bluuebunny/crossref_metadata_2025 huggingface dataset:
Morphology of the buccopharyngeal portion of the gill in the fathead minnow Pimephales promelas (Rafinesque)
Authors: Walker Elizabeth R. , Fidler Stephen F. , Hinton David E.
Published: February 2005

Buccopharyngeal epithelium covering gill arches and gill rakers of the fathead minnow was studied by light microscopic, scanning, and transmission electron microscopic techniques. Mature mucous cells in goblet pattern and nonmucus containing cells were in the apical one‐third of the tissue. The latter cells contributed to a surface microridge system which overlapped apices of goblet cells. The bottom of the epithelium was comprised of a continuous row of darkly stained basal epithelial cells. In this region, two to three epithelial cells of similar staining characteristics were piled up forming apical columns which partially encircled nests of lightly stained cells. A basal lamina and thick basement lamella of about 20 plies of orthogonally arranged collagen supported the epithelium. Numerous taste buds were seen in gill arches and rakers. Taste bud cellular components included marginal cells, light receptor cells, dark receptor cells, and basal cells. These were identical in all taste buds. Taste bud surface morphology differed between gill arch and raker. Pores of the former were depressed, while those of the latter were raised. Thick microvilli of taste pores were apical extensions of light cells, while smaller, more numerous microvilli were projections from dark cells.
The origins of the afferent fibers to the lingual muscles of the dog, a retrograde labeling study with horseradish peroxidase
Authors: Chibuzo Gregory A. , Cummings John F.
Published: February 2005

The origin of the afferent fibers to the lingual muscles of the dog was investigated by means of retrograde transport of horseradish peroxidase (HRP) from injection sites in the tongue and the extrinsic lingual muscles. Intralingual injections were not satisfactory because the enzyme diffused beyond the intrinsic lingual muscles to include virtually all tissues within the tongue. Thus, the resultant retrograde labeling of cell bodies of the trigeminal, geniculate, glossopharyngeal, vagal, and first cervical (C1) spinal ganglia represented a composite of lingual sensory innervation.

In order to confine HRP uptake to intramuscular nerve endings, injections were limited to surgically isolated extrinsic lingual muscles, i.e., the genioglossus, hyoglossus, and styloglossus. After these intramuscular injections, labeled neurons appeared ipsilaterally in the C1 spinal ganglion, the proximal vagal (jugular) ganglion, and trigeminal ganglion. Earlier suggestions that the lingual proprioceptive neurons of the dog reside in the distal vagal (nodose) ganglion and hypoglossal ganglia were not confirmed. The mesencephalic nucleus of the trigeminal nerve failed to label after enzyme injections into the tongue or the extrinsic lingual muscles.

The retrograde labeling of cell bodies in the C1 spinal ganglion was abolished when HRP injections into the extrinsic lingual muscles were preceded by surgical interruption of the ansa cervicalis or distal section of the hypoglossal nerve. Retrograde labeling of neurons in the proximal vagal ganglion persisted after hypoglossal nerve transections.
Quantification of microvasculature in the canine spinal cord
Authors: Ireland William P. , Fletcher Thomas F. , Bingham Christopher
Published: February 2005

Capillary density and capillary orientation in canine spinal cords were estimated by calculating actual lengths, surfaces, and volumes of capillary segments in tissue sections. Transverse, sagittal, and frontal section planes were sampled from dorsal, ventral, and lateral funiculi and from dorsal and ventral gray horns of spinal segments C3, T6, and L3 from three dogs. Capillaries were defined as vessels less than 10 μm in diameter. Electron microscopy of 104 such vessels revealed no muscle coat but collagen fibrils between endothelium and astrocyte process in 68% of the white matter capillaries and 16% of those in gray matter. Capillary diameter was significantly different among regions in some cases, but consistent patterns of variation were not found. Capillary density was four to five times greater in gray matter than in white matter. Capillary density differed significantly among the same‐size dogs, but within dogs, density was similar among segments and within gray matter and white matter regions. In 62% of the transverse sections, capillary orientation was significant but mean direction was variable. Significant capillary orientation was found in 89% of the sagittal and frontal sections, and the mean direction was always along the craniocaudal axis of the spinal cord. The craniocaudal orientation was significant in 96% of the white matter sections and 78% of the gray sections, and in 97% of the cervical and thoracic sections but only 73% of the lumbar sagittal and frontal sections.

Because capillary orientation is neither isotropic nor regular, unbiased, lowvariance estimates of capillary density cannot be expected without resorting to excessive sampling. An efficient method of quantifying spinal capillaries for comparative purposes by counting number of profiles per unit area is recommended.
Effects of cold and melatonin on the microtubules of the toad sciatic nerve
Authors: Piezzi Ramón S. , Cavicchia Juan C.
Published: February 2005

The effects of melatonin and cooling on the disintegration and reassembly of microtubules were studied in the sciatic nerve of the toad. Control and melatonin‐treated nerves showed disintegration of the majority of microtubules after 2 hours of cooling. When room temperature was restored, microtubules were reformed in the controls, but not in the nerves treated by melatonin where the disorganization persisted. These results demonstrate that melatonin interferes with the microtubular reassembly after cooling of the axons of the sciatic nerve.
A technique for improved fixation of the pigeon central nervous system for electron microscopy
Authors: Rieke Garl K. , Bowers Daniel E. , Silvy Nova J.
Published: February 2005

