bluuebunny/crossref_metadata_2025 huggingface dataset:
Stable Intrinsic Long Range Antiferromagnetic Coupling in Dilutely V Doped Chalcopyrite*
Authors: Gong Weiyi , Leung Ching-Him , Sin Chuen-Keung , Zhang Jingzhao , Zhang Xiaodong , Xi Bin , Zhu Junyi
Published: February 2020

A stable and long-range antiferromagnetic (AFM) coupling without charge carrier mediators has been searched for a long time, but the existence of this kind of coupling is still lacking. Based on first principle calculations, we systematically study carrier free long-range AFM coupling in four transition metal chalcopyrite systems: ABTe2 (A = Cu or Ag, B = Ga or In) in the dilute doping case. The AFM coupling is mainly due to the p–d coupling and electron redistribution along the interacting chains. The relatively small energy difference between p and d orbitals, as well as between dopants and atoms in the middle of the chain can enhance the stability of long-range AFM configurations. A multi-band Hubbard model is proposed to provide fundamental understanding of long-range AFM coupling.
Tissue evolution: mechanical interplay of adhesion, pressure, and heterogeneity
Authors: Büscher Tobias , Ganai Nirmalendu , Gompper Gerhard , Elgeti Jens
Published: February 2020

The evolution of various competing cell types in tissues, and the resulting persistent tissue population, is studied numerically and analytically in a particle-based model of active tissues. Mutations change the properties of cells in various ways, including their mechanical properties. Each mutation results in an advantage or disadvantage to grow in the competition between different cell types. While changes in signaling processes and biochemistry play an important role, we focus on changes in the mechanical properties by studying the result of variation of growth force and adhesive cross-interactions between cell types. For independent mutations of growth force and adhesion strength, the tissue evolves towards cell types with high growth force and low internal adhesion strength, as both increase the homeostatic pressure. Motivated by biological evidence, we postulate a coupling between both parameters, such that an increased growth force comes at the cost of a higher internal adhesion strength or vice versa. This tradeoff controls the evolution of the tissue, ranging from unidirectional evolution to very heterogeneous and dynamic populations. The special case of two competing cell types reveals three distinct parameter regimes: two in which one cell type outcompetes the other, and one in which both cell types coexist in a highly mixed state. Interestingly, a single mutated cell alone suffices to reach the mixed state, while a finite mutation rate affects the results only weakly. Finally, the coupling between changes in growth force and adhesion strength reveals a mechanical explanation for the evolution towards intra-tumor heterogeneity, in which multiple species coexist even under a constant evolutionary pressure.
Domestic groundwater abstraction in Lagos, Nigeria: a disjuncture in the science-policy-practice interface?
Authors: Healy A , Upton K , Capstick S , Bristow G , Tijani M , MacDonald A , Goni I , Bukar Y , Whitmarsh L , Theis S , Danert K , Allan S
Published: February 2020

The rapid development of groundwater systems as part of urban water supplies around the globe is raising critical questions regarding the sustainable management of this essential resource. Yet, in many major cities, the absence of an effective policy regime means that the practice of groundwater exploitation is driven by the actions of domestic households and drilling contractors. Understanding what shapes the decisions and practices of these actors, their understandings of the groundwater resource and the extent to which scientific knowledge shapes this understanding, is an area of critical importance that is currently under-researched. Using a mixed-methods methodology, the paper explores domestic practices of groundwater abstraction in Lagos, Nigeria. It finds that there is a disjuncture between the households who are actively shaping exploitation of the groundwater resource on a day-to-day basis and science and state actors. This disjuncture results in household decisions that are influenced by commonly held, but potentially outdated, perceptions of the groundwater resource rather than scientific evidence or policy instruments. The unseen nature of groundwater resources effectively renders the scale of changing groundwater conditions invisible to households and the state, adding to the challenge of influencing practice. Addressing this disjuncture requires not just more scientific knowledge, but also the active construction of interfaces with, and between, non-state actors through which knowledge can be confronted, discussed and shared.
A predictive model for seasonal pond counts in the United States Prairie Pothole Region using large-scale climate connections
Authors: Abel Benjamin D , Rajagopalan Balaji , Ray Andrea J
Published: February 2020

The Prairie Pothole Region (PPR), located in central North America, is an important region hydrologically and ecologically. Millions of wetlands, many containing ponds, are located here, and they serve as habitats for various biota and breeding grounds for waterfowl. They also provide carbon sequestration, sediment and nutrient attenuation, and floodwater storage. Land modification and climate change are threatening the PPR, and water and wildlife managers face important conservation decisions due to these threats. We developed predictive, multisite forecasting models using canonical correlation analysis (CCA) for pond counts in the southeast PPR, the portion located within the United States, to aid in these important decisions. These forecast models predict spring (May) and summer (July) pond counts for each region (stratum) of the United States Fish and Wildlife Service’s pond and waterfowl surveys using a suite of antecedent, large-scale climate variables and indices including 500 millibar heights, sea surface temperatures (SSTs), and Palmer Drought Severity Index (PDSI). Models were developed to issue forecasts at the start of all preceding months beginning on March 1st. The models were evaluated for their performance in a predictive mode by leave-one-out cross-validation. The models exhibited good performance (R values above 0.6 for May forecasts and 0.4 for July forecasts), with performance increasing as lead time decreased. This simple and versatile modeling approach offers a robust tool for efficient management and sustainability of ecology and natural resources. It demonstrates the ability to use large-scale climate variables to predict a local variable in a skilful way and could serve as an example to develop similar models for use in management and conservation decisions in other regions and sectors of the environment.
Impacts of ENSO and Madden–Julian oscillation on the genesis of tropical cyclones simulated by general circulation models and compared to observations
Authors: Shin Jihoon , Park Sungsu
Published: February 2020

