作者:未玖 来源:科学网微信公众号 发布时间:2023/8/6 20:51:19
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《科学》(20230804出版)一周论文导读

 

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Science, 4 AUG 2023, VOL 381, ISSUE 6657

《科学》2023年8月4日,第381卷,6657期

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材料科学Materials Science

Intrinsically elastic polymer ferroelectric by precise slight cross-linking

通过精确微交联实现本征弹性铁电聚合物

▲ 作者:Liang Gao, Ben-Lin Hu, Linping Wang, Jinwei Cao, Ri He, Fengyuan Zhang, et al.

▲ 链接:

https://www.science.org/doi/full/10.1126/science.adh2509

▲ 摘要:

铁电体是现代世界不可分割的组成部分,在电学、电子学和生物医学中具有重要意义。然而,铁电体在新兴可穿戴电子产品中的应用受到非弹性变形的限制。

研究组通过塑性铁电聚合物的微交联,将铁电响应和弹性回弹结合到一种材料中,开发了本征弹性铁电体。精确的微交联可实现结晶性和回弹性之间的复杂平衡。

因此,研究组制备了在高达70%应变的机械变形下仍具有稳定铁电响应的弹性铁电体。这种弹性铁电体有望应用于可穿戴电子产品,例如弹性铁电传感器、信息存储和能量转换。

▲ Abstract:

Ferroelectrics are an integral component of the modern world and are of importance in electrics, electronics, and biomedicine. However, their usage in emerging wearable electronics is limited by inelastic deformation. We developed intrinsically elastic ferroelectrics by combining ferroelectric response and elastic resilience into one material by slight cross-linking of plastic ferroelectric polymers. The precise slight cross-linking can realize the complex balance between crystallinity and resilience. Thus, we obtained an elastic ferroelectric with a stable ferroelectric response under mechanical deformation up to 70% strain. This elastic ferroelectric exerts potentials in applications related to wearable electronics, such as elastic ferroelectric sensors, information storage, and energy transduction.

A stable rhombohedral phase in ferroelectric Hf(Zr)1+xO2capacitor with ultralow coercive field

具有超低矫顽场铁电Hf(Zr)1+xO2电容器中的稳定菱形相

▲ 作者:Yuan Wang, Lei Tao, Roger Guzman, Qing Luo, Wu Zhou, Yang Yang, et al.

▲ 链接:

https://www.science.org/doi/full/10.1126/science.adf6137

▲ 摘要:

基于氧化铪的铁电材料因其能够集成到硅电子器件中,是下一代纳米级器件颇有潜力的候选者。然而,萤石结构氧化物铁电器件固有的高矫顽场导致其工作电压不兼容,耐久性能受限。

研究组发现了一种富含铪-锆[Hf(Zr)]的互补金属氧化物半导体(CMOS)兼容菱形铁电体Hf(Zr)1+xO2材料。X射线衍射结合扫描透射电镜显示,过量的Hf(Zr)原子嵌入在空心位点内,嵌入的原子扩展了晶格,增加了面内和面外应力,从而稳定了菱形相(r相)及其铁电性质。

该铁电器件基于r相Hf(Zr)1+xO2,具有超低的矫顽场(约0.65兆伏/厘米),此外还在饱和极化下实现了超过1012次循环的高耐久性。该材料的发现或有助于实现低成本和长寿命的存储芯片。

▲ Abstract:

Hafnium oxide–based ferroelectric materials are promising candidates for next-generation nanoscale devices because of their ability to integrate into silicon electronics. However, the intrinsic high coercive field of the fluorite-structure oxide ferroelectric devices leads to incompatible operating voltage and limited endurance performance. We discovered a complementary metal-oxide semiconductor (CMOS)–compatible rhombohedral ferroelectric Hf(Zr)1+xO2material rich in hafnium-zirconium [Hf(Zr)]. X-ray diffraction combined with scanning transmission electron microscopy reveals that the excess Hf(Zr) atoms intercalate within the hollow sites. We found that the intercalated atoms expand the lattice and increase the in-plane and out-of-plane stresses, which stabilize both the rhombohedral phase (r-phase) and its ferroelectric properties. Our ferroelectric devices, which are based on the r-phase Hf(Zr)1+xO2, exhibit an ultralow coercive field (~0.65 megavolts per centimeter). Moreover, we achieved a high endurance of more than 1012cycles at saturation polarization. This material discovery may help to realize low-cost and long-life memory chips.

