检索结果-内蒙古大学图书馆

Physical limits on chemical sensing in bounded domains

Physical Review E 2025年第3期111卷 034404-034404页

作者： Daniel R. McCusker David K. Lubensky Applied Physics Graduate Program University of Michigan Ann Arbor Michigan 48109 USA

Cells respond to chemical signals, and the precision with which they can sense these signals is fundamentally limited by the stochastic nature of diffusion and ligand binding. Berg and Purcell famously investigated how well a small sensor in an infinite ligand bath can determine the ligand concentration, and a number of subsequent analyses have refined and built upon their classical estimates. Not all concentration-sensing problems, however, occur in such an infinite geometry. At different scales, subcellular sensors and cells in tissues are both often confronted with signals whose diffusion is affected by confining boundaries. It is thus valuable to understand how basic limits on chemosensation depend on the sensor's size and on its position in the domain in which ligand diffuses. Here we compute how sensor size and proximity to reflecting boundaries affect the diffusion-limited precision of chemosensation for various geometries in one and three dimensions. We derive analytical expressions for the sensing limit in these geometries. Among our conclusions is the surprising result that, in certain circumstances, smaller sensors can be more effective than larger sensors. This effect arises from a trade-off between spatial averaging and time averaging that we analyze in detail. We also find that proximity to confining boundaries can degrade a sensor's precision significantly compared to the precision of the same sensor far from any boundaries.

关键词： Ligands

来源：评论

学校读者我要写书评

暂无评论

Hydrogen and deuterium tunneling in niobium

引用

Physical Review B 2025年第2期111卷 L020103-L020103页

作者： Abdulaziz Abogoda W. A. Shelton I. Vekhter J. A. Sauls Hearne Institute for Theoretical Physics Louisiana State University Baton Rouge Louisiana 70803 USA Applied Physics Graduate Program Northwestern University Evanston Illinois 60208 USA Department of Physics and Astronomy Louisiana State University Baton Rouge Louisiana 70803 USA

We use density functional methods to identify the atomic configurations of H and D atoms trapped by O impurities embedded in bulk Nb. The O atoms are located at the octahedral position in the Nb body-centered cubic (BCC) lattice, and H (D) atoms tunnel between two degenerate tetrahedral sites separated by a mirror plane. Using nudged elastic band (NEB) methods, we calculate the double-well potential for O-H and O-D impurities and the wave functions and tunnel splittings for H and D atoms. Our results agree with those obtained from analysis of heat capacity and neutron scattering measurements on Nb with low concentrations of O-H and O-D.

关键词： Atoms

来源：评论

学校读者我要写书评

暂无评论

Degradation of Organic LEDs Characterized with Algebraic Decay Relaxation Function

Degradation of Organic LEDs Characterized with Algebraic Dec...

引用

Advances in Display Technologies XV 2025

作者： Aygen, Can Richards, Michael Yazdaanpanah, Ramin Kulkarni, Sachin Tanriover, Ibrahim Onsager, Claire Lin, BoYen Lee, Jiun-Haw Aydin, Koray Grayson, Matthew A. Department of Electrical & Computer Engineering Northwestern University EvanstonIL United States Department of Opto-Electronic Engineering National Dong Hwa University Hualien Taiwan Graduate Institute of Photonics and Optoelectronics Department of Electrical Engineering National Taiwan University Taipei Taiwan Program in Applied Physics Northwestern University EvanstonIL United States

ISBN: (纸本)9781510685246

Lifetime studies of organic light emitting diodes are necessary to both understand and mitigate causes of degradation. Here, electroluminescence (EL) studies of green organic light-emitting diode (OLED) pixels are measured continuously using three different dc currents over a period of one week, and their slow EL degradation is accurately fit to an analytical expression with only two fit parameters. The slower-than-exponential EL decay is fit to an empirical unified heavy-tail function that can interpolate between power-law algebraic decays (AD) and stretched-exponential decays (SE). Whereas SE and AD are largely indistinguishable down to 50% of the initial luminance, here we report degradation down to 10% of the initial luminance which most closely fits an AD function with remarkable precision over the entire duration of the experiment. All relaxations share the same characteristic exponent β = 0.53 in the power law decay, whereas the characteristic time-scale τ for degradation decreases with a power-law exponent B = 1.9 as the current increases. The high degree of accuracy in the fit allows asymptotic predictions at time scales that are orders of magnitude longer than the duration of the data collection. The voltage across the OLED is simultaneously monitored under constant-current degradation and reveals an early-onset time scale where the voltage reaches a minimum before degradation runoff. © 2025 SPIE.

