bluuebunny/crossref_metadata_2025 huggingface dataset:
Advances in dielectric polymer composites provide new ways to study ultra-low filler content
Authors: Liebendorfer Adam
Published: February 2022

Small amounts of inorganic nanofiller material may boost performance for use in next-generation high-energy-density dielectrics.
Singular rank one perturbations
Authors: Astaburuaga M. A. , Cortés V. H. , Fernández C. , Del Río R.
Published: February 2022

In this paper, A = B + V represents a self-adjoint operator acting on a Hilbert space H. We set a general theoretical framework and obtain several results for singular perturbations of A of the type Aβ = A + βτ*τ for τ being a functional defined in a subspace of H. In particular, we apply these results to Hβ = −Δ + V + β|δ⟩⟨δ|, where δ is the singular perturbation given by δ(φ) = ∫Sφ dσ, where S is a suitable hypersurface in Rn. Using the fact that the singular perturbation τ*τ is a sort of rank one perturbation of the operator A, it is possible to prove the invariance of the essential spectrum of A under these singular perturbations. The main idea is to apply an adequate Krein’s formula in this singular framework. As an additional result, we found the corresponding relationship between the Green’s functions associated with the operators H0 = Δ + V and Hβ, and we give a result about the existence of a pure point spectrum (eigenvalues) of Hβ. We also study the case β goes to infinity.
Non-symmetric blowing-up solutions for a class of Liouville equations in the ball
Authors: D’Aprile Teresa
Published: February 2022

We are concerned with the existence of blowing-up solutions to the following boundary value problem: −Δv = λV(x)ev in  B1, v = 0 on  ∂B1, where B1 is the unit ball in R2, V(x) is a positive smooth potential, and λ > 0 is a small parameter. We assume that the potential V satisfies some suitable assumptions in terms of the second and the fourth derivatives at 0, and we find a solution that exhibits a non-symmetric blow-up profile as λ → 0+.
Meso-scale simulation of energetic materials. I. A method for generating synthetic microstructures using deep feature representations
Authors: Roy Sidhartha , Nguyen Yen Thi , Neal Christopher , Baek Stephen , Udaykumar H. S.
Published: February 2022

The response of a wide class of heterogeneous energetic materials (HEs) to loads is determined by dynamics at the meso-scale, i.e., by physicochemical processes in their underlying microstructure. Structure–property–performance (S–P–P) linkages for such materials can be developed in a multi-scale framework, connecting the physics and thermophysical properties at the meso-scale to response at the macro-scale. Due to the inherent stochasticity of the microstructure, ensembles of microstructures are required to conduct meso-scale simulations to establish S–P–P linkages. Here, a deep neural network-based method called deep feature representation is applied to generate a range of material microstructures from heterogeneous energetic materials to metal foams and metallic mixtures. The method allows for the generation of stochastic microstructures using a single real microstructure as the input and is not limited to low packing density or topological complexity of solids. In its application to pressed energetic materials, we show that qualitative and quantitative features of real (i.e., imaged) microstructures are captured in the synthetic microstructures. Therefore, a stochastic ensemble of synthetic microstructures can be created for use in reactive meso-scale simulations to relate the microstructures of HEs to their performance. While the focus is on pressed HE microstructures, we also show that the method is general and useful for generating microstructures for in silico experiments for a wide range of composite/multiphase materials, which can be used to establish S–P–P linkages.
All sp2 hybridization BN polymorphs with wide bandgap
Authors: Fan Qingyang , Wu Nan , Yang Runling , Zhang Wei , Yu Xinhai , Yun Sining
Published: February 2022

Four new boron nitride polymorphs hP24 BN, hP18-I BN, mP36 BN, and hP18-II BN with sp2 hybridization are investigated in this study by first-principles calculations, including the structural properties, stability, elastic properties, anisotropy, and electronic properties. Predicted by the electronic band structure, all the BN polymorphs in hP24, hP18-I, mP36, and hP18-II phase are wide bandgap semiconductor materials with a bandgap of 2.97–4.72 eV. Meanwhile, the bandgap of hP24 BN is larger than that of ZnO, and the bandgaps of hP18-I BN, mP36 BN, and hP18-II BN are larger than those of GaN and SiC. The new boron nitride polymorphs have mechanical stability, dynamic stability, and thermodynamic stability by analyzing the elastic constants, phonon spectra, and related enthalpies. The values of B/G of hP24 BN, hP18-I BN, mP36 BN, and hP18-II BN are all larger than 1.75, which confirms that they are ductile materials. Their densities are around 2.100 g/cm3, which are smaller than that of the c-BN (3.466 g/cm3). BN polymorphs in this study show different degrees of anisotropy in Young's modulus, and hP24 BN has the largest anisotropy in Young's modulus, while mP36 BN displays the smallest Young's modulus anisotropy.
Block copolymer self-assembly: Melt and solution by molecular density functional theory
Authors: Xi Shun , Zhu Yiwei , Lu Jinxin , Chapman Walter G.
Published: February 2022

