X-ray photoelectron spectrum, X-ray diffraction data, and electronic structure of chalcogenide quaternary sulfide Ag2In2GeS6: experiment and theory

We report measurements of the X-ray diffraction and X-ray photoelectron spectrum on single crystals of Ag₂In₂GeS₆. We also present first principles calculations of the band structure and density of states using the state-of-the-art full potential augmented plane wave method with different possible approximation for the exchange correlation potential. In this paper, we make a detailed comparison of the density of states deduced from the X-ray photoelectron spectra with our calculations. The theoretical results of the density of states are in reasonable agreement with the X-ray photoelectron spectroscopy (VB-XPS) measurements with respect to peak positions. The calculated density of states shows there is a strong hybridization between the states in the valence and conduction bands states. We have calculated the electron charge density distribution in the (100) and (110) planes. In the plane (100), there exists Ag, In, and S atoms, while the plane (110) Ag, S, and Ge atoms are present. The bonding properties are obtained from the charge density distributions. The calculation show that there is partial ionic and strong covalent bonding between Ag–S, In–S, and Ge–S atoms depending on Pauling electro-negativity difference of S (2.58), Ge (2.01), Ag (1.93), and In (31.78) atoms.     

Structural and optical properties of novel optoelectronic Tl1−xIn1−xSixSe2 single crystals

Principal optical properties of Tl_1?xIn_1?xSi_xSe₂ solid state crystalline alloys were studied. The influence of the x on the principal optical and structural features was explored. Temperature features of the band energy gap are studied. The possible explanation of the observed behavior is given within a framework of the Urbach rule approach. The role of intrinsic defective sub-system and anharmonic electron–phonon interaction is discussed. A possible application of the titled materials for the infrared optoelectronic is discussed. The replacement of In atoms by Sn is evaluated. Additionally studies of influence of x on the optoelectronic features is done. The formation of the positive charged ions (donors) and negatively charged ions is explored within the introduced intrinsic defect models.     

Coherent and incoherent components of a synchrotron radiation spot produced by separate capillaries

We discuss soft-x-ray focusing properties of separate capillaries. It is shown that a nonnegligible fraction of the synchrotron radiation beam transmitted by the capillary is modal. Experimental and theoretical data are discussed to explain the superposition pattern of x rays in the focal plane due to the interference phenomena of electromagnetic radiation propagating through separate capillaries.     

Extension of the thermodynamics of small systems to open metastable states: an example

By using a simplified model of small open liquid-like clusters with surface effects, in the gas phase, it is shown how the statistical thermodynamics of small systems can be extended to include metastable supersaturated gaseous states not too far from the gas-liquid equilibrium transition point. To accomplish this, one has to distinguish between mathematical divergence and physical convergence of the open-system partition function.     

Adenoviral-mediated transfer of a heat-inducible double suicide gene into prostate carcinoma cells

Tumor cells that express a fusion gene comprised of Escherichia coli cytosine deaminase (CD) and herpes simplex virus type 1 thymidine kinase (TK) sequences exhibit activation of and subsequent killing by the normally innocuous prodrugs 5-fluorocytosine and ganciclovir (Rogulski et al., Hum. Gene Ther., 8: 73-85, 1997). To target localized expression of this therapeutic gene, we have constructed a recombinant adenovirus containing the CD-TK fusion gene under the control of a human inducible heat shock protein 70 promotional sequence. Strong expression of the fusion gene product was induced by heating at 41 degrees C for 1 h. Expression levels obtained were dependent on the multiplicity of infection used and the incubation time after heat shock. Heat-induced expression of the CD-TK protein significantly reduced the survival of PC-3 cells in the presence of both 5-fluorocytosine and ganciclovir. These studies represent a novel form of gene therapy for the transduction and regulation of a double suicide gene in tumor cells and may provide a unique application for hyperthermia in cancer therapy.     

Hypothalamic synaptogenesis and its relationship with the maturation of hormonal secretion

1. Information obtained during the last decade has demonstrated that hypothalamic neurons release a wide variety of neuroactive substances, such as neurotransmitters, mostly monoamines and amino acids, and neuromodulators such as the peptides vasopressin (AVP) and oxytocin (OXT) and hypophysial releasing hormones. 2. Synapse formation between hypothalamic neurons was followed at different times within a given nucleus and among different nuclei during development of the mouse hypothalamus. 3. The amounts of various neurotransmitters and hormones were determined at various stages of development. 4. A correlation is presented of the biochemical and ultrastructural features and their functional implications during maturation.     

The female athlete. The triad of disordered eating, amenorrhoea and osteoporosis

The value of routine follow-up programs for patients with early stage breast cancer remains an area of controversy. In recent years, the cost-effectiveness of routine investigations has been questioned, and 2 prospective randomized clinical trials have shown no survival advantage to more intensive diagnostic follow-up approaches. Under the auspices of the Ottawa Regional Cancer Centre, a national survey of the practice patterns of Canadian surgical, radiation and medical oncologists was undertaken to measure current Canadian standards of care and to determine average costs of 5-year follow-up for patients completing primary treatment for stage I and II breast cancer. Standardized questionnaires were sent out to 130 surgeons, 59 radiation oncologists and 89 medical oncologists. The overall response rate was 44%. Based on the frequency of follow-up visits and investigations recommended by respondents, an average cost per patient for a 5-year follow-up plan was derived for each subspecialist group: $791, $911 and $904 for surgeons, radiation oncologists and medical oncologists respectively. Use of a less interventionist follow-up program was estimated to result in a cost saving of $300 per patient over 5 years. The results indicate that, for the most part, Canadian oncologists have been influenced by the available literature concerning follow-up practices and are ordering fewer routine tests. Further cost savings to the Canadian health care system could be achieved with the adoption of even less interventionist follow-up programs.     

TLS/FUS, a pro-oncogene involved in multiple chromosomal translocations, is a novel regulator of BCR/ABL-mediated leukemogenesis

The leukemogenic potential of BCR/ABL oncoproteins depends on their tyrosine kinase activity and involves the activation of several downstream effectors, some of which are essential for cell transformation. Using electrophoretic mobility shift assays and Southwestern blot analyses with a double-stranded oligonucleotide containing a zinc finger consensus sequence, we identified a 68 kDa DNA-binding protein specifically induced by BCR/ABL. The peptide sequence of the affinity-purified protein was identical to that of the RNA-binding protein FUS (also called TLS). Binding activity of FUS required a functional BCR/ABL tyrosine kinase necessary to induce PKCbetaII-dependent FUS phosphorylation. Moreover, suppression of PKCbetaII activity in BCR/ABL-expressing cells by treatment with the PKCbetaII inhibitor CGP53353, or by expression of a dominant-negative PKCbetaII, markedly impaired the ability of FUS to bind DNA. Suppression of FUS expression in myeloid precursor 32Dcl3 cells transfected with a FUS antisense construct was associated with upregulation of the granulocyte-colony stimulating factor receptor (G-CSFR) and downregulation of interleukin-3 receptor (IL-3R) beta-chain expression, and accelerated G-CSF-stimulated differentiation. Downregulation of FUS expression in BCR/ABL-expressing 32Dcl3 cells was associated with suppression of growth factor-independent colony formation, restoration of G-CSF-induced granulocytic differentiation and reduced tumorigenic potential in vivo. Together, these results suggest that FUS might function as a regulator of BCR/ABL leukemogenesis, promoting growth factor independence and preventing differentiation via modulation of cytokine receptor expression.