bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Phosphorus on Microstructure and Mechanical Properties in NiCr Alloys
Authors: Lian Xin Tong , Sun Wen Ru , Xin Xin , Zheng Dan Dan , Guo Shou Ren
Published: February 2018

Microstructure and mechanical properties of Ni-Cr alloys with various contents of Phosphorus (P) have been investigated. It is found that the increase of phosphorus refined dendritic structures in as-cast alloys and decreased micro-segregation of Chromium (Cr) element. α-Cr which precipitated during hot-rolling process was obviously inhibited by phosphorus because of its prior occupancy on grain boundaries and decreasing precipitation driving force of α-Cr. Tensile and impact properties were examined on samples under different heat treatments. Though the yield strength of as-rolled alloys was increased by precipitation of α-Cr, the elongation and impact energies were reduced. It is worthy to note that impact energies of samples solutioned at 950°C increased with the increasing phosphorus. The results indicated that dislocations are markedly effected by phosphorus which is probably the reason for improving impact energies.
Effect of Extrusion Texture on Mechanical and Electrochemical Properties of Aluminum Alloy Drill Pipe
Authors: Wang Xiao Hong , Peng Zheng Wei , Li Gao Xu , Lin Yuan Hua , Wang Hai Lun
Published: February 2018

Aiming at the special service environment of aluminum alloy drill pipe, in this paper, the influence of extrusion texture on the mechanical and electrochemical properties of aluminum alloy drill pipe was studied. And the macroscopic textures of longitudinal profile and cross section of aluminum alloy drill pipe were tested, and the tensile, compressive and impact mechanical properties were tested, followed by immersion and electrochemical testing. The results show that the texture which 2A12T4 aluminum alloy drill pipe contains is <001> and <111> along the extrusion direction and <223>, <101> in the transverse direction. The test results of mechanical properties show that the extruded texture will affects the mechanical properties of material. When the cross section and longitudinal profile samples of 2A12T4 were soaked in 3.5% NaCl solution at 25°C, 60°C and 90°C, their corrosion resistance are different. The pits of transverse specimens exhibit a dispersed distribution and that of longitudinal specimens are distributed along the extrusion direction.
Effect of Planar Anisotropy and Tension-Compression Asymmetry of CP-Ti on its Deep Drawing Behavior at Room Temperature
Authors: Hao Yong Gang , Lin Peng , Zhang Bao You , Cui Xiao Lei , Zhang Chang Jiang , Chi Cheng Zhong
Published: February 2018

The planar anisotropy (PA) and tension-compression asymmetry (TCA) of the commercially pure titanium (CP-Ti) were investigated through uniaxial tension and compression experiments at room temperature. By deep drawing experiment, the formability and the earing profile for the CP-Ti were studied at room temperature. The deep drawing simulations using the hardening rules of uniaxial tensile or compression curves were compared with experimental results. The results show that the CP-Ti has obvious PA, and the plastic strain ratiosr0,r45andr90are 1.47, 1.64 and 2.05, respectively. The CP-Ti sheet shows the tension-compression asymmetry of yielding and hardening. The TCA also shows obvious PA. The tension-compression yield strength ratio of 0°, 45° and 90° to the rolling direction are 1.12, 1.08, 1.04, and the tension-compression hardening exponent ratio are 0.86, 0.8 and 0.62, respectively. The simulative results without considering TCA indicate that the forming force, the wall thickness and earing profile are not in good agreement with the experimental ones. Therefore, the earing appeared in 45° is contribution of the PA and TCA. The TCA will reduce the thickness of the deep drawing parts, increase the earing ratio and affect the drawing force.
Experimental Study and Numerical Simulation of Microstructure Evolution in Al-Si Eutectic Solidification Process
Authors: Wu Bing , Jiang Ao Lei , Lu Hao , Zheng Hong Liang , Tian Xue Lei
Published: February 2018

A mathematical physical model of microstructure evolution in Al-Si eutectic solidification process based on cellular automaton (CA) model was developed. Before the establishment of the model, the relevant near-eutectic experiments were carried out to analyze the effect of cooling rates measured by temperature curves on the eutectic structure which was observed through optical microscope (OM) and scanning electron microscope (SEM). Then a multiphase nucleation-growth CA model was applied to simulate the Al-Si irregular eutectic structure. The model adopted an alternative nucleation mechanism to investigate the influence of the critical nucleation value associated with solute concentration during solidification process. The growth kinetics took into account the solute and thermal field. According to the crystal structure of nonfaceted eutectic Al and faceted eutectic Si, different capturing rules were employed to calculate the growth of eutectic. In addition, the model was also used to research the irregular eutectic growth under different undercooling conditions. The results revealed that smaller critical nucleation value (absolute value) or higher eutectic undercooling tended to get a more refined eutectic microstructure. By compared with experimental results, it is indicated that the microstructure evolution of Al-Si eutectic growth can be reproduced quantitatively by numerical simulation with this model.
Formation of Face Centered Cubic Titanium Thin Films on MgO(111) Single Crystal Substrate
Authors: Li Lei , Liu Yan , Mao Xiao Nan , Ji Vincent
Published: February 2018

