bluuebunny/crossref_metadata_2025 huggingface dataset:
New Technology of Thermoplastic Coating for Osmotic Pump Tablets: Study on in vitro Drug Release
Authors: Yuan Chunping , Hou Huimin , Ou Shuyun , Zhao Shujing , Gao Yongjian , Liu Qing
Published: August 2019

Aim The in vitro drug release profiles of metformin hydrochloride thermoplastic coated tablets and nifedipine thermoplastic coated tablets were studied.

Methods By measuring the in vitro release profiles of the thermoplastic coated tablets of model drugs, the effects of membrane thickness, polyethylene glycol-1,500 (PEG1500) content, number of orifice, stirring speed, and release medium on the drug release were investigated, and the rule and mechanism of drug release were also analyzed by comparing with the osmotic pump tablets (OPTs).

Results Thermoplastic coated tablets with single- or double-chamber construction performed the same function of controlling the drug release, operated under the same release mechanism (osmotic pressure drove the drug release), and exhibited the same release characteristics (zero-order release, unaffected by release medium, and stirring speed) and release rule (release rate was inversely proportional to the membrane thickness but proportional to the PEG1500 content) as compared with OPTs prepared by the common spray coating technology.

Conclusion Thermoplastic coated tablets have the same release characteristics in vitro as OPTs. The new technology of thermoplastic coating can replace the spray coating technology of OPTs. This study provides theoretical basis and practical support for the industrialization and clinical application of thermoplastic coating technology.
X-ray sources using a picosecond laser driven plasma accelerator
Authors: Lemos N. , King P. , Shaw J. L. , Milder A. L. , Marsh K. A. , Pak A. , Pollock B. B. , Goyon C. , Schumaker W. , Saunders A. M. , Papp D. , Polanek R. , Ralph J. E. , Park J. , Tommasini R. , Williams G. J. , Chen Hui , Hartemann F. V. , Wu S. Q. , Glenzer S. H. , Hegelich B. M. , Moody J. , Michel P. , Joshi C. , Albert F.
Published: August 2019

Laser-plasma-based accelerators are now able to provide the scientific community with novel high-energy light sources that are essential to study high-energy density matter, inertial confinement fusion, astrophysical systems, and fundamental plasma physics. Due to the transient and high-density properties of these systems, it is essential to develop light sources that are in the hard x-ray energy range (0.01–1 MeV) and directional and have high yield, low divergence, and short duration (ps and sub-ps). In this work, we show that by using a Laser plasma accelerator, it is possible to generate a broadband (0.01–1 MeV) hard x-ray source that satisfies the previous requirements. A series of experiments were conducted on the Titan laser at the Lawrence Livermore National Laboratory where a 10 nC electron beam in the 10–380 MeV energy range was generated through a laser plasma accelerator. The electrons generate x-rays via their betatron motion (few-30 keV) and hard x-rays through inverse Compton scattering (10–250 keV) and/or Bremsstrahlung (up to 1 MeV). Due to its unique characteristics, this source can be an important tool for many applications in large-scale international laser facilities.
Defect-rich GaN interlayer facilitating the annihilation of threading dislocations in polar GaN crystals grown on (0001)-oriented sapphire substrates
Authors: Barchuk M. , Motylenko M. , Schneider T. , Förste M. , Röder C. , Davydok A. , Lazarev S. , Schimpf C. , Wüstefeld C. , Pätzold O. , Rafaja D.
Published: August 2019

The interaction of microstructure defects is regarded as a possible tool for the reduction of the defect density and improvement of the crystal quality. In this study, this general approach is applied to reduce the density of threading dislocations in GaN crystals grown using high-temperature vapor phase epitaxy directly on (0001)-oriented sapphire substrates. The GaN crystals under study were deposited in three steps with different process temperatures, growth rates, and ammonia flows. The first GaN layer accommodates the lattice misfit between sapphire and gallium nitride. Thus, it contains a high number of randomly distributed threading dislocations. The next GaN layer, which is internally structured and defect-rich, bends and bunches these dislocations and facilitates their annihilation. The uppermost GaN layer mainly contains bunched threading dislocations terminating large areas of almost defect-free GaN. In order to be able to visualize and to quantify the microstructure changes in individual parts of the sandwich-like structure, the samples were investigated using nanofocused synchrotron diffraction, confocal micro-Raman spectroscopy, and transmission electron microscopy. The transmission electron microscopy provided information about the kind of microstructure defects and their mutual interaction. The synchrotron diffraction and the micro-Raman spectroscopy revealed the depth profiles of dislocation density and lattice parameters.
Fabrication of the laser textured nickel surface and its tribological property under the water lubrication
Authors: Huang Junyuan , Zhang Lixin , Wei Songbo , Yang Yingying , Yang Song , Shen Zejun
Published: August 2019

