Optička i električna svojstva neozračenog i rendgenskim zračenjem ozračenog PMABB

Studies of the optical and electrical (ferroelectric, electrical conductivity) properties of non- and X-ray-irradiated pentakis undecabromodibismuthate (PMABB) orthorhombic crystals were made. The crystal is anisotropic, weakly positively birefringent and optically biaxial with the optical angle 2V = 72◦ 150. The temperature dependence of linear birefringence ∆(∆nc) in the temperature range from 295 K to 320 K shows an anomaly at the phase-transition temperature Tc = 312 K, in agreement with the published result. The spontaneous polarization Ps seems slightly large in comparison with those of other ferroelectrics, owing to the strengthened packing along the polar axis. The results show that the microscopic mechanism driving the phase transition has the same influence on the spontaneous birefringence δs(∆nc) and on Ps in the compound. Effects of irradiation on the refractive indices and their dispersions as well as on the optical anisotropy and optical birefingence are studied. The coercive field Ec and the bias field Eb build up during the irradiation, while Ps shows no change with the enhanced doses until the threshold irradiation (D0 = 4 × 104 rad) is reached, then it begins to decay in a fairly rapid manner. The results are discussed in terms of the conventional double-minimum potential energy used for the description of the ferroelectric mechanism. Measurements of the electrical conductivity σ in the same temperature range show an anomaly at Tc due to the generation of protonic carriers as a result of rotational motion of cations. The maximum σ-value at the threshold irradiation D0 is observed and the variation of σ in the vicinity of D0 was studied.Proučavala su se optička i električna svojstva ortorombnih kristala pentakis undecabromodibismuthata (PMABB) prije ozračivanja i ozračenih s nekoliko doza rendgenskog zračenja. Kristali PMABB su anizotropni, malo pozitivno dvolomni i optički dvoosni s optičkim kutom 2V = 72◦ 150 . Spontana polarizacija Ps je relativno velika zbog snažnijeg slaganja vodikovim vezanjem duž polarne c-osi. Mikroskopski mehanizmi koji uzrokuju fazni prijelaz jednako utječu na Ps i na spontani dvolom δs(∆nc). Ps se ne mijenja za doze ispod kritične, DD0 smanjuje se naglo. Ishodi mjerenja se raspravljaju na osnovi dvostrukog minimuma potencijala koji se rabi za opis feroelektričnog mehanizma. Koercitivno polje Ec i polarizacijsko polje Eb rastu s ozračivanjem zbog promjena unutarnjih polja. Električna vodljivost σ pokazuje anomaliju na kritičnoj temperaturi Tc zbog stvaranja protonskih nositelja koji su posljedica zakretanja kationa. Pri DD0 smanjuje zbog djelovanja klopki

Optička i električna svojstva neozračenog i rendgenskim zračenjem ozračenog PMABB

