bluuebunny/crossref_metadata_2025 huggingface dataset:
A novel hybrid method for the calculation of methane hydrate–water interfacial tension along the three-phase (hydrate–liquid water–vapor) equilibrium line
Authors: Tsimpanogiannis Ioannis N.
Published: July 2021

We use a novel hybrid method to explore the temperature dependence of the solid–liquid interfacial tension of a system that consists of solid methane hydrate and liquid water. The calculated values along the three-phase (hydrate–liquid water–vapor) equilibrium line are obtained through the combination of available experimental measurements and computational results that are based on approaches at the atomistic scale, including molecular dynamics and Monte Carlo. An extensive comparison with available experimental and computational studies is performed, and a critical assessment and re-evaluation of previously reported data is presented.
Systematic comparison between the generalized Lorenz equations and DNS in the two-dimensional Rayleigh–Bénard convection
Authors: Park Junho , Moon Sungju , Seo Jaemyeong Mango , Baik Jong-Jin
Published: July 2021

The classic Lorenz equations were originally derived from the two-dimensional Rayleigh–Bénard convection system considering an idealized case with the lowest order of harmonics. Although the low-order Lorenz equations have traditionally served as a minimal model for chaotic and intermittent atmospheric motions, even the dynamics of the two-dimensional Rayleigh–Bénard convection system is not fully represented by the Lorenz equations, and such differences have yet to be clearly identified in a systematic manner. In this paper, the convection problem is revisited through an investigation of various dynamical behaviors exhibited by a two-dimensional direct numerical simulation (DNS) and the generalized expansion of the Lorenz equations (GELE) derived by considering additional higher-order harmonics in the spectral expansions of periodic solutions. Notably, GELE allows us to understand how nonlinear interactions among high-order modes alter the dynamical features of the Lorenz equations including fixed points, chaotic attractors, and periodic solutions. It is verified that numerical solutions of the DNS can be recovered from the solutions of GELE when we consider the system with sufficiently high-order harmonics. At the lowest order, the classic Lorenz equations are recovered from GELE. Unlike in the Lorenz equations, we observe limit tori, which are the multi-dimensional analog of limit cycles, in the solutions of the DNS and GELE at high orders. Initial condition dependency in the DNS and Lorenz equations is also discussed.
Unexpected thermo-elastic effects in liquid glycerol by mechanical deformation
Authors: Kume Eni , Zaccone Alessio , Noirez Laurence
Published: July 2021

It is commonly accepted that shear waves do not propagate in a liquid medium. The shear wave energy is supposed to dissipate nearly instantaneously. This statement originates from the difficulty to access “static” shear stress in macroscopic liquids. In this paper, we take a different approach. We focus on the stability of the thermal equilibrium while the liquid (glycerol) is submitted to a sudden shear strain at sub-millimeter scale. The thermal response of the deformed liquid is unveiled. The liquid exhibits simultaneous and opposite bands up to about +0.04 to −0.04 °C temperature variation, while keeping the global thermal balance unchanged. The sudden thermal changes and the long thermal relaxation highlight the ability of the liquid to convert the step strain energy in non-uniform thermodynamic states. The thermal effects depend nearly linearly on the amplitude of the deformation supporting the hypothesis of a shear wave propagation (elastic correlations) extending up to several hundreds micrometers. This new physical effect can be explained in terms of the underlying phonon physics of confined liquids, which unveils a hidden solid-like response with many similarities to glassy systems.
Competing interactions in the depletion forces of ternary colloidal mixtures
Authors: de los Santos-López Néstor M. , Pérez-Ángel Gabriel , Méndez-Alcaraz José M. , Castañeda-Priego Ramón
Published: July 2021

Depletion interactions between colloidal particles surrounded by smaller depletants are typically characterized by a strong attraction at contact and a moderately repulsive barrier in front of it that extends at distances similar to the size of the depletants; the appearance and height of the barrier basically depend on the concentration and, therefore, the correlation between depletants. From a thermodynamic point of view, the former can drive the system to phase separation or toward non-equilibrium states, such as gel-like states, but its effects on both local and global properties may be controlled by the latter, which acts as a kind of entropic gate. However, the latter has not been entirely analyzed and understood within the context of colloidal mixtures mainly driven by entropy. In this contribution, we present a systematic study of depletion forces in ternary mixtures of hard spherical particles with two species of depletants, in two and three dimensions. We focus the discussion on how the composition of the depletants becomes the main physical parameter that drives the competition between the attractive well and the repulsive barrier. Our results are obtained by means of the integral equation theory of depletion forces and techniques of contraction of the description adapted to molecular dynamics computer simulations.
Using silicon-vacancy centers in diamond to probe the full strain tensor
Authors: Bates Kelsey M. , Day Matthew W. , Smallwood Christopher L. , Owen Rachel C. , Schröder Tim , Bielejec Edward , Ulbricht Ronald , Cundiff Steven T.
Published: July 2021

