bluuebunny/crossref_metadata_2025 huggingface dataset:
Penetration Performance of Shaped Charge Jets Using Insensitive Munition: Simulative and Experimental Studies
Authors: Ahmed Mukhtar , Huang Zheng Xiang , Malik A.Q. , Zu Xu Dong , Xiao Qiang Qiang , Ahmed Munir
Published: May 2015

The simulation and experimental studies of the Jets obtained from different conical liners from a charge having 56mm-diameter is presented in this paper. An OFHC copper liner of thickness 1 mm and 54 mm-diameters is used for jet formation analysis. Charge ignition is made by using Point detonation method. The simulation results are obtained from Ansysis Autodyn 2-D hydrocode. Experiments are conducted for a charge having 600 conical liner. Flash X-ray Radiography is used for image capturing. The performance capacity of standard shaped charge is predicted by its penetration against steel target. It is observed that kinetic energy of the jet decreases as angle increases, also total energy of the explosive increases and hence the Ratio of the K.E of the jet to the total energy of the explosive decreases as the angle increases. Simulation results are compared with the experimental results. It is observed that simulation results are in favorable agreement within acceptable range of error with the experimental results.
An Image Analyzing Method by a Homology Concept for Fracture Surfaces
Authors: Takiyama Akihiro , Nakane Kazuaki , Kida Katsuyuki
Published: May 2015

From early 20th, the homology have been studied as a branch of mathematics. It has been one of a major topic in mathematics and applied in many scientific fields. The homology can be regarded as a mathematical concept of quantifying the contact degree. Because it belongs to modern mathematics, advanced knowledge of mathematics are required to understand this concept. Fortunately, since the definition of the homology is very simple in two-dimensional case, we can easily apply this to image analyzing methods.
Fracture surface is composed of a process that cracks grow. If these cracks contact one another, rupture occurs. Progress of the fracture would vary due to the effect of external force. We identify the rapid and the fatigue fracture surface by a homology method. By analyzing the state of fracture via a homology method, it is believed that the cause of fracture can be estimated.
The Effects of Ca(OH)2 on the Steam Gasification Process of Acid-Washed and Raw Lignite
Authors: Shuai Chao , Hu Song , Xiang Jun , Su Sheng , Sun Lu Shi , Wang Yi
Published: May 2015

The effect of Ca (OH)2 prepared by the wet-mixing method on acid-washed and raw lignite steam gasification process at 800°C were analyzed in a spout-fluid bed reactor. The addition of Ca (OH)2 on acid-washed lignite obviously increased the coal conversion, gas yield and reduced the tar yield, and the Ca (OH)2 addition on raw lignite significantly reduced the tar yield but just slightly increased the coal conversion and gas yield. As a catalyst, Ca (OH)2 can promote the tar steam reforming in the gasification process. Based on GC-MS data, it can be deduced that Ca (OH)2 has different catalytic activity on the steam reforming of tar with different molecular structures. Aliphatic hydrocarbons, Class 2 and Class 5 tars were clearly catalytic reformed, while the concentration of Class 4 tars increased. The CO concentration decreased and the CO2 and H2 concentration increased with the addition of Ca (OH)2 on both acid-washed and raw lignites, which was mainly caused by the catalytic effect of Ca (OH)2 on WGS reaction. The effect of Ca (OH)2 addition on acid-washed lignite was more significant than on raw lignite, and no adsorption of CO2 was detected in the process by using active carbon as a model compound.
Hot Deformation and Cracking during Compression of 21-4N Steel
Authors: Oh Ho Kyun , Park Sang Min , Hong Sun Ig
Published: May 2015

Hot compressive deformation and cracking behaviors of cast 21-4N steel were investigated over a temperature range between 900°C~1250°C. The strength of the specimen at the outer surface of ingot is greater than that in the inner part because of the initial rapid solidification and corresponding fine structure at the outer surface. The initial flow stress hump in the stress-strain curves can be attributed to the dynamic recrystallization, which requires the initial strain energy build-up before the activation of grain nucleation process. With increase of temperature the critical stain for dynamic recrystallization decreases and at high enough temperatures, no critical strain for the build-up of strain energy is needed. At temperatures between 1000°C and 1200°C, homogeneous deformation occurred and no cracks were observed even after 50% strain. The cracks observed below 1000°C could be associated with the more difficult plastic flow in the presence of carbides and nitrides. The presence of fatal crack at 1250°C and the loss of hot ductility can be attributed to the partial melting in austenite grain boundaries at high temperatures.
The 6N01 Aluminum Components by Orthogonal Design Optimization
Authors: Xu Feng Lin , Li Bo , Wang Hong Bo , Wu Jin Jin , Li Dong Feng , Zhou Cheng Hou , Wang Xiao Min
Published: May 2015

In this study, we designed four components of 6N01 aluminum alloy by orthogonal design, and analyzed the effect of the different elements for the mechanical properties and microstructure of the designed material after casting, homogenization annealing, extrusion treatment and natural aging. Considering the above series of tests of the data indicators, and thus orthogonal filter out two materials that all aspects of performance are more excellent.Keywords: orthogonal design; 6N01 aluminum alloy; mechanical properties; microstructure
Effect of Shot Peening Coverage on Fatigue Strengths of Steels and Aluminum Alloy
Authors: Sakamoto Junji , Lee Yong Sung , Cheong Seong Kyun
Published: May 2015