Studies of the optical and electrical (ferroelectric, electrical conductivity) properties of non- and X-ray-irradiated pentakis undecabromodibismuthate (PMABB) orthorhombic crystals were made. The crystal is anisotropic, weakly positively birefringent and optically biaxial with the optical angle 2V = 72◦ 150. The temperature dependence of linear birefringence ∆(∆nc) in the temperature range from 295 K to 320 K shows an anomaly at the phase-transition temperature Tc = 312 K, in agreement with the published result. The spontaneous polarization Ps seems slightly large in comparison with those of other ferroelectrics, owing to the strengthened packing along the polar axis. The results show that the microscopic mechanism driving the phase transition has the same influence on the spontaneous birefringence δs(∆nc) and on Ps in the compound. Effects of irradiation on the refractive indices and their dispersions as well as on the optical anisotropy and optical birefingence are studied. The coercive field Ec and the bias field Eb build up during the irradiation, while Ps shows no change with the enhanced doses until the threshold irradiation (D0 = 4 × 104 rad) is reached, then it begins to decay in a fairly rapid manner. The results are discussed in terms of the conventional double-minimum potential energy used for the description of the ferroelectric mechanism. Measurements of the electrical conductivity σ in the same temperature range show an anomaly at Tc due to the generation of protonic carriers as a result of rotational motion of cations. The maximum σ-value at the threshold irradiation D0 is observed and the variation of σ in the vicinity of D0 was studied.Proučavala su se optička i električna svojstva ortorombnih kristala pentakis undecabromodibismuthata (PMABB) prije ozračivanja i ozračenih s nekoliko doza rendgenskog zračenja. Kristali PMABB su anizotropni, malo pozitivno dvolomni i optički dvoosni s optičkim kutom 2V = 72◦ 150 . Spontana polarizacija Ps je relativno velika zbog snažnijeg slaganja vodikovim vezanjem duž polarne c-osi. Mikroskopski mehanizmi koji uzrokuju fazni prijelaz jednako utječu na Ps i na spontani dvolom δs(∆nc). Ps se ne mijenja za doze ispod kritične, DD0 smanjuje se naglo. Ishodi mjerenja se raspravljaju na osnovi dvostrukog minimuma potencijala koji se rabi za opis feroelektričnog mehanizma. Koercitivno polje Ec i polarizacijsko polje Eb rastu s ozračivanjem zbog promjena unutarnjih polja. Električna vodljivost σ pokazuje anomaliju na kritičnoj temperaturi Tc zbog stvaranja protonskih nositelja koji su posljedica zakretanja kationa. Pri DD0 smanjuje zbog djelovanja klopki

Towards liveable volcanic cities: A look at the governance of lahars in Yogyakarta, Indonesia, and Latacunga, Ecuador

The physical and governance challenges posed by urban planning and integrated water resources management (IWRM) are gaining momentum worldwide. Yet, the governance of Volcanic River Basins (VRB) remains vastly unexplored. There are at least 500 active volcanoes worldwide, with 600 million people living near them. Through a multiple-case study methodology, we aim to contribute to the understanding of how lahar risks management is being conducted in two distinct urbanized volcanic river basins: Yogyakarta in Indonesia, and Latacunga in Ecuador. Both are located in the “ring of fire” with recent eruption threats in the last decade. The two cases were conducted independently, both triangulated by international and national literature reviews, policy analysis, and in-depth interviews. The Indonesian case study focuses on the governance intricacies for water and disaster management after 2010 eruption during pre, onset, and post-eruption. The Ecuadorian case study looks at risk governance from the perspective of households after a volcanic eruption in 2015, highlighting how bottom-up risk management strategies interact with top-down governance policies. Based on both case studies, a synthesis framework for Volcanic River Basin Management (VRBM) is formulated. This framework can be used as the way forward to analyze disaster and resources management in urbanized volcanic areas

RADIATION RISKS EVALUATION FROM PHOSPHATE ROCKS, SIBAIYA REGION, CENTRAL EASTERN DESERT, EGYPT

Radioactivity in the environment is caused by natural radiation (terrestrial and cosmic) and anthropogenic activities. The present work used the integrated carbone γ-ray Spectrome-ter data to the prospect of radioactive zones at Sibaiya area, Central Eastern Desert, Egypt

Focused molecular analysis of small cell lung cancer: feasibility in routine clinical practice