High strength, low density, and excellent corrosion resistance are the main properties that make titanium attractive for a variety of applications. The phase structures and phase transitions of titanium, which are of tremendous scientific and technological interest, have attracted a great deal of attention for many years. In addition to hexagonal close packed α-Ti, high temperature phase β-Ti with body-centered cubic structure and ω-Ti with the hexagonal structure of high-pressure phase, the face-centered cubic structure, which is not in the P-T diagram of titanium, is observed in ultrathin films. In the present paper, the Ti films prepared by magnetron sputtering on MgO(111) single crystal substrate were investigated by means of X-Ray Diffraction (XRD) and High-Resolution Transmission Electron Microscope (HRTEM). The results showed that the Ti films grow epitaxial with a face centered cubic (fcc) structure even the thickness is up to about 50nm. With the thickness increases, the Ti films transformed to hexagonal close packed (hcp) structure and showed an epitaxial growth along (002)hcp-Ti direction. The results show that the onset thickness of fcc-hcp structure transformation is 50-100nm. The temperature and power of sputter affect the formation of fcc-Ti.
Bare Spot Defect on a Hot Dip Galvanized DP Sheet Strip
Authors: Wu Qi Wei , Zhao Ai Min , Yao Shun , Li Zhen
Published: February 2018

Bare spots defect of galvanealed (GA) in High Strength Dual Phase (DP) steel strip with 1.5 % Mn contain was studied in detail. The surface morphologies of spot defects before and after partial and complete removal of the Zn layer, as well as the interface between the outermost coating layer and the sheet substrate were analyzed by optical microscope (OM), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray Photoelectron spectroscopy (XPS), glow discharge optical emission spectrometry (GDOES) and laser scanning confocal microscope(LSCM). It was found that the bare spots defect was composed of a large number of pits with different sizes and depths. There were a lot of Fe - Zn alloy particles distributed in the pits, and many MnO formed on the surface, no effective Fe2Al5 inhibition layer formed. The results showed that the main reasons for the bare spots defect of the GA in High Strength DP steel strip are as follows: a silicon oxide film forms on the substrate during annealing prior to hot dipping because of Mn gathered on the surface of steel strip, thus strip surface wettability with liquid zinc is deteriorated and preventing the formation of the Fe2Al5 inhibition layer during hot dipping. In this paper, the dew point control process is introduced creatively, by increasing the dew point and the hydrogen content in the furnace area, and the bare spot defects on the surface of the high strength duplex steel galvanized sheet are solved.
Effects of the Delivery Tube Diameter on the Qualities of Cu-9.7Sn-0.2P Alloy Powder Produced by Gas Atomization
Authors: Cheng Yu Wan , Xiao Zhi Yu , Zou Hai Ping
Published: February 2018

Gas atomization is one of the most cost-effective methods for preparing spherical powders. The Cu-9.7Sn-0.2P alloy powder for 3D printing was prepared by a self-developed double nozzle gas atomization technique with different deliver tube diameters, and the particle size and shape of the powder were characterized. Results show that the powder particles are mostly nearly spherical, mixed with a few irregular powders. The average O. Bluntness of the powders are 60~70%, the average Outgrowths are lower than 18%. The deliver tube diameter affects the powder characteristics directly. The increase of the diameter increases the particle size of the powder and reduces the sphericity. At the same time, the adhesion of the satellite powder decreases, the flowability becomes better and the oxygen content drop. The surface and internal structure of the powder are mainly cellular and dendritic structures.
Bio-Inspired In Situ Fabrication of 11-Mercaptoundecanoic Acid Coating on Stainless Steel 304 for Corrosion Protection
Authors: Sun Shuo Tian , Lei Yan Hua , Liu Tao , Fan Run Hua , Sun Shi Bin
Published: February 2018

Bio-inspired in situ fabrication of 11-Mercaptoundecanoic Acid was proposed to prepare self-assembled coating of alkanethiolates on SS304 alloy. In this method, the SS304 was coated with a reactive biopolymer – Polydopamine (PDA) by dispersing them in a dopamine solution and mildly stirring at room temperature with subsequent covalent attachment of 11-Mercaptoundecanoic Acid molecules through the interaction between thiol groups and Polydopamine. The formation and surface structure of the coating were characterized by water contact angle measurement, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The electronic properties of such obtained functional film were studied by potentiodynamic polarization curve and EIS in 3.5% NaCl solution. Corrosion protection efficiency near 99 % was evaluated, and the excellent corrosion resistance property could be ascribed to the compact film structure and good seawater stability for modified SS304 surface, especially in limiting the infiltration of Cl-.
Electrodeposition and the Optimization of Molybdenum Layer on Nb-Ti-Si Based Ultra-High Alloys from Aqueous Solution
Authors: Yue Gao , Guo Xi Ping
Published: February 2018

Depositing a molybdenum layer through electrodeposition is a possible and economical way to prepare Mo layer. It could be a new preparation of MoSi2coating on Nb-Ti-Si based alloys combined with halide pack cementation. In this paper, the effects of pre-coated Re layer on the substrate, pH of the electrolyte, water to acetate ratio and the applied current density on the deposition were investigated and optimized to obtain low oxygen content, adherent molybdenum coating on Nb-Ti-Si based alloys. The surface morphology and cross section were characterized by SEM. The thickness of the deposit is about 6 μm and nodules and cracks were observed on the surface. EDS and EPMA analysis suggested the presence of Mo and its oxides in the deposit; XPS results confirmed the presence of Mo, Mo2O3and MoO3in the as-deposited layer. The crystal structure of as-prepared coating was amorphous by the XRD investigation, and the metallic molybdenum was the main existence form of the molybdenum element in the deposit.
Understanding the Inhibition Mechanism of a Supramolecular Complex as the Corrosion Inhibitor for Mild Steel in the Condensate Water
Authors: Fan Bao Min , Wei Bo Yu , Hao Hua , Feng Yun Hao , Yang Biao
Published: February 2018

