bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation of Triangular Silver Nanoparticles Using Polyvinyl Pyrrolidone with Different Concentration
Authors: Li Kai , Fu Rao , Gao Qing Ran , Tang Ai Wei , Wang Ying Feng
Published: December 2013

This paper continues our previous work on preparation of triangular silver nanoparticles. The method proceeds with reaction of silver nitrate with hydrazine hydrate in the presence of polyvinyl pyrrolidone in aqueous solution. Effects of the concentration of PVP on the morphologies of Ag NPs were systematically investigated. The obtained Ag NPs were characterized by transmission electron microscopy and UV-visible spectrophotometer. The results showed that, triangular Ag NPs with edge lengths in the range of 50-200 nm were obtained using PVP as protective agent with lower concentration. As the concentration of PVP increased, spherical Ag NPs with their sizes about 6.2 nm were prepared and triangular Ag NPs were not obtained. The formation mechanism of triangular Ag NPs has been studied. Ostwald ripening is the driving force on the conversion of spherical Ag NPs to triangular Ag NPs in the presence of PVP.
Mechanically Driven Alloying and Magnetic Properties in Immiscible Mn80Bi20 Nanocrystalline Powders
Authors: Xu Min , Wang Qun Jiao
Published: December 2013

The paper has described the formation of nanocrystalline Mn80Bi20 powders by mechanical alloying and studied the changes of structure and magnetic properties of the powders during the process of ball milling by using X-ray diffraction and saturation magnetization σs measurements. The solid solubility of bismuth in manganese increases with milling time and tends to a stable value after 80h milling. The σs of Mn80Bi20 increases abruptly with milling time at the early stage and begins to decrease after 15h. At the time of 15h, the σs reaches a maximum, which is about 7Am2/kg. The result shows an interesting information that the antiferromagnetic Mn and the diamagnetic Bi produce ferromagnetic Mn80Bi20 in process of mechanical alloying.
Low Temperature Degradation of Y-TZP Ceramic for Dental Applications
Authors: Wu Zhi Kai , Li Ning , Zhao Wan Qian , Yan Jia Zhen
Published: December 2013

Yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP) ceramic has been recently introduced into prosthetic dentistry for the fabrication of crowns and fixed partial dentures (FPDs). The mechanical properties of Y-TZP are the highest ever reported for the all-ceramic materials. This is favorable for the fabrication of multi-unit posterior bridges and the substantial reduction in core thickness. However, Y-TZP ceramic is susceptible to low temperature degradation (LTD), which is detrimental to the long-time survival and aesthetics of zirconia restorations in vivo. This review summarizes the characterization, mechanisms, and influencing factors of the LTD in dental Y-TZP ceramic. In addition, the recent trend of exploring high aging resistant zirconia-based dental ceramics is discussed.
Controlled Synthesis of Cu2O Sheet-Like Particles by a Simple Solution Method
Authors: Wang Rui Xia , Qian Li Wu , Wang Xin
Published: December 2013

Cuprous oxide sheet-like particles had been synthesized via a wet chemical treatment of CuSO4·5H2O and NaOH in the solution at room temperature for 1 h. The as-prepared Cu2O sheet-like particles were characterized by X-ray powder diffraction (XRD), Field-emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM). Cu2O sheet-like particles was determined by these parameters (the amount of polyvinylpyrrolidone (PVP-K30) and reaction time). The possible formation mechanism for the products has been presented. The photocatalytic properties of the as-synthesized samples show the size/shape-dependent properties and potential applications.
The Optimization of Performance the New Type of Insulation Wall Materials Based on Waste Foam Glasses
Authors: Xiang Yi , Luo Yi Ying , Jiang Hai Bin
Published: December 2013

A new type of insulation wall is developed based on waste foam glasses. Performance tests small particle size (1~10mm) foam glass block with mass ratio of 30%~50% shows that the coefficient of thermal conductivity and compressive strength of insulation block are blow 0.2w/(m.K) and above 3.10MPa, respectively. This indicates a well insulation performance and mechanical property however the density and strength are not good enough. If the large particle size (20~65mm) are used with the mass ratio of 50~80%, the density can be lower than 400kg/m3 and the coefficient of thermal conductivity and compressive strength of insulation block are 0.2w/(m.K) and 0.5MPa, respectively. This indicates a lighter weight and better insulation performance. If the 44.7% construction waste are added to the insulation walls, the compressive strength can be improved more than 90% and meet the requirement of bearing walls.
Nanotip-Induced Ultrahigh Pressure-Sensitive Cement-Based Composite and its Pressure-Sensitive Characteristic Model
Authors: Han Bao Guo , Sun Sheng Wei , Ou Jin Ping
Published: December 2013

A smart composite is fabricated from cement-matrix and spiky spherical nickel powders. The electrical resistivity of such composite decreases 69.00% under uniaxial compression. The gage factor of this composite is higher than 895.45 within the elastic regime. This ultrahigh pressure-sensitivity is attributed to the unique needle-like surface morphology of nickel powers. Comparing to the normal smooth spherical nickel particles, the needle-like features of spiky spherical nickel particles can induce field emission and tunneling effects, which leads to highly sensitive responses to strain. A constitutive model relating the change in electrical resistivity to strain of the composite is built within the elastic regime. This model incorporates the field emission effect and the inter-particle separation change of nickel powders in composite. The model is used to predict the pressure-sensitive characteristic behavior of the composite. The predicted result is compared with the experimental data obtained on the composite, and good agreement is obtained.
Preparation of Straw Superabsorbent Composite Material by Microwave Method
Authors: Yang Lian Wei , Wang Rui Jie
Published: December 2013

