X-ray absorption spectroscopy systematics at the tungsten L-edge

A series of mononuclear six-coordinate tungsten compounds spanning formal oxidation states from 0 to +VI, largely in a ligand environment of inert chloride and/or phosphine, has been interrogated by tungsten L-edge X-ray absorption spectroscopy. The L-edge spectra of this compound set, comprised of [W<sup>0</sup>(PMe<sub>3</sub>)<sub>6</sub>], [W<sup>II</sup>Cl<sub>2</sub>(PMePh<sub>2</sub>)<sub>4</sub>], [W<sup>III</sup>Cl<sub>2</sub>(dppe)<sub>2</sub>][PF<sub>6</sub>] (dppe = 1,2-bis(diphenylphosphino)ethane), [W<sup>IV</sup>Cl<sub>4</sub>(PMePh<sub>2</sub>)<sub>2</sub>], [W<sup>V</sup>(NPh)Cl<sub>3</sub>(PMe<sub>3</sub>)<sub>2</sub>], and [W<sup>VI</sup>Cl<sub>6</sub>] correlate with formal oxidation state and have usefulness as references for the interpretation of the L-edge spectra of tungsten compounds with redox-active ligands and ambiguous electronic structure descriptions. The utility of these spectra arises from the combined correlation of the estimated branching ratio (EBR) of the L<sub>3,2</sub>-edges and the L<sub>1</sub> rising-edge energy with metal Z<sub>eff</sub>, thereby permitting an assessment of effective metal oxidation state. An application of these reference spectra is illustrated by their use as backdrop for the L-edge X-ray absorption spectra of [W<sup>IV</sup>(mdt)<sub>2</sub>(CO)<sub>2</sub>] and [W<sup>IV</sup>(mdt)<sub>2</sub>(CN)<sub>2</sub>]<sup>2–</sup> (mdt<sup>2–</sup> = 1,2-dimethylethene-1,2-dithiolate), which shows that both compounds are effectively W<sup>IV</sup> species. Use of metal L-edge XAS to assess a compound of uncertain formulation requires: 1) Placement of that data within the context of spectra offered by unambiguous calibrant compounds, preferably with the same coordination number and similar metal ligand distances. Such spectra assist in defining upper and/or lower limits for metal Z<sub>eff</sub> in the species of interest; 2) Evaluation of that data in conjunction with information from other physical methods, especially ligand K-edge XAS; 3) Increased care in interpretation if strong π-acceptor ligands, particularly CO, or π-donor ligands are present. The electron-withdrawing/donating nature of these ligand types, combined with relatively short metal-ligand distances, exaggerate the difference between formal oxidation state and metal Z<sub>eff</sub> or, as in the case of [W<sup>IV</sup>(mdt)<sub>2</sub>(CO)<sub>2</sub>], add other subtlety by modulating the redox level of other ligands in the coordination sphere

Li1.5La1.5MO6 (M = W6+, Te6+) as a new series of lithium-rich double perovskites for all-solid-state lithium-ion batteries

Solid-state batteries are a proposed route to safely achieving high energy densities, yet this architecture faces challenges arising from interfacial issues between the electrode and solid electrolyte. Here we develop a novel family of double perovskites, Li1.5La1.5MO6 (M = W6+, Te6+), where an uncommon lithium-ion distribution enables macroscopic ion diffusion and tailored design of the composition allows us to switch functionality to either a negative electrode or a solid electrolyte. Introduction of tungsten allows reversible lithium-ion intercalation below 1 V, enabling application as an anode (initial specific capacity >200 mAh g-1 with remarkably low volume change of ∼0.2%). By contrast, substitution of tungsten with tellurium induces redox stability, directing the functionality of the perovskite towards a solid-state electrolyte with electrochemical stability up to 5 V and a low activation energy barrier (<0.2 eV) for microscopic lithium-ion diffusion. Characterisation across multiple length- and time-scales allows interrogation of the structure-property relationships in these materials and preliminary examination of a solid-state cell employing both compositions suggests lattice-matching avenues show promise for all-solid-state batteries

Evaluation of a Small Scale Teak Plantation Managed under the Participatory Forestry Programme