Friction is one of the main causes of mechanical component failure and material waste. It is known from the friction theory that changing the roughness of the surface of the material can change the friction property of the material. Laser surface texturing is a good method for constructing a rough surface. In the experiment, the texture of the circular pits with different areal densities was constructed on the nickel surface. The coefficient of friction of the circular pit under the water-lubricated friction condition was kept at about 0.17, while the untreated metal nickel under the same conditions exceeds 0.65. The circular pit texture improves the frictional properties of the nickel surface.
AC electrokinetic induced non-Newtonian electrothermal blood flow in 3D microfluidic biosensor with ring electrodes for point-of-care diagnostics
Authors: Ren Qinlong , Wang Yichao , Lin Xixiang , Chan Cho Lik
Published: August 2019

Efficient pumping of whole blood is an essential task in biomedical engineering, especially for point-of-care diagnostics using lab-on-a-chip devices. Alternating current (AC) electrokinetics have been widely used for several different applications among which pumping fluids using the precisely controlled electric field without any moving mechanical parts is significant. Due to its high conductive characteristic, it is difficult to drive the blood flow using the AC electroosmosis phenomenon because the electric double layer is highly compressed. Fortunately, the AC electrothermal (ACET) phenomenon occurs due to the variation of temperature-dependent permittivity and conductivity caused by Joule heating effects or other heat sources making it powerful for driving high electrical conductivity physiological fluids in biomedical devices. Compared with Newtonian fluids like saline solutions or urine, the non-Newtonian rheological nature and AC frequency-dependent dielectric property of blood make its ACET driving mechanism more complicated and attractive. In this paper, ACET induced blood flow in the 3D microfluidic channel is modeled by the lattice Boltzmann method accelerated using graphics processor units. The Carreau-Yasuda model is applied to simulate the shear-thinning behavior of blood flow, and its electrothermal pumping efficiency is investigated with respect to the AC electrode configuration, AC voltage magnitude, and AC signal frequency by comparing it with the ACET pumping of Newtonian fluids using scaling law analysis. The results demonstrate that the ACET phenomenon is effective for pumping non-Newtonian whole blood flow in microfluidic devices with ring electrodes which will contribute to the point-of-care diagnostic of bacterial bloodstream infections or rapid detection of circulating tumor cells.
Riemann problem for the isentropic Chaplygin gas Cargo-LeRoux model
Authors: Cheng Hongjun
Published: August 2019

The so-called Cargo-LeRoux model is a hyperbolic system of conservation laws derived from the Euler equations with a constant gravity. This paper is concerned with such a model for an isentropic Chaplygin gas. The Riemann problem is solved with four kinds of structures. The first is composed of the contact discontinuities, the second contains an overcompressible δ-wave (δ-shock wave), and the third and fourth involve a contact discontinuity and a kind of non-overcompressible δ-wave. One of the highlights of this paper lies in the introduction of the non-overcompressible δ-waves.
Phonon invisibility driven by strong magneto-elastic coupling in AlFeO3 thin film
Authors: Tyagi Shekhar , Sharma Gaurav , Choudhary R. J. , Sathe Vasant G.
Published: August 2019

Thin films of a lead-free magnetoelectric compound AlFeO3 have been deposited using a pulsed laser deposition technique. X-ray diffraction, X-ray absorption spectroscopy, and reflectivity measurements established the orthorhombic structure and a material density of 4.5 g/cm3, which is comparable to the bulk AlFeO3. The polycrystalline AlFeO3 film showed a strong magnetoelastic coupling. The Raman study carried out at variable temperatures and under an applied magnetic field at room temperature showed spectacular results. One of the Raman modes corresponding to AlFeO3 was found to vanish completely when the magnetic field of 0.08 T was applied at room temperature. The mode was also found to vanish between the temperature window of 280 K–236 K in temperature dependent studies. The observation was further supported by the detailed analysis of magnetization studies, which showed a change in the magnetic order in the same temperature interval. The invisibility of the Raman phonon mode has been attributed to the lattice deformation caused by the magnetoelastic effect. Additionally, the phonon frequencies showed renormalization below 200 K demonstrating a strong spin-lattice coupling.
Ambipolar Seebeck power generator based on topological insulator surfaces
Authors: Chiba Takahiro , Takahashi Saburo , Komine Takashi
Published: August 2019

We propose a thermoelectric (TE) energy conversion device based on the surface of a three-dimensional topological insulator (TI) that is magnetically gap-opened and ionically disordered. A pair of top and bottom surfaces of a single TI film takes the role of a vertical p–n junction with ambipolar conduction, which can be considered as a TE module consisting of two dissimilar TE materials. By tuning the surface carrier screening by means of electric gating, we find that the figure of merit ZT of the device exceeds 1 in the low-temperature-regime below 300 K. Our model may represent one direction for the implementation of TE energy conversion and heat management in nanodevices.
Accurate modeling of Knudsen diffusion in nanopores using a physical-based boundary model
Authors: Liang Tengfei , Li Qi
Published: August 2019