By microwave method, a superabsorbent function composite material was prepared by grafting sodium acrylate onto straw flour using potassium persalfate (K2S2O8) and N, N'-methylene bis acrylamide as an initiator and crosslinker, respectively. The effect of various preparation conditions on its water absorbency was investigated. When the straw flour content was 6%, the acrylic acid content was 20.0g, the amount of initiator was 0.4%, the neutralization degree of monomer was 80%, the reaction temperature was 70°C and the amount of crosslinker was 0.05%, the materials absorbency was 1360 times in distilled water and 152 times in 0.9% salt-water at ambient temperature. It had also high water retention. The analyses of SEM indicate that sodium acrylate is grafted on the polysaccharides of straw flour.
Effects of Particle Size on Microstructures and Properties of Si/Al Composites
Authors: Zhai Wei Chen , Zhang Zhao Hui , Wang Fu Chi , Li Shu Kui
Published: December 2013

Si/Al composites with different Si particle sizes were fabricated using spark plasma sintering process for electronic packaging. The density, thermal conductivity, coefficient of thermal expansion and flexural strength of the composites were investigated. Effect of Si particle size on structure and properties of the Si/Al composites were studied. The results showed that the Si/Al composites synthesized by spark plasma sintering were composed of Si and Al. Al was uniformly distributed among the Si phase, leading to a high thermal conductivity (>120 W/m·k). The relative density of the Si/Al composites decreased with increasing Si particle size. Small Si particle size produced small grains, leading to a low coefficient of thermal expansion and a high strength. There is an optimal matching among the thermal conductivity, coefficient of thermal expansion and flexural strength when the Si particle size was 44 um.
Experimental Studies and Computer Simulation of Permeability Determination of Porous SiC Preforms
Authors: Zhu Meng Jian , Li Shun , Zhao Xun , Xiong De Gan
Published: December 2013

Permeability of SiC preform is a key parameter during the pressure infiltration studies of molten metal (Copper and Aluminium alloy) into porous SiC preforms during preparation of SiC particle reinforced metal matrix composites (MMC) with high content of SiC reinforcement. Its characterization could be quite helpful to reveal the defect formation mechanism of the composite productions and further optimize the preparation processes of such composites. The objectives of this study were to assess the pore distribution and determine the permeability of porous SiC preforms. We compared the values of permeability obtained from experimental data, calculation by Carman-Kozeny equation and simulation of micro-models. The results of experiment illustrated that permeability were 0.64 × 10-12 m2 (ε=30%), 1.76 × 10-12 m2 (ε=37%) and 10.20 × 10-12 m2 (ε=44%) respectively, which are quite similar to the value both of calculation and computer simulation. Additionally, results indicate that the permeability substantially affected by porosity and both size and shape of filling particles into SiC preform.
Effect of a New Coupling Agent on Mechanical Properties of Domestic High-Modulus Carbon Fiber/Cyanate Composites
Authors: Chen Wei Qiang , Peng De Qun , Qin Wei
Published: December 2013

To improve the overall performance of the domestic high-modulus carbon fiber/cyanate composites, a macromolecular coupling agent (SCC) based on the raw material styrene, methyl acrylate and γ-methyl (acryloyl) trimethoxysilane was synthesized. It also studies the effect of coupling agent content on the mechanical properties of composites. The results show that the dosage of macromolecular coupling agent with 3%, the performance of the composite materials has been notable improved, its bend strength and interlaminar shear strength are 1100Mpa and 63.5Mpa, which has been raised 6.0% and 16.1%, respectively. SEM micrographs show that the addition of a coupling agent effectively improve the interface compatibility between the resin and fibers in composite.
Effect of t-ZrO2 Content on Grinding Performance of Fused Zirconia Alumina Abrasive
Authors: Liao Zhi Jie , Xiao Mu , Wu Hai Yan , Xia Feng , Chen Ying , Xiao J.Z.
Published: December 2013

Fused zirconia alumina has been broadly applied in abrasive industry due to its excellent strength and toughness. The aim of the present work is to investigate the effect of t-ZrO2content on grinding performance of fused zirconia alumina. Commercial fused alumina zirconia (ZA25) powder was used to fabricate the particle size of 380-830 μm abrasive samples for grinding experiment by pressure granulation and sintering at different temperatures. Phase identification of abrasives sintered at different temperatures was made by X-ray diffractometry and the correlations between t-ZrO2content and grinding performance of abrasive were also tested. The results showed that t-ZrO2content of abrasive decreased with sintering temperature increasing within a range of sintering temperatures from 1375 °C to 1450 °C. Grinding performance of abrasive was enhanced as increasing t-ZrO2phase in abrasive. The better the toughness of abrasive powders, the less shape and size change of abrasive powders during grinding, this is the reason why the high t-ZrO2phase contained fused zirconia alumina abrasive exhibit high grinding performance.
Metamaterials with Zero Phase Delay
Authors: Dong Guo Yan
Published: December 2013

During the early years of research into metamaterials, some interest has shifted towards the realization of materials that exhibit zero or near-zero refractive index. A refractive index of zero implies that light enters a state of quasi-infinite phase velocity and infinite wavelength. Instead of strong resonance mechanism in metamaterials, the physical phenomenon of PhC is based on the special dispersion relations of photonic bands with weak loss. Several different metamaterials to realize zero phase delay are introduced in this paper. Their remarkable properties should have significant technological applications in photon delay lines with zero phase difference, information-processing devices, new optical phase control and measurement techniques.
Electronic Structure Tuning and Interface Charge Transfer in Hybrid Graphene/Titania and Adatom/Graphene/Titania: First Principles Calculations
Authors: Zhang Zhi Ya , Sung Dong Chul , Hong Sukl Yun
Published: December 2013