The relations between shot peening coverage and fatigue strength in the quenched-tempered and annealed medium-carbon steels and aluminum alloy A7075-T6 were experimentally studied using a rotating bending fatigue testing machine. It was found that the fatigue strengths of the annealed steel and aluminum alloy were increased by shot peening. On the other hand, the fatigue strength of the quenched-tempered steel were not increased by shot peening. Same shot peening condition causes the positive effect and the negative effect depending on the type of material. Moreover, the valuable coverage might depend on the type of material. More detailed work is necessary to resolve the issue.
An Atomistic View of Grain Boundary Diffusion
Authors: Mishin Yuri
Published: May 2015

This paper presents an overview of recent computer simulations of grain boundary (GB)diffusion focusing on atomistic understanding of diffusion mechanisms. At low temperatures when GBstructure is ordered, diffusion is mediated by point defects inducing collective jumps of several atomsforming a chain. At high temperatures when GB structure becomes highly disordered, the diffusionprocess can be analyzed by statistical methods developed earlier for supercooled liquids and glasses.Previous atomistic simulations reported in the literature as well as the new simulations presented in thispaper reveal a close similarity between diffusion mechanisms in GBs and in supercooled liquids. GBdiffusion at high temperatures is dominated by collective displacements of atomic groups (clusters),many of which have one-dimensional geometries similar to strings. The recent progress in this fieldmotivates future extensions of atomistic simulations to diffusion in alloy GBs, particularly in glassformingsystems.
General Approach to Diffusion under a Stress in Metals and Interstitial Alloys
Authors: Nazarov Andrei , Mikheev Alexander
Published: May 2015

One of the main aims of our work is to obtain general equations for the diffusion fluxes under strain that give the possibility for using these equations at low temperatures, as in this case the strain influence on the diffusion fluxes is manifested in maximal degree. Our approach takes into consideration that the strains can alter the surrounding atom configuration near the jumping atom and consequently the local magnitude of the activation barrier and a rate of atom jumps. The approach is derived under assumptions that the total energy depends on the pair distances only and the attempt frequencies are the same for all jumps. The rates of atom jumps in different directions define the flux density of the defects. Now we take into account that the strain tensor is different at the saddle point and at the rest atom position, that differentiates our approach from previous ones. As a result, general equations for the vacancy fluxes and impurity fluxes are obtained for fcc and bcc metals. These equations differ significantly from those obtained earlier.
Atomic Transport in Nano-Crystalline Silicides Studied by In Situ Auger Electron Spectroscopy: Interfacial Reaction Effect
Authors: Portavoce Alain , Hoummada Khalid , Dahlem Franck , Girardeaux Christophe , Lalmi Boubekeur
Published: May 2015

Silicide growth via reaction between a metallic film and a Si substrate has been well documented. In general, atomic transport kinetic during the growth of silicides is considered to be the same as during equilibrium diffusion, despite the reaction and its possible injection of point-defects in the two phases on each side of the interface. To date, the main studies aiming to investigate atomic transport during silicide growth used immobile markers in order to determine which element diffuses the fastest during growth and in which proportion. The quantitative measurements of effective diffusion coefficients during growth was also performed using Deal-and-Groove-type of models, however, these effective coefficients are in general not in agreement with the interdiffusion coefficients calculated using the equilibrium diffusion coefficients measured during diffusion experiments. In general, atomic transport kinetic measurements during growth and without growth are performed using different types of samples for experimental reasons. In this paper, we discuss the possible use of ultrahigh vacuum in situ Auger electron spectroscopy in order to measure the effective diffusion coefficient during growth, as well as the equilibrium self-diffusion coefficients, in the same samples, in the same experimental conditions. The first results on the Pd-Si system show that atomic transport during Pd2Si growth is several orders of magnitude faster than at equilibrium without interfacial reaction.
Diffusion Controlled Grain Boundary and Triple Junction Wetting in Polycrystalline Solid Metal
Authors: Apyhtina Irina , Kovaleva Kseniia , Novikov Alexander , Orelkina Darya , Petelin Alexander , Yakushko Egor
Published: May 2015

Grain boundary liquid grooving process takes place during the contact of solid phase with the melt. The liquid bismuth network formation along grain boundaries (GBs) and triple junctions (TJs) was investigated in copper polycrystalline samples. The in situ experimental observation technique of Bi penetration through the Cu plate was used. The temperature dependencies of GB and TJ effective penetration depths were determined. The effect of the GB and TJ diffusion on the liquid channels growth mechanism was discussed.
Ni Grain Boundary Diffusion in Cu-Co Alloys
Authors: Rodin Alexey O. , Khairullin Ainur
Published: May 2015

The influence of Co as an alloying element on grain boundary diffusion (GBD) in Cu attracts particular interest due to anomalous GBD of Co in Cu. Ni as a neutral to Co and Cu element was chosen for GBD study. The triple products of Ni GBD in Cu and Cu-Co alloys (with concentration up to 2.9 wt. %) were determined in temperature range 500 – 700 °C by X-ray microprobe analysis. It was shown, that in spite of some scattering the triple product does not depend on Co concentration at all temperatures of experiments. From the obtained results it follows that Co does not change the GB structure.
Ga Penetration along the Grain Boundaries of Aluminum Alloys
Authors: Kovaleva Kseniia , Karpushkina Anastasiia , Litvinenko Gleb , Popova Tatiana , Rodin Alexey O.
Published: May 2015

