【MD传媒MD0076老师家访在线观看】《科学》（20260806出版）一周论文导读 为深入了解这种多功能性

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为深入了解这种多功能性，科学并在粘液分泌过程中添加无定形碳酸钙（ACC）。出版生成双唑类结构 ，周论MD传媒MD0076老师家访在线观看与约10米高度的文导便携式塔站数据形成互补。探讨了蜗牛（Cepaea nemoralis）产生的科学五种不同粘液基材料 。需要在BEV汽车的出版制造排放与减缓车辆运行排放之间进行根本性的权衡。两种亲核试剂可用于从高苄基C–X合成子构建1,周论2-双官能化加合物 ，

▲ Abstract
：

Internal combustion engine (ICE) vehicles represent the single largest source of carbon dioxide emissions for most US households. Although battery electric vehicles (BEVs) considerably reduce use-phase emissions,文导 the transition poses a fundamental life cycle optimization challenge: Is there a net climate benefit to retiring a functional ICE vehicle before its end of life? Retiring a functioning ICE vehicle incurs a fundamental trade-off between BEV manufacturing emissions and decreased vehicle operation emissions. In this study, we evaluated this trade-off across a comprehensive range of retirement scenarios and found that scrappage-and-replacement yields consistent emissions reductions across most contexts, including the retirement of new ICE vehicles. Although scrapping a functional asset remains economically prohibitive under current market conditions, these results demonstrate a major mitigation potential for policy interventions, such as enhanced scrappage subsidies, to address the emissions of an increasingly durable ICE fleet.

Decadal doubling of Siberian methane emissions due to warming-induced fires and methanogenesis

变暖催生的火灾与产甲烷作用造成西伯利亚甲烷排放十年翻倍

▲ 作者 ：Sihong Zhu, Yi Liu, Paul I. Palmer, Liang Feng, Dongxu Yang, Shangfeng Chen, et al.

▲链接：

https://www.science.org/doi/10.1126/science.aea5828

▲摘要：

北方永久冻土区储存的碳量约为大气中的两倍，直接从单官能化的科学C(sp3)–X底物生成烯烃自由基阳离子中间体 。探讨组表明地震声学数据也可用于HBL湍流分析 。出版MD传媒MD0076老师家访在线观看足以满足生物学、周论通过光氧化还原催生的文导氢原子转移（HAT）和自旋中心转移（SCS）过程，

探讨组展示了一种抗磁稳定的科学磁悬浮磁强计，包括放弃新ICE车的出版情况 。而西西伯利亚更湿润的周论条件促进了与湿地相关的排放（0.4±0.1 TgCH4·年-2）。将其与高灵敏度磁传感进行集成仍颇具挑战。两个相邻碳原子的官能化通常以烯烃或已双取代的前体为起始原料。但该结果表明
，

▲ Abstract ：

The northern permafrost region, which stores double the amount of carbon in the atmosphere, is vulnerable to accelerated warming. Methane emissions from thawing permafrost may eventually result in a climate-carbon feedback. Our analysis of atmospheric methane data shows that Siberian growing-season methane emissions have increased by 12.0 ± 1.9 teragrams of methane (TgCH4) (5% per year) over the period 2010–2023. We reveal contrasting Siberian hydrological trends linked to high-pressure systems and distinct air-sea-land interactions. Warmer, drier conditions over eastern Siberia enhance fire-related emissions (0.7 ± 0.1 TgCH4 year-2)), and wetter conditions over western Siberia promote wetland-related emissions (0.4 ± 0.1 TgCH4 year-2). Weakly nonlinear relationships between temperature maxima and emissions suggest that by 2050, higher Siberian emissions could offset about 20% of the global methane reduction required for climate targets, with eastern Siberia dominating the projected increase.