An ensemble of silicon vacancy (SiV−) centers in diamond is probed using two-pulse correlation spectroscopy and multidimensional coherent spectroscopy. Two main distinct families of SiV− centers are identified, and these families are paired with two orientation groups by comparing spectra from different linear polarizations of the incident laser. By tracking the peak centers in the measured spectra, the full diamond strain tensor is calculated local to the laser spot. Measurements are made at multiple points on the sample surface, and variations in the strain tensor are observed.
Powder conductor for pressure calibration applied to large volume press under high pressure
Authors: Huang Mengyang , Peng Fang , Guan Shixue , Zhang Jiawei , Liang Wenjia , Wang Junpu , Tian Yi , Su Yuzhu , Tang Yue , Wang Wenqiang , He Duanwei
Published: July 2021

Pressure is the core of high-pressure science and technology, and the accuracy of pressure calibration is of much importance for high-pressure experiments and production. Although the pressure limit of the large volume press (LVP) continues to increase, there are no well solutions for in situ pressure calibration. In this study, using in situ high-pressure electrical performance measurement technology, two ideal calibration standard materials in powder conductors, cadmium phosphide (Cd3P2) and zinc telluride (ZnTe) with stable physical and chemical properties and obvious resistance change, are applied to pressure calibration in the LVP. In situ high-pressure synchrotron radiation x-ray diffraction was used to verify the phase transition pressure point of Cd3P2. The introduction of powder conductors for pressure calibration commits to establish a pressure system, which is safer, more stable to operate, and more accurate in experimental measurements for the LVP.
Optimal test-kit-based intervention strategy of epidemic spreading in heterogeneous complex networks
Authors: Ghosh Subrata , Senapati Abhishek , Chattopadhyay Joydev , Hens Chittaranjan , Ghosh Dibakar
Published: July 2021

We propose a deterministic compartmental model of infectious disease that considers the test kits as an important ingredient for the suppression and mitigation of epidemics. A rigorous simulation (with an analytical argument) is provided to reveal the effective reduction of the final outbreak size and the peak of infection as a function of basic reproduction number in a single patch. Furthermore, to study the impact of long and short-distance human migration among the patches, we consider heterogeneous networks where the linear diffusive connectivity is determined by the network link structure. We numerically confirm that implementation of test kits in a fraction of nodes (patches) having larger degrees or betweenness centralities can reduce the peak of infection (as well as the final outbreak size) significantly. A next-generation matrix-based analytical treatment is provided to find out the critical transmission probability in the entire network for the onset of epidemics. Finally, the optimal intervention strategy is validated in two real networks: the global airport network and the transportation network of Kolkata, India.
The phase diagram of carbon dioxide from correlation functions and a many-body potential
Authors: Chen Amanda A. , Do Alexandria , Pascal Tod A.
Published: July 2021

The phase stability and equilibria of carbon dioxide are investigated from 125–325 K and 1–10 000 atm using extensive molecular dynamics (MD) simulations and the Two-Phase Thermodynamics (2PT) method. We devise a direct approach for calculating phase diagrams, in general, by considering the separate chemical potentials of the isolated phase at specific points on the P–T diagram. The unique ability of 2PT to accurately and efficiently approximate the entropy and Gibbs energy of liquids allows for assignment of phase boundaries from relatively short (∼100 ps) MD simulations. We validate our approach by calculating the critical properties of the flexible elementary physical model 2, showing good agreement with previous results. We show, however, that the incorrect description of the short-range Pauli force and the lack of molecular charge polarization lead to deviations from experiments at high pressures. We, thus, develop a many-body, fluctuating charge model for CO2, termed CO2–Fq, from high level quantum mechanics (QM) calculations that accurately capture the condensed phase vibrational properties of the solid (including the Fermi resonance at 1378 cm−1) as well as the diffusional properties of the liquid, leading to overall excellent agreement with experiments over the entire phase diagram. This work provides an efficient computational approach for determining phase diagrams of arbitrary systems and underscores the critical role of QM charge reorganization physics in molecular phase stability.
Understanding carbon dioxide capture on metal–organic frameworks from first-principles theory: The case of MIL-53(X), with X = Fe3+, Al3+, and Cu2+
Authors: Damas Giane B. , Costa Luciano T. , Ahuja Rajeev , Araujo C. Moyses
Published: July 2021

Metal–organic frameworks (MOFs) constitute a class of three-dimensional porous materials that have shown applicability for carbon dioxide capture at low pressures, which is particularly advantageous in dealing with the well-known environmental problem related to the carbon dioxide emissions into the atmosphere. In this work, the effect of changing the metallic center in the inorganic counterpart of MIL-53 (X), where X = Fe3+, Al3+, and Cu2+, has been assessed over the ability of the porous material to adsorb carbon dioxide by means of first-principles theory. In general, the non-spin polarized computational method has led to adsorption energies in fair agreement with the experimental outcomes, where the carbon dioxide stabilizes at the pore center through long-range interactions via oxygen atoms with the axial hydroxyl groups in the inorganic counterpart. However, spin-polarization effects in connection with the Hubbard corrections, on Fe 3d and Cu 3d states, were needed to properly describe the metal orbital occupancy in the open-shell systems (Fe- and Cu-based MOFs). This methodology gave rise to a coherent high-spin configuration, with five unpaired electrons, for Fe atoms leading to a better agreement with the experimental results. Within the GGA+U level of theory, the binding energy for the Cu-based MOF is found to be Eb = −35.85 kJ/mol, which is within the desirable values for gas capture applications. Moreover, it has been verified that the adsorption energetics is dominated by the gas–framework and internal weak interactions.
Field-theoretic simulations beyond δ-interactions: Overcoming the inverse potential problem in auxiliary field models
Authors: Weyman Alexander , Mavrantzas Vlasis G. , Öttinger Hans Christian
Published: July 2021