This work attempted to elucidate the corrosion inhibition mechanism of a supramolecular complex formed between β-cyclodextrin (β-CD) and octadecylamine (ODA) for mild steel in the condensate water. Molecular mechanics simulation was applied to determine the energy favored configuration of the complex and the possible orientation of ODA inside the β-CD cavity. Based on the results of gravimetric measurements, thermodynamics parameters for the adsorption process were calculated through Arrhenius and transition state equations. Scanning electron microscopy and X-ray photo electron spectroscopy were used for surface characterization. Density functional theory calculations (Mulliken charges and molecular electrostatic potential plot) were performed to clarify the adsorption mechanism of β-CD/ODA complex on the steel surface. It was found that four possible configurations of β-CD/ODA complex might be concurrent in the supramolecular system with the stable state in the aqueous solution. ODA molecules could break away from the β-CD cavity and chemically adsorbed on the metal surface, which obeyed the Langmuir adsorption isotherm. The inherent molecular electrostatic properties resulted in the tilted adsorption of ODA.
Raman/Infrared Spectra and Microwave Dielectric Properties of 0.22CaTiO3-0.78(Li0.5Sm0.5)TiO3 Ceramics with MgO Additive
Authors: Ning Fan Fan , Jiang Juan , Zhang Tian Jin
Published: February 2018

0.22CaTiO3-0.78(Li0.5Sm0.5)TiO3+ x wt% MgO (0.25 ≤ x ≤ 2.0) ceramics with pure perovskite structure were prepared by a conventional two-step solid-state reaction process. The effect of different content of MgO additive on the microwave dielectric properties of the 0.22CaTiO3-0.78(Li0.5Sm0.5)TiO3ceramics was investigated in detail. The results of microwave dielectric properties showed that the permittivity (εr) and temperature coefficient of resonant frequency (τf) decreased gradually, while quality factor (Q×f) values increased when the x value increased. Raman spectra and infrared reflectivity spectra were used to study the relationship between vibrational modes and microwave dielectric properties. The harmonic oscillator model was used to fit infrared reflectivity spectra, and the obtained complex dielectric response was extrapolated down into the microwave region. It was found that the complex dielectric spectra were in good agreement with the measured microwave permittivity and dielectric loss. The 0.22CaTiO3-0.78(Li0.5Sm0.5)TiO3+ 0.50 wt% MgO ceramic sintered at 1240°C for 4 h exhibited good microwave dielectric properties with εr= 102.6, Q×f = 5084 GHz (at 3.8 GHz), and τf= -16.3 ppm/°C.
Establishment of Processing Maps for 25vol.% B4CP/AA6061 Composite and its Application in Hot Pack-Rolling Process
Authors: Liu Sheng Pu , Li De Fu , Guo Sheng Li , Du Peng
Published: February 2018

The hot workability and hot pack-rolling process of B4CP/AA6061 composite were studied. The results showed that the addition of B4C particles could effectively promote the dynamic recrystallization (DRX) process of the composite. DRX and DRX grains growth were dominant deformation mechanism during hot deformation of B4CP/AA6061composite. Typical instability defects included micro voids and particle aggregation. The optimum processing parameters for good workability were obtained in the temperature range of 450°C-500°C and strain rate range of 0.01s-1-0.1s-1. According to the flow stress curves and processing maps, a temperature of 500°C and a rolling velocity of 40 mm/s were chosen for pack-rolling experiments. The pack-rolled composite sheets in the RD and TD showed more homogeneous DRX grains than as-HIPed microstructures, which might indicate that hot pack-rolling could lead to more homogeneous microstructures without any edge cracking and surface cracking.
3D Printing of Carbon Fiber Reinforced Plastics and their Applications
Authors: Zhou Wei Dong , Chen Jian Sheng
Published: February 2018

3D printing of carbon fiber reinforced plastics can produce lightweight components with higher efficiency and more complex structure. For the short carbon fiber reinforced plastics, the composites are firstly made by compounding, then they are processed to filaments, powders or other needed forms, finally the components are printed by Fused Deposition Modeling (FDM), Selected Laser Sintering (SLS) or other methods. The tensile strength of the nylon-based component is more than 70 MPa. Companies such as EOS, Stratasys and Farsoon can provide the materials and equipments. For the continuous carbon fiber reinforced plastics, the divided carbon fibers and plastic filaments or impregnated carbon fiber filaments are firstly prepared, then the components are printed by FDM or other methods. The average tensile strength of the nylon-based component is more than 200 MPa. Companies such as Markforged and Arevo Labs have commercialized the 3D printing equipment/platform for the continuous fiber reinforced plastics.
Thermodynamic Calculation of Liquidus Projection of Multiple Aluminum Alloys
Authors: Zhao Jing Rui , Cheng Kai Ming , Du Yong , Zhang Li Jun
Published: February 2018

Most aluminum alloys used in industrial manufacturing are multi-component systems. Unfortunately, multi-component systems are still lack of systematic research. The lack of research is especially evident for the liquidus surface projection of the multi-component system where most of the projections are currently drawn by hand. Thermodynamic calculations were performed for the Al–Cu–Mg–Mn quaternary system and the A1–Cu–Fe–Mg–Mn quinary system. The temperatures and compositions of the liquidus invariant reactions in the A1–rich corner for the two systems were calculated and compared with the experimental data. The current work provides a straightforward and accurate expression for the liquidus surface projections of multi-component systems. The expressions will facilitate the understanding of the multi-component alloy systems that are frequently used in industrial applications.
Influence of Initial Defects on the Mechanical Properties of Single Crystal Copper: Discrete Dislocation Dynamics Study
Authors: Zhang Ming Yi , Zhong Min , Yuan Shuai , Bai Jing Song , Li Ping
Published: February 2018

