編譯 | 李言
Science, 15 APR 2022, VOL 376, ISSUE 6590
《科學》2022年4月15日，第376卷，6590期
化學Chemistry
Allylic C–H amination cross-coupling furnishes tertiary amines by electrophilic metal catalysis
烯丙基C-H胺化交聯通過親電金屬催化生成叔胺
▲ 作者：SIRAJ Z. ALI, BRENNA G. BUDAITIS, DEVON F. A. FONTAINE et al.
▲ 連結：
https://www.science.org/doi/10.1126/science.abn8382
▲ 摘要：
末端烯烴與仲胺分子間的交叉偶聯形成複雜的叔胺（藥物合成中的一個共同基序）仍然是化學合成中的一個挑戰。在此，我們報告一種钯(II)催化的烯丙基碳-氫胺交叉偶聯反應。
它以48個環和非環仲胺（10個相關核）和34個末端烯烴（具有親電功能）為特征，合成81個叔烯丙基胺，包括12個藥物化合物和10個複雜藥物衍生物，且具有良好的區域選擇性和立體選擇性。
▲ Abstract：
Intermolecular cross-coupling of terminal olefins with secondary amines to form complex tertiary amines—a common motif in pharmaceuticals—remains a major challenge in chemical synthesis. Here, we report a palladium(II)-catalyzed allylic carbon-hydrogen amination cross-coupling using this strategy, featuring 48 cyclic and acyclic secondary amines (10 pharmaceutically relevant cores) and 34 terminal olefins (bearing electrophilic functionality) to furnish 81 tertiary allylic amines, including 12 drug compounds and 10 complex drug derivatives, with excellent regio- and stereoselectivity (>20:1 linear:branched, >20:1 E:Z).
Ambient-pressure synthesis of ethylene glycol catalyzed by C60-buffered Cu/SiO2
C60緩沖銅基催化劑實作乙二醇的常壓合成
▲ 作者：JIANWEI ZHENG, XLELE HUANG, CUN-HAO CUI et al.
▲ 連結：
https://www.science.org/doi/10.1126/science.abm9257
▲ 摘要：
乙二醇（EG）等化學品可以從乙烯或合成氣中工業化合成，但合成氣會經曆瓶頸反應且需要高壓氫氣。我們發現，以C60為代表的富勒烯可以作為銅基催化劑（Cu/ SiO2）的電子緩沖劑。
在180°~ 190°C的常壓條件下，經C60-Cu/SiO2催化，草酸二甲酯的乙二醇産率可達98±1%。在公斤級反應中，1000小時後催化劑沒有失活。這種生成乙二醇的溫和方式可以與已經工業化的環境反應相結合，從合成氣到草酸二甲酯的中間産物。
▲ Abstract：
Bulk chemicals such as ethylene glycol (EG) can be industrially synthesized from either ethylene or syngas, but the latter undergoes a bottleneck reaction and requires high hydrogen pressures. We show that fullerene (exemplified by C60) can act as an electron buffer for a copper-silica catalyst (Cu/SiO2). Hydrogenation of dimethyl oxalate over a C60-Cu/SiO2 catalyst at ambient pressure and temperatures of 180° to 190°C had an EG yield of up to 98 ± 1%. In a kilogram-scale reaction, no deactivation of the catalyst was seen after 1000 hours. This mild route for the final step toward EG can be combined with the already-industrialized ambient reaction from syngas to the intermediate of dimethyl oxalate.
Amplification of light within aerosol particles accelerates in-particle photochemistry
光在氣溶膠粒子内被放大加速了粒子内的光化學過程
▲ 作者：PABLO CORRAL ARROYO, GRÉGORY DAVID, PETER A. ALPERT et al.
▲ 連結：
https://www.science.org/doi/10.1126/science.abm7915
▲ 摘要：
光密封（OC）結構光場和放大大氣氣溶膠粒子内部的光強度，對氣溶膠的光驅化學過程具有重要影響。雖然已經理論化了，但OC誘導的空間結構迄今為止還沒有在實驗中觀察到。
在此，x射線光譜顯微鏡成像與模組化結合，為光活性粒子内部OC誘導的模式提供了直接證據。單一的鐵(III) -檸檬酸粒子被探測使用鐵氧化狀态作為光化學标記。
基于這些結果，我們預測大多數種類的氣溶膠粒子光化學反應的總體加速為2到3倍。自由氣溶膠粒子的旋轉和粒子内分子的輸運通常會加速光化學過程。考慮到OC效應的普遍存在，大氣模型應考慮其對氣溶膠粒子光化學過程的影響。
▲ Abstract：
Optical confinement (OC) structures the optical field and amplifies light intensity inside atmospheric aerosol particles, with major consequences for sunlight-driven aerosol chemistry. Although theorized, the OC-induced spatial structuring has so far defied experimental observation. Here, x-ray spectromicroscopic imaging complemented by modeling provides direct evidence for OC-induced patterning inside photoactive particles. Single iron(III)–citrate particles were probed using the iron oxidation state as a photochemical marker. Based on these results, we predict an overall acceleration of photochemical reactions by a factor of two to three for most classes of atmospheric aerosol particles. Rotation of free aerosol particles and intraparticle molecular transport generally accelerate the photochemistry. Given the prevalence of OC effects, their influence on aerosol particle photochemistry should be considered by atmospheric models.
材料科學Materials Science
Volumetric additive manufacturing of silica glass with microscale computed axial lithography
微尺度計算軸向光刻上的矽玻璃體積增材制造
▲ 作者：JOSEPH T. TOOMBS, MANUEL LUITZ, CAITLYN C. COOK et al.
