Effect of Composition on Optical and Thermoelectric Properties of Microstructured p-type (Bi2Te3)x(Sb2Te3)1 – x Alloys

Semiconducting (Bi2Te3)x(Sb2Te3)1 – x alloys are among the best thermoelectric materials available today near room temperature. This property is largely attributed to compositional variations, resulting in improved figure of merit. Considering this, present study aimed at characterizing the optical and thermoelectric properties of microstructured p-type (Bi2Te3)x(Sb2Te3)1 – x alloys for enhanced thermoelectric efficiency. High performance microstructured p-type (Bi2Te3)x(Sb2Te3)1 – x alloys were prepared by melting technique. The phase, optical band gap, microstructure, carrier type concentration and thermoelectric properties of the prepared alloys were systematically investigated by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, hot probe p-n type tester, four-probe method, κ-probe method and Seebeck coefficient measurement system. The electrical conductivity and Seebeck coefficient were measured in the temperature range 298-473 K to elucidate the Sb content effect on the thermoelectric properties of the p-type (Bi2Te3)x(Sb2Te3)1 – x alloys. The optical band gap decreased with increasing Sb content. Also, with the increase of Sb content, the electrical conductivity increased substantially, the thermal conductivity increased significantly and the Seebeck coefficient decreased marginally, which lead to a great improvement in the thermoelectric figure of merit. The maximum power factor of 3.2 × 10 – 3 Wm – 1K – 2 and figure of merit of 0.72 were obtained at 300 K for the composition of 15 %Bi2Te3-85 %Sb2Te3. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3582

Arc discharge synthesis of CNTs in hydrogen environment in presence of magnetic field

In this study the effect of hydrogen ambient environment on the growth of carbon nanotubes by arc discharge plasma in presence of external magnetic field is investigated. The samples collected from cathode deposit are analyzed by field emission scanning electron microscopy and Raman spectroscopy. Results show an increase in carbon nanotube growth with increase in hydrogen ambient pressure. The magnetic field considerably enhances the growth of carbon nanotube as observed in FESEM micrographs. In Raman spectrum, high intensity of G peak as compared to D peak indicates the presence of high quality nanotubes. Magnetic effect remarkably decreases ID/IG ratio from 1.55 to 0.31 for ambient pressure 10 mbar

PHYLLOIDES TUMOUR: REVIEW OF AN UNCOMMON BREAST PATHOLOGY AT A SPECIALIZED CANCER CENTRE

Purpose: Phyllodes tumours are rare breast tumours that comprise almost 1% of breast tumours. The outcome for these tumours is generally considered better than breast cancers. We review the cases of phyllodes tumour presenting to a specialised cancer centre over a 14 year period. Materials and Methods: All case records with the diagnosis of phyllodes tumour between 1999 and 2012 were retrieved from the cancer registry. Patient demographics, tumour site, size, axillary lymph node status, whether primary or recurrent, metastatic status, histological type, type of surgery, any complication, margin positivity, post-operative radiation therapy, local or distant recurrence, morality and follow-up duration were recorded. Data were analysed using SPSS. Results: A total of 77 cases of phyllodes tumour were seen between 1999 and 2012. All patients were female with a mean age of 39.9 years. All patients presented with a breast lump with median duration of 8 months. Almost two-thirds (65%) of the patients presented with primary tumour compared to 10% recurrent tumours and the rest were referred after surgery outside. Median size on histopathology was 5 cm (IQR 3.5–8.5 cm). Over a median follow-up duration of 31 months (IQR 9–48 months), 69 patients (89.6%) were alive, while 3 patients (3.9%) did not survive and 5 patients (6.4%) were lost to follow-up. Recurrence was seen in 10 (13%) patients with median time to recurrence of 12 months (IQR 7–24). Involved axillary lymph nodes and borderline or malignant histopathology were found to be signi cantly associated with recurrence (P = 0.04), while margin positivity, post operative radiation therapy and histopathology were not signi cantly associated with recurrence. Conclusion: Phyllodes tumour is an uncommon breast tumour that is predominantly treated with surgical excision. Although survival with these tumours is better compared to breast cancers, involvement of axillary nodes and borderline or malignant histopathology confer an increased risk of recurrence in these patients. Key words: Breast cancer, phyllodes tumours, survival

Multi-walled carbon nanotubes grow under low pressure hydrogen, air, and argon ambient by arc discharge plasma

Multi-walled carbon nanotubes (MWCNTs) were grown on cathode deposit by arc discharge plasma under H2, Ar, and air ambient environment. The influence of ambient gas pressure on the structure and physical properties of carbon nanotube were compared. Herein, we highlight the influence of ambient environment and pressure to grow high quality carbon nanotubes. Field emission scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and X-ray diffraction were used for structural characterization and yield determination. The result revealed that background gas and pressure were crucial factor for growing highly crystalline and highly graphitic with ID/IG ratio 0.237 obtained for MWCNTs’ synthesized in H2 environment with extreme low defects

INVESTIGATION ON THE PRODUCTION OF L-GLUTAMINASE FROM PSEUDOMONAS STUTZERI STRAIN UNDER SOLID STATE FERMENTATION USING VARIOUS AGRO RESIDUES