Using the Seoul National University Earth System Model Version 0 (SEM0) and Community Earth System Model version 1 (CESM1), we analyzed the impacts of El Niño-Southern oscillation (ENSO) and Madden–Julian oscillation (MJO) on the genesis of tropical cyclones (TG). SEM0 is known to simulate ENSO, MJO, and TG reasonably well, all of which are difficult to simulate with general circulation models (GCMs). Observational analysis revealed that both ENSO and MJO have substantial impacts on global TG and that the impact of ENSO (MJO) on regional TG varies in a complex manner depending on the phase of MJO (ENSO). Both GCMs underestimate the observed TG over the North Atlantic and have relatively poor performance for simulating the TG anomalies associated with ENSO compared to simulating those associated with MJO. Overall, SEM0 shows much better performance than CESM1 in terms of reproducing the observed impacts of MJO and combined impacts of ENSO and MJO on TG. Therefore, SEM0 can serve as a useful tool for studying the interactions among them to improve the forecasting of tropical cyclones.
The Green Building Development Status in Guangzhou
Authors: Junfei He , Jiayu Huang , Zeqiong Xie , Zhenqian Xiao , Chao Feng
Published: February 2020

The paper mainly introduces the green building development status in Guangzhou. As one of the well developing areas of green building in China, Guangzhou’s green building projects are gradually increasing. However, the development is still in its infancy. There are certain problems and limitations of the green building development.
A Case Study on Energy Audit of the Public Institution
Authors: Jiayu Huang , Junfei He , Zeqiong Xie , Zhenqian Xiao , Chao Feng
Published: February 2020

In 2016, China issued the “Interim Measures for the Administration of Energy Auditing of Public Institutions”. Energy audits of public institutions have received increasing attention and have been widely used. Through the energy audit, a public institution found that the energy management, the energy measurement and the energy statistics system have not been perfected. The transformer load rate is low. Moreover, there are high energy consumption and backward equipment existed. Therefore, the energy conservation proposals are put forward.
An AGC dynamic control method based on DQN algorithm
Authors: Jianjun Su , Changhui Ma , Shan Li , Xiaoyu Li , Bing Zhang , Wenxue Liu
Published: February 2020

In order to cope with the incompatibility of traditional AGC control under CPS control performance standard, this paper proposes a hierarchical control framework based on DQN algorithm. It effectively solves the problem of dimensionality disaster of Q learning by using neural network instead of state action pair, and speed up the convergence. Through simulation verification, this method can effectively improve the system CPS control performance index and effectively reduce the system power generation cost.
Analysis of Noise Characteristics in Microseismic Monitoring
Authors: Liu Liting , Kang Liang , Zhang Xi , Tang Yong , Li Zilong
Published: February 2020

The effective signal energy of microseismic data is weak, and the received data will contain a lot of noise because of its special source excitation mode. At the same time, because the wave will inevitably lose energy in the process of propagation, the signal on the section is weak amplitude, weak continuity, even the effective signal on the whole line is submerged by noise, and the signal-to-noise ratio of the data is very low. In this paper, the common noise in different monitoring methods is analyzed, and the common processing methods in production are summarized.
Spectrophotometric Determination of Tiopronin using 2,2’-Bipyridyl as Chromogenic Reagent
Authors: Tu Changqing , Wen Xinrong
Published: February 2020

The hydrosulfuryl(-SH) in tiopronin molecule has reducibility, and it can reduce Fe3+ to Fe2+. We use 2,2’-bipyridyl as chromogenic reagent of Fe2+, Fe2+ react with 2,2’-bipyridyl to form the orange red complex which the maximum absorption is at 522 nm. By measuring the absorbance of the orange red complex, the content of tiopronin can be determinated. A new method for the spectrophotometric determination of tiopronin has been established. The content of tiopronin is determinated using this method, and the results are satisfactory.
The Design of Car Head-up Display System
Authors: Ying Min
Published: February 2020

In order to meet the requirements of driving safety and provide consumers with safer travel, this paper designs a car head-up display system. The system consists of two parts: circuit system and optical system. The circuit system is connected to the car through CANBus interface to realize data communication. Through the circuit system, the data of car driving can be obtained, and then the data can be displayed in front of the driver through the optical system, so that we can know the speed of driving, navigation and other related data without lowering our head. The test results show that the circuit system and optical system can run normally and steadily.
Preparation of a gel-type microbial-missile for biodegradation of oil pollution
Authors: Shi Jianqiang , Zhang Shaojun , Wang Mingyu
Published: February 2020

