bluuebunny/crossref_metadata_2025 huggingface dataset:
Commodity Spot Prices: An Exploratory Assessment of Market Structure and Forward‐Trading Effects
Authors: SLADE MARGARET E. , THILLE HENRY
Published: February 2006

We assess how characteristics of product and forward markets affect levels and volatilities of commodity spot prices. We examine (i) how product market structure and forward market trading affect spot market games, (ii) the links between product market structure and spot price stability, (iii) whether forward trading destabilizes spot prices, and (iv) how information arrival affects price volatility and the volume of trade. We find that market structure models of the price level but not of price stability receive support, that increased forward trading leads to lower prices, and that the relationship between trading and price instability is indirect via a common causal factor.
The Race to the Bottom, from the Bottom
Authors: CHAU NANCY H. , KANBUR RAVI
Published: February 2006

The dominant perspective in discussions of labour and environmental standards and globalization is that of North–South competition and its impact on Northern standards. This paper presents an alternative perspective, that of South–South competition to export to the North and its impact on Southern standards. It develops a simple model of Southern competition, and demonstrates that whether a Southern race to the bottom is possible depends intricately on the Northern demand curve, the size of large exporters relative to each other and the relative size of the competitive fringe of small exporters. The possibility that Northern trade protectionism may undermine Southern standards is also examined.
EVALUATING THE MORPHOSPECIES CONCEPT IN THE SELENASTRACEAE (CHLOROPHYCEAE, CHLOROPHYTA)1
Authors: Fawley Marvin W. , Dean Michelle L. , Dimmer Stephanie K. , Fawley Karen P.
Published: February 2006

Isolates of the genera Monoraphidium Kom.‐Legn., Ankistrodesmus Corda and Raphidocelis Hindák emend. Marvan et al. were cultured from two areas in Minnesota and North Dakota, USA. These isolates were identified to species level (when possible), using light microscopy and standard monographs and then characterized by 18S rDNA sequence analysis. Phylogenetic analyses indicated that in some cases, 18S rDNA sequences from these isolates were very similar, but not identical to the sequences of other isolates of the same morphospecies from different parts of the world. However, some isolates that were identified as the same species actually belong to different lineages within the Selenastraceae, whereas other isolates with identical or nearly identical 18S rDNA sequences possessed rather different morphologies. Overall, our data suggest that the application of a broad morphospecies concept to the Selenastraceae has resulted in an underestimation of the species diversity of this family and probably erroneous conclusions about the distribution of species.
AN EXPRESSED SEQUENCE TAG ANALYSIS OF THALLUS AND REGENERATING PROTOPLASTS OFCHONDRUS CRISPUS(GIGARTINALES, RHODOPHYCEAE)1
Authors: Collén Jonas , Roeder Vincent , Rousvoal Sylvie , Collin Olivier , Kloareg Bernard , Boyen Catherine
Published: February 2006

In order to identify genes involved in cell wall regeneration and stress responses in red algae, expressed sequence tags (ESTs) from protoplasts (2002 ESTs) and thalli (2052 ESTs) from the seaweedChondrus crispus(Stackh.) were studied. Clustering gave 2291 non‐redundant sequences; 50% of the ESTs showed similarity (e<10−4) to known sequences. The fraction of stress‐related ESTs was five‐times higher in the protoplast library than in the thallus library. The ESTs that were statistically over‐represented in protoplasts included: glutathione S‐transferases, heat shock proteins, vanadium bromoperoxidase, and several genes of unknown function; in all 32 transcripts. Over‐represented genes in thallus included: NADH dehydrogenase, a peroxidase, and several genes of unknown function; in all 12 transcripts. In general, the ESTs from the two libraries were very different; for example, only 38% of contigs had members of both catalogues. The approach allowed the identification of numerous stress genes; including 23 different heat shock proteins and molecular chaperones, antioxidative enzymes, and several genes potentially involved in detoxification. Genes potentially involved in the construction of the cell wall or the extracellular matrix included α‐galactosidase, pullulanase, sulfohydrolase, and several sequences with von Willebrand factor type A domains with similarities to cochlin, integrin, and vitrin.
ON THE IDENTITY OFKARLODINIUM VENEFICUMAND DESCRIPTION OFKARLODINIUM ARMIGERSP. NOV. (DINOPHYCEAE), BASED ON LIGHT AND ELECTRON MICROSCOPY, NUCLEAR‐ENCODED LSU RDNA, AND PIGMENT COMPOSITION1
Authors: Bergholtz Trine , Daugbjerg Niels , Moestrup Øjvind , Fernández‐Tejedor Margarita
Published: February 2006

An undescribed species of the dinoflagellate genusKarlodiniumJ. Larsen (viz.K. armigersp. nov.) is described from Alfacs Bay (Spain), using light and electron microscopy, pigment composition, and partial large subunit (LSU) rDNA sequence. The new species differs from the type species ofKarlodinium(K. micrum(Leadbeater et Dodge) J. Larsen) by lacking rows of amphiesmal plugs, a feature presently considered to be a characteristic ofKarlodinium. InK. armiger, an outer membrane is underlain by a complex system of cisternae and vacuoles. The pigment profile ofK. armigerrevealed the presence of chlorophyllsaandc, with fucoxanthin as the major carotenoid. Phylogenetic analysis confirmedK. armigerto be related to other species ofKarlodinium; thus forming a monophyletic genus, which, in the LSU tree, occupies a sister group position toTakayamade Salas, Bolch, Botes et Hallegraeff. The culture used by Ballantine to describeGymnodinium veneficumBallantine (Plymouth 103) was examined by light and electron microscopy and by partial LSU rDNA. Ultrastructurally, it proved identical toK. micrum(cultures Plymouth 207 and K. Tangen KT‐77D, the latter also known as K‐0522), and in LSU sequence, differed in only 0.3% of 1438 bp. We consider the two taxa to belong to the same species. This necessitates a change of name for the most widely found species,K. micrum, toK. veneficum. The three generaKarlodinium,Takayama, andKareniaconstitute a separate evolutionary lineage, for which the new family Kareniaceae fam. nov. is suggested.
PROPOSAL OF THE EUPTILOTEAE HOMMERSAND ET FREDERICQ, TRIB. NOV. AND TRANSFER OF SOME SOUTHERN HEMISPHERE PTILOTEAE TO THE CALLITHAMNIEAE (CERAMIACEAE, RHODOPHYTA)1
Authors: Hommersand Max H. , Freshwater D. Wilson , Lopez‐Bautista Juan M. , Fredericq Suzanne
Published: February 2006

