bluuebunny/crossref_metadata_2025 huggingface dataset:
1H-Benzimidazole-5-carboxamidine derivatives: design, synthesis, molecular docking, DFT and antimicrobial studies
Authors: Erol Meryem , Celik Ismail , Temiz-Arpaci Ozlem , Goker Hakan , Kaynak-Onurdag Fatma , Okten Suzan
Published: November 2020

15 new 1H-benzimidazole-5-carboxamidine derivatives were synthesized, their antimicrobial effects were evaluated, and molecular docking and DFT studies were performed.
One-pot kinetic resolution–Mitsunobu reaction to access optically pure compounds, using silver salts in the substitution protocol
Authors: Raval Hiten B. , Bedekar Ashutosh V.
Published: November 2020

Racemic carbinols were converted to chirally pure acetates by a combination of one-pot, enzyme mediated KR and Mitsunobu reaction with metal acetates. Use of AoNO3 or mixture with NaOAc gave excellent results. The protocol is further extended to introduce azide in place of acetate.
Enantioseparation by high-performance liquid chromatography on proline-derived helical polyacetylenes
Authors: Shi Ge , Dai Xiao , Xu Qian , Shen Jun , Wan Xinhua
Published: November 2020

The nature, size, and position of the substituent on the phenyl ring remarkably influence the enantioseparation performance of polyacetylene-based CSPs.
Synthesis of dihydroisoindolo[2,1-a]quinolin-11-ones, their in silico ADMET properties and in vitro antitumor activities
Authors: Merchán-Arenas Diego R. , Sojo Felipe , Arvelo Francisco , Kouznetsov Vladimir V.
Published: November 2020

We synthesized a series of dihydroisoindolo[2,1-a]quinolin-11-ones using the imino Diels–Alder reaction and evaluated their biological properties, finding a new hit in anticancer research.
Non-ionic small amphiphile based nanostructures for biomedical applications
Authors: Parshad Badri , Prasad Suchita , Bhatia Sumati , Mittal Ayushi , Pan Yuanwei , Mishra Prashant Kumar , Sharma Sunil K. , Fruk Ljiljana
Published: November 2020

Amphiphiles in action: self-assembled nanostructures for drug delivery and imaging.
Tailored surface composition of Au/Pt nanocatalysts synthesized in microemulsions: a simulation study
Authors: Pérez-Álvarez Jorge , Tojo Concha , Buceta David , López-Quintela M. Arturo
Published: November 2020

Pure Pt surface at low Au content and mixed surface at high Au content.
Irregular solution thermodynamics of wood pulp in the superbase ionic liquid [m-TBDH][AcO]
Authors: Driver Gordon W. , Kilpeläinen Ilkka A.
Published: November 2020

Thermochemical analysis of cellulose dissolution character in the superbase containing protic ionic liquid [m-TBDH][AcO] reveals lower critical solution temperature (LCST) behaviour.
When are two hydrogen bonds better than one? Accurate first-principles models explain the balance of hydrogen bond donors and acceptors found in proteins
Authors: Vennelakanti Vyshnavi , Qi Helena W. , Mehmood Rimsha , Kulik Heather J.
Published: November 2020

Correlated wavefunction theory predicts and high-resolution crystal structure analysis confirms the important, stabilizing effect of simultaneous hydrogen bond donor and acceptor interactions in proteins.
Porous polymeric membranes: fabrication techniques and biomedical applications
Authors: Shiohara Amane , Prieto-Simon Beatriz , Voelcker Nicolas H
Published: November 2020

Porous polymeric membranes have shown great potential in biological and biomedical applications such as tissue engineering, bioseparation, and biosensing, due to their structural flexibility, versatile surface chemistry, and biocompatibility.
Sparse LMS algorithm for two‐level DSTATCOM
Authors: Mangaraj Mrutyunjaya , Panda Anup Kumar
Published: November 2020

Sparse least mean square algorithm is proposed for the DSTATCOM as an optimal current harmonic extractor to cope with the intermittent nature of loadings. Sparse least mean square is the improved version of adaptive least mean square learning mechanism with regards to sparsity. This innovative approach is utilized for better parameter estimation due to its algorithmic simplicity and parallel computing nature. Hence, sparse least mean square is expected to reduce the computation and storage requirements significantly. This suggested controller consists of six subnets. Three subnets for active and another three for reactive weight component are used to extract the fundamental component of the load current. Several factors like previous weight, normalizing weight and learning rate are involved in the sparse least mean square based weight‐updating rule to have better dynamic performance, reduced computational burden and better estimation speed etc. The detailed control algorithm is formulated using MATLAB/Simulink, and validated using experimental analysis. Among these two algorithms, the sparse least mean square offers better voltage regulation, voltage balancing, source current harmonic reduction and power factor correction under various loading scenarios.
VLA ammonia observations of L1287
Authors: Sepúlveda Inma , Estalella Robert , Anglada Guillem , López Rosario , Riera Angels , Busquet Gemma , Palau Aina , Torrelles José M. , Rodríguez Luis F.
Published: November 2020

Aims. In this paper, we study the dense gas of the molecular cloud LDN 1287 (L1287), which harbors a double FU Ori system, an energetic molecular outflow, and a still-forming cluster of deeply embedded low-mass young stellar objects that show a high level of fragmentation.

