bluuebunny/crossref_metadata_2025 huggingface dataset:
Immune cell infiltrate differences in pilocytic astrocytoma and glioblastoma: evidence of distinct immunological microenvironments that reflect tumor biology
Authors: Yang Isaac , Han Seunggu J. , Sughrue Michael E. , Tihan Tarik , Parsa Andrew T.
Published: June 2011

Object

The tumor microenvironment in astrocytomas is composed of a variety of cell types, including infiltrative inflammatory cells that are dynamic in nature, potentially reflecting tumor biology. In this paper the authors demonstrate that characterization of the intratumoral inflammatory infiltrate can distinguish high-grade glioblastoma from low-grade pilocytic astrocytoma.

Methods

Tumor specimens from ninety-one patients with either glioblastoma or pilocytic astrocytoma were analyzed at the University of California, San Francisco. A systematic neuropathology analysis was performed. All tissue was collected at the time of the initial surgery prior to adjuvant treatment. Immune cell infiltrate not associated with necrosis or hemorrhage was analyzed on serial 4-μm sections. Analysis was performed for 10 consecutive hpfs and in 3 separate regions (total 30 × 0.237 mm2). Using immunohistochemistry for markers of infiltrating cytotoxic T cells (CD8), natural killer cells (CD56), and macrophages (CD68), the inflammatory infiltrates in these tumors were graded quantitatively and classified based on microanatomical location (perivascular vs intratumoral). Control markers included CD3, CD20, and human leukocyte antigen.

Results

Glioblastomas exhibited significantly higher perivascular (CD8) T-cell infiltration than pilocytic astrocytomas (62% vs 29%, p = 0.0005). Perivascular (49%) and intratumoral (89%; p = 0.004) CD56-positive cells were more commonly associated with glioblastoma. The CD68-positive cells also were more prevalent in the perivascular and intratumoral space in glioblastoma. In the intratumoral space, all glioblastomas exhibited CD68-positive cells compared with 86% of pilocytic astrocytomas (p = 0.0014). Perivascularly, CD68-positive infiltrate was also more prevalent in glioblastoma when compared with pilocytic astrocytoma (97% vs 86%, respectively; p = 0.0003). The CD3-positive, CD20-positive, and human leukocyte antigen-positive infiltrates did not differ between glioblastoma and pilocytic astrocytoma.

Conclusions

This analysis suggests a significantly distinct immune profile in the microenvironment of high-grade glioblastoma versus low-grade pilocytic astrocytoma. This difference in tumor microenvironment may reflect an important difference in the tumor biology of glioblastoma.
The Role of Epidermal Growth Factor Receptor Mutations and Epidermal Growth Factor Receptor-Tyrosine Kinase Inhibitors in the Treatment of Lung Cancer
Authors: Chang Shih-Chieh , Chang Cheng-Yu , Shih Jin-Yuan
Published: June 2011

Lung cancer is the leading cause of cancer-related deaths worldwide. Non-small-cell lung cancer (NSCLC) cases comprise approximately 85% of the lung cancer cases. Before the era of target therapy, platinum-based doublet chemotherapy only led to a median survival of 8–9 months and a one-year survival of 30%–40% in patients with advanced NSCLC. In July 2002, gefitinib, a small-molecule epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI), was approved for the treatment of patients with advanced NSCLC in Japan. After the widespread use of gefitinib in the treatment of NSCLC, there have been many new studies regarding the association between the clinical anticancer efficacy of gefitinib and the somatic EGFR mutation status in patients with NSCLC. This article summarizes the role of EGFR mutations in lung cancer and the use of EGFR antagonists in the treatment of lung cancer and its associated adverse effects.
Effect of Discontinuation of Fluoride Intake from Water and Toothpaste on Urinary Excretion in Young Children
Authors: Martins Carolina C. , Paiva Saul M. , Cury Jaime A.
Published: June 2011

As there is no homeostatic mechanism for maintaining circulating fluoride (F) in the human body, the concentration may decrease and increase again when intake is interrupted and re-started. The present study prospectively evaluated this process in children exposed to F intake from water and toothpaste, using F in urine as a biomarker. Eleven children from Ibiá, Brazil (with sub-optimally fluoridated water supply) aged two to four years who regularly used fluoridated toothpaste (1,100 ppm F) took part in the study. Twenty-four-hour urine was collected at baseline (Day 0, F exposure from water and toothpaste) as well as after the interruption of fluoride intake from water and dentifrice (Days 1 to 28) (F interruption) and after fluoride intake from these sources had been re-established (Days 29 to 34) (F re-exposure). Urinary volume was measured, fluoride concentration was determined and the amount of fluoride excreted was calculated and expressed in mg F/day. Urinary fluoride excretion (UFE) during the periods of fluoride exposure, interruption and re-exposure was analyzed using the Wilcoxon test. Mean UFE was 0.25 mg F/day (SD: 0.15) at baseline, dropped to a mean of 0.14 mg F/day during F interruption (SD: 0.07; range: 0.11 to 0.17 mg F/day) and rose to 0.21 (SD: 0.09) and 0.19 (SD: 0.08) following F re-exposure. The difference between baseline UFE and the period of F interruption was statistically significant (p < 0.05), while the difference between baseline and the period of F re-exposure was non-significant (p > 0.05). The findings suggest that circulating F in the body of young children rapidly decreases in the first 24 hours and again increases very fast after discontinuation and re-exposure of F from water and toothpaste.
Proliferation-Attenuating and Apoptosis-Inducing Effects of Tryptanthrin on Human Chronic Myeloid Leukemia K562 Cell Line in Vitro
Authors: Miao Shan , Shi Xiaopeng , Zhang Hai , Wang Siwang , Sun Jiyuan , Hua Wei , Miao Qing , Zhao Yong , Zhang Caiqin
Published: June 2011