Morphological and molecular studies demonstrate that the tribe Ptiloteae (Ceramiaceae, Ceramiales) is polyphyletic. The Ptiloteae,sensu stricto, occur only in the Northern Hemisphere and all Southern Hemisphere representatives belong in other tribes. Three genera (Euptilota,Seirospora, andSciurothamnion) are transferred to the Euptiloteae Hommersand et Fredericq, trib. nov., and the Callithamnieae is revised to include threePtilota‐like genera,Georgiella,Falklandiella, andDiapse, and two new genera.HeteroptilonHommersand, gen. nov. is erected to receiveEuptilota pappeanaKützing 1849 andAglaothamnion rigidulumDe Clerck, Bolton, Anderson et Coppejans 2004 from South Africa, andAristoptilonHommersand et W. A. Nelson, gen. nov. is established to receiveEuptilota mooreanaLindauer 1949 from New Zealand. The principal difference between the Euptiloteae and the Callithamnieae is seen in the earliest stages after fertilization. The fertilized carpogonium enlarges and forms a pair of tube‐like protuberances directed toward the auxiliary cells that are cut off as connecting cells in the Euptiloteae, whereas in the Callithamnieae the carpogonium usually divides into two cells, each of which cuts off a small connecting cell that fuses with an adjacent enlarging auxiliary cell. Nuclei are terminal in spermatangia of the Euptiloteae, subtended by mucilaginous vesicles, and are medial in the Callithamnieae situated between apical and basal vesicles. The Euptiloteae and Callithamnieae (including thePtilota‐like members) are each strongly supported in maximum‐likelihood tree topologies resulting from analyses of combined 18S rDNA, 28S rDNA, 16S rDNA, and rbcL data sets. Their sister relationship is also well supported.
EXPLORING THE NATURAL ROLE OF MICROCYSTINS—A REVIEW OF EFFECTS ON PHOTOAUTOTROPHIC ORGANISMS1
Authors: Babica Pavel , Bláha Luděk , Maršálek Blahoslav
Published: February 2006

Cyanobacterial blooms and the production of cyanotoxins represent a serious global problem. Although the effects of a group of important cyanotoxins, microcystins (MCs), have been studied intensively in various organisms, little is known about the natural functions of these cyclic heptapeptides. MCs may have allelopathic effects. This paper summarizes the information from the studies that have investigated the effects of MCs on photoautotrophs in vitro and in vivo. Interactions with terrestrial plants, macrophytes, macroalgae, and planktonic microalgae are reported in detail with respect to the ecological relevancy of experimental conditions related to allelopathy. Our review shows that only a limited number of studies described harmful effects of MCs at concentrations that are typical for the environment. Consequently, the ability of MCs to act as general allelopathic compounds against photoautotrophs seems unlikely. However, further research is needed for definitive confirmation or rejection of the allelopathic hypothesis as well as, an explanation of the crucial question of MC function in the context of new information from evolutionary and molecular biology.
BIOCHEMICAL PHENOTYPES CORRESPONDING TO MOLECULAR PHYLOGENY OF THE RED ALGAE PLOCAMIUM (PLOCAMIALES, RHODOPHYTA): IMPLICATIONS OF INCONGRUENCE WITH THE CONVENTIONAL TAXONOMY1
Authors: Yano Tomomi , Kamiya Mitsunobu , Murakami Akio , Sasaki Hideaki , Kawai Hiroshi
Published: February 2006

Among five species of the genus Plocamium Lamouroux distributed around Japan, P. cartilagineum (Linnaeus) Dixon, P. recurvatum Okamura and P. telfairiae (Hooker and Harvey) Harvey are often difficult to distinguish morphologically from each other. Our previous study demonstrated that P. recurvatum and P. telfairiae were divided into two groups, A and C, based on RUBISCO spacer sequence and that the specimens belonging to group C had acidic cell saps. In this study, we inferred evolutionary relationships of these Plocamium species from internal transcribed spacer sequence of the ribosomal RNA genes and obtained a similar topology to the RUBISCO spacer tree. Color of the dried specimens in the acidic group C was darker red than that in the non‐acidic group A, although there was no difference in color in living thalli. The Br− concentration in the cell sap of the acidic group C was 20 times higher than that of the non‐acidic group. We could not find any morphological differences to distinguish clearly between groups A and C despite exhaustive investigation of field‐collected and cultured thalli in both P. recurvatum and P. telfairiae. These results suggest that the color of dried specimens and the composition of intracellular inorganic ions are significant criteria for interpreting phylogenetic relationships in Japanese Plocamium spp.
The Columbia Cooperative Aging Program: An Interdisciplinary and Interdepartmental Approach to Geriatric Education for Medical Interns
Authors: Maurer Mathew S. , Costley Alex W. , Miller Patricia A. , McCabe Sigrid , Dubin Shelly , Cheng Huai , Varela‐Burstein Ellyn , Lam Binh , Irvine Craig , Page Kerrianne P. , Ridge Gerald , Gurland, MD Barry
Published: February 2006

Although there is a critical need to prepare physicians to care for the growing population of older adults, many academic medical centers lack the geriatric‐trained faculty and dedicated resources needed to support comprehensive residency training programs in geriatrics. Because of this challenge at Columbia University, the Columbia Cooperative Aging Program was developed to foster geriatric training for medical interns. For approximately 60 interns each year completing their month‐long geriatric rotations, an integral part of this training now involves conducting comprehensive assessments with “well” older people, supervised by an interdisciplinary team of preceptors from various disciplines, including cardiology, internal medicine, occupational therapy, geriatric nursing, psychiatry, education, public health, social work, and medical anthropology.

