bluuebunny/crossref_metadata_2025 huggingface dataset:
Lithium-aluminum-carbonate-hydroxide hydrate coatings on aluminum alloys: Composition, structure, and processing bath chemistry
Authors: Drewien C.A. , Eatough M. O. , Tallant D. R. , Hills C. R. , Buchheit R. G.
Published: March 2008

A new corrosion resistant coating, being designed for possible replacement of chromate conversion coatings on aluminum alloys, was investigated for composition, structure, and solubility using a variety of techniques. The stoichiometry of the material, prepared by immersion of 1100 Al alloy into a lithium carbonate-lithium hydroxide solution, was approximately Li2Al4CO3(OH)12 · 3H2O. Processing time was shown to be dependent upon the bath pH, and consistent coating formation required supersaturation of the coating bath with aluminum. The exact crystal structure of this hydrotalcite material, hexagonal or monoclinic, was not determined. It was shown that both the bulk material and coatings with the same nominal composition and crystal structure could be formed by precipitation from an aluminum supersatured solution of lithium carbonate.
Effects of TiO2 on the microstructure and mechanical properties of Al2O3/ZrO2 composites
Authors: Hwang Chii-Shyang , Chang Yu-Jing
Published: March 2008

The microstructure and mechanical properties of hot-pressed zirconia-toughened alumina (ZTA), fabricated from the ZTA powders containing (Zr, Ti)O2 in Ar gas were investigated. In hot-pressed ZTA, the presence of Ti concentration in the grains of Al2O3 or (Zr, Ti)O2 was analyzed by the energy dispersive spectroscopy (EDS) attached to the analytical electron microscope (AEM) apparatus. Experimental results showed that some Ti ions diffused to the grain boundary and into the Al2O3 grains, thereby enhancing the densification of hot-pressed ZTA. It was possible to retain tetragonal ZrO2 at room temperature in the ZTA specimens containing ≥5.5 mol% TiO2 and hot pressed at 1350 °C for 1 h. The bending strength and toughness of hot-pressed ZTA were enhanced by the addition of TiO2.
In situ characterization of vapor phase growth of iron oxide-silica nanocomposites: Part I. 2-D planar laser-induced fluorescence and Mie imaging
Authors: McMillin Brian K. , Biswas Pratim , Zachariah Michael R.
Published: March 2008

Planar laser-based imaging measurements of fluorescence and particle scattering have been obtained during flame synthesis of iron-oxide/silica superparamagnetic nanocomposites. The theory and application of laser-induced fluorescence, the spectroscopy of FeO(g), and the experimental approach for measurement of gas phase precursors to particle formation are discussed. The results show that the vapor phase FeO concentration rapidly rises at the primary reaction front of the flame and is very sensitive to the amount of precursor added, suggesting nucleation-controlled particle growth. The FeO vapor concentration in the main nucleation zone was found to be insensitive to the amount of silicon precursor injected, indicating that nucleation occurred independently for the iron and silicon components. Light scattering measurements indicate that nanocomposite particles sinter faster than single component silica, in agreement with TEM measurements.
Al2O3/Al particle-reinforced aluminum matrix composite by displacement reaction
Authors: Hanabe M. R. , Aswath P. B.
Published: March 2008

The development of a novel Al matrix composite is described based on a simple displacement reaction when an SiO2 particulate preform is brought into contact with liquid Al at temperatures between 1273 and 1373 K. This interaction leads to the wetting of the SiO2 particles by Al and its eventual transformation to a composite with Al2O3/Al particles in an Al matrix. Infiltration of the preform as induced by this reaction takes place with the simultaneous formation of the Al2O3/Al particles in situ. Synthesis of engineered multiphase composites, wherein reinforcements of other materials incorporated into the preform and reacted with liquid Al, is also presented.
Y2BaCuO5addition and its effects on critical currents in large grains of YBa2Cu3O7–δ: A quantitative microstructural study
Authors: Chopra Manoj , Chan Siu-Wai , Meng R. L. , Chu C. W.
Published: March 2008

The addition of Y2BaCuO5(211) particles to large grain melt textured YBa2Cu3O7–δ(Y123) has significantly improved the critical current density (Jc) of this material. Here, a systematic quantitative analysis on the effects of the 211 addition was performed on a microscopic scale with a systematic variation of the initial volume percent of 211. From the correlation between critical current measurements and quantitative microscopy of both (001) and (110) sections, a maximum value ofJcis observed, corresponding to a measured Y123 volume percent of 20% ± 3%. Accounting for the loss of liquid phase for the present processing, the corresponding optimum initial volume of 211 for the highest measuredJcis 40%. Further comparison between the weightedJcand the true flux pinning force (Fp) also shows a maximum pinning force for an initial 211 addition of 40%. Although the weightedJcstarts to decrease with an initial 211 volume of above 40%, the pinning efficiency at higher magnetic fields (2–4 T) of the superconducting Y123 matrix was actually improved with an ever increasing 211 addition to at least 50%. Though an increasing addition of 211 is effective in producing efficient flux pinning sites in the Y123 matrix, percolation paths in the Y123 matrix become limited for supercurrent. Hence, a measured 211 volume corresponding to 80% 211 is proved to give the best possible critical current density. Furthermore, crack opening and crack spacing of the superficial cracks are found to decrease with an increasing 211 addition and with a decreasing 211 interparticle spacing. The penetration and surface length of each of these superficial cracks are hence reduced, which leads to a better electrical connectivity in the Y123 matrix.
Material removal and damage formation mechanisms in grinding silicon nitride
Authors: Xu Hockin H. K. , Jahanmir Said , Ives Lewis K.
Published: March 2008