Tryptanthrin, a kind of indole quinazoline alkaloid, has been shown to exhibit anti-microbial, anti-inflammation and anti-tumor effects both in vivo and in vitro. However, its biological activity on human chronic myeloid leukemia cell line K562 is not fully understood. In the present study, we investigated the proliferation-attenuating and apoptosis-inducing effects of tryptanthrin on leukemia K562 cells in vitro and explored the underlying mechanisms. The results showed that tryptanthrin could significantly inhibit K562 cells proliferation in a time- and dose-dependent manner as evidenced by MTT assay and flow cytometry analysis. We also observed pyknosis, chromatin margination and the formation of apoptotic bodies in the presence of tryptanthrin under the electron microscope. Nuclei fragmentation and condensation by Hoechst 33258 staining were detected as well. The amount of apoptotic cells significantly increased whereas the mitochondrial membrane potential decreased dramatically after tryptanthrin exposure. K562 cells in the tryptanthrin treated group exhibited an increase in cytosol cyt-c, Bax and activated caspase-3 expression while a decrease in Bcl-2, mito cyt-c and pro-caspase-3 contents. However, the changes of pro-caspase-3 and activated caspase-3 could be abolished by a pan-caspase inhibitor ZVAD-FMK. These results suggest that tryptanthrin has proliferation-attenuating and apoptosis-inducing effects on K562 cells. The underlying mechanism is probably attributed to the reduction in mitochondria membrane potential, the release of mito cyt-c and pro-caspase-3 activation.
Structural Characterization of Poly-L-lactic Acid (PLLA) and Poly(glycolic acid)(PGA) Oligomers
Authors: Casalini Tommaso , Rossi Filippo , Santoro Marco , Perale Giuseppe
Published: June 2011

Structural characterization of poly-L-lactic acid (PLLA) and poly(glycolic acid) (PGA) oligomers containing three units was carried out with an atomistic approach. Oligomer structures were first optimized through quantum chemical calculations, using density functional theory (DFT); rotational barriers concerning dihedral angles along the chain were then investigated. Diffusion coefficients of L-lactic acid and glycolic acid in pure water were estimated through molecular dynamic (MD) simulations. Monomer structures were obtained with quantum chemical computation in implicit water using DFT method; atomic charges were fitted with Restrained Electrostatic Potentials (RESP) formalism, starting from electrostatic potentials calculated with quantum chemistry. MD simulations were carried out in explicit water, in order to take into account solvent presence
Implementation of the CMOS MEMS Condenser Microphone with Corrugated Metal Diaphragm and Silicon Back-Plate
Authors: Huang Chien-Hsin , Lee Chien-Hsing , Hsieh Tsung-Min , Tsao Li-Chi , Wu Shaoyi , Liou Jhyy-Cheng , Wang Ming-Yi , Chen Li-Che , Yip Ming-Chuen , Fang Weileun
Published: June 2011

This study reports a CMOS-MEMS condenser microphone implemented using the standard thin film stacking of 0.35 μm UMC CMOS 3.3/5.0 V logic process, and followed by post-CMOS micromachining steps without introducing any special materials. The corrugated diaphragm for the microphone is designed and implemented using the metal layer to reduce the influence of thin film residual stresses. Moreover, a silicon substrate is employed to increase the stiffness of the back-plate. Measurements show the sensitivity of microphone is −42 ± 3 dBV/Pa at 1 kHz (the reference sound-level is 94 dB) under 6 V pumping voltage, the frequency response is 100 Hz–10 kHz, and the S/N ratio >55 dB. It also has low power consumption of less than 200 μA, and low distortion of less than 1% (referred to 100 dB).
Aflatoxin Toxicity Reduction in Feed by Enhanced Binding to Surface-Modified Clay Additives
Authors: Jaynes William F. , Zartman Richard E.
Published: June 2011

Animal feeding studies have demonstrated that clay additives, such as bentonites, can bind aflatoxins in ingested feed and reduce or eliminate the toxicity. Bentonite deposits are found throughout the world and mostly consist of expandable smectite minerals, such as montmorillonite. The surfaces of smectite minerals can be treated with organic compounds to create surface-modified clays that more readily bind some contaminants than the untreated clay. Montmorillonites treated with organic cations, such as hexadecyltrimethylammonium (HDTMA) and phenyltrimethylammonium (PTMA), more effectively remove organic contaminants, such as benzene and toluene, from water than untreated clay. Similarly, montmorillonite treated with PTMA (Kd = 24,100) retained more aflatoxin B1 (AfB1) from aqueous corn flour than untreated montmorillonite (Kd = 944). Feed additives that reduced aflatoxin toxicity in animal feeding studies adsorbed more AfB1 from aqueous corn flour than feed additives that were less effective. The organic cations HDTMA and PTMA are considered toxic and would not be suitable for clay additives used in feed or food, but other non-toxic or nutrient compounds can be used to prepare surface-modified clays. Montmorillonite (SWy) treated with choline (Kd = 13,800) and carnitine (Kd = 3960) adsorbed much more AfB1 from aqueous corn flour than the untreated clay (Kd = 944). A choline-treated clay prepared from a reduced-charge, high-charge montmorillonite (Kd = 20,100) adsorbed more AfB1 than the choline-treated high-charge montmorillonite (Kd = 1340) or the untreated montmorillonite (Kd = 293). Surface-modified clay additives prepared using low-charge smectites and nutrient or non-toxic organic compounds might be used to more effectively bind aflatoxins in contaminated feed or food and prevent toxicity.
The Use of Ultrasound to Determine Timing of Pavlik Harness Discontinuation in Treatment of Developmental Dysplasia of the Hip
Authors: Carmichael Kelly D. , Longo Anthony , Yngve David , Hernandez Jose Alberto , Swischuk Leonard
Published: June 2011