The self-assembly of block copolymer melts and solutions with two-dimensional density inhomogeneity is studied using modified inhomogeneous statistical associating fluid theory (iSAFT). A real-space combinatorial screening method under density functional theory formalism is proposed and used to map out the phase diagram of block copolymer melts including order–disorder transitions and order–order transitions. The predicted phase diagram agrees well with molecular dynamics simulation and self-consistent field theory. The compressibility effect on order–disorder transition temperature for block copolymer melts is modeled using iSAFT. The pressure induced temperature change by theory has a similar trend to experimental studies. Then, the lyotropic and thermotropic self-assembly phase behavior of block copolymer solutions is investigated. Detailed density distributions by iSAFT provide insight into the lyotropic properties of the block copolymer solutions at the molecular level. The effect of the block copolymer molecular architecture is studied by comparing block copolymers with different molecular packing parameters. Block copolymer solutions in the inverted hexagonal phase are predicted by theory for the block copolymer having a large molecular packing parameter. Finally, solvent selectivity is studied by modeling the block copolymers in a neutral good solvent. The enhanced local solvent concentration predicted by theory explains the reason for fewer ordered phases found in experiments.
On the population density of the argon excited levels in a high power impulse magnetron sputtering discharge
Authors: Rudolph M. , Revel A. , Lundin D. , Brenning N. , Raadu M. A. , Anders A. , Minea T. M. , Gudmundsson J. T.
Published: February 2022

Population densities of excited states of argon atoms in a high power impulse magnetron sputtering (HiPIMS) discharge are examined using a global discharge model and a collisional-radiative model. Here, the ionization region model (IRM) and the Orsay Boltzmann equation for electrons coupled with ionization and excited states kinetics (OBELIX) model are combined to obtain the population densities of the excited levels of the argon atom in a HiPIMS discharge. The IRM is a global plasma chemistry model based on particle and energy conservation of HiPIMS discharges. OBELIX is a collisional-radiative model where the electron energy distribution is calculated self-consistently from an isotropic Boltzmann equation. The collisional model constitutes 65 individual and effective excited levels of the argon atom. We demonstrate that the reduced population density of high-lying excited argon states scales with (p*)−6, where p* is the effective quantum number, indicating the presence of a multistep ladder-like excitation scheme, also called an excitation saturation. The reason for this is the dominance of electron impact processes in the population and de-population of high-lying argon states in combination with a negligible electron–ion recombination.
Development of a portable time-of-flight mass spectrometer prototype using a cold electron source
Authors: Jeong Wanseop , Kim Hyun Sik , Kang Byeongwon
Published: February 2022

Fundamental obstacles toward the development of a portable time-of-flight mass spectrometer (TOF MS) are ionization sources and vacuum systems. To overcome these, a cold electron source (CES) and a pulse valve are introduced in this study to examine the possibility of developing a portable TOF MS. The CES is developed using a microchannel plate electron multiplier radiated by ultraviolet photons from a light-emitting diode. The CES is controlled using short pulses to generate accelerated electrons that ionize a substrate surface. A 10 ns CES pulse produces an electron flux density of 1013 to 1014 m−2 on the surface, and the short pulse minimizes the ionization time such that the resolution limit associated with a short drift tube is overcome. In addition, the injected 0.05 m3 quantitative sample reduces the vacuum exhaust load, and simultaneously, it is possible to temporarily form layers of the target molecules on the substrate. The possibility of immediate measurement by directly injecting benzene at ambient pressure was verified through repeated measurements; therefore, it is technically possible to use a CES to allow for a highly compact (and portable) TOF MS.
Coordination polymers for emerging molecular devices
Authors: Morritt G. H. , Michaels H. , Freitag M.
Published: February 2022

Conductive coordination polymers are hybrid materials with the potential to be implemented in the next generation of electronic devices, owing to several desirable properties. A decade ago, only a few scattered examples exhibiting conductivity existed within this class of materials, yet today groups of coordination polymers possess electrical conductivities and mobilities that rival those of inorganic semiconductors. Many currently emerging energy harvesting and storage technologies are limited by the use of inefficient, unstable, and unsustainable charge transport materials with little tunability. Coordination polymers, on the other hand, offer great electrical properties and fine-tunability through their assembly from molecular building blocks. Herein, the structure–function relationship of these building blocks and how to characterize the resulting materials are examined. Solution processability allows devices to step away drastically from conventional fabrication methods and enables cheap production from earth abundant materials. The ability to tune the electrical and structural properties through modifications at the molecular level during the material synthesis stages allows for a large design space, opening the door to a wide spectrum of applications in environmentally friendly technologies, such as molecular wires, photovoltaics, batteries, and sensors. Sustainable, high-performing charge transport materials are crucial for the continued advance of emerging molecular technologies. This review aims to provide examples of how the promising properties of coordination polymers have been exploited to accelerate the development of molecular devices.
Analytical solutions for nonionic and ionic diffusio-osmotic transport at soft and porous interfaces
Authors: Sivasankar Vishal Sankar , Prajapati Mihirkumar , Das Siddhartha
Published: February 2022

