bluuebunny/crossref_metadata_2025 huggingface dataset:
Wetting and Melt Extraction Characteristics of ZrO2–Al2O3 Based Materials
Authors: Allahverdi Mehdi , Drew Robin A. L. , Strom–Olsen John O.
Published: February 2007

A melt extraction technique has been used to produce fine fibers from three eutectic compositions in the systems of ZrO2‐Al2O3 (ZA), ZrO2‐Al2O3‐SiO2 (ZAS), and ZrO2‐Al2O3‐TiO2 (ZAT). The liquid surface tension of these ceramics was measured by a new method and estimated to be in the range of 400‐567 mJ/m2 at similar ∼2400°C. The wetting between Mo (the extraction wheel material) and liquid ceramics was found to be poor during transient wetting; however, fiber extraction was achieved due to the shear action induced by the wheel rotation. The difficulties in the extraction of ZA fibers at speeds of <1.5 m/s, and also the formation of air pockets on these fibers, are attributed to the poor wetting of the Mo wheel by the liquid ZA. In a wide range of wheel velocities, extracted fibers exhibited alternating sections of uniform diameter and Rayleigh waves, both being the largest for ZAS fibers at any speed. The Rayleigh wave dimensions varied considerably with speed whereas the dimensions of the uniform region of the fibers remained unchanged over the wide range of extraction speeds examined. The fiber dimensions are controlled by both surface tension and viscosity of the molten ceramics at the extraction temperature.
Internal Friction/Attenuation in a β‐Spodumene Glass‐Ceramic
Authors: Lee Jeffrey A. , Cooper Reid F.
Published: February 2007

Transient creep and attenuation (internal friction) of a β‐spodumene glass‐ceramic has been examined. Four‐point flexural creep tests have been performed at high tempera‐ture(T = 925°‐1000°C) and modest stress levels (σl,max= 7‐25 MPa). The flexural creep response of the glass‐ceramic is characterized by a large decelerating transient that precedes the establishment of a steady state. The creep response is transformed via a numerical algorithm to give the attenuation spectrum. In addition, low‐stress (2.5‐30 MPa), subresonant‐frequency (10 −5 Hz ≤ f ≤ 1 Hz), com‐pression‐compression attenuation experiments have been performed. A first‐order thermodynamic analysis of the effect of effective pressure on the volume fraction of re‐sidual glass suggests that the dilatational process that is associated with the flexural deformation mode should be characterized by a single loss mechanism. The predictions that are available from the flexural creep tests, as well as those that have been directly measured in experiments, in‐dicate that attenuation behavior is insensitive to both fre‐quency and temperature and exhibits a characteristic band of absorption. The weak frequency dependence of this an‐elastic response is well‐characterized by a power law of the form Q−1χfα, where 0.15 ≥ a ≥ 0.3, which suggests a physical mechanism that possesses a distribution of relax‐ation times. A plausible explanation exists in the fluid‐mechanics description of deformation‐induced melt migra‐tion, in which the crystalline β‐spodumene “matrix” undergoes compaction or dilatation while the residual glass phase, which forms an interpenetrative network along grain triple junctions of the matrix, flows: the evolution with time of the compacted (and/or dilated) layer thickness of the deforming matrix produces a distribution of compli‐ances.
Domain Growth in Pb(Mg1/3Ta2/3)O3 Perovskite Relaxor Ferroelectric Oxides
Authors: Akbas Mehmet A. , Davies Peter K.
Published: February 2007

Extensive studies that have been conducted on the Pb(Mg1/3Nb2/3)O3 (PMN) family of relaxor ferroelectrics have led to the establishment and acceptance of the“space‐charge” model as a basis for explaining their structures and dielectric properties. In this model, the arrangement of the metal cations on the octahedral sites of the perovskite structure is interpreted in terms of the formation of nega‐tively charged ordered nanodomains that are dispersed in a positively charged disordered matrix. The primary experi‐mental support for this interpretation has come from the apparent absence of any growth of the domains or change in the degree of ordering as the heat treatment is extended. Here, we report on experiments that have been conducted on the tantalate relaxor, Pb(Mg1/3Ta2/3)O3(PMT), and its solid solutions with PbZrO3, in which the size of the do‐mains and the degree of cation ordering have been in‐creased by two orders of magnitude through annealing that has been conducted at a temperature of 1325°C. Moreover, fully ordered ceramics that are comprised of large domains retain relaxor behavior. These results cannot be explained by the space‐charge model and support a charge‐balanced, “random‐site” model for the ordering of the metal cations
Detection of Minor Crystalline Phases in Alumina Ceramics Using Synchrotron Radiation Diffraction
Authors: Latella Bruno A. , O'Connor Brian H.
Published: February 2007

The use of synchrotron radiation diffraction (SRD) in con‐junction with conventional laboratory X‐ray diffraction (XRD) for analyzing the phase assemblage of selected alu‐mina‐based ceramics is described. This paper outlines the benefits of synchrotron powder diffraction in resolving mi‐norand impurity phases in various alumina ceramics. Laboratory XRD is shown to provide only cursory details of minor crystalline phases which are strikingly evident and clearly defined from application of SRD analysis. The po‐tential of SRD techniques to characterize low‐level crystal‐line phases and as a check for “phase purity” in ceramic systems is considered.
Manufacturing Nano‐Diphasic Materials from Natural Dolomite: In Situ Observation of Nanophase Formation Behavior
Authors: Suzuki Yoshikazu , Morgan Peter E. D. , Sekino Tohru , Niihara Koichi
Published: February 2007