Firstly, density functional calculation was employed to evaluate the electronic structure of graphene/TiO2(100) composite. The results demonstrated that lattice mismatch between graphene and the titania surface brought about apparent modification to the crystal structure and electronic structure of graphene. Additionally, graphene adsorbed with several different adatoms were combined with the titania surface. The effects of the adatoms on the electronic structure and electron transition characteristic of the complex of adatom/graphene/TiO2(100) were evaluated. The results indicated that the adatoms of B and Al shifted the DOS minimum of graphene to the lower energy side of the Fermi level while N, S, F, Pt and Au caused the opposite effect. The adatoms of Pd, Cr and Mn exhibited no obvious effect on the electron transition characteristic of the composite but effectively introduced midgap states. The results demonstrated that adatom/graphene/titania hybrid composite would exhibit excellent potential for photocatalytic application.
Dielectric Properties of Al2O3 Nanofibers/Epoxy Resin Nanocomposites
Authors: Zhang Yu Xia , Zhou Hong , Fan Yong
Published: December 2013

In this article, Al2O3 nanofibers have been successfully synthesized by hydrothermal process and Al2O3 nanofibers/epoxy nanocomposites were fabricated by incorporating the Al2O3 nanofibers modified by 3-aminopropyl trimethoxysilane (APTMOS). Dielectric spectra of the nanocomposites were investigated. The effects of Al2O3 morphology and concerntration on dielectric spectra of nanocomposites were discussed. The results showed that the dielectric constant increased smoothly as the alumina nanofibers concentration increasing, but it decreased with increasing frequency. While the dielectric loss increased slightly with increasing frequency, however, it still remained at a low level.
Synthesis and Characterization of Luminescent TiO2/Polymer Nanocomposites
Authors: Cui Fang , Yao Tong Jie , Yu Jing , Sun Ke Ning
Published: December 2013

Transparent luminescent TiO2/polymer nanocomposites were obtained through the combined use of copolymerization of a novel titanium ion containing monomer with a liquidsolid reaction. The titanium ions are covalently introduced into polymer chains and transformed into TiO2 nanocrystals directly in the solid-state polymer matrices. That allows the generation of high-quality anatase TiO2 nanocrystals with a narrow size distribution in the polymer matrices. The luminescence of the TiO2 nanocrystals is dominated by band-edge luminescence at room temperature.
The Progress of V2O5/TiO2-Based Catalyst in Hg0 Removal and PCCD/Fs Decomposition
Authors: Gu Dong Liang , Liu Shao Guang , Gu Li Ping , Chen Cheng Wu , Wu Jin Ming , Xu Yu Song
Published: December 2013

The common form of vanadium-based catalyst and characteristics of plate-type catalyst are described in this paper. The catalytic mechanism of vanadium-based catalysts about Hg0-oxidation and De-PCCD/Fs is intensivly analyzed. The influencing factors of V2O5-WO3(MoO3)/TiO2 in mercury removal and PCCD/Fs decomposition are expounded.
Research in Effects of Environmentally-Friendly Carbon Black Masterbatch Powder Rubber
Authors: Wei Xu Ling , Gong Guang Bi , Liang Tao , Wang Rong Min
Published: December 2013

To prepare carbon black masterbatch powder rubber, the process of direct agglomerate powderzation has been used. Then the main factors have been studied, such as the dosage of isolation agent and coagulation agent, pH and water binder ratio of condensed system, environment-friendly antiaging agent, temperature and stirring speed. The results show that the best operational condition is as following: the appropriate dosage of isolation agent is 2.0~3.0, and the dosage of coagulation agent is 12, antiaging agent dosage is 0.3, system PH >7, water binder ratio is between 5:1 and 7:1, temperature is 30~50°C and stirring speed is 500~700 r/min.
Anisotropic Nanostructure ZnO Photoelectrodes for CdS/CdSe Quantum Dot Sensitized Solar Cells
Authors: Tian Jian Jun
Published: December 2013

CdS/CdSe quantum dots co-sensitized solar cells (QDSCs) were prepared by combining the successive ion layer absorption and reaction (SILAR) method and chemical bath deposition (CBD) method for the fabrication of CdS and CdSe quantum dots, respectively. In this work, we designed anisotropic nanostructure ZnO photoelectrodes, such as nanorods/nanosheets and nanorods array, for CdS/CdSe quantum dots co-sensitized solar cells. Our study revealed that the performance of QDSCs could be improved by modifying surface of ZnO to increase the loading of quantum dots and reduce the charge recombination.
A Green Procedure for the Ionic Liquid Catalyzed Oxidation of Benzylic Alcohols to Aldehydes or Ketones in Aqueous Media
Authors: Zhang Guo Feng , Ji Xiu Jie , Cheng Bo Wen , Song Jun , Lu Fei , Fu Ran Ran , Huang Jie Ru , Su Peng He , Gou Xiao Rong , Chen Lu Yang , Liu Chao
Published: December 2013