The removal of oil spill pollution is a global problem. In order to solve the problem of low biodegradation efficiency, a series of microbial-missile materials with high floatability, hydrophobicity and biological affinity were prepared to enhance the degradation of oil spill. Hydrophobic macroporous materials with polar groups inside and hydrophobic aliphatic polyester outside were prepared by physical and chemical methods using SA/PVA as substrate for gel-type microbial-missile. The experimental results show that the saturated adsorption rate of macroporous gel-type microbial-missile to oil particles is as high as 18.17 g/g, the contact angle is 149.300°, the average density is 0.5883 g/cm3, the average mechanical strength is 2.52 mN, the penetration rate of 40 s is 82.72%, and the degradation rate of crude oil in 7 days is 88.95%.
The research of relative permeability curve for microbial flooding in Baolige oilfield
Authors: Liu Shasha , Fu Yaxiu , Gu Yi , Wang Rui , Wang Guan , Duan Lisha , Guo Suzhen , Wei Lili
Published: February 2020

To adequately simulate environment of Baolige oilfield reservoir, research the seepage variation of microbial in the reservoir, we selected the current microbial flooding system, nature core, dehydration crude oil and injection water of Baolige oilfield. And the evaluation experiments of microbial flooding system and the relative permeability experiments of water flooding and microbial flooding were carried out. Results showed that the flooding system had obvious effect to reduce the emulsification, viscosity and IFT. Comparing to the water flooding, the two-phase seepage area expanded, oil phase permeability endpoint shifted to the right, and residual oil saturation decreased when using microbial flooding. The water phase permeability decreased and the oil phase permeability increased. The relative permeability in the isotonic point changed little, but shifted to the right. Microbial flooding anhydrous recovery period was longer, and the anhydrous recovery rate was higher. In the condition of the same injection, microbial flooding had higher degree of reserve recovery and the displacement pressure was lower. The experiment results fully reflected the two-phase flow in the microbial flooding process, and provided important parameters and basic basis for the prediction and effect evaluation of microbial flooding.
Preparation of Biodiesel Based on Alkaline Ionic Liquid [Bmim]OH Catalyzed Castor Oil
Authors: Zhang Aihua , Wang Qin , He Yidan , Lai Pengying , Miu Yifu , Xiao Zhihong
Published: February 2020

In this experiment, a new basic ionic liquid [Bmim]OH was synthesized from 1-methylimidazole and sodium hydroxide, which was used to catalyze the preparation of biodiesel from castor oil. The catalyst of [Bmim]OH was compared with KOH and tetrabutylammonium hydroxide during the study. The experimental results showed that the latter two were better than the latter two. The orthogonal experimental design scheme was used to optimize the process conditions. The optimized catalytic conditions of alkaline ionic liquid [Bmim]OH were as follows: the catalyst dosage was 1%, the molar ratio of alcohol to oil was 6:1, the reaction temperature was 40 °C, and the reaction time was 60min. Under the optimized conditions, the crude methyl ester mixture yield is higher than 97%, the castor oil is more than 95% converted to the product methyl ester, and the catalyst of [Bmim]OH is used for six times without significant consumption, and the catalytic performance is stable.
Removal of Oil from SZ36-1 Simulated Oil Sands Using Sophorolipid Biosurfactant
Authors: Wang Junqi , Wang Juan , Dong Sihao , Li Guobin , Kong Xiangping
Published: February 2020

The sophorolipid biosurfactant was used to remove the oil from the SZ36-1 simulated oil sands. The effects of the sophorolipid concentration, the mass ratio of sophorolipid solution to oil sands (liquid/solid ratio), and the extraction time on the oil extraction efficiency were investigated. Based on the single-factor tests, the optimum results were obtained under the conditions of sophorolipid solution concentration to be 100 mg·L−1, the liquid/solid ratio to be 50:1 and the extraction time to be 2 h. The corresponding oil extraction rate from oil sands reached up to 42%, which was comparable to the result from 2.5 g·L−1 chemical surfactant of sodium dodecyl sulfate (the value of 2.5 g·L−1 was higher than its critical micelle concentration). The oil extraction rate of crude oil with sophorolipid solution was almost not affected by the existence of sodium chloride. The sophorolipid biosurfactant has high surface activity and good oil removing capacity, and is expected to replace the synthetic surfactants to be used in petroleum exploitation and crude oil pollution treatment.
Study on diffusion of NaOH solution in zinc-rich epoxy coating using EIS
Authors: Yang Chao , Zili Li
Published: February 2020

In order to explore the diffusion process of NaOH solution in zinc-rich epoxy coating, in this paper, conventional three-electrode system was used to test the open circuit potential and electrochemical impedance spectrum, and equivalent electric circuit was fitted to get the related parameters including capacitance, resistance, phase angle and et al to reveal the diffusion process. The results show that three stages are divided including diffusion in coating, finite layer diffusion and double layer diffusion, and two criterions are put forward.
The research progress on micro-arc oxidation of aluminum alloy
Authors: Yuting Dong , Zhiyang Liu , Guofeng Ma
Published: February 2020

The micro-arc oxidation of aluminum alloy is a kind of surface treatment technology for in-situ growth of a hard ceramic film with Al2O3 as the main effect of instantaneous high temperature and high pressure generated by arc discharge on the surface of aluminum alloy. This technology can significantly improve the wear resistance, corrosion resistance, hardness and other properties of the aluminum alloy matrix. This paper introduces the characteristics, influencing factors, research status of domestic and foreign micro-arc oxidation technology, and prospects for future research directions.
The establishment of a newly modified numerical global springback compensation method
Authors: Xiong Wei , Zhang Wenfeng , Lv Yong , Chuan Li , Song Xiaohui , Xia Yushan
Published: February 2020

