Effective charging energy for a regular granular metal array

We study the Ambegaokar-Eckern-Sch\"{o}n (AES) model for a regular array of metallic grains coupled by tunnel junctions of conductance $g$ and calculate both paramagnetic and diamagnetic terms in the Kubo formula for the conductivity. We find analytically, and confirm by numerical path integral Monte Carlo methods, that for $0<g<4$ the conductivity obeys an Arrhenius law $\sigma(T)\sim\exp[-E^{*}(g)/T]$ with an effective charging energy $E^{*} (g)$ when the temperature is sufficiently low, due to a subtle cancellation between $T^2$ inelastic-cotunneling contributions in the paramagnetic and diamagnetic terms. We present numerical results for the effective charging energy and compare the results with recent theoretical analyses. We discuss the different ways in which the experimentally observed $\sigma(T)\sim\exp[-\sqrt{T_{0}/T}]$ law could be attributed to disorder.Comment: 5 pages, 3 figures, ReVTeX; added estimates of effective charging energies and discussion of effects of disorde

Byssoloma subdiscordans (Nyl.) P. James: Distributional range and its habitat preference in Indian subcontinent

The present paper deals with the new distributional record of Byssoloma subdiscordans for Western Himalayan lichen flora and a new habitat record for Indian subcontinent. A note on its brief taxonomic description, distribution, ecology and occurrence in India is also provided. Previously the species was reported as corticolous and foliicolous from tropical and montane regions of India, viz. Eastern Himalaya and Western Ghats, but this is for the first time that authors have reported it as saxicolous in temperate regions of Western Himalaya, thus extending its habitat preference along with distributional range within Indian subcontinent

Assessment of tree diversity in tropical moist deciduous forest of Mizoram University, Northeast India

Forests are the main repository of biodiversity and play an important role in maintaining the ecological balance of nature. The status of species diversity reflects the health of the ecosystem. Therefore, the information on variation in the flora, for example,  species composition, diversity and the basal area within any ecosystem like the forest of Mizoram University campus, Tanhril village, Aizawl would be important in understanding the forest wealth of the campus. Keeping in view, the study was analyzed the composition and diversity of  Mizoram University campus by laying 16 (10 m ×10 m) quadrats at random locations during 2015-2016. A total of 35 tree species belonging to 30 genera and 22 families were recorded in the forest communities of University Campus. Aporusa octandra was the most dominant tree species with maximum 31.50 importance value index (IVI), 3.29 Shannon diversity index (H0) and 6972 Simpson’s index (D) followed by Castanopsis tribuloides (28 IVI, 0.22 H0 and 5256 D) and least dominant species recorded were: Albizia odoratissima, Anogeissus acuminate, Lithocarpus elegans, Oroxylum indicum. This study suggests that the forest patches are recovering after the establishment of the University because of adequate protection which was degraded in the past by the villager for collecting the trees for firewood, edible wild food and selecting the mature trees for felling. Therefore, further studies on regeneration potential of tree species would be crucial for the conservation of ecologically important species and to assess rates of their recovery following the disturbance

ETHNOMEDICINAL, PHYTOCHEMICAL AND PHARMACOLOGICAL ASPECTS OF FLACOURTIA JANGOMAS: A REVIEW

Flacourtia jangomas (Lour.) Raeusch., a small tree of Willow family distributed throughout tropical regions of East Africa and Asia is well-known for its culinary and medicinal uses. The plant has received increasing interest due to its limonoid constituents. Phytochemical studies have led to the isolation and characterization of an array of bioactive compounds and pharmacological investigations have validated the traditional uses of the species as well as discovered some new bioefficacies. The aim of the review is to present an updated and comprehensive overview of traditional uses, ethnomedicinal significance, phytochemical and pharmacological aspects of F. jangomas to highlight its ethnopharmacological use and to explore its therapeutic potentials thereby providing a basis for future research. Relevant information and literature on F. jangomas from electronic databases such as Academic Journals, Google, Google Scholar, PubMed, Web of Science, and Science Direct were consulted and analyzed. Available literatures evidently demonstrate that F. jangomas possess a wide spectrum of pharmacological activities that could be explained by the presence of varied range of chemical constituents. Phytochemical and pharmacological investigations showed that extracts of different parts and major active components of F. jangomas had antimicrobial, analgesic, antidiabetic, antidiarrheal, antioxidant and cytotoxic activities. This emphasizes the need for further investigation to explore more bioactive chemical constituents and new bioefficacies of the plant and to establish a credible relationship between molecular structure and activity of compounds