In this paper, we develop one of the first models for closed-form fully analytical solutions for describing the nonionic and ionic diffusio-osmotic (DOS) transport at interfaces grafted with a soft and porous polymeric film in the presence of a neutral solute concentration gradient (for nonionic diffusio-osmosis) and a salt concentration gradient (for ionic diffusio-osmosis). The nonionic DOS velocity depends on this solute concentration gradient and the drag force from the polymeric film. The ionic DOS transport is characterized by the diffusio-osmotically induced electric field and the diffusio-osmotically induced velocity field. This induced electric field is primarily dictated by the conduction of the mobile ion imbalance present within the electric double layer, induced at the charged solid, in the presence of the applied salt concentration gradient. The DOS velocity, on the other hand, is driven by a combination of the induced pressure gradient and an induced electro-osmotic body force (triggered by this induced electric field) and is opposed by the drag from the polymer layer. The result is a velocity field whose magnitude increases rapidly at near wall locations, decreases away from the wall, and depending on the salt concentration, may or may not increase outside the polymeric layer. This unique velocity profile ensures the presence of significant hydrodynamic shear stress across a wide zone extending from the wall in a non-confined fluidic system: This will ensure that finite-sized species (e.g., biological cells) can be conveniently made to access locations of large hydrodynamic stresses for a myriad of engineering and biological applications.
Modeling the wavelength of unresolved transition arrays in the extreme ultraviolet region from Sn to Hf ions by combining theoretical and experimental spectral data
Authors: Sasaki A. , Fujii K. , Murakami I. , Sakaue H. A. , Nishikawa T. , Ohashi H. , Nakamura N.
Published: February 2022

This paper proposes a method to determine the wavelength of unresolved transition arrays (UTAs) in the extreme ultraviolet (EUV) wavelength region from Sn to Hf plasma by combining calculated and experimental data. Based on a computational analysis of the atomic structure, we show that the wavelength of UTAs can be explained using the screening theory by a simple quadratic formula using the effective core charge and the screening constant for 4d electrons as parameters. The results from the model were compared with experiments to reproduce the trend of the spectrum, which has a minimum wavelength with respect to the ion charge. The wavelength is shown to agree with experiment over Pd- to Sr-like ions by applying a small shift that was determined using the spectrum observed in the electron beam ion trap. The present model would allow us to calculate the opacity of Sn plasmas with much smaller computational time than using present large-scale collisional radiative models, with fewer energy levels and parameterized rate coefficients, which will be also useful to investigate the efficiency of the EUV light source.
Dynamic surface patterns on cells
Authors: Chatterjee Mainak , Sain Anirban
Published: February 2022

Dynamic pattern formations are commonly observed in multicellular systems, such as cardiac tissue and slime molds, and modeled using reaction–diffusion systems. Recent experiments have revealed dynamic patterns in the concentration profile of various cortical proteins at a much smaller scale, namely, embryos at their single-cell stage. Spiral waves of Rho and F-actin proteins have been reported in Xenopus frog and starfish oocytes [Bement et al., Nat. Cell Biol. 17, 1471 (2015)], while a pulsatile pattern of Rho and myosin proteins has been found in C. elegans embryo [Nishikawa et al., eLife 6, e30537 (2017)]. Here, we propose that these two seemingly distinct dynamic patterns are signatures of a single reaction–diffusion network involving active-Rho, inactive-Rho, actin, and myosin. We show that a small variation in the concentration of other ancillary proteins can give rise to different dynamical states from the same chemical network.
Ionization waves (striations) in a low-current plasma column revisited with kinetic and fluid models
Authors: Boeuf J. P.
Published: February 2022

A one-dimensional particle-in-cell Monte Carlo collisions method has been used to model the development and propagation of ionization waves in neon and argon positive columns. Low-current conditions are considered, that is, conditions where stepwise ionization or Coulomb collisions are negligible (linear ionization rate). This self-consistent model describes the development of self-excited moving striations, reproduces many of the well-known experimental characteristics (wavelength, spatial resonances, potential drop over one striation, and electron “bunching” effect) of the ionization waves called p, r, and s waves in the literature, and sheds light on their physical properties and on the mechanisms responsible for their existence. These are the first fully kinetic self-consistent simulations over a large range of conditions reproducing the development of p, r, and s ionization waves. Although the spatial resonances and the detailed properties of the striations in the nonlinear regime are of kinetic nature, the conditions of existence of the instability can be obtained and understood from a linear stability analysis of a three-moment set of quasi-neutral fluid equations where the electron transport coefficients are expressed as a function of electron temperature and are obtained from solutions of a 0D Boltzmann equation. An essential aspect of the instability leading to the development of these striations is the non-Maxwellian nature of the electron energy distribution function in the uniform electric field prior to the instability onset, resulting in an electron diffusion coefficient in space much larger than the energy diffusion coefficient.
Line mixing in the oxygen B band head
Authors: Domysławska Jolanta , Wójtewicz Szymon , Bielska Katarzyna , Bilicki Sławomir , Ciuryło Roman , Lisak Daniel
Published: February 2022

We present the results of direct measurements of the line mixing parameters for two pairs of overlapping transitions at the band head of the oxygen B band. Measurements were performed with the frequency-stabilized cavity ring-down spectrometer assisted by an optical frequency comb. The recorded spectra were analyzed with line profiles comprising speed dependence, Dicke narrowing, and line mixing. Incorporation of the line mixing into the model eliminated previous discrepancies for pressure shift and their speed dependence coefficients. First-order line mixing was determined directly from the line shape fitting at relatively low pressure (0.04 atm) together with other line shape parameters and compared with that calculated by Sung et al. [J. Quant. Spectrosc. Radiat. Transfer 235, 232–243 (2019)].
Observation of the bubble-like morphology of atmospheric air plasma in two-phase flow of vaporizing water
Authors: Yu Mengjie , Peng Yang , Hou Zhongyu
Published: February 2022