Part shape deviation caused by spring back is a quality problem in sheet metal forming. There are two major approaches, adjusting tooling shapes and adopting process control. This paper focused on tooling contour design. A new die design approach, called global compensation method (GC), has been proposed and it possesses following advantages. Compensation factor in displacement adjustment method (DA) is extended to a compensation matrix, thus every node has its own compensation magnitude and compensation direction, which are related to the global forming error.
Prediction of Miscibility of HTPB Curing System and Solvents by Molecular Dynamics Simulations
Authors: Bo Liu , Xiaoyu Bu , Lin Wang
Published: February 2020

In order to study on HTPB curing system and solvent’s miscibility, molecular dynamic simulations were performed to analyse curing system’s miscibility with water, ethyl alcohol, methylbenzene, acetone and tetrahydrofuran from several aspects like solubility parameter, molecular configuration and density distribution. The result shows that the computed results of the solubility parameter have high consistency with experimental values and the maximum relative error is less than 3%. The solubility parameter differences of acetone, tetrahydrofuran and curing system are relatively small with a homogeneous distribution and a relatively high miscibility. Methylbenzene’s miscibility is general while the ethyl alcohol’s and water’s miscibility are relatively poor.
Optimization and control of NOx in coke oven vertical flue under flue gas recirculation
Authors: Wang Guanghua , Wang Guocheng , Wang Qingdong , Yan Zihao
Published: February 2020

The orthogonal experimental design with CFD simulation was carried out to simulate combustion in the coke oven vertical flue at external flue gas recirculation. The control of nitrogen oxides (NOx) generation was analysed by different factors such as air excess coefficient, oxidant preheating temperature, flue gas recirculation and oxidizer inlet cross-sectional area ratio. The simulation results showed that the the orthogonal experimental design with CFD had a significant effect on the combustion process. The flue gas recirculation ratio effectively improved the temperature distribution uniformity in the vertical flue, and had a significant effect on NOx production in the vertical flue. Within the parameters of the orthogonal design, when the air excess coefficient was 1.1, the oxidant preheating temperature was 1200 K, the flue gas recirculation ratio was 30%, and the oxidant inlet cross-sectional area ratio was 0.5, the NOx production in the coke oven vertical flue was the smallest, lower than the industry emission standard.
Dry surface modification of heavy calcium carbonate powder with two modifiers
Authors: Li Min , Yang Xiaohong , Chen Jianbing
Published: February 2020

In this work, The modification of heavy calcium carbonate powder was studied by dry surface modification with stearic acid and anhydrous citric acid. we have developed a facile and inexpensive dry surface method to fabricate a lower oil absorption value of calcium carbonate surface. The modification process was analyzed by modifying temperature, modifying time, modifiers percentage. Infrared spectral and TG showed that stearic acid modifier was mainly reducing oil absorption value of CaCO3 powder from 33.9 ml/100 g to 19.0 ml/100 g.
Preparation of porous composite materials with semi-coke based activated carbon doped with graphene oxide
Authors: Yang Zhiyuan , Ning Hai Long , Jia Hong , Li Yinyan , Meng Zhuoyue , Chen Zhiping
Published: February 2020

In this paper, the waste semi-coke is used as the carbon precursor, doped with a certain amount of graphene oxide (GO), and activated by KOH to obtain graphene-doped activated carbon. The changes of morphology and structure were compared by SEM, the properties of specific surface area and pore structure were tested by nitrogen adsorption at low temperature, and the changes of iodine adsorption capacity of samples with different ratio were tested. Finally, the graphene-doped activated carbon with specific surface area of 1072.08 m2/g and iodine adsorption capacity of 1223.99 mg/g was obtained. The optimal ratio of semi-coke to graphene oxide was 300:1, KOH and the semi-coke ratio is 4:1, which provides an excellent adsorbent for the adsorption of methane and carbon dioxide.
Synthesis of triple-doped core/shell/shell upconversion nanoparticles
Authors: Fu Ying , Du Yuanyuan , Hu Qixing , Gao Xing , He Wen , Li Zhihua
Published: February 2020

A novel triple-doped core/shell/shell NaGdF4/NaGdF4:Yb, Tm,Nd/NaGdF4 upconversion nanoparticles(UCNPs) has been designed and synthesized by thermal decomposition. Yb3+ and Nd3+ were used as sensitizers and Tm3+ with multi-level was activators. Three-layout nanoparticles exhibits 1.5 times strong emission than two-layout structure. The UC spectrum exhibits two bands centered at 525–535 and 578–585 nm from Nd3+, corresponding to 4G7/2–4I9/2 and 4G7/2–4I11/2 transitions after excitation at 800 nm. These nanocrystals are promising an attractive luminescent biomarkers for biological and magnetic resonance imaging.
Preparation and Drug Release Properties of Fe3O4/Chitosan Magnetic Microspheres
Authors: Li Mingming , Zhang Xuyan , Zhan Shiping , Hou Weimin
Published: February 2020