The central nervous system (CNS) of the pigeon has been difficult to fix with consistency, and consequently this problem has impeded ultrastructural studies of various parts of the pigeon brain. Here we describe a method for effective fixation of the pigeon CNS and discuss the three principal problems associated with good fixation of this animal's brain. The animal was deeply anesthetized and the thoracic cavity was opened without collapsing the pectoral girdle upon the brachiocephalic trunks and the common carotids. The perfusion pressure was raised to 140–150 mm Hg to overcome the high resistance of the small diameter, long common carotids. Heparin was added to the wash buffer to retard coagulation of blood in the vascular bed of the brain. The method is not foolproof, but with care excellent fixation can be achieved.
Necrotic death but not irradiation abolishes costimulation of T‐cell effector functions and survival by CD80‐expressing tumor cells
Authors: Stärck Lilian , Scholz Christian , Blankenstein Thomas , Dörken Bernd , Daniel Peter T.
Published: March 2005

Tumor vaccination by the use of gene‐modified cancer cells that provide costimulatory signals has been successfully applied in preclinical animal models and is currently evaluated in a variety of clinical settings. In previous work, we demonstrated the efficacy of B7.1/CD80 to promote tumor immunity in syngeneic murine models and to prevent deletion of activated T cells by activation‐induced cell death (AICD). In clinical trials, tumor cell vaccines are generally inactivated to avoid transfer of live tumor cells, i.e., additional tumor burden. Previous data indicated, however, that inactivation of tumor cells by lethal ionizing irradiation abrogates tumor vaccination by CD80‐expressing cells. Here, we compare living and irradiated allogeneic tumor cells regarding their capacity to induce T‐cell effector functions and their propensity to interfere with T‐cell deletion by apoptosis. Both lethally irradiated and nonirradiated tumor cells facilitated T‐cell proliferation, tumor cell lysis, and interfered with T‐cell AICD to a similar extent. In contrast, necrotic tumor cells failed to costimulate T‐cell effector functions. Thus, irradiation does not seem to hamper tumor cell‐mediated costimulation of T‐cell effector functions. In contrast, necrosis of gene‐modified tumor cells abrogates costimulation of T cells by CD80‐expressing cells. © 2005 Wiley‐Liss, Inc.
Constructions of sparse asymmetric connectors with number theoretic methods
Authors: Baltz Andreas , Jäger Gerold , Srivastav Anand
Published: March 2005

We consider the problem of connecting a set 1 of n inputs to a set O of N outputs (n ≤ N) by as few edges as possible such that for every injective mapping f : I → O there are n vertex disjoint paths from i to f(i) of length k for a given k ∈ IN. For k = Ω(logN + log2n) Oruç (J Parallet Distributed Comput 1994, 359–36610) gave the presently best (n,N)‐connector with O(N + n · logn) edges. For k = 2 and N the square of a prime, Richards and Hwang (1985) described a construction using
$N\lceil\sqrt{n + 5/4} - 1/2\rceil + n\lceil\sqrt{n + 5/4} - 1/2 \rceil \sqrt{N}$
edges. We show by a probabilistic argument that an optimal (n,N)‐connector has Θ(N) edges, if n ≤ N½−ε for some ∈ ≥ 0. Moreover, we give explicit constructions based on a new number theoretic approach that need at most $N\lceil \sqrt{3n/4}\rceil + 2n\lceil \sqrt {3n/4}\rceil\lceil\sqrt{N}\rceil$
edges for arbitrary choices of n and N. The improvement we achieve is based on applying a generalization of the Erdős‐Heilbronn conjecture on the size of restricted sums. © 2005 Wiley Periodicals, Inc. NETWORKS, Vol. 45(3), 119–124 2005
Adolescents with a childhood experience of parental divorce: a longitudinal study of mental health and adjustment
Authors: St⊘rksen Ingunn , R⊘ysamb Espen , Moum Torbj⊘rn , Tambs Kristian
Published: February 2005

**This is a prospective Norwegian study of a group of adolescents with an experience of parental divorce or separation and a comparison group without this experience . Mean age at T1 was 14.4 years and mean age at T2 was 18.4 years. Parental divorce was prospectively associated with a relative change in anxiety and depression, subjective well‐being, self‐esteem, and school problems. Considering boys separately, parental divorce was prospectively associated only with school problems. Among the girls, divorce was prospectively associated with all variables. The effect of divorce on relative change was partially mediated by paternal absence.
The space \( BV\left(\right.S^{2},S^{1}\left.\right) \): minimal connection and optimal lifting
Authors: Ignat Radu
Published: February 2005

We show that topological singularities of maps in

\mathrm{BV}(S^{2},S^{1})

can be detected by its distributional Jacobian. As an application, we construct an optimal lifting and we compute its total variation.

On montre que le jacobien d'une fonction

u \in \mathrm{BV}(S^{2},S^{1})

permet de localiser les singularités topologiques de

u

. On applique ce résultat à la construction d'un relèvement optimal et on calcule sa variation totale.
Postoperative analgesia in children — current practice in Germany
Authors: Stamer Ulrike M. , Mpasios Nektarios , Maier Christoph , Stuber Frank
Published: February 2005

German departments of anaesthesia were surveyed to determine current practice of postoperative pain management in children. The response rate of the survey was 58.6%: Questionnaires of 383 departments in which paediatric surgery was performed could be analyzed. 37.3% operated an acute pain service (APS). In 58.8% of the hospitals, postoperative pain management in children was mainly performed by surgeons or pediatricians. Anaesthesiologists or an APS were in charge for pain management in children in 38.6% of the institutions. Non‐opioid analgesics were the drugs most widely used (93.4%), whereas i.v. opioids were never used in 20.9% of the hospitals and used less than once a week in 28.7%. The intramuscular route was chosen at least occasionally by 27.7% of the respondents. Peripheral and central regional techniques were performed in most of the departments, however, frequency of use varied considerably between hospitals running or not running an APS. The majority performed the techniques of regional anaesthesia less than once a week. The basic primary quality criterion of pain therapy, a regular measurement and documentation of pain scores, was performed in only 4% of the institutions.