The Ga penetration process along grain boundaries of Al-based alloys while they are in contact with Ga containing aqueous solution was studied. It was shown that exposure in the solution at room temperature leads to the liquid Ga penetration process, which started with 3 minutes delay. The penetration rate for Al-4.7 % Zn (13 μm/s) is two times less than penetration rate in pure Al. As for Al-Cu alloys it was shown that penetration process occurs only for the alloys with 1.6 % Cu and less, but for larger value of Cu concentration Ga did not penetrate in Al. Comparison of the effect with pure Ga spreading over the alloys surface showed that the absence of penetration connected with absence of wetting.
MD Simulation of Ionic Crystal under Strong Gravitational Field
Authors: Kinoshita Takahiro , Kawakami Takashi , Kawamura Katsuyuki , Mashimo Tsutomo
Published: May 2015

Molecular dynamics (MD) simulations were performed to investigate unique crystalline states of typical ionic crystal at condition of a strong gravitational field (one million G). The simulation results showed that lattice vibration spectra of anion and cation along the gravity direction were different from the spectra along normal directions of the gravity. It is also shown that the shapes of spectra along the gravity are obviously different from the others along normal directions of the gravity. In addition, the peaks of spectra along the gravity were shifted. The simulation results showed that anisotropic lattice vibration spectra were induced by strong gravitational field, and it is insisted that the unique crystalline states and physical properties are induced by strong gravitational field.
Magneto-Diffusional Effect in Ferromagnets in the Constant and Pulsed Magnetic Fields
Authors: Pokoev A.V. , Fedotov A.A.
Published: May 2015

A brief review of experimental data on the effect exerted by both constant and pulse magnetic field upon the heterodiffusion in powders, polycrystalline and monocrystalline ferromagnetic metals and alloys is presented in the paper in order to analyze regularities and mechanisms of the initiation of numerous phenomena covered by the single term “magneto-diffusion effect”. The most probable mechanisms of the magnetic field influence on the diffusion processes are analyzed.
Depletion of Manganese in the Surface Layers of Fe-Mn-Si Shape Memory Alloys by Annealing
Authors: Onuki Yusuke , Fujieda Shun , Shinoda Kozo , Ohtani Hiroshi , Maruyama Tadakatsu , Suzuki Shigeru
Published: May 2015

X-ray diffraction (XRD) and electron microprobe microanalysis (EPMA) were used for characterizing the structure and composition of surface layers formed on austenitic Fe-Mn-Si shape memory alloys under vacuum. The XRD results demonstrated that during annealing, face centered cubic austenite is transformed to hexagonal close packed martensite on the alloy surface. The EMPA results revealed that manganese in the surface layer was depleted during annealing. Further, this analysis determined that the thickness of the surface layer of the alloy annealed at 1173 K for 1 h was approximately 20 μm and that value is consistent with the depth detected by XRD. The compositional changes of the surface layers such as manganese depletion by annealing were discussed based on the ternary Fe-Mn-Si phase diagram. Although the formation of body centered cubic ferrite is detrimental to shape memory alloys, the amount of manganese was also observed to change during processing and strongly influence the stability of the shape memory alloys.
Effects of Compression Tests on Point Defects in Pure Ni and Ni-16wt%Cr Model Alloys
Authors: Ganster Patrick , Borbely A. , Barnier V. , Desgardin Pierre , Barthe Marie-France , Soisson Frederic , Nastar Maylise , Martinelli Laure , Desgranges Clara
Published: May 2015

On Ni and Ni-16wt%.Cr model-alloys compressed at 30 % and 60 % deformation, point-defects and dislocations concentrations are respectively characterized by positron annihilation spectroscopy and x-ray diffraction analysis. The positron results show that only mono-vacancies are formed during compressive test The X-ray results allows us to quantify the dislocation concentration in the systems. Saturation of defect densities is observed in measurements for these high deformation rates. In support to the experimental work, an homogeneous kinetic model is used to characterize point-defect – dislocation interactions to estimate the kinetics of vacancy restoration to equilibrium concentration.
Investigation of Grain-Boundary Diffusion of Co in Mo by Radiotracer Method and Mössbauer Spectroscopy
Authors: Popov Vladimir V. , Sergeev A.V. , Istomina A.Yu.
Published: May 2015

Grain boundary diffusion of Co in Mo has been studied by radiotracer analysis and emission Mössbauer spectroscopy. The experimental results are treated based on the specified Fisher model. The mechanism of grain boundary diffusion of Co in Mo and temperature dependences of segregation factor and grain boundary diffusivity have been determined.
Atomistic Model for Ge Condensation under SiGe Oxidation
Authors: Ganster Patrick , Saul Andrès , Treglia Guy
Published: May 2015

Oxidation of a dilute Si(Ge) alloy is modeled using an original protocol based on molecular dynamicssimulation and rules for the oxygen insertions. These rules, deduced from ab-initio calculations,favor the formation of SiO2 against GeO2 oxide which leads to segregation of Ge atoms into the alloyduring the oxidation front advance. Ge condensation is then observed close to the SiO2/Ge interfacedue to the strain induced by oxidation in this region. From the analysis of the simulations process, wepropose a one-dimensional description of Ge condensation which reproduces the evolution of the Geconcentration during oxidation of the SiGe alloy.
Calculation of Kirkendall Plane Position in Single and Multiphase Systems
Authors: Wierzba Bartek , Skibiński Wojciech
Published: May 2015