ANTIFUNGAL ACTIVITY OF NATURAL COLOURANT FROM MELIA COMPOSITA BARK AND ITS APPLICATION IN FUNCTIONAL TEXTILE FINISHING

Objective: The present study was aimed to evaluate the antifungal efficacy of natural dye obtained from Melia composita bark and its impact on the antimicrobial finishing of different types of textile fabrics.Methods: Antifungal activity of M. composita bark dye was assessed against standard strains of five fungi namely Aspergillus flavus, A. niger, A. parasiticus, Fusarium moniliforme and Penicillium canescens using agar-well diffusion method. The minimum inhibitory concentration (MIC) was determined by broth dilution method. The antifungal potency of dyed fabrics (silk, wool, and cotton) against the five test fungi was quantitatively evaluated by reported method.Results: Different treatment doses of natural dye exhibited a varying degree of antifungal activity against the five test fungi. The treatment dose of 100 mg/ml and above were considerably active. Growth inhibition impact of natural dye at 250 mg/ml dose was almost at par with positive control. Maximum growth inhibition in all the five test fungi was evident with 500 mg/ml dose followed by 250 and 100 mg/ml. MIC of the natural dye against test fungi were found in the range of 20.50-23.00 mg/ml. Dyed fabrics of silk, wool, and cotton also showed remarkable antifungal efficacy against all the test fungi. The highest growth reduction was observed in A. parasiticus whereas lowest in P. canescens with the three types of dyed fabrics. Dyed wool fabrics exhibited the maximum growth reduction followed by silk and cotton fabrics.Conclusion: The study revealed the remarkable antifungal activity of natural dye from barks of M. composita; therefore, the plant can be considered as a good source of natural dye with functional properties and can be used in commercial dyeing and protective finishing of different kinds of textile fabrics.Keywords: Melia composita, Bark, Natural Dye, Dyed Fabrics, Antifungal activityÂ

Correlation of Doppler assessment of fetal aortic isthmus with perinatal outcome in intrauterine growth restriction

Background: The objective of the present study was to find out association between aortic isthmus Doppler changes and perinatal outcome in growth restricted fetuses with placental insufficiency.Methods: It is a prospective case control study, cases were 43 pregnant women with fetal growth restriction (FGR) with abnormal umbilical artery (UA) Doppler while 43 pregnant women with FGR but normal UA doppler, matched with period of gestation were taken as control. The direction of blood flow in aortic isthmus studied which may be antegrade, absent or retrograde and correlation between qualitative parameters of umbilical artery, aortic isthmus and ductus venosus were studied. Quantitative parameters, PI and RI were also calculated. Patients were managed as per hospital protocols. Perinatal outcome and any adverse event e.g. stillbirth, neonatal death, respiratory distress syndrome, intensive care unit stay >14 days etc. was noted.Results: The number of intrauterine death (IUD) and still birth was increased in women with absent and retrograde flow in aortic isthmus, 66.7% and 71.4% respectively (p value <0.001). Retrograde blood flow in the aortic isthmus is consistently associated with absent or reverse end diastolic velocity in umbilical artery and ductus venosus.Conclusions: Doppler of aortic isthmus is an additional parameter to assess severity of FGR. It plays an important role in termination of preterm FGR fetuses

Coulomb blockade and quantum tunnelling in the low-conductivity phase of granular metals

We study the effects of Coulomb interaction and inter-grain quantum tunnelling in an array of metallic grains using the phase-functional approach for temperatures $T$ well below the charging energy $E_{c}$ of individual grains yet large compared to the level spacing in the grains. When the inter-grain tunnelling conductance $g\gg1$, the conductivity $\sigma$ in $d$ dimensions decreases logarithmically with temperature ($\sigma/\sigma_{0}\sim1-\frac{1}{2\pi gd}\ln(gE_{c}/T)$), while for $g\to0$, the conductivity shows simple activated behaviour ($\sigma \sim \exp(-E_c/T)$). We show, for bare tunnelling conductance $g \gtrsim 1$, that the parameter $\gamma \equiv g(1-2/(g\pi)\ln(gE_{c}/T))$ determines the competition between charging and tunnelling effects. At low enough temperatures in the regime $1\gtrsim \gamma \gg 1/\sqrt{\beta E_{c}}$, a charge is shared among a finite number $N=\sqrt{(E_{c}/T)/\ln(\pi/2\gamma z)}$ of grains, and we find a soft activation behaviour of the conductivity, $\sigma\sim z^{-1}\exp(-2\sqrt{(E_{c}/T)\ln(\pi/2\gamma z)})$, where $z$ is the effective coordination number of a grain.Comment: 11 pages REVTeX, 3 Figures. Appendix added, replaced with published versio

Ion-beam-assisted fabrication and manipulation of metallic nanowires

Metallic nanowires (NWs) are the key performers for future micro/nanodevices. The controlled manoeuvring and integration of such nanoscale entities are essential requirements. Presented is a discussion of a fabrication approach that combines chemical etching and ion beam milling to fabricate metallic NWs. The shape modification of the metallic NWs using ion beam irradiation (bending towards the ion beam side) is investigated. The bending effect of the NWs is observed to be instantaneous and permanent. The ion beam-assisted shape manoeuvre of the metallic structures is studied in the light of ion-induced vacancy formation and reconfiguration of the damaged layers. The manipulation method can be used for fabricating structures of desired shapes and aligning structures at a large scale. The controlled bending method of the metallic NWs also provides an understanding of the strain formation process in nanoscale metals