Decomposition of the mixed carbonate mineral dolomite, CaMg(CO3)2, and formation of CaO/MgO nanopolycrystals were observed in situ using a field emission scanning electron microscope with a hot stage. The pyrolysis behavior of dolomite was studied with an in situ high–temperature X–ray powder diffraction technique. Nano–sized particles formed during pyrolysis then sintered into CaO/MgO nanopolycrystals. Dense bulk–form CaO/MgO and CaZrO3/MgO nanocomposites were successfully fabricated using reactive hot–pressing from dolomite and dolomite/zirconia mixed powders, respectively.
Synthesis of Perovskite‐Type Lanthanum Iron Oxide by Glycothermal Reaction of a Lanthanum–Iron Precursor
Authors: Kominami Hiroshi , Inoue Hiroaki , Konishi Shunsuke , Kera Yoshiya
Published: February 2007

Perovskite‐type lanthanum iron oxide (LaFeO3) powders were synthesized by glycothermal reaction at 300°C of a precursor that had been previously prepared by solvothermal decomposition of a mixture of lanthanum(III) isopropoxide and iron(III) butoxide (or methoxide) in toluene. Direct glycothermal reaction of the mixture yielded no double oxide, indicating that preparation of the precursor was important for crystallization of LaFeO3 by the glycothermal method.
Aqueous Processing and Stabilization of Manganese Zinc Ferrite Powders via a Passivation–Dispersion Approach
Authors: Mandanas Michael M. , Shaffer Walter , Adair James H.
Published: February 2007

A dispersion scheme for aqueous processing of manganese zinc ferrite suspensions is presented. The addition of oxalic acid leads to the formation of a uniform negative charge on the surface such that a cationic polyelectrolyte, polyethyleneimine (PEI), adsorbs and provides electrosteric dispersion. At 0.5 w/w (weight percent with respect to the dry powder) oxalic acid addition, there is a relatively uniform negative surface charge (approximately −30 mV) within the suspension pH range investigated (3–10), eliminating the isoelectric point (pH ∼7.6) present for the as‐received metal oxide powder. At the addition of 0.5 w/w PEI on an oxalate‐treated surface, the surface charge is constant and positive (∼20 mV) through a wide pH range, ∼5–10. The resulting rheological data for passivation–dispersion of relatively high‐solids manganese zinc ferrite suspensions (∼80 wt%) demonstrate improved colloid stability with improved rheological properties. The resulting apparent viscosity and Bingham yield point is 0.01 Pa·s (12.0 cP) and 0.24 Pa (2.4 dynes/cm2), respectively. A sulfonated napthalene‐based dispersant, typically used in industry, gives an apparent viscosity and Bingham yield point of 0.03 Pa·s (32 cP) and 3.1 Pa (31 dynes/cm2), respectively.
Electrophoretic Deposition Behavior of Aqueous Nanosized Zinc Oxide Suspensions
Authors: Tang Fengqiu , Uchikoshi Tetsuo , Sakka Yoshio
Published: February 2007

The rheological behavior and electrophoretic deposition (EPD) of ZnO nanopowder (nano‐ZnO) in aqueous media have been described. A cationic polyelectrolyte (polyethylenimine, PEI) was used to disperse and modify the surfaces of the ZnO nanoparticles. The rheological properties of the ZnO aqueous suspension were investigated by measuring the viscosity versus the pH and amount of dispersant. The EPD processing was conducted via cathodic electrodeposition, using stable suspensions with low viscosity, and the depositional behavior was investigated. Bubble‐free nano‐ZnO deposits with uniform microstructures were successfully obtained, which was an indication of good sintering behavior.
Solid‐State Synthesis of LaCoO3 Perovskite Nanocrystals
Authors: Li Feng , Yu Xianghua , Chen Liying , Pan Hongjun , Xin Xinquan
Published: February 2007

A solid‐state reaction process has been developed to synthesize perovskite‐type LaCoO3 nanocrystals with grain diameters of 15–40 nm. In the first step of the preparation, ∼5 nm composite hydroxide nanoparticles are synthesized by the solid‐state reaction of La(NO3)3·nH2O and Co(NO3)2·6H2O with KOH at ambient temperature. A perovskite‐type rhombohedral LaCoO3 phase appears at 550°C, after the hydroxide has been calcined at various temperatures. The phase transformation process is complete at ∼800°C, yielding a single‐phase binary oxide. The results indicate that the new process is convenient, inexpensive, and effective for obtaining LaCoO3 nanocrystals with high yield.
Pyrolysis Kinetics for the Conversion of a Polymer into an Amorphous Silicon Oxycarbide Ceramic
Authors: Sorarù Gian Domenico , Pederiva Luca , Latournerie Jérôme , Raj Rishi
Published: February 2007

We present experimental and analytical results for the pyrolysis reactions underlying the conversion of a cross‐linked polymer into an amorphous ceramic material. The activation energies, obtained from thermogravimetric data, and chemical analysis of the volatiles by mass spectroscopy are used to identify the reaction pathways. The reaction is determined to be first‐order, which is consistent with its solid‐state nature. The magnitude of the weight loss is analyzed to calculate the number of molecular sites in the polymer that participate in the reaction. The experiments were conducted on a polymer made from silsesquioxanes that convert into silicon oxycarbide ceramics on pyrolysis. The results show that <2.5% of the silicon atoms in the polymer are removed as volatile silanes, and less than one‐half of the carbon atoms are lost as methane. These results are a first step in understanding the molecular basis for the ceramic yield, as well as the evolution of the nanostructure as the material changes from an organic into a ceramic state by reactions that can occur at <850°C.
Novel Synthesis of Silica‐Coated Ferrite Nanoparticles Prepared Using Water‐in‐Oil Microemulsion
Authors: Tago Teruoki , Hatsuta Takatoshi , Miyajima Kanta , Kishida Masahiro , Tashiro Shizuka , Wakabayashi Katsuhiko
Published: February 2007