The splitting and/or coalescing branched streamer network patterns are the most common settings of the atmospheric plasma. In this work, it is reported that a volumetric bubble cluster pattern can be realized in the interaction process of an atmospheric pressure diffuse plasma with a two-phase jet flow of superheated water. A new method using electric heating of a metallic tube filled with water is proposed to generate such a kind of vaporizing fluid. The plasma characteristics during the hydrodynamic process have been investigated by means of the high-speed Mach–Zehnder laser interferometry. The crucial feature of the morphology of plasmas, marked by the shifted fringes, has been enveloped with high contrast bright boundaries in both schlieren and shadowgraph photography, suggesting a critical phenomenon may exist in the heat and mass transfer process. The formation of the bubble-like morphology has induced higher electron density, and it is also found that the increase in the temperature during the jet flow and the increase in the discharge current are accompanied. The methodology exhibits the potential of applications relevant in the context of atmospheric diffuse plasma sources of high electron density and tunable chemistry of the neutral species.
Equations of state for single-component and multi-component multiphase lattice Boltzmann method
Authors: Baakeem Saleh S. , Bawazeer Saleh A. , Mohamad A. A.
Published: February 2022

The lattice Boltzmann method is an alternative method for conventional computational fluid dynamics. It has been used for simulating single-phase and multiphase flows and transport phenomena successfully and efficiently. In the current work, single-component and multi-component multiphase systems are studied. A methodology that differentiates between types of fluids is developed. Moreover, an approach for a multi-component multiphase system is developed in which a single distribution function is used regardless of the number of components. The value of the cohesion parameter (Gf) in the multi-component multiphase model becomes unimportant, like the cohesion parameter (Gp) in the single-component multiphase model, because their effects cancel when calculating the cohesion force. The fluids and mixtures are treated as real, so that mixing rules are used for the mixtures. Several types of fluids and mixtures are considered to investigate the capability of the proposed approach in dealing with miscible mixtures in both azeotrope and non-azeotrope situations. The layered Poiseuille flow and falling droplet on a liquid film are presented to evaluate the model developed. We conclude that this methodology can distinguish between different types of fluids when modeling single-component and multi-component multiphase systems.
Perspective on scalable high-energy-density polymer dielectrics with ultralow loadings of inorganic nanofillers
Authors: Li Li , Zhou Yao , Liu Yang , Chen Xin , Han Zhubing , Wang Qing
Published: February 2022

Polymer composite dielectrics have been actively developed for electrical power and electronic applications. The latest advances in dielectric polymer composites with ultralow (<1 vol. %) filler loadings have overcome many of the significant drawbacks of polymer composites. Such composites now offer opportunities of gleaning insights into the impact of interfaces on dielectric behaviors and developing dielectric mathematical theories and models with the interface contributions. In this Perspective, we review key developments in the dielectric polymer composites with ultralow contents of small-sized fillers. We highlight the filler–polymer interface characterizations and the current understandings of the underlying mechanisms and examine the dielectric models in order to fit the dielectric data over a wide range of filler contents. We also discuss challenges and opportunities for the polymer composites with ultralow filler loadings in the development of scalable high-energy-density dielectrics.
Transport coefficients of gel electrolytes: A molecular dynamics simulation study
Authors: Kiyohara Kenji , Tamura Minagi
Published: February 2022

The responses of gel electrolytes to stimuli make them useful in applications such as sensors and actuators. However, few studies have explored their transport properties from a molecular viewpoint. We studied the transport coefficients of gel electrolytes based on perfluorinated sulfonic acid using molecular dynamics simulations. The transport coefficients for electric and pressure fields, namely, the ionic conductivity, Darcy permeability, and cross coupling constant, were calculated based on Kubo’s linear response theory from the corresponding velocity correlation functions and mean square displacements. The effects of the water content of the gel electrolyte and those of the monovalent cationic species were also analyzed. The calculated transport coefficients qualitatively agree with the reported experimental results. The role of the cross coupling constants in determining the functional efficiency of gel electrolytes as pressure sensors or electroactive actuators is discussed.
Quantitative study of the control of hypersonic aerodynamics using millisecond pulsed discharges
Authors: Wang Hongyu , Min Fu , Xie Zhendong , Li Jie , Dai Jinwen , Yang Yanguang
Published: February 2022

The experimental study of the high-speed aerodynamic control using pulsed discharges is a fundamental yet relatively unexplored issue. This is because the strong electromagnetic interference (EMI) caused by these discharges can affect the accuracy of conventional measurements. A quantitative knowledge of this issue can help to evaluate the aerodynamic control capabilities of pulsed discharges. Therefore, in this study, a fiber-optic balance based on a Fabry–Pérot sensor, which is not subject to EMI, was applied to the acquisition of aerodynamic data with pulsed discharges in a Mach-6 flow. The pulsed discharges were characterized by a long pulse width of around 1 ms and a low frequency of 100 Hz. There was notable variation in the axial force under these pulsed discharges, which indicates their effectiveness for shock manipulation. In the presence of a pulsed discharge, fast-response Schlieren imaging revealed both shock-attenuation and thermal-choking effects in the aerodynamic control. The balance data indicate that the rate of axial-force reduction increases linearly with discharge pulse energy, but it decreases parabolically with increasing angle of attack.
Microwave calibration of qubit drive line components at millikelvin temperatures
Authors: Simbierowicz Slawomir , Monarkha Volodymyr Y. , Singh Suren , Messaoudi Nizar , Krantz Philip , Lake Russell E.
Published: February 2022

