Origin of multiple band gap values in single width nanoribbons

Deterministic band gap in quasi-one-dimensional nanoribbons is prerequisite for their integrated functionalities in high-performance molecular-electronics based devices. However, multiple band gap values commonly observed in the same width of graphene nanoribbons fabricated in same slot of the experiments remains unresolved, and raise a critical concern over scalable production of pristine and/or hetero-structure nanoribbons with deterministic properties and functionalities for plethora of applications. Here, we show that a modification in the depth of potential wells in the periodic direction of a supercell on relative shifting of passivating atoms at the edges is the origin of multiple band gap values for the same width of nanoribbons in a crystallographic orientation, although they carry practically the same ground state energy. The results are similar when calculations are extended from planar graphene to buckled silicene nanoribbons. Thus, the findings facilitate tuning of the electronic properties of quasi-one-dimensional materials such as bio-molecular chains, organic and inorganic nanoribbons by performing edge engineering.Comment: 11 pages, 6 figure

First principles investigation of topological phase in XMR material TmSb under hydrostatic pressure

In this article, we report emergence of topological phase in XMR material TmSb under hydrostatic pressure using first principles calculations. We find that TmSb, a topologically trivial semimetal, undergoes a topological phase transition with band inversion at X point without breaking any symmetry under a hydrostatic pressure of 12 GPa. At 15 GPa, it again becomes topologically trivial with band inversion at $\Gamma$ as well as X point. We find that the pressures corresponding to the topological phase transitions are far below the pressure corresponding to structural phase transition at 25.5 GPa. The reentrant behaviour of topological quantum phase with hydrostatic pressure would help in finding a correlation between topology and XMR effect through experiments.Comment: 12 pages, 4 figure

Local knowledge in community-based approaches to medicinal plant conservation: lessons from India

Community-based approaches to conservation of natural resources, in particular medicinal plants, have attracted attention of governments, non governmental organizations and international funding agencies. This paper highlights the community-based approaches used by an Indian NGO, the Rural Communes Medicinal Plant Conservation Centre (RCMPCC). The RCMPCC recognized and legitimized the role of local medicinal knowledge along with other knowledge systems to a wider audience, i.e. higher levels of government.... The review of local medicinal plant knowledge systems reveals that even though medicinal plants and associated knowledge systems (particularly local knowledge) are gaining wider recognition at the global level, the efforts to recognize and promote the un-codified folk systems of medicinal knowledge are still inadequate. In country like India, such neglect is evident through the lack of legal recognition and supporting policies. On the other hand, community-based approaches like local healers' workshops or village biologist programs implemented by RCMPCC are useful in combining both local (folk and codified) and formal systems of medicine.... Despite the high reliance on the local medicinal knowledge systems for health needs in India, the formal policies and national support structures are inadequate for traditional systems of medicine and almost absent for folk medicine. On the other hand, NGOs like the RCMPCC have demonstrated that community-based and local approaches such as local healer's workshops and village biologist program can synergistically forge linkages between local knowledge with the formal sciences (in this case botany and ecology) and generate positive impacts at various levels.https://ethnobiomed.biomedcentral.com/articles/10.1186/1746-4269-2-2

Becoming a Traditional Medicinal Plant Healer: Divergent Views of Practicing and Young Healers on Traditional Medicinal Plant Knowledge Skills in India

researchTraditional medicinal plant knowledge (TMK) helps meet the health needs of a large section of the world’s population, especially socially and economically disadvantaged and aboriginal communities of developing countries like India. However, there is little known about TMK skills and their intergenerational transfer and growing concerns over the erosion of TMK within these communities. Through indepth interviews with 33 practicing village healers from two remote and economically poor villages of Western India, we identified a set of ten crucial TMK skills and their relative importance. We then interviewed 27 young budding healers from the same villages to establish their views on crucial TMK skills. The Mann-Whitney U test was used to compare the differences in importance that old and young healers attach to TMK skills. We found that old and young healers significantly differ on ascribing importance to five crucial TMK skills, including: interest, identification, rare plants, consultation and harvesting. It was discovered that such differences in perception of old and young healers about critical TMK skills can be attributed to lack of interest by young healers in learning some TMK skills, complexity of the skills, incomplete transmission (due to stricter adherence to transmission rules by old healers) and the impact of formal schooling and modern medicines in generating negative values among young healers towards learning new TMK skills