Ferrite nanoparticles (magnetite (Fe3O4) and cobalt‐ferrite (CoxFe3−xO4)) coated with silica (SiO2) were prepared using water‐in‐oil microemulsion of a polyoxyethylen(15)cetylether/cyclohexene system. Observation via transmission electron microscopy revealed that the ferrite nanoparticles were located nearly at the center of spherical SiO2 particles. The sizes of Fe3O4 and CoxFe3−xO4 nanoparticles were in the range of 8–12 nm and 10–14 nm, respectively, and the thickness of the SiO2 layer was ∼14.0 nm. The solid solution of cobalt ions into Fe3O4 to form CoxFe3−xO4 nanoparticles led to an increase in the coercivity of the SiO2‐coated ferrite nanoparticles. The coercivity increased with increasing amounts of added cobalt, obtaining a maximum value of 780 Oe around a Co/Fe ratio of 0.3–0.4.
Advances in the Modeling and Measurement of Drained Compressibility
Authors: Garcia Victor J. , Schilling Christopher H.
Published: February 2007

We have re‐examined the analysis of centrifugal consolidation experiments for the determination of drained compressibility. Existing models for centrifugation of ceramic powder suspensions are prone to error, because they do not fully account for spatial variations of both the centrifugal acceleration and packing density. We present a new model that accounts for these two effects. We also derive dimensionless parameters that separately describe the error contributions that result from the heterogeneities of both the centrifugal acceleration and packing density. These dimensionless parameters make it no longer necessary to determine drained compressibility by the complicated method of nondestructively measuring the density profiles of centrifuge cakes and then substituting these profiles into a complex mathematical equation that is difficult to solve. Instead, one can evaluate drained compressibility by applying a correction factor to a simple experimental method of measuring the cake height during multispeed centrifugation. In turn, this procedure provides a valuable, new tool to characterize the effects of ceramic processing variables on their tendency to produce density gradients during powder consolidation.
Low‐Temperature Sintering and Microwave Dielectric Properties of Anorthite‐Based Glass‐Ceramics
Authors: Lo Chung‐Lun , Duh Jenq‐Gong , Chiou Bi‐Shiou , Lee Wen‐Hsi
Published: February 2007

TiO2 nucleated anorthite‐based glass‐ceramics were fabricated from glass powders. After sintering and crystallization heat treatment, various physical properties, including apparent bulk density and water absorption, were examined to evaluate the sintering behavior of anorthite‐based glass‐ceramic. Results showed that the complete‐densification temperature for specimens was as low as 900°C. Sufficient crystallization was achieved by subsequently raising the firing temperature to 950°C, and the dielectric quality factor was promoted to the maximum value. Contents of nucleating agent (TiO2) played an important role in the dielectric constants. The crystallinity was controlled by raising the firing temperature at a constant heating rate. The degree of crystallization affected the dielectric properties of sintered glass‐ceramics. At the resonant frequency of 10 GHz, anorthite glass‐ceramics with 5 wt% TiO2 possessed the lowest permittivity of 8 and exhibited appropriate dielectric properties as compared with those with B2O3 and 10 wt% TiO2.
Kinetics of Slag Hydration in the Presence of Calcium Hydroxide
Authors: Biernacki J. J. , Richardson J. M. , Stutzman P. E. , Bentz D. P.
Published: February 2007

The reaction between ground granulated blast furnace slag (GGBFS) having an empirical formula of C7.88S7.39M3A and calcium hydroxide (CH) was investigated. The kinetics of the reaction were explored. Thermogravimetric analysis was used to monitor the consumption of CH from which rate constants were determined. Based on Knudsen's kinetic model, activation energies of 14.5, 17.9, and 22.6 kJ/mol were determined for three different mass ratios of slag and CH reacted over a temperature range of 15° to 50°C and hydrated for a period of time from 0 to 32 days. A comparison of the kinetics of the slag/CH reaction was made with slag/portland cement hydration. The basic features of both appear similar.
Crack‐Healing Behavior of Si3N4/SiC Ceramics under Cyclic Stress and Resultant Fatigue Strength at the Healing Temperature
Authors: Ando Kotoji , Takahashi Koji , Nakayama Shin , Saito Shinji
Published: February 2007

Si3N4/SiC composite ceramics were sintered and subjected to three‐point bending. A semi‐elliptical surface crack of 100 μm surface length was made on each specimen. The crack‐healing behavior under cyclic stress of 5 Hz, and resultant cyclic fatigue strengths at healing temperatures of 1100° and 1200°C, were systematically investigated. The main conclusions are as follows: (1) Si3N4/SiC composite ceramics have an excellent ability to heal a crack at 1100° and 1200°C. (2) This sample could heal a crack even under cyclic stress at a frequency of 5 Hz. (3) The crack‐healed sample exhibited quite high cyclic fatigue strength at each crack‐healing temperature, 1100° and 1200°C.
Effect of Heat Treatment on the Pore Structure and Drying Shrinkage Behavior of Hydrated Cement Paste
Authors: Thomas Jeffrey J. , Jennings Hamlin M.
Published: February 2007

The effect of a short heat treatment on hydrated cement paste has been investigated by measuring the weight and length changes of specimens as they undergo various combinations of heating, drying, and resaturation. Heating a cement paste to 60°C coarsens the capillary pore system, decreases the volume of mesopores, and increases the degree of polymerization of the silicates. In addition, the saturated weight of the paste is permanently decreased by a heat treatment. This weight loss can be explained by conversion of bound hydroxyl groups into liquid water during polymerization of the C‐S‐H gel phase. These experiments help reconcile and interpret published results describing the properties of cement cured at various temperatures, the effects of a short heat treatment on cement paste, and the thermal expansion behavior of saturated and dry cement paste.
Vaporization Studies of the La2O3–Ga2O3 System
Authors: Kuncewicz‐Kupczyk Wioletta , Kobertz Dietmar , Miller Miroslaw , Chatillon Christian , Singheiser Lorenz , Hilpert Klaus
Published: February 2007