Methods. We present optical Hα and [SII], and VLA NH3 (1, 1) and (2, 2) observations with an angular resolution of ~3′′.5. The observed NH3 spectra have been analyzed with the Hyperfine Structure tool, fitting simultaneously three different velocity components.

Results. The NH3 emission from L1287 comes from four different structures: a core associated with RNO 1, a guitar-shaped core (the Guitar) and two interlaced filaments (the blue and red filaments) roughly centered toward the binary FU Ori system RNO 1B/1C and its associated cluster. Regarding the Guitar core, there are clear signatures of gas infall onto a central mass that has been estimated to be ~2.1M⊙. Regarding the two filaments, they have radii of ~0.03 pc, masses per unit length of ~50M⊙ pc−1, and are in near isothermal equilibrium. A central cavity is identified, probably related with the outflow and also revealed by the Hα and [SII] emission, with several young stellar objects near its inner walls. Both filaments show clear signs of perturbation by the high-velocity gas of the outflows driven by one or several young stellar objects of the cluster. The blue and red filaments are coherent in velocity and have nearly subsonic gas motions, except at the position of the embedded sources. Velocity gradients across the blue filament can be interpreted either as infalling material onto the filament or rotation. Velocity gradients along the filaments are interpreted as infall motions toward a gravitational well at the intersection of the two filaments.
Reliability of real-time RT-PCR tests to detect SARS-Cov-2: A literature review
Authors: Bezier Clément , Anthoine Géraldine , Charki Abdérafi
Published: November 2020

In the face of the COVID-19 (Coronavirus Disease 2019) pandemic, the World Health Organization (WHO) has urged countries to test the population more widely. Clinical laboratories have been confronted with a huge demand for testing and have had to make urgent preparations for staff training, to establish new analytical processes, reorganize the workspace, and stock up on specific equipment and diagnostic test kits. The reliability of SARS-Cov-2 test results is of critical importance, given the impact it has on patient care and the management of the health crisis. A review of the literature available for the period leading up to and including June 2020 on the reliability of SARS-Cov-2 (Severe Acute Respiratory Syndrome Coronavirus) detection methods using real-time RT PCR (Reverse Transcription - Polymerase Chain Reaction) brings together the primary factors teams of scientists claim or demonstrate to affect the reliability of results. A description is given of the RT-PCR testing method, followed by a presentation of the characteristics and validation techniques used. A summary of data from the literature on the reliability of tests and commercial kits for SARS-Cov-2 detection, including current uncertainties with regard to the molecular targets selected and genetic diversity of SARS-Cov-2 is provided. The limitations and perspectives are then discussed in detail in the light of the bibliographic data available. Many questions have been asked that still remain unanswered. The lack of knowledge about this novel virus, which appeared at the end of 2019, has a significant impact on the technical capacity to develop reliable, rapid and practical tools for its detection.
Simple experimental setup for double-pulse and two-dimensional terahertz spectroscopy
Authors: Knighton B. E. , Sorenson S. A. , Johnson J. A.
Published: November 2020

In the growing field of high-field terahertz (THz) spectroscopy, many ultrafast research labs are equipped to perform single-pulse (one-dimensional) THz measurements. We describe a simple and versatile method to modify one-dimensional THz experimental setups to generate two variably delayed THz pulses. This method optimizes the use of pump power to create two high-field THz pulses. Adding only a beam splitter and delay stage, research groups can access the wealth of information only available through two-dimensional (2D) measurements. We also provide useful guidance to those new to some challenges of 2D THz spectroscopy.
Understanding how non-condensable gases modify cavitation mass transfer through the van der Waals theory of capillarity
Authors: Mukherjee Saikat , Gomez Hector
Published: November 2020

Cavitation of a pure fluid continues to be a challenging problem in fluid dynamics. However, most cavitating fluids contain small amounts of non-condensable gases that can change the dynamics of the process significantly. While the effect of non-condensable gases on the surface and bulk properties of the fluid has been studied in detail, its impact on liquid–vapor mass transfer has remained elusive. Here, we provide mechanistic insight into this process using theory and simulations. Our results point to a dual role of non-condensable gases on liquid–vapor mass transfer. While the presence of non-condensable gases always reduces hydrodynamic cavitation, it also leads to a mass transfer mechanism that we call mixing cavitation. We show that mixing cavitation may increase or reduce mass transfer under different physical conditions and can dominate hydrodynamic cavitation. This study opens possibilities to better understand cavitation inception.
Spontaneous adsorption of ions on graphene at the electrolyte–graphene interface
Authors: Sun Jianbo , Camilli Luca , Caridad José M. , Santos Jaime E. , Liu Yuxin
Published: November 2020