Surface grinding was performed on two silicon nitrides with different microstructures. The ground surfaces of both materials were observed with scanning electron microscopy (SEM) to consist of areas of microfracture, smeared areas, and areas covered with fine debris particles. It was determined that microfracture is the primary mechanism for material removal. Subsurface grinding damage was revealed by a bonded-interface technique to take the form of median-type cracks extending from the plastic zones. Distributed intergranular microcracks and intragrain twin/slip bands were observed within the plastic zones. The strengths of transverse-ground specimens were measured in four-point flexure. For the silicon nitride with a fine grain size and a mildly rising toughness-curve, grinding damage resulted in a drastic strength degradation compared to polished specimens. In contrast, the silicon nitride with large and elongated grains and a steeply rising toughness curve showed relatively little strength loss. The relationship between the ceramic microstructure and the damage tolerance in abrasive machining is discussed in light of these results.
Evolution of mechano-chemistry and microstructure of a calcium aluminate-polymer composite: Part II. Mixing rate effects
Authors: Tan L. S. , McHugh A. J. , Gülgün M. A. , Kriven W. M.
Published: March 2008

Microstructure, microchemistry and mechanical properties of hardened macro-defect-free (MDF) composites processed at various rotor rates in a Banbury mixer were investigated. A quiescently formed calcium aluminate-polyvinyl alcohol composite served as a substitute for an unmixed system. Results from the Banbury studies in conjunction with microchemical analysis of the unmixed composite showed evidence that the polymer-particle interaction is a mechanically induced crosslinking reaction. The rate of the mechano-chemistry increases with mixing speeds. Scanning electron micrographs (SEM) and transmission electron micrographs (TEM) of hardened composites mixed for 15 min at 30, 50, 100, and 200 rpm indicate that much of the mechanical strength of MDF is due to the crosslinked interphase zones that blanket the cement grains. Stresses in the paste due to mixing can destroy the interphase layer, leading to a weaker hardened composite. Microchemical analysis revealed that the mechano-chemistry of the system did not vary with changes in the mixing conditions studied.
Effects of secondary pretreatments of substrate on the nucleation of diamond film
Authors: Yang W. S. , Je Jung Ho
Published: March 2008

The effects of secondary pretreatments on diamond nucleation were investigated for the Si substrates pretreated by the diamond abrasion. When the substrate was just abraded with diamond powder, the nucleation density of diamond was 7 × 108/cm2. However, the nucleation density was found to be greatly decreased by various secondary pretreatments except by one wet chemical etching method. The nucleation density was reduced to 3 × 107/cm2 by the chemical etching (I), to 7 × 106/cm2 by the H2 plasma etching, and to ∼104/cm2 by the Ar sputtering, or O2 plasma etching. It was very slightly reduced to 3 × 108/cm2 by the chemical etching (II). The effects of secondary pretreatments in reducing the nucleation density were found to be very closely related to the removal of diamond seeds rather than topographic sites or structural defects. Therefore, diamond seeds generated by the diamond abrasion are considered as the main nucleation sites of diamond.
Phase analysis of seeded and doped PbMg1/3Nb2/3O3 prepared by organic solution of citrates
Authors: Carvalho J. C. , Paiva-Santos C. O. , Zaghete M. A. , Oliveira C. F. , Varela J. A. , Longo E.
Published: March 2008

PbMg1/3Nb2/3O3 (PMN) prepared by organic solution of citrates was analyzed by the Rietveld method to determine the influence of seeds and dopants on the perovskite and pyrochlore phase formation. It was observed that pyrochlore phase formation increases with an increase in calcination time when no additives are included during the preparation. It was also observed that a greater amount of perovskite phase appeared in doped or seeded samples. The fraction of perovskite phase increased from 88 mol% in pure sample to ∼95 mol% in doped and seeded samples calcined at 800 °C for 1 h. It is clear that the addition of dopants or seeds during PMN preparation can enhance the formation of perovskite phase.
A model for evaluating and predicting high-temperature thermal expansion
Authors: Wang Kai , Reeber Robert R.
Published: March 2008

In this paper, a new set of experimental data, αVKTV, representing the partial temperature derivative of the work done by the thermal pressure of the solid, is fitted by n terms of a modified Einstein model. Experimental data show that αVKTV, not αVKT, approaches a constant value at high temperature. Based on the observed linear relationship of isothermal bulk modulus with temperature at high temperature, thermal expansion can be evaluated by fitting αVKTV data. Our previous results have shown that at low temperature or for materials with less variable bulk modulus and expansivity, thermal expansion data can be simply approximated by an n term Einstein model. More generally and for many materials, αVKTV data resemble an isochoric specific heat curve. With this method, thermal expansion can be predicted at high temperatures from low and intermediate temperature range data. With accurate thermal expansion data, high temperature bulk moduli can also be predicted.
Aluminum nitride buffer layer for diamond film growth
Authors: Godbole V. P. , Narayan J.
Published: March 2008