The vaporization of the samples of the compositions Ga2O3+ LaGaO3, LaGaO3+ La4Ga2O9, and La4Ga2O9+ La2O3 was investigated using Knudsen effusion mass spectrometry in the temperature range 1494–1937 K. The partial pressures of the gaseous species O2, Ga, GaO, Ga2O, and LaO were determined over the samples investigated. The equilibrium partial pressures were used for the calculation of the thermodynamic activities of the components at 1700 K. Gibbs energies of formation of LaGaO3(s) and La4Ga2O9(s) at 1700 K from the component oxides were derived from the thermodynamic activities as −46.4 ± 4.7 and −99.2 ± 7.9 kJ·mol−1, respectively. The results were compared with the literature data obtained using other methods.
Effect of Grain Shape on Abnormal Grain Growth in Liquid‐Phase‐Sintered Nb1−xTixC–Co Alloys
Authors: Choi Kyoon , Hwang Nong M. , Kim Doh‐Y.
Published: February 2007

The effect of titanium substitution for niobium on the grain shape change, grain growth inhibition, and abnormal grain growth during liquid‐phase sintering of Nb1−xTixC–Co alloy was studied. With increased titanium substitution, the shape of the Nb1−xTixC grains in the liquid cobalt matrix was changed from a cube with round corners to a cube with angular corners, which implied increased edge energy. As the grain corners became more angular, the grain growth became markedly inhibited, and abnormal grain growth occurred. The results could be best explained by the increased edge energy of the interface of the Nb1−xTixC grains, which increased the barrier for the growth by two‐dimensional nucleation.
Effects of Octahedral Tilting on the Piezoelectric Properties of Strontium/Barium/Niobium‐Doped Soft Lead Zirconate Titanate Ceramics
Authors: Zheng Hong , Reaney Ian M. , Lee William E. , Jones N. , Thomas Howard
Published: February 2007

(Pb1−x−ySrxBay)(Zr0.976−zTizNb0.024)O3 solid solutions have been investigated to understand the relationship between structural changes caused by isovalent strontium and barium substitution on the A‐site and dielectric and piezoelectric properties. As strontium and barium were substituted for lead, the zirconium:titanium (Zr:Ti) ratio was modified so that all compositions had an optimized piezoelectric coefficient (d33). The value of d33 was at a maximum in the tetragonal phase near, but not at, the morphotropic‐phase boundary (MPB). The real MPB was taken as the Zr:Ti ratio at which X‐ray diffraction patterns appeared either pseudocubic or a mixture of rhombohedral and tetragonal. As strontium content increased, optimized d33 also increased from 410 pC/N (x= 0) to 640 pC/N (x= 0.12), commensurate with a decrease in the paraelectric‐to‐ferroelectric phase transition temperature (TC) from 350°C (x= 0) to 175°C (x= 0.12). However, for ceramics where x > 0.12, optimized d33 decreased even though the phase‐transition temperature was ∼150°C. Low strontium concentration ceramics (x= 0–0.08) contained 80 nm ferrroelectric domains typical of PZT, but high strontium concentration ceramics (x= 0.12–0.16) contained fine‐scale domains (20 nm) in some regions of the microstructure. In addition, [110] pseudocubic electron diffraction patterns revealed superlattice reflections at 1/2{hkl} positions associated with rotations of the octahedra in antiphase. Co‐doping ceramics with strontium (x= 0.06) and barium (y= 0.06) resulted in the disappearance of the 1/2{hkl} reflections. Optimized d33 (∼520 pC/N, TC∼ 205°C) for this composition was similar to that of ceramics where x= 0.08, y= 0, which had a TC of ∼250°C.
Spherical Yttrium Aluminum Garnet Embedded in a Glass Matrix
Authors: Nagashio Kosuke , Kuribayashi Kazuhiko
Published: February 2007

Containerless processing was used to investigate the glass‐forming behavior of Al2O3–Y2O3 glass. The amorphous bulk samples were obtained at compositions with 25–37.5 mol% yttria when the melt was cooled at a cooling rate of ∼250 K/s. Although small spherical particles (∼10 μm) with the same composition of the matrix were detected in the amorphous samples with 32.5–37.5 mol% yttria, the microfocus X‐ray diffraction result indicated that the small spherical particles were crystalline Y3Al5O12 garnet (YAG), rather than being amorphous. This observation suggested that small YAG particles could not grow larger after their nucleation, because of the high viscosity at high undercooling and the high cooling rate, which would graze the nose of the continuous cooling temperature diagram of YAG.
Aluminum Infiltration into Molybdenum Silicide Preforms
Authors: Bhattacharya Anup K. , Bhaskaran T. A. , Ramasesha Sheela K.
Published: February 2007

The presence of Mo5Si3 in MoSi2 preforms hinders the reactive infiltration of aluminum. To understand the role of Mo5Si3, the kinetics of aluminum infiltration into pure Mo5Si3 is studied. Irrespective of the initial composition (MoSi2 or Mo5Si3) of the preform, the final product always contains Mo(Al,Si)2. However, the aluminum content in the two cases is different: when the preform is MoSi2, the aluminum content is 14–18 at.%, and, when the preform is Mo5Si3, the aluminum content is 25–27 at.%. The activation energy for the reactive infiltration of aluminum into the Mo5Si3 preform is ∼26 kJ/mol.
Characterization and Investigation of the Tribological Properties of Sol–Gel Zirconia Thin Films
Authors: Chen Yunxia , Liu Weimin
Published: February 2007

Sol–gel zirconia thin films were prepared by dip coating in an ethanol solution of zirconium oxychloride. The zirconia films consisted of a completely tetragonal phase and exhibited nanoscale uniformity. They displayed excellent antiwear and friction‐reduction performance in sliding against steel. The friction coefficient (0.13–0.15) and the wear life over 5000 sliding cycles were recorded for the films at a sliding speed of 90 mm/min and a load of 0.5 N. The film was characterized by slight scuffing and abrasion at low loads and sliding speeds.
Electrical Characterization of a Joined Electroceramic, La0.85Sr0.15MnO3
Authors: Gutierrez‐Mora Felipe , Routbort Jules L.
Published: February 2007

