bluuebunny/crossref_metadata_2025_split huggingface dataset:
STABILITY OF LEAD GLASSES AND POLARIZATION OF IONS*
Authors: Fajans Kasimir , Kreidl Norbert J. 
Published: June 2006

AbstractThe current theories of glass formation deal mainly with inorganic substances containing oxygen as the negatively charged component. A distinction has been made between those positively charged components which are considered as essential for the formation of the continuous network and those which fit into the interstices of the network and have only a secondary modifying effect on the properties of the glass. While the small and highly charged ions B3+, Si4+, and P5+, which exert a strong electrical attraction on oxygen, have been classified as typical network‐formers, the larger, only singly and doubly charged alkali and alkaline earth cations were considered as typical network‐modifiers. However, the behavior of Be2+ and Al3+ is intermediate between these extremes and shows that the classification is not precise. Furthermore, the following facts prove that the strength of the forces between the positive and negative components is not the decisive factor for glass formation: S6+ is not a glassformer, whereas PbO favors glass formation even though Pb2+ resembles Sr2+ in many other respects.It is suggested in the present paper that in the case of inorganic substances, the mutual polarization of ions is the common factor responsible for the stability of glasses. In those silicates which contain only cations of noble gas type, the decisive factor is the polarization of O2‐ by the strong field of the central cation Si4+. The high polarizability of the non‐noble gas type cation Pb2+ is considered responsible for the stability of lead glasses. Strong polarization effects diminish the symmetry of the constituent parts which have to move against each other in the process of crystallization. The lack of symmetry of the field of forces around the ions of inorganic substances as well as around the molecules of organic compounds like glycerol appears to be responsible for the high viscosity of the liquid at the solidification temperature and thus for the stability of the vitreous state.The tightness of the electronic shell of oxygen ions in silicates containing only cations of noble gas type is compared on the basis of the apparent Lorentz‐Lorenz molar refraction per one O2‐. These values are derived from the molar refraction of the silicate by subtracting those of Si4+ and of the other cations in the free gaseous state. It is shown that the electronic shell of the oxygen ions becomes less tight in the series 2Be2+, Si4+, 4/3Al3+, 2Mg2+, 4Li+, etc., which is that of decreasing field strength of the cation. Increase of the ratio of the numbers of O to Si atoms also leads to decreased tightness.
SUPEROPAQUE ENAMELS OF LOW SiO2 CONTENT*
Authors: Baldwin W. J. 
Published: June 2006

AbstractA series of enamel compositions are described which differ radically from the present antimony‐ or zirconium‐opacified types of superopaque enamels. The method for deriving formulations is shown. Basically the compositions are an alumina phosphate type of glass. The ratio of SiO: A12O3: P2O6 is of extreme importance not only in obtaining maximum reflectance values, but also in determining the color of the fired enamel. Titanium oxide is desirable for developing opacity in this type of composition and the amount required is, to a large extent, dependent upon the SiO2: Al2Os: P2O3 ratio. Compositions are given, containing only 5% melted weight of TiO2. These enamels give reflectance values of 80 to 85% at application weights of 40 gm. per sq. ft.
PROPERTIES OF BARIUM‐MAGNESIUM TITANATE DIELECTRICS*
Authors: Shelton Gborge R. , Creamer Ansel S. , Bunting Elmer N. 
Published: June 2006

AbstractDielectrics having compositions in the system BaTiO3‐‐4MgO:TiO2‐TiO2 were matured (<0.1% of absorption) at temperatures from 1275° to 1425°C. Data are given for dielectric constant, K, and the reciprocal of the power factor, Q, at 25°C. and frequencies of 50, 1000, 20,000 kc. per sec. and 3000 me. per sec.; also K at a frequency of 1 mc. per sec. and at various temperatures from —60° to 85°C. Values of K (1 mc. per sec. and 25°C.) ranged from 12 to 1550 and those of Q from 9 to 10,000. Values of K decreased and those of Q increased for several weeks after specimens were matured, when the content of BaO was greater than 30% and that of TiO2 less than 50%. Partial restoration of the original values of K and Q resulted from Beating these specimens at various temperatures for brief periods. Linear thermal expansion (25° to 700°C.) ranged from 0.46 to 0.71%. A few specimens of barium‐strontium titan ate were tested for the effects of thermal history on the properties.
FUNDAMENTAL STUDY OF CLAY: VIII, A NEW THEORY FOR THE PLASTICITY OF CLAY‐WATER MASSES*
Authors: Norton F. H. 
Published: June 2006