A green oxidation of benzylic alcohols to the corresponding aldehydes or ketones was achieved in aqueous media using ionic liquid/H2O2/HCl catalytic oxidation system. The procedure is mild, environment-friendly and simple. Ionic liquids can be successfully recovered and reused for the oxidation of the same (different) substance. The directing effect of the ionic liquid is supported by the good selectivities and yields. These reactions demonstrate the catalytic oxidation and phase transfer function of the ionic liquid is stronger than that without ionic liquid.
Study on Performance of Transition Metal-Doped Catalysts for DeNOx at Low-Temperature
Authors: Qiao Jin Shuo , Zhang Cui Ya , Yin Xiao Ju , Sun Ke Ning
Published: December 2013

Mn-Ce based catalysts doped with transition metal were synthesized via a sol-gel method for low-temperature Selective catalytic reduction DeNOx. NOx conversion of these catalysts was evaluated under 100 OC-300 OC. H2-Temperature Programmed Reduction was used to investigate the reduction capability effect on NOx conversion. On this basis, sulfur resistance of catalysts was analyzed and Fourier Transform Infrared (FI-IR) spectra were used to discuss sulfur poisoning mechanism of catalysts. The results indicated that NOx conversion of catalysts was Mn-Ce-W0.03 Mn-Ce-Y0.03 > Mn-Ce-Zr0.03 > Mn-Ce >Mn-Ce-La0.03 > Mn-Ce-Pr0.03.W, Zr, Y elements was doped to improve catalytic activity at low-temperature and enhance anti-sulfur ability of catalysts. Especially, W element can restrain sulfate formation and reduce the channel blocking of the catalyst and Mn-Ce-W0.03 catalyst displays optimal performance of resistance to sulfur poisoning.
Synthesis and Crystal Structure of a Novel Ho(III) Coordination Polymer with Oxalic Acid
Authors: Li Tian Tian , Xia Jun
Published: December 2013

A novel metal-organic frameworks (MOFs), {[Ho (ox)1.5(H2O)3] ·CH3OH·(C2N2H6)0.5}n , has been hydrothermally synthesized and characterized by single-crystal X-ray diffraction, IR analyses, elemental analysis. The complex crystallizes in the monoclinic system with the P21/c space group. The metal ion is nine-coordinate and connected by oxalate to form 2D honeycomb-like structure.
Acoustic Properties of Loose and Consolidated Nonmetal Particles from Waste Printed Circuit Boards
Authors: Sun Zhi Xing , Shen Zhi Gang
Published: December 2013

The aim of this study was to present a new method for resource utilization of nonmetal particles from waste printed circuit boards. Acoustic properties of loose particle mixes and their consolidated composites were investigated. Scanning electron microscopy (SEM) observation shows that the nonmetal particles exhibit high irregular shapes and forms an extensive network of micro-pores in the consolidated composites. The acoustic absorbers made from the nonmetal particles exhibit excellent sound absorption ability in broadband frequency ranges. When the particle size is larger than 0.3 mm, the average absorption coefficients are 0.79 and 0.74 for the loose and consolidated materials in the frequency range from 100 to 6,400 Hz. It was found that the consolidation process did not significantly affect the absorption performance when the particle size is larger than 0.15 mm. All the results show that the reuse of nonmetal particles from WPCB as sound absorbing materials represents a promising way for waste recycling and can also resolve both the environment pollution and the noise pollution problems.
Research on Processing Conditions of CBS Transparent Glass-Ceramics
Authors: Wang Yi Min , Zhang Hong Bo , Su Chun Hui , Wei Qin Lei
Published: December 2013

On the basis of experimental verification, the optimum processing conditions of CaO-B2O3-SiO2 (CBS) system transparent glass-ceramics were obtained. Composition of main raw powders (wt%) was:CaO 38%,SiO2 40%,B2O3 12%.The precursor glass was prepared by melting method and annealed at 560°C for 2h and cooled to room temperature at a speed of 5°C/min.The best nucleating agent is P2O5. The appropriate heat treatment regime to precursor glass was determined to be 2h at 600°C for nucleation and 3h at 780°C for crystallizition.Under this condition,the transmittion of glass-ceramics at the range of visable light is 72% in average and Sm3+ keep good luminescence property doped in this host material.
Preparation and Characterization of the Magnetic Layered Double Hydroxide Fluorescence Composite
Authors: Cao Ju Qin , Dong Li E , Zhang Feng Yuan , Gou Guo Jing
Published: December 2013

A fluorescence composite of magnetic layered double hydroxide (MLDH) and fluorescein (FLU) was synthesized by ion change reaction. The crystal structure and properties of the intercalated compound MLDH-FLU were investigated through XRD, IR, TEM and TG-DSC characterization. Results show that fluorescein is suited for intercalation assembly with MLDH, producing MLDH-FLU composite which could be used as a fluorescence probe to test the cell-transmission efficiency of MLDH delivery system.
Characterization of Luminescent LTCC Composite Materials for White LED Package
Authors: Li Xing Yun , Zhou Ji
Published: December 2013

Luminescent low temperature co-fired ceramic (LTCC) was prepared by sintering powders selected from BaO-TiO2-B2O3-SiO2 system with limited amount of additive (Dy3+). It was found that the optimal sintering temperature was 900°C based on the microstructure and the properties of sintering bodies, and then the major phases of the LTCC were Ba2(TiO)Si2O7 and SiO2. The experimental results indicated that the glass-ceramic possesses good yellow emission under 454nm excitation, excellent dielectric properties: εr= 13.09, tanδ<0.001 at 1 MHz. Thus, this material is supposed to be used as the LTCC substrate material for the application in white LED packaging.
Effect of Surface Passivation on Optical and Electronic Properties of Ultrathin Single-Layer Silicon Nanosheets Compared to Bulk Silicon
Authors: Shi Zhang Sheng , Wang Chong , Pan Tao , Ji Peng Fei , Yang Yu
Published: December 2013