Pieces of saw‐cut La0.85Sr0.15MnO3 were joined at 1150° and 1250°C under a compressive stress. The strains to form the joints were ∼0.1. Joints formed by plastic deformation were examined using scanning electron microscopy, and they were indistinguishable from the bulk. The room‐temperature direct‐current resistivity of the joined pieces was identical to that measured in the bulk material. This indicated that a sound, electrically conducting joint could be formed using plastic deformation (grain‐boundary sliding) with little surface preparation.
Reactive Ceria Nanopowders via Carbonate Precipitation
Authors: Li Ji‐Guang , Ikegami Takayasu , Wang Yarong , Mori Toshiyuki
Published: February 2007

Nanocrystalline CeO2 powders have been successfully synthesized via a carbonate precipitation method, using ammonium carbonate (AC) as the precipitant and cerium nitrate hexahydrate as the cerium source. The AC/Ce3+ molar ratio (R) affects significantly precursor properties, and spherical nanoparticles can be produced only in a narrow range of 2 < R≤ 3. The precursor, having an approximate composition of Ce(OH)CO3·2.5H2O, decomposes to CeO2 at temperatures ≥300°C. The CeO2 powder calcined at 700°C exhibits high reactivity and can be densified to >99% of theoretical at 1000°C.
pH Effect on Titania‐Phase Transformation of Precipitates from Titanium Tetrachloride Solutions
Authors: Sun Jing , Gao Lian
Published: February 2007

Precipitates in different structures were prepared by the hydrolysis of a TiCl4 solution at room temperature and 70°C. The pH effect on titania‐phase transformation was investigated. The original precipitate formed by the hydrolysis of titanium tetrachloride formed a gel‐like structure at pH 4 with the addition of NH4OH, which could be changed to essentially 100% rutile phase at 600°C. The rutile precipitates prepared at 70°C could be changed to mixed‐phase product at pH 0.50 and total anatase phase at pH 3.13 and 5.15. Complete phase transformation from anatase to rutile occurred in the three samples at 700°C.
Decrease in risk of lung cancer death in Japanese men after smoking cessation by age at quitting: Pooled analysis of three large‐scale cohort studies
Authors: Wakai Kenji , Marugame Tomomi , Kuriyama Shinichi , Sobue Tomotaka , Tamakoshi Akiko , Satoh Hiroshi , Tajima Kazuo , Suzuki Takaichiro , Tsugane Shoichiro
Published: February 2007

To evaluate the impact of smoking cessation on individuals and populations, we examined the decrease in risk of lung cancer death in male ex‐smokers by age at quitting by pooling the data from three large‐scale cohort studies in Japan. For simplicity, subjects were limited to male never smokers and former or current smokers who started smoking at ages 18–22 years, and 110 002 men aged 40–79 years at baseline were included. During the mean follow‐up of 8.5 years, 968 men died from lung cancer. The mortality rate ratio compared to current smokers decreased with increasing attained age in men who stopped smoking before age 70 years. Among men who quit in their fifties, the cohort‐adjusted mortality rate ratios (95% confidence interval) were 0.57 (0.40–0.82), 0.44 (0.29–0.66) and 0.36 (0.13–1.00) at attained ages 60–69, 70–79 and 80–89 years, respectively. The corresponding figures for those who quit in their sixties were 0.81 (0.44–1.48), 0.60 (0.43–0.82) and 0.43 (0.21–0.86). Overall, the mortality rate ratio for current smokers, relative to non‐smokers, was 4.71 (95% confidence interval 3.76–5.89) and those for ex‐smokers who had quit smoking 0–4, 5–9, 10–14, 15–19, 20–24 and ≥25 years before were 3.99 (2.97–5.35), 2.55 (1.80–3.62), 1.87 (1.23–2.85), 1.21 (0.66–2.22), 0.76 (0.33–1.75) and 0.67 (0.34–1.32), respectively. Although earlier cessation of smoking generally resulted in a lower rate of lung cancer mortality in each group of attained age, the absolute mortality rate decreased appreciably after stopping smoking even in men who quit at ages 60–69 years. (Cancer Sci 2007; 98: 584–589)
Meat, fish and fat intake in relation to subsite‐specific risk of colorectal cancer: The Fukuoka Colorectal Cancer Study
Authors: Kimura Yasumi , Kono Suminori , Toyomura Kengo , Nagano Jun , Mizoue Tetsuya , Moore Malcolm A. , Mibu Ryuichi , Tanaka Masao , Kakeji Yoshihiro , Maehara Yoshihiko , Okamura Takeshi , Ikejiri Koji , Futami Kitaroh , Yasunami Yohichi , Maekawa Takafumi , Takenaka Kenji , Ichimiya Hitoshi , Imaizumi Nobutoshi
Published: February 2007

