bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of Chemical Solution Deposition‐Derived Lead Hafnate Titanate Thin Films
Authors: Schorn Peter Jörg , Schneller Theodor , Böttger Ulrich , Waser Rainer
Published: April 2005

In this paper, lead hafnate titanate (PHT) was derived by chemical solution deposition (CSD) and characterized as a thin film material. The thin films were tested for the usage as a ferroelectric thin film in view of Ferroelectric Random Access Memory (FRAM) devices and compared with an equivalent lead zirconate titanate (PZT) thin film, which was prepared under the same conditions. After determining the thickness and the morphology of the PHT films, electronic measurements were performed to investigate this material as a promising candidate in view of FRAM applications due to failure mechanisms like fatigue and imprint.
Model Apatite Systems for the Stabilization of Toxic Metals: II, Cation and Metalloid Substitutions in Chlorapatites
Authors: Kim Jean Y. , Dong Zhili , White Timothy J.
Published: April 2005

Environmental chlorapatites, of the form A10(BxC1−xO4)6Cl2, where A=Ca, Cd, or Pb; B/C=P, V, or Cr and 0≤x≤1, were synthesized by solid‐state reactions. Crystal structure variations, primarily lattice parameters, were examined through powder X‐ray diffraction methods, while performance and long‐term durability of these waste form apatites were assessed by a combination of the toxicity characteristic leaching procedure (TCLP) and the American Nuclear Society (ANS) method. As expected, an overall dilation of unit cell edges was observed with increasing ionic substitutions. However, a discontinuity in linearity was often observed, generally forx≥0.5. The correlation of microstructural changes and leach testing shows that lead chlorapatite is found to be more suitable for waste stabilization than calcium and cadmium analogues.
Structure Evolution of an NiO–YSZ Electrocatalytic Electrode
Authors: Aronin Alexander , Abrosimova Galina , Bredikhin Sergei , Matsuda Kazuyuki , Maeda Kunihiro , Awano Masanobu
Published: April 2005

The microstructure and structural evolution in the composite NiO–YSZ electrocatalytic electrode during operation of electrochemical cells for NO decomposition has been observed and investigated. The structure of the electrocatalytic electrode was found to contain two types of pores. The first group includes pores with a size range of 10–100 nm forming chains or bands. They may form channels by overlapping. These pores are located in YSZ grains and they remain unchanged during cell operation. The second group includes smaller pores located in NiO grains at near‐boundary regions with YSZ grains or directly in the NiO–YSZ interface. These regions are unstable during the cell operation and new Ni and NiO grains nucleate and grow in the interfacial areas. The formation of such new grains as a result of the electrochemical processes in the cell has been discussed. The correlation between structure and properties has been studied.
Structural Behavior of Oxygen Permeable SrFe0.2Co0.8Ox Ceramic Membranes with and Without pO2 Gradients
Authors: Li Yaping , Maxey Evan R. , Richardson James W.
Published: April 2005

The oxygen partial pressure (pO2)‐dependent structural behaviors of two dense tubular ceramic membranes in composition SrFe0.2Co0.8Ox with cubic perovskite structure have been investigated by high‐temperature neutron powder diffraction: one in “static” mode and one in simulated‐operation mode in which one side of the membrane was exposed to air and the other side to reducing gases with variable pO2 levels. Rietveld analysis on data collected for the membrane without pO2 gradients showed that the perovskite is stable in pO2 down to ∼10−12 atm, and at ∼10−14 atm it starts to decompose into a three‐phase mixture containing layered intergrowth Ruddlesden–Popper phases Srn+1(Fe,Co)nOx with n=2 and 3, along with CoO with rocksalt structure. Similar phase evolution was observed when insufficient air flowed on the air side of the membrane exposed to a pO2 gradient. The data support a nonlinear model of oxygen content in perovskite across the membrane thickness, corresponding to a pO2 profile that is shallow inside and steep near the reducing side surface. Gas compositions measured with mass spectrometry indicated that oxygen is permeated from the air side to the reducing side of the membrane. The oxygen permeation fluxes at 900°C were estimated to be 0.4–0.9 sccm/cm2 for the ∼1 mm thick membrane containing perovskite, depending upon pO2 gradient.
Atomic Force Microscopy Study and Qualitative Analysis of Martensite Relief in Zirconia
Authors: Deville Sylvain , Chevalier Jérôme , El Attaoui Hassan
Published: April 2005

A recent report [S. Deville and J. Chevalier, J. Am. Ceram. Soc., 86[12], 2225 (2003)] has shown the new possibilities offered by atomic force microscopy (AFM) to investigate martensitic transformation‐induced relief in zirconia. In this paper, we studied qualitatively the surface relief resulting from martensitic tetragonal to monoclinic phase transformation in yttria and ceria‐doped zirconia by AFM. AFM appears as a very powerful tool to investigate martensite relief with great precision. The phenomenological theory of martensitic crystallography could be successfully applied to explain all the observed features. The formation conditions of martensite are discussed, as well as ways of accommodating locally the transformation strain, i.e., self‐accommodating variant pairs and microcracking. Variant growth sequences are observed. These observations bring new insights and explanations on the transformation initiation and propagation sequences.
Combustion Reaction During Mechanical Alloying Synthesis of Ti3SiC2Ceramics from 3Ti/Si/2C Powder Mixture
Authors: Li Jing‐Feng , Matsuki Toshiro , Watanabe Ryuzo
Published: April 2005