In this paper three methods for calculating Kirkendall plane position after diffusion process are described. Bifurcation of K-plane is discussed. Kirkendall planes shift is simulated in hypothetical binary system where solid solution occur and binary system, where two interphases occur. Kirkendall plane shift was estimated by marker conservation method, which is described. It was shown that bifurcation of Kirkendall plane can occur in multiphase systems.
Lithium Transport through Thin Silicon Layers: On the Origin of Bragg Peaks in Neutron Reflectometry Experiments
Authors: Hüger Erwin , Dörrer Lars , Stahn Jochen , Geue Thomas , Schmidt Harald
Published: May 2015

Lithium transport through ultrathin silicon layers can be measured non-destructively by neutron reflectometry (NR) using a multilayer composed of silicon layers embedded between solid state Li reservoirs. An established model system is a multilayer with a repetition of five [Si / natLiNbO3 / Si / 6LiNbO3] units. Two types of Bragg peaks are detectable in reflectivity patterns. These Bragg peaks result from the interference of neutrons reflected at periodic interfaces. One type of Bragg peak originates from the periodicity of the LiNbO3/Si chemical contrast (first order peak), while the other Bragg peak results from a superstructure with double periodicity. This superstructure may arise from 6Li/7Li isotope contrast or alternatively from periodic thickness variations, as shown by simulations based on the Parratt algorithm. The intention of the present paper was to elucidate the origin of the second Bragg peak. Experiments done by Secondary Ion Mass Spectrometry (SIMS) isotope sensitive depth profiling showed in a direct way that annealing at 360 °C destroys indeed the 6Li/7Li contrast, whereas the LiNbO3/Si chemical contrast remains unchanged. This evidences that the experimentally observed decrease of the second Bragg peak in the reflectivity pattern during annealing is a measure for Li transport through the Si layer.
Lithium Diffusion in Li-Rich and Li-Poor Amorphous Lithium Niobate
Authors: Rahn Johanna , Ruprecht Benjamin , Heitjans Paul , Schmidt Harald
Published: May 2015

The diffusion of lithium in amorphous lithium niobate layers is studied as a function of temperature between 293 and 423 K. About 800 nm thick amorphous 7LiNbO3 layers were deposited on sapphire substrates by ion-beam sputtering. As a tracer source about 20 nm thin 6LiNbO3 layers were sputtered on top. Isotope depth profile analysis is done by secondary ion mass spectrometry. Compared are amorphous samples which show a ratio of Li : Nb < 1 (Li-poor) and of Li : Nb > 1 (Li-rich) close to the stoichiometric composition of Li : Nb = 1 for crystalline LiNbO3. The results reveal that the diffusivities of both types of samples obey the Arrhenius law with an activation enthalpy of 0.70 eV and 0.83 eV, respectively. The diffusivities of the sample containing a higher amount of Li are lower by a factor of about two to ten. This demonstrates that variation of the Li content in amorphous samples over the stability range of the crystalline LiNbO3 phase has only a modest influence on diffusivities and activation enthalpies.
Electrochemistry of Symmetrical Ion Channel: Three-Dimensional Nernst-Planck-Poisson Model
Authors: Bożek Bogusław , Leszczyński Henryk , Tkacz-Śmiech Katarzyna , Danielewski Marek
Published: May 2015

The paper provides a physical description of ionic transport through the rigid symmetrical channel. A three-dimensional mathematical model, in which the ionic transport is treated as the electrodiffusion of ions, is presented. The model bases on the solution of the 3D Nernst-Planck-Poisson system for cylindrical geometry. The total flux includes drift (convection) and diffusion terms. It allows simulating the transport characteristics at the steady-state and time evolution of the system. The numerical solutions of the coupled differential diffusion equation system are obtained by finite element method. Examples are presented in which the flow characteristics at the stationary state and during time evolution are compared. It is shown that the stationary state is achieved after about 2×10 -8 s since the process beginning. Various initial conditions (channel charging and dimensions) are considered as the key parameters controlling the selectivity of the channel. The model allows determining the flow characteristic, calculating the local concentration and potential across the channel. The model can be extended to simulate transport in polymer membranes and nanopores which might be useful in designing biosensors and nanodevices.
Kinetics of Void Growth in Cubic Metals: Theory and Simulation
Authors: Mikheev Alexander , Nazarov Andrei , Ershova Irina , Zaluzhnyi Alexander
Published: May 2015

We examine the effect of elastic stresses induced by growing voids on the diffusion vacancy fluxes using newly derived equations. One of the main goals of our work is to obtain a kinetic equation for the growth rate of voids in cubic metals. The diffusion equation for vacancies, in which the influence of elastic stress near the void on the flux is taken into account, is linearized and solved. Then after mathematical transformations that are similar to Lifshitz - Slyozov theory, kinetic equations for the growth rate of the voids in fcc and bcc metals are obtained. The kinetic equations contain additional terms due to developed strain. This feature distinguishes the present equation from known ones and changes the kinetic of void growth. The functional dependence on strain is determined by coefficients, which characterize the strain influence on diffusion (SID coefficients). These coefficients are very sensitive to the atomic structure in the nearest vicinity of the saddle-point configuration. We have built an advanced model to evaluate them. SID coefficient simulation is the next step of this work. Using the kinetic equations and the SID coefficients, we calculate the void growth rate in cubic metals under different conditions.
Chitosan Nanocarriers Loading Anti-Tumor Drugs
Authors: Wu Ji Wei , Song Xin Feng , Sun Han Wen , Zhang Yan Cong , Gu Xiang Ling , Dong Ping Xuan , Cui Shu Qin , Fu Chun Hua
Published: May 2015

