Strain-driven light polarization switching in deep ultraviolet nitride emitters

Residual strain plays a critical role in determining the crystalline quality of nitride epitaxial layers and in modifying their band structure; this often leads to several interesting physical phenomena. It is found, for example, that compressive strain in AlxGa1-xN layers grown on AlyGa1-yN (x<y) templates results in an anti-crossing of the valence bands at considerably much higher Al composition than expected. This happens even in the presence of large and negative crystal field splitting energy for AlxGa1-xN layers. A judicious magnitude of the compressive strain can support vertical light emission (out of the c-plane) from AlxGa1-xN quantum wells up to x\approx 0.80, which is desirable for the development of deep ultraviolet light-emitting diodes designed to operate below 250nm with transverse electric polarization characteristics

Radiating spherical collapse with heat flow

We present here a simple model of radiative gravitational collapse with radial heat flux which describes qualitatively the stages close to the formation of a superdense cold star. Starting with a static general solution for a cold star, the model can generate solutions for the earlier evolutionary stages. The temporal evolution of the model is specified by solving the junction conditions appropriate for radiating gravitational collapse.Comment: 13 pages, including 3 figures, submitted to IJMP-

Extractive spectrophotometric method for the determination of carbaryl in environmental samples

In the view of the potential hazards associated with the widespread use of carbaryl insecticide, a new simple extractive spectrophotometric method has been developed for its determination in environmental samples viz. soil, water and foodstuffs for its safer and more effective use. The proposed method is based on the microwave assisted alkaline hydrolysis of the insecticide to methylamine. The later is measured as methyl isobutyl ketone (MIBK) extractable yellow nickel(II)-methyldithiocarbamate complex at 380 nm through the reaction with carbon disulfide and nickel(II) acetate. The insecticide can be determined in the linearity range from 2.01 to 60.3 µg mL-1 with a correlation coefficient of 0.996. The method has been applied to the analysis of carbaryl in its commercial formulation and its recovery from vegetable and water samples for monitoring health hazards. Recoveries of the insecticide from vegetables and spiked water samples were good, ranging from 87.6-92.8%, with RSDs ranging from 0.54-1.02%. The method has also been validated for investigating the sorption of carbaryl on five soils with different characteristics to evaluate its leaching behaviour which is a measure of ground and surface water contamination. The leaching potential of the insecticide in terms of groundwater ubiquity score (GUS) has values in the range 1.8-2.2 classifying it as transition leacher hence it has potential to contaminate groundwater. KEY WORDS: Carbaryl, Spectrophotometry, Environmental toxicity, Soil-sorption study, Leaching/GUS Bull. Chem. Soc. Ethiop. 2015, 29(2), 173-186DOI: http://dx.doi.org/10.4314/bcse.v29i2.

High speed hydrogen/graphite interaction

Various aspects of a research program on high speed hydrogen/graphite interaction are presented. Major areas discussed are: (1) theoretical predictions of hydrogen/graphite erosion rates; (2) high temperature, nonequilibrium hydrogen flow in a nozzle; and (3) molecular beam studies of hydrogen/graphite erosion

Thermodynamic equilibrium and its stability for Microcanonical systems described by the Sharma-Taneja-Mittal entropy

It is generally assumed that the thermodynamic stability of equilibrium state is reflected by the concavity of entropy. We inquire, in the microcanonical picture, on the validity of this statement for systems described by the bi-parametric entropy $S_{_{\kappa, r}}$ of Sharma-Taneja-Mittal. We analyze the ``composability'' rule for two statistically independent systems, A and B, described by the entropy $S_{_{\kappa, r}}$ with the same set of the deformed parameters. It is shown that, in spite of the concavity of the entropy, the ``composability'' rule modifies the thermodynamic stability conditions of the equilibrium state. Depending on the values assumed by the deformed parameters, when the relation $S_{_{\kappa, r}}({\rm A}\cup{\rm B})> S_{_{\kappa, r}}({\rm A})+S_{_{\kappa, r}}({\rm B})$ holds (super-additive systems), the concavity conditions does imply the thermodynamics stability. Otherwise, when the relation $S_{_{\kappa, r}}({\rm A}\cup{\rm B})<S_{_{\kappa, r}}({\rm A})+S_{_{\kappa, r}}({\rm B})$ holds (sub-additive systems), the concavity conditions does not imply the thermodynamical stability of the equilibrium state.Comment: 13 pages, two columns, 1 figure, RevTex4, version accepted on PR

Evidence of robust 2D transport and Efros-Shklovskii variable range hopping in disordered topological insulator (Bi2Se3) nanowires