Systematic errors in qubit state preparation arise due to non-idealities in qubit control lines such as impedance mismatch. Using a data-based methodology of short-open-load calibration at a temperature of 30 mK, we report calibrated 1-port scattering parameter data of individual qubit drive line components. At 5 GHz, cryogenic return losses of a 20-dB-attenuator, a 10-dB-attenuator, a 230-mm-long 0.86-mm silver-plated cupronickel coaxial cable, and a 230-mm-long 0.86-mm NbTi coaxial cable were found to be 35−2+3 dB, 33−2+3 dB, 34−2+3 dB, and 29−1+2 dB, respectively. For the same frequency, we also extract cryogenic insertion losses of 0.99−0.04+0.04 dB and 0.02−0.04+0.04 dB for the coaxial cables. We interpret the results using master equation simulation of all XY gates performed on a single qubit. For example, we simulate a sequence of two 5 ns gate pulses (X and Y) through a two-element Fabry–Pérot cavity with 276-mm path length directly preceding the qubit and establish that the return loss of its reflective elements must be >9.7 dB (>14.7 dB) to obtain 99.9% (99.99%) gate fidelity.
Self-ordering and organization of in-line particle chain in a square microchannel
Authors: Liu Jiazheng , Pan Zhenhai
Published: February 2022

Precise determination of microfluidic behaviors is theoretically significant and has shown remarkable application prospects. This work numerically studies the self-ordering and organization of an in-line particle chain flowing through a square microchannel. The immersed boundary-lattice Boltzmann method is employed, and effects of particle Reynolds number (Rep), length fraction (⟨Lf⟩, characterizes particle concentration), and particle size are focused. Results imply a relatively complex migration of small-particle chains. Three typical states are observed, that is, the equilibrium position finally in a stabilized, fluctuated, or chaotic condition. The corresponding dynamic processes are presented. Interestingly, how interparticle spacing evolves with time shows similar regularity with the three states, corresponding to a particle chain either being evenly distributed, moving like a bouncing spring, or continuously in disordered motions. The flow field and force conditions are analyzed to clarify the mechanisms, suggesting the subtle interaction among vortex-induced repulsive force, wall-induced lift force, and shear gradient lift force is the reason behind. Based on different states, migratory patterns are categorized as Stable Pattern, Spring Pattern, and Chaotic Pattern, and an overall classification is also obtained. Moreover, effects of Rep and ⟨Lf⟩ are identified, where a rising Rep leads to an equilibrium position toward the wall and larger volatility of interparticle spacings. The dynamic characteristics are characterized by lagging, translational, and angular velocities of particles in the chain. Finally, a contrastive study of large particles is performed. The present investigation is expected to provide insight into regularities of in-line particle chains and possible applications.
Theoretical study of active secondary transport: Unexpected differences in molecular mechanisms for antiporters and symporters
Authors: Berlaga Alex , Kolomeisky Anatoly B.
Published: February 2022

Successful functioning of biological cells relies on efficient translocation of different materials across cellular membranes. An important part of this transportation system is membrane channels that are known as antiporters and symporters. They exploit the energy stored as a trans-membrane gradient of one type of molecules to transport the other types of molecules against their gradients. For symporters, the directions of both fluxes for driving and driven species coincide, while for antiporters, the fluxes move in opposite directions. There are surprising experimental observations that despite differing only by the direction of transport fluxes, the molecular mechanisms of translocation adopted by antiporters and symporters seem to be drastically different. We present chemical-kinetic models to quantitatively investigate this phenomenon. Our theoretical approach allows us to explain why antiporters mostly utilize a single-site transportation when only one molecule of any type might be associated with the channel. At the same time, the transport in symporters requires two molecules of different types to be simultaneously associated with the channel. In addition, we investigate the kinetic constraints and efficiency of symporters and compare them with the same properties of antiporters. Our theoretical analysis clarifies some important physical–chemical features of cellular trans-membrane transport.
Reversible target-binding kinetics of multiple impatient particles
Authors: Grebenkov Denis S. , Kumar Aanjaneya
Published: February 2022

Certain biochemical reactions can only be triggered after binding a sufficient number of particles to a specific target region such as an enzyme or a protein sensor. We investigate the distribution of the reaction time, i.e., the first instance when all independently diffusing particles are bound to the target. When each particle binds irreversibly, this is equivalent to the first-passage time of the slowest (last) particle. In turn, reversible binding to the target renders the problem much more challenging and drastically changes the distribution of the reaction time. We derive the exact solution of this problem and investigate the short-time and long-time asymptotic behaviors of the reaction time probability density. We also analyze how the mean reaction time depends on the unbinding rate and the number of particles. Our exact and asymptotic solutions are compared to Monte Carlo simulations.
A
Authors: Cao Guan-hua , Wang Xi-fu , Li Ze-dong , Zhang Xue , Li Xiao-gang , Gu Wen , Zhang Fan , Yu Jie , He Sen
Published: February 2022