© 2015 Abdelraouf et al.Background: There is an urgent need to identify molecular signatures in small cell lung cancer (SCLC) that may select patients who are likely to respond to molecularly targeted therapies. In this study, we investigate the feasibility of undertaking focused molecular analyses on routine diagnostic biopsies in patients with SCLC. Methods: A series of histopathologically confirmed formalin-fixed, paraffin-embedded SCLC specimens were analysed for epidermal growth factor receptors (EGFR), KRAS, NRAS and BRAF mutations, ALK gene rearrangements and MET amplification. EGFR and KRAS mutation testing was evaluated using real time polymerase chain reaction (RT-PCR cobas®), BRAF and NRAS mutations using multiplex PCR and capillary electrophoresis-single strand conformation analysis, and ALK and MET aberrations with fluorescent in situ hybridization. All genetic aberrations detected were validated independently. Results: A total of 105 patients diagnosed with SCLC between July 1990 and September 2006 were included. 60 (57 %) patients had suitable tumour tissue for molecular testing. 25 patients were successfully evaluated for all six pre-defined molecular aberrations. Eleven patients failed all molecular analysis. No mutations in EGFR, KRAS and NRAS were detected, and no ALK gene rearrangements or MET gene amplifications were identified. A V600E substitution in BRAF was detected in a Caucasian male smoker diagnosed with SCLC with squamoid and glandular features. Conclusion: The paucity of patients with sufficient tumour tissue, quality of DNA extracted and low frequency of aberrations detected indicate that alternative molecular characterisation approaches are necessary, such as the use of circulating plasma DNA in patients with SCLC

Differential marker expression by cultures rich in mesenchymal stem cells

Background: Mesenchymal stem cells have properties that make them amenable to therapeutic use. However, the acceptance of mesenchymal stem cells in clinical practice requires standardized techniques for their specific isolation. To date, there are no conclusive marker (s) for the exclusive isolation of mesenchymal stem cells. Our aim was to identify markers differentially expressed between mesenchymal stem cell and non-stem cell mesenchymal cell cultures. We compared and contrasted the phenotype of tissue cultures in which mesenchymal stem cells are rich and rare. By initially assessing mesenchymal stem cell differentiation, we established that bone marrow and breast adipose cultures are rich in mesenchymal stem cells while, in our hands, foreskin fibroblast and olfactory tissue cultures contain rare mesenchymal stem cells. In particular, olfactory tissue cells represent non-stem cell mesenchymal cells. Subsequently, the phenotype of the tissue cultures were thoroughly assessed using immuno-fluorescence, flow-cytometry, proteomics, antibody arrays and qPCR. Results: Our analysis revealed that all tissue cultures, regardless of differentiation potential, demonstrated remarkably similar phenotypes. Importantly, it was also observed that common mesenchymal stem cell markers, and fibroblast-associated markers, do not discriminate between mesenchymal stem cell and non-stem cell mesenchymal cell cultures. Examination and comparison of the phenotypes of mesenchymal stem cell and non-stem cell mesenchymal cell cultures revealed three differentially expressed markers – CD24, CD108 and CD40. Conclusion: We indicate the importance of establishing differential marker expression between mesenchymal stem cells and non-stem cell mesenchymal cells in order to determine stem cell specific markers

Dystocia in Friesian cows and its effects on postpartum reproductive performance and milk production

A total of 1,243 records for 585 dairy Friesian cows from 1997–2004 were used to study the factors affecting dystocia and its effects on reproductive performance and milk production. The overall incidence of dystocia was 6.9%. The percentage of dystocia decreased with increasing live body weight, age, and parity of cows (P < 0.05); however, it increased with increasing birth weight of calves (P < 0.05). The highest percentage of dystocia was detected in winter season, but the least percentage was in summer season (P < 0.05). The percentage of incidence of dystocia was significantly (P < 0.05) higher with winter feeding compared to summer ration (8.2% vs. 5.1%). The percentage of incidence of dystocia was significantly (P < 0.05) higher with twinning than single calving (15.5% vs. 6.5%), while not significantly affected by the sex of born calves. Incidence of dystocia had adverse effects on reproductive performance and milk yield. The service interval, service period, days open, and calving interval were significantly (P < 0.05) longer in cows afflicted with dystocia compared to normal cows. The conception rate was lower (P < 0.05), but the number of service per conception was higher (P < 0.05) in cows afflicted with dystocia compared to normal cows (60.5% vs. 73.0% and 3.4 vs. 2.7, respectively). Average daily milk yield was lower (P < 0.05) by 1 kg for cows with incidence of dystocia compared to normal cows