化学Chemistry

Mechanistic snapshots of rhodium-catalyzed acylnitrene transfer reactions

铑催化酰氮烯转移反应的机理瞬拍

▲ 作者:Hoimin Jung, Jeonguk Kweon, Jong-Min Suh, Mi Hee Lim, Dongwook Kim & Sukbok Chang

▲ 链接:

https://www.science.org/doi/full/10.1126/science.adh8753

▲ 摘要:

铑(Rh)酰氮烯配合物广泛涉及催化C-H酰胺化反应,但尚未能进行分离和结构表征。

为了克服这一挑战,研究组设计了一种带有双齿二恶唑酮配体的发色八面体Rh配合物,其中光诱导金属到配体的电荷转移引发催化C-H酰胺化。对Rh-二恶唑酮配合物的X射线光晶体学分析阐明了目标Rh-酰氮宾结构,并提供了单线态氮宾物种主导酰氨基转移反应的有力证据。

研究组还监测了亲核试剂与原位生成的Rh-酰氮宾的结晶反应,为捕获氮宾转移的机理瞬拍提供了一个晶体学上可追踪的反应体系。

▲ Abstract:

Rhodium (Rh) acylnitrene complexes are widely implicated in catalytic C–H amidation reactions but have eluded isolation and structural characterization. To overcome this challenge, we designed a chromophoric octahedral Rh complex with a bidentate dioxazolone ligand, in which photoinduced metal-to-ligand charge transfer initiates catalytic C–H amidation. X-ray photocrystallographic analysis of the Rh-dioxazolone complex allowed structural elucidation of the targeted Rh-acylnitrenoid and provided firm evidence that the singlet nitrenoid species is primarily responsible for acylamino transfer reactions. We also monitored in crystallo reaction of a nucleophile with the in situ–generated Rh-acylnitrenoid, which provided a crystallographically traceable reaction system to capture mechanistic snapshots of nitrenoid transfer.

Photosensitized O2 enables intermolecular alkene cyclopropanation by active methylene compounds

光敏O2通过活性亚甲基化合物实现分子间烯烃环丙烷化

▲ 作者:Dhruba P. Poudel, Amrit Pokhrel, Raj Kumar Tak, Majji Shankar & Ramesh Giri

▲ 链接:

https://www.science.org/doi/full/10.1126/science.adg3209

▲ 摘要:

环丙烷是许多临床前、临床和商业药物以及天然产品的关键特征。最多产的合成技术是烯烃与重氮烷烃的金属催化反应,重氮烷是一种高能试剂,需要严格的安全预防措施。发现可替代的无害试剂仍是一项持续挑战。

研究组报道了一种简单、光氧化还原催化的未活化烯烃与活性亚甲基化合物的分子间环丙烷化反应。在空气或氧气(O2)下的中性溶剂中,该反应借由蓝色发光二极管光激发的光氧化还原催化剂和碘辅助催化剂(作为分子碘添加或由烷基碘化物原位生成)进行。

机理研究表明,无论活性亚甲基化合物加成至烯烃还是闭环反应,光敏O2在碳中心自由基的生成中都起着至关重要的作用。

▲ Abstract:

Cyclopropanes are key features in many preclinical, clinical, and commercial drugs, as well as natural products. The most prolific technique for their synthesis is the metal-catalyzed reaction of an alkene with a diazoalkane, a highly energetic reagent requiring stringent safety precautions. Discovery of alternative innocuous reagents remains an ongoing challenge. Herein, we report a simple photoredox-catalyzed intermolecular cyclopropanation of unactivated alkenes with active methylene compounds. The reaction proceeds in neutral solvent under air or dioxygen (O2) with a photoredox catalyst excited by blue light-emitting diode light and an iodine co-catalyst that is either added as molecular iodine or generated in situ from alkyl iodides. Mechanistic investigations indicate that photosensitized O2plays a vital role in the generation of carbon-centered radicals for both the addition of active methylene compounds to alkenes and the ring closure.

