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== 摘要 ==
* '''原文标题'''：Investigation of O interstitial diffusion in $β$-Ga$_2$O$_3$: direct approach via master diffusion equations
* '''中文标题'''：$β$-Ga$_2$O$_3$中氧间隙扩散的研究：通过主扩散方程的直接方法
* '''发布日期'''：2025-03-03 16:54:55+00:00
* '''作者'''：Grace McKnight, Channyung Lee, Elif Ertekin
* '''分类'''：cond-mat.mtrl-sci, physics.app-ph, physics.comp-ph
*'''原文链接'''：http://arxiv.org/abs/2503.01735v1

'''中文摘要'''：[[单斜晶系]]的$\beta$-[[Ga]]$_2$[[O]]$_3$是一种有前景的[[宽带隙半导体]]材料，由于其低对称性的[[晶体结构]]，表现出复杂的[[各向异性]]扩散特性和[[质量传输]]行为。通过[[第一性原理计算]]结合[[主扩散方程]]，我们确定了中性[[氧间隙]]（$\text{O}_{\text{i}}^{0}$）和带2-电荷的[[氧间隙]]（$\text{O}_{\text{i}}^{2-}$）的三维[[扩散张量]]。通过对[[构型空间]]的系统探索，我们识别了这两种主要电荷态的稳定构型及其相应的[[形成能]]。通过考虑[[间隙]]或[[间隙跳跃]]，连接每一对低能构型，我们构建了三维[[扩散网络]]，并评估了网络中所有[[过渡路径]]的[[跳跃势垒]]。结合（i）[[缺陷构型]]及其[[形成能]]和（ii）连接它们的[[跳跃势垒]]，我们通过[[Onsager方法]]分别构建并求解了$\text{O}_{\text{i}}^{0}$和$\text{O}_{\text{i}}^{2-}$的[[主扩散方程]]，得到了相应的三维[[扩散张量]]D$_{\text{O}_{\text{i}}}^{0}$和D$_{\text{O}_{\text{i}}}^{2-}$。$\text{O}_{\text{i}}^{0}$和$\text{O}_{\text{i}}^{2-}$都表现出沿$b$轴的最快扩散，显示出显著的[[各向异性]]。沿[100]和[$\overline{2}01$]方向预测的[[自扩散系数]]与之前报道的[[同位素标记]][[氧示踪实验]]值吻合良好，突出了该方法在捕捉复杂[[扩散机制]]方面的可靠性。

== 摘要 ==
* '''原文标题'''：Fire danger likely overestimated in future climate projections
* '''中文标题'''：未来气候预测中火灾危险可能被高估
* '''发布日期'''：2025-03-03 18:42:50+00:00
* '''作者'''：Aurora Matteo, Ginés Garnés-Morales, Alberto Moreno, Ribeiro Andreia, César Azorín-Molina, Joaquín Bedia, Francesca Di Giuseppe, Robert J. H. Dunn, Sixto Herrera, Antonello Provenzale, Yann Quilcaille, Miguel Ángel Torres Vázquez, Marco Turco
* '''分类'''：physics.ao-ph
*'''原文链接'''：http://arxiv.org/abs/2503.01818v1
'''原文摘要'''：The Canadian Fire Weather Index (FWI) is widely used to assess wildfire
danger and relies on meteorological data at local noon. However, climate models
often provide only daily aggregated data, which poses a challenge for accurate
FWI calculations in climate change studies. Here, we examine how using daily
approximations for FWI95d -- the annual count of extreme fire weather days
exceeding the 95th percentile of local daily FWI values -- compares to the
standard noon-based approach for the period 1980--2023.
Our findings reveal that FWI95d calculated with noon-specific data increased
globally by approximately 65\%, corresponding to 11.66 additional extreme fire
weather days over 44 years. In contrast, daily approximations tend to
overestimate these trends by 5--10\%, with combinations involving minimum
relative humidity showing the largest divergences. Globally, up to 15 million
km$^2$, particularly in the western United States, southern Africa, and parts
of Asia, exhibit significant overestimations. Among our daily approximation
methods, the least biased proxy is the one that uses daily mean data for all
variables.
We recommend (i) prioritizing the inclusion of sub-daily meteorological data
in future climate model intercomparison projects to enhance FWI accuracy, and
(ii) adopting daily mean approximations as the least-biased alternative if
noon-specific data are unavailable.
'''中文摘要'''：[[加拿大火灾天气指数]]（FWI）被广泛用于评估[[野火]]风险，并依赖于当地中午的[[气象数据]]。然而，[[气候模型]]通常仅提供每日汇总数据，这为[[气候变化]]研究中的准确FWI计算带来了挑战。本文研究了在1980年至2023年期间，使用每日近似值计算FWI95d（即超过当地每日FWI值第95百分位数的极端火灾天气日数的年计数）与标准基于中午的方法的比较。
我们的研究结果表明，使用中午特定数据计算的FWI95d在全球范围内增加了约65%，相当于44年内增加了11.66个极端火灾天气日。相比之下，每日近似值往往会高估这些趋势5-10%，其中涉及最低[[相对湿度]]的组合显示出最大的差异。在全球范围内，多达1500万平方公里的地区，特别是[[美国西部]]、[[南部非洲]]和[[亚洲]]部分地区，显示出显著的高估。在我们的每日近似方法中，偏差最小的代理是使用所有变量的每日平均值的方法。
我们建议：（i）在未来的气候模型比较项目中优先纳入次每日气象数据，以提高FWI的准确性；（ii）如果无法获得中午特定数据，则采用每日平均值近似作为偏差最小的替代方案。