In this paper, three dimensional discrete dislocation dynamics method was used to quantitatively investigate the influence of initial defects on mechanical response of single crystal copper. Both the irradiation defects (interstitial loops) and random dislocation lines with different densities are considered. The simulation results demonstrate that the yield strength of single crystal copper is higher with higher initial dislocation density and higher interstitial loop density. Dislocation density increases quickly by nucleation and multiplication and microbands are formed during plastic deformation when only the random dislocation lines are initially considered. Characteristics of microbands show excellent agreement with experiment results. Dislocation multiplication is suppressed in the presence of interstitial loops, and junctions and locks between dislocations and interstitial loops are formed. Dislocation density evolution shows fluctuation accompanied with strain-stress curve fluctuation.
Glucose-Responsive Hydrogels Based on Phenylboronic Acid
Authors: Ma Yuan Yuan , Liu Han Ting , Ma Jing Hong , Gong Jing Hua
Published: February 2018

Glucose-sensitive hydrogels that have three-dimensional network structure can respond to the glucose, which arouses great interest in biochemistry and biomedical. As a glucose sensitive group, Benzene boric acid has the advantages of good stability, low toxicity and no immune rejection. In this study, synthetic 3-acrylamidophenylboronic acid (AAPBA) with N-isopropylacrylamide (NIPAM) were used to fabricate glucose-responsive hydrogels via free radical polymerization in aqueous media. Several key factors such as polymer compositions and polymer concentrations have been investigated to sensitivity of the hydrogels. These polymers can respond in the presence of glucose, and the monomer ratio has a significant influence on the response behavior of hydrogels. Therefore, it has potential applications in the field of insulin-controlled drug delivery system and biosensor.
Evaluation of Foaming and Nucleation and Growth Mechanism of Soy-Based Polyurethane Foams
Authors: Zhang Xiao , Zhou Xin Xing
Published: February 2018

The foaming and nucleation and growth mechanism of soybean oil-based polyurethane (SPU) were determined by the degree of hydrogen bonding, and isocyanate groups. New types of SPU were prepared by the different NCO/OH molar ratio (isocyanate index) from 1.0 to 2.0 in a soy polyol/polyether polyol (MDI) system. Foaming and nucleation and growth mechanisms of SPU were studied by fluorescence microscope (FM), scanning electron microscope (SEM), energy disperse spectroscopy (EDS) and Fourier transform infrared spectroscopy (FT-IR). It indicated that the isocyanate index affected remarkably the velocity of foaming and the critical nucleation radius of SPU and the ester functional group increased with the increase of isocyanate index. The nucleation and growth phase transition were dominated by the diffusion controlled nucleation and isocyanate content was the key factor of foam formation.
Preparation of Graphene/N-TiO2 Nanoclusters by One Step Anodic Oxidation for Visible-Light-Driven Hydrogen Production
Authors: Lai Min , Su Dong , Li Chang Xin , Liu Yan , Zhang Yan Zong
Published: February 2018

Titanium dioxide, as a promising photocatalytic material, has been widely used in the fields of environmental pollution control and photocatalytic water splitting to generate hydrogen. In this paper, graphene and N-doping TiO2composite film (GR/N-TiO2) electrode had been grown on titanium foil by one-step anodization, which was simple, time-saving and low cost. The electrode surface was lotusroot-like nanoclusters structure, which had a large specific surface area. The electrode exhibited an excellent optical absorption from ultraviolet to near infrared (200-2500 nm). This was due to the synergistic effects of graphene and N element, and the presence of oxygen vacancy defects. The results showed that the electrode had good electrochemical performances under simulated sunlight, its photocurrent density was about 0.7 mA/cm2, the light conversion efficiency was 0.35 %, and the hydrogen production rate was 34 μmol h-1cm-2. Thus, the prepared GR/N-TiO2film electrode had an excellent hydrogen production activity under sunlight and the potential of converting solar energy into hydrogen energy directly.
Microfluidic Synthesis and Electrochemical Performance of Ternary Metals Nanoalloy: FePtSn
Authors: Ma Ju Gang , Wang Jun Mei , Li Shuai , Song Yu Jun
Published: February 2018

The ternary FePtSn alloy nanoparticles (NPs) were synthesized via a simple programmed microfluidic process, showing a great electrochemical performance in methanol oxidation reaction (MOR). The synthesis process exhibited convenient and spatial-temporal kinetics control of the NPs formation for a narrow size distribution, ultra-small (~2nm) and good dispersion features. The morphology, crystal structure and composition of FePtSn NPs were characterized by transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), powder X-ray diffraction (XRD). FePtSn/C nanocatalyst ink could be further prepared by mixing the as-synthesized or annealed FePtSn NPs with carbon black powder and nafion. Their electrocatalytic performances were tested by the electrochemical work station. By contrast, the annealing treatment made more active sites exposed and facilitated the catalytic performance of FePtSn/C NPs. The electrochemical active surface areas (ECSAs, 42.8m2/g), catalytic activity (If: 588.1 mA/mg-Pt) and electrochemical durability of FePtSn/C nanocatalysts after annealing were greatly improved, comparing with as-synthesized samples and commercial Pt/C nanocatalysts for MOR. In addition, the onset potential of annealed FePtSn/C nanocatalysts was improved, much better than the commercial Pt/C nanocatalysts.
Aging Behavior of A356.2 with Yb Modified
Authors: Zhang Shao Chen , Wang Zhi Bin , Dong Yun Fan , Wang Kang , Wang Qi , Leng Jin Feng
Published: February 2018