AbstractIn spite of the large amount of work which has been done in the field of plasticity, none of the explanations are entirely fitted to the facts when dealing with clay‐water systems of pasty consistency. As there is now a considerable amount of data on carefully fractionated and cleaned kaolinite, it has been possible to substantiate a new mechanism of plasticity which is termed the “stretched‐membrane theory.” This theory accounts for the plasticity of the clay masses by the compression of the whole due to the surface envelope of water which tends to push the particles together by capillary forces. This theory is shown to be reasonable by both direct and indirect proof; however, it in no way changes the general picture of the forces acting between the particles in a suspension as portrayed by the colloid chemists.1,2
Determination of Strains in Enameled Cast Iron
Authors: WUELLNER J. F. , SWEO B. J. 
Published: June 2006

A method of determining strains in enameled cast iron using a modification of the split‐ring furnace and employing cantilever‐type specimens is described. Strain curves of several cast‐iron enamels on cast‐iron cantilever‐type specimens are compared with results obtained on split rings. Strain curves are presented which show that cast‐iron enamels may craze at or close to the temperature of maximum tension of the enamels owing to the high degree of tensile strain in the enamels. This maximum tension can be increased by permanent growth of the cast iron.SummaryThe cast‐iron strip test as modified from the split‐ring test for sheet steel enamels serves as a more direct means of determining the strain existing between enamel and cast‐iron from room temperature to the softening point of the enamel. The cast‐iron strip test shows differences in cast iron enamels that have not been indicated by either the warp or split‐ring tests.Cast‐iron enamels may craze at or close to the temperature of maximum tension, and this crazing is caused by the enamel being subjected to too high a degree of tensile stress during cooling. The degree of tensile strain is increased by the growth of iron which occurs if the temperature is held within, or moves too slowly through, the range of maximum tension of the enamel. By controlling the cooling rate, the strains in enameled cast iron can be altered.
Fracture Properties of Polycrystalline Lithia‐Stabilized β“‐ Alumina
Authors: VIRKAR ANIL V. , GORDON RONALD S. 
Published: June 2006

The critical stress‐intensity factor, K1C, and the fracture strength, σf, have been investigated on both hot‐pressed and sintered lithia‐stabilized β”‐alumina. The hot‐pressed material possessed a strong preferred orientation with many of the basal planes aligned perpendicular to the direction of hot‐pressing. Both K1C and σf were found to be orientation‐dependent. Two regimes of fracture were identified. In fine‐grained material (<120 μm), the strength was slightly dependent on grain size.For larger grain sizes, the strength decreased rapidly with increasing grain size and the fracture mode was almost entirely transgranular. The K1C values for sintered β”‐alumina were in the same range as those obtained on the hot‐pressed material.
Reaction of Clay and Carbon to Form and Separate Al2O3 and SiC
Authors: BECHTOLD BRYANT C. , CUTLER IVAN B. 
Published: June 2006

Alumina and SiC can be recovered from clay by carbon reduction. Kinetic experiments showed that the solid‐solid reaction proceeds through gaseous intermediates of CO and SiO. By mixing part of the carbon with the clay and using the balance to form SiC, Al2O3 and SiC were physically separated as products. This separation is represented by

image

image
Optimum conditions for ease of separation of Al2O3 and SiC and the high rate of reaction require pelletization of both the clay‐carbon mixture and the carbon of reaction (b) and the reaction of these pellets at >1500°C. By examining the effect of transition metal catalysts, SiC formation was determined to be rate‐controlling.
Analysis of Thermal Stress Failure of Segmented Thick‐Walled Refractory Structures
Authors: CHANG W. S. , KNIGHT C. E. , HASSELMAN D. P. H. , MITCHINER R. G. 
Published: June 2006