Paediatric pain management does not meet quality criteria and standards of care already established in adults. In the future, additional education of the medical staff considering analgesic techniques and measurement of pain scores has to be emphasized.
Rapid-response indicators of changes in resource state based on Mediterranean bottom-trawl surveys
Authors: Ragonese Sergio , Morizzo Gaia , De Santi Alberto , Bianchini Marco L.
Published: February 2005

The authors propose a method for developing operational indicators of resource state, with an example based on a set of eight variables (mean abundance index in weight, mean body weight, median length, sex ratio, sex ratio by selected length class, mean and median female length-at-maturity, and percentage of females at maturity) derived from surveys conducted in the Strait of Sicily (central Mediterranean Sea, 1994–2002) for six target species. The method combines univariate (kite diagrams, sphere displacement plots) and multivariate techniques (multi-dimensional scaling).
Comparing the Benguela and Humboldt marine upwelling ecosystems with indicators derived from inter-calibrated models
Authors: Moloney Coleen L. , Jarre Astrid , Arancibia Hugo , Bozec Yves-Marie , Neira Sergio , Roux Jean-Paul , Shannon Lynne J.
Published: February 2005

Large-scale, mass-balance trophic models have been developed for northern and southern regions of both the Benguela and Humboldt upwelling ecosystems. Four of these Ecopath models were compared and calibrated against one another. A common model structure was established, and a common basis was used to derive poorly known parameter values. The four resulting models represent ecosystems in which the main commercial fish species have been moderately to heavily fished: central-southern Chile (1992), northern-central Peru (1973–1981), South Africa (1980–1989), and Namibia (1995–2000). Quantitative ecosystem indicators derived from these models were compared. Indicators based on large flows (involving low trophic levels) or top predators were not well estimated, because of aggregation problems. Many of the indicators could be contrasted on the basis of differences between the Benguela and Humboldt systems, rather than on the basis of fishing impact. These include integrated values relating to total catches, and trophic levels of key species groups. Indicators based on integrated biomass, total production, and total consumption tended to capture differences between the model for Namibia (where fish populations were severely reduced) and the other models. We conclude that a suite of indicators is required to represent ecosystem state, and that interpretation requires relatively detailed understanding of the different ecosystems.
Lamellar body count as a predictor of neonatal lung maturity in high‐risk pregnancies
Authors: Abd El Aal D.E.M. , Elkhirshy A.A. , Atwa S. , El‐Kabsh Mohamed Y.
Published: February 2005

Objectives

To compare the usefulness of a lamellar body count, a fluorescence polarization assay, and the foam stability index for predicting neonatal lung maturity in high‐risk pregnancies.

Setting

This study was conducted at the Department of Obstetrics and Gynecology and the Department of Pediatrics, Assiut University Hospital.

Design

A prospective clinical trail.

Subjects and Methods

This study was performed after recruiting 73 pregnant women, 52 with high‐risk pregnancies (25 had diabetes and 27 had premature labor) and 21 with a healthy full‐term singleton pregnancy as controls. All women were delivered in the Department of Obstetrics and Gynecology of Assiut University Hospital. The newborns with respiratory distress syndrome (RDS) were admitted in the neonatal intensive care unit of the Department of Pediatrics. Amniotic fluid specimens were obtained near delivery. Apgar score, vital signs, anthropometric data, and complete clinical examination results were available for all newborns, and particular emphasis was placed on signs of RDS.

Results

The incidence of RDS was 44.2% in the newborns of women who had experienced a high‐risk pregnancy (of these, 82.6% were born preterm and 17.4% to diabetic mothers). We found that a lamellar body count is a good screening test for predicting neonatal lung maturity. It is as good as the fetal lung maturity assay by fluorescence polarization in some respects and better in others; moreover, it is better than the foam stability index test in all respects. A lamellar body count with cutoffs of 41×103/μL and 18×103/μL was a good predictor of low and high risks of RDS in newborns. Values between 19×103/μL and 40×103/μL were the best to predict an intermediate risk of RDS.

Conclusion

Lamellar body count is a good screening test for predicting the degree of neonatal lung maturity.
Diagnosis of human cytomegalovirus intrauterine infection using fetal cells from maternal blood
Authors: Chen H.P. , Wang T.R. , Xiang W.P. , Xu X.Y. , Zhang M. , Xu J.P.
Published: February 2005

Objective

The sensitivity and specificity for the noninvasive prenatal diagnosis of human cytomegalovirus intrauterine infection were estimated by using isolating single fetal cells from maternal peripheral blood.

Methods

Micromanipulation techniques were employed to isolate single fetal nucleated erythroblasts from 273 maternal blood samples. SRY gene and HCMV‐DNA in single fetal cells were detected by multiple primed in situ labeling (PRINS) from 76 HCMV‐DNA positive samples of maternal peripheral blood. 273 samples of maternal peripheral blood were tested for SRY gene and HCMV‐DNA in single fetal cells by primed extension preamplification (PEP) and polymerase chain reaction (PCR).