We report the spontaneous adsorption of ions on graphene at the interface with electrolytes through an investigation based on the electrolyte-gated field effect transistor configuration. It is found that the gate voltage at which the minimum conductivity occurs in these devices is highly sensitive to the type of ions and their concentrations in the electrolytes; yet the experimental results exhibit non-trivial deviations from the predictions based on the Gouy–Chapman–Stern (GCS) model, which only takes account of the electrostatic interactions among the charges in the system. By incorporating a Langmuir-type adsorption term into the GCS model, we achieve quantitative alignment with the experiments, thus demonstrating that these deviations originate from the spontaneous adsorption of ions onto graphene. Analysis of the transport characteristics in these devices indeed confirms the existence of the adsorbed ions.
Ferroelectric properties of HfO2 nanodots with a diameter smaller than 10 nm deposited on an ITO bottom electrode
Authors: Shin Hyun Wook , Son Jong Yeog
Published: November 2020

HfO2 nanodots and epitaxial HfO2 thin films with ferroelectric properties were grown on yttria-stabilized zirconia substrates with indium tin oxide bottom electrodes via a pulsed laser deposition (PLD) method. The crystallinity and ferroelectric properties of the epitaxial HfO2 thin films were analyzed to compare ferroelectric properties resulting from crystallinity and the strained structure of HfO2 nanodots. Using the total number of PLD pulses as a control, it was possible to grow HfO2 nanodots with diameters of 7, 12, and 20 nm and heights of 4.9, 7.8, and 14.8 nm. Based on the d33 piezoelectric hysteresis loops and polarization switching phenomena, it was confirmed that the HfO2 nanodots exhibited good ferroelectric properties even for scaling of less than 7 nm in diameter. The observation of the piezoelectric d33 hysteresis loop of the HfO2 nanodots and epitaxial HfO2 thin films revealed that HfO2 nanodots had improved ferroelectric properties due to the size effect.
Exciton transfer using rates extracted from the “hierarchical equations of motion”
Authors: Seibt Joachim , Kühn Oliver
Published: November 2020

Frenkel exciton population dynamics of an excitonic dimer is studied by comparing the results from a quantum master equation involving rates from second-order perturbative treatment with respect to the excitonic coupling with the non-perturbative results from “Hierarchical Equations of Motion” (HEOM). By formulating generic Liouville-space expressions for the rates, we can choose to evaluate them either via HEOM propagations or by applying the cumulant expansion. The coupling of electronic transitions to bath modes is modeled either as overdamped oscillators for the description of thermal bath components or as underdamped oscillators to account for intramolecular vibrations. Cases of initial nonequilibrium and equilibrium vibrations are discussed. In the case of HEOM, initial equilibration enters via a polaron transformation. Pointing out the differences between the nonequilibrium and equilibrium approach in the context of the projection operator formalism, we identify a further description, where the transfer dynamics is driven only by fluctuations without involvement of dissipation. Despite this approximation, this approach can also yield meaningful results in certain parameter regimes. While for the chosen model, HEOM has no technical advantage for evaluation of the rate expressions compared to cumulant expansion, there are situations where only evaluation with HEOM is applicable. For instance, a separation of reference and interaction Hamiltonian via a polaron transformation to account for the interplay between Coulomb coupling and vibrational oscillations of the bath at the level of a second-order treatment can be adjusted for a treatment with HEOM.
Current suppressed self-compliance characteristics of oxygen rich TiOy inserted Al2O3/TiOx based RRAM
Authors: Kim Sungjoon , Kim Tae-Hyeon , Kim Hyungjin , Park Byung-Gook
Published: November 2020

Although many studies have been continuously conducted to reduce the power consumption of a resistive random access memory (RRAM) cross-point array with the current-compliance effect, it has been difficult yet to realize intrinsic self-compliance effects in an RRAM device itself. In this study, a simple oxygen-rich TiOy layer is inserted into the Al2O3/TiOx-based RRAM stack as a current suppression layer, and XPS analysis is provided to compare the stoichiometry of the TiOx and TiOy layers. A self-compliance region is formed between the different breakdown voltages of Al2O3 and TiOy layers, and a relatively thinner current path is formed in the Al2O3 layer than a device without the TiOy layer and the overall current level is significantly decreased since the TiOy layer limits the overshoot current.
Quantitative characterization of dielectric properties of nanoparticles using electrostatic force microscopy
Authors: Descoteaux Marc , Sunnerberg Jacob P. , Staii Cristian
Published: November 2020

We use a new method based on Electrostatic Force Microscopy (EFM) to perform quantitative measurements of the dielectric constants of individual carboxylated as well as non-functionalized polystyrene nanospheres. The EFM data record the oscillation phase of an atomic force microscope (AFM) cantilever as a function of the AFM tip position. In our experiments, the relative dielectric constant of the sample is measured from the EFM phase shifts vs the tip–surface separation, according to a simple analytical model describing the tip–surface interactions. We perform a comprehensive study of how the dielectric constant depends on the sphere diameter for both types of nanospheres. Our results demonstrate that the experimental method has a high-resolution for measuring the dielectric constant of nano/microbeads and other nanoscale materials and is simple to implement on standard atomic force microscopes. This non-invasive technique can be applied to measure the electrical properties of colloidal particles, polymers, interphases, and polymer nanocomposites.
The Young–Laplace equation for a solid–liquid interface
Authors: Montero de Hijes P. , Shi K. , Noya E. G. , Santiso E. E. , Gubbins K. E. , Sanz E. , Vega C.
Published: November 2020