A finite‐element analysis was conducted of the thermal stresses in rectangularly shaped components of segmented thick‐walled refractory structures with length in the direction of heat flow much larger than the height or width. Heating was assumed to occur uniformly at a linear rate over the front face defined by the smaller dimensions. Most calculations were carried out for two‐dimensional conditions of plane stress, which assumes that the magnitude of stress is independent of height. A limited number of three‐dimensional calculations permitted analyzing the effect of height. For moderate values of heating rates, corresponding to those possibly encountered in practice, a biaxial tensile stress was found to exist some distance behind the hot face with the maximum value of stress along the center‐line parallel to the component length, in accordance with the fracture mode observed in practice. At high heating rates, however, the maximum tensile stress component was found to occur parallel to the face being heated.For conditions of plane stress under moderate heating rates, the magnitude of stress was found to be proportional to heating rate and an inverse function of the thermal diffusivity. Maximum values of stress were encountered for intermediate values of width. This latter result suggests that the incidence of thermal stress failure may be reduced by either reductions or increases in the values of width commonly used in practice. The three‐dimensional calculations indicated that the magnitude of stress rises rapidly with height. This result suggests that improvements in thermal stress resistance can be obtained by reductions in the values of height from the current values in practice. By means of a fracture‐mechanical analysis it is demonstrated that cracks oriented perpendicularly to the direction of heat flow formed as the result of the above stresses could be unstable and are expected to propagate across the total cross section to lead to total separation, in accordance with observations. The stress values obtained in the present study were compared with those predicted by the Kienow theory. Reasonable agreement was found for the peak stresses at the lower values of time. However, with increasing duration and the higher values of height the Kienow theory underestimates the magnitude of stress considerably.
The dynamics of injection drug users’ personal networks and HIV risk behaviors
Authors: Costenbader Elizabeth C. , Astone Nan M. , Latkin Carl A. 
Published: June 2006

ABSTRACTAims  While studies of the social networks of injection drug users (IDUs) have provided insight into how the structures of interpersonal relationships among IDUs affect HIV risk behaviors, the majority of these studies have been cross‐sectional. The present study examined the dynamics of IDUs’ social networks and HIV risk behaviors over time.Design  Using data from a longitudinal HIV‐intervention study conducted in Baltimore, MD, this study assessed changes in the composition of the personal networks of 409 IDUs. We used a multi‐nomial logistic regression analysis to assess the association between changes in network composition and simultaneous changes in levels of injection HIV risk behaviors. Using the regression parameters generated by the multi‐nomial model, we estimated the predicted probability of being in each of four HIV risk behavior change groups.Findings  Compared to the base case, individuals who reported an entirely new set of drug‐using network contacts at follow‐up were more than three times as likely to be in the increasing risk group. In contrast, reporting all new non‐drug‐using contacts at follow‐up increased the likelihood of being in the stable low‐risk group by almost 50% and decreased the probability of being in the consistently high‐risk group by more than 70%.Conclusions  The findings from this study show that, over and above IDUs’ baseline characteristics, changes in their personal networks are associated with changes in individuals’ risky injection behaviors. They also suggest that interventions aimed at reducing HIV risk among IDUs might benefit from increasing IDUs’ social contacts with individuals who are not drug users.
Near East mtDNA haplotype variants in Roman cattle from Augusta Raurica, Switzerland, and in the Swiss Evolène breed
Authors: Schlumbaum A. , Turgay M. , Schibler J. 
Published: June 2006