Modern field-theoretic simulations of complex fluids and polymers are constructed around a particle-to-field transformation that brings an inverse potential u−1 in the model equations. This has restricted the application of the framework to systems characterized by relatively simple pairwise interatomic interactions; for example, excluded volume effects are treated through the use of δ-function interactions. In this study, we first review available nonbonded pair interactions in field-theoretic models and propose a classification. Then, we outline the inverse potential problem and present an alternative approach on the basis of a saddle-point approximation, enabling the use of a richer set of pair interaction functions. We test our approach by using as an example the Morse potential, which finds extensive applications in particle-based simulations, and we calibrate u−1 with results from a molecular dynamics simulation. The u−1 thus obtained is consistent with the field-theoretic model equations, and when used in stand-alone self-consistent field simulations, it produces the correct fluid structure starting from a random initial state of the density field.
A study of the internal vibration of a single oscillating bubble
Authors: Yu Y. Q. , Zong Z.
Published: July 2021

A model for the compressible gas inside a single oscillating bubble is developed and found to have a wave-like distribution. Both gas sphere and ambient incompressible liquid are simplified as inviscid, ideal fluids. The density and pressure in the gas sphere are described by the Euler equations with analytical solutions obtained using the perturbation method. The zero-order quantities follow a uniform distribution. By introducing co-moving coordinates, the first-order quantities, which indicate the wave-like gas distribution, are obtained. The effect of the bubble oscillation on acoustic gas perturbations is included in our theory, and it results in a new wave equation, which describes internal wave-like distribution. According to our theory, the gas vibration induces local pressure peaks in the ambient liquid. Our theoretical description of the pressure peaks agrees with experimental observations. The observability of the internal oscillation is also discussed.
Impact of quantum-chemical metrics on the machine learning prediction of electron density
Authors: Briling Ksenia R. , Fabrizio Alberto , Corminboeuf Clemence
Published: July 2021

Machine learning (ML) algorithms have undergone an explosive development impacting every aspect of computational chemistry. To obtain reliable predictions, one needs to maintain a proper balance between the black-box nature of ML frameworks and the physics of the target properties. One of the most appealing quantum-chemical properties for regression models is the electron density, and some of us recently proposed a transferable and scalable model based on the decomposition of the density onto an atom-centered basis set. The decomposition, as well as the training of the model, is at its core a minimization of some loss function, which can be arbitrarily chosen and may lead to results of different quality. Well-studied in the context of density fitting (DF), the impact of the metric on the performance of ML models has not been analyzed yet. In this work, we compare predictions obtained using the overlap and the Coulomb-repulsion metrics for both decomposition and training. As expected, the Coulomb metric used as both the DF and ML loss functions leads to the best results for the electrostatic potential and dipole moments. The origin of this difference lies in the fact that the model is not constrained to predict densities that integrate to the exact number of electrons N. Since an a posteriori correction for the number of electrons decreases the errors, we proposed a modification of the model, where N is included directly into the kernel function, which allowed lowering of the errors on the test and out-of-sample sets.
Symmetry kills the square in a multifunctional reservoir computer
Authors: Flynn Andrew , Herteux Joschka , Tsachouridis Vassilios A. , Räth Christoph , Amann Andreas
Published: July 2021

The learning capabilities of a reservoir computer (RC) can be stifled due to symmetry in its design. Including quadratic terms in the training of a RC produces a “square readout matrix” that breaks the symmetry to quell the influence of “mirror-attractors,” which are inverted copies of the RC’s solutions in state space. In this paper, we prove analytically that certain symmetries in the training data forbid the square readout matrix to exist. These analytical results are explored numerically from the perspective of “multifunctionality,” by training the RC to specifically reconstruct a coexistence of the Lorenz attractor and its mirror-attractor. We demonstrate that the square readout matrix emerges when the position of one attractor is slightly altered, even if there are overlapping regions between the attractors or if there is a second pair of attractors. We also find that at large spectral radius values of the RC’s internal connections, the square readout matrix reappears prior to the RC crossing the edge of chaos.
Agonist of growth hormone–releasing hormone enhances retinal ganglion cell protection induced by macrophages after optic nerve injury
Authors: Cen Ling-Ping , Ng Tsz Kin , Liang Jia-Jian , Xu Ciyan , Zhuang Xi , Liu Yu-Fen , Chen Shao-Lang , Xu Yanxuan , Yang Qichen , Yuan Xiang-Ling , Qin Yong Jie , Chan Sun On , Chen Haoyu , Zhang Mingzhi , Schally Andrew V. , Pang Chi Pui
Published: July 2021