The crisis of arsenic (As) accumulation in rhizomes threatens the quality and safety of Panax notoginseng(Burk.) F.H. Chen, which is a well-known traditional Chinese herb with a long clinical history. The uptake of arsenate (AsV) could be suppressed by supplying phosphate (Pi), in which Pi transporters play important roles in the uptake of Pi and AsV. Herein, the P. notoginseng Pi transporter-encoding gene PnPht1;3 was identified and characterised under Pi deficiency and AsV exposure. In this study, the open reading frame (ORF) of PnPht1;3 was cloned according to RNA-seq and encoded 545 amino acids. The relative expression levels revealed that PnPht1;3 was significantly upregulated under phosphate deficiency and AsV exposure. Heterologous expression in Saccharomyces cerevisiae MB192 demonstrated that PnPht1;3 performed optimally in complementing the yeast Pi-transport defect and accumulated more As in the cells. Combined with the subcellular localisation prediction, it was concluded that PnPht1;3 encodes a functional plasma membrane-localised transporter protein that mediates putative high-affinity Pi/H+ symport activity and enhances the uptake of Pi and AsV. Therefore, a better understanding of the roles of the P. notoginseng Pi transporter could provide new insight for solving As accumulation in medicinal plants.
iASPP suppresses Gp78-mediated TMCO1 degradation to maintain Ca
2+
homeostasis and control tumor growth and drug resistance
Authors: Zheng Shanliang , Zhao Dong , Hou Guixue , Zhao Song , Zhang Wenxin , Wang Xingwen , Li Li , Lin Liang , Tang Tie-Shan , Hu Ying
Published: February 2022

Significance

Accumulating preclinical and clinical evidence has supported a central role for alterations in Ca
2+
homeostasis in the development of cancer. TMCO1 protein is an identified Ca
2+
-channel protein, while its roles in cancer remain obscure. Here, we found that TMCO1 is increased in colon cancer tissues. In addition, it is a substrate of E3 ligase Gp78. Enhanced oncogene iASPP stabilizes TMCO1 by competitively binding with Gp78. Inhibition of iASPP-TMCO1 sensitizes cancer cells’ response to Ca
2+
-induced apoptosis. This study has improved our fundamental understanding of the Ca
2+
homeostasis in cancer cells. iASPP-TMCO1 axis may present a promising therapeutic target that can combine the conventional drugs to reinforce Ca
2+
-dependent apoptosis.
Toward a theory of evolution as multilevel learning
Authors: Vanchurin Vitaly , Wolf Yuri I. , Katsnelson Mikhail I. , Koonin Eugene V.
Published: February 2022

Significance

Modern evolutionary theory gives a detailed quantitative description of microevolutionary processes that occur within evolving populations of organisms, but evolutionary transitions and emergence of multiple levels of complexity remain poorly understood. Here, we establish the correspondence among the key features of evolution, learning dynamics, and renormalizability of physical theories to outline a theory of evolution that strives to incorporate all evolutionary processes within a unified mathematical framework of the theory of learning. According to this theory, for example, replication of genetic material and natural selection readily emerge from the learning dynamics, and in sufficiently complex systems, the same learning phenomena occur on multiple levels or on different scales, similar to the case of renormalizable physical theories.
IKKα-deficient lung adenocarcinomas generate an immunosuppressive microenvironment by overproducing Treg-inducing cytokines
Authors: Song Na-Young , Li Xin , Ma Buyong , Willette-Brown Jami , Zhu Feng , Jiang Chengfei , Su Ling , Shetty Jyoti , Zhao Yongmei , Shi Gongping , Banerjee Sayantan , Wu Xiaolin , Tran Bao , Nussinov Ruth , Karin Michael , Hu Yinling
Published: February 2022

Significance

This study reveals that impaired IKKα expression or activity in lung cancer enhances differentiation of protumorigenic Treg cells through a TNF/TNFR2/NF-κB signaling pathway in both human and mouse lung ADC. Depletion of one of the molecules that are required for Treg cell induction represses lung ADC development. Thus, the components that interfere with this particular Treg differentiation provide targets for the generation of TME-modifying therapies.
Highly stabilized delay optical path with a long fiber toward absolute distance measurement
Authors: Gao Haoran , Long Xiefen , Jin Xueying , Xu Xin , Lu Yang , Bian Dian , Yu Liandong
Published: February 2022

A stabilized delay optical path (DOP) toward absolute distance measurement is proposed based on the principle of optical balanced cross-correlation (OBCC). An OBCC signal is a subtraction from two-second harmonics generated by a periodically polarized crystal when the fundamental frequency pulses pass through periodically polarized crystal twice from the front and back. The steep slope of signal near the zero point is 67 mV nm−1 and is used to lock the fiber stretcher in the DOP by a servo controller. Thereby the purpose of stabilizing the DOP has been completed. The DOP is composed of a long fiber with two different applied lengths of ∼466 and ∼2000 m. The pulse numbers difference between delay and reference fibers are 227 and 978. The long-term repeatability of measurement deviations is 1.6 μm and 2.9 μm over 10 min, respectively. Therefore, this highly stabilized DOP can be considered as a stable device of the optical path.
Green synthesis of MnxZn(1−x)O nanostructure using Azadirachta indica leaf extract and its microstructural and optical study
Authors: Barman Subhodeep , Sikdar Suranjan , Biswas Abhijit , Islam Anikul , Das Rahul
Published: February 2022