Results

The detection rate of fetal cells from maternal blood was 100% with micromanipulation techniques. The sensitivity of PRINS for SRY gene detection was 97.56% and its specificity was 100%. The sensitivity and specificity of PEP and PCR for SRY gene detection were 97.39% and 99.17%, respectively. The sensitivity of PRINS for HCMV‐DNA detection was 92.68% and the specificity was 100%. The sensitivity and specificity of PEP and PCR for HCMV‐DNA detection were 95.12%and 100%, respectively.

Conclusion

The technique for noninvasive prenatal detection of intrauterine infection of HCMV using single fetal cells from maternal peripheral blood by using PRINS and PEP and PCR is more reliable than the CMV‐DNA detection in peripheral maternal blood, amniocentesis or percutaneous umbilical blood sampling.
Effective Moisture Diffusivity in Porous Materials as a Function of Temperature and Moisture Content
Authors: Tong C. H. , Lund D. B.
Published: March 2005

Regular regime theory was used to evaluate the effective moisture diffusivity of a commercial white bread, plain sheet muffin, and baking powder biscuit as a function of moisture content based on desorption experiments. Volume shrinkage during drying was also monitored. The existence of regular regime periods in desorption processes for porous baked products was experimentally verified. Effective moisture diffusivity at temperatures between 20 and 100°C ranged from 2.5×10−5to 5.5×10−3cm2/s in the moisture range of 0.1–0.7 g of H20/g of solid for bread, 9.35×10−6to 9.7×10−4cm2/s in the moisture range of 0.1–0.65 g of H20/g of solid for biscuit, and 8.4×10−6to 1.54×10−3cm2/s in the moisture range of 0.1–0.9 g of H20/g of solid for muffin. The effect of temperature on effective moisture diffusivity was adequately modeled by the Arrhenius relationship. Activation energies for bread, biscuit, and muffin were found to be independent of moisture content and were 51, 51, and 55 kJ/mol, respectively. Mathematical models to relate the effective moisture diffusivity to temperature and moisture content were developed.
Degradation of Pesticides in a Continuous‐Flow Two‐Phase Microemulsion Reactor
Authors: Komives C. , Osborne D. , Russell A. J.
Published: March 2005

Biocatalytic processes in reversed micelles are limited by the need for continuous reactors in which reaction and separation are feasible. In this paper, we report the design and testing of a continuous‐flow centrifugal bioreactor for the enzyme‐catalyzed hydrolysis of the common pesticide paraoxon in reverse micelles of Tween 85. In this system, organophosphorus hydrolase catalyzes hydrolysis of the pesticide in an organic‐organic two‐phase system. The enzyme is retained in one of the phases by encapsulation in reversed micelles, while the other phase is under a continuous flow. This liquid‐liquid plug‐flow reactor does not leach enzyme because the enzyme is not soluble in the flowing organic phase that contains the paraoxon.
Temperature and Growth Rate Effects on the hok/sok Killer Locus for Enhanced Plasmid Stability
Authors: Wu Kuowei , Jahng Deokjin , Wood Thomas K.
Published: March 2005

The hok/sok locus, isolated from the multiple‐resistance plasmid R1 of Escherichia coli, is very efficient at ensuring the stable maintenance of plasmids in Gram‐negative systems by killing plasmid‐free cells as they arise. To investigate independently the influence of temperature and growth rate on the effectiveness of hok/sok, continuous fermentations have been conducted with the pUC‐based, IPTG‐induced, β‐galactosidase expression vector pTKW106. At fixed temperature (37°C), decreasing the dilution rate decreased plasmid stability, and at a fixed, low dilution rate (D = 0.15/h), decreasing the temperature resulted in an increase in plasmid stability. These trends are explained by the specific β‐galactosidase activity of each continuous fermentation: higher, specific, recombinant protein expression led to decreased plasmid stability (due to either segregational or structural instability, as determined by plasmid DNA isolation). A representative fed‐batch medium produced more β‐galactosidase on a volumetric basis than M9C in the chemostat, and addition of the hok/sok locus increased segregational stability by 8–22‐fold in continuous fermentations that lacked antibiotic selection pressure and in which β‐galactosidase was constantly expressed at 12% of total cell protein for 60 h (43–47 generations).
Another biological effect of tosylphenylalanylchloromethane (TPCK): it prevents p47phoxphosphorylation and translocation upon neutrophil stimulation
Authors: GILLIBERT Maggaly , DEHRY Zakia , TERRIER Micheline , EL BENNA Jamel , LEDERER Florence
Published: March 2005