Interns explore individual behaviors and social supports that promote health in older people; older people's strengths, vulnerabilities, and risk for functional decline; and strategies for maintaining quality of life and independence. In addition, a structured “narrative medicine” writing assignment is used to promote the interns' reflections on the assessment process, the data gathered, and their clinical reasoning throughout. Preliminary measures of the program's effect have shown significant improvements in attitudes toward, and knowledge of, older adults as patients, as well as in interns' self‐assessed clinical skills. For academic medical centers, where certified geriatric providers are scarce, this approach may be an effective model for fostering residency geriatric education among interns.
Abdominal Obesity Is an Independent Risk Factor for Chronic Heart Failure in Older People
Authors: Nicklas Barbara J. , Cesari Matteo , Penninx Brenda W.J.H. , Kritchevsky Stephen B. , Ding Jingzhong , Newman Anne , Kitzman Dalane W. , Kanaya Alka M. , Pahor Marco , Harris Tamara B.
Published: February 2006

OBJECTIVES: To examine whether total and abdominal adiposity are risk factors for the development of chronic heart failure (CHF) in older men and women.

DESIGN: Prospective, longitudinal cohort: The Health, Aging and Body Composition study.

SETTING: Memphis, Tennessee, and Pittsburgh, Pennsylvania, metropolitan areas.

PARTICIPANTS: Three thousand seventy‐five well‐functioning community‐dwelling older adults aged 70 to 79.

MEASUREMENTS: Body composition using dual energy X‐ray absorptiometry, visceral adipose tissue area using computed tomography, adjudicated CHF.

RESULTS: Of the remaining (640 participants excluded from original group of 3,075) 2,435 participants (1,081 men, 1,354 women) without coronary heart disease or CHF at baseline, there were 166 confirmed diagnoses of CHF during the median±standard deviation (SD) follow‐up of 6.1±1.4 years. After adjustment for age, race, sex, site, education, smoking, and chronic obstructive pulmonary disorder, all adiposity variables (body mass index (BMI), adipose tissue mass, percentage body fat, waist‐to‐thigh ratio, waist circumference, and visceral and subcutaneous abdominal adipose tissue) were significant predictors of the development of CHF. In a model that included waist circumference and BMI, waist circumference was associated with incident CHF (hazard ratio (HR)=1.27, 95% confidence interval (CI)=1.04–1.54 per SD increase, P=.02), but BMI was not (HR=1.08, 95% CI=0.86–1.35). When waist circumference and percentage fat were included together, both variables were significant predictors of CHF (waist: HR=1.17, 95% CI=1.00–1.36 per SD increase, P=.05; percentage fat: HR=1.47, 95% CI=1.16–1.87 per SD increase, P=.002). Stepwise adjustment for inflammation, hypertension, insulin resistance, and diabetes mellitus did not decrease the relative risk of a greater waist circumference for the development of CHF (all HR=1.27–1.32, 95% CI=1.02–1.61 per SD increase).

CONCLUSION: Abdominal body fat distribution may be a stronger risk factor for CHF than overall obesity.
Executive Dysfunction in Homebound Older People with Diabetes Mellitus
Authors: Qiao Qiu Wei , Lyn Price Lori , Hibberd Patricia , Buell Jennifer , Collins Lauren , Leins Drew , Mkaya Mwamburi David , Rosenberg Irwin , Smaldone Lauren , Scott Tammy M. , Siegel Richard D. , Summergrad Paul , Sun Xiaoyan , Wagner Carey , Wang Lixia , Yee Jacqueline , Tucker Katherine L. , Folstein Marshal
Published: February 2006

OBJECTIVES: To describe patterns of cognitive deficits and activities of daily living (ADLs) in older people with diabetes mellitus.

DESIGN: Cross‐sectional, population‐based study.

SETTING: Three homecare agency areas in Boston, Massachusetts.

PARTICIPANTS: Two hundred ninety‐one homebound people aged 60 and older; 40% with diabetes mellitus.

MEASUREMENTS: Demographic data; evidence of diabetes mellitus and other diseases; Mini‐Mental State Examination and tests of memory and executive function; ADLs.

RESULTS: Executive and visuospatial functions were more impaired in individuals with diabetes mellitus than in those without, as assessed using Block Design (mean score±standard deviation 17.1±8.6 vs 20.5±9.6, P=.003) and Trails B (median seconds to accomplish the task: 255 vs 201, P=.03). For memory, word retention score was lower in those with diabetes mellitus than without (39.1±28.9 vs 48.0±29.7, P=.01), but the other memory tests did not show a difference between these two subgroups. More individuals with diabetes mellitus suffered from depressive symptoms than those without (55% vs 42%, P=.03). The ADL scores of those with diabetes mellitus were higher than those without.