Zinc Oxide (ZnO) nanostructures doped with manganese (Mn: 5% and 10%) were prepared by the green synthesis method using the leaf extracts of Azadirachta indica. The microstructural investigation of the prepared nanopowders was carried out with the Rietveld refinement of the x-ray diffraction data. The phase analysis of the x-ray diffraction data confirmed that the synthesized nanoparticles have the hexagonal wurtzite structure in all cases. The Williamson Hall method was used to analyze the data obtained after the Rietveld refinement analysis to find some important microstructural parameters such as crystallite size, strain, stress, and energy density. The size of the crystallites is almost the same in both cases and the values for strain, stress, and energy density increase with increasing Mn concentration. Functional groups and molecular interactions were identified by the Fourier Transform Infra-Red spectroscopy spectra. UV-visible spectra show that the bandgap energy decreases with increasing Mn content. This property can help to fabricate a photodetector that can operate at a wavelength longer than the cut-off wavelength of ZnO. The morphology of the synthesized nanostructure was studied by field emission scanning electron microscope. The energy dispersive x-ray spectroscopy data confirm the elemental compositions in the synthesized Mn-doped ZnO, which means that the desired nanostructures were successfully synthesized by the green method.
Effect of chromium substitution on the electrical and magnetic properties of multiferroic yttrium manganite
Authors: Sivaraj K S , Thoufeeq S , Anantharaman M R
Published: February 2022

Yttrium Manganite is a multiferroic material and has potential applications in Ferroelectric Random Access Memories. Chromium is substituted with a view to enhancing the electrical conductivity. Compositions belonging to the series Y1−xCrxMnO3, (x = 0, 0.05, 0.1, and 0.3) were synthesized by employing a citrate gel method. Pre characterized samples using X-ray diffraction and Scanning Electron Microscopy were then subjected to impedance spectroscopy to understand the conduction mechanism vis-à-vis small polaron hopping or variable range hopping. Cole-Cole and Nyquist plots were utilized to arrive at the equivalent circuit. Ferroelectric measurements were carried out to understand the polarization mechanisms. Magnetic measurements were also conducted to observe the change in magnetic properties with Chromium substitution. Field Cooled (FC) and Zero Field Cooled (ZFC) magnetization measurements revealed the presence of ferromagnetic clusters in an antiferromagnetic matrix. It has been found that Chromium substitution enhances the electrical conductivity while it diminishes the ferroelectric properties.
Light bending by the cosmological constant
Authors: Hu Lingyi , Heavens Alan , Bacon David
Published: February 2022

We revisit the question of whether the cosmological constant Λ affects the cosmological gravitational bending of light, by numerical integration of the geodesic equations for a Swiss cheese model consisting of a point mass and a compensated vacuole, in a Friedmann-Robertson-Walker background. We find that there is virtually no dependence of the light bending on the cosmological constant that is not already accounted for in the angular diameter distances of the standard lensing equations, plus small modifications that arise because the bending is restricted to a finite region covered by the hole. The residual Λ dependence for a 1013
M
☉ lens is at the level of 1 part in 107, and even this might be accounted for by small changes in the hole size evolution as the photon crosses. We therefore conclude that there is no need for modification of the standard cosmological lensing equations in the presence of a cosmological constant.
Beyond rates: time-varying dynamics of high frequency oscillations as a biomarker of the seizure onset zone
Authors: Nunez Michael D , Charupanit Krit , Sen-Gupta Indranil , Lopour Beth A , Lin Jack J
Published: February 2022

Objective. High frequency oscillations (HFOs) recorded by intracranial electrodes have generated excitement for their potential to help localize epileptic tissue for surgical resection. However, the number of HFOs per minute (i.e. the HFO ‘rate’) is not stable over the duration of intracranial recordings; for example, the rate of HFOs increases during periods of slow-wave sleep. Moreover, HFOs that are predictive of epileptic tissue may occur in oscillatory patterns due to phase coupling with lower frequencies. Therefore, we sought to further characterize between-seizure (i.e. ‘interictal’) HFO dynamics both within and outside the seizure onset zone (SOZ). Approach. Using long-term intracranial EEG (mean duration 10.3 h) from 16 patients, we automatically detected HFOs using a new algorithm. We then fit a hierarchical negative binomial model to the HFO counts. To account for differences in HFO dynamics and rates between sleep and wakefulness, we also fit a mixture model to the same data that included the ability to switch between two discrete brain states that were automatically determined during the fitting process. The ability to predict the SOZ by model parameters describing HFO dynamics (i.e. clumping coefficients and coefficients of variation) was assessed using receiver operating characteristic curves. Main results. Parameters that described HFO dynamics were predictive of SOZ. In fact, these parameters were found to be more consistently predictive than HFO rate. Using concurrent scalp EEG in two patients, we show that the model-found brain states corresponded to (1) non-REM sleep and (2) awake and rapid eye movement sleep. However the brain state most likely corresponding to slow-wave sleep in the second model improved SOZ prediction compared to the first model for only some patients. Significance. This work suggests that delineation of SOZ with interictal data can be improved by the inclusion of time-varying HFO dynamics.
Development of activated carbon-doped TiO2 nanoparticle thin film for application in dye-sensitized solar cells
Authors: lunphut Sumneang
Published: February 2022