The application of the Young–Laplace equation to a solid–liquid interface is considered. Computer simulations show that the pressure inside a solid cluster of hard spheres is smaller than the external pressure of the liquid (both for small and large clusters). This would suggest a negative value for the interfacial free energy. We show that in a Gibbsian description of the thermodynamics of a curved solid–liquid interface in equilibrium, the choice of the thermodynamic (rather than mechanical) pressure is required, as suggested by Tolman for the liquid–gas scenario. With this definition, the interfacial free energy is positive, and the values obtained are in excellent agreement with previous results from nucleation studies. Although, for a curved fluid–fluid interface, there is no distinction between mechanical and thermal pressures (for a sufficiently large inner phase), in the solid–liquid interface, they do not coincide, as hypothesized by Gibbs.
Chinese degraded grasslands – pathways for sustainability
Authors: Kemp David R. , Behrendt Karl , Badgery Warwick B. , Han Guodong D. , Li Ping , Zhang Yingjun , Wu Jianping , Hou F. J.
Published: November 2020

The 400m ha of grazing lands in China, mainly across the north and west of the country, have similar problems to those throughout the steppe of Mongolia, Central Asia and neighbouring countries. The grasslands are in drier regions (50–500mm) across mainly Inner Mongolia, Xinjiang, Tibet, Qinghai, Gansu and Sichuan, often at higher altitudes on the Tibetan, Mongolian and Loess Plateaus, and have for millennia supported the livelihoods of millions of herders. By 2002, surveys were classifying 90% of the grasslands as degraded. Less than 10% were considered desertified to the extent that replanting was the only option to restore some plant cover. The majority of the grasslands were considered capable of being rehabilitated to some degree through changing management practices. In the 1980s the first Grassland Laws were promulgated, initiating a series of programs aimed at rehabilitating the grasslands. These programs included the establishment of individual ‘user rights’ to herders to use a defined area of grassland and the imposition of grazing bans, often for five years, to rehabilitate degraded areas. These were often applied at a regional level. At the same time, herders were encouraged to have more livestock as that was seen as a pathway to lift them from poverty. The sheep equivalent of grazing animals for the whole of China, has increased 4-fold since 1949, often by greater amounts in some regions. But there was very limited work done on how best to manage grazing livestock in ways that could aid grassland rehabilitation. In the early 2000s a collaborative program was started between several Australian and Chinese Institutes, to investigate better ways of rehabilitating the grasslands and to improve herder incomes from livestock. This work involved the development of four models that could use the limited data available, to help guide a series of research programs. These models indicated that halving stocking rates could maintain or increase herder net incomes. Farm demonstrations showed this result applied in practice and grasslands did improve. A series of grazing experiments found that halving the current stocking rates was needed to enable the survival of the better plant species within the grassland. A model that estimated the net value of each animal indicated that often half the animals were generating marginal or negative incomes, and could be culled without affecting the household income, again substantiated in farm demonstrations. In this paper, the causes of degradation, which can be traced back to the progressive changes that have occurred in China since 1949, are discussed together with the practice changes that have come from a large collaborative research program between Australia and China. Efficient markets and land tenure reform are needed to help create the incentives for herders to change in sustainable ways.
Impact of dung beetle activity on the quality of water percolating through Allophanic soil
Authors: Aislabie Jackie , McLeod Malcolm , McGill Alexandra , Rhodes Phillippa , Forgie Shaun
Published: November 2020

Dung beetles are described as key ecosystem service providers. Because of ecosystem benefits from their activity, approval has been granted to import dung-burying beetles for release into pasture systems in New Zealand. Concerns remain, however, about the impact of dung beetle tunnelling and burying activity on the leaching of contaminants through soil. To assess the quality of water leaching from soil cores containing dung beetles, a trial was conducted using 12 intact Allophanic soil core lysimeters under in situ soil moisture and temperature regimes. Four lysimeters received dung and beetles (Geotrupes spiniger and Onthophagus taurus), four received dung and no beetles and four (controls) received no dung and no beetles. The quality of water was assessed by monitoring leachate samples for Escherichia coli and total N and P for 6 months. Key findings of the study were that concentrations of E. coli, N and P leaching through the lysimeters treated with dung beetles were not significantly different from soils without dung beetles. In addition, where dung was buried there was a significant decrease in E. coli and total N and P in surface soil compared with the lysimeters receiving dung only. Results from this study suggest dung beetle tunnelling and burying activity does not negatively impact the quality of water leaching through Allophanic soil.
mGreenLantern: a bright monomeric fluorescent protein with rapid expression and cell filling properties for neuronal imaging
Authors: Campbell Benjamin C. , Nabel Elisa M. , Murdock Mitchell H. , Lao-Peregrin Cristina , Tsoulfas Pantelis , Blackmore Murray G. , Lee Francis S. , Liston Conor , Morishita Hirofumi , Petsko Gregory A.
Published: November 2020