Mechanical alloying (MA) synthesis of Ti3SiC2from a stoichiometric elemental powder mixture of Ti, Si, and C was conducted by using a planetary mill with a specially designed MA jar, which enables the real‐time measurement of temperature and gas pressure during the MA process. Sudden gas pressure and temperature rises were detected when the mixed powders were mechanically alloyed for a certain period, and consequently a large amount of Ti3SiC2particles was synthesized. Using the Ti–Si–C system as an example, the present study confirmed the combustion reaction triggered by the ball‐milling process for the first time.
Deterministic Microgrinding, Lapping, and Polishing of Glass–Ceramics
Authors: Lambropoulos John C. , Jacobs Stephen D. , Gillman Birgit E. , Stevens Harrie J.
Published: April 2005

We report a series of microgrinding and polishing experiments on glass–ceramics. Microgrinding includes deterministic microgrinding (two‐body abrasion at fixed infeed rate) and loose abrasive lapping (three‐body abrasion at fixed pressure). We correlate material mechanical properties (Young's modulus, hardness, fracture toughness) and chemical properties (chemical susceptibility or mass loss under chemical attack) with the quality of the resulting surface (surface microroughness and surface grinding‐induced residual stresses). We compare deterministic microgrinding (at fixed infeed) and loose abrasive microgrinding (at fixed pressure) in terms of material removal rates and resulting surface quality.
Thermal Performance of Mechanically Activated Tetracalcium Phosphate
Authors: Gbureck U. , Hofmann M. P. , Barralet J. E.
Published: April 2005

Prolonged high‐energy ball milling of tetracalcium phosphate (TTCP) resulted in a mechanical activation with the formation of nanocrystalline or amorphous domains within the compound. This mechanically activated material demonstrated a completely different thermal behavior compared with highly crystalline TTCP. Differential scanning calorimetry (DSC) measurements indicated the presence of exothermic reactions between 370° and 480°C and between 630° and 930°C for 24 h‐milled TTCP, which could be related to conversion to an apatitic phase and calcium oxide (CaO) and crystallization of these products during heating. X‐ray diffraction analyses showed that mechanically activated TTCP began converting to an apatitic phase at ∼200°C and fully converted to an apatitic phase and amorphous CaO at 600°C, and a crystalline phase of CaO subsequently appeared around 800°–1200°C. Reconversion to TTCP was observed between 1200° and 1400°C. In contrast, crystalline TTCP remained stable up to 500°C and decomposed to an apatitic phase and CaO around 600°–1000°C.
Zirconia–Mullite Composites Consolidated by Spark Plasma Reaction Sintering from Zircon and Alumina
Authors: Rocha‐Rangel Enrique , Díaz‐de‐la‐Torre Sebastián , Umemoto Minoru , Miyamoto Hiroki , Balmori‐Ramírez Heberto
Published: April 2005

Mullite–ZrO2 composites have been fabricated by attrition milling a powder mixture of zircon, alumina, and aluminum metal with MgO or TiO2 as sintering additives, heating at 1100°C to oxidize the aluminum metal, and consolidation by spark plasma sintering (SPS). The influence of the SPS temperature on the formation of mullite, and the density and the mechanical properties of the resulting composites have been studied. For the mullite–zirconia composites without sintering additives, the mullite formation was accomplished at 1540°C. In contrast, for the composites having MgO and TiO2, the formation temperature dropped to 1460°C. The composites without sintering additives were almost fully dense (99.9% relative density) and retained a larger amount of tetragonal zirconia. Those materials attained the best mechanical properties (E=214 GPa and KIC=6 MPa·m1/2). To highlight the advantages of using the SPS technique, the obtained results have been compared with the characteristics of a mullite–zirconia composite prepared by the conventional reaction‐sintering process.
Direct Observations of Debonding of Reinforcing Grains in Silicon Nitride Ceramics Sintered with Yttria Plus Alumina Additives
Authors: Becher Paul F. , Painter Gayle S. , Lance Michael J. , Ii Seiichiro , Ikuhara Yuichi
Published: April 2005

As in fiber‐reinforced composites, debonding, which allows the elongated reinforcing grains to at least partially separate from the rest of the matrix, is a critical part of the toughening mechanism in self‐reinforced silicon nitrides. In situ high‐resolution electron microscopy observations reveal that the debonding path can occur at the interface between the grains and continuous nanometer‐thick intergranular film (IGF) or within the IGF depending on the film's composition, which varies with the yttria to alumina ratio in the fixed total amount of sintering additives. Theoretical calculations reveal that the bonding across the interface can be weakened by decreasing the Al and O content (z) of the epitaxial Si6–ZAlZOZN8–Z layer on the grains, which is consistent with the observations of interfacial debonding. However, evidence also indicates that weakening of the amorphous network of the IGF occurs with increase in yttrium levels that can be responsible for the observed mixture of debonding by crack propagation along the interface and within the IGF when the sintering additive contains the highest yttria:alumina ratio.
Fabrication of Porous Hydroxyapatite Using Hydrothermal Hot Pressing and Post‐Sintering
Authors: Nakahira A. , Murakami T. , Onoki T. , Hashida T. , Hosoi K.
Published: April 2005

In the present study, a hydrothermal hot pressing (HHP) method was used to fabricate porous hydroxyapatites with high strength. In particular, an interconnected matrix of hydroxyapatite was achieved by solution precipitation and the application of compressive stress during HHP. Hydroxyapatite samples post‐sintered after this HHP treatment had a lower relative density and higher open porosity than those prepared by normal sintering. An examination of the pore characteristics suggested that the samples after HHP treatment and post‐sintering had a high amount of open pores with a large and round morphology, whereas the samples prepared by normal sintering showed a denser microstructure, with a sharp‐edged‐pore morphology.
Ceramic Composites with Three‐Dimensional Architectures Designed to Produce a Threshold Strength—I. Processing
Authors: Fair Geoff E. , Lange F. F.
Published: April 2005