The effect of aging treatment on the aging hardening of 0% Yb and 0.4% Yb modified A356.2 alloy was investigated by hardness measurements and optical microscope. In this work, A356.2 was first subjected to 535°C for 5h and then subjected to 150°C, 180°C for 2h-12h hours. Results show that during aging process, there was a hardness peak along the increasing of aging temperature and time. With increasing aging progress, the morphology of Si phases became shorter and spherical. After optimum time, Si phases was coarse and the dendritic grain was broken. The peak-aged of unmodified alloys was 150°C for 10h and 180°C for 6h，and corresponding hardness values were 62.35HB and 77.10HB, respectively. With Yb addition, the hardness reached 87.58HB and 98.28HB on peak aging of 150°C/8h and 180°C/ 6h, respectively. The greatest degree of hardness was increased by 40.46% and 27.47%, combined with no Yb addition. XRD shows the interplanar crystal spacing of A356.2 with 0.4% Yb addition, which was larger than fresh A356.2 alloy. When adding 0.4%Yb under 180°C for 6h aging progress, the ultimate tensile strength was 284 MPa 12.7% increasing compared with former work.
The Martensitic Transformation in Ti-6Al-4V
Authors: Xu Zhi Chao , Kriegel H.P.
Published: February 2018

The effect of heat treatment on the phase transformation of Ti-6Al-4V alloy was investigated. This heat treatment consisted of solution treatment at 850°C,900°C,950°Cfor 1h and subsequent water quenching. The phase transformation data was obtained by X-ray diffraction and differential scanning calorimetry (DSC).The differences were observed in the changes of lattice parameters of martensite phase among the different solution temperature. The volume of single cells for a' phase increases from 34.84 Å3 to 35.09 Å3 and then decreases to 34.63 Å3 with the solution temperature increased. These changes are believed to be due to partitioning of vanadium in b phase and its strong effect on the lattice parameter of a' martensite phase. The nucleation rate function has been obtained by thermodynamic theory. Based on these equations, it could be proved that the nucleation rate of martensite should be increased with the increase of the content of vanadium and the decrease of aluminum in b phase.
Effect of Borax on Properties of Potassium Magnesium Phosphate Cement
Authors: Wen Jin Bao , Zhang Li Xia , Tang Xiu Sheng , Huang Guo Hong , Zhu Ye Ran
Published: February 2018

The effects of borax on the setting time, compressive strength, bond strength, drying shrinkage and pH value were investigated for potassium magnesium phosphate cement (MKPC). The results show that with the increase of borax dosage, the setting time is gradually extended, both compressive strength and bond strength are greatly decreased, the drying shrinkage rate is increased. Especially high dosage of borax, the extension of setting time is more obvious. Compared with that without borax, when the dosage of borax is 12.5%, setting time can be prolonged by 214.8%.The influence of borax dosage on the time-dependent effect of compressive strength shows that when the dosage of borax is 2.5%~5.0%, compressive strength increases rapidly from 4h to 1d, and increases relatively slowly from 1d to 3d. When borax dosage is less than 2.5% or higher than 5%, the law of time-dependent effect of compressive strength is the opposite. Compared to borax prior to magnesia addition, the pH value of the system is larger and the time of inflection point is advanced when borax and magnesia are mixed together at the same time. The increase of borax dosage can reduce the pH value of the system, and decrease the rising rate of pH value, at the same time the required time when the final pH value is relatively stable is longer.
The Impact of Different Alkali Metal Ions on Photoluminescence Properties of Ca10M(PO4)7:Eu2+ (M: Li, Na, K)
Authors: Zhao Jian Wen , Dong Jun , Zhou Jian , Wen Xiao Qiang , Yang Shu Zhong , Luo Ling Shan , Wu Di , Liu Wen Wen , Xiao Hou Qun , Zhou You Chi , Xiao Yin Yi , Yang Fan
Published: February 2018

A series of novel luminescent materials Ca10M(PO4)7:Eu2+(M: Li, Na, K) were synthesized by the solid-state reaction. The previous literatures indicate that the doped different alkali metal ions can only lead to regular shift of the emission and excitation spectra. Howerver, in this paper, we found the result that these three kinds of phosphors showed huge differences between the emission spectra intensity as well as the positions of the excitation and emission spectra peaks. No any regulars can be found. In order to explore it, crystal structure, the performance of photoluminescence spectra and CIE coordinates have been systematically investigated and discussed. In Ca10Li (PO4)7, Ca10Na (PO4)7and Ca10K(PO4)7host lattices, the positions of the cations are different, leading to three different crystal structures. Besides, the coordination conditions of the luminescent centers Eu2+ions are also changed by the incorporation of the alkali metal ions. Thus the enormous disparity on the luminescence intensity as well as the excitation and emission peak positions may be ascribed to these three quite different crystal fields and different coordination numbers of the luminescent central ion in the Ca10M(PO4)7:Eu2+(M: Li, Na, K) phosphors.
Orientation Process for Newly Credentialed Athletic Trainers in the Transition to Practice
Authors: Thrasher Ashley B. , Walker Stacy E.
Published: February 2018

Context: 

Orientation is an important part of socialization and transition to practice, yet the orientation process for newly credentialed athletic trainers (ATs) is unknown.