Gas transport in nanopores plays an important role in modern industry, such as shale gas exploitation, sea water desalination, fuel battery, etc. Owing to the small pore size, gas transport in nanopores is dominated by Knudsen diffusion, where the gas molecular motion is fully determined by the gas-surface interaction at the boundary. Classic theories of Knudsen diffusion, such as the “Smoluchowski model” and “extended Smoluchowski model”, were developed based on empirical gas-surface interaction models. These empirical boundary models may not be accurate to capture the key mechanism of Knudsen diffusion, particularly when the surface roughness is small, such as the case of carbon nanotubes. In this work, the influence of the empirical boundary models on Knudsen diffusion is studied in detail. Theoretical analysis indicates that the Knudsen diffusivity in one-dimensional pores critically depends on the correlation between gas molecular scattering angles on the pore surface. Benchmarked by molecular dynamics simulations, empirical boundary models show notable errors in the prediction of the scattering angle correlation, despite the fact that the accurate tangential momentum accommodation coefficient is used. In contrast, the physical-based boundary model, developed recently by our group, can accurately and efficiently reproduce the molecular dynamics simulation results. Its performance is further demonstrated in the modeling of the Knudsen diffusivity in a one-dimensional cylindrical pore, which predicts more accurate results than the Smoluchowski model and extended Smoluchowski model.
Fluorescence microscopy of biophysical protein dynamics in nanoporous hydrogels
Authors: Saini Anuj , Kisley Lydia
Published: August 2019

Proteins within nanoporous hydrogels have important biotechnological applications in pharmaceutical purification, tissue engineering, water treatment, biosensors, and medical implants. Yet, oftentimes proteins that are functional in solution lose activity when in contact with soft, nanostructured, condensed phase materials due to perturbations in the folded state, conformation, diffusion, and adsorption dynamics of the protein by the material. Fluorescence microscopy experimentally measures the biophysical dynamics of proteins within hydrogels at the nanoscale and can overcome the limitations of conventional ensemble techniques. An explanation of the benefits of fluorescence is provided, and principles of fluorescence microscope instrumentation and analysis are discussed. Then several nanoscale fluorescence microscopies that image nanoscale protein dynamics within hydrogels are introduced. First, location-based super-resolution imaging resolves the adsorption kinetics of proteins to charged ligands within hydrogels used in pharmaceutical separations. Next, correlation-based super-resolution techniques image the heterogeneity of the nanoscale pore size of the hydrogels and the diffusion of analytes within the pores simultaneously. Finally, fluorescence resonance energy transfer imaging combined with temperature jump perturbations determines the folding and stability of a protein within hydrogels. A common finding with all three fluorescence microscopies is that heterogeneous nanoporous hydrogel materials cause variability of protein behavior dependent on gel sterics and/or interfacial electrostatic forces. Overall, in situ observations of proteins in hydrogels using fluorescence microscopies can inform and inspire soft nanomaterial design to improve the performance, shelf life, and cost of biomaterials.
Mobile obstacles accelerate and inhibit the bundle formation in two-patch colloidal particle
Authors: Malhotra I. , Babu S. B.
Published: August 2019

Aggregation of protein into bundles is responsible for many neurodegenerative diseases. In this work, we show how two-patch colloidal particles self-assemble into chains and a sudden transition to bundles takes place by tuning the patch size and solvent condition. We study the kinetics of formation of chains, bundles, and networklike structures using patchy Brownian cluster dynamics. We also analyze the ways to inhibit and accelerate the formation of these bundles. We show that in the presence of inert immobile obstacles, the kinetics of formation of bundles slows down. However, in the presence of mobile aggregating particles, which exhibit interspecies hard sphere repulsion and intraspecies attraction, the kinetics of bundle formation accelerates slightly. We also show that if we introduce mobile obstacles, which exhibit interspecies attraction and intraspecies hard sphere repulsion, the kinetics of formation of bundles is inhibited. This is similar to the inhibitory effect of peptide P4 on the formation of insulin fibers. We are providing a model of mobile obstacles undergoing directional interactions to inhibit the formation of bundles.
Correlation of cation deficiency and nanostructure to decreased magnetism in a ferroelectric BiMnO3 film
Authors: Pajerowski Daniel M. , Krayer Lisa A. , Jeen Hyoungjeen , Borchers Julie A. , Biswas Amlan , Ravel Bruce
Published: August 2019

The pseudoperovskite BiMnO3 is a multiferroic candidate, but missing details of materials properties are impeding potential technological applications. BiMnO3 has a centrosymmetric structure that precludes ferroelectricity in bulk stoichiometric samples, while some films have reported ferroelectricity along with a decreased magnetic response. This puzzle motivated a study of one such film, deposited by pulsed laser deposition onto SrTiO3. Probes utilized include microscopy, diffraction, reflectometry, and X-ray absorption. These experiments in the context of the existing literature show an anomalous unit-cell volume and a (magnetic) depth profile. Then, the resulting inhomogeneous deficiency of Bi and Mn metals may stabilize a multiphase system that explains the decreased magnetism. Film nanostructure and strain effects are also considered.
Particle and rigidized red blood cell concentration distributions in microchannel flows
Authors: Tatsumi Kazuya , Noguchi Shinnosuke , Tatsumi Akira , Kuriyama Reiko , Nakabe Kazuyoshi
Published: August 2019