A processing method was developed to produce a composite architecture that consisted of polyhedra of one material separated from one another by thin layers of a second material. The materials used for this study were selected so that the material separating the polyhedra would develop large compressive stresses during cooling because of differential thermal contraction. This architecture was developed to determine if it could be used to produce a ceramic composite that exhibited an isotropic threshold strength; a threshold strength has been previously demonstrated for periodic laminates containing thin layers in residual compression. To produce the current architecture, spherical alumina agglomerates were produced by suspending aqueous slurry droplets in an upward flow of a hygroscopic liquid; during the suspension period, the water was absorbed from the droplets, thereby consolidating the particles within an agglomerate. The agglomerates were then coated with thin layers of mullite–alumina using methods commonly employed in the pharmaceutical processing industry. The coated agglomerates were then consolidated into compacts by a two‐step process in which the agglomerates were first uniaxially pressed at low pressure and then isopressed at high pressure. The uniaxial consolidation introduced a small degree of anisotropy into the composite architecture. Edge‐cracking was observed for compressive layers containing 55 vol% mullite, thereby confirming that the appropriate compressive stresses were developed within the architecture.
Effect of Stacking Layers on the Microwave Dielectric Properties of MgTiO3/CaTiO3 Multilayered Thin Films
Authors: Lee Byoung Duk , Lee Hong Ryul , Yoon Ki Hyun , Kang Dong Heon
Published: April 2005

Effect of stacking layers on the microwave dielectric properties of the MgTiO3/CaTiO3 (MTO/CTO) multilayered thin films prepared by the metalorganic solution deposition technique (MOSD) was investigated. As the thickness of CTO film in the MTO/CTO multilayered films increased, the dielectric constant (K) increased and temperature coefficient of dielectric constant (TCK) changed from positive to negative values by dielectric series mixing rule. Especially, MTO(100 nm)/CTO(200 nm) multilayered films exhibited a TCK of +10 ppm/°C, indicating temperature stability. The dielectric losses (tan δ) of MTO/CTO multilayered films increased with an increase of CTO layers. This result was attributed to the fact that the stresses induced by the higher thermal‐expansion coefficient of CTO than that of MTO. Also, as compared with MTO(100 nm)/CTO(200 nm) film, the K and TCK of MTO(50 nm)/CTO(200 nm)/MTO(50 nm) film were not changed, but the dielectric losses increased. This result indicated that the dielectric loss was affected by the number of interfaces between CTO and MTO layers.
Preparation of Ca3Co4O9 and Improvement of its Thermoelectric Properties by Spark Plasma Sintering
Authors: Liu Yuheng , Lin Yuanhua , Shi Zhan , Nan Ce‐Wen , Shen Zhijian
Published: April 2005

The precursor powders of Ca3Co4O9 were synthesized by a sol–gel method. The results of X‐ray diffraction and thermogravimetric and differential thermal analyses patterns indicate that pure Ca3Co4O9 powders could be obtained by calcining the precursor at 800°C for 2 h. High dense Ca3Co4O9 ceramic samples (∼99% of theoretical density) were prepared by the spark plasma sintering (SPS) method. Compared with the conventional sintering (CS), the SPS samples exhibit much higher electrical conductivity and power factor which are respectively about 118 S/cm and 3.51 × 10−4 W·(m·K2)−1. The SPS method is greatly effective for improving the thermoelectric properties of Ca3Co4O9 oxide ceramics.
Sintering Additives to Eliminate Interphases in Cordierite Ceramics
Authors: Shi Zhi Ming
Published: April 2005

Effects of the sintering additives CeO2and K2O on eliminating interphases of cristobalite and spinel were studied by means of XRD, SEM/energy‐dispersive spectrometer, and TMA techniques to obtain high cordierite contents. Adding 4 wt% CeO2significantly stimulates the conversion of cristobalite to cordierite, depresses spinel formation and yields less glassy phase. It is helpful to prepare a ceramic with a high content of cordierite and a low thermal expansion coefficient when sintered at 1400°C for 3 h. Addition of 1–2 wt% K2O results in a large amount of glassy phase and is less effective in eliminating the interphases.
Aqueous Synthesis of Y2O2S:Eu/Silica Core‐Shell Particles
Authors: Chung Chau‐Chyun , Jean Jau‐Ho
Published: April 2005

A layer‐by‐layer method is used to coat silica on the red phosphor powders of Y2O2S:Eu in aqueous solutions. A cationic polymer of polyethylenimine (PEI) is used to form the first‐layer coating, and the precipitating sodium silicate solution, to form negatively charged silica film on the PEI‐coated phosphor powder as the second‐layer coating. Repetition of the above coating process in aqueous solutions, a uniform, multiple silica/PEI bilayer coating on phosphor powder is formed.
Effects of the Weak Absorption Tail on the Transmission Loss of Ge–Sb–Se Optical Fibers
Authors: Jin Chung Woon , Je Park Bong , Seok Seo Hong , Tae Ahn Joon , Lee Myung‐Hyun , Choi Yong Gyu
Published: April 2005

Selenide glass optical fibers were fabricated for Ge30Sb10Se58S2 and Ge20Sb10Se70 glasses. Their transmission loss has been measured and compared with the theoretical attenuation loss that was calculated taking into account the electronic transition absorption, Rayleigh scattering, and multiphonon absorption. A low attenuation loss of the Ge20Sb10Se70 glass composition in 1.2–1.7 μm range has been expected due to its high optical band gap energy compared with the Ge30Sb10Se58S2 glass. However, the measured attenuation loss of the Ge30Sb10Se58S2 glass fiber was ∼13 dB/m at 1.5 μm while Ge20Sb10Se70 glass showed ∼82 dB/m. An enhanced weak absorption tail due to the localized states of the Ge20Sb10Se70 glass was responsible for this behavior. Structural defects are related to the localized states and discussed for the present glass compositions.
Low‐Temperature Synthesis of Nanosized Bismuth Ferrite by Soft Chemical Route
Authors: Ghosh Sushmita , Dasgupta Subrata , Sen Amarnath , Sekhar Maiti Himadri
Published: April 2005