Objective: 

To determine how newly credentialed ATs are oriented to their roles.

Design: 

Cross-sectional study.

Setting: 

Online survey.

Patients or Other Participants: 

Three hundred thirty-two of 1835 newly credentialed ATs (18%) certified and employed between January and September of 2013 completed the survey (129 men, 203 women; age = 23.58 ± 2.54 years).

Data Collection and Analysis: 

The survey consisted of demographic information (eg, employment setting, job title) and 2 sections: (1) orientation tactics and (2) usefulness of orientation tactics. For the first section, participants identified if various orientation tactics were included in their orientations (eg, policies and procedures review). For the second section, participants identified how useful each orientation tactic was on a Likert scale (1 = not useful, 4 = very useful). Descriptive statistics were calculated for each survey item. Mann-Whitney U and Kruskal-Wallis tests were used to determine differences between demographic characteristics and orientation tactics. A Bonferroni correction accounted for multiple comparisons. A panel of experts established the content validity of the survey. The Cronbach α was used to establish internal consistency (α = 0.802)

Results: 

The most common orientation tactics were meeting with supervisors (n = 276, 82.9%) and staff members (eg, coaches; n = 266, 79.9%) and learning responsibilities (n = 254, 76.2%). The least common orientation tactics were simulation of the emergency action plan (n = 66, 19.8%) and preceptor development (n = 71, 21.3%); however, preceptor development was not applicable to many participants. The most useful orientation tactics were simulating the emergency action plan (3.45/4.0) and meeting with staff members (3.44/4.0). Participants who felt their orientation prepared them for their roles were exposed to more tactics during orientation (Mann-Whitney U = 17 212, P < .001).

Conclusions: 

Many tactics were used to orient newly credentialed ATs to their roles, but orientations varied based on the practice setting.
Telomere length as a potential biomarker of coronary artery disease
Authors: Bhattacharyya Joyeeta , Mihara Keichiro , Bhattacharjee Deborshi , Mukherjee Manjarí
Published: February 2018

Coronary artery disease (CAD) is a multifactorial disease whose prevalence remains unabated especially in developing countries. Both lifestyle factors and genetic predisposition contribute to this disorder. Though notable achievements have been made in the medical, interventional and surgical management of CAD, the need for its prevention is more important. Among other modalities, this calls for defining evidence-based new biomarkers, which on their own or in combination with other known biomarkers may predict the risk of CAD to enable institution of appropriate preventive strategies. In the present communication, we have discussed the usefulness of shortening of telomeres as a potential biomarker of CAD. Clinical research evidence in favour of telomere shortening in CAD is well documented in different ethnic populations of the world. Establishing a well-standardized and accurate method of evaluating telomere length is essential before its routine use in preventive cardiology.
Peripheral blood mononuclear cells of patients with latent autoimmune diabetes secrete higher levels of pro- & anti-inflammatory cytokines compared to those with type-1 diabetes mellitus following in vitro stimulation with β-cell autoantigens
Authors: Badal Darshan , Kumar Rajendra , Paul Mahinder , Dayal Devi , Bhansali Anil , Bhadada Sanjay Kumar , Kumar Rajesh , Sachdeva Naresh
Published: February 2018

Background & objectives:

Type-1 diabetes mellitus (T1DM) and latent autoimmune diabetes in adults (LADA) share similar pathological features but differ in age of onset and progression. There is a scarcity of information on differences in CD4+ T-cell responses, particularly, cytokine secretion, between the two forms of autoimmune diabetes. Here proliferative potential and concentration of pro- and anti-inflammatory cytokines secreted by peripheral blood mononuclear cells (PBMCs) of T1DM and LADA patients were compared, after in vitro stimulation with β-cell autoantigens.

Methods:

A total of 19 patients with LADA, 37 with T1DM and 20 healthy controls were compared on the basis of lymphocyte proliferation and secretion of pro- and anti-inflammatory cytokines belonging to different T-helper types after in vitro stimulation of PBMCs with insulin and glutamic acid decarboxylase 65 (GAD65).

Results:

Following insulin stimulation, LADA group secreted higher concentration of interleukin-17 (IL-17) (P=0.02) and had higher proportion of interferon gamma (IFN-γ) secretors (P<0.001) than T1DM group. Post-GAD65 stimulation, higher proportion of LADA patients secreted IL-23 than T1DM group (P=0.02). Proportion of responders, as well as levels of secreted IL-10, were significantly higher in LADA than T1DM group, following stimulation with both insulin (P=0.01) and GAD65 (P=0.03). A significant positive correlation was observed between body mass index and IL-17 levels (r=0.41, P=0.04) and fasting plasma C-peptide with IL-10 levels (r=0.37, P=0.04).

Interpretation & conclusions:

There are differences in the portfolio of cytokine secretion in diabetic subjects with varying rates of β-cell destruction as LADA subjects secrete higher levels of both pro- and anti-inflammatory cytokines on exposure to β-cell autoantigens, thus highlighting another distinguishing feature in the pathophysiology of the two forms of autoimmune diabetes.
Modelling of cerebral tuberculosis in BALB/c mice using clinical strain from patients with CNS tuberculosis infection
Authors: Husain Aliabbas A. , Gupta Umesh Datta , Gupta Pushpa , Nayak Amit R. , Chandak Nitin H. , Daginawla Hatim F. , Singh Lokendra , Kashyap Rajpal Singh
Published: February 2018

Background & objectives:

Central nervous system (CNS) infection caused by Mycobacterium tuberculosis (MTB) is the most severe form of extrapulmonary tuberculosis (EPTB) due to a high level of mortality and morbidity. Limited studies are available on CNS-TB animal model development. The present study describes the development of a murine model of CNS-TB using a clinical strain (C3) isolated from the cerebrospinal fluid (CSF) of CNS-TB patients.