High intake of red meat has been associated with increased risk of colorectal cancer in Western countries. There has been much interest in the role of n‐3 polyunsaturated fatty acids (PUFA) in colorectal cancer prevention, but epidemiological findings are limited and inconsistent. The objective of our study was to examine associations of meat, fish and fat intake with risk of colorectal cancer, paying particular attention to the subsite within the colorectum. Data were from the Fukuoka Colorectal Cancer Study, a population‐based case‐control study, covering 782 cases and 793 controls. Diet was assessed by interview, using newly developed personal‐computer software for registering semiquantitative food frequencies. The intake of beef/pork, processed meat, total fat, saturated fat or n‐6 PUFA showed no clear association with the overall or subsite‐specific risk of colorectal cancer. There was an almost significant inverse association between n‐3 PUFA and the risk of colorectal cancer; the covariate‐adjusted odds ratio for the highest (median 3.94 g/day) versus lowest (median 1.99 g/day) quintile of energy‐adjusted intake was 0.74 (95% confidence interval 0.52–1.06, trend P = 0.050). The consumption of fish and fish products was similarly inversely related to the risk although the association was not statistically significant. These associations were more evident for distal colon cancer; adjusted odds ratio for the highest versus lowest quintile of n‐3 PUFA intake was 0.56 (95% confidence interval 0.34–0.92, trend P = 0.02). Our findings do not support the hypothesis that consumption of red meat increases colorectal cancer risk but do suggest that high intake of fish may decrease the risk, particularly of distal colon cancer. (Cancer Sci 2007; 98: 590–597)
Polymerase chain reaction‐based fluorescent Luminex assay to detect the presence of human papillomavirus types
Authors: Oh Yongtaek , Bae Su Mi , Kim Yong‐Wan , Choi Ho‐Sun , Nam Gye‐Hyun , Han Se‐Jun , Park Choong Hak , Cho Younglae , Han Byoung‐Don , Ahn Woong Shick
Published: February 2007

Becuase 40% of human papillomavirus (HPV) infections are mixed infections, the accurate identification of high‐risk HPV genotypes in mixed infections is important for defining a woman's risk for progression to cervical cancer. Thus, advanced Luminex‐based HPV genotyping has been developed to simultaneously detect the presence of multiple HPV types. Here, we describe the development of a Luminex‐based HPV genotyping that combines polymerase chain reaction amplification with hybridization to fluorescence‐labeled polystyrene bead microarrays (Luminex suspension array technology). New HPV type‐specific oligonucleotide probes and YBT L1/GP6‐1 primers were used to detect the HPV types in 132 clinical samples. We simultaneously evaluated the usefulness of this technique on clinical samples. We detected 15 specific HPV types (6, 16, 18, 31, 35, 42, 51, 52, 55, 56, 58, 59, 66, 67 and 68) examined with specificity without known cross‐reaction to other HPV types. The detection limit for the different HPV types was above 500 plasmids. We compared the performance of the Luminex‐based assay to the established HPV DNA microarray chip for polymerase chain reaction products derived from 53 clinical samples. The evaluation showed excellent agreement. The Luminex‐based HPV genotyping was a sensitive, reproducible technique for the simultaneous genotyping of all clinically relevant genital HPV types. This assay system may be used to provide critical clinical information for early detection of HPV, especially in cases where the HPV copy numbers are low and the latency period of HPV infection is prolonged. (Cancer Sci 2007; 98: 549–554)
Metabolic characteristics of women with polycystic ovaries and oligo‐amenorrhoea but normal androgen levels: implications for the management of polycystic ovary syndrome
Authors: Barber Thomas M. , Wass John A. H. , McCarthy Mark I. , Franks Stephen
Published: February 2007

Objective  Application of the newly introduced Rotterdam criteria for polycystic ovary syndrome (PCOS) generates four phenotypic subgroups, defined by the presence/absence of three diagnostic elements: polycystic ovarian (PCO) morphology (P); hyperandrogenism (H); and oligo‐amenorrhoea (O). Whilst PCOS is associated with adverse metabolic features, the strength of the association within individual subgroups is not established. We characterized the metabolic and endocrine profiles of PCOS women who are oligomenorrhoeic but normoandrogenaemic, and compared these to other PCOS women and controls.

Design  Retrospective dataset analyses.

Patients  A total of 309 Europid PCOS women, all with PCO morphology, of whom 191 were also hyperandrogenaemic and oligomenorrhoeic (PHO), 76 hyperandrogenaemic with normal menses (PH) and 42 oligomenorrhoeic but normoandrogenaemic (PO); plus 76 Europid control women without PCOS.

Measurements  Metabolic parameters: fasting insulin, lipids, homeostasis model assessment (HOMA) measures of insulin sensitivity; endocrine variables: LH, FSH; prevalence of metabolic syndrome.

Results  Insulin sensitivity: PO women were indistinguishable from controls, and markedly less insulin‐resistant than PHO women (vs. controls, P = 0·38 after adjustment for BMI and age; vs. PHO, P = 0·003). Metabolic syndrome: the prevalence in PO women (7·1%) was similar to that in controls (3·9%), and lower than in PHO women (29·3%, P < 0·0001). LH levels: PO women were intermediate between controls (vs. controls, P = 0·008) and PHO women (vs. PHO, P = 0·06).

Conclusions  Normoandrogenaemic, oligomenorrhoeic women with PCOS are metabolically similar to control women with significantly fewer metabolic features than PCOS women who are also hyperandrogenaemic. However, higher than normal LH and lower sex hormone‐binding globulin (SHBG) concentrations in the PO women support the view that they form part of the spectrum of PCOS.
Primary aldosteronism: renaissance of a syndrome
Authors: Young William F.
Published: February 2007