The timing of Pavlik harness removal in patients with developmental dysplasia of the hip is typically determined by clinical examination. Ultrasound is considered more sensitive than clinical examination in diagnosis of instability of the hip, but it is not routinely used in cases of developmental dysplasia of the hip, especially when determining the timing of Pavlik harness removal. The purpose of this study is to investigate if ultrasound examination is more effective than clinical examination alone in determining completion of Pavlik harness treatment. Fifty consecutive infants with developmental dysplasia of the hip were given both a clinical examination and dynamic ultrasound examination to determine if Pavlik harness treatment could be discontinued. A pediatric orthopedist conducted the physical examinations. Both a radiologist and a pediatric orthopedist interpreted the ultrasounds. Cost estimates for ultrasound and operative procedures were obtained at our institution and compared. The average age at the time of Pavlik harness placement was 5.3 days, and the average age at the time of ultrasound was 54.3 days. There were 35 females and 15 males and 31 left hips, 4 right hips, and 15 bilateral hips. All 50 patient hips were deemed clinically stable prior to obtaining an ultrasound. The ultrasound interpretations by a radiologist and pediatric orthopedist were in agreement in all cases. In one case, the ultrasound results did not correlate with results of the clinical examination. In that one case, the hip was clinically stable, but dynamic ultrasound revealed that the hip was located, but dislocatable. The Pavlik harness was reapplied to the patient for an additional 42 days. At 1-year follow-up the hip is stable and developing normally as determined by radiographs. The cost comparison revealed that the cost of 50 ultrasounds is less than the cost of a single operative procedure. The use of ultrasound to determine the timing of Pavlik harness cessation is justified from both a financial and a patient outcome perspective in this small study. Larger studies are needed before ultrasound examination used to help determine Pavlik cessation is considered standard of care.
Primary Total Hip Arthroplasty for Displaced Femoral Neck Fracture
Authors: Watson David , Bostrom Mathias , Salvati Eduardo , Walcott-Sapp Sarah , Westrich Geoffrey
Published: June 2011

Total hip arthroplasty (THA) for displaced femoral neck fracture has potential advantages over open reduction/internal fixation and hemiarthroplasty. Thirty-seven patients who underwent THA for displaced femoral neck fractures between June 1993 and June 2005 were evaluated, and the exact head/neck ratios were calculated by the prosthesis manufacturers. The major complication rate was 16.1% (6 of 37) with 5 dislocations (all with surgery prior to 2002) and one nonfatal myocardial infarction. One- and 2-year mortality was 2.7% (1 of 37) and 8.1% (3 of 37), respectively. A smaller head/neck ratio (
P
= .002) in patients who dislocated was observed. The optimal head/neck ratio was ≥2.13. Total hip arthroplasty for displaced femoral neck fracture allows patients to return to most preinjury activities. In order to avoid dislocation, constructs with a larger head/neck ratio should be used.
Synthesis of Colloidal Carbon Spheres by Hydrothermal Carbonization of Glucose at Different Initial pH
Authors: Jiang Guo Hui , Xu Xue Qing , Xu Gang
Published: June 2011

In this paper, carbon spheres with different size distributions are obtained by hydrothermal carbonization of glucose via varying the reaction conditions including concentration of glucose solution, hydrothermal reaction time and the initial pH values of solutions. The initial pH values of glucose solutions play an important role in the size distribution of the carbon spheres. The formation and growth mechanisms of carbon spheres at different initial pH levels are discussed and proposed.
Study on Determination of I-V Curve of Dye-Sensitized Solar Cell
Authors: Tian Han Min , Yu Tao , Zou Zhi Gang
Published: June 2011

Many studies reported that dye-sensitized solar cells have more significant capacitance characteristics than the silicon solar cell. In this study, it was found the capacitance characteristics of dye-sensitized solar cell changes with the imposed bias voltage. The bias voltage is indispensable in the standard measurement for the conversion efficiency of dye-sensitized solar cell. The influence of changed capacitance during the measurement on the conversion efficiency of dye-sensitized solar cells was investigated. The analysis on the EIS spectra and equivalent circuit shows that the capacitance of dye-sensitized solar cells is small and the deviation cell I-V characteristics from the steady-state value is minor when the applied bias is small; while under a condition with a large applied bias, the capacitance characteristics of dye-sensitized solar cell grew rapidly and the I-V characteristics deviated from the steady-state value significantly increased. This phenomenon is helpful for the accurate measurement of the quantum conversion efficiency and photoelectric conversion efficiency of dye-sensitized solar cells.
Thermal Stability of Aluminum Doped Zinc Oxide Thin Films
Authors: Huang Jin Hua , Tan Rui Qin , Li Jia , Zhang Yu Long , Yang Ye , Song Wei Jie
Published: June 2011

Transparent conductive oxides are key electrode materials for thin film solar cells. Aluminum doped zinc oxide has become one of the most promising transparent conductive oxide (TCO) materials because of its excellent optical and electrical properties. In this work, aluminum doped zinc oxide thin films were prepared using RF magnetron sputtering of a 4 at% ceramic target. The thermal stability of aluminum doped zinc oxide thin films was studied using various physical and structural characterization methods. It was observed that the electrical conductivity of aluminum doped zinc oxide thin films deteriorated rapidly and unevenly when it was heated up to 350 °C. When the aluminum doped zinc oxide thin films were exposed to UV ozone for a short time before heating up, its thermal stability and large area homogeneity were significantly improved. The present work provided a novel method for improving the durability of aluminum doped zinc oxides as transparent conductive electrodes in thin film solar cells.
CO2 Emissions due to Cement Manufacture
Authors: Li Chen , Gong Xian Zheng , Cui Su Ping , Wang Zhi Hong , Zheng Yan , Chi Bi Chuan
Published: June 2011