The binding energy, electronic structure and optical properties of ultrathin single-layer silicon nanosheets passivated with H-, H3C-, H2-N and HS-cluster were calculated using density functional theory based on plane-wave ultra-soft pseudopotential respectively. Firstly, the most stable configuration was selected from passivated configurations according to the lowest energy principle after calculating their total energies. Secondly the density of state and the band structure of the different passivated systems were calculated. It was found that different passivation clusters could affect the forbidden band, furthermore the passivated HS-cluster could notably decrease the width of forbidden band through electron transfer. Finally, the light absorption and reflection properties were also investigated. All results were conducive to the development of silicon-based optoelectronic devices.
Double Negative Optical Metamaterial with All-Dielectric Fishnet Structure
Authors: Lan Chu Wen , Fu Xiao Jian , Liu Xiao Ming , Li Bo , Zhou Ji
Published: December 2013

An all-dielectric fishnet metamaterial (DFM) composed of multilayer dielectric structure with periodically patterned holes is proposed to generate left-handed behavior in optical frequency region. Different from the metallic fishnet negative index metamaterial realized by coupling the neighbouring functional layers along the propagation direction, this DFM owes its simultaneous negative permeability and permittivity to the hybrid coupled resonances in the same layer. Based on this configration, a wide-band and polarization-independent negative refraction with maximum figure of merit as large as 13.85 is obtained by a silicon-based DFM at 450 nm wavelength. Simple and easy to fabricate, this concept is believed to provide an alternative route to realize high-performance negative index metamateirals at optical frequencies.
Preparation and Properties of CdSiO3: Mn2+, Er3+ Phosphor
Authors: Qu Xiao Fei , Du Fang Lin , Cao Li Xin
Published: December 2013

CdSiO3: Mn2+, Er3+ long-lasting phosphor was prepared by the conventional high temperature solid-state method. Effects of the concentration of Mn2+ and Er3+ on the luminescent properties of phosphor CdSiO3: Mn2+, Er3+ were investigated by means of photoluminescence (PL) spectra and the afterglow intensity decay curves. It was found that when the Mn2+ and Er3+ dopant-concentrations were 0.2 mol% and 0.8 mol% of Cd2+ ions in CdSiO3, respectively, the luminescence of phosphor prepared had better luminescent property and longer afterglow time. The phosphorescence for it could be seen with the naked eye for more than 60 min in the dark after the removal of the 254 nm UV light. Role of Er3+ co-doped into CdSiO3: Mn2+ matrix was discussed in this paper.
Bond Mechanics and Failure Mode of Conductive Silver Adhesive for Transducer
Authors: Wang Chun Ying , Zhang Rui
Published: December 2013

In this paper, a novel conductive silver adhesive (ECA) for transducer is prepared to bond piezoelectric patch and the aluminum substrate. X-ray photoelectron spectroscopy (XPS) is used to study the fracture elements in order to analyze bond mechanics, fracture morphology is observation by scanning electron microscopy (SEM). The result of test and analysis shows ECA with sliane coupling agent have both physical and chemical bonding and the fracture type is cohesive failure. However the ECA without sliane coupling agent only has physical bonding and fracture type is mixed failure.
Effects of Antiplatelet Drugs on Blood Flow through Stenosed Blood Vessels
Authors: Shah Sapna Ratan
Published: December 2013

Antiplatelet drugs block the formation of blood clots by preventing the clumping of platelets inside arteries, particularly in individuals who have atherosclerosis of their arteries, or are otherwise prone to develop blood clots in their arteries. Atherosclerosis is a slow disease in which arteries become clogged and hardened. Fat, cholesterol, calcium, and other substances form plaque, which builds up in arteries. Hard plaque narrows the passage that blood flows through. That causes arteries to become hard and inflexible. Soft plaque is more likely to break free from the artery wall and cause a blood clot, which can block blood flow to vital organs. In this paper an attempt has been made to investigate the effects of antiplatelet drugs on blood flow and significance of non-Newtonian viscosity through a stenosed artery using Herschel-Bulkely fluid model. Numerical illustration presented at the end of the paper provides the results for the resistance to flow, apparent viscosity and the wall shear stress through their graphical representations.
The Preparation of Silk Fibroin Modified PBT-co-PBS/PEG Composite Films and their Effects on Clinical Human Salivary Epithelial Cells Transplantation
Authors: Zhu Jie , Zhang Yue Ming , Tao Zhi Cheng , Xu Nan Wei , Wang Li Qun , Zhu Xiao Lin
Published: December 2013

We reported the preparation of surface modified poly(butylene terephthalate)-co-poly(butylene succinate)-b-poly(ethylene glycol) (i.e. PBT-co-PBS/PEG) films by three methods: silk fibroin coating, SO2 plasma treatment and silk fibroin anchoring. The obtained composite films were named SF/(PBT-co-PBS/PEG), SO2/(PBT-co-PBS/PEG) and SF/SO2/(PBT-co-PBS/PEG), respectively. Their surface properties were characterized by contact angles, surface energies and XPS. The biocompatibility of the films were further evaluated by the morphology, attachment, proliferation and viability of human salivary epithelial cells (HSG cells). Results revealed that SF/SO2/(PBT-co-PBS/PEG) possessed the high surface free energy (59.67 mJ/m2) and could immobilize a great amount of fibroin (SF surface coverage: 26.39 wt%), which attributed to the formation of such polar groups as hydrosulfide group, sulfonic group, carboxyl and carbonyl ones in the process of SO2 plasma treatment. The cell tests suggested that the silk fibroin anchoring could significantly enhance the biocompatibility of PBT-co-PBS/PEG, which implied the potential application of fibroin modified PBT-co-PBS/PEG for clinical HSG cells transplantation in artificial salivary gland constructs.
Characterization and Dissolution Dynamics of Tricalcium Phosphates in Acidified Solution
Authors: Sader Marcia , Ismério Denisar , Andrade Mônica C. , Soares Gloria D. , Bastos Ivan N. , Platt Gustavo M.
Published: December 2013