Great strides have been made in our understanding of the pathophysiology of primary aldosteronism syndrome since Conn's description of the clinical presentation of a patient with an aldosterone‐producing adenoma (APA) more than 50 years ago. It is now recognized that the APA is just one of the seven subtypes of primary aldosteronism. APA and bilateral idiopathic hyperaldosteronism (IHA) are the most common subtypes of primary aldosteronism. Although most clinicians had thought primary aldosteronism to be a rare form of hypertension for more than three decades, it is now recognized to be the most common form of secondary hypertension. Using the plasma aldosterone to plasma renin activity ratio as a case‐finding test, followed by aldosterone suppression confirmatory testing, has resulted in much higher prevalence estimates of 5–13% of all patients with hypertension. In addition, there has been a new recognition of the aldosterone‐specific cardiovascular morbidity and mortality associated with aldosterone excess. Although thought to be daunting and complex in the past, the diagnostic approach to primary aldosteronism is straightforward and can be considered in three phases: case‐finding tests, confirmatory tests and subtype evaluation tests. Patients with hypertension and hypokalaemia (regardless of presumed cause), treatment‐resistant hypertension (three antihypertensive drugs and poor control), severe hypertension (≥ 160 mmHg systolic or ≥ 100 mmHg diastolic), hypertension and an incidental adrenal mass, onset of hypertension at a young age or patients being evaluated for other forms of secondary hypertension should undergo screening for primary aldosteronism. In patients with suspected primary aldosteronism, screening can be accomplished by measuring a morning (preferably between 0800 and 1000 h) ambulatory paired random plasma aldosterone concentration (PAC) and plasma renin activity (PRA). An increased PAC:PRA ratio is not diagnostic by itself, and primary aldosteronism must be confirmed by demonstrating inappropriate aldosterone secretion. Aldosterone suppression testing can be performed with orally administered sodium chloride and measurement of urinary aldosterone or with intravenous sodium chloride loading and measurement of PAC. Unilateral adrenalectomy in patients with APA or unilateral adrenal hyperplasia results in normalization of hypokalaemia in all these patients; hypertension is improved in all and is cured in approximately 30–60% of them. In bilateral adrenal forms of primary aldosteronism, unilateral or bilateral adrenalectomy seldom corrects the hypertension and they should be treated medically with a mineralocorticoid receptor antagonist.
Circulating obestatin levels in normal subjects and in patients with impaired glucose regulation and type 2 diabetes mellitus
Authors: Qi Xiaoya , Li Ling , Yang Gangyi , Liu Jianlei , Li Ke , Tang Yi , Liou Hua , Boden Guenther
Published: February 2007

Background  Obestatin is a novel hormone that is encoded by the Ghrelin gene and produced in the gut. Ghrelin is profoundly orexogenic and adipogenic, increasing food intake and body weight. This new ghrelin‐associated peptide behaves as a physiological opponent of ghrelin in rodent animals, but its pathophysiological role in humans remains unknown

Objective  In this study we investigate whether plasma obestatin level is different in patients with impaired glucose regulation (IGR) and type 2 diabetes mellitus (T2DM).

Patients and measurements  Forty‐seven patients with T2DΜ, 30 subjects with IGR, and 38 sex‐ and age‐matched normal controls participated in the study. Plasma obestatin levels were measured with a radioimmunoassay. The relationship between plasma obestatin levels and anthropometric and metabolic parameters was also analysed.

Results  Plasma obestatin levels were lower in patients with T2DM and IGR than in controls (37·5 ± 9·2 ng/l and 39·2 ± 9·7 ng/l vs. 43·8 ± 8·0 ng/l, P = 0·002 and P = 0·039, respectively). Decreasing concentrations of obestatin were independently and significantly associated with IGR and T2DM. Multiple logistic regression analysis revealed obestatin to be independently associated with IGR and T2DM. In a multiple linear regression analysis, only waist‐to‐hip ratio and homeostasis model assessment of insulin resistance (HOMA‐IR) were independently associated with plasma obestatin level.

Conclusion  Our results suggest that obestatin may play a role in appetite regulation in patients with IGR and T2DM.
N‐terminal pro‐B‐type natriuretic peptide in patients with growth hormone disturbances
Authors: Andreassen Mikkel , Faber Jens , Vestergaard Henrik , Kistorp Caroline , Kristensen Lars Østergaard
Published: February 2007

Background  Acromegaly is associated with hypertrophic cardiomyopathy, hypertension and subsequent congestive heart failure. Impairment of cardiac function has also been associated with growth hormone deficiency (GHD). B‐type natriuretic peptides (BNPs) have emerged as strong diagnostic and prognostic risk markers. They are cardioprotective hormones that compensate heart disease by promoting natriuresis and modulation of cardiac hypertrophy in response to volume expansion and ventricular wall stretch.

Objective  To investigate N‐terminal pro‐BNP (NT‐proBNP) in patients with GH disturbances before and after treatment, and in healthy gender‐ and age‐matched controls.

Subjects and methods  Ten acromegalic patients (age 48 ± 12 years) and 10 patients with GHD (age 41 ± 14 years) were studied. None had symptoms or signs of cardiovascular disease except for hypertension. Serum NT‐proBNP was measured before and 3, 6, 12 and 24 months after treatment.

Results  Baseline NT‐proBNP was lower in acromegalic patients [median (interquartile range) 24·3 (17·8–33·0) pg/ml] than in 20 healthy matched controls [57·9 (35·4–92·2) pg/ml; P < 0·001]. NT‐proBNP increased during treatment (P = 0·002), concomitant with a decrease in IGF‐I (P < 0·001). After 3 months of treatment NT‐proBNP peaked, with a fourfold increase to 96·4 (57·8–113·2) pg/ml. NT‐proBNP did not differ in patients with GHD compared with controls (P = 0·19), and did not change during treatment (P = 0·39).

Conclusion  Untreated patients with acromegaly had low NT‐proBNP levels that increased fourfold after treatment. This is in contrast to other conditions with cardiac hypertrophy. Further studies are required to determine the significance of this novel finding in relation to acromegalic cardiac disease.
The influence of the route of oestrogen administration on serum levels of cortisol‐binding globulin and total cortisol
Authors: Qureshi Ayesha C. , Bahri Aman , Breen Louise A. , Barnes Sophie C. , Powrie Jake K. , Thomas Stephen M. , Carroll Paul V.
Published: February 2007

Objectives  Oral oestrogen preparations increase total cortisol concentration by increasing circulating cortisol‐binding globulin (CBG) levels. Transdermal oestrogen treatments are being used increasingly in clinical practice. These topical preparations may have less of an effect on CBG and hence on total serum cortisol levels by reducing hepatic oestrogen exposure. The purpose of this study was to compare the effects of oral and topical oestrogen treatments on CBG, total serum cortisol and salivary cortisol levels.

