Dielectric behaviour of glasses and glass ceramics in the system BaO-PbO-TiO2-B2O3-SiO2

Glasses with varying molar ratios of PbO/BaO in the system BaO-PbO-TiO₂-B₂O₃-SiO₂ were prepared keeping (BaO + PbO)/TiO₂ ratio equal to one. The glasses were ceramized by two-stage heat treatment. X-ray diffraction indicates that PbTiO₃ crystallizes in lead-rich glasses while BaTiO₃ precipitates in barium-rich compositions. Solid solution (Ba, Pb)TiO₃ does not seem to crystallize over the entire range of compositions. Simultaneous presence of PbO and BaO in the initial glass composition reduces the yield of ferroelectric phase. Dielectric properties have been interpreted in terms of microstructural features.     

Ultrasonographically-guided fine-needle aspiration cytology in the diagnosis of colonic lesions

BACKGROUND: The use of fine-needle aspiration cytology (FNAC) in the diagnosis of colonic lesions was investigated. METHODS: Some 22 patients (median age 71 years) with a colonic lesion identified on abdominal ultrasonography underwent ultrasonographically-guided FNAC using a 21-G needle. The sample was checked immediately by a cytopathologist for adequacy. RESULTS: Eighteen patients had colonic carcinoma; aspiration cytology detected malignant epithelial cells consistent with colonic carcinoma in 17 patients and severely dysplastic cells in one patient. The sensitivity and specificity of ultrasonographically-guided FNAC in the diagnosis of colonic carcinoma was 94 and 100 per cent respectively. The remaining four patients had a diagnosis of ileocaecal tuberculosis, ileocaecal Crohn's disease, and metastatic adenocarcinoma in the liver with no identifiable primary (two patients). One demonstrated granulomata, grew acid-fast bacilli and the patient was treated for tuberculosis. One had inflammatory cells and the patient was found to have Crohn's disease on histology. The remaining two patients had confirmed metastatic adenocarcinoma in the liver on aspiration cytology but suspected colonic lesions were found to be benign on cytological examination and no primary lesion was subsequently demonstrated. There were no complications of FNAC and patients complained of minimal discomfort. There has been no evidence of tumour recurrence with a median follow-up of 12 (range 1-25) months. CONCLUSION: Ultrasonographically-guided FNAC is a valid method for the diagnosis of colonic tumours.     

A simple correlation for estimating viscosities of solutions of salts in aqueous,non-aqueous and mixed solvents applicable to high concentration,temperature and pressure

A new correlation is proposed to correlate the viscosities of salt solutions in aqueous, non-aqueous solvents and their mixtures. The correlation involves two parameters i.e. solvation number and ion-solvent interaction coefficient, which are well-documented quantities in the literature. The proposed correlation has been examined on the experimental viscosity data of salt solutions in aqueous, non-aqueous and their mixtures up to 473 K and 31 MPa pressure. The salts with various ionic charges were employed for testing the proposed correlation. Several non-aqueous solvents like dimethyl sulphoxide, alcohols and formamide were included for the data regression. The viscosities of these solutions can be correlated to within 0.7%.     

Geometrical and sequence characteristics of alpha-helices in globular proteins

Understanding the sequence-structure relationships in globular proteins is important for reliable protein structure prediction and de novo design. Using a database of 1131 alpha-helices with nonidentical sequences from 205 nonhomologous globular protein chains, we have analyzed structural and sequence characteristics of alpha-helices. We find that geometries of more than 99% of all the alpha-helices can be simply characterised as being linear, curved, or kinked. Only a small number of alpha-helices ( approximately 4%) show sharp localized bends in their middle regions, and thus are classified as kinked. Approximately three-fourths (approximately 73%) of the alpha-helices in globular proteins show varying degrees of smooth curvature, with a mean radius of curvature of 65 +/- 33 A; longer helices are less curved. Computation of helix accessibility to the solvent indicates that nearly two-thirds of the helices ( approximately 66%) are largely buried in the protein core, and the length and geometry of the helices are not correlated with their location in the protein globule. However, the amino acid compositions and propensities of individual amino acids to occur in alpha-helices vary with their location in the protein globule, their geometries, and their lengths. In particular, Gln, Glu, Lys, and Arg are found more often in helices near the surface of globular proteins. Interestingly, kinks often seem to occur in regions where amino acids with low helix propensities (e.g., beta-branched and aromatic residues) cluster together, in addition to those associated with the occurrence of proline residues. Hence the propensities of individual amino acids to occur in a given secondary structure depend not only on conformation but also on its length, geometry, and location in the protein globule.     