Significance

We have developed a fluorescent protein, mGreenLantern, that features exceptionally high brightness in mouse, bacterial, and human cells (up to sixfold brighter than EGFP) and have demonstrated its superior ability to highlight neuronal morphology compared to EGFP and EYFP. Screening fluorescent protein mutants based on whole-cell brightness while evaluating expression kinetics in lysate enabled us to identify variants exhibiting striking divergences between their computed spectroscopic brightness and actual performance in cells. mGreenLantern additionally features unusually high chemical and thermodynamic stability and is compatible with existing GFP filter sets, excitation sources, commercial EGFP antibodies, expansion microscopy, and whole-brain tissue clearing. Our hypothesis-driven engineering strategy represents a generalizable method with great potential to enhance the performance of constitutive reporters and GFP-based biosensors.
Current methods for GaN synthesis and the limitations
Authors: Wang Yuguo
Published: November 2020

The application of GaN has greatly enhanced the performance of optoelectrical and microelectronic devices. However, the industrial application still faces huge challenges due to the difficulty during the synthesis process. This paper introduces several current methods for GaN synthesis and talks about their advantages and limitations. Four methods are introduced: high pressure nitrogen solution growth process, ammonothermal method, sodium flux process and hydride vapor phase epitaxy. As a result, they are only suitable for specific use like scientific research and can’t be used for massive production. This paper reviews main GaN synthesis methods and points out the limitations they have to overcome for commercial applications.
Antioxidant Activity of the Extracts from Tussilago farfara
Authors: Wei Xiang , Shang Huilan , Yang Aimei , Wang Zhihui
Published: November 2020

Objective: The antioxidative properties of Chinese medicine Tussilago farfara were determined by spectrophotometry. Methods: The anti-oxidation activity of petroleum ether, ethyl acetate and n-butanol extracts from ethanol extract of Tussilago farfar were studied, using DPPH free radical scavenging, hydroxyl radical scavenging, and total reducing power determination. Results: Compared with the Vc activity of the positive control, the extracts of ethyl acetate part and the n-butanol part showed significant antioxidant activity, and the antioxidant activity in the ethyl acetate part was higher than Vc. Conclusion: Antioxidant activity of ethyl acetate extract is better than vitamin C, N-butanol extract also has obvious antioxidant activities.
Analysis on Research Status of Loess Microstructure
Authors: Xie Xiao , Wei Yulu
Published: November 2020

Chinese loess has a wide range of distribution, large strata thickness, and high stratigraphic completeness, and has been widely studied by scholars. By consulting and summarizing literatures, this paper generalizes the previous research results, and summarizes the microstructure characteristics of the loess, such as loess skeleton particles, the way they are connected to each other, the pore types, and the regional changes of the loess microstructure. Finally, the prospects of relevant researches on the loess microstructure were prospected.
Effect of Glaze Composition on the Impact Resistance of Glass Lining of Glass-Lined Vessels
Authors: Xu Jinsha , Ren Facai , Liu Chongyang , Tang Chenhuai , Han Shoupeng , Chen Yi , Song Youli , Lin Jinfeng
Published: November 2020

Glass-lined pressure vessels are widely used in various corrosion conditions because of their excellent corrosion resistance. However, mechanical impact is the most common failure mode of glass linings due to its brittleness. Under the same firing process condition, the impact-resistant properties of glass-lined vessels are largely dependent upon the glaze composition. In this paper, three kinds of glazes were selected to study the impact resistance of the glass lining. Based on the glaze composition analysis, the impact energy measurement and the micromorphology observations of the impact surfaces, the effect of glaze composition on the impact resistance of glass lining was discussed. The results showed that the low content of refractory oxides such as SiO2, ZrO2 and Al2O3 made the glaze easy to melt and with high-temperature fluidity. Therefore, the structure of the glass lining was dense, and glass lining exhibited good resistance to impact.
A study on the Friction Stir Welded Non-ferrous Alloy
Authors: Xu Anlian
Published: November 2020

Friction stir welding (FSW), which is a new-type solid state welding technology, has been successfully used in aluminum alloys, magnesium alloys and coppers. To study the properties of friction stir welded zinc-based non-ferrous alloys, Zn-0.5Cu alloy plates were butt welded by FSW. The results show that Zn-0.5Cu alloy plates with 5 thickness can be successfully welded by FSW. The joint efficiency of weld joint can reach over 95 % at appropriate weld process parameters.
Research on Large-diameter Solid Expandable Tubular Subsidy Technology and Suspension Seal Device
Authors: Fu Daqi , Zhu Xiaohua , Qi Yuekui , Shao Lifei , Shi Changshuai , Chen Kailin , Huang Manlinag , Zhao Tao
Published: November 2020

In view of the issue that the diameter is small and the suspension force is uncertain after solid expandable tubular (SET) subsidy. The uniaxial tensile test of SA106B metal is carried out, and the parameters of metal elastoplastic constitutive model are fitted accordingly. Then, a solid expandable tubular laboratory test is designed, and a finite element model of SET is established based on this test. Finally, the effects of the expansion cone radius and the thickness of the rubber ring on the expansion stress and contact pressure are researched. The results show that the established finite element model has small errors and reliable results. The optimal expansion cone radius is selected through the maximum stress and the residual stress of expanded tubular to improve the expansion quality of the tube. The thickness of the rubber ring has a great influence on the contact pressure and the suspension force, so it must be reasonably optimized under the premise of ensuring the sealing ability. The optimal solution of the expansion cone radius and the thickness of the rubber ring is given by comparison. This study provides a theoretical basis for the optimization of solid expandable tubular technology.
Progressive damage analysis and failure load of ceramic matrix composite hollow-shaft
Authors: Zhang Chengcheng
Published: November 2020