Design and Patients  This was a single‐centre, cross‐sectional study of 37 women aged 33 ± 6 years (mean ± SD). Fourteen women were using oral oestrogen therapy, eight were using transdermal therapy and 15 were oestrogen‐naïve control subjects.

Measurements  Following a screening visit, the subjects attended the endocrine investigation unit following an overnight fast. Blood and salivary samples were taken from 0830 to 0930 h between days 10 and 18 of the menstrual cycle (where appropriate).

Results  Total serum cortisol concentrations were 67% higher in those receiving oral oestrogen when compared to control subjects (660·9 ± 89·9 vs. 395·4 ± 53·2 nmol/l, P < 0·001). Values in those receiving transdermal oestrogen (334·7 ± 72·0 nmol/l) were no different from the control group. CBG levels were higher in those on oral oestrogen therapy (110·9 ± 19·6 mg/l, P < 0·001) when compared with either those on transdermal oestrogen (51·0 ± 5·4 mg/l) or the control population (49·0 ± 11·8 mg/l). Similar salivary cortisol concentrations were recorded in the three groups (controls 13·8 ± 2·6 nmol/l, oral oestrogen 15·5 ± 2·6 nmol/l, transdermal oestrogen 15·7 ± 3·9 nmol/l).

Conclusions  Oral oestrogen‐containing preparations increase total cortisol levels by increasing circulating CBG concentration. These effects were not seen in patients using transdermal oestrogen replacement. Although further studies are indicated, it is probably unnecessary to routinely discontinue transdermal oestrogen replacement when performing an assessment of the hypothalamic–pituitary–adrenal (HPA) axis or evaluating adequacy of hydrocortisone replacement.
Ontogeny of foetal exposure to maternal cortisol using midtrimester amniotic fluid as a biomarker
Authors: Sarkar P. , Bergman K. , Fisk N. M. , O’Connor T. G. , Glover V.
Published: February 2007

Objective  There is increasing evidence that antenatal stress has long‐lasting effects on child development, but there is less accord on the mechanisms and the gestational window of susceptibility. One possible mechanism is by foetal exposure to maternal cortisol. To explore this, we investigated the relationship between cortisol in maternal plasma and amniotic fluid, and any moderating influence of gestational age.

Patients and measurements  Two hundred and sixty‐seven women awaiting amniocentesis for karyotyping were studied. Samples were collected between 0900 and 1730 h. Gestational age was determined to the nearest day by ultrasound biometry and time of collection noted to the nearest 15 min. Total cortisol was measured by radioimmunoassay in paired amniotic fluid and maternal blood samples (n = 267) [gestation range 15–37 weeks, median 17 weeks (119 days)].

Results  Both maternal and amniotic fluid cortisol levels increased with gestation (r = 0·25, P < 0·001; r = 0·33 P < 0·001, respectively). Amniotic fluid cortisol was positively correlated with time of collection (r = 0·22, P < 0·001) and negatively with maternal age (r =−0·24, P < 0·001). There was a positive correlation between amniotic fluid cortisol with maternal plasma levels (r = 0·32, P < 0·001), which persisted after multivariate analysis controlling for gestation, time of collection and maternal age. The association appeared to be dependent on gestational age, being nonsignificant at 15–16 weeks’ gestation and increasing in strength thereafter.

Conclusion  This study shows a positive correlation between maternal and amniotic fluid cortisol levels, which becomes robust from 17 to 18 weeks onwards. The results provide support for the hypothesis that alterations in maternal cortisol may be reflected in amniotic fluid levels from this gestation.
Genetic diversity and historical population structure of Schizopygopsis pylzovi (Teleostei: Cyprinidae) in the Qinghai–Tibetan Plateau
Authors: QI DELIN , GUO SONGCHANG , ZHAO XINQUAN , YANG JIE , TANG WENJIA
Published: February 2007

1. Complete sequences of 1140 base pair of the cytochrome b gene from 133 specimens were obtained from nine localities including the inflow drainage system, isolated lakes and outflow drainage system in Qinghai–Tibetan Plateau to assess genetic diversity and to infer population histories of the freshwater fish Schizopygopsis pylzovi.

2. Nucleotide diversities (π) were moderate (0.0024–0.0045) in populations from the outflow drainage system and Tuosuo Lake, but low (0.0018–0.0021) in populations from Qiadam Basin. It is probable that the low intra‐population variability is related with the paleoenvironmental fluctuation in Qiadam Basin, suggesting that the populations from Qiadam Basin have experienced severe bottleneck events in history.

3. Phylogenetic tree topologies indicate that the individuals from different populations did not form reciprocal monophyly, but the populations from the adjacent drainages cluster geographically. Most population pairwise FST tests were significant, with non‐significant pairwise tests between Tuosu Lake and Tuosuo Lake in the north‐west of the Qinghai–Tibetan Plateau. Analysis of molecular variance (amova) indicates that the significant genetic variation was explained at the levels of catchments within and among, not among specific boundaries or inflow and outflow drainage systems.

4. The nested clade phylogeographical analysis indicates that historical processes are very important in the observed geographical structuring of S. pylzovi, and the contemporary population structure and differentiation of S. pylzovi may be consistent with the historical tectonic events occurred in the course of uplifts of the Qinghai–Tibetan Plateau. Fluctuations of the ecogeographical environment and major hydrographic formation might have promoted contiguous range expansion of freshwater fish populations, whereas the geological barriers among drainages have resulted in the fragmentation of population and restricted the gene flow among populations.

5. The significantly large negative Fs‐value (−24.91, P < 0.01) of Fu's Fs‐test and the unimodal mismatch distribution indicate that the species S. pylzovi underwent a sudden population expansion after the historical tectonic event of the Gonghe Movement.

6. The results of this study indicate that each population from the Qinghai–Tibetan Plateau should be managed and conserved separately and that efforts should be directed towards preserving the genetic integrity of each group.