ChinesePhysicsB的个人博客分享 http://blog.sciencenet.cn/u/ChinesePhysicsB

博文

[转载]CPB封面文章和亮点文章 | 2022年第4期

已有 718 次阅读 2022-4-25 15:50 |系统分类:论文交流|文章来源:转载

1.jpg

封面文章.png

Non-invasive and low-artifact in vivo brain imaging by using a scanning acoustic-photoacoustic dual mode microscopy

Wentian Chen(陈文天), Chao Tao(陶超), Zizhong Hu(胡仔仲), Songtao Yuan(袁松涛), Qinghuai Liu(刘庆淮), and Xiaojun Liu(刘晓峻)

Chin. Phys. B, 2022, 31 (4):  044304

文章亮点介绍.png

脑成像一直是生物医学成像研究的热门方向之一。声学分辨率光声显微镜系统具有光吸收对比度高、穿透深度大、成像分辨能力强的优势,可以提供一定深度范围内小动物脑部血管的高分辨率图像。但是,由于脑组织上方存在复杂的声散射层状媒质(如颅骨层、头皮层等),光声信号在传播过程中会发生多次反射,并在深层组织的图像上产生伪像。因此,如想利用光声成像技术做无损穿颅成像,该问题会严重限制此技术的正常使用。


针对此问题,本工作提出了一种结合声学分辨率光声显微镜和超声显微镜成像的低伪像光声显微镜成像技术,可以抑制多层声散射媒质产生的反射伪像。由于光声信号和超声回波传播特征的相似性,超声回波可以用来得到抑制反射伪像的传递函数,从而得到低伪像的光声图像。我们将该方法应用于无损的小鼠活体穿颅成像实验中,结果表明本方法可以成功地得到低伪像的脑成像结果。


本工作实现了一种在不破坏生物组织的前提下,有效提升光声穿颅成像图像质量的方式,在生物医学成像领域具有重要价值。

原文链接

PDF

2.png

Fig. 9. Comparisons of the images in xz and yz sections obtained by SAM, conventional AR-PAM and the proposed method. The top row [(a), (d), (g), (j)] gives the SAM images of the yz plane B1, xz plane B2, B3, B4. The US echoes can reveal the profiles of the PDMS film layer (purple arrow), scalp (green arrow) and the skull (white arrow). The middle row [(b), (e), (h), (k)] shows the results obtained by a conventional AR-PAM scheme. The red arrow, orange arrow, yellow arrow in (b) point out the reflected artifacts, which correspond to the artifacts indicated in (e) (red arrow), (h) (orange arrow), (k) (yellow arrow), respectively. The corresponding LAPAM images are shown in the bottom row [(c), (f), (i), (l)], where the artifacts pointed out in the middle column are suppressed and the real images of vessels are still left.


亮点文章.png

Solving quantum rotor model with different Monte Carlo techniques

Weilun Jiang(姜伟伦), Gaopei Pan(潘高培), Yuzhi Liu(刘毓智), and Zi-Yang Meng(孟子杨)

Chin. Phys. B, 2022, 31 (4):  040504

文章亮点介绍.png

Kosterlitz-Thouless (KT) 相变是真正意义上的第一种拓扑相变。它可以用来描述经典XY模型的临界行为,通过降低温度实现无序相到超流相的转变。在经典XY模型的基础上增加角度的涨落项形成量子转子模型,可以实现零温量子相变,相变类型属于(2+1)d XY普适类。量子转子模型可以用来描述 Bose-Hubbard 模型中从超流体到莫特绝缘体的量子相变,与目前超冷原子和光晶格实验进展紧密相关。


此相变点不能通过解析求解,但可在数值方法中使用蒙特卡洛算法模拟该系统。然而,在靠近相变点处会出现蒙特卡洛更新的临界慢化现象,因此寻找有效的蒙特卡洛更新方法不仅可以对该模型的物理量的变化做很好的计算,还为研究更复杂的模型,诸如连续场耦合费米子问题,即赝能隙与非费米液体的晶格模型的大尺度计算提供了可能。


本文系统考察了五种不同的蒙特卡洛更新方法,分别为局域更新、局域更新与过弛豫方法、Wolff团簇更新、杂化蒙特卡洛方法、杂化蒙卡与傅里叶加速,详细比较了其在量子临界点处的更新效率,为以量子转子模型为基础的微观模型的大规模数值计算提供了基本的选项。为了有效地得到统计独立的构型,我们发现一方面需要估计更新方法的自关联时间,另一方面需要得到该方法在实际计算中所用的计算时长。我们仔细计算了五种方法对于能量和磁矩的自关联曲线,并拟合自关联时间随体系尺寸的标度形式。统计自关联的存在会影响测量数据的样本标准差,文中采用样本重组的方式得到不同方法的样本标准差。另外结合计算机时,最终比较各方法对于两种观测量的更新效率。比较发现:Wolff方法表现优异,但较难推广到有复杂相互作用的模型,杂化蒙卡与傅里叶加速在小尺寸下效果较好,并且有可调参数的优化空间。本文的分析结果可以为连续场模型,诸如O(2),O(3),phi4耦合费米子模型的更新方法的选择提供参考。

