wěn)定卡賓通過鋅類卡賓發(fā)生安全反應。
地球上豐富的金屬鹽[氯化鐵（II）（FeCl2）、氯化鈷（II）（CoCl2）、氯化銅（I）（CuCl）]是這些化學選擇性卡賓加成至σ和π鍵的有效催化劑。
Abstract：
Carbenes are highly enabling reactive intermediates that facilitate a perse range of otherwise inaccessible chemistry, including small-ring formation and insertion into strong σ bonds. To access such valuable reactivity, reagents with high entropic or enthalpic driving forces are often used, including explosive (diazo) or unstable (gem-dihalo) compounds. Here, we report that common aldehydes are readily converted (via stable α-acyloxy halide intermediates) to electronically perse (donor or neutral) carbenes to facilitate >10 reaction classes. This strategy enables safe reactivity of nonstabilized carbenes from alkyl, aryl, and formyl aldehydes via zinc carbenoids. Earth-abundant metal salts [iron(II) chloride (FeCl2), cobalt(II) chloride (CoCl2), copper(I) chloride (CuCl)] are effective catalysts for these chemoselective carbene additions to σ and π bonds.
地球科學Earth Science
Changes in North Atlantic deep-water oxygenation across the Middle Pleistocene Transition
作者：NICOLA C. THOMAS, HAROLD J. BRADBURY, AND DAVID A. HODELL
鏈接：
https://www.science.org/doi/10.1126/science.abj7761
摘要：
海洋深水氧濃度和大氣二氧化碳（pCO2）濃度通過有機碳再礦化和作為溶解無機碳儲存在深海中而內在聯(lián)系在一起。
研究組利用表棲和內棲底棲有孔蟲物種之間的碳同位素梯度作為古氧的替代，對過去150萬年來北大西洋深海氧濃度的相對變化進行了高分辨率重建。
他們報道了約96萬至90萬年前冰川大西洋深水氧合作用的顯著減少（>40微摩爾/千克），這與大陸冰量增加和海洋溫鹽環(huán)流的重大變化相吻合。
古氧結果支持了一種假設，即在中更新世過渡期，深水氧濃度降低，呼吸碳儲存增加，冰川pCO2減少。
Abstract：
The oxygen concentrations of oceanic deep-water and atmospheric carbon dioxide (pCO2) are intrinsically linked through organic carbon remineralization and storage as dissolved inorganic carbon in the deep sea. We present a high-resolution reconstruction of relative changes in oxygen concentration in the deep North Atlantic for the past 1.5 million years using the carbon isotope gradient between epifaunal and infaunal benthic foraminifera species as a proxy for paleo-oxygen. We report a significant (>40 micromole per kilogram) reduction in glacial Atlantic deep-water oxygenation at ~960 thousand to 900 thousand years ago that coincided with increased continental ice volume and a major change in ocean thermohaline circulation. Paleo-oxygen results support a scenario of decreasing deep-water oxygen concentrations, increased respired carbon storage, and a reduction in glacial pCO2 across the Middle Pleistocene Transition.
醫(yī)學Medicine
Pathogenic variants damage cell composition and single cell transcription in cardiomyopathies
心肌病中致病性變異損害細胞組成和單細胞轉錄
作者：DANIEL REICHART, ERIC L. LINDBERG, HENRIKE MAATZ, ANTONIO M. A. MIRANDA, ANISSA VIVEIROS, NIKOLAY SHVETSOV, ET AL.