We report the experimental observation of variable range hopping conduction in focused-ion-beam (FIB) fabricated ultra-narrow nanowires of topological insulator (Bi2Se3). The value of the exponent in the hopping equation was extracted as ~ 1/2 for different widths of nanowires, which is the proof of the presence of Efros-Shklovskii hopping transport mechanism in a strongly disordered system. High localization lengths (0.5nm, 20nm) were calculated for the devices. A careful analysis of the temperature dependent fluctuations present in the magnetoresistance curves, using the standard Universal Conductance Fluctuation theory, indicates the presence of 2D topological surface states. Also, the surface state contribution to the conductance was found very close to one conductance quantum. We believe that our experimental findings shed light on the understanding of quantum transport in disordered topological insulator based nanostructures.Comment: 14pages, 4 figure

Review of Existing Energy Framework for Vietnam

Since introducing a market-orientation to the economy in 1986, Vietnam has made considerable socioeconomic progress. For example, over the period 1986-2007, the GDP of Vietnam has grown at approximately 7 per cent per year which is the highest growth rate in the ASEAN region. In this growth, the countryâs energy sector has played a vital role. This role is likely to deepen in the years to come as Vietnam strives to achieve ever higher economic progress. Such deepening in the role of energy, this paper argues, will heighten concerns about the security of energy supply, increased CO2 emissions and pollution and other social and political challenges. In order to address these challenges, Vietnam has over the last decade, initiated several energy policies underpinned by appropriate legislation â called, âinstitutional frameworkâ, in the context of this paper. A deeper review of this framework suggests that it is typified by a lack of cohesiveness of policy direction and purpose, fragmented institutional structures and responsibilities, and weak public constituency on environmental issues. The existing framework is therefore unlikely to be able to provide a satisfactory redress to the challenges noted above. This paper provides some suggestions to reduce the weaknesses of the existing framework. These include: articulating the significance of the link between energy, economy and environment; developing coherence in institutional purpose and design, and raising public awareness through better communication and education

The number of privately treated tuberculosis cases in India: an estimation from drug sales data

Background Understanding the amount of tuberculosis managed by the private sector in India is crucial to understanding the true burden of the disease in the country, and thus globally. In the absence of quality surveillance data on privately treated patients, commercial drug sales data offer an empirical foundation for disease burden estimation. Methods We used a large, nationally representative commercial dataset on sales of 189 anti-tuberculosis products available in India to calculate the amount of anti-tuberculosis treatment in the private sector in 2013–14. We corrected estimates using validation studies that audited prescriptions against tuberculosis diagnosis, and estimated uncertainty using Monte Carlo simulation. To address implications for numbers of patients with tuberculosis, we explored varying assumptions for average duration of tuberculosis treatment and accuracy of private diagnosis. Findings There were 17·793 million patient-months (95% credible interval 16·709 million to 19·841 million) of anti-tuberculosis treatment in the private sector in 2014, twice as many as the public sector. If 40–60% of private-sector tuberculosis diagnoses are correct, and if private-sector tuberculosis treatment lasts on average 2–6 months, this implies that 1·19–5·34 million tuberculosis cases were treated in the private sector in 2014 alone. The midpoint of these ranges yields an estimate of 2·2 million cases, two to three times higher than currently assumed. Interpretation India's private sector is treating an enormous number of patients for tuberculosis, appreciably higher than has been previously recognised. Accordingly, there is a re-doubled need to address this burden and to strengthen surveillance. Tuberculosis burden estimates in India and worldwide require revision

Culture and physiological variability in Rhizoctonia solani, responsible for foliar and lesions on aerial part of soybean

Foliar blight of soybean is one of the major fungal diseases. Rhizoctonia solani isolated from soybean growing in tarai regions of Uttarakhand. Six isolates of R. solani has been characterized on the basis of cultural and physiological nature such as colony diameter, growth, colour and sclerotia formation were recorded. Potato Dextrose Agar (PDA) was found best for growth and development. Two isolates (Lakhimpur and Pantnagar) covered the whole plates (90 mm) in 48 hrs. However, maximum number of sclerotia and weight was recorded on Czapek Dox agar medium. Overall radial growth supporting is recorded Corn Meal Agar Medium. Varied range of temperatures i.e. 10, 15, 25, 30, 35 and 400C was tested and found better growth of different isolates of R. solani at 10 - 400C, with an optimum growth temperature at 300C. Isolates were grown on five broth media (Asthana &amp; Hawkers, Potato Dextrose Agar, Czapek’s Dox Agar, Corn Meal Agar and Richards Agar) for fresh, dry weight and oat meal broth culture filtrates of all isolates was used in phytotoxic effects. It recorded that maximum fresh and dry weight was observed on corn meal agar medium. The maximum reduction in radical and plumule length of germinating seeds were recorded in Haldichaur isolate