== 摘要 ==
* '''原文标题'''：A COMSOL framework for predicting hydrogen embrittlement -- Part II: phase field fracture
* '''中文标题'''：用于预测氢脆的COMSOL框架——第二部分：相场断裂
* '''发布日期'''：2025-03-03 17:39:02+00:00
* '''作者'''：A. Díaz, J. M. Alegre, I. I. Cuesta, E. Martínez-Pañeda
* '''分类'''：cs.CE, physics.app-ph, physics.chem-ph
*'''原文链接'''：http://arxiv.org/abs/2503.01765v1
'''原文摘要'''：Prediction of hydrogen embrittlement requires a robust modelling approach and
this will foster the safe adoption of hydrogen as a clean energy vector. A
generalised computational model for hydrogen embrittlement is here presented,
based on a phase field description of fracture. In combination with Part I of
this work, which describes the process of hydrogen uptake and transport, this
allows simulating a wide range of hydrogen transport and embrittlement
phenomena. The material toughness is defined as a function of the hydrogen
content and both elastic and elastic-plastic material behaviour are
incorporated, enabling to capture both ductile and brittle fractures, and the
transition from one to the other. The accumulation of hydrogen near a crack tip
and subsequent embrittlement is numerically evaluated in a single-edge cracked
plate, a boundary layer model and a 3D vessel case study, demonstrating the
potential of the framework. Emphasis is placed on the numerical implementation,
which is carried out in the finite element package COMSOL Multiphysics, and the
models are made freely available.
'''中文摘要'''：预测[[氢脆]]需要一种稳健的建模方法，这将促进[[氢]]作为[[清洁能源]]载体的安全采用。本文提出了一种基于[[断裂相场]]描述的氢脆通用计算模型。结合本工作的第一部分，该部分描述了氢的[[吸收]]和[[传输]]过程，这使得模拟广泛的氢传输和氢脆现象成为可能。[[材料韧性]]被定义为氢含量的函数，并且结合了[[弹性]]和[[弹塑性]]材料行为，从而能够捕捉到[[韧性断裂]]和[[脆性断裂]]以及两者之间的转变。在[[单边裂纹板]]、[[边界层模型]]和[[三维容器]]案例研究中，数值评估了[[裂纹尖端]]附近氢的积累和随后的氢脆，展示了该框架的潜力。重点放在数值实现上，该实现是在[[有限元软件]][[COMSOL Multiphysics]]中进行的，并且模型是免费提供的。

== 摘要 ==
* '''原文标题'''：Improved sensitivity in the search for rare decays of Gd isotopes
* '''中文标题'''：改进的Gd同位素稀有衰变搜索灵敏度
* '''发布日期'''：2025-03-03 15:20:27+00:00
* '''作者'''：B. Lehnert, S. S. Nagorny, M. Thiesse, F. Ferella, M. Laubenstein, E. Meehan, S. Nisi, P. R. Scovell
* '''分类'''：nucl-ex, hep-ex
*'''原文链接'''：http://arxiv.org/abs/2503.01641v1
'''原文摘要'''：Gadolinium is widely used in multiple low-background experiments, making its
isotopes accessible for rare decay searches both in-situ and through
radiopurity screening data. This study presents an improved search for rare
alpha and double-beta decay modes in $^{152}$Gd, $^{154}$Gd, and $^{160}$Gd
isotopes using ultra-low background HPGe detectors at the Boulby Underground
Screening (BUGS) facility. A total exposure of 6.7 kg$\cdot$yr of natural
gadolinium was achieved using gadolinium sulfate octahydrate
$(\text{Gd}_2(\text{SO}_4)_3 \cdot 8\text{H}_2\text{O})$ samples, originally
screened for radiopurity prior to their deployment in the Super-Kamiokande
neutrino experiment. Due to the detection methodology, only decays into excited
states accompanied by gamma-ray emission were accessible. A Bayesian analysis
incorporating prior experimental results was employed, leading to new lower
half-life limits in the range of $10^{19} - 10^{21}$ years - an improvement of
approximately two orders of magnitude over previous constraints. No
statistically significant decay signals were observed. These results
demonstrate the effectiveness of repurposing large-scale radiopurity screening
campaigns for fundamental physics research.
'''中文摘要'''：[[钆]]被广泛应用于多种低本底实验中，使其同位素在原位和通过放射性纯度筛选数据中进行稀有衰变搜索成为可能。本研究利用[[Boulby地下筛选设施]]（BUGS）的超低本底高纯锗探测器，对$^{152}$Gd、$^{154}$Gd和$^{160}$Gd同位素的稀有[[α衰变]]和[[双β衰变]]模式进行了改进的搜索。使用[[硫酸钆八水合物]]$(\text{Gd}_2(\text{SO}_4)_3 \cdot 8\text{H}_2\text{O})$样品，实现了总计6.7 kg$\cdot$年的天然钆暴露量，这些样品最初在部署到[[超级神冈中微子实验]]之前进行了放射性纯度筛选。由于检测方法的原因，只有伴随[[γ射线]]发射的激发态衰变是可检测的。采用了结合先前实验结果的[[贝叶斯分析]]，得出了$10^{19} - 10^{21}$年范围内的新下限半衰期——比之前的限制提高了大约两个数量级。未观察到统计上显著的衰变信号。这些结果证明了将大规模放射性纯度筛选活动重新用于基础物理研究的有效性。