鏈接：
https://www.science.org/doi/10.1126/science.abo1984
摘要：
導致擴張型心肌病（DCM）和心律失常性心肌?。ˋCM）的致病基因變異通過未知機制引發(fā)心力衰竭發(fā)展的高風險。
使用單核RNA測序，研究組對18個對照和61個伴DCM和ACM基因致病性變異或特發(fā)性疾病的衰竭、非缺血性人類心臟的88萬個核轉錄組進行了表征。他們對心室細胞譜系和轉錄狀態(tài)進行了基因型分層分析。
獲得的DCM和ACM心室細胞圖譜顯示了不同的右心室和左心室反應，突出了基因型相關通路、細胞間相互作用和單細胞分辨率下的差異基因表達。
總之，這些數(shù)據(jù)闡明了人類心力衰竭的共同和獨特的細胞和分子結構，并提出了候選治療靶點。
Abstract：
Pathogenic variants in genes that cause dilated cardiomyopathy (DCM) and arrhythmogenic cardiomyopathy (ACM) convey high risks for the development of heart failure through unknown mechanisms. Using single-nucleus RNA sequencing, we characterized the transcriptome of 880,000 nuclei from 18 control and 61 failing, nonischemic human hearts with pathogenic variants in DCM and ACM genes or idiopathic disease. We performed genotype-stratified analyses of the ventricular cell lineages and transcriptional states. The resultant DCM and ACM ventricular cell atlas demonstrated distinct right and left ventricular responses, highlighting genotype-associated pathways, intercellular interactions, and differential gene expression at single-cell resolution. Together, these data illuminate both shared and distinct cellular and molecular architectures of human heart failure and suggest candidate therapeutic targets.
公共衛(wèi)生Public Health
Mosaic RBD nanoparticles protect against challenge by perse sarbecoviruses in animal models
作者：ALEXANDER A. COHEN, NEELTJE VAN DOREMALEN, ALLISON J. GREANEY, HANNE ANDERSEN, ANKUR SHARMA, TYLER N. STARR, ET AL.
鏈接：
https://www.science.org/doi/10.1126/science.abq0839
摘要：
為了對抗未來威脅全球健康的SARS-CoV-2變異株和SARS樣β-冠狀病毒（沙貝病毒）外溢，研究組設計了馬賽克納米顆粒，其呈現(xiàn)隨機排列的沙貝病毒尖峰受體結合域（RBD），以誘導針對保守且相對封閉（而非可變、免疫顯性和暴露）表位的抗體。
研究組比較了小鼠和獼猴中由馬賽克-8（SARS-CoV-2和七種動物沙貝病毒）和同型（僅SARS-CoV-2）RBD納米顆粒誘導的免疫反應，并觀察到馬賽克-8對錯配（非納米顆粒）毒株（包括SARS-CoV和動物沙貝病毒）誘導的反應更強。
馬賽克-8免疫對SARS-CoV-2變異株（包括奧密克戎）具有同等的中和作用，并能抵御SARS-CoV-2和SARS-CoV攻擊，而同型SARS-CoV-2免疫僅能抵御SARS-CoV-2攻擊。表位圖譜顯示馬賽克-8免疫后保守表位的靶向性增加。
總之，這些結果表明馬賽克-8 RBD納米顆粒可以防止SARS-CoV-2變異株和未來的沙貝病毒溢出。
Abstract：
To combat future severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants and spillovers of SARS-like betacoronaviruses (sarbecoviruses) threatening global health, we designed mosaic nanoparticles that present randomly arranged sarbecovirus spike receptor-binding domains (RBDs) to elicit antibodies against epitopes that are conserved and relatively occluded rather than variable, immunodominant, and exposed. We compared immune responses elicited by mosaic-8 (SARS-CoV-2 and seven animal sarbecoviruses) and homotypic (only SARS-CoV-2) RBD nanoparticles in mice and macaques and observed stronger responses elicited by mosaic-8 to mismatched (not on nanoparticles) strains, including SARS-CoV and animal sarbecoviruses. Mosaic-8 immunization showed equivalent neutralization of SARS-CoV-2 variants, including Omicrons, and protected from SARS-CoV-2 and SARS-CoV challenges, whereas homotypic SARS-CoV-2 immunization protected only from SARS-CoV-2 challenge. Epitope mapping demonstrated increased targeting of conserved epitopes after mosaic-8 immunization. Together, these results suggest that mosaic-8 RBD nanoparticles could protect against SARS-CoV-2 variants and future sarbecovirus spillovers.