CONCLUSION: The pattern of cognitive deficits in people with diabetes mellitus suggests frontal‐subcortical dysfunction, as seen in microvascular disease of the brain. The impairment in ADLs may be associated with this executive dysfunction, which cerebral microvascular disease in diabetes mellitus may cause.
Hydroxymethylglutaryl‐CoA Reductase Inhibitors in Older Persons with Acute Myocardial Infarction: Evidence for an Age–Statin Interaction
Authors: Micale Foody JoAnne , Rathore Saif S. , Galusha Deron , Masoudi Frederick A. , Havranek Edward P. , Radford Martha J. , Krumholz Harlan M.
Published: February 2006

OBJECTIVES: To characterize the relationship between hydroxymethylglutaryl‐CoA reductase inhibitors (statins) and outcomes in older persons with acute myocardial infarction (AMI).

DESIGN: Observational study.

SETTING: Acute care hospitals in the United States from April 1998 to June 2001.

PARTICIPANTS: Medicare patients aged 65 and older with a principal discharge diagnosis of AMI (N=65,020) who did and did not receive a discharge prescription for statins.

MEASUREMENTS: The primary outcome of interest was all‐cause mortality at 3 years after discharge.

RESULTS: Of 23,013 patients with AMI assessed, 5,513 (24.0%) were receiving a statin at discharge. Nearly 40% of eligible patients (n=8,452) were aged 80 and older, of whom 1,310 (15.5%) were receiving a statin at discharge. In a multivariable model taking into account demographic, clinical, physician and hospital characteristics, and propensity score, discharge statin therapy was associated with significantly lower 3‐year mortality (hazard ratio (HR)=0.89 (95% confidence interval (CI)=0.83–0.96)). In an analysis stratified by age, discharge statins were associated with lower mortality in patients younger than 80 (HR=0.84, 95% CI=0.76–0.92) but not in those aged 80 and older (HR=0.97, 95% CI=0.87–1.09).

CONCLUSION: Statin therapy is associated with lower mortality in older patients with AMI younger than 80 but not in those aged 80 and older, as a group. This finding questions whether statin efficacy data in younger patients can be broadly applied to the very old and indicates the need for further study of this group.
Is Hospice Associated with Improved End‐of‐Life Care in Nursing Homes and Assisted Living Facilities?
Authors: Munn Jean C. , Hanson Laura C. , Zimmerman Sheryl , Sloane Philip D. , Mitchell C. Madeline
Published: February 2006

OBJECTIVES: To examine whether hospice enrollment for nursing home (NH) and residential care/assisted living (RC/AL) residents near the end of life is associated with symptoms and symptom management, personal care, spiritual support, and family satisfaction.

DESIGN: Structured, retrospective telephone interviews with family and staff who attended to NH and RC/AL residents in the last month of life.

SETTING: A stratified sample of 26 NH and 55 RC/AL facilities in four states.

Participants: Family members (n=97) and long‐term care (LTC) staff (n=104) identified as most involved in care of 124 residents who died over a 15‐month period.

MEASUREMENTS: A variety of reported measures of care and symptoms before death, including the Discomfort Scale for Dementia of the Alzheimer's Type.

RESULTS: Of 124 decedents, 27 (22%) received hospice services. Dementia was less common in hospice enrollees than in decedents who did not receive hospice care. Hospice enrollees more often had moderate/severe pain and dyspnea and received pain treatment and were more likely to receive assistance with mouth care and eating and drinking. There were no differences related to unmet need, and observed differences were largely eliminated when comparisons were limited to residents whose deaths were expected.

CONCLUSION: Rates of hospice use observed in this study (22%) were considerably higher than previously reported, although persons with dementia may continue to be underreferred. Hospice use is targeted to dying residents with higher levels of reported pain and dyspnea. Because difference in care largely disappears in cases when death was expected, LTC staff seem to be well positioned to provide end‐of‐life care for their residents and are advised to remain sensitive to instances in which death may be expected.
Semiparametric Regression in Capture–Recapture Modeling
Authors: Gimenez O. , Crainiceanu C. , Barbraud C. , Jenouvrier S. , Morgan B. J. T.
Published: February 2006

SummaryCapture–recapture models were developed to estimate survival using data arising from marking and monitoring wild animals over time. Variation in survival may be explained by incorporating relevant covariates. We propose nonparametric and semiparametric regression methods for estimating survival in capture–recapture models. A fully Bayesian approach using Markov chain Monte Carlo simulations was employed to estimate the model parameters. The work is illustrated by a study of Snow petrels, in which survival probabilities are expressed as nonlinear functions of a climate covariate, using data from a 40‐year study on marked individuals, nesting at Petrels Island, Terre Adélie.
Smoothing Spline‐Based Score Tests for Proportional Hazards Models
Authors: Lin Jiang , Zhang Daowen , Davidian Marie
Published: February 2006

SummaryWe propose “score‐type” tests for the proportional hazards assumption and for covariate effects in the Cox model using the natural smoothing spline representation of the corresponding nonparametric functions of time or covariate. The tests are based on the penalized partial likelihood and are derived by viewing the inverse of the smoothing parameter as a variance component and testing an equivalent null hypothesis that the variance component is zero. We show that the tests have a size close to the nominal level and good power against general alternatives, and we apply them to data from a cancer clinical trial.
The Jolly–Seber Model with Tag Loss
Authors: Cowen Laura , Schwarz Carl J.
Published: February 2006

Summary Tag loss in mark‐recapture experiments is a violation of one of the Jolly–Seber model assumptions. It causes bias in parameter estimates and has only been dealt with in an ad hoc manner. We develop methodology to estimate tag retention and abundance in double‐tagging mark‐recapture experiments. We apply this methodology to walleyes (Stizostedion vitreum) in Mille Lacs, Minnesota.
Layer‐by‐Layer Self‐Assembly of Ceramic Particles for Coating Complex Shape Substrates
Authors: Qiu Hongwei , Lee Woo Y. , Sukhishvili Svetlana A.
Published: February 2006