The motion and concentration distribution of particles and cells in flow are important factors which affect the fluid properties, flow structure, and mass transfer of biological and chemical species in blood vessels and channels. In this study, number density distributions of particles and rigidized red blood cells (RBCs) in a microchannel whose size is comparable to the sizes of the particle and RBCs are measured. Measurements were conducted at several streamwise locations for suspensions of particles and RBCs with hematocrits of the order of 10% and particle sizes of 5 and 8 µm. Analysis of the migration and resulting concentration distribution of the particles and RBCs was conducted using a model that considers the particle–particle collision and fluid dynamic force. As the size of the microchannel is small, the wall effect on the collision and migration of the particles and RBCs was significant. The wall reduced the overlapping area of the particles in collision and their displacement after collision (mobility), which varied the number, location, and magnitude of the maximum peaks observed in the number density distribution. Furthermore, the rotational motion of the rigidized RBCs in the channel flow reduced the effective lengths of the overlapping area and displacement, whereas it produced additional migration at the wall. With these terms added in the model, the number density distributions of the particles and RBCs showed reasonable agreement with those of the measurement. Especially, the number of peaks and their location for the maximum values in the model and measurement matched well.
Opacity effects on laser-produced plasma radiation sources
Authors: Tallents G. J.
Published: August 2019

The escape of spectral line radiation from laser-produced plasma radiation sources with moderate opacity is examined using a simple model of emission with a planar geometry, constant source function, and an empirically determined optical depth. The model is applied to determine the radiation produced by laser irradiation of tin targets used as the source of radiation in extreme ultraviolet (EUV) lithography. Variations in emission relative to optically thin plasmas in agreement with previous experimental measurements of both the angular variation of the emission of EUV light at 13.5 nm and the effect of plasma opacity in reducing EUV emission at laser intensities above 1011 W cm−2 are found. The model is extended to predict optimum conditions for future lithography radiation sources at ≈6.7 nm.
Cylindrical flowing-junction cell for the investigation of fluctuations and pattern-formation in miscible fluids
Authors: Croccolo Fabrizio , Brogioli Doriano , Vailati Alberto
Published: August 2019

We describe a flowing-junction cell with cylindrical symmetry suitable to investigate fluctuations and pattern formation at the diffusing interface between two miscible phases of a liquid mixture. The continuous outflow of the remixed fluid through a thin slit located at the midheight of the sample allows the preparation of an initially sharp interface. The system can be used in both gravity-stable and unstable conditions. In the stable case, the denser liquid is on the bottom of the cell and mass diffusion is the only active process for remixing the two liquids. Once the flow is stopped, one can investigate nonequilibrium fluctuations during free-diffusion in a binary mixture or double diffusive instabilities in multicomponent mixtures. Two horizontal transparent windows allow vertical mapping of the fluid flow by using shadowgraphy. In the unstable condition, with the denser fluid on top, stopping the radial flow at the interface gives rise to a Rayleigh-Taylor instability, which drives the denser liquid toward the bottom of the cell. The fact that the cell can maintain the system in the unstable condition shows that it is suitable to perform experiments under microgravity conditions. With respect to other free-diffusion cells, the proposed configuration has the advantage that the interface is extremely stable and flat, and that the experiments can be repeated by just flowing the cell with fresh liquids.
Suppressed-Doppler slit jet infrared spectroscopy of astrochemically relevant cations: ν1 and ν4 NH stretching modes in NH3D+
Authors: Scrape Preston G. , Chang Chih-Hsuan , Nesbitt David J.
Published: August 2019

A suppressed-Doppler (Δν = 180 MHz) infrared spectrum of monodeuterated ammonium ions (NH3D+) has been obtained for the ν1 (symmetric) and ν4 (degenerate) N–H stretch bands via direct absorption high resolution IR laser spectroscopy in a planar slit jet discharge expansion. The ion is efficiently generated by H3+ protonation of NH2D in a discharge mixture of H2/NH2D, with the resulting expansion rapidly cooling the molecular ions into low rotational states. The first high-resolution infrared spectrum of ν1 is reported, as well as many previously unobserved transitions in the ν4 rovibrational manifold. Simultaneous observation of both ν1 and ν4 permits elucidation of both the vibrational ground and excited state properties of the ion, including rigorous benchmarking of band origins against high-level anharmonic ab initio theory as well as determination of the ν1:ν4 intensity ratio for comparison with bond-dipole model predictions. Ground-state combination differences from this work and earlier studies permit the rotational constants of NH3D+ to be determined to unprecedented accuracy, the results of which support previous laboratory and astronomical assignment of the 10–00 pure rotational transition and should aid future searches for other rotational transitions as well.
Void configuration-induced change in microstructure and deformation mechanisms of nano-porous materials
Authors: Wang Jiapo , Liang Jianwei , Wen Zhixun , Yue Zhufeng
Published: August 2019