Significance

Optic neuropathies, characterized by the degeneration of retinal ganglion cells (RGCs) and their axons, are leading causes of irreversible blindness and visual impairment, for which currently there is no effective treatment or cure. This study demonstrates that subcutaneous application of an agonist or antagonist of growth hormone–releasing hormone (GHRH) reduces the degeneration of RGCs induced by optic nerve injury in rats. GHRH agonist further enhances the neuroprotective effect of macrophage activation on the survival of RGCs. Our findings demonstrate the therapeutic potential of GHRH agonist for the protection of RGCs against optic neuropathies, including glaucoma, the world’s most common cause of irreversible blindness.
HIPK2 phosphorylates HDAC3 for NF-κB acetylation to ameliorate colitis-associated colorectal carcinoma and sepsis
Authors: Zhang Fang , Qi Linlin , Feng Qiuyun , Zhang Baokai , Li Xiangyue , Liu Chang , Li Weiyun , Liu Qiaojie , Yang Dan , Yin Yue , Peng Chao , Wu Han , Tang Zhao-Hui , Zhou Xi , Xiang Zou , Zhang Zhijiang , Wang Hongyan , Wei Bin
Published: July 2021

Significance

Multiple human diseases including cancer and sepsis are closely related to uncontrolled inflammation. However, there is not much success for clinical therapy to date by targeting specific inflammatory cytokines. Since NF-κB–mediated transactivation in the nucleus is pivotal downstream of various stimuli to induce inflammation, searching the nuclear-localized targets specifically regulating NF-κB activation will provide important therapeutic application. This study has found that HIPK2 restrains NF-κB activation through phosphorylating HDAC3 at serine 374 to inactive HDAC3 deacetylase activity, thus reducing the p65 deacetylation and suppressing inflammation. Our findings reveal a function of the HIPK2-HDAC3-p65 module in macrophages to restrain excessive inflammation, which may represent a therapeutic mechanism for inflammation-related diseases.
Quantification and demonstration of the collective constriction-by-ratchet mechanism in the dynamin molecular motor
Authors: Ganichkin Oleg M. , Vancraenenbroeck Renee , Rosenblum Gabriel , Hofmann Hagen , Mikhailov Alexander S. , Daumke Oliver , Noel Jeffrey K.
Published: July 2021

Significance

Dynamin is a protein that is a central player in endocytosis, a process that mediates the entry of diverse particles into cells, from nutrients to viruses. Dynamin’s primary activity is to use guanosine triphosphate as fuel to constrict and cut membrane tubes. Key quantitative aspects of its function remain yet unclear. In this work, we determine the strength of an individual dynamin motor. Then, by building a detailed computational model resolving individual motors, we demonstrate that dynamin produces sufficient force to tightly constrict a membrane tube when most of its motors are simultaneously cooperating. Hence, we quantitatively validate the prevailing constriction-by-ratchet model for nature’s strongest torque-generating motor: the dynamin “nanomuscle.”
PIEZO2 mediates ultrasonic hearing via cochlear outer hair cells in mice
Authors: Li Jie , Liu Shuang , Song Chenmeng , Hu Qun , Zhao Zhikai , Deng Tuantuan , Wang Yi , Zhu Tong , Zou Linzhi , Wang Shufeng , Chen Jiaofeng , Liu Lian , Hou Hanqing , Yuan Kexin , Zheng Hairong , Liu Zhiyong , Chen Xiaowei , Sun Wenzhi , Xiao Bailong , Xiong Wei
Published: July 2021

Significance

Some animals have evolved an adaptive ability for vocalizing and hearing ultrasonic frequencies that are inaudible to humans (>20 kHz). For decades, it has been postulated that animals hear ultrasonic frequencies with cochlear hair cells using an identical set of mechanotransduction molecules in the hair bundles for hearing audible frequencies. Here, we show that mice lacking mechanosensitive PIEZO2 ion channels have difficulty hearing at ultrasonic frequencies but remain remarkably sensitive to audible frequencies. Thus, animals may use a partially different mechanism for sensing ultrasonic sound emissions.
From linear to metric functional analysis
Authors: Karlsson Anders
Published: July 2021

Significance

Metric geometry is a considerable extension of Riemannian geometry that, in recent decades, has proven very useful. A newer direction described in this article can moreover be viewed as an extension of functional analysis. I try to illustrate why these more recent concepts and results will be of importance, potentially generating new ideas in applied mathematics, for example, deep learning or evolution dynamics. An important objective of this note is therefore also to try to attract the attention of scientists in other disciplines. An extension of the contraction mapping principle and a recent fundamental theorem on the behavior of the composition of randomly selected transformation have vast potential for further applications.
MAGUKs are essential, but redundant, in long-term potentiation
Authors: Chen Xiumin , Fukata Yuko , Fukata Masaki , Nicoll Roger A.
Published: July 2021

Significance

It is now generally accepted that memories are stored, at least in part, by long-term potentiation (LTP), in which brief activation of excitatory synapses persistently enhances synaptic transmission. LTP involves the recruitment of AMPARs to the synapse, but the mechanism remains debated. This study shows that the MAGUK family of scaffolding proteins plays an essential, but redundant, role in LTP. MAGUK binding to the transsynaptic adhesion protein ADAM22 is proposed to localize AMPARs immediately across from the vesicle release site. Such a mechanism ensures reliable AMPAR activation following glutamate release.
A ciliopathy complex builds distal appendages to initiate ciliogenesis
Authors: Kumar Dhivya , Rains Addison , Herranz-Pérez Vicente , Lu Quanlong , Shi Xiaoyu , Swaney Danielle L. , Stevenson Erica , Krogan Nevan J. , Huang Bo , Westlake Christopher , Garcia-Verdugo Jose Manuel , Yoder Bradley K. , Reiter Jeremy F.
Published: July 2021