Key parameters for controlling the layer‐by‐layer self‐assembly of ceramic particles were studied using a model system, which consisted of an Si substrate, 100 and 500 nm silica spheres, and a polycation/polyanion combination that provided binding between the substrate and silica particles, as well as between the silica particle layers. The overall quality of the particle assemblies was mainly dictated by (1) the degree of electrostatic attraction between the negatively charged silica particles and the outermost positively charged electrolyte layer of a polyelectrolyte multilayer and (2) electrostatically repulsive interactions between the silica particles. The surface coverage of the silica particles improved with an increase of NaCl used in deposition of the polyelectrolyte layers and silica particles, and with an increased number of the polyelectrolyte/particle layers deposited. We found that the effects of particle size, polydispersity, and electrolyte concentration in the particle suspension on the surface coverage and morphology of the first silica particle layer deposited on the polyelectrolyte layer surface were highly coupled, and resolution of these effects was important in generating a rational basis for infiltrating a uniform coating of multilayer silica particle assemblies into a cellular structure.
Improvement of the Dispersion of Al2O3 Slurries Using EDTA‐4Na
Authors: Zhang Jingxian , Xu Qiang , Tanaka Hideaki , Iwasa Mikio , Jiang Dongliang
Published: February 2006

Polyacrylic acid (PAA) is known to be an effective dispersant for Al2O3 powder in aqueous media. However, at high solid loading (>55 vol%), the dispersion of the Al2O3 suspensions became difficult with only PAA as a dispersant. In this paper, ethylenediaminetetraacetic acid, tetrasodium salt, dihydrate (EDTA‐4Na) was introduced to improve the dispersion of the Al2O3 suspensions. With the aid of EDTA‐4Na, the adsorption amount of sodium polyacrylic acid (PAA‐Na) increased, while the apparent viscosity of 60 vol% Al2O3 slurries decreased significantly. Particle size measurements showed that EDTA‐4Na could help to reduce larger agglomerates, possibly by modifying the adsorbed layer thickness. The interactions between EDTA‐4Na and PAA‐Na were studied using Fourier‐transform infrared spectroscopy analysis. Results showed that it was possible to introduce EDTA‐4Na as the second dispersant to improve the dispersion of high solid content Al2O3 slurries.
Effects of Heat Treatments in HCl on the Fiber Bundle Strength of a Two‐Phase Polycrystalline Oxide Fiber
Authors: Haslam Jeffery J. , Lange Frederick F.
Published: February 2006

The effects of heat treatments in air and in an HCl gas atmosphere on the strength of Nextel 720 fibers were investigated. These fibers were polycrystalline oxide fibers containing two phases: mullite and alumina. The fibers were heat treated in air and in HCl at 1200° and 1300°C for 1 h to simulate possible processing conditions for all‐oxide ceramic fiber composites. These fibers were tested as bundles containing approximately 400 fibers, as supplied by the manufacturer. Tests with fibers in the as‐received condition were also conducted for comparison. The as‐received fibers had a bundle strength of approximately 1 GPa. Most of the fiber heat treatments appear to cause modest reductions in the average strength, although there was scatter in the results. Fibers heat treated in HCl at 1300°C did not appear to show a statistically significant reduction in strength, and suggest the suitability of this process for strengthening an all‐oxide ceramic fiber composite. Examination of the fracture surfaces indicated that weld lines (at locations where the fibers were touching when the fibers were made) were the source of the critical flaws that caused fiber fracture. The possible effects of the heat treatments on the weld lines and the bundle strengths were discussed.
Analysis of Compositional Distributions for Exploring the Phase Space by the Single Sample Concept in Ceramic Combinatorial Chemistry
Authors: Hulliger Jürg , Dessauges Luc , Samtleben Till A.
Published: February 2006

Different components forming part of a local configuration of n≥2 grains constitute a phase system in which the locally available masses define a working point in the corresponding phase diagram. Because the number of configurations can be larger than the number of possible phase diagrams, a basic issue of the single sample concept (SSC) may be addressed by a statistical analysis: is the large phase space of possible compounds efficiently explored by the SSC? In the present study, the compositional distribution functions p(XE) were calculated for some of the N components comprising a sample. Broad p(XE) distributions were obtained using reasonable assumptions for the distributions describing the grain size and the local coordination number of grains. p(XE) functions were calculated both analytically and using a fully numerical procedure. Application of the method to cuprate superconductors revealed that the observed stoichiometries conformed well with the corresponding p(XE) distributions. From the present analysis we conclude that the SSC can provide starting compositions for compounds expected to be present in phase systems for given reaction conditions T and p.
Synthesis of Yttrium–Aluminum–Garnet Hollow Microspheres by Reverse‐Emulsion Technique
Authors: Chatterjee Minati , Naskar Milan Kanti
Published: February 2006

Yttrium–aluminum–garnet (YAG, Y3Al5O12) hollow microspheres were synthesized by reverse‐emulsion (w/o) technique starting with aqua‐based precursors of oxides. The non‐ionic surfactant was used as the emulsifying agent. The gel powders were calcined at 700°–1200°C. The synthesized powders were characterized by differential thermal analysis (DTA), thermogravimetry, Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), and scanning electron microscopy (SEM). The appearance of an exothermic peak at 932°C in the DTA curve revealed the crystallization of YAG, which was further confirmed by XRD and FTIR studies. SEM confirmed the formation of hollow microspheres.
Effects of Ethanol Addition and Ba/Ti Ratios on Preparation of Barium Titanate Nanocrystals Via a Spray Pyrolysis Method
Authors: Wang Wei‐Ning , Wuled Lenggoro I. , Okuyama Kikuo , Terashi Yoshitake , Wang Yu‐Cong
Published: February 2006