原文链接

PDF

3.png

Fig. 6. The CPU hour TM spent for each Monte Carlo scheme to obtain the error of 0.001 of static uniform magnetization M, as a function of system sizes L. As expected, although the HM scheme has shorter autocorrelation time compared with LM scheme, it actually spends more CPU time on obtaining the shorter autocorrelation time mainly due to the leapfrog processes therein. Whereas with FA scheme, both the autocorrelation time and the CPU hour spent are much less compared with LM, OR, HM schemes in reaching the same errorbar. The less CPU hours spent is for the WC scheme, owing to both the small autocorrelation time and less number of operations in the algorithm, thus it will be the best to calculate the bigger sizes in the quantum rotor model.


亮点文章.png

The 50 nm-thick yttrium iron garnet films with perpendicular magnetic anisotropy

Shuyao Chen(陈姝瑶), Yunfei Xie(谢云飞), Yucong Yang(杨玉聪), Dong Gao(高栋), Donghua Liu(刘冬华), Lin Qin(秦林), Wei Yan(严巍), Bi Tan(谭碧), Qiuli Chen(陈秋丽), Tao Gong(龚涛), En Li(李恩), Lei Bi(毕磊), Tao Liu(刘涛), and Longjiang Deng(邓龙江)

Chin. Phys. B, 2022, 31 (4):  048503

文章亮点介绍.png

兼具垂直磁各向异性(PMA)和低磁阻尼系数的磁性薄膜是下一代自旋电子学和自旋波器件中理想的功能薄膜材料。因此,制备高质量具有PMA的钇铁石榴石(YIG)薄膜目前是该领域的一个研究热点。这主要是因为YIG是迄今被发现的磁阻尼系数最低的材料,而且YIG具有相对较大的磁致伸缩常数,可通过外延生长的方式引入四方晶格畸变来获得足够的PMA。已经有一些研究小组在不同的非磁性石榴石衬底上成功制备出了具有PMA的YIG薄膜。然而,随着YIG薄膜厚度的增加,其应力很容易弛豫,因而目前还很难制备出超过20 nm厚的PMA YIG薄膜,这成为了制约其未来应用的一个重要技术瓶颈。


为解决上述问题,本文采用磁控溅射的方法,成功地在与YIG存在适量的晶格失配的掺杂石榴石衬底(sGGG)上外延生长了具有PMA的YIG薄膜。我们通过优化生长条件和退火条件,使得厚度达50 nm的YIG薄膜仍然可以很好地保持均匀的面内拉伸应力,这是迄今为止报道的具有PMA的最厚的纯YIG薄膜。我们的工作证明了使用sGGG衬底生长兼具PMA和低磁阻尼系数的YIG厚膜的可行性,这对于开发高速度、低能耗的自旋电子学和自旋波器件具有重要的意义。

原文链接

PDF

4.png

Fig. 3. Hysteresis loops of the YIG films measured with magnetic field applied in-plane and out-of-plane.


亮点文章.png

Self-screening of the polarized electric field in wurtzite gallium nitride along [0001] direction

Qiu-Ling Qiu(丘秋凌), Shi-Xu Yang(杨世旭), Qian-Shu Wu(吴千树), Cheng-Lang Li(黎城朗), Qi Zhang(张琦), Jin-Wei Zhang(张津玮), Zhen-Xing Liu(刘振兴), Yuan-Tao Zhang(张源涛), and Yang Liu(刘扬)

Chin. Phys. B, 2022, 31 (4):  047103

文章亮点介绍.png

极化特性是纤锌矿III族氮化物半导体材料的重要特质之一,是构建时下在消费类电子快充领域和5G通讯领域起到核心作用的高性能GaN功率电子开关器件和GaN微波射频功率晶体管的关键因素。全面地深入细致理解“极化”相关的效应,对未来III族氮化物半导体新型器件形态的构建具有重要的科学意义和实用价值。由于极化电场的静电库伦作用导致半导体内载流子重新分布,补偿极化电荷,进而减弱或抵消内部电场的现象被称为极化电场自屏蔽效应。本文通过TCAD仿真的方法,展示了纤锌矿GaN半导体中极化电场的自屏蔽现象。阐明自屏蔽电荷的基本来源,围绕着实际非故意掺杂Ga极性GaN半导体的材料状态,讨论了表面施主态和n型载流子浓度对自屏蔽的作用效果。研究表明,本征的和仅具有施主表面态的GaN体材料中极化电场无法被完全屏蔽,其屏蔽程度与材料厚度有关;而对于具有一定厚度(该厚度与表面态和电子浓度相关)的n型GaN体材料,其极化电场就能够被完全屏蔽。