The present research describes a simple low‐temperature synthesis route of preparing bismuth ferrite nanopowders through soft chemical route using nitrates of Bismuth and Iron. Tartaric acid is used as a template material and nitric acid as an oxidizing agent. The synthesized powders are characterized by X‐ray diffractometry, thermogravimetry and differential thermal analysis, infrared spectroscopy, and scanning electron microscopy. The particle size of the powder lies between 3 and 16 nm. In the process, phase pure bismuth ferrite can be obtained at a temperature as low as 400°C, in contrast to 550°C for coprecipitation route. On the other hand, we find that, like solid state reaction route, Pechini's autocombustion method of synthesis generates a lot of impurity phases along with bismuth ferrite.
Reaction‐Formed Porous Yb4Si2N2O7 Materials with Uniform Open‐Cell Network Structure
Authors: Zhu Xinwen , Zhou You , Hirao Kiyoshi
Published: April 2005

A novel porous Yb4Si2O7N2 material with uniform open‐cell network structure was fabricated from the reaction between Si3N4, Yb2O3, and SiO2. The formation of Yb4Si2O7N2 during heating was studied using X‐ray diffractometry. The porous structure was characterized using scanning electron microscopy and mercury porosimeter. It is shown that the formation of Yb4Si2O7N2 phase starts at ∼1150°C and completes at 1350°C for 4 h, accompanied by the development of open‐cell network structure. The necks between Yb4Si2O7N2 particles become much thicker with increasing temperature because of the coarsening of Yb4Si2O7N2 particles, thus leading to a uniform three‐dimensional network structure. Furthermore, the pore size can be well controlled by adjusting reacting temperature and altering atmosphere.
Structural Variation of the BaTi4O9 Thin Films Grown by RF Magnetron Sputtering
Authors: Jang Bo‐Yun , Jeong Young‐Hun , Lee Suk‐Jin , Lee Kyong‐Jae , Nahm Sahn , Sun Ho‐Jung , Lee Hwack‐Joo
Published: April 2005

BaTi4O9 thin films were grown on a Pt/Ti/SiO2/Si substrate using rf magnetron sputtering and the structure of the thin films were then investigated. For the films grown at low temperature (≤350°C), an amorphous phase was formed during the deposition, which then changed to the BaTi5O11 phase when the annealing was conducted below 950°C. However, when the annealing temperature was higher than 950°C, a BaTi4O9 phase was formed. On the contrary, for the films grown at high temperature (>450°C), small BaTi4O9 grains were formed during the deposition, which grew during the annealing. The homogeneous BaTi4O9 thin films were successfully grown on Pt/Ti/SiO2/Si substrate when they were deposited at 550°C and subsequently rapid thermal annealed at 900°C for 3 min.
Camber Development During the Cofiring of Bi‐Layer Glass‐Based Dielectric Laminate
Authors: Chang Jui‐Chuan , Jean Jau‐Ho
Published: April 2005

Camber and stress development during the cofiring of a bilayer low‐temperature‐cofired glass dielectric laminate, composed of a crystallizable glass (CG) and ceramic‐filled glass (CFG), have been investigated. The sintering mismatch stress is calculated from the camber development during cofiring and found to be less than those of sintering potentials. This explains the absence of defects, such as de‐densification, de‐bonding, and channel cracks in the coifed multilayer CG/CFG laminates. Reasonably good agreement is found between the sintering mismatch stress obtained from the camber rate data and that calculated using the linear strain rate difference from the dilatometric data.
Sol–Gel Synthesis and Characterization of Alumina–Calcium Hexaaluminate Composites
Authors: Vishista K. , Gnanam F. D. , Awaji H.
Published: April 2005

Boehmite sol was prepared by hot water hydrolysis of aluminum iso‐propoxide using nitric acid as the catalyst. Calcium nitrate to yield 0–20 vol% calcia was added to the boehmite sol. The boehmite with additives was calcined at 600°C for 3 h. The calcined powder was milled at 230 rpm for 6 h and particle size was measured using Laser particle size analyzer. The powder samples were calcined at 1600°C for 3 h and the formation of calcium hexaaluminate was discussed using phase diagram, transmission electron microscope, energy dispersive spectra, and X‐ray diffraction spectra. The powder samples calcined at 600°C for 3 h were compacted into cylindrical pellets and sintered at temperatures ranging from 1400° to 1600°C for 6 h and the formation of hexaaluminate (platelike) grains were confirmed using Scanning electron microscope and optical microscopy.
Increased expression of histone deacetylase 2 is found in human gastric cancer
Authors: SONG JAEHWI , NOH JI HEON , LEE JONG HEUN , EUN JUNG WOO , AHN YOUNG MIN , KIM SU YOUNG , LEE SUG HYUNG , PARK WON SANG , YOO NAM JIN , LEE JUNG YOUNG , NAM SUK WOO
Published: April 2005