Bioceramics used in biomedical applications must exhibit specific behaviors. In scaffolds, for instance, the degradability of bioceramics is important to allow the cell ingrowth. Therefore, the dissolution of calcium phosphates increases the ionic concentrations around the interface implant–bone, favoring a more rapid bone apposition to the graft surface. The dissolution takes place under static or dynamic conditions, but the latter is usually not performed under rigorous hydrodynamic control. In the present work, two bioceramics, β-tricalcium phosphate and β-tricalcium phosphate substituted by magnesium, were produced by pressing and sintering to form disks. They were characterized by XRD, Raman, ICP, SEM, AFM and photometric test. The influence of chemical composition in the dissolution test was conducted through strict control of the hydrodynamic conditions. The disks were rotating in a precise speed, in order to produce a dissolution under the well-controlled mass transfer. Subsequently, the calcium release was evaluated in a simulated infectious environment using pH equals to circa 4. Thus, it was possible to evaluate the fraction of dissolution related to mass transfer or surface reactions for a large rotation speed range. The magnesium added to the bioceramic inhibits the total dissolution when compared to pure tricalcium phosphate, probably related to more dense and less soluble ceramic. Moreover, the mass transfer affects relatively less the magnesium tricalcium phosphate than pure tricalcium phosphate.
Extrusion Benchmark 2013 - Experimental Analysis of Mandrel Deflection, Local Temperature and Pressure in Extrusion Dies
Authors: Selvaggio Alessandro , Kloppenborg Thomas , Schwane Martin , Hölker Ramona , Jäger Andreas , Donati Lorenzo , Tomesani Luca , Tekkaya A. Erman
Published: December 2013

A bridge die was designed for the simultaneous extrusion of two rectangular profiles and used in a strictly monitored aluminum extrusion process. Experimental investigations aimed at the measurement of the mandrel deflection, the local die temperature, and the pressure inside the welding chamber by means of special measurement equipment. AA6082 alloy was used as extrusion material. The influence of the extrusion speed on the aforementioned objectives is reported. The experiments were repeated at least three times under the same conditions in order to achieve a statistical validation of the acquired data. These data are provided as reference for the 2013 edition of the Extrusion Benchmark.
Metallurgical and Engineering Challenges in Magnesium Extrusion
Authors: Misiolek Wojciech Z.
Published: December 2013

AZ 31 Magnesium alloy was extruded under industrial conditions into both a solid shape and a hollow profile. A microstructure analysis of the solid shape revealed a bimodal grain distribution. The FEM process simulation was performed for double hat hollow profile, extruded through an eight-port-hole die using the modified flow stress model from literature. This allowed us to make a prediction of the extrusion process state variables. Additionally, a numerical simulation revealed some shortcomings in terms of a lack of predictive capabilities for extrusion welding. The integrity of the welds was analyzed using metallography techniques. The search for better mechanical properties has propelled alloy development research. Workability evaluations of new Magnesium alloys ZE20, ZE50 and ZE80 containing Zinc and Cerium were performed using compression tests under various temperature and strain rate conditions.
GERMINACIÓN, INFESTACIÓN Y VIABILIDAD EN BELLOTAS DE Quercus polymorpha (Schltdl. & Cham.) TRAS UN AÑO DE ALMACENAMIENTO
Authors: González-Salvatierra Claudia , Badano Ernesto I. , Flores Joel , Rodas Juan P.
Published: December 2013

Los encinos blancos tienen semillas recalcitrantes que se mantienen viables por corto tiempo. Sin embargo, esta información es escasa para encinos mexicanos. Este es el caso de Quercus polymorpha, una especie tolerante a la sequía y ampliamente distribuida en la Sierra Madre Oriental que puede utilizarse en programas de restauración forestal. Las bellotas son colectadas durante la época reproductiva y son almacenadas por varios meses antes de su germinación. Este estudio se enfocó en 1) determinar cuántas semillas se pierden durante el almacenamiento debido a factores fisiológicos relacionados con su viabilidad, 2) cuantificar las semillas que se pierden por otros factores, y 3) evaluar si la estratificación fría puede estimular la germinación de las bellotas. Las bellotas utilizadas fueron almacenadas durante un año. El 70 % de las bellotas estaban parasitadas por insectos antes de su almacenamiento, mientras que el 20 % perdió su viabilidad debido a factores fisiológicos o infestación por hongos. Los ensayos de germinación se llevaron a cabo utilizando sólo bellotas potencialmente viables, las cuales fueron sometidas a tres periodos de estratificación en frío (0, 20 y 50 días). El experimento mostró que las bellotas estratificadas durante 50 días tienen mayores tasas de germinación (64.2 %) que las de 20 (44.8 %) y 0 días (16. 5 %).
MODELOS DINÁMICOS DE CRECIMIENTO PARA RODALES REGULARES Y SU DESAGREGACIÓN PARA LA ESTIMACIÓN DE VOLÚMENES Y BIOMASA
Authors: Gómez-García Esteban
Published: December 2013