Turbulent seismoacoustic imprints during a hurricane landfall

飓风登陆过程中湍流产生的地震声印记

▲ 作者：Qing Ji, Ipshita Dey and Eric M. Dunham

▲链接：

https://www.science.org/doi/10.1126/science.adt7323

▲摘要：

飓风演变受飓风边界层（HBL）湍流的影响 ，

▲ Abstract ：

Mucus is known as a viscous fluid; yet, snails manufacture various mucus-based materials with much higher cohesion and tailored to different and even antagonistic functions, including lubrication, adhesion, protection, and defense. To gain insight into this versatility, we use a multidisciplinary approach to investigate five different mucus-based materials produced by the snail Cepaea nemoralis. Our results demonstrate that snails use collagen VI as a main structural component and add amorphous calcium carbonate (ACC) during mucus secretion. ACC functions as an ion source in wet mucus types, most likely for cross-linking, or as a mineral precursor in dry mucus types. These findings shed light on the versatility of these viscoelastic materials, which are able to switch between very different properties on the basis of calcium and protein content.

化学Chemistry

Vicinal disubstitution of alkyl C–X synthons via alkene radical cation generation

烯烃自由基阳离子生成助力烷基C–X合成子邻位双取代

▲ 作者
：Yufei Zhang, Tamal Das, Zi Xuan, Mrinmoy Das, Hammed O. Bisiriyu, Alon Nudler, Ben D. Parasch, et al.

▲链接：

https://www.science.org/doi/10.1126/science.aef0766

▲摘要：

在有机化学中 ，2010—2023年间
 ，其中东西伯利亚在预计增强中占主导地位
。提供低损耗和高隔离环境而受到广泛关注 。

湍流压力场的对流速度是这种压力-位移耦合的要紧。蜗牛可以制造出多种粘性更高的粘液基材料
，西伯利亚更高的排放量恐怕抵消全球为实现气候目标所需甲烷减排量的20%，蜗牛以VI型胶原蛋白作为主要结构组分，探讨组对大气甲烷数据的分析显示，传统上烷基C–X骨架仅限于单位点取代，

编译|未玖

物理学Physics

Levitated sensor for magnetometry in ambient environment

磁悬浮传感器助力环境条件下的磁力测量

▲ 作者 ：Wei Ji, Changhao Xu, Guofeng Qu and Dmitry Budker

▲链接 ：

https://www.science.org/doi/10.1126/science.adx1707

▲摘要
：

悬浮粒子完善作为一种高效发展的精密传感平台 ，化学和基础物理学领域的广泛应用需求
，其性能可与超导量子干涉器件和原子磁强计相媲美，更干燥的条件加剧了与火灾相关的排放（0.7±0.1 TgCH4·年-2），通过光学方式检测悬浮磁体的运动 。永久冻土融化产生的甲烷排放最终恐怕造成气候-碳反馈。在截然不同的状态之间实现转变 。

▲ Abstract：

Hurricane evolution is affected by turbulence in the hurricane boundary layer (HBL), which is typically measured using aircraft flights and towers. Through a case study of a landfalling hurricane, we show that seismoacoustic data can also be used for HBL turbulence analysis. We identified contributions of HBL turbulence in infrasound pressure and seismic displacement, validating our interpretation by combining large-eddy simulation, calibrated with meteorological data, with quasi-static elastic deformation modeling. The convection velocity of the turbulent pressure field is key to this pressure–displacement coupling. For atmospheric studies, continuous infrasound pressure serves as a proxy for 10-meter wind speed, and the inertial subrange of pressure spectra provides an estimate of the turbulent dissipation rate near the top of the surface layer at ~100 to 200 meters, complementing portable tower data at ~10 meters.

这些察觉揭示了这些粘弹性材料的多功能性
，该工作实现了将C–X骨架转化为构建邻位冗长性的格外规前体。并将其称之为“亲电穿梭”。倘若次声压力可作为10米高度风速的替代观测指标，政策干预（如提高报废补贴）具有巨大的减排潜力，验证了该解释。ACC在湿性粘液类型中可充当离子源，到2050年，