Accumulated evidence has established that aberrant regulation of histone deacetylases (HDACs) is one of the major causes of the development of human malignancies. Among different iso‐enzymes of HDAC and sirtuins grouped as the HDAC super family, little is known as to how histone deacetylase 2 (HDAC2) causes carcinogenesis in solid tumors. Here, in order to investigate the possible role of HDAC2 in gastric carcinogenesis, we analyzed the expression of HDAC2 in 71 gastric adenocarcinomas by immunohistochemistry. Moderate to strong expression of HDAC2 was found in 44 (62%) out of a total of 71 tumors. The majority of positive tumors, which were detected in the nucleus but not in normal gastric epithelium, did not express HDAC2 or showed only weak positive staining. Interestingly, we also noted that HDAC2 expression appeared to be associated with tumor aggressiveness as HDAC2 expression was observed to be statistically significant in advanced gastric cancer (P=0.0023, Chi‐square test) and in positive lymph node metastasis (P=0.0713, Chi‐square test). Taken together, these results suggest that HDAC2 may play an important role in the aggressiveness of gastric cancer.
Correlation between adjuvanticity and immunogenicity of cholera toxin B subunit in orally immunised young chickens
Authors: MAYO SUSAN , ROYO FELIX , HAU JANN
Published: April 2005

The aim of the present study was to investigate whether the adjuvanticity of the cholera toxin B (CTB) subunit was correlated with its immunogenicity in young orally immunised chickens. Thirteen 15‐day‐old chickens were orally immunised with bovine serum albumin (BSA) glutaraldehyde coupled to CTB. The chicken antibody (IgG) concentrations against BSA and CTB, respectively, were quantified by ELISA. A significant positive correlation (r=0.66, n=39, p<0.001) between the concentrations of immunospecific antibodies with specificities against BSA and CTB, respectively, demonstrated that the adjuvanticity of CTB is correlated with its immunogenicity.
Progressive transformation of germinal center presenting with histological features of hyaline‐vascular type of Castleman's disease
Authors: KOJIMA MASARU , NAKAMURA SHIGEO , MIYAWAKI SHUUICHI , OHNO YOSHIHIRO , SAKATA NORIYUKI , MASAWA NOBUHIDE
Published: April 2005

We report three cases showing progressive transformation of the germinal center (PTGC) with histological features reminiscent of the hyaline‐vascular (HV) variant of Castleman's disease (CD). Each case contained a few small HV germinal centers as well as PTGC and hyperplastic germinal centers with or without follicular lysis. Moreover, some of the PTGC were penetrated by hyalinized small vessels. Our three cases also showed some of the characteristic histological findings of HV type of CD: (i) reactive lymphoid follicles with small hyaline‐vascular germinal centers surrounded by small lymphocytes in a concentrated fashion; (ii) a few small foci of plasmacytoid monocytes; (iii) perivascular fibrosis; (iv) interfollicular vascularity; (v) tight/concentric pattern of the follicular dendritic cell network; and (vi) absence of CD57+ T‐cells in the HV follicles. The PTGC with coexistent HV type of CD may represent a certain form of reactive follicular hyperplasia. The possibility of PTGC should be considered and excluded before diagnosing CD.
Onset exercise hyperaemia in humans: partitioning the contributors
Authors: Wray D. Walter , Donato Anthony J. , Uberoi Abhimanyu , Merlone Joseph P. , Richardson Russell S.
Published: April 2005

Using a step‐wise, reductionist approach we characterized the time course and degree to which mechanical, vasodilatory and cardiac mechanisms contribute to the increase in leg blood flow (LBF) at the onset of dynamic knee‐extensor exercise. Heart rate (HR) and LBF (ultrasound Doppler) were evaluated during (1) voluntary and (2) passive exercise in the seated position, (3) passive exercise in the supine position with the leg above the heart, and (4) passive exercise with measurements made in the non‐moving leg. In trials 2 and 3, the degree of change and time course of peak ΔHR (8.7 ± 2 bpm, seated; 10 ± 1 bpm, supine) and peak ΔLBF (518 ± 135 ml min−1, seated; 448 ± 179 ml min−1, supine) were similar, supporting the concept that the skeletal muscle pump was minimized. Even with the reduction of skeletal muscle pump and metabolic influences (trials 2, 3 and 4) a significant cardio‐acceleration and hyperaemia was seen. In the first 5 s of seated passive exercise, the retrograde component of the blood velocity profile was significantly greater than rest or the 5–20 s interval, which may suggest an arterial inflow that initially exceeded leg vasodilatation. Steady‐state LBF (minutes 2 and 3) remained elevated during voluntary exercise, but returned to near baseline during passive movement. Taken together, these data suggest that cardio‐acceleration (i.e. tachycardia) and mechanical forces other than the skeletal muscle pump play a role in reducing vascular resistance and ultimately increasing LBF at the onset of exercise, followed by steady‐state LBF which matches muscle metabolic demand.
Sex differences in transgenerational alterations of growth and metabolism in progeny (F2) of female offspring (F1) of rats fed a low protein diet during pregnancy and lactation
Authors: Zambrano E. , Martínez‐Samayoa P. M. , Bautista C. J. , Deás M. , Guillén L. , Rodríguez‐González G. L. , Guzmán C. , Larrea F. , Nathanielsz P. W.
Published: April 2005