With increasing concerns about global warming, and the cement plants emitting huge CO2, it is necessary to know how the CO2 emits and how much the CO2 emits due to cement manufacture in both direct and indirect ways. A precise method to calculate CO2 emissions including three processes was established in this paper and a case study was provided. From the case of LQDX plant, we can see the amount of CO2 emissions at the right level. The summary of CO2 emissions is consisted by emissions from raw materials, fuels and electricity. The direct CO2 emissions are 0.822 ton CO2 per ton clinker, and the total CO2 emissions are 0.657 ton CO2 per ton cement in this study. Therefore, the way that CO2 emissions due to cement manufacture was pictured and then measured. An approach provides a basic framework to identify various situations in different cement plants in China and other in the rest of the world. The framework would be useful in quantitatively evaluating CO2 emissions for government to know precisely CO2 emissions in cement plants.
Influence of Particle Size Distribution of Fly Ash on Compressive Strength and Durability of Portland Cement Concrete
Authors: Zhu Jian Ping , Guo Qi Lei , Li Dong Xu , Li Cun Jun
Published: June 2011

The Present Research Investigates the Compressive and Durable Properties of Concretes with Fly Ash (FA), a by-Product of Coal-Fired Power Plants. for this Purpose, a Reference Sample and Twenty-one Concretes Containing FA Were Tested. the FA Was Sieved to 200, 300, and 400 Mesh. then FA Was Mixed into Concrete with Different Content. Compressive Strength at 7 and 28 Days, and Chloride Penetration Properties Were Measured. it Is Concluded that FA Can Be Used in the Production of Concrete. in Addition, the FA Concretes Present Satisfactory Physical Properties. when Proper Amount of FA Were Added the Concrete Properties Can Be Better than the Blank one.
Matrix-Based Model of the Carbon Footprint Analysis for Thermal Power Generation in China
Authors: Sun Bo Xue , Gong Xian Zheng , Liu Yu , Chen Wen Juan , Wang Zhi Hong
Published: June 2011

With the increasing seriousness of climate change problem, carbon footprint has become a very useful method to measure carbon emissions and has been widely accepted. In modern industry, electricity is almost consumed in all industry processes, and electricity is the first "footprint" of most products. As carbon emissions is always measured by theoretical estimation from input inventory but not experimental data, the input inventory of electricity generation becomes very important in carbon footprint analysis. Electricity generation is a very complex process, where all input items inter-dependant on each other and the whole system is an infinite cycle net. But in the traditional calculation model of input inventory, the interaction effect of production system is usually neglected. The major work of this study is to make clear the carbon emissions of provision 1kWh thermal power generation to consumers in China in 2006, since thermal power generation takes the most proportion of Chinese electricity. This study used a matrix-based model which includes interaction effect of the system to calculate the input inventory of electricity generation, and then the carbon emissions of thermal electricity generation in China in 2006 can be calculated. The final result of this paper can be used in carbon footprint, Life Cycle Assessment or some other related fields.
Synthesis of Quaternary Ammonium Salt from Rosin and its Inhibition to some Wood Decay Fungi
Authors: Jin Yan , Li Shu Jun , Liang Tao , Chen Zhi Jun
Published: June 2011

Many pine trees could secrete oleo-resin when they were wounded. The oleo-resin was a mixture of turpentine and rosin. After evaporation of volatile turpentine, rosin remained and covered the wound to protect wood from fungi and insects. From this point, rosin protects wood naturally. However, rosin is not bioactive against most wood decay fungi. In this report, a bioactive rosin derivated, quaternary ammonium salt (QAS), was synthesized and its bioactivity against some wood decay fungi was tested. Firstly, the rosin was esterified by epoxy chloropropane with the mole ratio of 1:2, the reaction time of 3.5h at 90°C. The intermediate was 3-rosin acyloxy-2- hydroxypropyl chlorine. Then, the intermediate reacted with demethylamine to produce N-(3-rosin acyloxy- 2-hydroxyl) propyl-N, N dimethylamine at the following conditions: their mole ratio of 1:2, reaction temperature of 80°C and reaction time of 2.5h. Finally, the N-(3-rosin acyloxy-2-hydroxyl) propyl-N, N dimethylamine was quaternized by epoxy chloropropane with the mole ratio of 1:1, the reaction time of 3h at 90°C, and the yield was 72.8%. The chemical structure of the product was identified by FTIR and 1H NMR. The QAS content of the product was characterized by gravimetric analysis with sodium tetraphenylborate as its precipitation reagent, and liquid chromatography analysis (LC) analysis. The antifungal activity of the product was determined by paper-disc method with wood decay fungi such as Trametes versicolor, Gloeophyllum trabeum and wood stain fungi such as Aspergillus niger and Paecilomyces variot Bainier. The anti-fungal experiment results signified that the QAS of rosin is active to these fungi, especially Gloeophyllum trabeum. Since it is produced easily from rosin, which is renewable and not expensive, QAS of rosin could be a potential wood preservative. Further study is planning.
Mechanical Properties and Microstructure of Short Carbon Fiber Reinforced Hydroxyapatite Bio-Composite
Authors: Wang Xin Guang , Gu Wan Li , Niu Zong Wei
Published: June 2011