▲ 連結：
https://www.science.org/doi/10.1126/science.abm6459
▲ 摘要：
從消費品的微光學到用于化學合成和生物分析的微流體系統，玻璃作為制造複雜的微觀幾何形狀的材料越來越受歡迎。随着玻璃尺寸、幾何形狀、表面粗糙度和機械強度要求的發展，傳統的加工方法受到了挑戰。
我們介紹了熔融二氧化矽元件的微尺度軸向計算光刻技術（micro-CAL），即對随後燒結的光緻聚合物—二氧化矽納米複合材料進行層析成像。我們制作了内徑為150微米的三維微流體，表面粗糙度為6納米的自由曲面微光學元件，以及最小特征尺寸為50微米的複雜高強度桁架和晶格結構。
micro-CAL作為一種高速的數字化輕制造技術，可以加工高固含量、高幾何自由度的納米複合材料，實作了新的器件結構和應用。
▲ Abstract：
Glass is increasingly desired as a material for manufacturing complex microscopic geometries, from the micro-optics in compact consumer products to microfluidic systems for chemical synthesis and biological analyses. As the size, geometric, surface roughness, and mechanical strength requirements of glass evolve, conventional processing methods are challenged. We introduce microscale computed axial lithography (micro-CAL) of fused silica components, by tomographically illuminating a photopolymer-silica nanocomposite that is then sintered. We fabricated three-dimensional microfluidics with internal diameters of 150 micrometers, free-form micro-optical elements with a surface roughness of 6 nanometers, and complex high-strength trusses and lattice structures with minimum feature sizes of 50 micrometers. As a high-speed, layer-free digital light manufacturing process, micro-CAL can process nanocomposites with high solids content and high geometric freedom, enabling new device structures and applications.
地球科學Geoscience
Citizen seismology helps decipher the 2021 Haiti earthquake
公民地震學有助于破譯2021年海地地震
▲ 作者：E. CALAIS, S. SYMITHET. MONFRET, B. DELOUIS et al.
▲ 連結：
https://www.science.org/doi/10.1126/science.abn1045
▲ 摘要：
發生于2021年8月14日的海地尼普斯省7.2級地震，與破壞性的2010年7.0級地震發生在同一斷層帶，但由于救援受不安全因素的限制以及國家網絡中的正常地震儀無法工作，地震依然襲擊了該國。
但是，2019年安裝的民用地震儀網絡提供了對快速了解主震機理和監測其餘震序列至關重要的近場資料。他們的實時資料定義了兩個餘震群，并與傳統地震和大地測量資料反演得到的兩個同震滑動區域相吻合。
通過将機器學習應用于離主震最近的民用地震儀的資料，使我們能夠像使用網絡衍生的目錄一樣準确地預測餘震。這顯示了公民科學在幫助我們了解大地震方面的作用。
▲ Abstract：
On 14 August 2021, the moment magnitude (Mw) 7.2 Nippes earthquake in Haiti occurred within the same fault zone as its devastating 2010 Mw 7.0 predecessor, but struck the country when field access was limited by insecurity and conventional seismometers from the national network were inoperative. A network of citizen seismometers installed in 2019 provided near-field data critical to rapidly understand the mechanism of the mainshock and monitor its aftershock sequence. Their real-time data defined two aftershock clusters that coincide with two areas of coseismic slip derived from inversions of conventional seismological and geodetic data. Machine learning applied to data from the citizen seismometer closest to the mainshock allows us to forecast aftershocks as accurately as with the network-derived catalog. This shows the utility of citizen science contributing to our understanding of a major earthquake.
神經科學Neuroscience
Compartmentalized dendritic plasticity during associative learning
聯想學習中區分樹突可塑性
▲ 作者：SIMON D’AQUIN, ANDRAS SZONYI, MATHIAS MAHN et al.
▲ 連結：
https://www.science.org/doi/10.1126/science.abf7052
▲ 摘要：
依賴經驗的行為變化是由大腦回路中的長期功能修改所調節的。突觸輸入的活動依賴性可塑性是一個主要的細胞基礎過程。
雖然我們對體外的突觸和樹突可塑性有了詳細的了解，但對活動生物的活性樹突功能和可塑性依然知之甚少。利用腦深部雙光子鈣成像，我們調查了經典恐懼條件反射如何在杏仁核主要神經元中産生感覺反應。
恐懼條件反射誘導樹突和軀體的差異可塑性受室特異性抑制的調節。我們的研究結果表明，學習誘導的可塑性可以在體和樹突之間解耦合，反映了不同的突觸和微電路水準機制，增加了杏仁核回路的計算能力。
▲ Abstract：
Experience-dependent changes in behavior are mediated by long-term functional modifications in brain circuits. Activity-dependent plasticity of synaptic input is a major underlying cellular process. Although we have a detailed understanding of synaptic and dendritic plasticity in vitro, little is known about the functional and plastic properties of active dendrites in behaving animals. Using deep brain two-photon Ca2+ imaging, we investigated how sensory responses in amygdala principal neurons develop upon classical fear conditioning, a form of associative learning. Fear conditioning induced differential plasticity in dendrites and somas regulated by compartment-specific inhibition. Our results indicate that learning-induced plasticity can be uncoupled between soma and dendrites, reflecting distinct synaptic and microcircuit-level mechanisms that increase the computational capacity of amygdala circuits.