Compelling epidemiological and experimental evidence indicates that a suboptimal environment during fetal and neonatal development in both humans and animals may programme offspring susceptibility to later development of several chronic diseases including obesity and diabetes in which altered carbohydrate metabolism plays a central role. One of the most interesting and significant features of developmental programming is the evidence from several studies that the adverse consequences of altered intrauterine environments can be passed transgenerationally from mother (F0) to daughter (F1) to second generation offspring (F2). We determined whether when F0 female rats are exposed to protein restriction during pregnancy and/or lactation their F1 female pups deliver F2 offspring with in vivo evidence of altered glucose and insulin metabolism. We fed F0 virgin Wistar rats a normal control 20% casein diet (C) or a protein restricted isocaloric diet (R) containing 10% casein during pregnancy. F1 female R pups weighed less than C at birth. After delivery, mothers received C or R diet during lactation to provide four F1 offspring groups CC (first letter pregnancy diet and second lactation diet), RR, CR and RC. All F1 female offspring were fed ad libitum with C diet after weaning and during their first pregnancy and lactation. As they grew female offspring (F1) of RR and CR mothers exhibited low body weight and food intake with increased sensitivity to insulin during a glucose tolerance test at 110 days of postnatal life. Male F2 CR offspring showed evidence of insulin resistance. In contrast RC F2 females showed evidence of insulin resistance. Sex differences were also observed in F2 offspring in resting glucose and insulin and insulin: glucose ratios. These sex differences also showed differences specific to stage of development time window. We conclude that maternal protein restriction adversely affects glucose and insulin metabolism of male and female F2 offspring in a manner specific to sex and developmental time window during their mother's (the F1) fetal and neonatal development.
Metabolic alkalosis reduces exercise‐induced acidosis and potassium accumulation in human skeletal muscle interstitium
Authors: Street Darrin , Nielsen Jens‐Jung , Bangsbo Jens , Juel Carsten
Published: April 2005

Skeletal muscle releases potassium during activity. Interstitial potassium accumulation is important for muscle function and the development of fatigue resulting from exercise. In the present study we used sodium citrate ingestion as a tool to investigate the relationship between interstitial H+ concentration and K+ accumulation during exercise. Seven healthy subjects performed one‐legged knee‐extensor exercise on two separate days with and without sodium citrate ingestion. Interstitial H+ and K+ concentrations were measured with the microdialysis technique. Citrate ingestion reduced the plasma H+ concentration and increased the plasma HCO3− concentration. Citrate had no effect on interstitial H+ at rest. The increase in interstitial H+ concentration during intense exercise was significantly lower (P < 0.05) with citrate ingestion compared to control (peak interstitial H+ concentration 79 versus 131 nm). After 3 min of exercise interstitial K+ concentration was reduced (P < 0.05) in the citrate (alkalosis) compared to the control experiment (8.0 ± 0.9 versus 11.0 ± 2 mm) and interstitial K+ concentration remained lower during the rest of the exercise period. The present study demonstrated a link between interstitial H+ and K+ accumulation, which may be through the ATP‐sensitive K+ channels (KATP channels), which are sensitive to changes in H+.
Clathrin‐mediated endocytosis in snake motor terminals is directly facilitated by intracellular Ca2+
Authors: Teng Haibing , Wilkinson Robert S.
Published: April 2005

At the snake neuromuscular junction, low temperature (LT, 5–7°C) blocks clathrin‐mediated endocytosis (CME) while exocytosis is largely unaffected. Thus compensatory endocytosis that normally follows transmitter release is inhibited, or ‘delayed’ until the preparation is warmed to room temperature (RT). This delay was exploited to observe how changes in bulk [Ca2+]i directly affect CME. Motor terminals were loaded with fura‐2 to monitor [Ca2+]i. With brief stimulation at LT, [Ca2+]i transiently increased but returned to baseline (∼63 nm) in < 8 min. After 15 min at LT, [Ca2+]i was altered by incubating preparations in the Ca2+ ionophore ionomyocin. Preparations were then warmed to RT to initiate delayed endocytosis, which was quantified as uptake of the fluorescent optical probe sulforhodamine 101. Endocytosis was more rapid when [Ca2+]i increased; the rate at 300 nm Ca2+ was ∼double that under basal conditions. Thus the rate of CME – isolated from stimulation, transmitter release, and other forms of endocytosis – is directly influenced by intraterminal Ca2+.
Role of chloride channels in bradykinin‐induced guinea pig airway vagal C‐fibre activation
Authors: Lee Min‐Goo , MacGlashan Donald W. , Undem Bradley J.
Published: April 2005

We tested the hypothesis that an ionic current carried by chloride ions contributes to bradykinin (BK)‐induced membrane depolarization and activation of vagal afferent C‐fibres. In an ex vivo innervated trachea/bronchus preparation, BK (1 μm) consistently produced action potential discharge in vagal afferent C‐fibres with receptive fields in the trachea or main stem bronchus. The Ca2+‐activated Cl− channel (CLCA) inhibitor, niflumic acid (NFA, 100 μm), significantly reduced BK‐induced action potential discharge to 21 ± 7% of the control BK response. NFA did not inhibit capsaicin‐induced or citric‐acid‐induced action potential discharge in tracheal C‐fibres. The inhibitory effect of NFA was mimicked by another CLCA inhibitor, 5‐nitro‐2‐(3‐phenylpropylamino)‐benzoic acid (NPPB, 100 μm). NFA also inhibited the BK‐induced inward current in gramicidin‐perforated whole‐cell patch‐clamp recordings of capsaicin‐sensitive jugular ganglion neurones retrogradely labelled from the airways. NFA did not inhibit the BK‐induced increase in intracellular free Ca2+. The TRPV1 inhibitor, iodo‐resiniferatoxin (1 μm), also partially inhibited BK‐induced action potential discharge, and the combination of iodo‐resiniferatoxin and NFA virtually abolished the BK‐induced action potential discharge. We concluded that in vagal afferent C‐fibres, BK evokes membrane depolarization and action potential discharge through the additive effects of TRPV1 and Cl− channel activation.
Increase in group II excitation from ankle muscles to thigh motoneurones during human standing
Authors: Marchand‐Pauvert Véronique , Nicolas Guillaume , Marque Philippe , Iglesias Caroline , Pierrot‐Deseilligny Emmanuel
Published: April 2005