Composite damage is one of important reasons for the destruction of engineering structures; therefore the research target is a typical engineering component – hollow shaft. Firstly, based on the continuum damage mechanics, a stiffness degradation method is proposed to simulate the progressive damage process of ceramic matrix composite hollow-shaft. Afterwards, program development using solid finite element method in ANSYS, the simulative load–displacement curves and tensile failure load of the hollow-shaft are achieved. Finally, Qualitative and quantitative analysis by computer calculation and experimental results, successfully predict the structure failure modes and bearing capacity under axial load. This work proves that the correctness and feasibility of this progressive damage analysis method for ceramic matrix composite hollow-shaft, and further deepen the understanding of damage development.
Main Components and Neuroanalysis of Automatic Steel Water Deoxygenation Alloy Ingredients
Authors: Zhang Maoyi
Published: November 2020

At present, how to establish a mathematical model of deoxygenation alloying link through historical data, predict and optimize the type and quantity of alloy input online, and minimize the production cost of alloy steel while ensuring the quality of steel and water. It is an important issue for major steel companies to improve their competitiveness. Based on the main component and neural network and multivariate nonlinear regression theory, based on the existing alloy historical data, this paper optimizes the ingredients scheme of "deoxygenation and alloying" of steel and water, establishes the mathematical model, calculates the historical harvest rate of the main elements, and predicts the historical harvest rate of the main elements. Combined with the price of the alloy, the automatic ingredient scheme of the steel water deoxygenated alloy is given, and the cost of the steel water deoxygenated alloy is optimized.
Comparison on Mechanical Property of PLA/PBAT Film under Simulate Weathering Tests
Authors: Guo Cheng HAN , Rui GUO , Zhao Hui YU
Published: November 2020

The mechanical property changes of PLA/PBAT packaging films under different weathering tests were conducted. After manufactured by plant-size equipment, the tensile strength, elongation rate and tearing strength of printed/non-printed fully-biodegradable packaging films were evaluated after eight-days testing under different weathering conditions including xenon-lamp aging, salt spraying, cooling and freezing, simulating the use of commercial fully-degradable bags in outdoor environment, ocean or coast environment, and in the ice chest of supermarkets. The results demonstrate that printing process led to a decrease of mechanical properties of the fully-biodegradable films. Moreover, the weathering tests had remarkable negative impact on the toughness of fully-biodegradable films, and had large impact on the tearing resistance of the films, while the strength of films were less influenced. Additionally, the low-temperature conditions show less influence on the mechanical properties of fully-biodegradable films, and the high salinity and high humidity environment exhibits tremendous impact on the fully-biodegradable films. The proposed research demonstrates the capability of commercial fully-biodegradable films for different application scenarios, as well as the referrible disposal treatment for fully-biodegradable films.
Application of Forged N6
Authors: Li Yong , Duan Hongtao , Li Chunlei , Wang Yi
Published: November 2020

N6 has excellent performance and obvious advantage in forging. Through mechanical test and metallographic analysis, the process parameters are verified, and the life and safety of the machine are greatly improved.
General Eigensolutions for 2D Viscoelastic Materials
Authors: Yan GF , Zhang WX
Published: November 2020

In recent years, viscoelastic materials have been widely used in industry, and the study of its mechanical properties has become the key of modern science and engineering. In this paper, based on Laplace integral transformation, a new analytical method is proposed to solve the mechanical problems related to viscoelastic materials. According to the variational principle and the method of separating variables, the governing equations of the basic problems are established, and all the eigensolutions of analytical forms are obtained. In the numerical calculation, the relationship between these eigensolutions and boundary conditions is studied systematically, and the time-dependent property of viscoelastic materials is well described.
Stability analysis and risk assessment of a landslide in southwest of China
Authors: Lv Qingchao , Zhou Heng , Di Shengjie
Published: November 2020

In this paper, a risk assessment method based on limit equilibrium method is proposed. It has been used to estimate the risk of forming wedge body in a landslide in southwest of China. According to the monitoring data and the result of stability analysis using limit equilibrium method and three-dimensional finite element method, we find that due to the rising of water table, the landslide tends to limit-equilibrium state. The displacement under normal condition is consistency with that of monitoring. It is possible to slide under dynamic condition, but the landslide cannot block the river totally. The research achievements have been used to make contingency planning and are of great significance.
Preparation and Flame Retardancy of Hydrotalcite/Montmorillonite Nanocomposite
Authors: Wang Han , Huang Wuji , Yang Lang
Published: November 2020