TPCK (tosylphenylalanylchloromethane), first discovered as a serine protease inhibitor, has been described to affect in diverse systems a number of physiological events probably unrelated to its antiprotease effect, such as proliferation, apoptosis and tumour formation. In the present study, we focus on its inhibition of the neutrophil respiratory burst, an important element of non-specific immunological defence. The superoxide anion-producing enzyme, NADPH oxidase, is quiescent in resting cells. Upon cell stimulation, the redox component, membrane-bound flavocytochrome b558, is activated when the cytosolic factors (p47phox, p67phox and p40phox, as well as the small GTPase Rac) associate with it after translocating to the membrane. This requires the phosphorylation of several p47phox serine residues. The signal transduction events leading to enzyme activation are not completely understood. In the past, the use of diverse protease inhibitors suggested that proteases were involved in NADPH oxidase activation. We suggested previously that TPCK could prevent enzyme activation by the phorbol ester PMA, not due to inhibition of a protease, but possibly to inhibition of the cytosolic factor translocation [Chollet-Przednowed and Lederer (1993) Eur. J. Biochem. 218, 83–93]. In the present work, we show that TPCK, when added to cells before PMA, prevents p47phox phosphorylation and hence its translocation; moreover, when PMA-stimulated cells are incubated with TPCK, p47phox is dephosphorylated and dissociates from the membrane. These results are in line with previous suggestions that the respiratory burst is the result of a series of continuous phosphorylation and dephosphorylation events. They suggest that TPCK leads indirectly to activation of a phosphatase or inactivation of a kinase, and provide the first clue towards understanding the steps leading to its inhibition of NADPH oxidase activation.
Photosynthetic activity of Lolium perenne as a function of endophyte status and zinc nutrition
Authors: Monnet Fabien , Vaillant Nathalie , Hitmi Adnane , Sallanon Huguette
Published: February 2005

Grass infection by endophyte fungi can confer host resistance to different types of stress, but limited evidence is available on the related effects on the photosynthetic mechanism of the grasses. Zinc has direct and indirect effects on this mechanism and is one of the more important environmental pollutants. To measure whether photosynthesis of the host plant is affected by fungal infection when endophyte-free and endophyte-infected grasses contain similar excess zinc concentrations in their leaves, two batches of Lolium perenne L. cv. Apollo plants were established, one batch was infected with Neotyphodium lolii, the other was not. Both batches were then treated for 8 d with a nutrient solution containing 0, 1, 5, 10 or 20 mm ZnSO4. The increase in zinc concentration induced some reduction in photosystem II (PSII) activity but not enough to account for the total drop in the net photosynthetic rate. Endophyte fungus favoured maintenance of the PSII activity, but did not significantly modify the net photosynthesis and similar zinc concentration levels were observed in leaves of both types of plant. Interactive effects of zinc and light induced less photodamage to the PSII of the host, which is able to react to an increase in photon flux density (PFD). In endophyte-free plants, the reaction centre contributed more than antenna complexes to energy dissipation. In endophyte-infected plants, the quenching of the reaction centre and antenna complexes rose simultaneously and at a constant rate, as zinc concentrations increased.
Mechanoreceptors rather than sedimentable amyloplasts perceive the gravity signal in hypergravity-induced inhibition of root growth in azuki bean
Authors: Soga Kouichi , Wakabayashi Kazuyuki , Kamisaka Seiichiro , Hoson Takayuki
Published: February 2005

Elongation of primary roots of azuki bean (Vigna angularis Ohwi et Ohashi) was suppressed under hypergravity conditions produced by centrifugation, such that the growth rate decreased in proportion to the logarithm of the magnitude of the gravity. The removal of the root cap did not influence the hypergravity-induced inhibition of root growth, although it completely inhibited the gravitropic root curvature. Lanthanum and gadolinium, blockers of mechanoreceptors, nullified the growth-inhibitory effect of hypergravity. These results suggest that the gravity signal for the hypergravity-induced inhibition of root growth is perceived independently from that of gravitropism, which involves amyloplasts as statoliths. Horizontal and basipetal hypergravity suppressed root growth as did acropetal hypergravity, all of which were nullified by the presence of lanthanum or gadolinium. These findings suggest that mechanoreceptors on the plasma membrane perceive the gravity signal independently of the direction of the stimuli and roots may utilise it to regulate their growth rate.
Phase Relations between the Polytitanates of Barium and the Barium Borates, Vanadates, and Molybdates
Authors: MILLET J. M. , ROTH R. S. , PARKER H. S.
Published: March 2005

Phase equilibria in ternary systems involving BaO, TiO2, and the low melting oxides B2O3, V2O5, and Mo03 are reported. The low‐temperature phases BaTi2O5 and BaTi5O11 were not obtained in equilibrium in any of the studied systems. It has been found that the compound reported with the composition Ba3Ti3V4O19 has in fact the composition Ba3TiV4O15. It decomposes at 995 ± 5°C (Ba3TiV4O15→liq+ Ba2V2O7). A new ternary compound Ba2Ti2B2O9 which decomposes into BaTiO3 and a liquid at ∼950°C was also found. Alternative ways to synthesize BaTi4O9 and Ba2Ti9O20 have been found. These compounds can be obtained by heating at relatively low temperature appropriate compositions in the system BaO‐TiO2‐V2O5 or BaO‐TiO2‐MoO3 and dissolving the excess phases in dilute HCI. Ba2Ti9O2o can also be prepared at low temperature in the BaO‐TiO2‐B2O3 system, in which it may show a limited solid solution, offering the possibility of obtaining dense ceramics at low temperature.
Small‐Angle Neutron Scattering from Porosity in Sintered Alumina
Authors: Hardman‐Rhyne K. A. , Berk N. F.
Published: March 2005

A new approach for studying porosity in ceramic or metallic materials has been developed using multiple neutron scattering in the small‐angle regime. This technique enables the measurement of voids from 0.08 to 10 μm in size with 1% to 50% porosity. Whereas a fully dense alumina sample showed no evidence of multiple neutron‐scattering effects, a more porous alumina exhibited striking neutron wavelength dependence. The voids in the latter material are 1.48 μm in mean diameter and 10.5% in volume fraction.
Reaction and Coloration of Glasses with Hydrogen
Authors: Kumar Binod , Russ Karl J.
Published: March 2005