Cells inherit two centrioles, the older of which is uniquely capable of generating a cilium. Using proteomics and superresolved imaging, we identify a module that we term DISCO (distal centriole complex). The DISCO components CEP90, MNR, and OFD1 underlie human ciliopathies. This complex localizes to both distal centrioles and centriolar satellites, proteinaceous granules surrounding centrioles. Cells and mice lacking CEP90 or MNR do not generate cilia, fail to assemble distal appendages, and do not transduce Hedgehog signals. Disrupting the satellite pools does not affect distal appendage assembly, indicating that it is the centriolar populations of MNR and CEP90 that are critical for ciliogenesis. CEP90 recruits the most proximal known distal appendage component, CEP83, to root distal appendage formation, an early step in ciliogenesis. In addition, MNR, but not CEP90, restricts centriolar length by recruiting OFD1. We conclude that DISCO acts at the distal centriole to support ciliogenesis by restraining centriole length and assembling distal appendages, defects in which cause human ciliopathies.
zapERtrap: A light-regulated ER release system reveals unexpected neuronal trafficking pathways
Authors: Bourke Ashley M. , Schwartz Samantha L. , Bowen Aaron B. , Kleinjan Mason S. , Winborn Christina S. , Kareemo Dean J. , Gutnick Amos , Schwarz Thomas L. , Kennedy Matthew J.
Published: July 2021

Here we introduce zapalog-mediated endoplasmic reticulum trap (zapERtrap), which allows one to use light to precisely trigger forward trafficking of diverse integral membrane proteins from internal secretory organelles to the cell surface with single cell and subcellular spatial resolution. To demonstrate its utility, we use zapERtrap in neurons to dissect where synaptic proteins emerge at the cell surface when processed through central (cell body) or remote (dendrites) secretory pathways. We reveal rapid and direct long-range trafficking of centrally processed proteins deep into the dendritic arbor to synaptic sites. Select proteins were also trafficked to the plasma membrane of the axon initial segment, revealing a novel surface trafficking hotspot. Proteins locally processed through dendritic secretory networks were widely dispersed before surface insertion, challenging assumptions for precise trafficking at remote sites. These experiments provide new insights into compartmentalized secretory trafficking and showcase the tunability and spatiotemporal control of zapERtrap, which will have broad applications for regulating cell signaling and function.
Inversion of α-sine and α-cosine transforms on

R
Authors: Hoang Ly Viet , Spodarev Evgeny
Published: July 2021

We consider the α-sine transform of the form

T

α

f

(

y

)

=

∫

0

∞

|
sin

(

x
y

)

|

α

f

(

x

)

d
x

for α > −1, where f is an integrable function on

R

+

. First, the inversion of this transform for α > 1 is discussed in the context of a more general family of integral transforms on the space of weighted, square-integrable functions on the positive real line. In an alternative approach, we show that the α-sine transform of a function f admits a series representation for all α > −1, which involves the Fourier transform of f and coefficients which can all be explicitly computed with the Gauss hypergeometric theorem. Based on this series representation we construct a system of linear equations whose solution is an approximation of the Fourier transform of f at equidistant points. Sampling theory and Fourier inversion allow us to compute an estimate of f from its α-sine transform. The same approach can be extended to a similar α-cosine transform on

R

+

for α > −1, and the two-dimensional spherical α-sine and cosine transforms for α > −1, α ≠ 0, 2, 4, …. In an extensive numerical analysis, we consider a number of examples, and compare the inversion results of both methods presented.
A unified scheme for rotation modulation and self-calibration of dual-axis rotating SINS
Authors: Fan Huiying , Xie Yuanping , Wang Zichao , Wang Lin , Luo Hui , Yu Xudong
Published: July 2021

Rotation modulation and self-calibration are the key techniques for error compensation of the strapdown inertial navigation system, which are generally implemented separately. The 16-sequence scheme is widely used for rotation modulation, while the 18-sequence scheme is used for self-calibration. To reduce the complexity of the practical operations, this paper proposes the combination of the rotation modulation scheme and the calibration path and six corresponding design principles of the scheme with both rotation modulation and self-calibration functions. A 48-sequence rotation scheme is designed, which unifies the scheme for self-calibration and rotation modulation. The simulation and experiment results prove that, compared with the 16-sequence rotation modulation scheme, the proposed 48-sequence scheme can reduce the mathematical platform misalignment angle errors and the sawtooth type velocity errors caused by the misalignments of the inertial measurement unit. Besides, its accuracy of self-calibration is better than that of the 18-sequence self-calibration scheme. The velocity errors and position errors can be reduced by about 0.1 m s−1 and 0.2 nm in 3 d.
Viscoelastic constitutive models and their fractional representatives to capture the time-dependent response of DEAs on sinus excitation
Authors: Karner Timi , Gotlih Janez
Published: July 2021