Layered nanocomposite hydrotalcite/montmorillonite (LDH/MMT) was obtained though in-situ synthesis of nickel-magnesium-aluminum hydrotalcite (Ni-Mg-Al LDH) on the surface of montmorillonite nanosheets (MMTNS) by one-step hydrothermal method. X-ray diffractometer (XRD), Fourier Transform Infrared Spectrometer (FTIR), Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM) were used to characterize the composite material. The flame retardancy property of the composite was investigated by thermogravimetry (TG) and cone calorimeter (Cone). The results show that both the hydrotalcite and montmorillonite nanosheets have a lamellar structure; LDH/MMT composite has better thermal stability than that of hydrotalcite or montmorillonite alone, and the flame retardant effect of LDH/MMT on polystyrene (PS) is more obvious. The composite material can reduce the maximum heat release rate of polystyrene during combustion by 14.8%.
Catalytic Oxidation of Toluene over Manganese and Cerium Complex Oxide Supported on Zeolite
Authors: Wang Keliang , Liu Xiuzhen , Tu Shunheng , Zhang Le , Jiang Chan , Li Wen , Ye Daiqi
Published: November 2020

The air pollution caused by VOCs emssions has drawn considerable attention in recent years. Many catalyst systems with excellent activity were studied for the catalytic oxidation of VOCs. In this work, using air containing toluene as the simulation of industrial emissions, MnOx-CeO2/Powder zeolite and MnOx-CeO2/Honeycomb zeolite catalyst samples prepared by the isometric impregnation method were studied for catalytic performance of toluene. The catalysts were characterized by SEM, BET, XRD, SEM, H2-TPR and O2-TPD. The research results obtained showed that MnOx-CeO2/Powder zeolite catalysts exhibited better activity than MnOx-CeO2/Honeycomb zeolite catalyst at lower temperatures, the MnOx-CeO2/Powder zeolite catalyst presented better catalytic performance with T50=223°Cand T99=275°Cunder the condition of GHSV of 15000h−1 and toluene concentration of 100ppm, which is 23°Cand 47°Clower than MnOx-CeO2/Honeycomb zeolite, respectively. The characterization results also indicated that the catalytic activity was relavant closely with specific surface area, active oxygen species, catalyst morphology and valence of manganese and cerium oxides. Also, the catalyst has an excellent stability in the catalytic combustion towards toluene.
Study on seismic performance of frame structure with viscous damping staircase
Authors: Changren Ke , Hanqin Wang
Published: November 2020

Based on the significant energy dissipation performance of the viscous damper, the force-displacement hysteresis curve is full and the Maxwell mechanical model has a weak dependence on vibration frequency. Combining the failure mode of the staircase damage with the Maxwell mechanical model, this paper proposes an earthquake-resistant frame staircase model with damped bearings. A finite element analysis of a nine-story reinforced concrete structure is performed using SAP2000. By setting three different connection methods on the staircase structure, the similarities and differences of different staircase structures to the input seismic wave feedback are analyzed to compare the advantages and disadvantages of its seismic performance.
Effect of Thermodynamic Factors on Colloid Stability
Authors: Chen Zhengxian
Published: November 2020

Colloid is more and more widely used in daily life. No matter medical application, or food additive in the food industry, or electrolyte in the lead battery, all are deeply connected with it. Among them, the stability of colloid is an important direction for people to explore. According to DLVO theory, the stability of colloid is determined by the height of energy barrier. In this paper, the effect of temperature on colloid aggregation or sedimentation will be discussed by calculating and observing the settling process of colloid. This paper will also put forward the optimum temperature position to keep the highest energy barrier height and the way to estimate the value of energy barrier by reaction, which gives new possibilities for controlling colloid stability.
Research on Application of RPC Materials in Urban Pedestrian Bridge Reconstruction
Authors: Lyu Ping , Long Peiheng
Published: November 2020

Aiming at the characteristics of poor corrosion resistance, high maintenance frequency and high cost of steel box girder pedestrian bridge structure, and the traditional concrete is thick and moderate in strength, this paper proposes a method to apply reactive powder concrete RPC to the existing pedestrian bridge deck and uses steel-RPC composite box girder as the bridge superstructure. Based on the research on the RPC material and the related performance of its components, the feasibility and reliability of RPC applied to beam-slab composite members are verified. By comparing steel-RPC composite box girder, steel box girder, and steel-general concrete composite box girder, it is found that steel-RPC composite box girder is superior in terms of mechanical performance, economic evaluation, and aesthetics. The research shows that the steel-RPC composite box girder is more suitable for the steel box girder pedestrian bridge reconstruction project and the new pedestrian bridge project across urban roads.
Design of rotor profile of a new roots vacuum pump
Authors: Liu Linlin , Chen Peijun , Du Jinqiao
Published: November 2020

This paper presents a new rotor profile of roots vacuum pump composed of arc, involute and cycloid.It’ s whole tooth profile which is described exactly by combining the meshing principle of gears with parameter equation. The performance of meshing of two rotors is improved without profile interference and packet gas, which are the problems of conventional involute profiles. The work provides new theoretical basis for digital design of new rotor profile, its meshing analysis, dynamic emulation, kinematics and dynamics analysis.
Coupling Analysis of Temperature Field and Stress Field of Laser Cladding Die Steel
Authors: Yao Shihang , Zhao Changlong , Liu Jun , Wang Xuxu , Lv Qiyin , Wang Kuo
Published: November 2020