SummaryTypical Near East mitochondrial haplotypes of the T2 lineage were found in one cattle metacarpus sample from the Roman period and in two present‐day Evolène cattle in Switzerland. Sequences from eight additional Evolène and four Raetian Grey aligned to the European haplotype T3. Analysis of nucleotide diversity within the mitochondrial D‐loop of both studied Swiss cattle breeds revealed high haplotype diversity and similar diversity to a European cattle reference group. Mitochondrial T3 haplotypes radiated star‐like from two similarly frequent haplotypes, possibly indicating two different expansion routes. The breed structure of Evolène cattle can be explained either by an introduction of diverse female lineages from the domestication centre or by later admixture. The introduction of the Near East lineage to Switzerland must have happened during the Roman time or earlier.
Cross‐species overgo hybridization and comparative physical mapping within avian genomes
Authors: Romanov M. N. , Dodgson J. B. 
Published: June 2006

SummaryThe chicken genome sequence facilitates comparative genomics within other avian species. We performed cross‐species hybridizations using overgo probes designed from chicken genomic and zebra finch expressed sequence tags (ESTs) to turkey and zebra finch BAC libraries. As a result, 3772 turkey BACs were assigned to 336 markers or genes, and 1662 zebra finch BACs were assigned to 164 genes. As expected, cross‐hybridization was more successful with overgos within coding sequences than within untranslated region, intron or flanking sequences and between chicken and turkey, when compared with chicken‐zebra finch or zebra finch‐turkey cross‐hybridization. These data contribute to the comparative alignment of avian genome maps using a ‘one sequence, multiple genomes’ strategy.
Evolution of the late Cenozoic Chaco foreland basin, Southern Bolivia
Authors: Uba Cornelius Eji , Heubeck Christoph , Hulka Carola 
Published: June 2006

ABSTRACTEastward Andean orogenic growth since the late Oligocene led to variable crustal loading, flexural subsidence and foreland basin sedimentation in the Chaco basin. To understand the interaction between Andean tectonics and contemporaneous foreland development, we analyse stratigraphic, sedimentologic and seismic data from the Subandean Belt and the Chaco Basin. The structural features provide a mechanism for transferring zones of deposition, subsidence and uplift. These can be reconstructed based on regional distribution of clastic sequences. Isopach maps, combined with sedimentary architecture analysis, establish systematic thickness variations, facies changes and depositional styles. The foreland basin consists of five stratigraphic successions controlled by Andean orogenic episodes and climate: (1) the foreland basin sequence commences between ∼27 and 14 Ma with the regionally unconformable, thin, easterly sourced fluvial Petaca strata. It represents a significant time interval of low sediment accumulation in a forebulge‐backbulge depocentre. (2) The overlying ∼14–7 Ma‐old Yecua Formation, deposited in marine, fluvial and lacustrine settings, represents increased subsidence rates from thrust‐belt loading outpacing sedimentation rates. It marks the onset of active deformation and the underfilled stage of the foreland basin in a distal foredeep. (3) The overlying ∼7–6 Ma‐old, westerly sourced Tariquia Formation indicates a relatively high accommodation and sediment supply concomitant with the onset of deposition of Andean‐derived sediment in the medial‐foredeep depocentre on a distal fluvial megafan. Progradation of syntectonic, wedge‐shaped, westerly sourced, thickening‐ and coarsening‐upward clastics of the (4) ∼6–2.1 Ma‐old Guandacay and (5) ∼2.1 Ma‐to‐Recent Emborozú Formations represent the propagation of the deformation front in the present Subandean Zone, thereby indicating selective trapping of coarse sediments in the proximal foredeep and wedge‐top depocentres, respectively.Overall, the late Cenozoic stratigraphic intervals record the easterly propagation of the deformation front and foreland depocentre in response to loading and flexure by the growing Intra‐ and Subandean fold‐and‐thrust belt.
Racial and socioeconomic disparity in perforated appendicitis among children: where is the problem?
Authors: Jacobson Robert M. 
Published: June 2006

Nwomeh B.C.,
Chisolm D.J.,
Caniano D.A. &
Kelleher K.J.
(
2006
)