The role of aluminum nitride (AlN) as a buffer layer on the nucleation and growth of diamond on silicon and steel substrates during hot filament chemical vapor deposition (HF-CVD) has been investigated systematically. The scanning Auger electron microscopy (AES) is employed to study chemistry and content of carbon on the surface and in subsurface regions of AlN as a function of HF-CVD parameters. It is found that AlN offers an excellent diffusion barrier for carbon over a wide range of temperature and hydrocarbon content of CVD gas environment, with simultaneous inhibition of graphitization. It also facilitates nucleation of diamond phase. The surface reactions between AlN and carbon are discussed in terms of hydrogen-assisted phase transformations. We have developed a two-step procedure to obtain a continuous diamond film on steel substrates. The characteristic features of AlN have been exploited to obtain adherent and graphite-free diamond deposits on various types of steels, including low carbon steel, tool steel, high speed steel, and bearing steel.
The self-propagation high-temperature synthesis of ultrafine high purity tungsten powder from scheelite
Authors: Jung J. C. , Ko S. G. , Won C. W. , Cho S. S. , Chun B. S.
Published: March 2008

High-purity tungsten was prepared by the self-propagating high-temperature synthesis (SHS) process from a mixture of CaO · WO3 and Mg. The complete reduction of CaO · WO3 required a 33% excess of magnesium over the stoichiometric molar ratio Mg/CaO · WO3 of 3: 1. The MgO and CaO in the product were leached with an HCl solution. The product tungsten had a purity of 99.980% which was higher than that of the reactants. The high purity results because the nontungsten reactants and products are volatilized by the high temperatures generated during the rapid exothermic SHS reaction and are dissolved during HCl leaching of the product.
Boron loss in furnace- and laser-fired, sol-gel derived borosilicate glass films
Authors: Taylor D. J. , Dent D. Z. , Braski D. N. , Fabes B.D.
Published: March 2008

Borosilicate glass films were made by the sol-gel method from tetraethoxysilane and trimethylborate precursors. The precursor or glass composition at each stage of processing was analyzed to determine the sources of boron loss. The films were heated in a furnace and with a laser to compare boron volatilization by the two heating methods. The films were characterized by infrared spectroscopy, ellipsometry, induction-charged plasma spectroscopy, and Auger microscopy. The highest losses of boron occurred during coating and low temperature (<500 °C) furnace firing. Films with the highest boron concentrations were made by dip coating and rapid firing, either with a laser or by placing them into a hot furnace. Infrared spectroscopy revealed Si–O–B bonds, indicating incorporation of boron into the borosilicate glass structure for laser- and furnace-fired films.
Room temperature perovskite production from bimetallic alkoxides by ketone assisted oxo supplementation (KAOS)
Authors: Gaskins B.C. , Lannutti J.J.
Published: March 2008

Barium titanate has been prepared at room temperature from a well-characterized crystalline barium titanium oxo alkoxide by reaction with acetone. An aldol condensation apparently supplies oxygen to condensing oxo alkoxide clusters. Transmission electron microscopy confirms that the crystallites so formed are dense and perfect with an average size of approximately 85 Å. Characterization of reactants and products provides a tentative understanding of structural evolution and the intermediates of the transformation. Crystalline SrTiO3 and BaZrO3 were also formed at room temperature by this same method.
Analysis of nanoindentation load-displacement loading curves
Authors: Hainsworth S. V. , Chandler H. W. , Page T. F.
Published: March 2008

Nanoindentation load-displacement curves provide a “mechanical fingerprint” of a materials response to contact deformation. Over the last few years, much attention has been focused on understanding the factors controlling the detailed shape of unloading curves so that parameters such as true contact area, Young's modulus, and an indentation hardness number can be derived. When the unloading curve is well behaved (by which we mean approximating to linear behavior, or alternatively, fitting a power-law relationship), then this approach can be very successful. However, when the test volume displays considerable elastic recovery as the load is removed [e.g., for many stiff hard materials and many inhomogeneous systems (e.g., those employing thin hard coatings)], then the unloading curve fits no existing model particularly well. This results in considerable difficulty in obtaining valid mechanical property data for these types of materials. An alternative approach, described here, is to attempt to understand the shapes of nanoindentation loading curve and thus quantitatively model the relationship between Young's modulus, indentation hardness, indenter geometry, and the resultant maximum displacement for a given load. This paper describes the development and refinement of a previous approach by Loubet et al1 originally suggested for a Vickers indenter, but applied here to understand the factors that control the shape of the loading curve during nanoindentation experiments with a pointed, trigonal (Berkovich) indenter. For a range of materials, the relationship P = Kmδ2 was found to describe the indenter displacement, δ, in terms of the applied load P. For each material, Km can be predicted from the Young's modulus (E) and the hardness (H). The result is that if either E or H is known, then the other may be calculated from the experimental loading curve. This approach provides an attractive alternative to finite element modeling and is a tractable approach for those cases where analysis of unloading curves is infeasible.
Inversion domain boundaries in ZnO ceramics
Authors: McCoy M. A. , Grimes R. W. , Lee W. E.
Published: March 2008