Chitosan is a kind of natural polymer commonly applied for nanomaterials, which is affluent in nature with favorable biodegradability and biocompatibility and free of toxicity or odor. In clinic it can be used as a drug carrier for the treatment of cancer, and also it is a kind of new pharmaceutical excipient. To prepare chitosan nanomaterial, various method are used, such as ionic crosslinking, covalent crosslinking, precipitation, free radical polymerization, reverse micelle, spray drying, and self-assembly. Furthermore, plenty of anti-tumor drugs, including adriamycin, epirubicin, taxol, 5-fluorouracil, norcantharidin, folic acid, and so on, are also attempted to load on these chitosan nanocarriers. In addition, the mechanism for those nanocarriers carrying anti-tumor drugs acting on tumor cell were explored, and the formulation mainly include electric charge adhesion effect, suppressing the proliferation of tumor cells, adjusting or enhancing immune ability of the body and inducing apoptosis. This paper compared the characteristics of different preparation methods on chitosan as a nanodrug carrier, summarized the types of packaged drugs, analyzed the mechanism of the chitosan as nanodrug carriers. It can provide valuable reference for researchers' further work.
Origins of Height Distribution within Carbon Nanotube Arrays
Authors: Li Yang , Li Ru , Zhang Hao , Luo Min , Zhang Yong Yi , Dai Zhen Dong
Published: May 2015

We investigated the phenomenon of non-uniform height distribution within CVD-grown carbon nanotube (CNT) arrays. This phenomenon is related to the activity of the catalyst which is affected by the deposition of the carbon source and the subsequent formation of pyrolysis products on the catalyst. We developed a model that considers the effects of deposition of the carbon source as well as the fact that the pyrolysis products also accumulate at the edges of CNT arrays. This model also illustrates that carbon source deposition results in moderate growth over large areas, whereas the pyrolysis products hinder growth significantly over small areas. Together, the two have a competitive effect on CNT growth and bring about the height distribution feature.
Green Electrospinning and Crosslinking of Polyvinyl Alcohol/Citric Acid
Authors: Shi Jing Jing , Yang En Long
Published: May 2015

The present study reports green electrospinning of polyvinyl alcohol (PVA) / citric acid nanoﬁber membranes, and the membranes were then crosslinked by heat treatment. The electric conductivity of the PVA aqueous solution increases rapidly and the growth slows down along with the increase of citric acid content. The viscosity of 13 wt% PVA aqueous solutions with citric acid had a small increase and remained stable in one week, which was suitable for electrospinning fibers. Porous, interconnected nonwoven nanofiber membranes were electrospun from a thoroughly mixing of PVA/ citric acid aqueous solution. The membranes were then heat treated at 140 °C for 2 h. The postelectrospinning crosslinked nanoﬁber membranes were insoluble in water, while the non-crosslinked electrospun nanoﬁber membranes dissolved instantaneously. FT-IR spectrum, X-ray diffraction, and DSC thermograms reveal that crosslinking of PVA nanoﬁber membranes occurred through esterfication reaction during heat treatment.
Modeling of Quasi-Ballistic Silicon Cylindrical Gate-all-Around MOSFETs
Authors: Vimala P.
Published: May 2015

A compact model for the quasi-ballistic cylindrical gate-all-around MOSFET was developed by supplementing the ballistic framework previously disclosed by us with an original energy quantization model. The ballistic mobility is calculated for both degenerate and nondegenerate conditions under collision-free transport. The conventional device electric current showed a remarkable decrease compared with the quasi-ballistic current. The results so obtained have been compared with those obtained from Sentarus device simulator and are found to be in good agreement.
Nanomorphology of Aluminum Oxide Layer after Argon Ion Bombardment
Authors: Ashkhotov Oleg , Ashkhotova Irina
Published: May 2015

Auger electron spectroscopy (AES) and electron energy loss spectroscopy (EELS) studied the interaction of argon ions with a natural oxide layer of polycrystalline aluminum. It was found that the bombardment of argon ions with an energy lower sputtering threshold Al2O3leads to accumulation of ions bombarding the interstitial voids in the surface, thereby forming a solid solution of atoms of the target, the argon ions and nitrogen ion beam, the captured residual gas from the chamber of the spectrometer.
Al2O3 Nanopowders, a Suitable Compound for Active Control of Biofouling
Authors: Mehregan Mohsen , Soltaninejad Hossein , Toluei Nia Behnaz , Zare-Zardini Hadi , Zare-Shehneh Masoud , Ebrahimi Leila
Published: May 2015