BaTiO3 nanocrystals were synthesized by using a low‐pressure spray pyrolysis (SP) method. A new strategy was proposed to improve nanocrystal formation and phase evolution by ethanol addition and Ba/Ti molar ratio variation, respectively. A mixture of submicron and nanoparticles was found with SP of precursors without ethanol addition, while only nanoparticles could be obtained by ethanol addition. BaTiO3 crystal growth was improved by increasing the Ba/Ti ratio. In comparison, SP of the same precursor under atmospheric conditions resulted in only submicron particles with smooth surfaces and irregular morphology.
A/B Site Modified CaTiO3 Dielectric Ceramics for Microwave Application
Authors: Liu Tao , Zhao Xing‐Zhong , Chen Wen
Published: February 2006

(Li1/2Nd1/2)2+ substitution into the A site and (Mg1/3Ta2/3)4+ substitution into the B site of CaTiO3 ceramic were investigated, respectively. The modified CaTiO3 dielectric ceramics prepared by conventional solid‐state method exhibit single perovskite structure and improved dielectric properties. Optimal microwave dielectric properties of ɛr=112.6, Q×f=4480 GHz, τf=8.2 ppm/°C in [Ca0.4(Li1/2Nd1/2)0.6] TiO3 and ɛr=60.2, Q×f=36900 GHz, τf=−10.1 ppm/°C in Ca[Ti0.4(Mg1/3Ta2/3)0.6] O3 are obtained, which indicates their potential for microwave application. The effects of change of crystal structure on dielectric properties are also discussed.
Piezoelectric Fibers with Uniform Internal Electrode by Co‐Extrusion Process
Authors: Yoon Chang‐Bun , Jun Shin‐Hee , Lee Sung‐Mi , Kim Hyoun‐Ee , Lee Kyung‐Woo
Published: February 2006

Piezoelectric fibers with internal electrodes were fabricated by the co‐extrusion process. The initial feedrods, which were composed of an outer piezoelectric PZN–PZT layer, a thin conducting PZN–PZT/Ag layer inside, and fugitive carbon black at the center, were co‐extruded through a reduction die (1 mm) to form a continuous fiber. After thermal treatment and sintering, the PZN–PZT/Ag layer became the inner electrode, while the carbon black at the center was removed by oxidation to form an empty space. Three different types of fibers were produced: (i) solid fiber filled with an inner electrode, (ii) hollow fiber clad with a uniform inner electrode, and (iii) hollow fiber clad with a partial inner electrode. The piezoelectric properties of the fibers were evaluated in terms of their longitudinal strain (s31) or transverse displacement. When the dimensions of the fiber were 840 μm (outer diameter) × 420 μm (inner diameter) × 40 mm (length), the longitudinal strains of the solid fiber with the inner electrode and hollow fiber clad with the uniform inner electrode were 5.25 × 10−5 and 8.5 × 10−5 m/m, respectively, under an applied voltage of 100 V (0.48 kV/mm) at a frequency of 100 Hz. For the hollow fiber clad with a partial inner electrode with the same dimensions, the transverse displacement was 80 μm under the same applied electric field.
A Four‐Point Bend Technique to Determine Dynamic Fracture Toughness of Ceramics
Authors: Weerasooriya Tusit , Moy Paul , Casem Daniel , Cheng Ming , Chen Weinong
Published: February 2006

The procedure for determining quasi‐static fracture toughness of ceramics has been standardized. To expand the loading rate into the dynamic region, the dynamic equilibrium over the entire specimen needs to be satisfied to interpret the crack tip loading state with the far‐field loading conditions. Furthermore, to determine the loading‐rate effects, the loading rate at the crack tip should be nearly constant during an experiment. A new four‐point bending experimental technique, based on a split Hopkinson pressure bar, has been developed to determine the dynamic fracture toughness of ceramics at high rates under valid conditions, which is demonstrated through the determination of the dynamic fracture toughness as a function of loading rate for a silicon carbide (SiC–N).
High‐Temperature Oxidation of a Cu–Ni Based Cermet: Kinetic and Microstructural Study
Authors: Rioult Fabien , Pijolat Michèle , Valdivieso Françoise , Prin‐Lamaze Marie‐Agnès
Published: February 2006

The oxidation of a cermet composed of nickel ferrite (NixFe3−xO4), nickel oxide (NiyFe1−yO), and Ni–Cu alloy (CuzNi1−z) (with x=0.8, y=0.84, and z=0.44) has been studied by thermogravimetry, at 960°C, under controlled oxygen partial pressure. The rate of oxidation increases with the oxygen partial pressure up to 5.1 × 103 Pa, then it becomes independent of the oxygen pressure. This is due to the presence of the two copper oxides, CuO and Cu2O, above this oxygen pressure. Scanning electron microscopy observation of oxidized samples has shown that the oxidation mechanism involves both external and internal oxidation.
Synthesis, Microstructural Characterization, and Mechanical Property Evaluation of Vacuum Plasma Sprayed Tantalum Carbide
Authors: Balani Kantesh , Gonzalez Gabriela , Agarwal Arvind , Hickman Robert , O'Dell J. Scott , Seal Sudipta
Published: February 2006