Inversion domain boundaries (IDB's) in ZnO ceramics, associated with Sb2O3 doping, have been characterized using a range of electron microscopy techniques. The IDB's lie primarily on basal planes, but frequently are stepped along prismatic planes. The basal IDB can be characterized as (i) an inversion that causes an antisite exchange of cations and anions across the boundary, (ii) an effective displacement of the sixfold screw axis in the wurtzite structure vectors by a translation of 1/3 and (iii) a displacement normal to the boundary. Significant Sb segregation is detected in the basal IDB segments in agreement with previous work, and in ceramics doped with Sb2O3 and Bi2O3. These IDB's contained both Sb and Bi, suggesting that while Bi does not participate in IDB nucleation, it resides in the boundary. Comparison of experimental and calculated HREM images suggests that the IDB is composed of a monolayer of Type I (111) zinc antimonate spinel, consisting of a single layer of octahedrally coordinated zinc and antimony cations.
Hybrid materials based on the reaction of polyorganophosphazenes and SiO2 precursors
Authors: Guglielmi M. , Brusatin G. , Facchin G. , Gleria M.
Published: March 2008

New molecular composite materials can be prepared based on an inorganic oxide network and an organic polymer. The polymeric component generally requires low process temperatures, due to the presence of the organic backbone or side groups. A sol-gel process therefore is suitable for synthesizing the inorganic component by dissolving soluble polymers into sol-gel precursor solutions in order to obtain ceramic and polymeric solid phases. In this work polyorganophosphazenes were used because they have many technologically interesting properties (chemical, optical, electrical, mechanical). The methods to obtain covalent bonds between polymer and inorganic network and to obtain homogeneous, transparent hybrid materials without phase separation were studied. It was possible to avoid phase separation by preparing phosphazenes containing free hydroxyl functions and by adequately choosing the experimental conditions.
Effect of interface design on high-temperature failure of laminated composites
Authors: Chen Z. , Mecholsky J. J. , Hu S.
Published: March 2008

The fracture strength and toughness of alumina can be increased by lamination with strategically placed nickel layers and with a modified Ni/Al2O3 interface through tape casting. In order to examine the potential of this type of laminated composite in high temperature applications, the laminates were tested at elevated temperatures. This paper describes how a modified tortuous interface, instead of a smooth interface, increases the creep resistance of the laminates. Interface modification can control high temperature laminate behavior and is critical to successful composite design.
Protective coatings of nanophase diamond deposited directly on stainless steel substrates
Authors: Davanloo F. , Park H. , Collins C. B.
Published: March 2008

Composed of sp3 bonded nodules of carbon, nanophase diamond films are deposited in vacuum onto almost any substrate by condensing carbon ions carrying keV energies. These multiply charged ions are obtained from the laser ablation of graphite at intensities in excess of 1011 W cm−2. The high energy of condensation provides both the chemical bonding of such films to a wide variety of substrates and low values of residual compressive stress. Coatings of 2–5 μm thickness have extended lifetimes of materials such as Si, Ti, ZnS, ZnSe, and Ge against the erosive wear from high-speed particles by factors of tens to thousands. In this research emphasis has been placed on studies of the bonding and properties realized by the direct deposition of nanophase diamond films on stainless steel substrates. Examinations of interfacial layers showed deep penetrations of carbon atoms into steel substrates. Resistances to low and high impact wear estimated by a tumbler device and a modified sand blaster, respectively, and results indicated significant increases in the lifetime of stainless steel samples. The characterization studies in this work demonstrated nanophase diamond as an attractive material for use as a protective coating in current industrial applications.
Microstructural development in sol-gel derived lead zirconate titanate thin films: The role of precursor stoichiometry and processing environment
Authors: Lefevre M. J. , Speck J. S. , Schwartz R. W. , Dimos D. , Lockwood S. J.
Published: March 2008

The role of precursor stoichiometry and local firing environment on the microstructural development of sol-gel derived lead zirconate titanate (PZT) thin films was investigated. Typically, excess Pb is added to films to compensate for PbO volatilization during heat treatment. Here, it is shown that the use of stoichiometric precursors with either a PbO atmosphere powder or a PbO overcoat during the crystallization heat treatment is an attractive and viable alternative method for control of film stoichiometry. Using these approaches, we have fabricated single phase perovskite thin films with microstructures and electrical properties (Pr ∼ 36 μC/cm2 and Ec ∼ 45 kV /cm) comparable to those of films using optimized solution chemistries and excess Pb additions. The potential advantage of increasing PbO partial pressure, or activity, during firing versus excess Pb additions is discussed from the standpoint of a proposed crystallization scenario based on the kinetic competition between Pb loss and the nucleation and growth rates of the perovskite phase.
Reduced thermal decomposition of OH-free LiNbO3 substrates even in a dry gas atmosphere
Authors: Nagata Hirotoshi , Sakamoto Toshihiro , Honda Hideki , Ichikawa Junichiro , Haga Eungi Min , Shima Kaori , Haga Nobuhiko
Published: March 2008

A thermal diffusion process of Ti into a LiNbO3 substrate for optical waveguides has generally been carried out under a wet gas atmosphere in order to prevent undesirable Li outdiffusion. In this work, such thermal decomposition was confirmed to be significantly suppressed for an OH-free LiNbO3 substrate, even after a dry atmosphere annealing. No extra x-ray diffraction peak for LiNb3O8 was detected from the OH-free substrate after 10 h of annealing at 1000 °C in a dry O2. Furthermore, the surface morphology of this sample, and as well an unannealed one, were smooth. In a conventional LiNbO3 substrate containing many OH ions, subjected to a similar dry annealing, the presence of the LiNb3O8 phase and a surface coarsening were observed.
Myoplasty for Congenital Macrostomia
Authors: Gleizal Arnaud , Wan Derrick C. , Kwan Matthew D. , Beziat Jean-Luc
Published: March 2008

Objective:

To describe the different myoplasty techniques that could be used for limited commissural reconstruction.

