《科學》（20231208出版）一周論文導讀

原文地址：http://news.sciencenet.cn/htmlnews/2023/12/513970.shtm

Science, 8 DEC 2023, VOL 382, ISSUE 6675

《科學》2023年12月8日，第382卷，6675期

天文學Astronomy

Element abundance patterns in stars indicate fission of nuclei heavier than uranium

恒星中的元素豐度模式表明比鈾重的原子會發生核裂變

▲ 作者：Ian U. Roederer, Nicole Vassh, Erika M. Holmbeck, Matthew R. Mumpower, Rebecca Surman, John J. Cowan, et al.

▲ 鏈接：

https://www.science.org/doi/10.1126/science.adf1341

▲ 摘要：

最重的化學元素是在中子星合并或超新星爆發過程中由快速中子捕獲過程（r-過程）自然產生的。人們對比鈾重元素（超鈾原子核）的r-過程產生知之甚少，尚無法進行實驗，因此必須使用核合成模型進行推演。

研究組分析了r過程元素增強的恒星樣本中的元素豐度。釕、銠、鈀和銀元素的豐度（原子序數Z = 44至47；質量數A = 99至110）與較重元素（63≤Z≤78，A > 150）的豐度相關。相鄰元素（34≤Z≤42和48≤Z≤62）之間不存在相關性。

研究組將此解釋為超鈾原子核的裂變碎片對豐度有貢獻的證據。該結果表明，在r過程事件中會產生質量數>260的富中子核。

▲ Abstract：

The heaviest chemical elements are naturally produced by the rapid neutron-capture process (r-process) during neutron star mergers or supernovae. The r-process production of elements heavier than uranium (transuranic nuclei) is poorly understood and inaccessible to experiments so must be extrapolated by using nucleosynthesis models. We examined element abundances in a sample of stars that are enhanced in r-process elements. The abundances of elements ruthenium, rhodium, palladium, and silver (atomic numbers Z = 44 to 47; mass numbers A = 99 to 110) correlate with those of heavier elements (63 ≤ Z ≤ 78, A > 150). There is no correlation for neighboring elements (34 ≤ Z ≤ 42 and 48 ≤ Z ≤ 62). We interpret this as evidence that fission fragments of transuranic nuclei contribute to the abundances. Our results indicate that neutron-rich nuclei with mass numbers >260 are produced in r-process events.

物理學Physics

On-demand entanglement of molecules in a reconfigurable optical tweezer array

可重構光鑷陣列中分子的按需糾纏

▲ 作者：Connor M. Holland, Yukai Lu & Lawrence W. Cheuk

▲ 鏈接：

https://www.science.org/doi/10.1126/science.adf4272

▲ 摘要：

量子糾纏對于許多量子應用至關重要，包括量子信息處理、量子模擬和量子增強傳感。由于其豐富的內部結構和相互作用，人們認為分子是量子科學頗有前景的平臺。然而，單獨控制分子的確定性糾纏一直是個長期存在的實驗挑戰。

研究組展示了單獨制備分子的按需糾纏，利用可重構光鑷陣列制備的分子對之間的電偶極相互作用，確定性地創建了貝爾分子對。該研究結果展示了量子應用所需的關鍵構建塊，并有望推進利用捕獲分子的量子增強基礎物理測試。

▲ Abstract：

Entanglement is crucial to many quantum applications, including quantum information processing, quantum simulation, and quantum-enhanced sensing. Because of their rich internal structure and interactions, molecules have been proposed as a promising platform for quantum science. Deterministic entanglement of individually controlled molecules has nevertheless been a long-standing experimental challenge. We demonstrate on-demand entanglement of individually prepared molecules. Using the electric dipolar interaction between pairs of molecules prepared by using a reconfigurable optical tweezer array, we deterministically created Bell pairs of molecules. Our results demonstrate the key building blocks needed for quantum applications and may advance quantum-enhanced fundamental physics tests that use trapped molecules.

材料科學Materials Science

Self-enhancing sono-inks enable deep-penetration acoustic volumetric printing

自增強聲納油墨可實現深穿透聲學立體打印

▲ 作者：Xiao Kuang, Qiangzhou Rong, Saud Belal, Tri Vu, Alice M. López López, Nanchao Wang, et al.

▲ 鏈接：

https://www.science.org/doi/10.1126/science.adi1563

▲ 摘要：

立體打印是一種新興的增材制造技術，通過放棄逐步更新墨水的步驟，可提高生成對象的打印速度和表面質量。現有的立體打印技術幾乎完全依靠光能來觸發透明油墨中的光聚合，這限制了材料選擇和構建尺寸。

研究組報道了一種用于深穿透聲學立體打印（DAVP）的自增強超聲油墨（或聲納油墨）設計及相應的聚焦超聲書寫技術。采用實驗和聲學建模的方法來研究頻率和掃描速率相關的聲學打印行為。

DAVP實現了低聲流、快速聲熱聚合和大印刷深度的關鍵特性，可打印各種形狀的體積水凝膠和納米復合材料（無論其光學性質如何）。DAVP還在生物組織中實現了厘米深度的打印，為微創醫學鋪平了道路。

▲ Abstract：

Volumetric printing, an emerging additive manufacturing technique, builds objects with enhanced printing speed and surface quality by forgoing the stepwise ink-renewal step. Existing volumetric printing techniques almost exclusively rely on light energy to trigger photopolymerization in transparent inks, limiting material choices and build sizes. We report a self-enhancing sonicated ink (or sono-ink) design and corresponding focused-ultrasound writing technique for deep-penetration acoustic volumetric printing (DAVP). We used experiments and acoustic modeling to study the frequency and scanning rate–dependent acoustic printing behaviors. DAVP achieves the key features of low acoustic streaming, rapid sonothermal polymerization, and large printing depth, enabling the printing of volumetric hydrogels and nanocomposites with various shapes regardless of their optical properties. DAVP also allows printing at centimeter depths through biological tissues, paving the way toward minimally invasive medicine.