Carbon This research aims to study the preparation of activated carbon-doped TiO2 nanoparticle thin films with basellaceae, malvaceae and hylocereus dyes for application in dye-sensitized solar cells (DSSCs). The physical and chemical properties of as-prepared thin films were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-vis diffuse reflectance spectra (UV-vis DRS) techniques. Results revealed that the basellaceae dye (JSC is 13.5 mA/cm2, VOC is 0.450 V and η (%) is 1.59) on thin film showed the highest efficiency compared with the malvaceae (JSC is 10.2 mA/cm2, VOC is 0.425 V and η (%) is 1.08) and hylocereus (JSC is 12.1 mA/cm2, VOC is 0.325 V and η (%) is 1.17) dyes. Moreover, we observed that activated carbon/TiO2 nanoparticle thin film exhibited a higher efficiency than other thin film samples. This might be due to the activated carbon doped into the TiO2 leading to facilitate the separation of photogenerated charge carriers, resulting in its enhanced efficiency.
Performance of CsI (Tl) photodiode with optic fiber wire for Gamma-rays and X-rays detection
Authors: Aim-O Pawitra , Klinkhieo Supat , Sophon Methee , Sumano Nattaphol , Phacheerak Wiwek , Phanak Mongkol , Ruangvittayanon Anuchit
Published: February 2022

In this paper, we explored the feasibility study of using the optic fiber wire to be a light transmitter for crystal scintillation material in the radiation measurement. The high-density material; thallium doped cesium iodide CsI (Tl) are widely used as converters for Gamma-rays and X-rays into visible light. Optic fibers are applied in the various applications such nuclear facilities, future fusion installations, medical treatment and diagnostic premises etc. The major advantages to be considered in optic fibers for radiation detection because their characteristics such as: capacities to work under electromagnetic fields; possibility to carry the wavelength signals; small size and low mass including possibility to monitor parameters from the sites far away from the controller. In this work, the cylindrical crystal CsI (Tl) material was connected with the single-clad optic scintillating fiber which transmitted the light signal to photodiode. Gamma-rays and X-rays sources had been investigated the measurement. The optic scintillating fibers have a good response with Cs-137 gamma radiation source at 662 keV. X-ray radiation that was generated from the X-ray tube was determined with the different operating voltages. The obtained results show this device can measure the X-ray radiation with energy range from 39 to 309 keV. CsI (TI) photodiode detector with optic fiber wire can be applied to measure gamma radiation and X-ray radiation as well as being able to the further work in the nuclear and radiation fields.
Characterization of deposited Ti-doped lithium aluminium hydride thin film using dip coating method
Authors: Chowarot C. , Siriwongrungsona V. , Hongrapipat J. , Pang S. , Messner M.
Published: February 2022

Lithium aluminium hydride (LiAlH4) is an outstanding complex metal hydride as a hydrogen storage material. The hydrogen storage capacity of LiAlH4 is about 5-7 wt%. In this study, LiAlH4 concentration of 20 g/l doped with various titanium (Ti) concentration by dip coating method was examined. The titanium dioxide (TiO2) powder at 10 mol % 25 mol % and 40 mol % was used as the Ti source. Instruments used to analyze Ti-doped LiAlH4 were X-ray powder diffraction (XRD) and scanning electron microscope (SEM). XRD was used for phase and crystallite size analysis and SEM was used for surface morphology investigation. The experimental results reveal that at the LiAlH4 concentration of 20 g/l with 40 mol% of TiO2, the smallest crystallite size with rather dense surface was shown. The small crystallite size can improve the desorption of hydrogen from its surface area. Therefore, the addition of titanium might be advantageous in improving the hydrogen storage efficiency of LiAlH4.
Effect of Silk Fibroin Content on Physical and Mechanical Properties of Electrospun Poly(lactic acid)/Silk Fibroin Nanofibers for Meniscus Tissue Engineering Scaffold
Authors: Promnil Siripanyo , Ruksakulpiwat Yupaporn , Ruksakulpiwat Chaiwat , Numpaisal Piya-on
Published: February 2022

This study aims to produce composite nanofibers from polylactic acid (PLA) and silk fibroin (SF) with mechanical properties similar to that of a native meniscus. SF is a natural protein, well known for its good biocompatibility and biodegradability but it has poor mechanical properties compared to synthetic polymers. SF contains proteins which can promote cell adhesion and cell proliferation required for a tissue engineering scaffold. PLA is a popular material that is widely used in tissue engineering. It provides high mechanical properties but lacks bioactivity and cell affinity. Thus, a PLA/SF composite scaffold can improve these drawbacks. In this study, PLA/SF nanofibers were fabricated using an electrospinning process at various PLA and SF ratios (PLA: SF 100:0, 75:25, 50:50, and 25:75). The SF content in the emulsion dominated the fiber diameter, fiber arrangement and processibility of nanofibrous scaffold. With increasing SF content, the %elongation at break of PLA/SF scaffold increased but Young’s modulus decreased. The wettability of electrospun PLA was increased with an increase in SF content.