The formation of biofilm (Biofouling) in different surface is the great concern in types of fields, especially in medical and health system as well as in membrane technology. The present study deals with the synthesis and characterization of Al2O3 nanopowders with antibacterial activity which can be a potentially utilized material for biocompatible implants. Nanostructure was synthesized based on sol-gel method and then, crystallite size, and microstructural and morphological characterization of nanostructure were determined by X-ray diffraction, electron-microscopic techniques - scanning electron microscopy (SEM) and transmission electron microscopy (TEM). According to X-ray diffraction, the value of particle size for Al2O3 nanopowders is 20.85 nm. In the following, the antibacterial activity of Al2O3 nanoparticles was assessed on three gram positive and three gram negative bacteria by radial diffusion assay and measurement of minimum inhibitory concentration (MIC). The toxicity of Al2O3 nanopowders on blood cells was also assessed. The results showed that this nanostructure has potent antibacterial activity against gram positive and gram negative bacteria. The synthesized Al2O3 nanopowders showed the antimicrobial activity against antibiotic resistant bacterium, Staphylococcus aureus. Significant antibacterial activity of this nanostructure was seen to have a greatest effect on Bacillus cereus with the MIC value of 9.2 μg/ml; while, among bacterial strains, Salmonellatyphimurium was investigated to be the most resistant one with the MIC of 35.6 μg/ml. Al2O3 nanopowders showed no toxicity on blood cells. according to acquired data in this study, Al2O3 nanopowders may be a good material for inhibition of biofilm formation.
Optimization of Gold Nanoparticle Biosynthesis by Escherichia coli DH5α and its Conjugation with Gentamicin
Authors: Motamedi Hossein , Khademi Mazdeh Samaneh , Akbarzadeh Khiavi Azim , Mehrabi Mohammad Reza
Published: May 2015

Metal nanoparticles are one option for targeted drug delivery. In order to increase antibiotic efficiency and decrease its side effects, antibiotic conjugated nanoparticles have been known as a suitable approach. The aim of this study was optimization of gold nanoparticle biosynthesis byEscherichia coliDH5α and its conjugation with gentamicin. For this purpose gold nanoparticles were biosynthesized from HAuCl4and confirmed by Uv/ Vis, XRD, DLS and SEM. Then the effects of different parameters on optimum conditions for gold nanoparticles production were investigated. The MIC and MBC of gentamicin and its conjugate were investigated againstE. coli,Clostridium perfringensandClostridium botulinum. The results revealed that among different treatments, centrifuge (10000 rpm, 10 min) and sonication are the optimum conditions for gold nanoparticle production with less than 10 nm sizes. Filtration was also the best method for purifying nanoparticles. The conjugated nanoparticles significantly reduced the MIC of gentamicin againstE. coliand also overcame the natural resistance of tested anaerobic bacteria. In conclusion, the optimized method is an effective, inexpensive and environmental friendly method for biosynthesis of gold nanoparticles. Overcoming natural resistance of anaerobic bacteria using antibiotic conjugates with nanoparticles provides hopes for further experiments and in vivo studies.
Species-Specific Differences in the Expression and Regulation of α4β7 Integrin in Various Nonhuman Primates
Authors: Byrareddy Siddappa N. , Sidell Neil , Arthos James , Cicala Claudia , Zhao Chunxia , Little Dawn M. , Dunbar Paul , Yang Gui X. , Pierzchalski Keely , Kane Maureen A. , Mayne Ann E. , Song Byeongwoon , Soares Marcelo A. , Villinger Francois , Fauci Anthony S. , Ansari Aftab A.
Published: May 2015

Among nonhuman primates, SIV-infected Asian pigtailed macaques (PM) are relatively more susceptible to infection and disease progression than SIV-infected rhesus macaques (RM). In addition, SIV-infected African natural hosts such as the sooty mangabeys (SM) are resistant to disease. The mechanisms associated with such species-related variable clinical outcomes remain ill-defined but hold the potential to provide insights into the underlying mechanisms surrounding HIV pathogenesis. Recent findings indicate that the expression of the heterodimeric gut homing integrin α4β7 can influence both susceptibility and disease progression in RM. It was reasoned that differences in the frequencies/surface densities of α4β7-expressing lymphocytes might contribute to the differences in the clinical outcome of SIV infection among NHPs. In this article, we report that CD4+ T cells from PM constitutively express significantly higher levels of α4β7 than RM or SM. Retinoic acid, a key regulator of α4β7 expression, was paradoxically found at higher levels in the plasma of SM versus RM or PM. We also observed pairing of β7 with αE (αEβ7) on CD4+ T cells in the peripheral blood of SM, but not PM or RM. Finally, the differential mean density of expression of α4β7 in RM versus SM versus PM was predominantly dictated by species-specific sequence differences at the level of the β7 promoters, as determined by in vitro reporter/promoter construct transfection studies. We propose that differences in the regulation and expression of α4β7 may explain, in part, the differences in susceptibility and SIV disease progression in these NHP models.
Research Questionnaire on Perception of Seafarers about Oral Hygiene and Oral Dietary Habits
Authors: Mahdi Syed Sarosh , Mancini Maurizio , Sibilio Fabio , Amenta Francesco
Published: May 2015

Objectives

Dental problems are among the main concerns of seafarers and a relevant cause of medical consultations aboard international vessels. Seafarers may neglect their oral hygiene during long voyages and are known for their excessive intake of beverages or unhealthy food which contains copious amounts of fermentable carbohydrates and sugars, which are prime risk factors of dental caries. Majority of studies done on oral health status of seafarers are dated. This paper presents a questionnaire developed by Centro Internazionale Radio Medico (CIRM), the Italian Telemedical Maritime Assistance Service (TMAS) to investigate the oral hygiene condition of seafarers and to assess their awareness and sensitivity on this pertinent health problem.

Methodology

A questionnaire including 26 questions covering general information about the subject, including denture status, smoking, drinking and eating habits, general appearance of gingiva, oral muscosa and lips was developed. The research questionnaire was created to assess the oral health situation of Seafarers on board various ships around the world. The questionnaire was forwarded to different ships using the platform of Centro Internationzionale Radio Medico in Rome. Twenty-six questions on various oral hygiene indicators were part of the questionnaire. Captains of the ship were requested to summarize the results on a summary sheet provided by CIRM. CIRM started out sending questionnaire at the end of June 6 and the project concluded in October.