Metal-insulator transitions in tetrahedral semiconductors under lattice change

Although most insulators are expected to undergo insulator to metal transition on lattice compression, tetrahedral semiconductors Si, GaAs and InSb can become metallic on compression as well as by expansion. We focus on the transition by expansion which is rather peculiar; in all cases the direct gap at $\Gamma$ point closes on expansion and thereafter a zero-gap state persists over a wide range of lattice constant. The solids become metallic at an expansion of 13 % to 15 % when an electron fermi surface around L-point and a hole fermi surface at $\Gamma$-point develop. We provide an understanding of this behavior in terms of arguments based on symmetry and simple tight-binding considerations. We also report results on the critical behavior of conductivity in the metal phase and the static dielectric constant in the insulating phase and find common behaviour. We consider the possibility of excitonic phases and distortions which might intervene between insulating and metallic phases.Comment: 12 pages, 8 figure

Reacquiring a taste for Diversity: Changing food habits, their casual factors, and the value of dietary diversity in Jumla, Nepal

Understanding local food systems including food habit changes and the factors contributing to these changes is critical to ensuring effective interventions of food security. While diversity of foods is widely recognized as an important aspect of sustainable diets and food security, the value people place on dietary diversity is rarely considered in local interventions. In the remote, high-hill district of Jumla in Nepal, diversity is particularly important for food security. Despite this, many people choose to eat the same meal of dalbhat twice a day, leaving to question the value they have for dietary diversity. This has implications for the interventions used by policymakers and practitioners to address issues of food insecurity. This study examines community-perceived food habit changes and the factors contributing to these changes in Jumla, in addition to the value people place on dietary diversity. A participatory research approach employing eight focus group discussions was used to elicit and examine community perceptions. A variety of causal factors were cited as responsible for changes in both consumption and production of food over the past sixty years, particularly the onset of pests and diseases, the effects of climate change, and food aid. While access and availability pose major barriers to dietary diversity in Jumla, persistent food habits were found to underlie consumption patterns. It is therefore necessary that the production and markets for local foods are enhanced, development and food security are planned collectively, and new cooking methods and recipes are promoted to enable people to reacquire a taste for diversity

Erythrocyte membrane fatty acid profile and saturation index in gallbladder carcinogenesis: a case-control study

BACKGROUND: Gallbladder cancer is a common neoplasm of biliary tract, with an unknown etiology. PATIENTS AND METHODS: This study was carried out to evaluate the changes in the membrane fatty acid profile and saturation index in patients with gallbladder cancer. The study sample consisted of 50 newly diagnosed cases of gallbladder cancer and 50 patients undergoing cholecystectomy for cholelithiasis were recruited as controls. The fatty acid estimation was carried out by high performance liquid chromatography (HPLC). Statistical analysis was carried out by student 't' test and one-way ANOVA. Pearson's correlation coefficient was also obtained. RESULTS: A significant lowering of erythrocyte membrane stearic acid (p = 0.000), arachidonic acid (p = 0.001), and saturation index (p = 0.001) was observed in patients with gallbladder cancer compared to controls. A significant inverse relation was observed between stearic and oleic acid (r = -0.269 p = 0.007). CONCLUSION: Results of the present study suggest an increase in the delta 9 desaturation in cancer patients compared to controls however, a possible role of biliary stasis due to altered gallbladder motility or derangements of signal transduction secondary to altered membrane lipid bilayer cannot be ruled out