Void configuration plays an essential role in the deformation behavior of ductile metals; its effects on intervoid interference has not been investigated systematically until now. In the present study, molecular dynamics simulation was employed to study the void configuration-induced change in mechanical properties and deformation mechanisms during tensile loading. The results show that void configuration has a significant influence on the yield stress and yield strain, while its effect on the elastic modulus is about 3.14 ± 0.23%. The deformation mechanisms of porous materials with various void configurations at micro- and nanoscale are proposed: (i) local plastic deformation and (ii) homogeneous plastic deformation. Further analysis indicates that the difference between the above two deformation mechanisms is mainly caused by the competition and synergy between the stacking faults and dislocation. Local plastic deformation is mainly controlled by stacking faults. Homogeneous plastic deformation is dominated by dislocation motion with only a small amount of stacking shear motion, which gives material a superior plastic elongation. The result is of great value for improving the plasticity limit of nanostructures.
Non-equilibrium relaxation of hot states in organic semiconductors: Impact of mode-selective excitation on charge transfer
Authors: Alvertis Antonios M. , Schröder Florian A. Y. N. , Chin Alex W.
Published: August 2019

The theoretical study of open quantum systems strongly coupled to a vibrational environment remains computationally challenging due to the strongly non-Markovian characteristics of the dynamics. We study this problem in the case of a molecular dimer of the organic semiconductor tetracene, the exciton states of which are strongly coupled to a few hundreds of molecular vibrations. To do so, we employ a previously developed tensor network approach, based on the formalism of matrix product states. By analyzing the entanglement structure of the system wavefunction, we can expand it in a tree tensor network state, which allows us to perform a fully quantum mechanical time evolution of the exciton-vibrational system, including the effect of 156 molecular vibrations. We simulate the dynamics of hot states, i.e., states resulting from excess energy photoexcitation, by constructing various initial bath states, and show that the exciton system indeed has a memory of those initial configurations. In particular, the specific pathway of vibrational relaxation is shown to strongly affect the quantum coherence between exciton states in time scales relevant for the ultrafast dynamics of application-relevant processes such as charge transfer. The preferential excitation of low-frequency modes leads to a limited number of relaxation pathways, thus “protecting” quantum coherence and leading to a significant increase in the charge transfer yield in the dimer structure.
Perfect acoustic bandgap metabeam based on a quadruple-mode resonator array
Authors: Fujita Kentaro , Tomoda Motonobu , Wright Oliver B. , Matsuda Osamu
Published: August 2019

Solid structures guide a multitude of elastic modes of different polarizations including both compression and shear, and the nature of the elastic constant tensor implies a much richer behavior than in optics. Here, we introduce a metamaterial in the form of a rectangular cross section beam of a single isotropic material that can simultaneously suppress all elastic-wave polarizations in the beam over a range of frequencies in the kHz range. This is experimentally achieved by machining replicas of a subwavelength unit cell in an aluminum metabeam based on a planar resonator with interconnected ribs, showing complex vibrational degrees of freedom that allow it to couple to compressional, in-plane shear, flexural and torsional vibrations, that is, all four existing mode types. The result is a lightweight structure that can forbid all possible acoustic modes over the metamaterial bandgap frequency range, an exotic behavior that opens up diverse applications in easily manufacturable vibration isolation structures and acoustic wave control.
Molecular organization of mammalian meiotic chromosome axis revealed by expansion STORM microscopy
Authors: Xu Huizhong , Tong Zhisong , Ye Qing , Sun Tengqian , Hong Zhenmin , Zhang Lunfeng , Bortnick Alexandra , Cho Sunglim , Beuzer Paolo , Axelrod Joshua , Hu Qiongzheng , Wang Melissa , Evans Sylvia M. , Murre Cornelis , Lu Li-Fan , Sun Sha , Corbett Kevin D. , Cang Hu
Published: August 2019

During prophase I of meiosis, chromosomes become organized as loop arrays around the proteinaceous chromosome axis. As homologous chromosomes physically pair and recombine, the chromosome axis is integrated into the tripartite synaptonemal complex (SC) as this structure’s lateral elements (LEs). While the components of the mammalian chromosome axis/LE—including meiosis-specific cohesin complexes, the axial element proteins SYCP3 and SYCP2, and the HORMA domain proteins HORMAD1 and HORMAD2—are known, the molecular organization of these components within the axis is poorly understood. Here, using expansion microscopy coupled with 2-color stochastic optical reconstruction microscopy (STORM) imaging (ExSTORM), we address these issues in mouse spermatocytes at a resolution of 10 to 20 nm. Our data show that SYCP3 and the SYCP2 C terminus, which are known to form filaments in vitro, form a compact core around which cohesin complexes, HORMADs, and the N terminus of SYCP2 are arrayed. Overall, our study provides a detailed structural view of the meiotic chromosome axis, a key organizational and regulatory component of meiotic chromosomes.
Software for lattice light-sheet imaging of FRET biosensors, illustrated with a new Rap1 biosensor
Authors: O’Shaughnessy Ellen C. , Stone Orrin J. , LaFosse Paul K. , Azoitei Mihai L. , Tsygankov Denis , Heddleston John M. , Legant Wesley R. , Wittchen Erika S. , Burridge Keith , Elston Timothy C. , Betzig Eric , Chew Teng-Leong , Adalsteinsson David , Hahn Klaus M.
Published: August 2019