Methods:

Groups of mice were infected by the intravenous route with MTB C3 strain isolated from the CSF of CNS-TB patients. Brain and lung tissue were evaluated for bacterial burden, histopathology and surrogate markers of TB infection at 30 and 50 days post-infection.

Results:

Mice infected intravenously with MTB C3 strains showed progressive development of CNS disease with high bacillary burden in lungs at the initial stage (30 days), which eventually disseminated to the brain at a later stage (50 days). Similarly, high mortality (60%) was associated in mice infected with C3 strain compared to control.

Interpretation & conclusions:

The study showed development of a novel murine model of CNS-TB using the C3 strain of MTB that replicated events of extrapulmonary dissemination. The developed model would be helpful in understanding the pathogenesis of CNS-TB infection for the development of improved therapeutic interventions in future.
A New Modified Method for Inserting Iliosacral Screw versus the Conventional Method
Authors: Javidmehr Sina , Golbakhsh Mohammad Reza , Siavashi Babak , Talebian Parham , Dehnokhalaji Morteza , Zehtab Mohammad Javad , Bozorgmanesh Mohammadreza
Published: February 2018

Study Design

Methodological study.

Purpose

To our knowledge, this is the first study to introduce a new modified method for inserting iliosacral screws and to compare its results with those of a conventional method.

Overview of Literature

Previous techniques, such as open reduction and internal fixation, are associated with perioperative hemorrhage, postoperative infection, and neurological deficits. Although percutaneous iliosacral screw insertion confers the advantage of being minimally invasive, leading to less blood loss and a low postoperative infection rate, it harbors the risk of screw malpositioning due to narrow sacral proportions and a high interindividual variability.

Methods

Nine cadaveric pelvises were included in this study, with one hemipelvis of each being assigned to the new modified method and the other to the conventional iliosacral screw insertion method. In the new modified method, the guidewire entry point was determined using a lateral sacral X-ray. To do so, we first identified the anterosuperior quadrant of the S1 body on one hemipelvis. The anterosuperior quadrant was further divided into four imaginary quadrants, and the guidewire was inserted into the posteroinferior quadrant. The guidewire trajectory was perpendicular to the sagittal plane so that the guidewire resembled a single point in the lateral sacral view. Guidewires were inserted into corresponding hemipelves using the conventional method as described in the literature. Subsequently, an axial computed tomography scan with 1-mm fine cuts was obtained, and sagittal and coronal views were reconstructed. The distance of the guidewire from the sacral canal, anterior sacral cortex, and first sacral foramen was measured in axial, sagittal, and coronal views. The minimum measurement among different views was defined as the safety index of the insertion methods. The conventional and new modified methods were then compared in terms of safety and duration of the procedure.

Results

The minimum distance of the guidewire from the S1 foramen and anterior sacral cortex was not significantly different between the two methods. However, the minimum distance between the guidewire and sacral canal was significantly greater in the new modified method than in the conventional method. The duration of guidewire insertion was significantly shorter in the new modified method than in the conventional method.

Conclusions

This new modified method of iliosacral screw insertion could be safely and simply implemented while taking less surgical time than the conventional methods.
The Relationship between Sacral Kyphosis and Pelvic Incidence
Authors: McKay George , Torrie Peter Alexander , Dempster Georgina , Bertram Wendy , Harding Ian
Published: February 2018

Study Design

Retrospective cohort study.

Purpose

Evaluate the fixed anatomical parameter of sacral kyphosis (SK) and its relationship with pelvic incidence (PI).

Overview of Literature

Pelvic parameters determine pelvic and lumbar spinal position. Studies have defined normative values, and have evaluated the role of these parameters in clinical practice. It has been suggested that a ratio of sacral slope (SS)/PI <0.5 predisposes to spinal pathology. PI=SS+pelvic tilt (PT) and therefore for a given PI, patients with a higher SS due to an elevated SK will potentially predispose to an unfavourable SS/PI ratio.

Methods

CT measurements of SS and PI were made in 100 consecutive patients from our database. Imagings without clear landmarks were excluded. PI and SK were measured using standardised techniques. Pearson's correlation was used to assess association between PI and SK, in addition to the correlation between age and the pelvic parameters. Gender specific values for PI and SK were compared using an unpaired Student t-test.

Results

Ninety-five patients (52 females) with a mean age 51.3 years were available for analysis. A strong positive correlation between the PI and the SK was identified (Pearson's coefficient=0.636, R2 value=0.404). Neither PI nor SK had a statistically significant correlation with age (p=0.721 and p=0.572, respectively). The mean values of both the PI and SK were statistically significantly lower in females when compared to males (p=0.0461 and p=0.0031, respectively).

