Nature of sorption of trivalent arsenic on novel iron oxyhydroxide stabilized starch/OMMT composite: A mechanistic approach

Materials which are chemically, energetically and operationally acceptable for arsenic water treatment are highly required. In this study a hybrid material (SICC) of aminated starch, oxyhydroxide of iron and OMMT clay has been demonstrated for arsenic treatment. This new material was highly efficient in arsenic water treatment which could reduce arsenic concentration far below detection limits. All binding interactions during material preparation and arsenic sorption were exclusively characterized with FT-IR, XRD and other spectroscopic tools. A molecular modeling on the basis of density functional theory was carried out to verify the above findings. Influence of material dose, treatment time, initial ion concentration, varying temperatures, etc., on extent of sorption was studied in detail. The thermodynamic parameters viz. ΔG (>-11 kJ/mol), ΔH (42.48 kJ/mol), ΔS (177.6 JK^-1 mol^-1) and E a (59.16 kJ/mol) determined the feasibility of the process, its endothermic behavior and most importantly the chemical nature of the sorption accompanied by ion-exchange to some extent. The sorption followed a monolayer chemisorption pattern as determined by the Langmuir model (R² = 0.973, R L = 0.081) with a q_max = 2.04 at 303 K. The binding of As(III) on the material was governed by a pseudo second order kinetic model.

Endotheliotropic herpesvirus infection in Asian elephants (Elephas maximus) of Assam, India

Background and Aim:

Elephant endotheliotropic herpesvirus (EEHV) is an emerging disease of elephant. Therefore, a study was conducted to know the actual status of the disease in Assam State of India.

Materials and Methods:

A total of 289 Asian elephants of Assam were screened during 2 years of study from April 2017 to March 2019. The clinical symptoms of diseased as well as gross and histopathological changes of dead elephants were recorded for the diagnosis of the disease. Virus involved in the occurrence of the disease was confirmed by polymerase chain reaction (PCR).

Results:

In the present study, a total of three elephant calves out of 22 were found positive to EEHV1A. On the other hand, three adult asymptomatic elephants were also found positive for EEHV1 on screening 267 captive Asian elephants of Assam. The amplified PCR product showed band size of 520, 600, and 930 bp. The PCR amplified product with size 600 bp had shown the gene sequence for EEHV1U77/HEL. Gross lesions include congested blood vessels of the liver and intestinal mucosa, foci of petechiae in the spleen, and heart and focal ulceration in the dorsal surface of the tongue. Microscopically, the kidneys showed intertubular edema and focal areas of degeneration associated with coagulative necrosis of the tubular epithelium. The liver showed hydropic degeneration and fatty changes of the hepatocytes. There was a massive proliferation of fibroblasts in the interlobular spaces which penetrated the necrosed areas of the hepatic lobules.

Conclusion:

A total of three wild rescued elephant calves and three asymptomatic adults were found positive for EEHV1A during the 2 years of study. The PCR amplified product with size 600 bp had shown the gene sequence for EEHV1U77/HEL.

Magnetoquantum Oscillations at THz Frequencies in InSb

The ac magnetoconductance of bulk InSb at THz frequencies in high magnetic fields, as measured by the transmission of THz radiation, shows a field-induced transmission, which at high temperatures (≈100  K) is well explained with classical magnetoplasma effects (helicon waves). However, at low temperatures (4 K), the transmitted radiation intensity shows magnetoquantum oscillations that represent the Shubnikov-de Haas effect at THz frequencies. At frequencies above 0.9 THz, when the radiation period is shorter than the Drude scattering time, an anomalously high transmission is observed in the magnetic quantum limit that can be interpreted as carrier localization at high frequencies.

Terahertz lattice dynamics of the potassium rare-earth binary molybdates

We report a systematic study of low-energy lattice vibrations in the layered systems KY(MoO₄)₂, KDy(MoO₄)₂, KEr(MoO₄)₂, and KTm(MoO₄)₂. A layered crystal structure and low symmetry of the local environment of the rare-earth ion cause the appearance of vibrational and electronic excitations in Terahertz frequencies. The interaction between these excitations leads to sophisticated dynamical properties, including non-linear effects in paramagnetic resonance spectra. The THz study in magnetic field allows for the clear distinction between lattice vibrations and electronic excitations. We measured the THz transmission spectra and show that the low energy lattice vibrations in binary molybdates can be well described within the quasi-one-dimensional model. The developed model describes the measured far-infrared spectra, and results of our calculations agree with previous Raman and ultrasound studies.