Fe3O4/chitosan(CS) magnetic microspheres were prepared by emulsion crosslinking method, in which 5-fluorouracil (5-Fu) was loaded as model drug. The preparation conditions were optimized by orthogonal experiment with the the package rate as an index. The structure and morphology of the magnetic microspheres were characterized by scanning electron microscopy(SEM). The drug release properties of the microspheres in vitro were investigated. The optimal preparation conditions of drug loaded magnetic microspheres were as follows: 0.3 g 5-Fu, 5 mL glutaraldehyde, 3 h crosslinking time and 0.2 g/ml acetic acid concentration. Under these conditions, the drug loading efficiency was up to 6.35% as well as the package rate was up to 35.2%. The Fe3O4/chitosan magnetic microspheres also displayed an excellent drug release behavior under the experimental conditions of simulated intestinal fluid. The releasing content reached a peak in 10 h.
Study on chemical looping reforming reaction of methane based on PSO-BP neural network
Authors: Liu Yongbin , Ma Xiaoxun , Xu Long
Published: February 2020

Through the study of methane chemical looping reforming reaction, the BP neural network model optimized by the PSO algorithm was established, and the network structure of the PSO-BP model was determined to be 9-11-3. After training the model, the mean square error of the network was finally stabilized at 0.013509, and the learning rate was finally fixed at 0.083453, while the fitting degree of the training sample and the test sample were both above 0.979, indicating that the network of the PSO-BP model had strong learning ability and generalization capability, and was a simulation prediction model with good performance. The PSO-BP model was used to simulate the full set of experimental condition data, and the most experimental condition was the cerium iron composite oxygen carrier prepared by co-precipitation method (No.2) with a molar ratio of 0.7/0.3, a calcination temperature of 800 °C, a calcination time of 6h, a reaction temperature of 850 °C, a reaction time of 13min, and a circulation number of 0, while it was consistent with the actual experimental.
Ceo2 promoted the performance of Ni/Al2O3 catalyst for CRM reaction
Authors: Lv Penggang , Ma Xiaoxun , Xu Long
Published: February 2020

The promoted effect of CeO2 on the reaction of Ni/Al2O3 catalyst in the syngas of CO2 reforming of methane (CRM) was studied. The results showed that the catalyst prepared with CeO2 addition exhibited high activity and stability, and the conversions of CH4 and CO2 could reach 96% at 800 °C when the amount of Ce was 5 wt%. SEM, H2-TPR, CH4-TPSR and CO2/O2-TPO characterization indicated that addition CeO2 could enhance the interaction between support and Ni species in preparation process, enabling the capacity of catalyst to resist carbon deposition and metal sintering.
Efficient synthesis of γ-valerolactone from ethyl levulinate over Ni/V2O5
Authors: Cao Xi , Dong Heda , Chen Han , Xu Qiong , Yin Dulin
Published: February 2020

γ-valerolactone (GVL) has been recognized as one of the most value-added chemicals derived from biomass. In this work, an efficient Ni/V2O5 catalyst was prepared via solid phase grinding and in-situ reduction. The Ni/V2O5 catalyst was employed for catalytic transfer hydrogenation (CTH) of ethyl levulinate (EL) to GVL using 2-propanol as a hydrogen source. An excellent GVL selectivity of 93.04 % at EL conversion of 97.40 % could be achieved at 180 °C in 4 h using 30% Ni/V2O5 as the catalyst. This catalyst was able to be reused for five times with the GVL selectivity decreased a little. A possible adsorption mechanism of generate active H species in CTH of EL over Ni/V2O5 was proposed.
Free vibrations of cylindrical laminated shells – introduction to optimal design in divergence and flutter problems
Authors: Muc A. , Augustyn M.
Published: February 2020

Aeroelastic properties, such as free vibrations of multilayered composite cylindrical shells, are investigated in the present paper. It is well known that the eigenmode (eigenvalue) analysis is a crucial point in the estimations/calculations of the divergence and flutter speeds characterizng dynamic instability. In this study the maximization problem of eigenfrequencies and eigenmodes is discussed, especially from the point of view of stacking sequences of composite panels. A special attention is focused on two types of the shell wall construction: a) angle-ply ±θ and b) symmetrical discrete laminates built of layers oriented at 0°. ±45° 90°. The analytical formulae is derived with the use of the Rayleigh-Ritz method for simply supported cylinders. It allows us to solve the optimum problem easily for angle-ply fibre orientations. For symmetrical laminates with discrete fibre orientations the optimal solutions are searched for using finite element analysis combined with genetic or evolutionary algorithms. The influence of geometrical parameters describing the cylindrical panel is also demonstrated herein.
The Influence of Diameter-to-thickness Ratios on the Response and Failure for Locally-dented Circular Tubes Submitted to Cyclic Bending
Authors: Lee K. L. , Weng M. L. , Pan W. F.
Published: February 2020

This paper describes the cyclic bending response and failure of 6061-T6 aluminum alloy locally-dented tubes (abbreviation: 6061-T6 LDT) with different diameter-to-thickness ratios (abbreviation: D
o/t ratio) of 16.5, 31.0 and 60.0. A small lateral local dent was created on the tube using a simple technique. A tube having a dent depth from very shallow to about 2.4 times the thickness of the tube wall is considered. From the first bending cycle, the moment-curvature relationship depicts a closed and stable loop. Due to small and localized dents, dent depth shows very small influence on its relationship. But, as the number of bending cycle increases, the ovalization-curvature relationship shows an increase and a ratchet-like distribution. However, the dent depth shows a dramatic effect to this relationship. Furthermore, for a certain D
o/t ratio, five non-paralleled straight lines of five different dent depths were found for the controlled curvature-number of cycles required to ignite failure relationship on a log-log scale. Finally, an empirical formula was introduced to describe the aforementioned relationship. As a result, the experimental and analytical data were found to agree well.
Absorptive protective padding with electrospinned polyester fibers with hydrogel matrix
Authors: Soh C. B. , Lee X. H. , Lim Samuel W. Y. , Sipalah N. F. B. , Ho Paul
Published: February 2020