Conclusions

A strong correlation between PI and SK exists and is a reflection of different pelvic morphologies. SK partially determines SS and a relatively high SK compared to PI will result in less ability to change PT and a potentially unfavourable SS/PI ratio, which could theoretically contribute to clinical pathology.
Does Subcutaneous Infiltration of Liposomal Bupivacaine Following Single-Level Transforaminal Lumbar Interbody Fusion Surgery Improve Immediate Postoperative Pain Control?
Authors: Tomov Marko , Tou Kevin , Winkel Rose , Puffer Ross , Bydon Mohamad , Nassr Ahmad , Huddleston Paul , Yaszemski Michael , Currier Bradford , Freedman Brett
Published: February 2018

Study Design

Retrospective case-control study using prospectively collected data.

Purpose

Evaluate the impact of liposomal bupivacaine (LB) on postoperative pain management and narcotic use following standardized single-level low lumbar transforaminal lumbar interbody fusion (TLIF).

Overview of Literature

Poor pain control after surgery has been linked with decreased pain satisfaction and increased economic burden. Unfortunately, opioids have many limitations and side effects despite being the primary treatment of postoperative pain. LB may be a form of pre-emptive analgesia used to reduce the use of postoperative narcotics as evidence in other studies evaluating its use in single-level microdiskectomies.

Methods

The infiltration of LB subcutaneously during wound closure was performed by a single surgeon beginning in July 2014 for all single-level lumbar TLIF spinal surgeries at Landstuhl Regional Medical Center. This cohort was compared against a control cohort of patients who underwent the same surgery by the same surgeon in the preceding 6 months. Statistical analysis was performed on relevant variables including: morphine equivalents of narcotic medication used (primary outcome), length of hospitalization, Visual Analog Scale pain scores, and total time spent on a patient-controlled analgesia (PCA) pump.

Results

A total of 30 patients were included in this study; 16 were in the intervention cohort and 14 were in the control cohort. The morphine equivalents of intravenous narcotic use postoperatively were significantly less in the LB cohort from day of surgery to postoperative day 3. Although the differences lost their statistical significance, the trend remained for total (oral and intravenous) narcotic consumption to be lower in the LB group. The patients who received the study intervention required an acute pain service consult less frequently (62.5% in LB cohort vs. 78.6% in control cohort). The amount of time spent on a PCA pump in the LB group was 31 hours versus 47 hours in the control group (p=0.1506).

Conclusions

Local infiltration of LB postoperatively to the subcutaneous tissues during closure following TLIF significantly decreased the amount of intravenous narcotic medication required by patients. Well-powered prospective studies are still needed to determine optimal dosing and confirm benefits of LB on total narcotic consumption and other measures of pain control following major spinal surgery.
Influence of users’ computer self-efficacy and perceptions on satisfaction with electronic libraries in northern Nigerian universities
Authors: Sadiku Shuaibu A. , Issa Abdulwahab O. , Salman Abdulsalam A. , Omopupa Tunde K. , Rabiu Nafisa
Published: February 2018

In recent times, advancement in technology has penetrated areas of library functions, especially, the establishment of an electronic library (e-library) system that has become commonplace in Nigeria. Studies have shown a low level of users‟ satisfaction with these resources. Thus, this study examined the influence of users‟ computer-self-efficacy and perception on users‟ satisfaction with e-libraries in Northern Nigerian universities. Descriptive survey research was adopted. A population of 7,028 users was considered out of which 1,406 was randomly sampled and used. A questionnaire was used to collect data. Hypotheses were tested with Spearman Rank-Order Correlation. Findings revealed that computer self-efficacy of users with e-libraries were high, even though their perceptions of e-libraries were low. There was a strong relationship between computer self-efficacy and satisfaction with e-library (r(951) = .164, p = .000), a positive correlation between perceptions and satisfaction with e-library (r(951) = .334, p = .000). It was therefore concluded that the satisfaction of users with e-libraries in the universities in Northern Nigeria would largely be influenced by their level of computer self-efficacy and perception. The study recommended the acquisition of relevant skills by the user for satisfactory utilization of the e-libraries. In particular, users should be assisted in identifying high-quality e-library resources.Keywords: Computer self-efficacy, e-library, users’ perception, users’ satisfaction, Northern Nigeria
Design of an adaptive overcurrent protection scheme for microgrids
Authors: Awaad Mohamed , Mekhamer S.F. , Abdelaziz Almoataz Y.
Published: February 2018

Microgrid is a new phenomenon regarded to Distributed Generation (DG) penetration in the existing distribution systems. In this paper adaptive over current (OC) protection technique for a distribution system with DG penetration is proposed. This scheme takes into account general protection requirements, impacts of DG on protection system and protection coordination. A part of IEEE 13 nodes radial distribution test feeder is taken as a study case to test the effectiveness of the proposed scheme using ETAP software.Keywords: Distributed Generator, Microgrids, Adaptive overcurrent protection, Protection Coordination
Effect of Microstructure on the Corrosion Performance of 5% Cr Steel in a CO2 Environment
Authors: Wu Tao , Wu Huibin , Niu Gang , Li Tao , Sun Ruiyan , Gu Yang , Yuan Rui
Published: February 2018

In this study, the CO2 corrosion behavior of 5% Cr martensite and ferrite-pearlite steels has been investigated by analyzing their corrosion products, surface morphologies, cross-sectional morphologies, and elemental distributions. The results of electrochemical studies demonstrated that 5% Cr steels with different microstructures exhibited pre-passivation characteristics, which decreased their corrosion rates. The produced passivating surface layers consisted of Cr-rich compounds, which significantly affected steel corrosion properties, while the correlation between the observed Volta potential drops and depletion of Cr contents at the grain boundaries, and the corrosion behavior of 5% Cr steel was determined via scanning Kelvin probe force microscopy.