Variation of wave impedance of shielded suspended dielectric guide

A shielded suspended dielectric guide is a dielectric rectangular slab enclosed by regular metallic side walls from all the sides. This type of structure is used in dual mode phase shifter where the size of the normal rectangular wave guide is reduced at the ends, where a dielectric material is embeded in ferrite core. Hence impedance variation of a phase shifter at its transition may be easily calculated using shielded suspended dielectric guide which is a prime parameter for optimum efficiency of wave launching.     

Establishment of human parotid pleomorphic adenoma cells in culture: morphological and biochemical characterization

This study reports the establishment of alpha-amylase-producing human parotid pleomorphic adenoma cell lines (2HP and 2HP1) which have been maintained in culture for over 1 yr. The procedures required preparation of cellular clumps from tumor tissue and plating them on plasma clot or precoated dishes. During the initial phase of growth they required modified MCDB-153 medium without serum. When cells showed signs of degeneration they were changed to MCDB-153 medium containing first 2% and then 10% heat inactivated fetal bovine serum. Although cells grew well in MCDB-153 containing 10% serum, the epithelial cell morphology was not distinct. Therefore, the growth and morphology of cells grown in MCDB-10% serum were compared with those in RPMI growth medium containing 10% fetal bovine serum and F12 containing 10% agammaglobulin newborn bovine serum. Although the growth of cells was a little slower in F12 medium than those in MCDB and RPMI, the epithelial cell morphology was maintained better than in other growth media. The cells of 2HP and 2HP1 produce low levels of alpha-amylase and relatively high levels of alpha-amylase mRNAs of 1176 and 702 bp and contain neurofilament-160, a neuronal-specific marker. The cells of 2HP1 are tumorigenic when tested in athymic mice, but the cells of 2HP are not. The establishment of amylase-producing human parotid adenoma cell lines of different characteristics in culture provides a new opportunity to study the mechanisms of differentiation and transformation, and regulation of alpha-amylase in these cells.     

Differential proteomics of human seminal plasma: A potential target for searching male infertility marker proteins

The clinical fertility tests, available in the market, fail to define the exact cause of male infertility in almost half of the cases and point toward a crucial need of developing better ways of infertility investigations. The protein biomarkers may help us toward better understanding of unknown cases of male infertility that, in turn, can guide us to find better therapeutic solutions. Many clinical attempts have been made to identify biomarkers of male infertility in sperm proteome but only few studies have targeted seminal plasma. Human seminal plasma is a rich source of proteins that are essentially required for development of sperm and successful fertilization. This viewpoint article highlights the importance of human seminal plasma proteome in reproductive physiology and suggests that differential proteomics integrated with functional analysis may help us in searching potential biomarkers of male infertility.     

Hierarchical Fuzzy Systems Integrated with Particle Swarm Optimization for Daily Reference Evapotranspiration Prediction: a Novel Approach

Water Resources Management - Reference evapotranspiration (ET0) is a crucial element for deriving irrigation scheduling of major crops. Thus, precise projection of ET0 is essential for better...     

Dielectric behaviour of hot pressed AlN ceramic exposed to inorganic acid vapours

Dielectric behaviour of hot pressed AIN ceramic is studied before and after exposing the samples to inorganic acid (HCl and HNO₃) vapours with a specific aim to study the effect of these vapours on the dielectric constant () and dissipation factor (tan ). Four samples having different volume percentage of porosity (0.2 to 15%) are selected for this study. Dielectric dispersion increases after exposing the samples to the above acid vapours. Tan also increases quite appreciably; the increase being more at higher porosity. Recovery studies show that the exposure effect is reversible. The exposure time dependence of and tan indicates that these parameters show a maxima at a particular exposure time. However, no such maxima is observed in the gravimetric measurements. The increase in dielectric parameters after exposure to acid vapours is explained in terms of the ionic conduction due to the dissociation of these vapours in the presence of moisture. The porosity dependence of this effect is discussed in terms of closed and open porosity reported by other workers.