Dielectric elastomer actuators (DEAs) are subjected to creep especially in the first few excitation cycles. This paper deals with viscoelastic constitutive models and their fractional representatives to capture time-dependent deformation of DEA on sinus excitation. The sine voltage signal with three different frequencies and the same amplitude was used for deformation of the DEA. Basic constitutive models and their fractional representations of Kelvin–Voigt, Zener, solid linear model (SLM), Burger model and Kelvin–Voigt–Maxwell model were taken into consideration for finding the optimal model describing the behavior of the DEA. The simplicity of forming governing equations of motion derived with the help of Laplace transformation for basic and fractional constitutive models is shown in the work. Electrical force was calculated with the help of Maxwell equation. Responses of constitutive models were calculated with the help of Matlab. Constitutive parameters were optimized with the help of direct search and multiple starting point search method in Matlab. Fractional SLM was found to be the most optimal for describing time-dependent deformation on sinus excitation signal for the DEA. This work can be the basis on which control algorithms can be simulated for control of the DEA or any similar soft actuator.
Radiation reaction of betatron oscillation in plasma wakefield accelerators
Authors: Zeng Ming , Seto Keita
Published: July 2021

A classical model of radiation reaction for the betatron oscillation of an electron in a plasma wakefield accelerator is presented. The maximum energy of the electron due to the longitudinal radiation reaction is found, and the betatron oscillation damping due to both the longitudinal and transverse radiation reaction effects is analyzed. Both theoretical and numerical solutions are shown with good agreements. The regime that the quantum radiation takes effect is also discussed. This model is important for designing future plasma based super accelerators or colliders.
Synthesis of Silver-Alginate Nanocomposites Colloidal Assisted by Microwave Irradiation as Antibacterial Material
Authors: Susilowati E , Masykuri M , Ulfa M , Hardini R D
Published: July 2021

Synthesis of silver-alginate nanocomposite colloidal as an antibacterial material has been done. The colloidal is prepared through a chemical reduction method assisted by microwave irradiation with alginat as a reducing agent and stabilizer. Silver nitrate is used as a precursor and NaOH as an accelerator. The formation of silver-nanoparticles was indicated using a UV-Vis spectrophotometer based on localized surface plasmon resonance (LSPR) phenomenon. The shape and size of silver nanoparticles were characterized using TEM. Effect of storage in ambient temperature of silver-alginate nanocomposites colloidal was carried out during 14 weeks. Investigation of antibacterial activity of silver-alginate nanocomposite was carried out using diffusion method. The results showed that, the concentration of NaOH, irradiation time, AgNO3 concentration affect to the absorption band of the LSPR which related with the number of nanoparticles produced. Based on the TEM images, the size of silver nanoparticles increased with increasing concentration of AgNO3. Silver-alginate nanocomposites was stable for 12 weeks based on the absorption band of the LSPR. The greater the concentration of silver nanoparticles in silver-alginate nanocomposites, tends to the higher their antibacterial properties.
Applications of Laplace Transform in science and technology
Authors: Kokane Ashok S , Wadkar Balaji R
Published: July 2021

In the present paper, we discussed applications of Laplace Transform to solve the equations that occur in mathematical modeling of various engineering problems like simple electric circuit, in analysis and modeling of Mechanical system, in population growth, in conduction of heat equation (with example), in Bessel’s function and in economics. We interpreted a relation between beta and gamma function and applications to simultaneous differential equations with suitable example using Laplace Transform Method.
Simulation and discussion of CO2 flooding associated gas separation by mixed amine absorption method
Authors: Chen Bing , Zhao Qiong , Cui Weigang
Published: July 2021

Separating the CO2 from the associated gas is the key to improving resource utilization and reducing environmental pollution. It is confirmed that the MDEA-MEA mixture is used as the absorption liquid according to the composition and pressure of the associated gas in the current oil field. Taking a domestic CO2 flooding produced liquid as the research object. The separation process was simulated by Aspen HYSYS software, and compared with the actual absorption and separation situation. According to simulation calculation, for the associated gas with a CO2 proportion of 30%, the separation rate of CO2 by the system can reach 98.32%, and the purity of CO2 is 99.28%. Furthermore, it provides a technical example for rational use of simulation calculation to estimate the efficiency of CO2 separation by mixed amine absorption method in engineering.
Study on determination method of substitution degree of polyvinyl alcohol glutaraldehyde
Authors: Wang Wenbin , Zhang Jian , Min Jiangben , Du Weichao
Published: July 2021

The excess hydroxylamine hydrochloride was added to react with PVA crosslink, and the HCI was titrated with NaOH standard solution. The weight percentage of PVA crosslink in the sample was calculated to characterize the degree of substitution. The results show that this method can be used to analyze the degree of substitution of PVA and glutaraldehyde crosslinking reaction effectively with high accuracy and small standard deviation.
Relationship Between Organic Geochemistry and Hydrocarbon Preservation in Longmen Mountain Structural Belts
Authors: Liang Min , Wang Hui , Fan Yuhai
Published: July 2021