Lattice light-sheet microscopy (LLSM) is valuable for its combination of reduced photobleaching and outstanding spatiotemporal resolution in 3D. Using LLSM to image biosensors in living cells could provide unprecedented visualization of rapid, localized changes in protein conformation or posttranslational modification. However, computational manipulations required for biosensor imaging with LLSM are challenging for many software packages. The calculations require processing large amounts of data even for simple changes such as reorientation of cell renderings or testing the effects of user-selectable settings, and lattice imaging poses unique challenges in thresholding and ratio imaging. We describe here a new software package, named ImageTank, that is specifically designed for practical imaging of biosensors using LLSM. To demonstrate its capabilities, we use a new biosensor to study the rapid 3D dynamics of the small GTPase Rap1 in vesicles and cell protrusions.
Benchmarking the simplest slave-particle theory with Hubbard dimer*
Authors: Yang Wei-Wei , Luo Hong-Gang , Zhong Yin
Published: August 2019

Slave-particle method is a powerful tool to tackle the correlation effect in quantum many-body physics. Although it has been successfully used to comprehend various intriguing problems, such as Mott metal–insulator transition and Kondo effect, there is still no convincing theory so far on the availability and limitation of this method. The abuse of slave-particle method may lead to wrong physics. As the simplest slave-particle method,

Z

2

slave spin, which is widely applied to many strongly correlated problems, is highly accessible and researchable. In this work, we will uncover the nature of the

Z

2

slave-spin method by studying a two-site Hubbard model. After exploring aspects of properties of this toy model, we make a comparative analysis of the results obtained by three methods: (i) slave-spin method on mean-field level, (ii) slave-spin method with gauge constraint, and (iii) the exact solution as a benchmark. We find that, protected by the particle–hole symmetry, the slave-spin mean-field method can recover the static properties of ground state exactly at half filling. Furthermore, in the parameter space where both U and T are small enough, the slave-spin mean-field method is also reliable in calculating the dynamic and thermal dynamic properties. However, when U or T is considerably large, the mean-field approximation gives ill-defined behaviors, which result from the unphysical states in the enlarged Hilbert space. These findings lead to our conclusion that the accuracy of slave particle can be guaranteed if we can exclude all unphysical states by enforcing gauge constraints. Our work demonstrates the promising prospect of slave-particle method in studying complex strongly correlated models with specific symmetry or in certain parameter space.
Negative transconductance effect in p-GaN gate AlGaN/GaN HEMTs by traps in unintentionally doped GaN buffer layer*
Authors: Ge Mei , Cai Qing , Zhang Bao-Hua , Chen Dun-Jun , Hu Li-Qun , Xue Jun-Jun , Lu Hai , Zhang Rong , Zheng You-Dou
Published: August 2019

We investigate the negative transconductance effect in p-GaN gate AlGaN/GaN high-electron-mobility transistor (HEMT) associated with traps in the unintentionally doped GaN buffer layer. We find that a negative transconductance effect occurs with increasing the trap concentration and capture cross section when calculating transfer characteristics. The electron tunneling through AlGaN barrier and the reduced electric field discrepancy between drain side and gate side induced by traps are reasonably explained by analyzing the band diagrams, output characteristics, and the electric field strength of the channel of the devices under different trap concentrations and capture cross sections.
EPIC 202843107: a close eclipsing binary containing a δ Scuti variable
Authors: Ou Jian-Wen , Yang Ming , Zhou Ji-Lin
Published: August 2019

This paper reports on the discovery that an eclipsing binary system, EPIC 202843107, has a δ Scuti variable component. The phased light curve from the Kepler space telescope presents a detached configuration. The binary modeling indicates that the two component stars have almost the same radius and may have experienced orbital circularization. Frequency analyses are performed for the residual light curve after subtracting the binary variations. The frequency spectrum reveals that one component star is a δ Scuti variable. A large frequency separation is cross-identified with the corresponding histogram, the Fourier transform and the echelle diagram method. The mean density of the δ Scuti component is estimated to be 0.09 g cm−3 based on the large separation and density relation. Systems like EPIC 202843107 are helpful to study the stellar evolution and physical state of binary stars.
Resource potential and planning for exploration of the Hebrus Valles, Mars
Authors: Sharma Ravi , Srivastava Neeraj , Kumar Yadav Santosh
Published: August 2019

Mars is the only extraterrestrial body which could host primitive lifeforms and also has the potential to host a human base in the near future. Towards fulfilling these objectives, several remote sensing missions and rover based missions have been sent to Mars. Still, confirmation of existing or extinct life on this planet in any form has not been achieved and possibly human missions at selected sites in the future are the key to addressing this problem. Here, we have used remote sensing data from Mars Reconnaissance Orbiter (MRO; NASA), Mars Global Surveyor (MGS; NASA), Mars Odyssey (NASA) and Mars Express (MEX; ESA) to devise an exploration strategy for one such area known as Hebrus Valles, which is a potential site for human exploration of the surface of Mars. A geological context map of the Hebrus Valles and Hephaestus Fossae region has been prepared and a candidate landing site has been proposed in the Hebrus Valles region. Suitable rover paths have been worked out from the proposed landing site for harnessing the science and resource potential of the region. The proposed landing site is located in the equatorial region at (