Methods:

Twelve cases of congenital macrostomia are reported, with different cleft lengths and termination sites. For each case, an orbicular myoplasty was performed, and in the case of extension to the area of the tragus or tonsillar pillars, a masseteric myoplasty or pharyngoplasty was performed. Functional and aesthetic results were analyzed.

Results:

Functional results were excellent, with normal phonation, facial expression, and deglutition in the case of posterior extension. Aesthetic results were good, with only two cases of skin fasciculation during facial movement.

Conclusions:

Myoplasty in macrostomia could be limited to an orbicular reorientation in the case of a short cleft or can include a masseteric myoplasty or pharnygoplasty should the cleft extend further. Analyzing 90 reported cases of congenital macrostomia in the world literature, an important point has emerged. In some cases, the cleft could continue sagittally to the tonsillar pillars or laterally, distal to the anterior border of the masseter, to the region of the tragus. Repair in these cases requires reconstruction of the tonsillar pillars and masseteric repair in addition to orbicular removal. No reports in the world literature have referred to these other myoplasties that could be necessary, even if such pathology is very rare. In addition, no classification of congenital macrostomia was found in the world literature. We therefore propose a surgical classification of macrostomia relative to the nature of myoplasty required.
Birth Prevalence of Cleft Lip and Palate in Northern Ireland (1981 to 2000)
Authors: Gregg T. A. , Leonard A. G. , Hayden C. , Howard K. E. , Coyle C. F.
Published: March 2008

Objective:

The prevalence of cleft lip and/or palate (CL/P) in Northern Ireland (NI) was last reported for 1980 through 1990. This study was undertaken to update the prevalence of CL/P in NI for the 20-year period 1981 to 2000, to determine the pattern of prevalence, and to report the proportion of different cleft types and sex distribution.

Design:

Retrospective, population-based analysis.

Patients/participants:

All live born children with CL/P in NI from 1981 to 2000 were included. A total of 750 cases were identified. Resident births outside NI, stillbirths, abortuses, and children born with atypical orofacial clefts were excluded. Those with syndromes and submucous clefts were included in the study.

Results:

The overall prevalence of children born with CL/P within NI for the period 1981 to 2000 was 1.47 per 1000 live births, or 1:682. This was consistent with the findings reported by other U.K. studies. There were no significant changes in the prevalence rates over any 5-year period. No significant seasonality trends were noted. Clefts of the palate only were always in the majority. More boys than girls were affected by cleft lip with or without cleft palate. There was a significant left-sided predilection for unilateral clefting of the lip.

Conclusions:

There have been no significant changes in the birth prevalence of children born with CL/P or the distribution or laterality of cleft type in the NI population during the past 20 years.
Abnormal Maxillary Trapezoid Pattern in Human Fetal Cleft Lip and Palate
Authors: Kim Soung Min , Lee Young Joon , Lee Sang Shin , Kim Yeon Sook , Lee Suk Keun , Kim Il Bong , Chi Je Geun
Published: March 2008

Objective:

To elucidate abnormal growth patterns of human fetal maxillae with cleft lip and palate (CLP).

Subject:

A total of 71 fetal maxillae with CLP were obtained from aborted human fetuses.

Method:

Dimensions of the maxillary trapezoid (MT), formed by the maxillary primary growth centers (MxPGC), were taken from radiographic images. The CLP dimensions were compared with maxillary trapezoid dimensions of normal fetuses from a previous study (Lee et al., 1992).

Main Outcome Measures:

Cleft lip subjects without a cleft palate, unilateral cleft lip-alveolar cleft or cleft palate (UCL+A/UCLP), and bilateral cleft lip-alveolar cleft or cleft palate (BCL+A/BCLP) displayed abnormal MT patterns. MT abnormalities were most marked in the BCL+A/BCLP cohort.

Results:

The MT growth of prenatal CLP maxillae was severely arrested, resulting in abnormal MT shape on palatal radiograms. BCL+A/BCLP subjects had a more protruded nasal septum than subjects with other types of CLPs, while UCL+A/UCLP subjects showed severe deviation of the protruded nasal septum toward the noncleft side. Cleft lip-only subjects also exhibited abnormal MT growth.

Conclusion:

MT is primarily involved in CLPs, so that the MT shape could be utilized as a sensitive indicator for the analysis of maxillary malformation in different types of CLPs.
Hearing Thresholds in Newborns with a Cleft Palate Assessed by Auditory Brain Stem Response
Authors: Viswanathan Narayanan , Vidler Michael , Richard Bruce
Published: March 2008

Objective:

To objectively estimate the extent of hearing loss in infants with cleft palate and to measure the incidence of hearing loss.

Design:

Retrospective consecutive case note review.

Setting:

Tertiary institutional regional referral center for cleft lip and palate.

Patients, Participants:

Consecutive cases of 90 infants with cleft palate who underwent auditory brain stem response (ABR) threshold estimation.

Interventions:

ABR threshold estimation during natural sleep in infants with cleft palate under 2 months of age.

Main Outcome Measures:

Hearing level thresholds as estimated by auditory brain stem response and categorized as normal (< 25 ≤ 35 dB nHL), mild (> 35 ≤ 45 dB nHL), moderate (> 45 ≤ 65 dB nHL), severe (> 65 ≤ 90 dB nHL), and profound (> 90 dB nHL) hearing loss.