Solid state fermentation was carried out for the production of L-glutaminase by Pseudomonas stutzeri PIMS6 using different agro residues including green gram husk, Bengal gram husk, cattle feed, wheat bran and groundnut oil cake as solid substrates. L-glutaminase has received significant attention in recent years owing to its potential applications in medicine as an anticancer agent, as an efficient anti-retroviral agent and as a biosensor. In food industries it is used as a flavor and aroma enhancing agent. The maximum yield (55.24 U/gds) of L-glutaminase by Pseudomomonas stutzeri PIMS6 was obtained using cattle feed at 75% initial moisture content, initial pH 8.0, supplemented with glucose (1.0%), ammonium sulphate (1.0%),  inoculated with 5% of inoculum and incubated at 37°C for 96 h. Both physico-chemical and nutritional parameters played a significant role in the production of the enzyme L-glutaminase.Keywords: L-glutaminase, Pseudomonas stutzeri PIMS6, Cattle feed, Solid state fermentation

Hypoxia, Snail and incomplete epithelial–mesenchymal transition in breast cancer

BACKGROUND: Hypoxia is an element of the tumour microenvironment that impacts upon numerous cellular factors linked to clinical aggressiveness in cancer. One such factor, Snail, a master regulator of the epithelial-mesenchymal transition (EMT), has been implicated in key tumour biological processes such as invasion and metastasis. In this study we set out to investigate regulation of EMT in hypoxia, and the importance of Snail in cell migration and clinical outcome in breast cancer. METHODS: Four breast cancer cell lines were exposed to 0.1% oxygen and expression of EMT markers was monitored. The migratory ability was analysed following Snail overexpression and silencing. Snail expression was assessed in 500 tumour samples from premenopausal breast cancer patients, randomised to either 2 years of tamoxifen or no adjuvant treatment. RESULTS: Exposure to 0.1% oxygen resulted in elevated levels of Snail protein, along with changes in vimentin and E-cadherin expression, and in addition increased migration of MDA-MB-468 cells. Overexpression of Snail increased the motility of MCF-7, T-47D and MDA-MB-231 cells, whereas silencing of the protein resulted in decreased migratory propensity of MCF-7, MDA-MB-468 and MDA-MB-231 cells. Moreover, nuclear Snail expression was associated with tumours of higher grade and proliferation rate, but not with disease recurrence. Interestingly, Snail negativity was associated with impaired tamoxifen response (P = 0.048). CONCLUSIONS: Our results demonstrate that hypoxia induces Snail expression but generally not a migratory phenotype, suggesting that hypoxic cells are only partially pushed towards EMT. Furthermore, our study supports the link between Snail and clinically relevant features and treatment response

Bicalutamide-induced hypoxia potentiates RUNX2-mediated Bcl-2 expression resulting in apoptosis resistance.

BACKGROUND: We have previously shown that hypoxia selects for more invasive, apoptosis-resistant LNCaP prostate cancer cells, with upregulation of the osteogenic transcription factor RUNX2 and the anti-apoptotic factor Bcl-2 detected in the hypoxia-selected cells. Following this observation, we questioned through what biological mechanism this occurs. METHODS: We examined the effect of hypoxia on RUNX2 expression and the role of RUNX2 in the regulation of Bcl-2 and apoptosis resistance in prostate cancer. RESULTS: Hypoxia increased RUNX2 expression in vitro, and bicalutamide-treated LNCaP tumours in mice (previously shown to have increased tumour hypoxia) exhibited increased RUNX2 expression. In addition, RUNX2-overexpressing LNCaP cells showed increased cell viability, following bicalutamide and docetaxel treatment, which was inhibited by RUNX2 siRNA; a range of assays demonstrated that this was due to resistance to apoptosis. RUNX2 expression was associated with increased Bcl-2 levels, and regulation of Bcl-2 by RUNX2 was confirmed through chromatin immunoprecipitation (ChIP) binding and reporter assays. Moreover, a Q-PCR array identified other apoptosis-associated genes upregulated in the RUNX2-overexpressing LNCaP cells. CONCLUSION: This study establishes a contributing mechanism for progression of prostate cancer cells to a more apoptosis-resistant and thus malignant phenotype, whereby increased expression of RUNX2 modulates the expression of apoptosis-associated factors, specifically Bcl-2

Identification of Hypoxia-Regulated Proteins Using MALDI-Mass Spectrometry Imaging Combined with Quantitative Proteomics

Hypoxia is present in most solid tumors and is clinically correlated with increased metastasis and poor patient survival. While studies have demonstrated the role of hypoxia and hypoxia-regulated proteins in cancer progression, no attempts have been made to identify hypoxia-regulated proteins using quantitative proteomics combined with MALDI-mass spectrometry imaging (MALDI-MSI). Here we present a comprehensive hypoxic proteome study and are the first to investigate changes in situ using tumor samples. In vitro quantitative mass spectrometry analysis of the hypoxic proteome was performed on breast cancer cells using stable isotope labeling with amino acids in cell culture (SILAC). MS analyses were performed on laser-capture microdissected samples isolated from normoxic and hypoxic regions from tumors derived from the same cells used in vitro. MALDI-MSI was used in combination to investigate hypoxia-regulated protein localization within tumor sections. Here we identified more than 100 proteins, both novel and previously reported, that were associated with hypoxia. Several proteins were localized in hypoxic regions, as identified by MALDI-MSI. Visualization and data extrapolation methods for the in vitro SILAC data were also developed, and computational mapping of MALDI-MSI data to IHC results was applied for data validation. The results and limitations of the methodologies described are discussed. 2014 American Chemical Societ