Tantalum carbide (TaC) is an ultra‐high‐temperature ceramic for potential applications as protective coating, furnace components, propulsion liners for space shuttles and aircrafts, etc. Microstructural and mechanical behavior of vacuum plasma‐sprayed (VPS) TaC has been investigated in the present study. Apart from major TaC phase, microstructural definitions elucidated Ta2C, non‐stoichiometric TaCx phases (0.83≤x≤0.94), partial grain formation, polygonization of grains, and inhomogeneous C/Ta ratios in the sprayed structure. Near‐isotropy in the fracture–toughness ratio (Kaxial/Ktrans=1.01) is attributed to compact coating, fine‐closed porosity, and distribution of non‐stoichiometric phases.
Effect of Slip Dispersion on Microstructure Evolution During Isothermal Sintering of Cast Alumina
Authors: McAfee Richard J. , Nettleship Ian
Published: February 2006

The effect of slip dispersion on the consequent densification and microstructure evolution of alumina was studied for isothermal sintering. As expected, cast alumina bodies produced with flocculated slip required longer sintering time to reach high density. Quantitative microstructure analysis was used to study the relationships between the slip dispersion condition, the densification behavior, and microstructure evolution of cast alumina during sintering at 1350°C. A microstructural description based on pore boundary tessellation revealed a correlation between the degree of flocculation, tessellation cell properties, and densification rate. A conceptual understanding of the sintering of agglomerated powders was used to explain the observations.
Yttria Stabilized Zirconia Hollow Fiber Membranes
Authors: Liu Lihong , Tan Xiaoyao , Liu Shaomin
Published: February 2006

Yttria‐stabilized zirconia (YSZ) hollow fiber membranes have been developed by a combined phase inversion and sintering method. An organic binder solution (dope) containing suspended YSZ particles is spun to form a hollow fiber precursor, which is then sintered at elevated temperatures. The prepared hollow fibers have the asymmetric structure including the sponge‐like structures at center, sandwiched by the long finger‐like structures located at the outer and inner walls of the fibers. Experimental results indicate that by controlling the YSZ/polymer weight ratio at 9 or 10 and sintered at a temperature of 1590°C or 1550°C for 10 h, respectively, gas‐tight asymmetric YSZ hollow fiber membranes with high mechanical strength can be obtained.
High‐Frequency Induction Heat Sintering of Mechanically Alloyed Alumina–Yttria‐Stabilized Zirconia Nano‐Bioceramics
Authors: Kim Sug Won , Khalil Khalil Abdel‐Razek
Published: February 2006

Nanostructured alumina—20 vol% 3‐yttria‐stabilized zirconia (3YSZ) powder composites were synthesized by the wet‐milling technique. The starting materials were a mixture of alumina micropowder and 3YSZ nanopowders. The mixtures were optimized for good sintering behaviors, high hardness, and toughness. Nano‐crystalline grains were obtained after milling for 24h. The nano‐structured powders were then processed to full density at different temperatures by high‐frequency induction heat sintering. Effects of sintering temperature on the hardness, toughness, and microstructure properties have been studied. Al2O3–3YSZ composites with higher hardness, toughness, and smaller grain size have successfully been developed at relatively low temperatures by this technique.
Solid‐State Reactivity of the ZnO‐xMn2O3System During Heat Treatment
Authors: Kakazey M. , Vlasova M. , Dominguez‐Patiño M. , Kliava J. , Tomila T.
Published: February 2006

Using X‐ray, infrared, and electron paramagnetic resonance methods, the reactivity of ZnO+xMn2O3systems during heat treatment was studied. Results showed that the solubility of manganese (Mn) in zinc oxide (ZnO) is lower than 3% and that reaction diffusion occurs. Reaction processes that take place in this system promote disintegration of Mn2O3particles into microfragments and causes them to move along the surface of the ZnO particles (solid‐state reactive wetting process).
Physical Processes Involved in Production of the Ancient Pigment, Egyptian Blue
Authors: Pradell Trinitat , Salvado Nativitat , Hatton Gareth D. , Tite Michael S.
Published: February 2006

Egyptian blue, which was the first synthetic pigment to be used in antiquity, consists of crystals of calcium‐copper tetrasilicate (i.e. cuprorivaite (CaCuSi4O10)). The physical processes associated with the formation of Egyptian blue were investigated by high‐temperature X‐ray diffraction measurements on synthetic mixtures of quartz, malachite, and calcium carbonate. The high‐brilliance, high‐energy radiation ID15B beamline at the European Synchrotron Radiation Facility was necessary to ensure good time/temperature resolution, penetration, and high‐quality data. The results established that the Egyptian blue crystals are formed through nucleation and growth within a liquid or glass phase, even for mixtures with an alkali content as low as 0.3 wt% soda. Furthermore, the microstructures observed in a scanning electron microscope indicated the ancient Egyptian blue pigments were produced from mixtures containing several weight percent of alkali.
Evaluation and Statistical Analysis of Dielectric Permittivity of BaTiO3 Powders
Authors: Tsurumi Takaaki , Sekine Takashi , Kakemoto Hirofumi , Hoshina Takuya , Nam Song‐Min , Yasuno Hiroaki , Wada Satoshi
Published: February 2006

A slurry method was used to determine the dielectric permittivity (ɛr) of BaTiO3 powders with different characteristics, such as tetragonality (c/a ratio), density, particle size, and specific surface area. The ɛr of powders highly depended on their characteristics. In order to extract the effect of each characteristic, a statistical analysis was carried out to represent the ɛr of powders with an empirical formula. A fairly good agreement was obtained between observed data and those estimated from the formula. The ɛr decreased with particle size because of the size effect of BaTiO3 and high tetragonality and density was essential to obtain high ɛr of powders.
Combined Effect of Salt Water and High‐Temperature Exposure on the Strength Retention of Nextel™720 Fibers and Nextel™720‐Aluminosilicate Composites
Authors: Parthasarathy Triplicane A. , Cinibulk Michael K. , Zawada Larry P.
Published: February 2006