20
°

40

′

N,

126
°

23

′

E) and due to its proximity to the Potential Subsurface Access Candidates (PSACs) in the region, such as sinkholes and skylights and also other resources such as crater ejecta, silicate material and fluvial channels, the site is appropriate for exploration of the region.
Revisiting the event rate of short GRBs and estimating their detectable number within the Advanced LIGO horizon
Authors: Liu Hao-Yang , Yu Yun-Wei
Published: August 2019

The redshift and luminosity distributions of 36 Swift short gamma-ray bursts (GRBs) are fitted by connecting their event rates with cosmic star formation rates using power-law distributed delay times

f
(
τ
)
∝

τ

−
1

, where a broken-power-law luminosity function is assumed and some empirical observational selection effects are taken into account. As a result, the most-likely model parameters are constrained to be

ν

1

=
0.91

,

ν

2

=
1.66

as power-law indices, with a break at

L

b

=
2.51
×

10

51

erg s−1 for the luminosity function and

τ

c

=
6.0

Gyr for a typical gravitational wave decay timescale of the binary orbit. The corresponding local rate of short GRBs is found to be

∼
(
3
−
4
)

Gpc

−
3

yr

−
1

. With these parameters, the detectable numbers of short GRBs are estimated within the horizon of Advanced LIGO.
Analysis of the X-ray emission of OB stars II: B stars
Authors: Ryspaeva Elizaveta , Kholtygin Alexander
Published: August 2019

This paper is the second part of an investigation into the mechanism for the origin of X-rays in early-type stars. Archival X-ray observations of 25 B stars, obtained by the XMM-Newton satellite, are analysed. We check two hypotheses on the origin of X-ray emission: the Magnetically Confined Wind Shock Model (MCWS) and Pollock’s paradigm. For all studied stars, the mean ratio of the half widths at half maximum to the terminal velocities appears to be

R
≈
0.15
−
0.20

in contradiction to Pollock’s hypothesis that

R
≈
0.5

. We checked three possible consequences of the MCWS model: correlations between the hardness of the X-ray spectra for B stars and terminal wind velocities, mass loss rates and magnetic fields. It was shown that such correlations are marginal or even absent both for magnetic and non-magnetic B stars.
Prediction of reflection coefficient of a perforated Quarter Circle Breakwater using artificial neural network (ann)
Authors: Ramesh N , Hegde ArkalVittal , Rao Subba
Published: August 2019

A breakwater is structure which is generally adopted in not only protecting the shoreline, but also in creating tranquil zone on the lee side of the structure minimizing the various movements on the anchored ships / vessels due to the wave / tidal action in the region resulting in easy handling of goods. Over the years, breakwater was generally constructed using rubble mounds. Due to the increase in demand for the coastal development all over the world, many innovative Breakwater were evolved as against the rubble mound. In the recent times, in order to economize the innovative breakwater construction, Semi Circular caisson type Breakwater has been studied. Based on Semi circularBreakwater (SBW), Quarter circular Breakwater (QBW) has been evolved. The hydrodynamic performance of a coastal structure is important, because it involves many parameters to be considered while designing a safe and economical structure. The hydro-dynamic performance of a Quarter circular breakwater is studied in a monochromatic wave flume in the Department of Applied Mechanics and Hydraulics, National Institute of Technology, Surathkal Karnataka, India. In the present paper reflection coefficient (Kr) of a perforated Quarter circular Breakwater (QBW) with various S/D ( spacing to diameter ratio) values is predicted applying Artificial Neural Network (ANN) technique using MATLAB. Four networks were constructed by varying the number of hidden layers based on the input parameters, which affects the performance of the breakwater. The predicted values of reflection coefficient using ANN, are compared with the experimental results.
Investigation of Subsonic and Hypersonic Rarefied Gas Flow over a Backward Facing Step
Authors: Nabapure Deepak , Sanwal Jayesh , Rajesh Sreeram , Ram Chandra Murthy K
Published: August 2019

In the present study the Direct Simulation Monte Carlo (DSMC) method, which is one of the widely used numerical method to study the rarefied gas flows, is applied to investigate the flow characteristics of a hypersonic and subsonic flow over a backward-facing step. The work is driven by the interest in exploring the effects of the Mach number on the rarefied flow behaviour. The primary objective of this paper is to study the variation of velocity, pressure and temperature with Mach number. The numerical tool is validated with well established results from the literature and a good agreement is found among them. The computational results indicate that the flow downstream of the step is effected by the strong expansion near the step. The compressiblity and rarefaction effects also influence the velocity and temperature distributions in the hydrodynamic and thermal boundary layers.
Numerical investigation of the flow dynamics inside single fluid and binary fluid ejectors
Authors: El Hassan Mouhammad , Bukharin Nikolay
Published: August 2019