关键词： Organic light emitting diodes (OLED)

来源：评论

学校读者我要写书评

暂无评论

The effect of stereochemical constraints on the radius of gyration of folded proteins

arXiv

引用

arXiv 2025年

作者： Logan, Jack A. Sumner, Jacob Grigas, Alex T. Shattuck, Mark D. O'Hern, Corey S. Department of Mechanical Engineering Yale University New HavenCT06520 United States Graduate Program in Computational Biology & Biomedical Informatics Yale University New HavenCT06520 United States Integrated Graduate Program in Physical and Engineering Biology Yale University New HavenCT06520 United States Benjamin Levich Institute and Physics Department The City College of New York New YorkNY10031 United States Department of Applied Physics Yale University New HavenCT06520 United States Department of Physics Yale University New HavenCT06520 United States

Proteins are composed of linear chains of amino acids that fold into complex three-dimensional structures. A general feature of folded proteins is that they are compact with a radius of gyration Rg(N) ∼ Nν that obeys power-law scaling with the number of amino acids N in each protein and ν ∼ 1/3. In this study, we investigate the internal scaling of the radius of gyration Rg(n) versus the chemical separation n between amino acids for all subchains of length n. We show that for globular proteins Rg(n) ∼ nν1,2 with a larger exponent ν1 > 1/3 for small n and a smaller exponent ν2 g(N) ∝ Nν. To describe this scaling behavior for Rg(n), we carry out folding simulations for a series of coarse-grained models for proteins beginning with the freely-jointed and freely-rotating chain models composed of spherical monomers and varying degrees of stereochemical constraints. We show that a minimal model, which coarse-grains amino acids into a single spherical backbone atom and one variable-sized spherical side-chain atom, and enforces bend- and dihedral-angle constraints, can recapitulate Rg(n) for x-ray crystal structures of globular proteins. In addition, this model predicts the correct average packing fraction and size of the hydrophobic core, which are two key physical features that can be used to distinguish between computational 'decoys' and correctly folded proteins in protein design applications. © 2025, CC BY.

关键词： Spheres

来源：评论

学校读者我要写书评

暂无评论

Anomalous properties of spark plasma sintered boron nitride solids

引用

Materials Today 2025年 86卷 42-51页

作者： Biswas, Abhijit Serles, Peter Alvarez, Gustavo A. Schimpf, Jesse Hache, Michel Kong, Jonathan Demingos, Pedro Guerra Yuan, Bo Pieshkov, Tymofii S. Li, Chenxi Puthirath, Anand B. Gao, Bin Gray, Tia Zhang, Xiang Murukeshan, Jishnu Vajtai, Robert Dai, Pengcheng Singh, Chandra Veer Howe, Jane Zou, Yu Martin, Lane W. Clancy, James Patrick Tian, Zhiting Filleter, Tobin Ajayan, Pulickel M. Department of Materials Science and Nanoengineering Rice University HoustonTX77005 United States Department of Mechanical & Industrial Engineering University of Toronto 5 King's College Road TorontoM5S 3G8 Canada Sibley School of Mechanical and Aerospace Engineering Cornell University IthacaNY14853 United States Department of Materials Science and Engineering University of California Berkeley94720 United States Department of Materials Science and Engineering University of Toronto 184 College St TorontoM5S 3E4 Canada Department of Physics and Astronomy McMaster University HamiltonL8S 4M1 Canada Applied Physics Graduate Program Smalley-Curl Institute Rice University HoustonTX77005 United States Department of Physics and Astronomy Rice University HoustonTX77005 United States Materials Sciences Division Lawrence Berkeley National Laboratory Berkeley94720 United States