本研究团队计划陆续报道基于单异质结和多异质结氮化物半导体的自屏蔽规律,相信相关结论可以为III族氮化物极化效应理论体系的建立提供进一步的补充。

原文链接

PDF

5.png

Fig. 1. Part I: the material structure and energy band diagram of intrinsic bulk GaN. Part II: the material structure and energy band diagram of bulk GaN with only Ga-face donor-like surface states. Where the tGaN is the thickness of bulk GaN, tcr is the critical thickness of the ideal intrinsic GaN, EDD is donor-like surface state level. The GaN polarized electric field in part I and II can only be partially screened. Part III: the material structure and energy band diagram of bulk GaN with donor-like impurities. Where the Wd is width of depletion region formed by donor impurity ionization. In the GaN with donor-like impurities, the polarized electric field can always be completely screened if tGaN>Wd, as shown in part III.


公用专题推荐.png

TOPICAL REVIEW — Progress in thermoelectric materials and devices

SPECIAL TOPIC — Emerging photovoltaic materials and devices

SPECIAL TOPIC — Organic and hybrid thermoelectrics

SPECIAL TOPIC — Superconductivity in vanadium-based kagome materials

SPECIAL TOPIC— Interdisciplinary physics: Complex network dynamics and emerging technologies

SPECIAL TOPIC — Non-Hermitian physics

SPECIAL TOPIC — Unconventional superconductivity

SPECIAL TOPIC — Two-dimensional magnetic materials and devices

SPECIAL TOPIC — Ion beam modification of materials and applications

SPECIAL TOPIC — Quantum computation and quantum simulation

SPECIAL TOPIC —Twistronics

SPECIAL TOPIC — Machine learning in condensed matter physics

SPECIAL TOPIC — Phononics and phonon engineering

SPECIAL TOPIC — Water at molecular level

SPECIAL TOPIC — Optical field manipulation

SPECIAL TOPIC — Modeling and simulations for the structures and functions of proteins and nucleic acids

SPECIAL TOPIC —Terahertz physics

SPECIAL TOPIC — Ultracold atom and its application in precision measurement

SPECIAL TOPIC — Topological 2D materials

SPECIAL TOPIC — Active matters physics

SPECIAL TOPIC — Physics in neuromorphic devices

SPECIAL TOPIC — Advanced calculation & characterization of energy storage materials & devices at multiple scale

TOPICAL REVIEW — Advanced calculation & characterization of energy storage materials & devices at multiple scale

TOPICAL REVIEW — Quantum dot displays

TOPICAL REVIEW — CALYPSO structure prediction methodology and its applications to materials discovery

SPECIAL TOPIC — A celebration of the 100th birthday of Kun Huang

TOPICAL REVIEW — A celebration of the 100th birthday of Kun Huang

SPECIAL TOPIC — Strong-field atomic and molecular physics

TOPICAL REVIEW — Strong-field atomic and molecular physics

TOPICAL REVIEW — Topological semimetals

SPECIAL TOPIC — Topological semimetals

SPECIAL TOPIC — Photodetector: Materials, physics, and applications

TOPICAL REVIEW — Photodetector: Materials, physics, and applications

TOPICAL REVIEW — Fundamental research under high magnetic fields

Virtual Special Topic — High temperature superconductivity

Virtual Special Topic — Magnetism and Magnetic Materials


公用底.png

官网:http://cpb.iphy.ac.cn  

           https://iopscience.iop.org/journal/1674-1056




https://blog.sciencenet.cn/blog-3377544-1335564.html

上一篇:[转载]中科院物理所学术服务部英文刊招聘启事
下一篇:[转载]CPB2022年第4期编辑推荐文章
收藏 IP: 159.226.35.*| 热度|

0

该博文允许注册用户评论 请点击登录 评论 (0 个评论)

数据加载中...

Archiver|手机版|科学网 ( 京ICP备07017567号-12 )

GMT+8, 2024-7-19 13:03

Powered by ScienceNet.cn

Copyright © 2007- 中国科学报社

返回顶部