Results:

Hearing loss was present in 82% of the infants tested. Most of the hearing loss was conductive (89%), mild (86%), and bilateral (84%). Average age of ABR threshold estimation was 48.5 days. In 22% of infants there was an associated syndrome. The mean air conduction thresholds for the right and left ear were 40 and 39.7, respectively.

Conclusion:

The incidence of hearing loss in a cohort of cleft palate infants has been objectively estimated by auditory brain stem response thresholds and was found to be very high (82%).
A Population-Based Evaluation of Antenatal Diagnosis of Orofacial Clefts
Authors: Russell Kathleen A. , Allen Victoria M. , MacDonald Mary E. , Smith Kirsten , Dodds Linda
Published: March 2008

Objectives:

To evaluate the changes in prevalence and antenatal detection of cleft lip with or without cleft palate and isolated cleft palate and to describe the association between anomalies and rates of antenatal diagnosis in Nova Scotia from 1992 to 2002.

Design:

This population-based cohort study employed the Nova Scotia Atlee Perinatal Database, the Fetal Anomaly Database, and IWK Cleft Palate Database in Halifax, Nova Scotia, Canada.

Outcome Measures:

Cleft type, mode of diagnosis, and associated abnormalities of orofacial clefts for liveborn infants, stillbirths, and second trimester terminations of pregnancy between 1992 and 2002 were determined.

Results:

There were 225 fetuses identified as having orofacial clefts. The overall prevalence of clefts was 2.1 in 1000 live births, and this prevalence did not change with time. The overall antenatal detection of cleft lip with or without cleft palate was 23%; however, there was improvement in detection of cleft lip with or without cleft palate from the years 1992 to 1996 (14%) to the years 1997 to 2002 (30%, p  =  .02). No isolated cleft palates were detected antenatally. Associated structural anomalies were seen in 34.2% of cases with orofacial clefts, and chromosomal abnormalities were associated with 9.8%.

Conclusions:

The prevalence of orofacial clefts in Nova Scotia has not changed from 1992 to 2002. The proportion of antenatally diagnosed cleft lip with or without cleft palate in Nova Scotia is consistent with rates reported in the literature and has increased from 1992 to 2002.
Incidence of Oronasal Fistulae and Velopharyngeal Insufficiency after Cleft Palate Repair: An Audit of 211 Children Born between 1990 and 2004
Authors: Phua Yun Shan , de Chalain Tristan
Published: March 2008

Objective:

We present an audit of primary cleft palate surgery at our unit, including rates of oronasal fistula development, speech outcomes, and rates of velopharyngeal insufficiency requiring secondary surgery.

Design:

A retrospective study of patients with all cleft palate types, born between January 1990 and December 2004, who underwent primary palatoplasty at Middlemore Hospital, Auckland, New Zealand.

Patients:

The study included 211 patients, collectively operated on by five different surgeons.

Results:

The overall rate of true fistula development was 12.8% over a mean follow-up period of 4 years 10 months. The incidence of true fistulae that required surgical repair was 8.1%. Fistula rates were higher for more severe degrees of clefting but were not affected by gender or type of surgical repair. Overall, 31.8% of the study population had some degree of hypernasality following primary palatoplasty. Secondary surgery for velopharyngeal insufficiency was required in 13.3% of patients. Following surgical correction of velopharyngeal insufficiency, no patients were reported to have appreciable hypernasality and 21.7% were reported to have mild hypernasality, a result comparable to previously published audits. The requirement for secondary surgery was higher in patients with more severe clefts.

Conclusion:

Our results are comparable to other recent studies. We believe that highly coordinated cleft care helps ensure such outcomes. These data provide a benchmark against which we can measure future performance in our attempts to improve outcomes of cleft repair.
Characteristics of 2733 Cases Diagnosed with Deformational Plagiocephaly and Changes in Risk Factors over Time
Authors: McKinney Christy M. , Cunningham Michael L. , Holt Victoria L. , Leroux Brian , Starr Jacqueline R.
Published: March 2008

Objectives:

To describe infant and maternal characteristics among infants with plagiocephaly and to quantify time trends in potential risk factors for plagiocephaly.

Design:

Case-only study. We described the characteristics of individuals born between 1987 and 2002. We also compared characteristics of individuals born from 1987 through 1990, before the American Academy of Pediatrics 1992 sleep-position recommendations, with those of individuals born from 1991 to 2002.

Setting:

Children's Craniofacial Center at Children's Hospital and Regional Medical Center in Seattle, Washington.

Participants:

Subjects included 2733 infants diagnosed with deformational plagiocephaly or brachycephaly before 18 months of age who were born from 1987 to 2002.

Main Outcome Measure:

Descriptive statistics, odds ratios, and 95% confidence intervals.

Results:

Among individuals born from 1991 to 2002, 91.6% had occipital-only flattening, 17.2% were brachycephalic, 67.7% were boys, and 9.9% were multiple birth infants. As compared with individuals born from 1987 through 1990, those born from 1991 to 2002 were more apt to be a multiple birth (odds ratio [OR] 3.4, 95% confidence interval [CI]: 0.8, 14.1) and to have a mother ≥35 years of age (OR, 3.2; 95% CI, 1.4 to 7.3); they were hospitalized less commonly at birth for 4 or more days (OR, 0.02; 95% CI, 0.01 to 0.06).