Based on the analysis data of biomarkers and group components of crude oil and asphalt, this paper analyzes the organic geochemical characteristics of hydrocarbon in this area and its relationship with hydrocarbon preservation, understands the preservation and damage of hydrocarbon reservoirs, and then evaluates the resource exploration prospects of main hydrocarbon-bearing structures. Comprehensive study shows that the Longmen Mountain thrust nappe belt experienced the influence of multistage tectonic movement, resulting in the destruction of hydrocarbon-bearing structures in different degrees in space. The northern part of the Longmen Mountain structural belts underwent strong deformation during Indosinian and Himalayan periods, and the organic geochemical indicators showed that the hydrocarbon-bearing structures preservation conditions in the area were poor; the southern part of the Longmen Mountain structural belts and the Western Sichuan depression had moderate internal structural deformation, the Jurassic and Cretaceous systems were well preserved, with large stratigraphic thickness and good hydrocarbon preservation conditions.
Research and field application of ultra high pressure hydraulic cutting technology in Gaohe coal minethe title of your paper here
Authors: Ji Fei , Lu Zhanjin
Published: July 2021

In order to improve the permeability of low permeability coal seam, improve the gas drainage efficiency of + 450m bedding boreholes in Gaohe mine, and ensure the safe and rapid excavation of + 450m level north wing air inlet roadway, ZGF-100 (a) type ultra-high pressure hydraulic slotting device suitable for the characteristics of 3 coal seam in Gaohe mine is developed. The feasibility and implementation scheme of high pressure water drilling and slotting integration technology are studied, and the slotting effect is preliminarily analyzed investigate. The research shows that the technology of using ultra-high pressure water to cut coal seam to cause cracks and increase permeability can effectively conduct the original cracks in the coal body, increase the gas drainage effect of boreholes along the seam, increase the drainage pure quantity by 1.8 ∼ 3.6 times, increase the effective drainage radius from 1.3m to 2.4m, and reduce the drilling engineering quantity by more than 50%. Hydraulic cutting technology can effectively improve the gas drainage efficiency of low permeability coal seam, which is worthy of promotion.
Identification of igneous reservoir fluid properties based on apparent formation water resistivity P1/2 method -- Taking Carboniferous igneous rocks in CH302, Junggar Basin as an example
Authors: Jin Ping , Hu Gang , Wang Xian , Cheng Zhongjiang , Zhang Shangming
Published: July 2021

In this paper, the application of apparent formation water resistivity P1/2 method to the identification of igneous reservoir fluid properties is explored. This method is applied to basalt and volcanic breccia in CH302 well area of Junggar basin, which has certain application value, but has certain limitations. When the apparent formation resistivity P1/2 method is applied to the fluid property identification of igneous reservoir, the identification effect will be affected by the accuracy of lithology classification, igneous fracture and oil bearing property.
Application of information technology in geological exploration
Authors: Wang Juan , Chen Fang , Yao Weihua , Huang Ligang , Wu Fan
Published: July 2021

With the development of modern exploration technology, the role of geological exploration is becoming more and more important, it is used in many fields. The development of information technology has gone deep into all fields of production and life, and its application in geological exploration has brought considerable development to oil and gas exploration and energy industry. The traditional oil and gas exploration and production technology is difficult to meet the huge demand for energy, and the application of information technology is a good solution to this problem. This paper studies current situation of information technology in geological exploration, the restrictive factors of the application of information technology in geological exploration and the restrictive factors of the application of information technology in geological exploration, and summarizes the relevant conclusions.
Investigation on microstructure and fracture behaviour of titanium alloy castings
Authors: Zhao Wenxia , Tao Chunhu , Liu Changkui
Published: July 2021

OM, SEM, EDS, XRD were used to investigate microstructure and element distribution of titanium alloy castings, mechanical properties was examined by tensile test and micro-hardness. Results of the study showed that the micro-hardness of the abnormal microstructure was higher than that of the normal, the brittle fracture behaviour was showed in abnormal microstructure and the plastic fracture behaviour was showed in normal. The content of Fe was detected at abnormal microstructure, which lead to the content of β phase of abnormal area far exceeded the normal area, and β flecks appeared. The segregation of Fe element is the root cause which led to forming abnormal structure and β flecks, as well as the sharp plasticity decreases of alloy. The segregation of Fe changes the structure of the alloy, which leads to the formation of brittle TiFe eutectic phase causing the increases the strength but reduces the alloy casting plasticity.
Visualization Research and Application of Uncertainty Method of Well Trajectory Based on ISCWSA Model
Authors: Ma Hongyan , Xu Xiaoou , Xu Hongguo , Song Xiaojian , Zhang Aibing , Wang Xuelong , Wang Yarong , Liu Wenmao , Dong Jinghui , Guo Yufeng
Published: July 2021

In order to improve the control accuracy of well trajectory and the visualization technology of drilling data, the measurement error source is analyzed based on MWD measurement principle, and the uncertainty calculation of well trajectory is discussed on the basis of ISCWSA error model; the algorithm is analyzed and designed, and the modeling process is given; Using Python as the programming language, the visualization software of well trajectory uncertainty is developed, which realizes the visualization of well trajectory and the visualization analysis of three-dimensional error ellipsoid of well trajectory uncertainty, and can directly see the size of well trajectory error and the trend of well progress; In the artificial island of Jidong Oilfield, the construction of slave well group with minimum anti-collision distance of 2.6 meters was completed. It provides a good theoretical reference for the wellbore anti-collision and wellbore trajectory control.
Study on the Applicability of a New Type of Bit in Ordovician - Cambrian Dolomite Formation of Tarim Basin
Authors: Liu Hongtao , Yang Chengxin , Zhou Jian , Wang Xiaoliang , Ding Feng , Song Guozhi
Published: July 2021