The reaction of NBS 710 glass with hydrogen at 500°C and the resulting coloration of the glass have been studied using optical spectroscopy. Initially the reaction leads to the reduction of iron from ferrous to ferric state which subsequently combines with sulfur resulting in the formation of FeS. The origin of the color centers is proposed to be related to the formation of FeS.
Microstructure of 96% Alumina Ceramics: I, Characterization of the As‐Sintered Materials
Authors: Powell‐Doǧan Cynthia A. , Heuer Arthur H.
Published: March 2005

Characterization of the microstructure and microchemistry of a group of commercial 96% Al2O3 ceramics, using analytical and conventional electron microscopy techniques, was conducted. A continuous glassy grain‐boundary phase was found in all samples, in addition to a number of intragranular and intergranular crystalline second phases; the phases present depended on the original boundary‐glass composition. The faceted nature of many of the Al2O3‐glass interfaces was studied and is thought to be an equilibrium structure.
Liquid Formation at the Peritectic Temperature in Superconducting YBa2Cu3O7−x—Observation of a New Phase YBa4CuAIO8
Authors: Zhou Ji‐Ping , Sorrell Charles C. , Bourdillon Antony J. , Dou Shi‐Xue
Published: March 2005

In the system Y‐Ba‐Cu‐O, partial melting of peritectically decomposing YBa2Cu3O7‐x (123) was used to produce a bulk material of high critical current density when the material was aligned. The liquid formation mechanism and its relation to reaction with alumina refractory was studied. A previously unreported phase of the approximate stoichiometric ratio Y:Ba:Cu:Al = 1:4:1:1 (YBa4CuAlO8) was detected. The crystal structure was determined to be tetragonal, with lattice parameters a0=b0= 1.651 nm, c0= 1.793 nm. The 1411 phase bears a close structural relationship to BaCuO2.
Consolidation Behavior of High‐Performance Ceramic Suspensions
Authors: Novich Bruce E. , Pvatt Dale H.
Published: March 2005

Colloidal processing has been shown to produce low defect and uniform ceramic microstructures from submicrometer ceramic powders. These concepts were applied to colloidal pressing to determine critical design relationships for uniaxial consolidation of dense and uniform green bodies from colloidal suspensions. Carefully controlled constant rate of strain consolidation experiments were carried out using alumina in water. The compression index decreased from 0.143 for a poorly dispersed alumina system to 0.077 for a well‐dispersed alumina suspension compression curve, indicating that the well‐dispersed system is stiffer in consolidation. The compression curves showed that, as the degree of dispersion decreases, increased consolidation stresses are required to achieve a given particle packing density. The compression index increased with increasing strain rate for well‐dispersed alumina suspensions. Permeability through the sample ranged from 3 × 10–8 to 4 × 10−7 cm/s, decreasing with decreasing void ratio during consolidation. Well‐dispersed samples gave lower permeabilities than did poorly dispersed samples over a given consolidation increment. Coefficients of consolidation were nonconstant over the experimental effective stress range, invalidating the general solution to the linear consolidation equation. An approximate incremental solution was applied which indicated rapid pressing cycles are possible by starting with a suspension having a high solids concentration. Application of this consolidation data to nonlinear consolidation models is recommended for more exact prediction of consolidation time.
SEM Quantification of Transgranular vs Intergranular Fracture
Authors: Yang Wein‐Joe , Yu Chang‐Te , Kobayashi Albert S.
Published: March 2005

A SEM procedure for quantifying the percentage area of transgranular fracture and surface roughness was developed to study the fracture morphologies of stable and rapid crack growths in ceramics and ceramic matrix composites. The procedure utilizes software which interprets the SEM line scanning profiles. Results obtained through this procedure were correlated with the visual observation and profilometer measurements of Al2O3 and SiCw/Al2O3 fracture specimens.
Statistics of Flaw Interaction in Brittle Materials
Authors: Lam Khin‐Yong , Cotterell Brian , Phua Swee‐Pheng
Published: March 2005

The problem of elastic interaction of an array of microcracks is considered. The solution is based on an efficient surface integral method using distribution of edge dislocations to represent the microcracks in the mathematical model. From the analysis of the interaction between two identical cracks, it is seen that interaction is most likely to produce a slight enhancement in the stress intensity factor. By performing computer experiments on a random array of microcracks, the effect of crack interaction is studied statistically as a function of the density of the microcracks. The significance of the interaction effects for fracture in ceramics is discussed.
Crystallization of Li2O · Al2O3· 6SiO2 Glasses Containing Niobium Pentoxide as Nucleating Dopant
Authors: Hsu Jen‐Yan , Speyer Robert F.
Published: March 2005

Niobium pentoxide (T form, orthorhombic system) was utilized to promote devitrification in Li2O · Al2O3· 6SiO2 glasses. Two or more mole percentage of this nucleating dopant enhanced crystallization in these glasses. Glasses containing 4.0 and 8.0 mol% T‐Nb2O5 exhibited a high tendency to form dispersed TT‐Nb2O5 (monoclinic system) precipitates during the glass quenching process. The crystallization process in glasses containing 2.0 or 4.0 mol% T‐Nb2O5 occurred as microphase separation, followed by the formation of dispersed TT‐Nb2O5 crystalline precipitates (760°C), followed by β‐quartz solid‐solution (ss) formation (850° to 900°C) heterogeneously nucleated from the precipitates. β‐quartz(ss) transformed to β‐spodumene(ss), along with a polymorphic transition from the TT‐Nb2O5 to M‐Nb2O5 (tetragonal system) crystalline phase.
Analysis of a Microcrack Prototype and Its Implications for Microcrack Toughening
Authors: Cai Hongda , Moran B. , Faber K. T.
Published: March 2005