Hexagonal boron nitride (h-BN) is a brittle ceramic with a layered structure, however, recent experiments have suggested that inter-layer structural engineering could be key to new structural and functional properties. Here we report the scalable bulk synthesis of high-density crystalline h-BN solids, by using high-temperature spark plasma sintering (SPS) of h-BN powders, which show high values of mechanical strength, ductility, dielectric constant, thermal conductivity, and exceptional neutron radiation shielding capability. Through exhaustive characterizations we reveal that SPS induces non-basal plane crystallinity, twisting of layers, and facilitates inter-grain fusion with a high degree of in-plane alignment across macroscale dimensions, resulting in near-theoretical density and improved properties. Our findings highlight the importance of material design, via new approaches such as layer twisting and interlayer interconnections, to create novel ceramics with properties that could go beyond their intrinsic limits. © 2025

关键词： Ductility

来源：评论

学校读者我要写书评

暂无评论

Emulating complex synapses using interlinked proton conductors

引用

Physical Review applied 2025年第1期23卷 014027-014027页

作者： Lifu Zhang Ji-An Li Yang Hu Jie Jiang Rongjie Lai Marcus K. Benna Jian Shi Department of Materials Science and Engineering Rensselaer Polytechnic Institute Troy New York 12180 USA Neurosciences Graduate Program University of California San Diego La Jolla California 92093 USA Department of Mathematics Purdue University West Lafayette Indiana 47907 USA Department of Neurobiology School of Biological Sciences University of California at San Diego La Jolla California 92093 USA Department of Physics Applied Physics and Astronomy Rensselaer Polytechnic Institute Troy New York 12180 USA

In terms of energy efficiency and computational speed, neuromorphic electronics based on nonvolatile memory devices are expected to be one of most promising hardware candidates for future artificial intelligence (AI). However, catastrophic forgetting, networks rapidly overwriting previously learned weights when learning new tasks, remains a pivotal obstacle in either digital or analog AI chips for unleashing the true power of brainlike computing. To address catastrophic forgetting in the context of online memory storage, a complex synapse model (the Benna-Fusi model) was proposed recently [M. K. Benna and S. Fusi, Nat. Neurosci. 19, 1697 (2016)], the synaptic weight and internal variables of which evolve following diffusion dynamics. In this work, by designing a proton transistor with a series of charge-diffusion-controlled storage components, we have experimentally realized the Benna-Fusi artificial complex synapse. Memory consolidation from coupled storage components is revealed by both numerical simulations and experimental observations. Different memory timescales for the complex synapse are engineered by the diffusion length of charge carriers and the capacity and number of coupled storage components. The advantages of the demonstrated complex synapse for both memory capacity and memory consolidation are revealed by neural network simulations of face-familiarity detection. Our experimental realization of the complex synapse suggests a promising approach to enhance memory capacity and to enable continual learning.

关键词： Nonvolatile storage

来源：评论

学校读者我要写书评

暂无评论

Optimizing CdS thin films as optical windows in solar cells: A comparative study of cryogenic and classical techniques

引用

applied physics A 2025年第6期131卷 1-17页

作者： Manir, Melih Genç, Gamze Nevruzoglu, Vagif Tomakin, Murat Department of Energy Systems Engineering Erciyes University Kayseri Turkey Energy Systems Engineering Program Graduate School of Natural and Applied Sciences Erciyes University Kayseri Turkey Department of Energy Systems Engineering Recep Tayyip Erdogan University Rize Turkey Electrochemical Storage and Energy Conversion (ESCE) Research Group Erciyes University Kayseri Turkey Department of Physics Recep Tayyip Erdogan University Rize Turkey

In this study, CdS thin films were produced in a quasi-closed volume using two different techniques (classical and cryogenic thermal evaporation techniques) between the 100–573 K substrate temperature, and their characteristic properties (structural, electrical, and optical properties) were investigated. While CdS thin films were produced at 373 K, 473 K, and 573 K substrate temperatures in the classical technique (hot), they were produced at 100–300 K substrate temperature range with 50 K steps in the cryogenic technique (cold). The X-Ray Diffraction (XRD) analysis showed that the CdS thin films grew in a hexagonal structure in the (002) plane at all substrate temperatures. According to the field emission scanning electron microscope (FESEM) images, the thin films produced at 200 K substrate temperature consisted of equally sized spherical grains. This situation shows that the soliton growth mechanism occurs at a substrate temperature of 200 K during the film production process with the cryogenic technique. Due to the characteristic properties of the soliton waves occurring on the substrate surface in the soliton growth mechanism (mass transport), the films grow in a tight-packed form. Therefore, the produced films consist of clusters of equal size, providing a homogeneous surface and a uniform thickness. In addition, Atomic Force Microscope (AFM) and optical analyses showed that the CdS thin film produced at 200 K substrate temperature had the smallest average surface roughness value (Ra) and the highest optical transmittance value. It was found that the energy band gap (2.37–2.47 eV) and resistivity (1.25 × 103–5.39 × 103 Ω-cm) values of CdS thin films increased with decreasing substrate temperature. The carrier density increased with decreasing substrate temperature (3.91 × 1017–1.73 × 1016 cm−3). Energy Dispersive Spectroscopy (EDS) analysis showed that the films grew stoichiometrically at substrate tempe