A 3D parametric model was established for the die steel whose matrix material was H13. Ni60 alloy powder was used to cladding the matrix, and a single-layer multichannel finite element model of heat-force coupled laser was established. The laser power P=600W, scan rate v=20mm/s, laser spot radius R=1mm were selected as simulation parameters. The temperature field and stress field in the process of laser cladding are analyzed by finite element method.
Demand Forecast of Restoring Air Material of Helicopter Based on NHPP and Weibull Model
Authors: Niu Penghui , Wang Zhen , Liu Suyong , Jia Ke
Published: November 2020

The demand forecast of spare parts for helicopter air material is one of the key links in the supply and guarantee of helicopter air material. In order to forecast the demand of helicopter restoring air material effectively, a method based on NHPP (non-homogeneous Poisson process) and Weibull model is proposed in this paper. In this method, the reparability of air material is fully considered, and the repaired air materials are divided into two categories: basically repairable and completely repairable. Then, reliability assessment is carried out based on NHPP and Weibull model, and the demand of spare parts for air material is predicted on this basis. The effectiveness is proved by an example.
Effects of deep cryogenic treatment on the microstructure and friction performance of M35 high-speed steel
Authors: Liao Jingwen , Li Liejun , Peng Jihua , Gao Jixiang
Published: November 2020

The tempered M35 samples were deep-cryogenically treated (DCT) at temperature - 240°C for a long time. The microstructure and hardness were characterized by SEM, and Rockwell together with Vicker’s indenter respectively. The wear resistance was tested by a ball-on-disc friction and wear testing against Si3N4 balls. Comparing to high-speed steel without further treatment, the size of grains was reduced to 9.94 μm and promoted the formation of carbides after DCT. However, it was found that the hardness of the samples before and after DCT kept almost the same. Under high load, the wear resistance was slightly improved. This was probably responsible for carbides precipitation and Co precipitated from the α-Fe matrix during DCT.
Effect of sintering temperature and solution treatment on microstructure and mechanical properties of high-N Ni-free austenitic stainless steel prepared by metal injection molding
Authors: Huang Chengcheng , Li Liejun , Ngai Tungwai , Zhang Weipeng , Ngai Sieglind
Published: November 2020

High-N austenitic stainless steel was prepared by injection molding and sintering under nitrogen atmosphere by using gas atomized Cr-Mn-Mo-N duplex stainless steel powders. The powders and binder were mixed, injected, debinded and sintered. Effect of sintering temperature and solution treatment on microstructure and mechanical properties were studied. It shows that sintering temperature has significant effect on N content and density. With the increase of sintering temperature, the sample density was increased, but the N content was decreased. Samples sintered at 1200 °C was composed of austenite and Cr2N, while only austenite can be detected by XRD for samples sintered at 1250 and 1300 °C. The fracture mode of the samples sintered at 1200 and 1250 °C is brittle fracture, along the 45° direction and stress axis, but samples sintered at 1300 °C did not fractured at the maximum load (21 kN) and showed ductility during compression. After solution treatment, the Cr2N was disappeared and samples sintered at 1250 °C did not fractured during compression.
Ultra-fast luminescence of nano-gold film structure
Authors: Shen Fang , Zhou Guyu
Published: November 2020

The Fermi level of gold is not in the band gap, but in the sp band. Therefore, macroscopic gold is usually a non-luminescent material. Unlike gold bulk materials, frequency down-conversion photoluminescence and enhanced photoluminescence from gold nanoparticles have been studied, and the intensity of their photoluminescence is affected by the size, shape and plasmon resonance of the gold nanoparticles. In particular, plasmon resonance helps to increase the photoluminescence intensity by several times than the intensity in the macroscopic gold structure. Gold nanoparticles can also produce photoluminescence including second harmonic and third harmonic under intense photo excitation. Here, in order to study the luminescence properties of gold nanostructures under femtosecond laser, we applied a 5 nm gold film on a Si3N4 substrate by magnetron sputtering. The nano-gold film was excited using a femtosecond laser with an incident peak power density of 2.3 × 109 W/cm2 and 4.5 × 109 W/cm2. We explained that by studying the excitation spectra of nano-gold structures, we can see that SHG occurs at high power density and frequency shift occurs.
Structural Design and Impact Simulation of Glass Fiber Fragile Cover of Rocket
Authors: Huifang Wang , Chenying Zhou , Changfang Zhao , Jie Ren , Jianlin Zhong
Published: November 2020

The fragile cover of rocket not only has the characteristics of sealing and high-temperature resistance, but also can break according to preset scratches when hited by the rocket’s head. In this paper, a penetrating glass fiber fragile cover with scratches is designed, and six structural types are set up with the number of layers laid by glass fiber as independent variables. Based on Hashin failure criterion and damage evolution law, the finite element method is used to simulate the process of rocket breaking through fragile cover and gas flow impinging fragile cover. The results show that the fragile cover will break along the preset scratches, which does not produce debris to interfere with rocket launch. As the number of glass fiber cloth layers increases, the Mises stress of the rocket’s head increased when the fragile cover broken. The impact of the gas flow on the fragile cover of the adjacent pipe is not uniformly distributed, and the maximum value of the Mises stress appears at the scratches of the cover body. As the number of glass layers decreases, the failure index value of the fragile cover under the impact of gas flow increases. The research provides a reference for the design of rocket glass fiber fragile cover.