The stress intensity factor, the volume, and the macroscopic dilatational strain associated with microcracking for various crack lengths and elastic mismatches are examined for a microcrack prototype, which consists of a penny‐shaped crack in the center of spherical particle under residual hydrostatic tension. The results of these quantities and the implications for microcrack toughening are presented. The effects of elastic mismatch between the particle and matrix phases are emphasized.
Effect of Microwave Power on Hydrogen Content in Chemically Vapor Deposited Diamond Films
Authors: Hirai Hisako , Fukunaga Osamu , Odawara Osamu
Published: March 2005

The effect of microwave power on the hydrogen and amorphous carbon contents of diamond films is investigated by the plasma chemical vapor deposition method. The input microwave power during diamond synthesis is varied between 330 and 500 W by using different holder materials, while a constant substrate temperature of 850°C is maintained. The hydrogen content in the synthesized diamond is measured by secondary ion mass spectrometry, and the relative amount of amorphous carbon is estimated from the Raman spectra. The hydrogen count normalized against that of carbon decreases logarithmically with increasing input power; the amorphous carbon amount also decreases with higher input power. The present experimental results prove that hydrogen content can be controlled by varying input microwave power during diamond deposition.
Extreme‐Value Statistics Analysis of Fracture Strengths of a Sintered Silicon Nitride Failing from Pores
Authors: Chao Luen‐Yuan , Shetty Dinesh K.
Published: March 2005

Statistical analysis and correlation between pore‐size distribution and fracture strength distribution using the theory of extreme‐value statistics is presented for a sintered silicon nitride. The pore‐size distribution on a polished surface of this material was characterized, using an automatic optical image analyzer. The distribution measured on the two‐dimensional plane surface was transformed to a population (volume) distribution, using the Schwartz–Saltykov diameter method. The population pore‐size distribution and the distribution of the pore size at the fracture origin were correlated by extreme‐value statistics. Fracture strength distribution was then predicted from the extreme‐value pore‐size distribution, using a linear elastic fracture mechanics model of annular crack around pore and the fracture toughness of the ceramic. The predicted strength distribution was in good agreement with strength measurements in bending. In particular, the extreme‐value statistics analysis explained the nonlinear trend in the linearized Weibull plot of measured strengths without postulating a lower‐bound strength.
Crystal Growth Inhibitor in Binary Borosilicate Glass Composite—Gallium Oxide
Authors: Jean Jau‐Ho , Gupta Tapan K.
Published: March 2005

The effect of gallium oxide on cristobalite formation in binary borosilicate glass composite, containing a low‐softening borosilicate glass (BSG) and a high‐softening high‐silica glass (HSG), has been studied. X‐ray diffraction results show that with a small amount of gallium oxide, 2.5–10 vol%, the precipitation of cristobalite at elevated temperatures is prevented. This result is further evidenced by linear thermal expansion measurement, in which, in contrast to the gallium oxide‐free sample, the thermal expansion coefficients (TCE) of the composite with gallium oxide remain unchanged with sintering time at temperatures investigated and, moreover, are very close to the theoretically calculated values.
Flat R‐Curve from Stable Propagation of Indentation Cracks in Coarse‐Grained Alumina
Authors: Bleise Detlef , Steinbrech Rolf W.
Published: March 2005

The fracture toughness of coarse‐grained A12O3, known for pronounced “Iong”‐crack R‐curve behavior, was studied in the “short”‐crack regime utilizing the stable propagation of indentation cracks in bending. A combination of in situ microscopic crack growth observations and mechanical testing enabled measurement of crack extension curves. They reflect the contributions of residual indentation stress intensity and applied bending stress intensity on the total crack driving stress intensity and allow determination of the residual stress factor χ and the toughness KR. The results indicate that χ depends on indentation load and AR is surprisingly constant rather than increasing. To resolve the latter contradiction with long‐crack R‐curve behavior, combined short/long‐crack fracture tests were performed with the same specimens. Starting with stable indentation crack growth and continuing with stable long‐crack extension, the previous toughness results were confirmed, i.e., constant toughness from indentation cracks and increasing toughness from long cracks. The influence of crack‐opening behavior on bridging‐controlled R‐curve toughening can qualitatively explain the observed discrepancies.
First‐Principles Calculations for Niobium Atoms on a Sapphire Surface
Authors: Kruse Carsten , Finnis Michael W. , Milman Victor Y. , Payne Michael C. , De Vita Alessandro , Gillan Michael J
Published: March 2005

We report first‐principles, self‐consistent calculations of the equilibrium structure, election density, and total energy of a niobium monolayer on a sapphire (0001) surface. The calculations, which are based on the density functional theory in the local density approximation, use norm‐conserving pseudopotentials and a basis of plane waves. We work with a slab which is three Al–O–Al layers in thickness and we assume that the surface Al atoms are replaced by Nb. All the atomic positions are relaxed to minimize the total energy. In contrast to the clean surface, on which the Al atoms relax inwards almost to the level of the surface oxygen, the Nb atoms relax only slightly inwards from the sites where the next Al atoms would sit if the bulk structure were extended. The Nb atoms are partially ionized and there is strong directional bonding, due to the hybridization of d‐orbitals on Nb with the oxygen p‐orbitals. The work of adhesion is 13 eV per Nb atom.
Rapid Formation of Zinc Oxide Films by an Atmospheric‐Pressure Chemical Vapor Deposition Method
Authors: Kamata Kiichiro , Nishino Junichi , Ohshio Shigeo , Maruyama Kazunori , Ohtuki Motohiko
Published: March 2005