The relative contribution of fiber strength loss to reported degradation in the mechanical behavior of Nextel™720‐aluminosilicate composites after exposure to salt fog (ASTM B117) was explored. Single filament tension tests were performed on Nextel™720 (3M, Inc., Minneapolis, MN) fibers after immersion in NaCl solutions followed by high‐temperature exposure in air. The results were compared with the behavior of control specimens which received high‐temperature exposure but were not immersed in NaCl solution. There was no degradation in fiber strengths for NaCl solutions below 1 wt%. However, significant degradation was observed at 5 wt% NaCl upon exposure to temperatures between 900° and 1150°C, while no degradation was observed upon an exposure to 1200°C. The relative contribution of fiber strength loss to composite degradation was estimated as nearly 50%, indicating that both fibers and matrix/interface degrade from exposure to salt water. X‐ray diffraction and transmission electron microscopy of the exposed fibers and composites were conducted to help rationalize the observations. Microstructure of degraded fibers showed presence of Na at grain boundaries near the surface, without any evidence of a crystalline phase, indicating weakening from segregation or formation of an amorphous phase. The degraded composites showed that matrix and fiber/matrix interfaces had Na rich regions/phases.
Thermal Behavior of BaTiO3 Particles Synthesized by Plasma Chemical Vapor Deposition
Authors: Nakano Hiromi , Suzuki Keigo , Kizima Kazunori
Published: February 2006

The thermal behavior of nanoparticles BaTiO3, prepared by a radio‐frequency plasma chemical vapor deposition (RF‐plasma CVD) method, was characterized by various analysis methods. The BaCO3 phase was included in the powder as byproducts, which is also observed in hydrothermal BaTiO3 powder. The BaCO3 phase decomposed and disappeared by annealing at 873 K for 30 min. H2O, N2, CO2 and H2, were detected by a thermal desorption spectra measurement from BaTiO3 powder. The annealed powder became well‐crystallized particles without grain growth, although as‐prepared powder included polycrystalline particles. We successfully observed in‐situ grain growth for BaTiO3 nanoparticles by thermal transmission electron microscope. At the initial step of normal grain growth, very fine particles with 40–60 nm diameters started to merge into the larger grains around 1083 K. The migration rate was measured by video images and a grain boundary diffusion coefficient Dgb was calculated.
An assessment of the current structure of food demand in urban China
Authors: Gould Brian W. , Villarreal Hector J.
Published: February 2006

We evaluate the current structure of food demand in urban China by using household expenditure survey data from five provinces. Two complementary analyses are undertaken. First, an aggregate analysis based on a fractional logit model is used to examine how households allocate food expenditures across the food‐at‐home (FAH) and food‐away‐from‐home (FAFH) categories. This is followed by a disaggregated analysis of how households allocated their FAH expenditures across 12 commodity categories. A Quadratic Almost Ideal Demand System (QUAIDS) is used. We find evidence of significant food purchase substitution and complementarity.
Social welfare effects of removing multiple exchange rates: evidence from the rice trade in Iran
Authors: Bakhshoodeh M. , Thomson K. J.
Published: February 2006

In order to encourage the involvement of the private sector in importing rice, the Iranian government plans to relax the system of multiple foreign exchange rates applied to importers wishing to supply the domestic market. In this article, the welfare effects of removing the current controls on the rice trade, and a domestic rice coupon program, are evaluated by applying a partial equilibrium analysis to 1961–1999 data. The results show that, as far as foreign exchange is concerned, liberalization of the rice market causes an increase in rice imports, mainly due to a decrease in domestic supply. In welfare terms, the loss in producer surplus from rice market liberalization is relatively high, but most rice consumers, and the Iranian taxpayer, would gain. Overall, gains to consumers and taxpayers are estimated to be higher than the losses incurred by domestic suppliers, and therefore net social welfare at national level can be improved by rice market liberalization in Iran. Issues for further discussion include residual food security roles for the state, and supply‐side adjustments in terms of resource use and higher‐quality production.
An examination of economic efficiency of Russian crop production in the reform period
Authors: Osborne Stefan , Trueblood Michael A.
Published: February 2006

This article examines economic efficiency (EE) of crop production of Russian corporate farms for 1993–1998. EE declined over the period, due to declines in both technical and allocative efficiency. Technical efficiency (TE) results indicate that output levels could have been maintained while reducing overall input use by an average of 29–31% in 1998, depending on the method used, while the allocative efficiency (AE) results show that costs could have been reduced about 30%. The EE scores show that Russian corporate farms could have increased efficiency by reducing the use of all inputs, particularly fertilizer and fuel. Russian agriculture inherited machinery‐intensive technology from the Soviet era, which may be inappropriate given the relative abundance of labor in the post‐reform environment. Investment constraints have prevented the replacement of old machinery‐intensive technology with smaller scale machines that allow for a more labor‐using technology.
Optimal pest control in greenhouse production of ornamental crops
Authors: Schumacher Sara K. , Marsh Thomas L. , Williams Kimberly A.
Published: February 2006

In this study, we develop a conceptual bioeconomic model of floriculture production with aesthetic benefits, wherein optimal decision rules depend on an intertemporal economic objective to maximize profits subject to economic and biological processes. Necessary conditions of the model identify optimal trajectories (e.g., simultaneous, single, or cycling controls) that define decision rules and economic thresholds for profit maximizing growers producing crops with aesthetic attributes. The necessary conditions also highlight intertemporal trade‐offs between aesthetic benefits and expected future net benefits of arthropod stocks, which have important policy implications. The model is applied to the greenhouse production system of ivy geranium.