The present study describes the flow dynamics inside a supersonic ejector using Computational Fluid Dynamics (CFD) modelling. Numerical prediction of both the mass flow rates and the wall static pressure profiles are validated using experimental measurements. Air-Air, Argon-Argon and Argon-Air cases are investigated in term of fluid mixing and ejector performance for the same boundary conditions and ejector geometry. It is found that the molar entrainment ratio is higher for Argon-Air as compared to the single fluid cases due to the higher molecular mass ratio between the primary and the secondary fluids. It is also found that the mass entrainment ratio is lower when Air is replaced with Argon as a primary fluid. New flow physics findings based on analysis of flow momentum and turbulence quantities distribution are provided in this paper to explain such behavior.
Wave transformation due to floating thick elastic plate over multiple stepped bottom topography
Authors: Praveen K M , Karmakar D
Published: August 2019

The wave transformation due to floating elastic plate is studied over multiple stepped bottom topography. The behaviour of the flexible floating plate is studied considering Timoshenko-Mindlin’s plate thick theory at finite water depth and the edge conditions for the floating plates are considered to be free-free support condition. The mathematical model is developed based on the eigenfunction expansion method to study the hydroelastic behaviour of a floating thick elastic plate at varying water depths, step thickness and plate sizes acted upon by ocean wave. The mode coupling relation is employed along with orthogonality relation and the continuity equations for velocity, pressure, deflection, bending moment, slope and shear force to determine the wave characteristics in reflection and transmission region due to variable bottom topography. The numerical computation is carried out to obtain the hydroelastic behaviour of floating elastic plate acted upon by ocean waves. Further, detail comparison of the numerical results is performed for different step bottom topography for the hydroelastic analysis of floating thick elastic plate. The present study will provide an insight into the effect of seabed profile due to the wave scattering from a large floating thick elastic plate at finite water depth.
The Effect of Transverse Injection Upstream of an Axisymmetric Aft Wall Angled Cavity in a Supersonic Flow Field
Authors: Assis Shan M , Jeyakumar S , Jayaraman K
Published: August 2019

Experiments are performed in a supersonic non-reacting flow facility to investigate the performance of an axisymmetric aft wall angled cavity with upstream fuel injection in a Mach 1.8 flow field. The supersonic combustor has a circular cross sectional duct in which cavities are introduced at a distance of 20 mm from the inlet. The aft wall of the cavity is tapered towards flow downstream and inclined with two step consecutive angles. Flush wall mounted injector is mounted at the upstream of the cavity. The tests are conducted at three fuel injection pressures to simulate the flow field in the present study. The mixing performance of the aft wall angled cavities are analysed based on the momentum flux distribution at the exit of the combustor and the stagnation pressure loss across the combustor and compared with the rectangular cavity. Transverse upstream injection of aft wall angled cavities enhances mixing than rectangular cavities, deliberated with less stagnation pressure loss from the former. Increase in injection pressures resulted in more uniform mixing across the flow direction of the combustor irrespective of the cavity configuration, concurrently induces more stagnation pressure loss due to increase in jet penetration depth into the main stream.
A noble method for rapid prototyping of porous micromodels applicable to enhanced oil recovery
Authors: Haque N , Singh A , Saha U K
Published: August 2019

In this paper, a noble method for rapid prototyping of porous micromodel in Polydimethylsiloxane (PDMS) with good control over the pore geometry is described. An attempt has been made to demonstrate the making of PDMS micromodels using round hole perforated metal sheet as a master. The geometric shape of the micromodel in PDMS is the negative of the perforated sheet, which gives a section of cylindrical pillars separated by a uniform gap. After peeling off the PDMS from the porous plate, it is sealed with a glass plate to prepare the microfluidic porous channel. This protocol requires only materials that are commercially available, inexpensive and less time consuming. The size of the pores can be adjusted by selecting the perforated sheets having different hole size and thus micromodels with a variety of pore size distribution can be generated using this simple method. The optical visualization experiments were performed to test these fabricated micromodels for their applicability and reliability. Furthermore, Particle Image Velocimetry (PIV) technique is used to get the velocity distribution along the porous section of the micromodel. Identical flow patterns were seen at the different section of the micromodel which again indicated the reliablility of these homogeneous micromodel fabricated by using this noble method. In addition, the velocity profiles are obtained near the throat region of the micromodel at three different flow rates.
Modeling of liquid-solid flow erosion in curved pipes of gradually varying cross section
Authors: Xijie Liu , Ainane Sami , Yit Fatt Yap
Published: August 2019

Liquid-solid flow erosion in curved pipes of gradually varying cross section is investigated. The model consists of three components integrated: Fluid Transport to describe the flowing fluid via Reynolds-Averaged Navier-Stokes equations with standard k-ε turbulence model, Particle Transport to describe the trajectories of the solid particles using Discrete Particle Modeling (DPM) and Particle Erosion to describe the erosion rate using Oka erosion model. The model is validated against experimental data for erosion in curved pipe of constant cross section. This study focuses at the geometrical effect of curved pipes, i.e. converging, constant cross section and diverging, on erosion. Both maximum erosion and locations where it occurs are identified. Results show that curved converging pipes suffer from high erosion rate concentrated especially in the outer wall of the curved section. Curved diverging pipes on the other hand has much lower erosion of erosion rate at least one order of magnitude lower compared against that of diverging pipes and concentrated on the side wall of the curved section. This very different erosion behavior is highlighted in the study.