关键词：

来源：评论

学校读者我要写书评

暂无评论

BPS2025 - Characterization of intrinsically disordered protein-polymer interactions with fluorescence polarization

引用

Biophysical Journal 2025年第3期124卷 164a-164a页

作者： Wesley W. Leung Wenchang Zhou Julea Vlassakis Applied Physics Graduate Program Rice University Houston TX USA Department of Bioengineering Rice University Houston TX USA

来源：评论

学校读者我要写书评

暂无评论

Correlation between complex spin textures and the magnetocaloric and Hall effects in Eu(Ga1−xAlx)4 (x=0.9, 1)

引用

Physical Review B 2025年第16期111卷 165136-165136页

作者： Kelly J. Neubauer Kevin Allen Jaime M. Moya Mason L. Klemm Feng Ye Zachary Morgan Lisa DeBeer-Schmitt Wei Tian Emilia Morosan Pengcheng Dai Department of Physics and Astronomy Rice University Houston Texas 77005 USA Smalley-Curl Institute Rice University Houston Texas 77005 USA Rice Center for Quantum Materials Rice University Houston Texas 77005 USA Applied Physics Graduate Program Rice University Houston Texas 77005 USA Present address: Department of Chemistry Princeton University Princeton New Jersey 08544 USA. Neutron Scattering Division Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA

Determining the electronic phase diagram of a quantum material as a function of temperature (T) and applied magnetic field (H) forms the basis for understanding the microscopic origin of transport properties, such as the anomalous Hall effect (AHE) and topological Hall effect (THE). For many magnetic quantum materials, including EuAl4, a THE arises from a topologically protected magnetic skyrmion lattice with a nonzero scalar spin chirality. We identified a square skyrmion lattice (sSkL) peak in Eu(Ga1−xAlx)4 (x=0.9) identical to the peak previously observed in EuAl4 by performing neutron-scattering measurements throughout the phase diagram. Comparing these neutron results with transport measurements, we found that in both compounds the maximal THE does not correspond to the sSkL area. Instead of the maximal THE, the maximal magnetocaloric-effect boundaries better identify the sSkL lattice phase observed by neutron-scattering measurements. The maximal THE therefore arises from interactions of itinerant electrons with frustrated spin fluctuations in a topologically trivial magnetic state.

关键词： Hall effect

来源：评论

学校读者我要写书评

暂无评论

Tuning the Size and Stiffness of Inflatable Particles

arXiv

引用

arXiv 2025年

作者： Pashine, Nidhi Wang, Dong Baines, Robert Goyal, Medha Shattuck, Mark D. O’Hern, Corey S. Kramer-Bottiglio, Rebecca Department of Mechanical Engineering Yale University New HavenCT06520 United States Department of Physics BioInspired Institute Syracuse University SyracuseNY13244 United States Department of Physics Benjamin Levich Institute City College of New York New York CityNY10031 United States Department of Physics Yale University New HavenCT06520 United States Department of Applied Physics Yale University New HavenCT06520 United States Graduate Program in Computational Biology & Biomedical Informatics Yale University New HavenCT06520 United States

We describe size-varying cylindrical particles made from silicone elastomers that can serve as building blocks for robotic granular materials. The particle size variation, which is achieved by inflation, gives rise to changes in stiffness under compression. We design and fabricate inflatable particles that can become stiffer or softer during inflation, depending on key parameters of the particle geometry, such as the ratio of the fillet radius to the wall thickness, r/t. We also conduct numerical simulations of the inflatable particles and show that they only soften during inflation when localization of large strains occurs in the regime r/t → 0. This work introduces novel particle systems with tunable size and stiffness that can be implemented in numerous soft robotic applications. © 2025, CC BY.

关键词： Stiffness

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：