En este estudio se describe la metodología para desarrollar un modelo dinámico de crecimiento para rodales regulares y su desagregación para predecir volúmenes según destinos comerciales y la biomasa de árboles individuales (total o por componentes). Como ejemplo se toman los modelos desarrollados para rodales regulares de Betula pubescens Ehrh. y Quercus robur L. en Galicia (noroeste de España). La condición de un rodal se describe por las variables de estado; altura dominante, número de árboles por hectárea y área basal. El desarrollo de funciones de transición en diferencias algebraicas permite proyectar dichas variables a cualquier instante futuro. Un sistema de desagregación permite estimar, a partir de las variables de estado, el número de árboles y la altura media por clase diamétrica. Por último, el volumen y la biomasa se estiman desarrollando funciones de salida, que utilizan los diámetros y alturas estimadas en el proceso de desagregación.
RECONSTRUCCIÓN DE PRECIPITACIÓN INVIERNO-PRIMAVERA CON ANILLOS ANUALES DE Pinus douglasiana EN LA RESERVA DE LA BIOSFERA SIERRA DE MANANTLÁN, JALISCO
Authors: Cerano-Paredes Julián , Méndez-González Jorge , Amaro-Sánchez Abihail , Villanueva-Díaz José , Cervantes-Martínez Rosalinda , Rubio-Camacho Ernesto A.
Published: December 2013

Se reconstruyó la precipitación invierno-primavera de 219 años (1792-2010) de la Reserva de la Biosfera Sierra de Manantlán (RBSM), Jalisco, México, empleando los anillos anuales de Pinus douglasiana (Mtz.) como “proxy”. La sequía de mediados del siglo XX (1941-1963) fue la más severa del periodo estudiado. El índice multivariado de El Niño Oscilación del Sur (ENSO; 1959-2010) y el índice de ancho del anillo de P. douglasiana mostraron correlación significativa (r = 0.4542; P < 0.05) de los meses de enero-junio, con mayor correlación en los meses de enero (r = 0.4337; P < 0.0001) y marzo (r = 0.4310; P < 0.0001). Las teleconexiones de ENSO en la región varían a través del tiempo; de enero a junio, los eventos El Niño están asociados con precipitaciones mayores que el promedio, mientras que los eventos La Niña muestran lo contrario.
RESPUESTAS MORFOGÉNICAS EN LA PROPAGACIÓN in vitro DE NOGAL PECANERO (Carya illinoinensis [Wangenh] K. Koch)
Authors: Ávila-Treviño Jazmín A. , Arreola-Ávila Jesús Guadalupe , Rodríguez-de la O José L. , Trejo-Calzada Ricardo , Valdez-Cepeda Ricardo David , Borja-de la Rosa Amparo
Published: December 2013

Las respuestas embriogénicas y organogénicas en nogal (Carya illinoinensis [Wangenh] K. Koch) se observaron bajo el cultivo in vitro de segmentos de hojas, yemas axilares y embriones cigóticos. El necrosamiento se controló empleando carbón activado (CA: 1 %), polivinilpirrolidona (0.1 %), nitrato de plata (AgNO3: 1 %), ácido cítrico (150 mg·L-1) y ácido ascórbico (100 mg·L- 1), con presencia de luz y en oscuridad. Se utilizó el medio básico de Murashige y Skoog suplementado con 0.40 mg·L-1 de tiamina, 100 mg·L-1 de myo-inositol, 3 % de sacarosa, incorporando 2,4-D para hojas, tidiazurón (TDZ) para embriones, y las combinaciones de benciladenina (BA), kinetina (KIN), ácido naftalenacético (ANA) y ácido indolbutírico (AIB) para yemas axilares. El necrosamiento de tejidos se redujo en 75 % y 83 % adicionando CA y AgNO3, respectivamente. El 33 % y 66 % de los callos embriogénicos se indujeron a partir de hojas, utilizando 1 y 3 mg·L-1 de 2,4-D. La mayor producción de callos (58 %) a partir de embriones se obtuvo con la concentración de 3 mg·L-1 de TDZ. En yemas axilares, la combinación de KIN (3.0 μM), BA (1.0 μM) y AIB (0.3 μM) incrementó el número de hojas y plántulas, y longitud de brotes.
Improving a plot-scale methane emission model and its performance at a Northeastern Siberian tundra site
Authors: Mi Y. , van Huissteden J. , Parmentier F. J. W. , Gallagher A. , Budishchev A. , Berridge C. T. , Dolman A. J.
Published: December 2013

Abstract. In order to better address the feedbacks between climate and wetland methane (CH4) emissions, we tested several mechanistic improvements to the wetland CH4 emission model Peatland-VU with a longer Arctic dataset than any other model: (1) inclusion of an improved hydrological module; (2) incorporation of a gross primary productivity (GPP) module; (3) a more realistic soil-freezing scheme. A long time series of field measurements (2003–2010) from a tundra site in Northeastern Siberia is used to validate the model, and the Generalized Likelihood Uncertainty Estimation (GLUE) methodology is used to test the sensitivity of model parameters. Peatland-VU is able to capture both the annual magnitude and seasonal variations of the CH4 flux, water table position and soil thermal properties. However, detailed daily variations are difficult to evaluate due to data limitation. Improvements due to the inclusion of a GPP module are less than anticipated, although this component is likely to become more important at larger spatial scales because the module can accommodate the variations in vegetation traits better than at plot-scale. Sensitivity experiments suggest that the methane production rate factor, the methane plant oxidation parameter, the reference temperature for temperature dependent decomposition, and the methane plant transport rate factor are the most important parameters affecting the data fit, regardless of vegetation type. Both wet and dry vegetation cover are sensitive to the minimum water table level, in addition to the runoff threshold and open water correction factor and the subsurface water evaporation and evapotranspiration correction factors, respectively. These results shed light on model parameterization and future improvement of CH4 modelling. However, high spatial variability of CH4 emissions within similar vegetation/soil units and data quality prove to impose severe limits on model testing and improvement.
L'autre feminine: De la passivité à l'action
Authors: Garduño Comparán Carlos A.
Published: December 2013