The short carbon fiber (Cf) reinforced hydroxyapatite (HA) bio-composite was prepared by an in-situ processing. Mechanical properties and microstructure of Cf/HA were investigated. Structures of HA was analyzed using XRD and fracture surface morphologies of bio-composite were analyzed using SEM. Result shows that grain size of HA under hot pressing sintering (1423K, 35MPa) grow up to approximately 50nm. Bio-composite exhibits excellent mechanical properties when Cfmass fraction is 3%, whose flexural strength and flexural modulus reach the maximum values of 130MPa and 36GPa which surpass common level of nature bone. SEM fracture surface morphologies of Cf/HA shows Cfcan be uniformly dispersed in the HA matrix when the mass fraction less than 6%, while when the mass fraction is11%, partial aggregation appears.
Preparation and Characterization of Zn-Containing Hydroxyapatite/TiO2 Composite Coatings on Ti Alloys
Authors: Qi Min , Yang Da Yi , Zhang Jing Ying , Ai Hong Jun
Published: June 2011

In order to improve the osteoblast growth and bacteria resistance, Zn-containing hydroxyapatite (Zn-HA) and titanium oxide (TiO2) composite coatings were prepared to improve binding between coating and Ti substrate. TiO2 film was prepared on the surface of Ti by micro-arc oxidation (MAO) and Zn-HA coating was deposited on TiO2 using sol–gel technique. Phase structure, composition and microstructure of the surface coatings were analyzed by X-ray diffraction (XRD) and Energy Dispersive Spectrometer (EDS), respectively. The adhesion strength between the coatings with different Zn content was measured by tensile testing. The results showed that there was no significant influence of Zn content on adhesion strength between coating and Ti substrate.
Excellent Surface Passivation by Silicon Dioxide Grown with a Electrochemical Method
Authors: Zhang Jun , Lu Wei Ming , Zhou Chun Lan , Wen Zhen Li , Zhao Lei , Li Hai Ling , Diao Hong Wei , Zhang Yao , Wang Wen Jing
Published: June 2011

A novel method to grow silicon dioxide layers for passivating the silicon surface is given more attention. SiO2was grown by applying a positive voltage across silicon wafers in a nitric acid solution at low temperature. After annealing in N2media at 900°C for 20min, excellent surface passivation was achieved. The maximum effective lifetime of the silicon arrived at 29.8μs and 29.75μs, which was three times the value of silicon without passivation. The effective lifetime of other types of silicon could be ten times the initial value without the silicon dioxide. A comparison study of the effect of the FGA, annealing at low temperature and annealing in N2or O2containing medium at high temperature were investigated.
Lower-Temperature Preparation and Photoelectrochemical Properties of Anatase TiO2 Sol
Authors: Deng Jie , Tao Jie , Liu Xiao Li , Wu Tao
Published: June 2011

Considering the deposition of TiO2 films on the substrates with lower melting points, anatase TiO2 sol was directly prepared under lower temperature by an improved sol - gel processing and was characterized by XRD, TEM and FT-IR. The effects of process conditions on the crystallinity, crystalline phase and grain size of TiO2 sol, namely, the mol ratio R of n-butyl titanate and water, pH value, aging time and the preparation temperature，were systematically discussed. The results showed that the mol ratio R and aging time had great influence on the crystallinity of TiO2 sol, whereas pH value and the preparation temperature mainly affected its crystalline phases. Besides, more water and lower pH value led to larger grain of TiO2 sol. The flexible TiO2 film electrodes were fabricated on a transparent indium-doped tin oxide coated PET substrate by means of a doctor-blading method using the mixture of the as-prepared TiO2 sol and P25 TiO2 particles. The photoelectrochemical performance of the TiO2 film electrode in Na2SO4 solution was better than that of the commercial TiO2 sol film, whereas its dye adsorbance was slightly smaller than that of the commercial TiO2 sol film because of its somewhat denser structure which could be improved by optimizing the fabrication process.
Effects of Annealing Treatment on Texture and Stamping Properties of AZ31 Magnesium Alloy
Authors: Li Jing Yuan , Wang Jia Fei , Zhang Dong Liang , Wang Xin Kui
Published: June 2011

The microstructure, texture and basic stamping properties of AZ31 magnesium sheet are studied in this paper with optical microscopy (OM), scan electron microscopy (SEM), X-ray diffraction (XRD) and MTS universal tester. The results show that the basal texture (0002) is enhanced and the grain size decreases as the thickness of sheet decreases. However the texture depresses in the 0.52mm sheet due to the complete recrystallization under deep rolling reduction. The strength and elongation decreases and the strain hardening index (n value) increases as the thickness increases. The precipitation decreases and the basal texture depresses after annealing treatment. The peak value ratio of crystal plane (0002) of 1.3mm sheet reduces from 67% to 53% when annealing treated at 300°C for 2h. In addition, the strain hardening index (n) value reduces from 0.2535 to 0.2053 and the anisotropic index (r) value increases from 1.966 to 2.108 when the sheet is treated at the same condition.
Corrosion Behaviour of Mg-7.3Al Alloy in Buffered Chloride Solutions
Authors: Jia Su Qiu , Gao Wen Ke , Zhao Zhan Kui
Published: June 2011

The Corrosion behaviour of Mg-7.3Al alloy in buffered chloride solutions was investigated in the paper. The corrosion resistances of Mg-7.3Al alloy were evaluated in different borate capacity and pH by immersion test and polarization curves. The influences of immersion time, pH and buffer borate capacity were analyzed. The results revealed that the corrosion rate of Mg-7.3Al alloy depends on the pH of corrosive solution and has no relationship with buffer capacity. In the pH 6.5 and 2g / L buffer solution, the morphologies of Mg-7.3Al alloy consist of porous pits and protuberant second phases. There are seriously corroded area and macro-uncorroded area or protuberant second phases on the sample surface. The corossion potentials of the mg alloy is kept the same value in the pH 9 solution, regardless of borate capacity is 1g/Lor 2g/L, which are higher than that in the neutural chloride solution or acid solution (pH=6.5). Borate may play an inhibition role for mg alloy by the quick corrosion test of polarisation curves.
Effects of Sr Addition on Mechanical Properties and Microstructure of Mg-6Al Magnesium Alloy
Authors: Fan Jin Ping , Wang She Bin , Xu Bing She
Published: June 2011