The Ordovician-Cambrian reservoirs in Tarim basin are characterized by complex geological structure, deep reservoir, and thick dolomite strata in the middle and deep formation. The dolomite formation is characterized by large content of chert, high dense lithology, high uniaxial compressive strength, prominent impact and heterogeneity of the formation, it was difficult for conventional drill bits to form stable effective cutting depth and prone to vortex damage, which leads to short drill footage, low ROP and long drilling cycle, it seriously restricted the efficient exploration and development of Cambrian subsalt reservoirs in this block. Therefore, experimental analysis of rock mechanics in the Cambrian dolomite formation was carried out to quantitatively evaluate the rock mechanics properties in this area. A new type of PDC bit was designed to improve the impact resistance and eddy resistance of single teeth, and the impact fatigue test was carried out and successfully applied in the field. The research results show that compared with the adjacent wells in the same interval and lithology, the footage is increased by 39%, and the ROP is increased by 84%, which has achieved obvious acceleration effect, providing technical reference and support for the efficient exploration and development of Cambrian pre-salt reservoirs in the Tarim Basin.
Study and Application on ROP-Enhancing Technology of Ordovician-Cambrian Dolomite Strata in Tarim Basin
Authors: Zhou Bo , Liu Yong , Liu Huiliang , He Renqing , Lu Hui , Zhang Chongyuan
Published: July 2021

The Ordovician-Cambrian dolomite formation in Tarim basin has certain characteristics such as poor drillability, long drilling cycle, difficulty in selecting drill bit and accelerating tool. In order to meet the requirements of efficient exploration and development of Cambrian oil and gas reservoirs, there is an urgent need to design high ROP bit and acceleration tool suitable for dolomite formation, optimize drilling parameters and improve ROP to form the technical scheme of drilling acceleration in dolomite formation. Therefore, the drillability of the Cambrian dolomite strata was studied. The experimental analysis was carried out according to the geological characteristics and rock mechanical parameters. Dual index drillability analysis method was used to evaluate the formation compactness, abrasiveness and other formation drillability characteristics. A new type of PDC bit was designed to improve the impact resistance and eddy resistance of single tooth, a three-dimensional vibration acceleration tool was selected to reduce the vibration of the bit, and combined with the optimization of drilling parameters, the technical scheme for acceleration of the Ordovician -Cambrian dolomite formation in Tarim Basin was finally formed, which was successfully field tested in Well A of Tarim Basin. The research results show that compared with the adjacent well B section, the average footage and the average ROP are increased by 47.8% and 32.0% respectively. Compared with the adjacent well C section, the average footage and average ROP increased by 37.0% and 29.5% respectively. The results provide technical reference and support for the efficient exploration and development of Ordovician - Cambrian reservoirs in Tarim Basin.
Study on the geological stress sensitivity of weak geotechnical engineering in the Three Gorges reservoir area
Authors: Qin Yujia , Tang Xin , Cheng Longfei , Guo Yuanchen , Yao Lei , Li Bin
Published: July 2021

Soft rock has the characteristics of poor engineering mechanics, and it is easy to change under the action of water or external load. This paper uses the pulse attenuation permeability meter to develop permeability test and coefficient of variation for weak rock with common engineering mechanical properties. Calculate and explore the geological stress sensitivity characteristics of weak rock engineering within the Three Gorges reservoir area. The conclusions are as follows: the permeability of weak rock in the Three Gorges reservoir area is less than 0.1mD, which belongs to the type of compact soft rock, among which the permeability of medium sandstone (0.048mD)> the permeability of fine sandstone (0.0055mD)> the permeability of mud shale (0.0047mD); the rock permeability coefficient of variation is greater than 0.7, with a strong heterogeneity. The permeability of soft rock has obvious anisotropy. The permeability of the vertical layer of medium-fine sandstone and silty mudstone is greater than the permeability parallel to the plane. The difference between the two is closely related to the physical difference between different lithologies. The permeability of siltstone, shale and sandstone rocks decreases exponentially with the increase of effective stress. The relationship between the permeability loss rates of various types of rock is: shale> siltstone> sandstone, indicating the same stress condition, page Rocks have higher stress sensitivity than siltstones and sandstones. This is mainly because the fractures in sandstone and siltstone are more developed than shale.
Soil Remediation and Construction Technology of Prefabricated Building Sleeve Grouting in Eco-city
Authors: Huo Tingting
Published: July 2021

The construction technology of prefabricated structure sleeve grouting is an advanced construction technology focusing on energy conservation and environmental protection, it can reduce the waste of resources and environmental pollution at the same time,and it also can greatly improve the quality and efficiency of construction by running a variety of construction procedures simultaneously.The author analyzes the sleeve grouting construction of the assembled structure, and puts forward some key technologies of grouting construction and control methods of heavy and difficult points in grouting construction, in order to provide reference for the majority of engineering construction personnel.