化學Chemistry

Kinetic and thermodynamic control of C(sp2)–H activation enables site-selective borylation

C(sp2)-H活化的動力學和熱力學控制實現了位點選擇性硼化反應

▲ 作者：Jose B. Roque, Alex M. Shimozono, Tyler P. Pabst, Gabriele Hierlmeier, Paul O. Peterson & Paul J. Chirik

▲ 鏈接：

https://www.science.org/doi/10.1126/science.adj6527

▲ 摘要：

在不依賴空間效應或定向基團的情況下區分電子上不同的碳氫鍵（C-H）的催化劑頗難設計。

在這項工作中，研究組描述了由N-烷基咪唑取代吡啶二卡賓（ACNC）螯合配體負載的鈷預催化劑，可以實現氟代芳烴的非定向遠程硼化，并將范圍擴大到包括富電子芳烴、吡啶、三氟和二氟甲基化芳烴，從而解決了第一排過渡金屬C-H官能化催化劑的主要限制之一。

盡管鄰位C-H活化產生的鈷芳基配合物在熱力學上更優，但機制研究表明間位C-H活化在動力學上更優。因此，該研究使用單一預催化劑初步證明了C-H硼化反應中的可切換位點選擇性可起到硼試劑的作用。

▲ Abstract：

Catalysts that distinguish between electronically distinct carbon-hydrogen (C–H) bonds without relying on steric effects or directing groups are challenging to design. In this work, cobalt precatalysts supported by N-alkyl-imidazole–substituted pyridine dicarbene (ACNC) pincer ligands are described that enable undirected, remote borylation of fluoroaromatics and expansion of scope to include electron-rich arenes, pyridines, and tri- and difluoromethoxylated arenes, thereby addressing one of the major limitations of first-row transition metal C–H functionalization catalysts. Mechanistic studies established a kinetic preference for C–H bond activation at the meta-position despite cobalt-aryl complexes resulting from ortho C–H activation being thermodynamically preferred. Switchable site selectivity in C–H borylation as a function of the boron reagent was thereby preliminarily demonstrated using a single precatalyst.

地球科學Earth Science

Drought sensitivity in mesic forests heightens their vulnerability to climate change

濕地森林的干旱敏感性加劇了其對氣候變化的脆弱性

▲ 作者：Robert Heilmayr, Joan Dudney & Frances C. Moore

▲ 鏈接：

https://www.science.org/doi/10.1126/science.adi1071

▲ 摘要：

氣候變化正在改變全球森林的結構和功能，因此迫切需要預測哪些森林最容易受到未來更熱、更干燥氣候的影響。

研究組分析了122個物種的660萬個樹木年輪，以評估樹木對水和能量可用性的敏感性。結果發現生長在氣候范圍內濕潤地區的樹木表現出最大的干旱敏感性。為了測試這些干旱敏感性模式如何影響氣候變化的脆弱性，還預測了至2100年的樹木生長情況。

研究結果表明，干旱地區的干旱適應將部分緩沖樹木免受氣候變化的影響。相比之下，生長在氣候范圍內更潮濕、更熱地區的樹木，在氣候變化下可能會遭受意想不到的巨大不利影響。

▲ Abstract：

Climate change is shifting the structure and function of global forests, underscoring the critical need to predict which forests are most vulnerable to a hotter and drier future. We analyzed 6.6 million tree rings from 122 species to assess trees’ sensitivity to water and energy availability. We found that trees growing in wetter portions of their range exhibit the greatest drought sensitivity. To test how these patterns of drought sensitivity influence vulnerability to climate change, we predicted tree growth through 2100. Our results suggest that drought adaptations in arid regions will partially buffer trees against climate change. By contrast, trees growing in the wetter, hotter portions of their climatic range may experience unexpectedly large adverse impacts under climate change.

Watershed sediment cannot offset sea level rise in most US tidal wetlands

美國大多數潮汐濕地的流域沉積物不能抵消海平面上升

▲ 作者：Scott H. Ensign, Joanne N. Halls & Erin K. Peck

▲ 鏈接：

https://www.science.org/doi/10.1126/science.adj0513

▲ 摘要：

流域沉積物可增加潮汐濕地的海拔，以對抗海平面上升，但流域沉積物在何處以及起到多大的作用尚不清楚。

通過結合美國4972條河流及其河口的沉積物負荷和潮汐濕地面積的連續數據集，研究組計算出，在72%的河流中，河流沉積物的增加不足以與海平面上升相抗衡，因為大多數流域太小（中值21平方千米），無法產生足夠的沉積物。

近一半的潮汐濕地將需要10倍以上的河流沉積物來抵消海平面上升，這在某些地區，即使通過拆除大壩也無法實現。認識到流域沉積物對大多數潮汐濕地海拔幾乎無影響后，人們應將研究重點轉向對海拔變化影響最大的生物過程和海岸沉積物動力學。

▲ Abstract：