The effects of Sr addition on the mechanical properties and microstructure of Mg-6Al mag- nesium alloy both at 25 °C and at 175 °C were investigated by means of OM, SEM and EDS and XRD. Upon the Sr addition of 2%, the tensile strength was increased by 7.2% to 184.4MPa at 25 °C, while it was increased by 30% to 155.4MPa at 175 °C. The strengthening mechanism of Mg-6Al-xSr at lower temperature (25 °C) was different from that at higher temperature (175°C). The results show that the addition of strontium effectively improved the microstructure and mechanical properties of magnesium alloy.
Low Cycle Fatigue Behavior of As-Extruded AZ31 Magnesium Alloy
Authors: Mao Ping Li , Liu Zheng , Li Yang , Chen Li Jia
Published: June 2011

The investigation on fatigue behavior and fracture surfaces of fatigued specimens of as-extruded AZ31 magnesium alloy can provide a reliable theoretical foundation for both fatigue resistant design and reasonable application of magnesium alloys. Through total-strain-amplitude controlled fatigue tests and analysis on fracture surfaces of fatigued specimens, the behavior of cyclic stress response and fatigue life as well as fracture mechanism were identified for as-extruded AZ31 magnesium alloy. The experimental results show that the extruded AZ31 alloy exhibits significant cyclic strain hardening, the relation between elastic strain amplitude, plastic strain amplitude and reversals to failure can be described by Basquin and Coffin-Manson equations respectively. In addition, it has been found that fatigue cracks initiate and propagate in a transgranular mode.
Corrosion Resistance of Modified Silane Films Formed on AZ31 Magnesium Alloys
Authors: Cao Xian Long , Pan Fu Sheng , Deng Hong Da , Cai Wei
Published: June 2011

This present work investigated the corrosion behavior of AZ31 magnesium alloy substrates pre-treated with bis-[triethoxysilylpropyl] tetrasulfide silane modified with cerium nitrate. The corrosion behavior of the pre-treated substrates in 0.005M sodium chloride solutions was assessed by potentiodynamic polarization, open circuit potential and electrochemical impedance spectroscopy (EIS). The results showed that the silane pre-treatments improved the corrosion resistance of the AZ31 magnesium alloy substrates in the presence of chloride ions. Especially the addition of cerium nitrate played an important role in reducing the corrosion activity.
Preparation of Mg-Cu-Y and Mg-Ni-Gd Based Amorphous Brazing Material
Authors: Cao Mei Qing , Xie Kun
Published: June 2011

Several Mg-Cu-Y and Mg-Ni-Gd based amorphous brazing materials were prepared by means of rapid solidification. The amorphous structure was examined by XRD and DSC, glass formation ability and melting feature of the amorphous brazing material were also studied. Results show that the alloys prepared are all amorphous and Mg-Ni-Gd alloy has higher glass formation ability and thermal stability.
Effect of Calcium and Strontium on Microstructure of AZ31 Wrought Magnesium Alloys
Authors: Zhu Zhuang Qing , Pan Fu Sheng , Zhao Chong , Hu Yao Bo
Published: June 2011

AZ31 wrought alloys at as-cast state with different microcontent calcium and strontium was studied by optical microscopy, X-ray diffraction, scanning electron microscopy and energy dispersive X-ray analysis. The study shows that the primary dendrite spacing and the secondary dendrite arm spacing can be refined significantly by Ca or Sr element. At 0.5wt.% Sr and 1.8wt.% Ca, the best refinement effect is fulfilled, its primary dendrite spacing and secondary dendrite arm spacing decreased from 292μm to 87μm. The Al4Sr intermetallic compound is observed at grain boundaries When Sr was added. The Al4Sr disappears after Ca added, a new ternary intermetallic compound (Mg, Al)2Ca presents. The addition of Sr and Ca can cause microhardness increasing.
Study to Yield and Uniformity of Mn in High-Mn Contained Mg-Mn Master Alloy Prepared by Stirring Cast
Authors: Li Rui , Gao Jia Cheng , Fan Ke
Published: June 2011

The yields and uniformities of Mn in high Mn-content (Mn≥10wt%) Mg-Mn master alloys have been studied in this paper. Pure Mn powder and Mg ingot were used to be raw materials and put into graphite pot. The master alloys were prepared by stirring cast in an induction furnace with Ar protection atmosphere at the operating power of 10KW. Master alloy melts were cooled in three different conditions, which were cooling in air with graphite pot, cooling in water with graphite pot and cooling in copper mould. The contents and distribution of Mn in master alloys were tested by GB\T 1506-2002. The results shown that the yields of Mn were improved with the increase of Mn particle size and the better uniformity was obtained by faster cooling speed of master alloy melt and smaller particle size of Mn powder, which were agree with the calculated results.
Wear Resistance Property of AM60 Magnesium Alloy Modified by Plasma Surface Treatment
Authors: Sun Jin Quan , Yan Zi Feng , Cui Hongzhi , He Qing Kun , Yang Hong Guang , Xiao Cheng Zhu
Published: June 2011