Conclusions:

Several risk factors for plagiocephaly were more common among individuals born after the 1992 American Academy of Pediatrics sleep-position recommendations. These results are consistent with the explanation that supine sleeping modifies the association between such risk factors and plagiocephaly. Further studies with a control group are needed to validate this conclusion.
Caregiver and Patient Reported Outcomes after Repair of Cleft Lip and/or Palate in the Philippines
Authors: Sharp Helen M. , Canady John W. , Ligot Fernando A. C. , Hague Rebecca A. , Gutierrez Johcille , Gutierrez Johnny
Published: March 2008

Objectives:

To establish the feasibility of conducting outcomes research among patients treated during a medical mission and to identify the salient outcomes for patients and caregivers in one region of the Philippines.

Design And Setting:

Prospective structured interview conducted in or near participants’ homes on the island of Cebu, Philippines.

Participants:

Individuals who had surgery at least 6 months earlier within the study region were eligible. Recipients of surgery were located from surgical records and by word of mouth.

Main Outcome Measures:

(1) Proportion of individuals located. (2) Primary outcomes of oral cleft repair identified for the sample.

Results:

Of 99 people on a surgical list, 52 (53%) were located, eight were excluded (ineligible, unavailable, or inaccessible), and 44 agreed to participate in the study. Ten participants were identified via word of mouth. Seventy-five interviews were conducted (21 caregiver–patient pairs, one adolescent, and 32 caregivers of a child <7 years). Nearly all participants (99%) would encourage others to pursue surgery. Open-ended questions were coded to identify primary outcomes: improved speech (52%), improved eating (25%), social benefits (14%), and improved appearance (6%). Caregivers (50%) and patients (68%) reported that improved speech was the most important change after surgery.

Conclusions:

Patients and caregivers ascribe positive changes related to cleft surgery. Outcomes research requires cooperation with local professionals who can communicate effectively. These data serve to demonstrate feasibility and as a model for future studies of treatment outcomes in follow-up to international medical missions.
Fully Bayesian Mixture Model for Differential Gene Expression: Simulations and Model Checks
Authors: Lewin Alex , Bochkina Natalia , Richardson Sylvia
Published: March 2008

We present a Bayesian hierarchical model for detecting differentially expressed genes using a mixture prior on the parameters representing differential effects. We formulate an easily interpretable 3-component mixture to classify genes as over-expressed, under-expressed and non-differentially expressed, and model gene variances as exchangeable to allow for variability between genes. We show how the proportion of differentially expressed genes, and the mixture parameters, can be estimated in a fully Bayesian way, extending previous approaches where this proportion was fixed and empirically estimated. Good estimates of the false discovery rates are also obtained.Different parametric families for the mixture components can lead to quite different classifications of genes for a given data set. Using Affymetrix data from a knock out and wildtype mice experiment, we show how predictive model checks can be used to guide the choice between possible mixture priors. These checks show that extending the mixture model to allow extra variability around zero instead of the usual point mass null fits the data better.A software package for R is available.
Distal Degenerative Sensory Neuropathy in a Long-Term Type 2 Diabetes Rat Model
Authors: Brussee Valentine , Guo GuiFang , Dong YingYing , Cheng Chu , Martinez José A. , Smith Darrell , Glazner Gordon W. , Fernyhough Paul , Zochodne Douglas W.
Published: March 2008

OBJECTIVE—Peripheral neuropathy associated with type 2 diabetes (DPN) is not widely modeled. We describe unique features of DPN in type 2 diabetic Zucker diabetic fatty (ZDF) rats.

RESEARCH DESIGN AND METHODS—We evaluated the structural, electrophysiological, behavioral, and molecular features of DPN in ZDF rats and littermates over 4 months of hyperglycemia. The status of insulin signaling transduction molecules that might be interrupted in type 2 diabetes and selected survival-, stress-, and pain-related molecules was emphasized in dorsal root ganglia (DRG) sensory neurons.

RESULTS—ZDF rats developed slowing of motor sciatic-tibial and sensory sciatic digital conduction velocity and selective mechanical allodynia with preserved thermal algesia. Diabetic sural axons, preserved in number, developed atrophy, but there was loss of large-calibre dermal and small-calibre epidermal axons. In diabetic rats, insulin signal transduction pathways in lumbar DRGs were preserved or had trends toward upregulation: mRNA levels of insulin receptor β-subunit (IRβ), insulin receptor substrate (IRS)-1, and IRS-2. The numbers of neurons expressing IRβ protein were also preserved. There were trends toward early rises of mRNA levels of heat shock protein 27 (HSP27), the α2δ1 calcium channel subunit, and phosphatidylinositol 3-kinase in diabetes. Others were unchanged, including nuclear factor-κB (NF-κB; p50/p105) and receptor for advanced glycosylation endproducts (RAGE) as was the proportion of neurons expressing HSP27, NF-κB, and RAGE protein.