地球科学Earth Science

Tremor signals during fluid injection are generated by fault slip

流体注入过程中的震颤信号由断层滑动产生

▲ 作者:Shankho Niyogi, Abhijit Ghosh, Abhash Kumar & Richard W. Hammack

▲ 链接:

https://www.science.org/doi/full/10.1126/science.adh1331

▲ 摘要:

地震震颤信号也被称为长周期、长持续时间信号,已在几个为加强油气勘探而进行流体注入的地方被报道。然而,人们对这些信号的来源仍知之甚少。

研究组分析了堪萨斯州惠灵顿油田的地震震颤信号,在二氧化碳注入项目中使用了地震阵列。他们表明,这些信号是在二氧化碳注入时在地表以下产生的,具有类似于在冰川和火山环境中观察到的独特光谱特征。

震源位于注入点附近,并与先前存在的断层对齐。模拟结果表明,这种地震是由断层上的摩擦滑动产生的。这些观测结果可能揭示了一种重要的变形模式,有助于研究相关应力、地震活动性和触发,以及在所有流体(包括超临界二氧化碳)注入操作期间跟踪断层活动。

▲ Abstract:

Seismic tremor signals, also known as long-period, long-duration signals, have been reported in several locations where fluid injection for enhanced oil and gas exploration is taking place. However, the origin of these signals remains poorly constrained. We studied seismic tremor signals in Wellington Field, Kansas, using a seismic array during a carbon dioxide injection program. We show that these signals are generated below the surface during the time of carbon dioxide injection. They have a distinct spectral signature, similar to those observed in glacial and volcanic environments. The tremor sources are located near the injection site and aligned with preexisting faults. Modeling results imply that such tremors are generated by frictional slip on fault. These observations may reveal an important deformation mode, which is useful for studying associated stress, seismicity, and triggering, as well as for tracking fault activities during injection operations of all fluids, including supercritical carbon dioxide.

空间组学Spatial Omics

The dawn of spatial omics

空间组学的曙光

▲ 作者:Dario Bressan, Giorgia Battistoni & Gregory J. Hannon

▲ 链接:

https://www.science.org/doi/full/10.1126/science.abq4964

▲ 摘要:

空间组学被广泛认为是生命科学的新前沿。这个概念涵盖一系列广泛的技术,有望改观生物学的许多领域,并最终通过同时测量物理组织结构和分子特征来彻底改变病理学。

尽管空间组学在过去5年里已趋成熟,但它仍面临着一些发展缺陷:进入壁垒、稳健性、实验设计和分析的最佳实践不明确,以及缺乏标准化。

在该文中,研究组提出了不同类型空间组学技术的系统目录;强调其原理、强项和局限性;并就这一非常强大但仍难以驾驭的领域面临的最大挑战给出了一些观点和建议。

▲ Abstract:

Spatial omics has been widely heralded as the new frontier in life sciences. This term encompasses a wide range of techniques that promise to transform many areas of biology and eventually revolutionize pathology by measuring physical tissue structure and molecular characteristics at the same time. Although the field came of age in the past 5 years, it still suffers from some growing pains: barriers to entry, robustness, unclear best practices for experimental design and analysis, and lack of standardization. In this Review, we present a systematic catalog of the different families of spatial omics technologies; highlight their principles, power, and limitations; and give some perspective and suggestions on the biggest challenges that lay ahead in this incredibly powerful—but still hard to navigate—landscape.

 
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