Zinc oxide films were prepared by an atmospheric‐pressure chemical vapor deposition method using (acetylacetonato)‐zinc as a source material. Transparent and uniform ZnO films of considerable area (20 × 70 mm, ∼0.3 μm thick) could be obtained easily on a crown glass (CGW #200) with a high deposition rate. The deposition rate first remained constant with increasing substrate temperature (Ts), then increased abruptly from 120 nm/min at Ts= 550°C to 220 nm/min at Ts= 600°C, and finally stopped increasing above Ts= 600°C. The maximum preferred orientation and best crystallinity of the films were obtained at Ts= 550°C.
THE SOCIAL SIGNIFICANCE OF INCOME DISTRIBUTION STATISTICS
Authors: Bentzel Ragnar
Published: March 2005

In both political discussions and scientific literature the income distribution has come to occupy a central position for the consideration of social welfare and economic equalization. It has been assumed that an individual's income reflects his consumption opportunities and therefore his standard of living or economic welfare. The thesis of this paper is, however, that there are reasons for being quite pessimistic about drawing meaningful conclusions from income distribution data. As illustrated by the use of Swedish data, the distribution of income gives an extremely incomplete picture of the distribution of consumption for a wide variety of definitional and statistical reasons. The distribution of consumption, furthermore, cannot be transformed into a corresponding distribution of welfare, since there is no well defined concept of welfare. The treatment of public consumption in empirical analysis of the distribution of welfare also raises problems. The paper closes with the presentation of the conceptual basis for an alternative to the traditional method of analyzing the distribution of income.
Bond Strength of Composite to Alloy Treated With Bonding Systems
Authors: Chang Jeffrey C. , Powers John M. , Hart Deborah
Published: March 2005

Purpose The in‐vitro bond strengths of a composite bonded to a nickel‐chromium‐beryllium alloy treated by eight bonding systems were measured after three storage conditions.

Materials and Methods Nickel‐chromium‐beryllium alloy samples were treated by eight commercial bonding systems including adhesive composite cements, all‐purpose bonding agents, and silica‐coating systems. A composite was bonded to the alloy samples. Sample groups were stored in water for 24 hours at 23°C, or thermocycled, or stored for 6 months at 23°C and then debonded in tension.

Results Bond strengths after 24 hours storage were: adhesive composite cements, 14.2 to 22.1 MPa; all‐purpose bonding agents, 11.4 to 14.6 MPa; and silica‐coating systems, 18.6 to 20.2 MPa. Bond strengths after thermocycling were: adhesive composite cements, 12.6 to 20.6 MPa; all‐purpose bonding agents, 9.9 to 17.7 MPa; and silica‐coating systems, 11.1 to 19.2 MPa. Bond strengths after 6 months were: adhesive composite cements, 12.0 to 13.1 MPa; all‐purpose bonding agents, 8.7 to 14.1 MPa; and silica‐coating systems, 14.8 to 18.4 MPa.

Conclusions Only two bonding systems showed decreased bond strength after thermocycling, as compared with 24 hours' storage; whereas four bond systems showed decreased bond strength after 6 months' storage. Bond strengths measured after thermocycling were not predictive of those measured after 6 months' storage.
The Dental Student as Technician: An 18‐Year Follow‐Up of Preclinical Laboratory Programs
Authors: Weintraub Annette M. , Weintraub Gerald S.
Published: March 2005

In 1977, a survey of American and Canadian dental schools was conducted by Weintraub to determine the delegation of laboratory procedures in preclinical and clinical complete and removable partial denture programs. This was performed in light of challenges raised to the value of requiring dental students, rather than laboratory technicians, to perform the various laboratory procedures involved in the fabrication of complete and removable partial dentures. Since 1977, the rate of edentulism has declined in the United States, and fewer edentulous patients have sought regular dental care. In addition, approximately 20% fewer curriculum hours have been spent in dental schools in removable prosthodontic instruction; a declining number of graduating dental students have felt comfortable with their level of knowledge of removable prosthodontics, especially complete dentures, and have performed fewer removable prosthodontic procedures in practice because of a perceived lack of treatment cost‐effectiveness. The present study, an 18‐year follow‐up to the 1977 survey, was designed to determine if such trends toward a deemphasis on removable prosthodontic treatment have affected the mechanisms of instruction in and the extent to which dental schools instruct students about removable prosthodontics laboratory procedures. The 1995 survey was mailed to 53 American dental schools. Forty‐six schools returned the completed survey, for a response rate of 87%. Results showed that the proportion of schools with removable prosthodontic preclinical programs, especially those in removable partial dentures, increased, as did the relative amount of material presented to students in these programs. This was accomplished primarily through the enhancement of laboratory technician support, both in‐house and commercial, of student preclinical removable prosthodontic laboratory procedures. The conflict between these outcomes and the call by the dental community, as well as that of the 1995 Institute of Medicine Study, for a reduced emphasis on teaching students about the technical details involved in removable prosthesis fabrication is recognized and explored.