Results

In the 3 months of the survey, CIRM assisted 1,198 ships. All these ships were requested to take part in the research survey. CIRM received positive response from 65 vessels. The rate of return was 5.4%. Two thousand and sixty seamen filled the questionnaire. No difficulty was reported by ship's captains in summarizing the results of the survey.

Conclusion

The findings of the research will be presented in an original research article after completion of data analysis. Captains of the ships who took part in the project were awarded certificates of appreciation for their effort. The results of the project will be useful in future policy initiatives regarding oral healthcare of seafarers.

How to cite this article

Mahdi SS, Mancini M, Sibilio F, Amenta F. Research Questionnaire on Perception of Seafarers about Oral Hygiene and Oral Dietary Habits. World J Dent 2015;6(1):1-4.
An in vitro Evaluation of Antibacterial Activity of Curcumin against Aggregatibacter actinomycetemcomitans
Authors: Bhat Kishore , Savita Abdulpur Mallikarjun , Dawra Charu
Published: May 2015

Introduction

Development of bacterial resistance to the available antibiotics and increasing popularity of traditional medicine has led researchers to investigate the antibacterial compounds in plants. In this context, curcumin has been shown to have a range of beneficial properties, like antimicrobial and anti-inflammatory properties, which might be favorable for the treatment of inflammatory diseases like periodontitis.

Aims and objectives

The primary objective of this study was to evaluate the antibacterial potential of curcumin against Aggregatibacter actinomycetemcomitans (ATCC 29523).

Materials and methods

The bacterial strains of A. actinomycetemcomitans from the stock were revived and transferred to sterile brain heart infusion (BHI) broth. Minimum inhibitory concentration (MIC) was determined by serial broth dilution of curcumin. The last tube with clear supernatant was considered to be without any growth and taken as MIC value.

Results

The mean MIC value of curcumin against A. actinomycetemcomitans (ATCC 29523) was reported to be 0.2 μg/ml.

Conclusion

Thus, it can be concluded that the pleiotropic activities of curcumin derived from its complex chemistry and its ability to influence and control the multiple signaling pathways, makes it a suitable and safer option for the treatment of periodontal diseases.

How to cite this article

Savita AM, Dawra C, Bhat K. An in vitro Evaluation of Antibacterial Activity of Curcumin against Aggregatibacter actinomycetemcomitans. World J Dent 2015;6(1):16-19.
Comparative Study of Acrylic Color and India Ink for Their Use as a Surgical Margin Inks in Oral Squamous Cell Carcinoma
Authors: Patil Anuprita , Anand Rahul , Mahajan Pratiksha
Published: May 2015

Objective

To compare acrylic color and India ink for their use as a surgical margin. Since, acrylic paints are available in multiple colors, they can be used to mark different surgical margins with different specific colors.

Materials and methods

The study was carried out on 30 surgically excised and formalin fixed oral squamous cell carcinoma (OSCC) specimens. Four surgical margins of each 15 specimens were marked with India ink and the remaining were marked with acrylic colors. The grossed specimens were then processed using routine histopathology technique. The 4 mm sections of tissue block were cut using microtome and sections were stained with hematoxylin and eosin stain. Various macroscopic and microscopic parameters were used to study the suitability of acrylic color as surgical ink.

Results

Three different technicians found equal ease of application for acrylic color and India ink. The drying time for acrylic color (1.30 ± 0.009 minutes) was significantly less than India ink (2.30 ± 0.05 minutes). Out of total 60 blocks made for acrylic colors, 52 (86.66%) displayed clear visibility on paraffin blocks (93.33%). In contrast, out of 60 blocks made for India ink, only 34 showed faint visibility on paraffin blocks (56.66%). All acrylic colors were visible very clearly and uninterruptedly under the microscope, while three (5%) surgical margins stained with India ink were interrupted. With the acrylic colors, no contamination or staining of other tissues, processing fluids and solutions were reported. However, with India ink, three (5%) samples reported contamination in alcohol and xylene. There was no interference with the microscopic interpretation of nuclear and cellular details for both acrylic color and India ink whatsoever.

Conclusion

Acrylic colors are more suitable as surgical ink over India ink because of its availability in different colors, ease of application, faster drying time, and no contamination with processing fluids, easy availability and excellent visibility on paraffin blocks and under microscope. Moreover, if needed, painting with multiple colors could also help in reassessment of surgical margins of the gross specimen in the future.

How to cite this article

Sarode SC, Sarode GS, Patil S, Mahajan P, Anand R, Patil A. Comparative Study of Acrylic Color and India Ink for Their Use as a Surgical Margin Inks in Oral Squamous Cell Carcinoma. World J Dent 2015;6(1):26-30.
Ectodermal Dysplasia in a 6 Years Old: A Clinical Challenge
Authors: Bansal Aayushi , Bharadwaj Bindu , Vashishth Abhishek
Published: May 2015

Ectodermal dysplasia depicts a group of inherited disorder in which two or more than two ectodermally derived structures fail to develop perfectly. Intervention at an early stage not only improves patient's appearance but also minimize the associated psychological and emotional problem in such children. This paper presents a case of a 6 years old girl who was referred to our department with complain of absence of multiple teeth for which oral rehabilitation was done.