In this work, an attempt has been made to improve the wear and abrasion properties of AM60 magnesium alloy by surface modification using a self-designed plasma generator as thermal source. The influence of surface modification on the microstructure and wear resistance of melting layer was studied by optical microscope (OP), scanning electron microscopy (SEM), energy disperse spectroscopy (EDS) and friction experiment, respectively. The results show that microhardness of the surface-melted samples is obviously higher than untreatment sample. The wear resistance has been enhanced by solid solution strengthening and grain refining strengthening.
Effect of Hot Pressing Technology on the Microstructure and Mechanical Properties of ZrO2 Nano-Composite Ceramic Tool and Die Material
Authors: Yi Ming Dong , Xu Chong Hai , Zhang Jing Jie , Jiang Zhen Yu
Published: June 2011

A new nano-composite ceramic tool and die material was prepared by vacuum hot pressing technique. The effect of hot pressing technology on the microstructure and mechanical properties of ZrO2 nano-composite ceramic tool and die material was investigated systemically, and the ceramic tool and die material with good mechanical properties was fabricated successfully. Results show that, the highest flexural strength, fracture toughness and hardness of ZrO2 nano-composite ceramic tool and die material reaches 1055 MPa, 10.57 MPa∙m1/2 and 13.59 GPa, respectively by means of the vacuum hot pressing technique at 1430 °C for 60min at 35MPa. The flexural strength and fracture toughness has been improved greatly by the optimization of hot pressing technology. In the materials, the optimum sinter process could ensure the t-ZrO2 stabilized till room temperature that can enhance the toughening effect of ZrO2. The microstructure of ZrO2 nano-composite ceramic tool and die materials were improved by the optimization of hot pressing technology, and the fracture mode is the typical mixed trans/inter-granular fracture mode.
Study of Roughness for Electroplating of Composite Texture on Material Surface
Authors: Tan Yong , Liu Chang Sheng , Sun Jie , Yu Xiao Zhong
Published: June 2011

In this paper, the intermediate layer was prepared by electroplating of nickel and WC particles. The parameters, including current density and temperature, were studied in the experiments. The measured methods, which consisted of surface roughometer and SEM, were used to character the roughness and microstructure. The experimental results showed that the optimizing parameters of the electroplating for composite texture were as follows, temperature was 65°C, current density was 5A/dm2 and the pH value was 6.5. Under the condition of optimizing parameters the values of roughness Ra were in the range from 4.5 to 6.7 μm. From the microstructure observation by SEM revealed that the particles on the surface were well distributed. The difference of the electroplating time induced the different nickel contents which affected the binding force. The roughness of the surface was in the range of 1.35 to 4.47 μm.
Effect of Laser Power on the Microstructure of Ni-P Layer Deposited on Aluminum Substrate
Authors: Yang Yue , Hu Jian Dong
Published: June 2011

Laser processing of Ni-P layer electroless deposited on aluminum substrate was carried out by Nd-YAG pulsed laser. Different laser processing parameters were selected. When lower laser power density was employed, the modified Ni-P layer was obtained, however, when employed laser power density increased, laser alloying of Ni-P layer with aluminum substrate occurred. The characteristic dendritic or lamellar microstructures were observed in the alloyed layer. The phase constituents of the alloyed zones determined by X-ray diffraction are consisted of nickel-aluminum intermetallic compounds NiAl, Al3Ni and Al3Ni2, as well as some non-equilibrium phases, depending on the employed laser power density.
Effect of Processing on Density of Mg-6Zn-0.5Y Alloy
Authors: Jia Zheng , Zhang Zhi Qiang , Le Qi Chi , Cui Jian Zhong
Published: June 2011

Effect of different melt temperatures, holding time, cooling rate and C2Cl6 degasser treatment on the density of Mg-6Zn-0.5Y alloy was studied. The experimental results indicated that the density of RPT samples decreased with increasing of melt temperature, which indicating that the hydrogen content increased with the increment of temperature. And the results also showed that the density of RPT samples rapidly decreased at first and then decreased slowly with increasing of holding time, suggesting that the hydrogen content rapidly increased at first and then reached a saturated state with increasing of holding time. When cooling rate increased, the density of ingots gradually increased at the same melt temperature. When the melt was treated by 1%, 3% and 5% C2Cl6 degasser at 720°C, the density of ingots gradually increased compared with the ingot without treatment by C2Cl6 degasser. The density of ingot reached the maximum value when C2Cl6 degasser content was 3%, i.e, the ingot density value increased from 1.8649g.cm-3 of the untreated sample to 1.8774g.cm-3 of the sample treated by 3% C2Cl6 degasser, indicating that 3% C2Cl6 degasser treatment has an optimum degassing effect.
Microstructure and Properties of TiAlN Compound Films Fabricated on AZ91D Alloy by Magnetron Sputtering
Authors: Lu Sheng , Wu Liang Wen , Chen Jing
Published: June 2011

By means of reaction magnetron sputtering, TiAlN ternary compound films were deposited on AZ91D magnesium alloy substrates. The influence of partial pressure ratio of N2 to Ar (N2/Ar) on the microstructure and properties of TiAlN film was explored with scanning electron microscopy (SEM), X-ray diffraction (XRD), and tests of microhardness, hydrophile and corrosion resistance. The results show that with the increase of N2/Ar partial pressure ratio from 0.5:10 to 1.5:10, Ti2N becomes the main film phase and the size of the crystals cluster decreases. As the N2/Ar ratio is as higher as 2:10, the film crystals change from Ti2N to TiN with coarse clusters. With increase of N2/Ar rate, the hardness, hydrophobic nature and corrosion resistance of the TiAlN film tend to increase.
A Morphology Observation of β-Mg17Al12 Phase in AZ80 Magnesium Alloy Subjected to Hot Compression Deformation under Different Conditions
Authors: Yang Ya Qin , Zhang Zhi Min , Li Bao Cheng
Published: June 2011