Hip fractures has been prevalent especially among aged elderly. This can lead to permanent disability of the elderly as they are wheel-chaired bound after suffering from hip fractures. In this work, we explore the design of a protective hip pad which encapsulate the hydrogel and fibres composite in a laminated sheet. The hydrogel was fabricated using Polyvinyl alcohol (PVA) with distilled water. Two types of electrospinned fibres, Nylon-6 fibres and polyester fibres were used as filler. The fabrication of hydrogel matrix composite was varied by the weight percent of nylon 6,6 pellets dissolving in formic acid as compared to Hydrolysed Poly(Vinyl alcohol) to form crosslinked PVA with water. The impact absorption concept was to allow the gel-like hydrogel to flow through the fibres pores and during this process, part of the energy would be dissipated in the matrix composite. This lower the impact force being transferred to the user’s hip and prevent the facture of the elderly’s hips during fall. The protective padding with 20 layers of polyester fibres with 2.5wt % of PVA had the lowest impact force of 0.8 kN as compared to conventional protective padding with measured 1.07kN impact force for impact study.
Design of Joint Test Device for Fuel Delivery Shut-off Valve
Authors: Kong Guangming , Zhu Lonxiang , Zou Gang , Wang Zhanyong , Zhang Ding , Yu Dehui
Published: February 2020

In view of the fact that the new aircraft units were used, it was common to lack the fuel accessory inspection equipment, a set of combined test equipment for fueling and fuel delivery shut-off valve was designed. The basic work of the fuel delivery shut-off valve was introduced, the composition and principle of fueling test system and electric control system were described, and the realization methods of the hardware and software were given. The practical application shows that the test equipment can meet the test requirements of this type of fuel accessories, fully meeting the design goals.
Study on Activation of Waste Clay Brick Powder
Authors: Changwei Xu , Xutong Yang
Published: February 2020

Recycling and recycling of construction waste is a hot research topic nowadays. In this paper, clay bricks in building waste are activated by physical method (grinding) and chemical method (alkali activation). The effects of fineness after grinding time, types and dosage of activator on the activity of waste brick powder are studied. The results show that with the increase of grinding time, the specific surface area of waste brick powder increases, and the activity coefficient of waste brick powder increases. When grinding time is 90 minutes, the activity index reaches 67%. When the specific surface area of waste brick powder is 467 m2/kg, the activity index of waste brick powder increases first and then decreases with the increase of calcium hydroxide content. When calcium sulfate dihydrate is added alone, the activity index of waste brick powder increases first and then decreases with the increase of calcium sulfate dihydrate content. When calcium hydroxide and calcium sulfate dihydrate are mixed together, the increase of activity index is better than that of calcium hydroxide and calcium sulfate dihydrate alone. The 4% calcium hydroxide + 3% calcium sulfate dihydrate composite system has the best activation effect on brick powder.
Synthesis and Photocatalytic Activity of Submicron Strontium Titanate in Soluble Polymer System
Authors: Dong Yingnan , Zhao Yan , Tang Jian , Bi Xiaoguo
Published: February 2020

Recently, micro-nano-strontium titanate photocatalytic materials have been one of the research hotspots because they can degrade organic pollutants. In the work, 200-400 nm strontium titanate powder was synthesized by soluble polymer (PEG) system and low-temperature direct precipitation method. Studies showed that the concentration of PEG and the degree of polymerization had a significant effect on the particle size of the powder. At the same time, the work studied the photocatalytic properties of the obtained strontium titanate powder, discussing the effect of particle size of strontium titanate on its photocatalytic activity.
Study on Mechanical Properties of Wall Panel with Insulation Decoration Structure
Authors: Zhang Jusong , Li Wangqiang , Yang Zhenyu
Published: February 2020

In order to explore the safety performance of the wall panel with insulation decoration structure in the actual application, some test were made. The test results of this paper show that: The rock wool with a density of 120 kg/m3 and the polyurethane with a bonding density of 50 kg/m3 are selected as the core material for the temperature retention, whose average tensile strength can reach 139.33 KPa; The mean value of single point anchoring force of 12 mm thick ceramic plate and back bolt as decorative surface is 2088.29 N, and the mean value of the structural adhesive strength between the ceramic plate and keel is 3092.07 KPa; When the uniformly distributed load on the wallboard reaches 6.53 KPa, its deflection reaches 1/180 of itself.
Nonlinear algorithms of residual stresses reconstruction for axisymmetric problem
Authors: Chen Donghai , Tian Quan , Zhang Xun , Yun Juntong
Published: February 2020

A non-destructive testing method for three-dimensional stress of a glass cylinder based on photoelasticity is presented. Based on simulated stresses in the glass cylinder, intensity images output from a circular polariscope are calculated by Jones calculus. Therefore, the isoclinic angle and optical retardation can be simulated. Then the residual stresses in the glass cylinder can be reconstructed in cylindrical coordinates. By comparing the reconstructed stresses with numerical simulated stresses, there is good agreement but with some mismatches.
Magnetic graphene oxide as sorbent for SPE of melamine from water
Authors: Xu W , Huang J , Liang M
Published: February 2020