How to cite this article

Bharadwaj B, Bansal A, Vashishth A, Sharma S. Ectodermal Dysplasia in a 6 Years Old: A Clinical Challenge. World J Dent 2015;6(1):58-60.
Respuestas morfogénicas de tres explantes de Lupinus montanus (hbk) cultivados in vitro
Authors: Ramírez-González Gabriel , Rodríguez-de la O José L. , Arreola-Ávila Jesús G. , Álvarez-Moctezuma José G.
Published: May 2015

El necrosamiento y la respuesta morfogénica de explantes de cotiledón, epicótilo e hipocótilo de plántulas de Lupinus montanus (HBK) germinadas in vitro se evaluaron para establecer las condiciones básicas de micropropagación. El necrosamiento se evaluó en medio MS con 0.40 mg·litro-1 de tiamina, 100 mg·litro-1 de mio-inositol, 3 % de sacarosa y 7 g·litro-1 de agar-agar y distintas dosis de carbón activado (CA) y ácido cítrico. Los tratamientos con CA (50 mg·litro-1 y 100 mg·litro-1) fueron los mejores en el control del necrosamiento (P = 0.001); el cotiledón tuvo mayor nivel de necrosamiento (< 60 %) que el epicótilo e hipocótilo (entre 10 y 30 %). Las respuestas morfogénicas se analizaron en medio MS con 0.40 mg·litro-1 de tiamina, 100 mg·litro-1 de mio-inositol, 3 % de sacarosa, 7 g·litro-1 de agar-agar, 100 mg·litro-1 de CA y cinco combinaciones de AIA (ácido indol acético) y BA (6-benciladenina). Los explantes de hipocótilo y epicótilo mostraron mayor respuesta organogénica (> 70 %) a diferencia del cotiledón, cuya respuesta fue primordialmente callogénica (50 %). El epicótilo cultivado en medio MS con 3.0 μM de AIA y 1.0 μM de BA tuvo el mayor número de brotes (10) y altura (11.4 ± 2.6 cm).
Ozone distributions over southern Lake Michigan: comparisons between ferry-based observations, shoreline-based DOAS observations and model forecasts
Authors: Cleary P. A. , Fuhrman N. , Schulz L. , Schafer J. , Fillingham J. , Bootsma H. , McQueen J. , Tang Y. , Langel T. , McKeen S. , Williams E. J. , Brown S. S.
Published: May 2015

Abstract. Air quality forecast models typically predict large summertime ozone abundances over water relative to land in the Great Lakes region. While each state bordering Lake Michigan has dedicated monitoring systems, offshore measurements have been sparse, mainly executed through specific short-term campaigns. This study examines ozone abundances over Lake Michigan as measured on the Lake Express ferry, by shoreline differential optical absorption spectroscopy (DOAS) observations in southeastern Wisconsin and as predicted by the Community Multiscale Air Quality (CMAQ) model. From 2008 to 2009 measurements of O3, SO2, NO2 and formaldehyde were made in the summertime by DOAS at a shoreline site in Kenosha, WI. From 2008 to 2010 measurements of ambient ozone were conducted on the Lake Express, a high-speed ferry that travels between Milwaukee, WI, and Muskegon, MI, up to six times daily from spring to fall. Ferry ozone observations over Lake Michigan were an average of 3.8 ppb higher than those measured at shoreline in Kenosha, with little dependence on position of the ferry or temperature and with greatest differences during evening and night. Concurrent 1–48 h forecasts from the CMAQ model in the upper Midwestern region surrounding Lake Michigan were compared to ferry ozone measurements, shoreline DOAS measurements and Environmental Protection Agency (EPA) station measurements. The bias of the model O3 forecast was computed and evaluated with respect to ferry-based measurements. Trends in the bias with respect to location and time of day were explored showing non-uniformity in model bias over the lake. Model ozone bias was consistently high over the lake in comparison to land-based measurements, with highest biases for 25–48 h after initialization.
Using self-organising maps to explore ozone profile validation results – SCIAMACHY limb compared to ground-based lidar observations
Authors: van Gijsel J. A. E. , Zurita-Milla R. , Stammes P. , Godin-Beekmann S. , Leblanc T. , Marchand M. , McDermid I. S. , Stebel K. , Steinbrecht W. , Swart D. P. J.
Published: May 2015

Abstract. Traditional validation of atmospheric profiles is based on the intercomparison of two or more data sets in predefined ranges or classes of a given observational characteristic such as latitude or solar zenith angle. In this study we trained a self-organising map (SOM) with a full time series of relative difference profiles of SCIAMACHY limb v5.02 and lidar ozone profiles from seven observation sites. Each individual observation characteristic was then mapped to the obtained SOM to investigate to which degree variation in this characteristic is explanatory for the variation seen in the SOM map. For the studied data sets, altitude-dependent relations for the global data set were found between the difference profiles and studied variables. From the lowest altitude studied (18 km) ascending, the most influencing factors were found to be longitude, followed by solar zenith angle and latitude, sensor age and again solar zenith angle together with the day of the year at the highest altitudes studied here (up to 45 km). After accounting for both latitude and longitude, residual partial correlations with a reduced magnitude are seen for various factors. However, (partial) correlations cannot point out which (combination) of the factors drives the observed differences between the ground-based and satellite ozone profiles as most of the factors are inter-related. Clustering into three classes showed that there are also some local dependencies, with for instance one cluster having a much stronger correlation with the sensor age (days since launch) between 36 and 42 km. The proposed SOM-based approach provides a powerful tool for the exploration of differences between data sets without being limited to a priori defined data subsets.