Larvicidal activity of few select indigenous plants of North East India against disease vector mosquitoes (Diptera: Culicidae)

Mosquitoes are the vectors of several life threatening diseases like dengue, malaria, Japanese encephalitis and lymphatic filariasis, which are widely present in the north-eastern states of India. Investigations on five local plants of north-east India, selected on the basis of their use by indigenous communities as fish poison, were carried out to study their mosquito larvicidal potential against Anopheles stephensi (malaria vector), Stegomyia aegypti (dengue vector) and Culex quinquefasciatus (lymphatic filariasis vector) mosquitoes. Crude Petroleum ether extracts of the roots of three plants viz. Derris elliptica, Linostoma decandrum and Croton tiglium were found to have remarkable larvicidal activity; D. elliptica extract was the most effective and with LC50 value of 0.307 μg/ml its activity was superior to propoxur, the standard synthetic larvicide. Half-life of larvicidal activity of D. elliptica and L. decandrum extracts ranged from 2-4 days.

Plant physiological and soil characteristics associated with methane and nitrous oxide emission from rice paddy

Methane (CH4) and nitrous oxide (N2O) are important greenhouse gases causing global warming and climate change. Efforts were made to analyze the CH4 and N2O flux in relation to plant and soil factors from rice (Oryza sativa L.) paddy. Ten popularly grown rice varieties namely Rashmisali, Bogajoha, Basmuthi, Lalkalamdani, Choimora (traditional varieties); Mahsuri, Moniram, Kushal, Gitesh and Profulla (high yielding varieties = HYV) were grown during monsoon season of July 2006. The CH4 and N2O emissions were measured the date of transplanting onwards at weekly interval along with soil and plant parameters. The seasonal integrated CH4 and N2O emission (Esif) from rice ranged from 8.13 g m(-2) to 13.00 g m(-2) and 121.63 mg N2O-N m(-2) to 189.46 mg N2O-N m(-2), respectively. Variety Gitesh emitted less N2O and CH4 amongst all the rice varieties. Both CH4 and N2O emission exhibited a significant positive correlation with leaf area, leaf number, tiller number and root dry weight. Soil organic carbon of the experimental field was associated with both CH4 and N2O emission whereas nitrate-N content of soil was associated with N2O emission. Methane emission showed significant positive correlations with soil temperature and crop photosynthetic rate. Traditional rice varieties with profuse vegetative growth recorded higher CH4 and N2O fluxes compared to HYVs. Gitesh and Kushal having low seasonal CH4 and N2O emission with higher yield potential can be recommended as low greenhouse gas emitting rice varieties.

Evaluation of PermaNet 2.0 mosquito bednets against mosquitoes, including Anopheles minimus s.l., in India

Wash resistance and field bioefficacy of PermaNet 2.0 nets, long lasting insecticidal nets, against mosquitoes were evaluated in Assam, northeastern India. After repeated hand washings at 12-day intervals a decline in the mosquito killing ability of PermaNet nets was noted (trend chi2 38.9, p < 0.0001), yet these nets retained good insecticidal efficacy for up to 15 wash cycles, producing a 72.5% mean mortality of An. minimus 24 hours after a 3-minute exposure in World Health Organization cones after 15 washings. Significantly fewer (p < 0.001) mosquitoes were captured in self-baited landing collections in houses equipped with PermaNet nets than in houses using untreated nets in the case of culicines (p < 0.001) but not with anophelines, including An. minimus. The use of PermaNet nets resulted in noticeably fewer bites from Culex pseudovishnui (68.5%) and Cx. quinquefasciatus (70%). Blood-feeding inhibition of mosquitoes in deliberately torn PermaNet nets was seen, indicating a protective effect for those sleeping under these nets. No serious adverse effects of the PermaNet nets were reported by users.

Wild edible mushrooms of meghalaya

Different flesh mushrooms grow widely in Meghalaya. Altogether fie edible species were collected and identified which were found abundantly in forest and are known to be consumed by local people for time immemorial, The species identified are lentinus edodes (Berk) Sing., Boletus edulis Bull ex Fr., Clavaria cinerea (Fr.) Schroet, Clavaria aurea (F) Quet and cantharellus floccosus Juss.