Melamine introduced into environment water through various industrial effluents can pose negative effects on ecosystem, thus it is required to establish suitable analytical methods for detection of melamine in environmental water samples. In this work, magnetic graphene oxide was synthesized and used as the sorbent for solid phase extraction (SPE) of melamine. The parameters that affect the extraction efficiency of melamine were studied. The optimum conditions, including sample pH, extraction and desorption time, and eluent volume were obtained. The analytical performance of the method was evaluated, and it was found that the limit of detection for melamine was 0.15μg/L and the relative standard deviation was 3.6 %. The proposed method was utilized in the detection of melamine in various water samples with recoveries of 92.0-95.8%.
Suppressed antiferromagnetic ordering and enhanced electrical conduction in doped iridate Sr2−xPrxIrO4
Authors: Liu Hui , Liang Dandan , Bian Jian , Feng Yuan , Xie Yu , Fang Baolong
Published: February 2020

Sr2IrO4 has been shown to exhibit a novel J
eff = 1/2 Mott spin–orbit insulating state with antiferromagnetic ordering. In the present investigation, the effects of Pr substitution at Sr-site on structural, magnetic and electrical properties are studied in Sr2IrO4. Pr-doped samples still retain the insulating behavior, but with the increase of Pr doping concentration, the resistivity decreases. The magnetic properties show that long-range antiferromagnetic order is collapsed when the Pr doping content increases up to 20%, which may results from a competition between the AFM (Ir 5d electrons) and ferromagnetic (Pr 4 f electrons) coupling. In addition, Pr doping induces a spin glasslike state at low temperatures.
Morphology and mechanical characterization of carbon nanotubes/epoxy based material filled with hollow glass microsphere
Authors: Imran Mohammed , Rahaman Ariful , Pal Soumen
Published: February 2020

The hollow glass microsphere (HGM)/carbon nanotubes (CNTs)/epoxy composite foam are fabricated by solution casting of functionalized CNT and functionalized HGM-epoxy dispersion. Five weight ratio configurations (2, 4, 6, 8, and 10 wt%) of functionalized–HGMs were considered and compared with 0.1 wt% CNT/epoxy to investigate the effects of hollow micro sphere enrichment. This study investigate the effect of hollow glass microspheres (HGM) on the compressive strength and storage modulus of CNT modified epoxy resin. The results revealed that the incorporation of HGM improved the damping performance evidently and broadened damping temperature range. TEM image of the composite show a better dispersion of CNTs in epoxy matrix. SEM micrographs of composite foams are investigated to determine structure development and CNTs, HGM dispersion, with regard to experimental results, especially compression test.
Evaluation of anticorrosive and self-healing performances of TiO2-added cerium conversion coatings developed on 211Z aluminium alloy
Authors: Zhou Siyin , Mao Jian
Published: February 2020

Titanium dioxide (TiO2) sol was added to the cerium conversion coating (CeCC) for preparing the CeCC-TiO2 composite coating covered on the surface of 211Z aluminium alloy. The anticorrosive and self-healing performances of the composite coatings were further investigated. The result shows the increasing Eg of CeCC-TiO2 could improve the anticorrosive and anti-intergranular corrosion performances of 211Z aluminium alloy under NaCl solution. Because the composite coating with high Eg value can effectively suppress the anodic reactions, provide greater coating resistance, and bring more compact surface structure. The self-healing ability of CeCC could be improved by adding TiO2 sol and the Eg value of the CeCC-TiO2 composite coating with the best self-healing performance is 3.38 eV. The cause of it lies in that the coeffect of the dynamic inhibition of Ce3+ and the inert inhibition of Ce4+ influences the self-healing performance of the composite coatings.
Temperature dependence of Raman scattering in defect-free AlN nanorods grown on multilayer graphene by van der Waals epitaxy
Authors: Xiong Xianjie , Xu Yu , Zheng Shunan , Liu Tong , Su Xujun , Cao Bing , Wang Chinhua , Xu Ke
Published: February 2020

The crystalline quality of traditional epitaxy is hampered by the lattice and thermal mismatch of epilayer and substrate. Van der Waals epitaxy (vdWE) allows the epilayer to show no excessive strain and results in low defects density. Here, the multilayer graphene as a substrate for c-axis-oriented growth of vertically aligned AlN nanorods by vdWE have been presented. Defect-free of the AlN nanorods was evidenced through transmission electron microscopy (TEM). The strain of AlN nanorods was reduced with the exponential of height, which was characterized by micro-Raman spectroscopy. Moreover, the temperature dependence of Raman scattering of AlN has been further studied for clarifying the relationship of optical phonons and temperature. This temperature dependence was well matched by an empirical relationship which has proved to be applicable for other III-Nitride (such as GaN, InN) semiconductors.
MichelaNglo: sculpting protein views on web pages without coding
Authors: Ferla Matteo P , Pagnamenta Alistair T , Damerell David , Taylor Jenny C , Marsden Brian D
Published: February 2020

Motivation

The sharing of macromolecular structural information online by scientists is predominantly performed via 2D static images, since the embedding of interactive 3D structures in webpages is non-trivial. Whilst the technologies to do so exist, they are often only implementable with significant web coding experience.