In standing subjects, we investigated the excitation of quadriceps (Q) motoneurones by muscle afferents from tibialis anterior (TA) and the excitation of semitendinosus (ST) motoneurones by muscle afferents from gastrocnemius medialis (GM). Standing with a backward lean stretches the anterior muscle pair (TA and Q) and they must be cocontracted to maintain balance. Equally, forward lean stretches the posterior muscle pair (GM and ST) and they must be cocontracted. We used these conditions of enhanced lean to increase the influence of γ static motoneurones on muscle spindle afferents, which enhances the background input from these afferents to extrafusal motoneurones. The effects of the conditioning volleys on motoneurone excitability was estimated using the modulation of the on‐going rectified EMG and of the H reflex. Stimulation of afferents from TA in the deep peroneal nerve at 1.5–2 × MT (motor threshold) evoked early group I and late group II excitation of Q motoneurones. Stimulation of afferents in the GM nerve at 1.3–1.8 MT evoked only late group II excitation of ST motoneurones. The late excitation produced by the group II afferents was significantly greater when subjects were standing and leaning than when they voluntarily cocontracted the same muscle pairs at the same levels of activation. The early effect produced by the group I afferents was unchanged. We propose that this increase in excitation by group II afferents reflects a posture‐related withdrawal of a tonic inhibition that is exerted by descending noradrenergic control and is specific to the synaptic actions of group II afferents.
Electron Beam Damage in Poly(vinyl chloride) and Poly(acrylonitrile) as Observed by Auger Electron Spectroscopy
Authors: Lea Scott , Engelhard Mark , Baer Don
Published: April 2005

AES spectra of spun-cast films of poly(vinyl chloride) (PVC) and poly(acrylonitrile) (PAN) were collected over a period of time to determine specimen damage during exposure to a 10 kV electron beam. For the PVC, loss of chlorine was observed over a period of 203 min to the extent that the final chlorine content was only 20% of its original value. PAN exhibited a loss in nitrogen content over a period of 120 min, but the rate of damage to the polymer was significantly less than PVC. A dose of approximately 7.0 × 10−5 C/cm2 is needed for the chlorine concentration to fall from its original value by 10% (one definition of critical dose). For the PAN film, the critical dose is 1.3 × 10−3 C/cm2, approximately 20 times greater than for PVC, demonstrating a greater resistance to damage from a 10 keV electron beam.
Epitaxial α-Be3N3 Films Analyzed In Situ by AES, XPS, and EELS
Authors: Hernández Wencel De La Cruz , Hernández Jesus Díaz , Soto Gerardo
Published: April 2005

In situ Auger electron, x-ray photoelectron, and electron energy loss spectroscopic data were obtained on epitaxial α-Be3N2 layers grown on (111) and (100) silicon substrates. Films were grown by laser ablating a beryllium foil in molecular nitrogen ambient at 750 °C. The ultrahigh vacuum laser ablation growth system is attached to an analysis chamber equipped with an e-gun, an x-ray source (dual anode Mn/Al), and an electron analyzer MAC-3, all from CAMECA. The spectra show that the film surface is free of impurities, except for traces, of oxygen. Quantitative XPS analysis for the film yields 61, 35, and 4 at % for beryllium, nitrogen, and oxygen concentrations, respectively.
HfO2–ZrO2 Doped Silica Thin Films by XPS
Authors: Armelao Lidia , Gross Silvia , Tondello Eugenio , Zattin Andrea
Published: April 2005

Silica thin films embedding ZrO2 and HfO2 were prepared by spin-coating on silica glass via a modified sol-gel processing. The novel synthetic route is based on the co-polymerization of two organically modified oxozirconium and oxohafnium clusters (M4O2(OMc)12 with M = Zr, Hf and OMc = OC(O)–C(CH3)=CH2)) with (methacryloxypropyl)trimethoxysilane (MAPTMS). The crystalline clusters, which are the precursors for the corresponding metal oxides (MO2) were prepared via the sol-gel route by reacting zirconium or hafnium butoxide with methacrylic acid. The copolymerization of the cluster with previously prehydrolyzed methacrylate-functionalized siloxane, allows the anchoring of the oxoclusters to the forming silica network. Thin films were prepared starting from a THF (tetrahydrofurane) solution with molar ratios Hf4O2(OMc)12: Zr4O2(OMc)12:MAPTMS of 1:1:88. After deposition, the films were annealed 3 h at 800 °C in air to promote the decomposition of the hafnium and zirconium oxoclusters to give the corresponding HfO2 and ZrO2 oxides. The obtained HfO2–ZrO2–SiO2 films resulted transparent, homogeneous and displayed a very good adhesion to the substrate. The composition of the films was investigated by secondary ionization mass spectrometry (SIMS) and x-ray photoelectron spectroscopy (XPS). The depth profiles evidenced a very homogenous distribution of both zirconium or hafnium species within the whole silica films and sharp film-substrate interfaces. As far as XPS analyses are concerned, the main XPS core-levels were analyzed for the annealed sample and the formation of hafnium and zirconium oxides was evidenced.
Beam Damage of Poly(vinyl chloride) [PVC] Film as Observed by X-ray Photoelectron Spectroscopy
Authors: Engelhard Mark , Krishna Abhilash , Kulkarni Pranita , Lee Chi-Ying , Baer Don
Published: April 2005