Dans ce texte, la notion du féminin est explorée à travers deux schémas présents dans l'œuvre de Ricœur, celui de l'épopée et celui de la tragédie, symbolisés par les figures de Pénélope et Antigone. Par la suite, on proposera Médée comme un exemple qui s'adapte de manière appropriée à la problématique des études de genre, interprété par rapport aux développements de La Métaphore vive sur la ressemblance et la substitution, et au processus de la mimèsis dans Temps et récit.
Introduction
Authors: Henriques Fernanda
Published: December 2013

Introduction to Vol. 4, no. 1 (2013).
Envision adoption and its impact on water infrastructure
Authors: Nelson Denise
Published: December 2013

The Envision rating system is rapidly gaining acceptance throughout the water industry in North America as well as internationally.
Relatório Anual
Authors: Anjos Sara Gadotti dos
Published: December 2013

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On Voxel-by-voxel Accumulated Dose for Prostate Radiation Therapy using Deformable Image Registration
Authors: Yu Jialu , Hardcastle Nicholas , Jeong Kyoungkeun , Bender Edward T. , Ritter Mark A. , Tomé Wolfgang A.
Published: December 2013

Since delivered dose is rarely the same with planned, we calculated the delivered total dose to ten prostate radiotherapy patients treated with rectal balloons using deformable dose accumulation (DDA) and compared it with the planned dose. The patients were treated with TomoTherapy using two rectal balloon designs: five patients had the Radiadyne balloon (balloon A), and five patients had the EZ-EM balloon (balloon B). Prostate and rectal wall contours were outlined on each pre-treatment MVCT for all patients. Delivered fractional doses were calculated using the MVCT taken immediately prior to delivery. Dose grids were accumulated to the last MVCT using DDA tools in Pinnacle3 TM (v9.100, Philips Radiation Oncology Systems, Fitchburg, USA). Delivered total doses were compared with planned doses using prostate and rectal wall DVHs. The rectal NTCP was calculated based on total delivered and planned doses for all patients using the Lyman model. For 8/10 patients, the rectal wall NTCP calculated using the delivered total dose was less than planned, with seven patients showing a decrease of more than 5% in NTCP. For 2/10 patients studied, the rectal wall NTCP calculated using total delivered dose was 2% higher than planned. This study indicates that for patients receiving hypofractionated radiotherapy for prostate cancer with a rectal balloon, total delivered doses to prostate is similar with planned while delivered dose to rectal walls may be significantly different from planned doses. 8/10 patients show significant correlation between rectal balloon anterior-posterior positions and some VD values.
Small Portable Interchangeable Imager of Fluorescence for Fluorescence Guided Surgery and Research
Authors: Okusanya Olugbenga T. , Madajewski Brian , Segal Erin , Judy Brendan F. , Venegas Ollin G. , Judy Ryan P. , Quatromoni Jon G. , Wang May D. , Nie Shuming , Singhal Sunil
Published: December 2013

Fluorescence guided surgery (FGS) is a developing field of surgical and oncologic research. Practically, FGS has shown useful applications in urologic surgery, benign biliary surgery, colorectal cancer liver metastasis resection, and ovarian cancer debulking. Most notably in in cancer surgery, FGS allows for the clear delineation of cancerous tissue from benign tissue. FGS requires the utilization of a fluorescent contrast agent and an intraoperative fluorescence imaging device (IFID). Currently available IFIDs are expensive, unable to work with multiple fluorophores, and can be cumbersome. This study aims to describe the development and utility of a small, cost-efficient, and interchangeable IFID made from commercially available components. Extensive research was done to design and construct a light-weight, portable, and cost-effective IFID. We researched the capabilities, size, and cost of several camera types and eventually decided on a near-infrared (NIR) charged couple device (CCD) camera for its overall profile. The small portable interchangeable imager of fluorescence (SPIIF) is a “scout” IFID system for FGS. The main components of the SPIIF are a NIR CCD camera with an articulating light filter. These components and a LED light source with an attached heat sink are mounted on a small metal platform. The system is connected to a laptop by a USB 2.0 cable. Pixielink © software on the laptop runs the system by controlling exposure time, gain, and image capture. After developing the system, we evaluated its utility as an IFID. The system weighs less than two pounds and can cover a large area. Due to its small size, it is easily made sterile by covering it with any sterile plastic sheet. To determine the system’s ability to detect fluorescent signal, we used the SPIIF to detect indocyanine green under ex and in-vivo conditions and fluorescein under ex-vivo conditions. We found the SPIIF was able to detect both ICG and fluorescein under different depths of a semi-opaque colloid. Second, we found that a concentration as low as 0.5 g/ml of indocyanine green dissolved in plasma was detectable. Lastly, in a murine and human cancer model, the SPIIF was able to detect indocyanine green signal within tumors and generate a signal-to-background ratio (SBR) of 3.75. This study shows that a low-cost IFID can be made from commercially available parts. Second, this IFID is capable of in and ex-vivo detection of multiple fluorophores without sacrificing its small size or favorable ergonomics.