Results

Michelaɴɢʟo is an accessible and open-source web-based application that supports the generation, customization and sharing of interactive 3D macromolecular visualizations for digital media without requiring programming skills. A PyMOL file, PDB file, PDB identifier code or protein/gene name can be provided to form the basis of visualizations using the NGL JavaScript library. Hyperlinks that control the view can be added to text within the page. Protein-coding variants can be highlighted to support interpretation of their potential functional consequences. The resulting visualizations and text can be customized and shared, as well as embedded within existing websites by following instructions and using a self-contained download. Michelaɴɢʟo allows researchers to move away from static images and instead engage, describe and explain their protein to a wider audience in a more interactive fashion.

Availability and implementation

Michelaɴɢʟo is hosted at michelanglo.sgc.ox.ac.uk. The Python code is freely available at https://github.com/thesgc/MichelaNGLo, along with documentations about its implementation.
Phenotypic divergence, convergence and evolution of Caucasian rock lizards (Darevskia)
Authors: Tarkhnishvili David , Gabelaia Mariam , Adriaens Dominique
Published: February 2020

Phenotypic evolution can cause either divergent or convergent phenotypic patterns. Even adaptation to the same environment may result in divergence of some elements of phenotype, whereas for other morphological traits it could cause phenotypic convergence. We hypothesize that at least some phenotypic characters diverge monotonically, hence they evolve irreversibly even in very closely related species, and this happens in spite of multiple convergent adaptive patterns. We studied the evolution of phenotype in 13 closely related Caucasian rock lizards (Darevskia), whose phylogenetic relationships are well known. We used head shape and the outlines of three important scales, using geometric morphometrics. We studied the association of the overall head shape, individual principal components of head shape and scale outlines with four predictors: phylogeny, habitat, sex and size. The overall head shape was not correlated with any of these predictors, whereas some principal components were correlated with habitat or phylogeny. Habitat type explained the highest fraction of variation in head shape and anal scale area. The relatedness inferred from the components of phenotype not correlated with habitat was congruent with the phylogenetic tree inferred from molecular data. Although adaptation to local environments may obscure the phylogenetic signal present in phenotype, there are components of phenotype whose evolution is irreversible.
Corticospinal-motor neuronal plasticity promotes exercise-mediated recovery in humans with spinal cord injury
Authors: Jo Hang Jin , Perez Monica A
Published: February 2020

Rehabilitative exercise in humans with spinal cord injury aims to engage residual neural networks to improve functional recovery. We hypothesized that exercise combined with non-invasive stimulation targeting spinal synapses further promotes functional recovery. Twenty-five individuals with chronic incomplete cervical, thoracic, and lumbar spinal cord injury were randomly assigned to 10 sessions of exercise combined with paired corticospinal-motor neuronal stimulation (PCMS) or sham-PCMS. In an additional experiment, we tested the effect of PCMS without exercise in 13 individuals with spinal cord injury with similar characteristics. During PCMS, 180 pairs of stimuli were timed to have corticospinal volleys evoked by transcranial magnetic stimulation over the primary motor cortex arrive at corticospinal-motor neuronal synapses of upper- or lower-limb muscles (depending on the injury level), 1–2 ms before antidromic potentials were elicited in motor neurons by electrical stimulation of a peripheral nerve. Participants exercised for 45 min after all protocols. We found that the time to complete subcomponents of the Graded and Redefined Assessment of Strength, Sensibility and Prehension (GRASSP) and the 10-m walk test decreased on average by 20% after all protocols. However, the amplitude of corticospinal responses elicited by transcranial magnetic stimulation and the magnitude of maximal voluntary contractions in targeted muscles increased on overage by 40–50% after PCMS combined or not with exercise but not after sham-PCMS combined with exercise. Notably, behavioural and physiological effects were preserved 6 months after the intervention in the group receiving exercise with PCMS but not in the group receiving exercise combined with sham-PCMS, suggesting that the stimulation contributed to preserve exercise gains. Our findings indicate that targeted non-invasive stimulation of spinal synapses might represent an effective strategy to facilitate exercise-mediated recovery in humans with different degrees of paralysis and levels of spinal cord injury.
Clinical and Laboratory Standards Institute and European Committee on Antimicrobial Susceptibility Testing Position Statements on Polymyxin B and Colistin Clinical Breakpoints
Authors: Satlin Michael J , Lewis James S , Weinstein Melvin P , Patel Jean , Humphries Romney M , Kahlmeter Gunnar , Giske Christian G , Turnidge John
Published: February 2020

Recent data on polymyxin pharmacokinetics, pharmacodynamics, toxicity, and clinical outcomes suggest these agents have limited clinical utility. Pharmacokinetics-pharmacodynamics data show a steady-state concentration of 2 μg/mL is required for killing bacteria with colistin minimum inhibitory concentrations of 2 μg/mL. Less than 50% of patients with normal renal function achieve this exposure, and it is associated with high risk of nephrotoxicity. This exposure does not achieve bacterial stasis in pneumonia models. Randomized and observational studies consistently demonstrate increased mortality for polymyxins compared with alternative agents. The Clinical and Laboratory Standards Institute (CLSI) and European Committee on Antimicrobial Susceptibility Testing (EUCAST) are 2 global organizations that establish interpretive criteria for in vitro susceptibility data. CLSI has recently taken the step to eliminate the “susceptible” interpretive category for the polymyxins, whereas EUCAST maintains this interpretive category. This viewpoint describes the opinions of these organizations and the data that were used to inform their perspectives.