CONCLUSIONS—ZDF type 2 diabetic rats develop a distal degenerative sensory neuropathy accompanied by a selective long-term pain syndrome. Neuronal insulin signal transduction molecules are preserved.
On Using Stochastic Curtailment to Shorten the SPRT in Sequential Mastery Testing
Authors: Finkelman Matthew
Published: March 2008

Sequential mastery testing (SMT) has been researched as an efficient alternative to paper-and-pencil testing for pass/fail examinations. One popular method for determining when to cease examination in SMT is the truncated sequential probability ratio test (TSPRT). This article introduces the application of stochastic curtailment in SMT to shorten the TSPRT without substantially compromising error rates. Unlike the TSPRT, the stochastically curtailed procedure exhibits an optimality property known as weak admissibility. Error bounds of the two methods are provided in terms of one another. In two simulation sets, the stochastically curtailed procedure considerably improved the average test length of an SMT with only a slight decrease in accuracy.
Thermophysical properties of Nd-, Er-, YNi-alloys
Authors: Plevachuk Yuriy , Sklyarchuk Vasyl , Hermann Regina , Gerbeth Gunter
Published: March 2008

Nd – Fe – B alloys are widely used in many technical applications due to their excellent permanent magnetic properties. YNi2B2C intermetallic compounds receive much attention because of the coexistence of superconductivity and magnetic ordering phenomena. Er2PdSi3 alloys with hexagonal AlB2-type crystallographic structure are of special interest because of their complex magnetic ordering, Kondo and heavy fermion behavior. The thermophysical properties (electrical conductivity, thermoelectric power, thermal conductivity and viscosity) of these liquid multicomponent intermetallic alloys have been measured in order to supply necessary information for crystal growth and casting processes. Good reproducibility of the results has been obtained.
Thermodynamic modeling of the Cu–Se system
Authors: Du Zhenmin , Guo Cuiping , Tao Mei , Li Changrong
Published: March 2008

The Cu – Se system was modeled by means of the CALPHAD technique. Considering two miscibility gaps of the liquid existed on each side of the compound Cu2Se, the associate model with the associate species “Cu2Se” was adopted to describe the Gibbs energy for the liquid and compared to the random solution model. The optimizing results showed that the thermodynamic model describing the liquid phase as a solution of Cu, Se and a “Cu2Se” associate fits well with the experimental data. The intermetallic compounds, Cu3Se2, α-CuSe, β-CuSe, γ-CuSe and CuSe2were treated as stoichiometric compounds. The com-pounds α-Cu2Se and β-Cu2Se, which have a homogeneity range, were treated as the formulae α-(Cu, Se)2Se and β-(Cu, Se)2Se by a two-sublattice model. A set of self-consistent thermodynamic parameters of the Cu – Se system was obtained.
Isothermal section at 773 K of the Gd–Er–Co ternary system
Authors: Zhou K. W. , Zhuang Y. H. , Zhang X. Y. , Li J. Q. , Zhu A. W. , Xia X. W.
Published: March 2008

An investigation of the isothermal section at 773 K of the Gd – Er – Co ternary system has been carried out by means of X-ray powder diffraction, metallographic analysis and differential thermal analysis techniques. At this temperature, a series of continuous solid solutions forming from the binary compounds in the Gd – Co and Er – Co systems characterized the phase diagram. The Curie temperatures of Gd1 – xEr
x
Co2 (x = 0, 0.2, 0.4, 0.6, 0.8) alloys have also been determined.
Influence of carbides and of the dendritic orientation on the thermal expansion of Ni-base, Co-base and Fe-base simple cast alloys
Authors: Berthod Patrice
Published: March 2008

Knowing how chemical composition and microstructure can influence the thermal expansion of high temperature alloys is of great importance. The behaviour of pure Ni, Co or Fe and of simple 30 wt.% Cr-containing cast alloys based on these elements, carbide-free or containing 0.8 wt.% C, were studied between 500°C and 1200°C. Special attention was given to the possible effect of the carbide and of the dendrite orientation. Thermal expansion coefficients are provided and compared with regard to the microstructure. The presence of Cr in the alloys leads to higher thermal expansions than for pure elements. The interdendritic carbides tend to reduce the alloys' thermal expansion behaviour by obstructing the allotropic dimensional phenomena or by plastically deforming the matrix in compression. The dendritic orientation seems to influence the thermal expansion of carbide-containing alloys.
Climate‐growth relationships of relict Pinus tabulaeformis at the northern limit of its natural distribution in northern China
Authors: Liang Eryuan , Eckstein Dieter , Liu Hongyan
Published: March 2008

Questions:

Sand storms from east Inner Mongolia are a major threat to the ecological safety of North China and actions are desirable to control further desertification. Small patches of relict Pinus tabulaeformis could play a major role in this. The climate signal recorded in the tree‐ring widths and the dates of past regeneration episodes of these trees growing at the northern border of their natural distribution are considered here.

Location:

Ortindag Sand Land in North China.

Methods:

We collected increment cores from relict P. tabulaeformis trees at five sites, built a standard tree‐ring chronology for each site and a regional tree‐ring chronology from the three longest site chronologies, analysed the tree growth/climate relationships and determined the germination years of the trees to recognize past regeneration dynamics.

Results:

Monthly precipitation and relative air humidity in the previous and current growing seasons are the major limiting factors for the radial growth of P. tabulaeformis. Years with a high frequency of absent tree rings are characterized by particularly extreme dry conditions. These results are supported by negative correlations between radial growth and monthly maximum temperature and evaporation during the growing season. In a 163‐year time series of precipitation from previous July to current June reconstructed from the tree rings, cycles with wave lengths of 2‐3, 17.4 and 20.5 years are significant.

Conclusion:

P. tabulaeformis trees are reliable recorders of high and low frequency variations of dry/wet environmental conditions in the Ortindag Sand Land. Their age structures within the forest patches prove that they regenerate preferentially in less dry periods.