,
117
,
870
–
875
.
Objective  Significant racial, ethnic and socio‐economic disparities have been observed in the rates of perforated appendicitis among children, by using large administrative databases. This study evaluated whether these factors had an impact on the care of patients with appendicitis at a major children’s hospital in the USA with a well‐established, comprehensive and primary referral system.Methods  A retrospective analysis was performed for all children between the ages of 2 and 20 years old who were treated for appendicitis between 1 January 2001 and 31 December 2003. Demographic variables included patient age, gender, race, insurance status, parental educational status and income level. Coding data were used to identify patients with perforated appendicitis. The use of radiologic imaging was also analysed.Results  During the 3‐year period, 788 patients were treated for appendicitis. The racial distribution (white: 81%; black: 12%; other: 7%) was consistent with the demographic composition of the local population. The overall perforation rate was 25%, and the rate was significantly greater in the age group of <6 years, compared with older children. However, there were no significant differences in the perforation rate with respect to race, insurance status, educational level, or income status. Rates of radiologic imaging use were similar among all racial and socio‐economic groups.Conclusions  Although racial and socio‐economic disparities in the rates of perforated appendicitis among children have been reported, we found no significant evidence for such inequality at our institution. This may reflect improved access, early diagnosis and referral by primary care physicians in the community. Pooled national and multiple‐state administrative databases have been used to highlight persistent disparities in health care. This study illustrates how single‐institution data sources can be used to test a local hypothesis generated by national data, with surprisingly different results.
Treatment with chitin microparticles is protective against lung histopathology in a murine asthma model
Authors: Ozdemir C. , Yazi D. , Aydogan M. , Akkoc T. , Bahceciler N. N. , Strong P. , Barlan I. B. 
Published: June 2006

SummaryBackground
Chitin, a natural polysaccharide extracted from shrimp, is a potent T and B cell adjuvant when delivered in the form of chitin microparticles and can shift a polarized T‐helper type 2 (Th2) immune response towards a Th1 response.Objective
We investigated the beneficial effects of the intranasal application of chitin microparticles in newborn mice before and after the establishment of a model of allergic asthma.Methods
Mice were grouped as asthma (A), primary prevention (PP), treatment (T), primary prevention+treatment (PPT) and control (C) groups. All mice except controls were sensitized with ovalbumin intraperitoneally and challenged intratracheally to establish the asthma model. Mice in the PP and PPT groups received chitin microparticles intranasally during the newborn period before sensitization. Mice in the PPT and T groups received intranasal chitin microparticles after challenge. Airway histopathology was evaluated in all groups.Results
All of the airway histopathologic parameters of small and medium‐sized airways of the T and PPT groups were significantly ameliorated when compared with the asthma model group. In the large airways, thicknesses of basement membrane, epithelium and subepithelial smooth muscle layers of the PPT group and basement membrane thicknesses of the T group were also significantly lower compared with the asthma model group. Comparison of the PP group with the asthma model group revealed significantly reduced goblet cell numbers and significantly reduced epithelial and basement membrane thicknesses in small and medium airways, in addition to significantly reduced basement membrane thicknesses in the medium‐sized airways.Conclusion
Intranasal application of microgram quantities of chitin microparticles had a beneficial effect in preventing and treating histopathologic changes in the airways of asthmatic mice.
In silico identification of potential new latex allergens
Authors: Guarneri F. , Guarneri C. , Guarneri B. , Benvenga S. 
Published: June 2006

SummaryBackground
Allergy to latex of Hevea brasiliensis is a frequent problem. In spite of the significant progress of research, the identity and cross‐reactivity of some latex allergens are unknown.Objective
To identify, among the fully characterized latex proteins, those with a higher probability to be allergenic.Methods
We used in silico techniques (amino acid sequence comparison and molecular modelling) to identify potential new allergens among the known proteins of H. brasiliensis.Results
Cu/Zn superoxide dismutase, heat shock protein and calmodulin of H. brasiliensis show highly significant (E<10−9) amino acid sequence homologies with known allergens.Conclusions
On the basis of our data, Cu/Zn superoxide dismutase, heat shock protein and calmodulin are the most probable allergens among fully characterized proteins of H. brasiliensis, and could potentially explain, at least in part, the multiple cross‐reactivities of latex with vegetable foods and other plant‐derived products. Consequently, we think that the above proteins should be particularly considered in the future laboratory and clinical research.