XPS spectra of a spin-coated film poly(vinyl chloride)(PVC) were collected over a period of 243 min at 303 K to determine specimen damage during long exposures to monochromatic Al Kα x-rays. For this PVC film we measured the loss of chlorine as a function of time by rastering a focused 104.6 W, 100 μm diameter x-ray beam over a 1.4 mm × 0.2 mm area on the sample.
Gender, ageing, and injustice: social and political contexts of bioethics
Authors: Dodds S
Published: April 2005

There has been considerable work in bioethics addressing injustice and gender oppression in the provision of healthcare services, in the interaction between client and healthcare professional, and in allocation of healthcare services within a particular hospital or health service. There remain several sites of continued injustice that can only be addressed adequately from a broader analytical perspective, one that attends to the social and political contexts framing healthcare policy and practice. Feminist bioethicists have a strong track record in providing this kind of analysis. Using current Australian aged care and welfare policy this paper demonstrates some of the ways in which issues of gender, age, and social inequity shape bioethical debate, policy, and practice in the areas of aged care and welfare provision. The author develops an argument that demonstrates the gender injustice underlying health care and welfare policy. This argument recognises the inevitability of human dependency relations, and questions the adequacy of current political theories to address the requirements for full and equal citizenship. The author shows that an adequate analysis of the ethics of aged healthcare depends on sufficient consideration of the social and political context within which healthcare policy is framed and an adequate understanding of human dependency.
“I can put the medicine in his soup, Doctor!”
Authors: Wong J G W S , Poon Y , Hui E C
Published: April 2005

The practice of covertly administering medication is controversial. Although condemned by some as overly paternalistic, others have suggested that it may be acceptable if patients have permanent mental incapacity and refuse needed treatment. Ethical, legal, and clinical considerations become more complex when the mental incapacity is temporary and when the medication actually serves to restore autonomy. We discuss these issues in the context of a young man with schizophrenia. His mother had been giving him antipsychotic medication covertly in his soup. Should the doctor continue to provide a prescription, thus allowing this to continue? We discuss this case based on the “four principles” ethical framework, addressing the conflict between autonomy and beneficence/non-maleficence, the role of antipsychotics as an autonomy restoring agent, truth telling and the balance between individual versus family autonomy.
Clinical bioethics integration, sustainability, and accountability: the Hub and Spokes Strategy: Figure 1
Authors: MacRae S , Chidwick P , Berry S , Secker B , Hébert P , Shaul R Zlotnik , Faith K , Singer P A
Published: April 2005

The “lone” clinical bioethicist working in a large, multisite hospital faces considerable challenges. While attempting to build ethics capacity and sustain a demanding range of responsibilities, he or she must also achieve an acceptable level of integration, sustainability, and accountability within a complex organisational structure. In an effort to address such inherent demands and to create a platform towards better evaluation and effectiveness, the Clinical Ethics Group at the Joint Centre for Bioethics at the University of Toronto is implementing the Hub and Spokes Strategy at seven hospitals. The goal of the Hub and Spokes Strategy is to foster an ethical climate and strengthen ethics capacity broadly throughout healthcare settings as well as create models in clinical bioethics that are excellent and effective.
Should doctors talk to relatives without a competent patient’s consent?
Authors: Mytton O
Published: April 2005

A view from a student: ethical teaching, based on ethical guidelines, is at odds with clinical practice. Is this poor practice, or is the ethical guidance too simple?
High need patients receiving targeted entitlements: what responsibilities do they have in primary health care?
Authors: Buetow S
Published: April 2005

Patient responsibilities in primary health care are controversial and, by comparison, the responsibilities of high need patients are less clear. This paper aims to suggest why high need patients receiving targeted entitlements in primary health care are free to have prima facie special responsibilities; why, given this freedom, these patients morally have special responsibilities; what these responsibilities are, and how publicly funded health systems ought to be able to respond when these remain unmet. It is suggested that the special responsibilities and their place in public policy acquire moral significance as a means to discharge a moral debt, share special knowledge, and produce desirable consequences in regard to personal and collective interests. Special responsibilities magnify ordinary patient responsibilities and require patients not to hesitate regarding attendance for primary health care. Persistent patient disregard of special responsibilities may necessitate limiting the scope of these responsibilities, removing system barriers, or respecifying special rights.
Intermediate studies on refolding of arginine kinase denatured by guanidine hydrochloride
Authors: Tang Hong-Min , Yu Hong
Published: April 2005

The refolding course and intermediate of guanidine hydrochloride (GuHCl)-denatured arginine kinase (AK) were studied in terms of enzymatic activity, intrinsic fluorescence, 1-anilino-8-naphthalenesulfonte (ANS) fluorescence, and far-UV circular dichroism (CD). During AK refolding, the fluorescence intensity increased with a significantly blue shift of the emission maximum. The molar ellipticity of CD increased to close to that of native AK, as compared with the fully unfolded AK. In the AK refolding process, 2 refolding intermediates were observed at the concentration ranges of 0.8–1.0 mol/L and 0.3–0.5 mol GuHCl/L. The peak position of the fluorescence emission and the secondary structure of these conformation states remained roughly unchanged. The tryptophan fluorescence intensity increased a little. However, the ANS fluorescence intensity significantly increased, as compared with both the native and the fully unfolded states. The first refolding intermediate at the range of 0.8–1.0 mol GuHCl/L concentration represented a typical "pre-molten globule state structure" with inactivity. The second one, at the range of 0.3–0.5 mol GuHCl/L concentration, shared many structural characteristics of native AK, including its secondary and tertiary structure, and regained its catalytic function, although its activity was lower than that of native AK. The present results suggest that during the refolding of GuHCl-denatured AK there are at least 2 refolding intermediates; as well, the results provide direct evidence for the hierarchical mechanism of protein folding.Key words: arginine kinase, guanidine-denatured, refolding, intermediate, molten globule state.