The precipitation mechanism of secondary-precipitated phase β in AZ80 magnesium alloy during the hot compression deformation under different temperature was investigated. The results show that there are β-Mg17Al12 phases with different morphology and precipitation mechanism in the microstructure of AZ80 alloy deformed both in two-phase region、critical region and single-phase region. β-Mg17Al12 phases were directly deformed and broken to be strip form during the compression under 200、250、300 and 350°C. A lot of fine granular second phase particles precipitated with the grain refinement simultaneously in AZ80 alloy deformed in two-phase region with tremendous deformation. There are also fine granular second phase particles precipitated in the alloy deformed in critical region. There are massive β-Mg17Al12 phases precipitated in the alloy deformed under higher temperature such as 350 and 400°C during the water cooling after the compression, the high power observation of which is fine and tightly lamellar microstructure. Compared with coarse reticular β-Mg17Al12 phases in the as-cast microstructure of AZ80 alloy, the morphology of β-Mg17Al12 phases precipitated during the hot compression has obvious improvement.
Reconditioning of Electroless Nickel Plating Bath on Magnesium Alloys
Authors: Liu Xin Kuan , Liu Ping , Xiang Yang Hui , Hu Wen Bin , Ding Wen Jiang
Published: June 2011

The reconditioning operation of electroless nickel (EN) plating was studied and the influence of aging on the deposition speed, phosphorous content and stability of the operating solution was analyzed. The results showed that aging of the EN bath caused a dramatic declining of the deposition speed and the bath stability, while a slow increasing in phosphorous content of the deposit. Fluoride of NaF and NiF2 would precipitate from the bath due to the accumulation of sodium and fluorine ions during the replenishment. The sediment of NaF and NiF2 had a detrimental effect on the EN process and would deteriorate the protection of EN plating.
Absorption Peaks Study of β-Zn3BPO7 Crystal in THz Band
Authors: Ju Hai Lang , Li Xiong , Li Bao He , Hou Bi Hun
Published: June 2011

Using electro-optic sampling technique and THz time-domain spectroscopy-transmission equipment, the reference THz wave and the sample THz wave has been measured from 0.3 THz to 3.0 THz and the absorption index has been obtained. Absorption peaks of β-Zn3BPO7crystal sample were found in four points. The important condition of direct interaction between lattice and light is that they must have the same frequency and wave vector, also lattice vibration mode should be transverse because the light is electromagnetic wave. The absorption peaks are found multiple of the optical phonon basically after calculation. The sample shows great resonance absorption.
Magnetic and Mechanical Properties of Directionally Solidified Fe-6.5wt.%Si Alloy
Authors: Deng Y. S. , Fang Xian Shi , Ye Feng , Qiao Y. , Lin Jun Pin , Chen G.L.
Published: June 2011

Directional solidification technique was employed to produce Fe-6.5wt.%Si alloy with coarse columnar-grain structure, which was almost single crystal. The sectional diameters of columnar grains range from 2.2 to 6.8 mm. The saturation magnetic induction was 2.39 T. In this work, grain growth started from either a Fe-6.5wt.%Si crystal which was not melted at bottom of the specimen or a freely nucleated Fe-6.5wt.%Si crystal as the specimen was completely melted. It was found that the starting situation of the directional solidification plays an important role in the crystal orientation, and hence in properties.
Microstructure and Thermo-Physical Properties of TiB2/Si-30Al Composite for Electronic Packaging Applications
Authors: Gan Gui Sheng , Zhang Lei , Lu Yi , Yang Bin
Published: June 2011

2wt.%TiB2/Si-30Al composite was prepared by in-situ reaction and spray forming first and then by hot isostatic pressing (HIP). The microstructure and thermo-physical properties of the composite were investigated by means of scanning electron microscopy, and thermal expansion analyzer respectively. The results show that the microstructure of the TiB2/Si-30Al composite consists of a continuous network of primary Si (~35μm), interpenetrating secondary Al phase, and fine TiB2particles (1~2μm). The TiB2particles were uniformly distributed in the Si-30Al alloy matrix. After HIP, the pores in the TiB2/Si-30Al composite were almost eliminated, and the relative density of the composite was up to 98.9%. The 2wt.%TiB2/Si-30Al composite after the HIP exhibits good thermo-physical properties, including lower coefficient of thermal expansion (CTE) (6.6´10-6×K-1) and higher thermal conductivity (84 W×m-1×K-1).
Microwave Dielectric Properties of Ca(Li1/3Nb2/3)O3-δ Ceramics with ZnO Additive
Authors: Liao Ji Hong , Dai Ying , Chen Wen , Tan Lian Xiang , Qu Shao Hua
Published: June 2011

The complex perovskite compound Ca(Li1/3Nb2/3)O3-δ(CLN) ceramics have received much attention due to the superior properties and relatively low sintering temperature 1150°C. In order to further low the sintering temperature of the CLN ceramics, enhance the Q · f values and other dielectric properties, the effects of the additive ZnO on the sinterability and dielectric properties of the CLN have been investigated. The CLN ceramics were prepared by conventional solid state ceramic route. With the addition of 1.0 wt% ZnO, the sintering temperature of Ca(Li1/3Nb2/3)O3-δ(CLN) ceramics was effectively reduced from 1150◦C to 1090◦C，and the Q · f value was increased from 18920 to 20950 GHz (at 7.09 GHz). It also possesses compatible dielectric constant εrof 27.8 and τfvalue of -23.57 ppm/◦C. While with the addition of 1.25 wt% ZnO, the Q · f value of Ca(Li1/3Nb2/3)O3-δ(CLN) ceramics sintered at 1150◦C for 3 hours was increased significantly to 32150 GHz (at 7.09 GHz), εrof 28.3 and τfvalue of -18.55 ppm/◦C. The relationship between microstructure and microwave dielectric characteristics was studied using X-ray diffractometer and Scanning electron microscope.