Different Constituents (different + constituent)

Distribution by Scientific Domains


Selected Abstracts


Work-hardening characteristics of Zn-Ti alloy single crystals

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 2 2010
G. Boczkal
Abstract Shear stress , shear strain curves of 0.14 at.%Ti alloyed Zn single crystals were measured in compression at different temperatures and shear strain rates. The work-hardening coefficient for basal slip increases with decreasing temperature and increasing shear strain rate. The work-hardening characteristics are compared with those reported for Zn single crystals with different constituents and purities. It is discussed with respect to the interaction of dislocations with dislocations, vacancies, vacancy agglomerates and solute atoms. ( 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Intrinsic aging vs. photoaging: a comparative histopathological, immunohistochemical, and ultrastructural study of skin

EXPERIMENTAL DERMATOLOGY, Issue 5 2002
M. El-Domyati
Abstract: Cutaneous aging is a complex biological phenomenon affecting the different constituents of the skin. To compare the effects of intrinsic and extrinsic aging processes, a total of 83 biopsies were collected from sun-exposed and protected skin of healthy volunteers representing decades from the 1st to the 9th (6,84 years of age). Routine histopathology coupled with computer-assisted image analysis was used to assess epidermal changes. Immunoperoxidase techniques with antibodies against type I and type III collagens and elastin were used to quantitatively evaluate changes in collagen and elastic fibers and their ultrastructure was examined by transmission electron microscopy. Epidermal thickness was found to be constant in different decades in both sun-exposed and protected skin; however, it was significantly greater in sun-exposed skin (P = 0.0001). In protected skin, type I and III collagen staining was altered only after the 8th decade, while in sun-exposed skin the relative staining intensity significantly decreased from 82.5% and 80.4% in the 1st decade to 53.2% and 44.1% in the 9th decade, respectively (P = 0.0004 and 0.0008). In facial skin the collagen fiber architecture appeared disorganized after the 4th decade. The staining intensity of elastin in protected skin significantly decreased from 49.2% in the 1st decade to 30.4% in the 9th decade (P = 0.05), whereas in sun-exposed skin the intensity gradually increased from 56.5% in the 1st decade to 75.2% in the 9th decade (P = 0.001). The accumulated elastin in facial skin was morphologically abnormal and appeared to occupy the areas of lost collagen. Collectively, the aging processes, whether intrinsic or extrinsic, have both quantitative and qualitative effects on collagen and elastic fibers in the skin. [source]


Contribution to X-ray analysis of carbo-nitrided steel layers

JOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 5 2001
J. M. Sprauel
The non-destructive X-ray diffraction method is used to analyse carbo-nitrided steel layers after wear testing. These measurements are carried out on the two major phases of the material, i.e. the martensite and the retained austenite. Such measurements are particularly difficult for three reasons. First, strong gradients exist across the wear track. Second, the diffraction peaks obtained for the martensite are broadened, as a result of the overlap of different reflections of the tetragonal structure. Third, the studied material is multiphase. Its major phases are martensite and austenite, but it also contains carbide and nitride clusters, which lead to incoherent scattering of X-rays. A new quantitative phase analysis method is thus proposed to define the volume fractions of these different constituents of the material. This method accounts for the evolution of the background level during wear. A micro-mechanical model is then developed to process the diffraction peak positions obtained for the martensite and the retained austenite. This model defines the `true' stress and carbon content of both phases. It also allows separation of the reflections of the martensite. The true widths of the diffraction peaks, which characterize the plastic deformation, can thus be quantified. Results for wear-test specimens show a strong plastic deformation of the retained austenite during contact fatigue. This leads to a partial transformation of this phase into martensite. In the martensite, on the contrary, the plastic deformation remains low but the carbon content decreases. This is caused by a stress-induced precipitation of carbides. [source]


Use of mid-infrared spectroscopy in the diffuse-reflectance mode for the prediction of the composition of organic matter in soil and litter

JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 3 2008
Bernard Ludwig
Abstract Mid-infrared spectroscopy (MIRS) is assumed to be superior to near-infrared spectroscopy (NIRS) for the prediction of soil constituents, but its usefulness is still not sufficiently explored. The objective of this study was to evaluate the ability of MIRS to predict the chemical and biological properties of organic matter in soils and litter. Reflectance spectra of the mid-infrared region including part of the near-infrared region (7000,400,cm,1) were recorded for 56 soil and litter samples from agricultural and forest sites. Spectra were used to predict general and biological characteristics of the samples as well as the C composition which was measured by 13C CPMAS-NMR spectroscopy. A partial least-square method and cross-validation were used to develop equations for the different constituents over selected spectra ranges after several mathematical treatments of the spectra. Mid-infrared spectroscopy predicted well the C : N ratio: the modeling efficiency EF was 0.95, the regression coefficient (a) of a linear regression (measured against predicted values) was 1.0, and the correlation coefficient (r) was 0.98. Satisfactorily (EF , 0.70, 0.8 , a , 1.2, r , 0.80) assessed were the contents of C, N, and lignin, the production of dissolved organic carbon, and the contents of carbonyl C, aromatic C, O-alkyl C, and alkyl C. However, the N mineralization rate, the microbial biomass and the alkyl,to,aromatic C ratio were predicted less satisfactorily (EF < 0.70). Limiting the sample set to mineral soils did generally not result in improved predictions. The good and satisfactory predictions reported above indicate a marked usefulness of MIRS in the assessment of chemical characteristics of soils and litter, but the accuracies of the MIRS predictions in the diffuse-reflectance mode were generally not superior to those of NIRS. [source]


Near-infrared spectroscopy can predict the composition of organic matter in soil and litter

JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 2 2006
Thomas Terhoeven-Urselmans
Abstract The usefulness and limitations of near-infrared reflectance spectroscopy (NIRS) for the assessment of several soil characteristics are still not sufficiently explored. The objective of this study was to evaluate the ability of visible and near-infrared reflectance (VIS-NIR) spectroscopy to predict the composition of organic matter in soils and litter. Reflectance spectra of the VIS-NIR region (400,2500 nm) were recorded for 56 soil and litter samples from agricultural and forest sites. Spectra were used to predict general and biological characteristics of the samples as well as the C composition which was measured by 13C-CPMAS-NMR spectroscopy. A modified partial least-square method and cross-validation were used to develop equations for the different constituents over the whole spectrum (1st to 3rd derivation). Near-infrared spectroscopy predicted well the C : N ratios, the percentages of O-alkyl C and alkyl C, the ratio of alkyl C to O-alkyl C, and the sum of phenolic oxidation products: the ratios of standard deviation of the laboratory results to standard error of cross-validation (RSC) were greater than 2, the regression coefficients (a) of a linear regression (measured against predicted values) ranged from 0.9 to 1.1, and the correlation coefficients (r) were greater than 0.9. Satisfactorily (0.8 , a , 1.2, r , 0.8, and 1.4 , RSC , 2.0) assessed were the contents of C, N, and production of DOC, the percentages of carbonyl C and aromatic C and the ratio of alkyl C to aromatic C. However, the N-mineralization rate and the microbial biomass were predicted unsatisfactorily (RSC < 1.4). The good and satisfactory predictions reported above indicate a marked usefulness of NIRS in the assessment of biological and chemical characteristics of soils and litter. [source]


Internal governance in the community college: Models and quilts

NEW DIRECTIONS FOR COMMUNITY COLLEGES, Issue 141 2008
Michael T. Miller
This chapter describes the various approaches to internal shared governance utilized by community colleges, ranging from approaches that intentionally involve different constituents to those evolved from habit, tradition, and precedence. [source]


Effect of the alcoholic extract of Ashwagandha leaves and its components on proliferation, migration, and differentiation of glioblastoma cells: Combinational approach for enhanced differentiation

CANCER SCIENCE, Issue 9 2009
Navjot Shah
Ashwagandha (Withania somnifera) is widely used in the Indian traditional system of medicine, Ayurveda. Although it is claimed to have a large variety of health-promoting effects, including therapeutic effects on stress and disease, the mechanisms of action have not yet been determined. In the present study, we aimed to investigate the growth inhibition and differentiation potential of the alcoholic extract of Ashwagandha leaves (i-Extract), its different constituents (Withaferin A, Withanone, Withanolide A) and their combinations on glioma (C6 and YKG1) cell lines. Withaferin A, Withanone, Withanolide A and i-Extract markedly inhibited the proliferation of glioma cells in a dose-dependent manner and changed their morphology toward the astrocytic type. Molecular analysis revealed that the i-Extract and some of its components caused enhanced expression of glial fibrillary acidic protein, change in the immunostaining pattern of mortalin from perinuclear to pancytoplasmic, delay in cell migration, and increased expression of neuronal cell adhesion molecules. The data suggest that the i-Extract and its components have the potential to induce senescence-like growth arrest and differentiation in glioma cells. These assays led us to formulate a unique combination formula of i-Extract components that caused enhanced differentiation of glial cells. (Cancer Sci 2009; 100: 1740,1747) [source]