探讨组揭示了与高压完善及不同的海-气-陆相互作用相关的西伯利亚水文趋势对比
，最有恐怕用于交联；而在干性粘液类型中 ，当前室温悬浮技术主要对加速度敏感
，是否会产生净气候效益
？放弃一辆仍可正常运行的ICE汽车 ，但这一转型带来了一个根本性的生命周期优化难题：在功能性ICE汽车达到使用寿命之前将其放弃，并展现出与其他类型亲核试剂的兼容性。同时具备可在室温及地磁场环境下工作的优势 。故而
，尽管纯电动汽车（BEV）大幅缩减了使用阶段排放，即每年增强5%。电子离域和氢键溶剂分子网络共同促进了一种协同的“HAT+SCS”机制。最终实现了32飞特斯拉每平方根赫兹（32 fT/√Hz）的灵敏度
，报废尚可使用的资产在经济上仍不可行 ，通过对一次登陆飓风的案例探讨，捍卫和防御）进行定制化设计 。粘附、而压力谱的惯性子区间可估算近地面层顶部（约100至200米高度）的湍流耗散率，计算表明，

▲ Abstract：

In organic chemistry, functionalization of two adjacent carbons often starts from alkenes or already disubstituted precursors. Here, we report an exergonic activation mode that directly generates alkene radical cation intermediates from monofunctional C(sp3)–X handles through a photoredox-triggered hydrogen-atom abstraction (HAT) and spin-center shift (SCS) process. Computations show that electron delocalization and a network of hydrogen-bonding solvent molecules facilitate a concerted [HAT+SCS] mechanism. The catalytic platform was used to design a transfer of electrophilic reactivity (C–X) from one carbon to another, which we refer to as electrophilic shuttling. Thus, two nucleophiles can be used in the construction of 1,2-difunctionalization adducts from homobenzylic C–X synthons, delivering bisazole architectures and demonstrating compatibility with other nucleophile classes. We developed a suite of transformations that departs from conventional synthetic logic, for which alkyl C–X scaffolds are confined to single-site substitutions, now transforming them into nonintuitive precursors for building vicinal complexity.

地球科学Earth Science

The climate benefits of retiring a fully operational internal combustion engine vehicle

放弃功能完好内燃机汽车的气候效益

▲ 作者 ：J. Elliott Campbell and Roland Geye

▲链接：

https://www.science.org/doi/10.1126/science.adv5441

▲摘要
：

内燃机（ICE）汽车是大多数美国家庭最大的二氧化碳排放源 。因其消除机械接触及相关噪声
、

▲ Abstract 
：

Levitated particle systems have gained attention as a rapidly advancing platform for precision sensing, offering low-loss, highly isolated environments by eliminating mechanical contact and associated noise. Current room-temperature levitation techniques are primarily sensitive to acceleration, and it remains challenging to integrate them with high-sensitivity magnetic sensing. In this work, we demonstrate a diamagnetically stabilized magnetically levitated magnet magnetometer, where the motion of the magnet is detected optically. We achieved a sensitivity of 32 femtoteslas per square root of Hertz, which is adequate for a wide range of applications in biology, chemistry, and fundamental physics, matching the performance of superconducting quantum interference devices and atomic magnetometers, while offering the advantage of operating at room temperature and under Earth’s magnetic field.

材料科学Materials Science

Calcium tunes snail mucus–based materials to multiple functions

钙调控蜗牛粘液基材料的多功能性

▲ 作者：Mariella Gabler, Emeline Raguin, Ernesto Scoppola, Barbara Steigenberger, Assa Yeroslaviz, Peter Werner, et al.

▲链接 ：

https://www.science.org/doi/10.1126/science.adx7367

▲摘要
：

众所周知  ，则可充当矿物前体。且易受加速变暖的影响 。

基于该催化平台，其可以根据钙和蛋白质含量的差异，结果表明，

探讨组开发了一系列不同于传统合成逻辑的转化反应，并针对不同甚至相互对立的功能（包括润滑、有助于解决日益耐用的ICE车队所带来的排放问题。

探讨组鉴别了一系列广泛退役情景下的这种权衡 ，

温度最大值与甲烷排放之间的弱非线性关系表明
，探讨组采用多学科方法，在大气探讨领域，通常通过飞机观测和塔站测量获取。粘液是一种粘性流体；然而 ，探讨组报道了一种放能活化模式，探讨组设计了亲电反应性（C–X）从一个碳原子向另一个碳原子的转移，

尽管在当前市场条件下，察觉“报废并更换”策略在大多数情境下都能带来持续的减排效果  ，察觉东西伯利亚更温暖 、西伯利亚生长季甲烷排放增强了12.0±1.9太克甲烷（TgCH4） ，