Teak (Tectona grandis) was introduced to Sri Lanka in 1680 by Dutch. Since then teak was grown mainly as monocultures and as a mix with Jak, Margosa, Eucalypts and Mahogany. The popular methods of establishing teak plantations were Taungya System and Participatory Forestry Programmes (PFPs) so that the Forest Department can share the benefits with local people. Therefore, this paper evaluates the growth and financial benefits of a teak plantation managed under PFP.A 12.5 ha teak land was selected from Rambapokuna village in Kurunegala district for the data collection. It was partitioned into 0.4 ha blocks and given to the farmers under 25 year lease agreement in 1999. As the entire plantation is homogeneous, one block in this land was randomly selected and a transect was demarcated along the diagonal. 0.02 circular plots were then demarcated at 5m intervals to collect data. Breast height diameter (dbh) and total height of all the trees were measured (42 stems) and the tree basal area and volume were calculated using standard methods.The results revealed a poor growth of teak (Class III) when compared with the Provisional Yield Tables. The average tree dbh, height and volume values were 11.2cm, 8.8m and 0.051m3 respectively. Pre-commercial thinning has been done in 2007 without a scientific study.In order to calculate the income and cost by time series analysis, the current volume was projected using the Class III yield table. The estimated volume in 2049 including the thinnings is 48.895m3 with the predicted income of USD 28,584 (assuming 75% timber recovery in harvesting) for the 0.4 ha block. Total extraction and replanting cost was estimated as USD 5,874. The Net Present Value of the total income and cost will be Rs USD 1,501 assuming the present discount rate as 10%.The reason of poor growth rate is due to the site quality and lack of proper silvicultural practices. Therefore, it is recommended to apply proper management practices to obtain a higher volume which can generate a higher profit

Transboundary movements of foot-and-mouth disease from India to Sri Lanka: A common pattern is shared by serotypes O and C.

Foot-and-mouth disease (FMD) affects the livestock industry in a transboundary manner. It is essential to understand the FMD phylodynamics to assist in the disease-eradication. FMD critically affects the Sri Lankan cattle industry causing substantial economic losses. Even though many studies have covered the serotyping and genotyping of FMD virus (FMDV) in Sri Lanka, there is a significant knowledge gap exists in understanding the FMDV phylodynamics in the country. In the present study, the VP1 genomic region of FMD viral isolates belonging to serotype C from Sri Lanka and other South Asian countries were sequenced. All the published VPI sequences of serotype C and most of the published VP1 sequences for lineage ME-SA/Ind-2001d of serotype O from Sri Lanka, India, and other South Asian countries were retrieved. The datasets of serotype C and serotype O were separately analyzed using Bayesian, maximum likelihood, and phylogenetic networking methods to infer the transboundary movements and evolutionary aspects of the FMDV incursions in Sri Lanka. A model-based approach was used to detect any possible recombination events of FMDV incursions. Our results revealed that the invasions of the topotype ASIA of serotype C and the lineage ME-SA/Ind-2001d have a similar pattern of transboundary movement and evolution. The haplotype networks and phylogenies developed in the present study confirmed that FMDV incursions in Sri Lanka mainly originate from the Indian subcontinent, remain quiet after migration, and then cause outbreaks in a subsequent year. Since there are no recombination events detected among the different viral strains across serotypes and topotypes, we can assume that the incursions tend to show the independent evolution compared to the ancestral viral populations. Thus, we highlight the need for thorough surveillance of cattle/ruminants and associated product-movement into Sri Lanka from other regions to prevent the transboundary movement of FMDV

Analyses of phylogenetics, starch granule morphology and consumer preference of <i>Canna indica</i> L. grown in Sri Lanka

Canna indica is a tuber crop which has many medicinal values. In Sri Lanka, C. indica tubers are consumed in rural areas and mainly available in street-markets of Nuwara-Eliya and Kandy Districts. In the present study, we assessed the phylogenetics of C. indica, starch granule morphology and consumer preference of C. indica tubers in comparison to the popular tuber crops. The phylogenetic analysis was conducted based on the sequence polymorphism at rbcL, atpB gene, trnL-trnF and trnH-psbA marker-loci with respect to the ornamental Canna spp. in Sri Lanka and the previously published sequences of Canna spp. The starch granules were isolated and observed under optical and scanning electron microscopes. The diameter and the surface area of the starch granules were measured under the optical microscope and subjected to analysis of variance. As C. indica tubers are consumed as boiled tuber pieces in Sri Lanka, the consumer preference analysis was conducted using the boiled tuber pieces C. indica, Xanthosoma sagittifolium, Manihot esculenta, Solanum tuberosum, and Ipomoea batatas. The phylogenetic tree based on rbcL marker revealed that C. indica in Sri Lanka is slightly divergent from the other Canna spp. Only the polymorphism of the atpB gene can be used to differentiate C. indica from the ornamental Canna sp. in Sri Lanka. The morphological analysis of starch granules revealed that C. indica has the biggest scallop-seashell shaped starch granules compared to other tuber species. The boiled C. indica tubers were accepted better than that of X. sagittifolium, rated equally to the tubers of S. tuberosum and M. esculenta, and rated less than I. batatas. The hardy and fibrous nature of C. indica tubers must be the major limiting factors for achieving the highest consumer preference highlighting the need of breeding for better texture in tuber

Microzonation, ecological risk and attributes of metals in highway road dust traversing through the Kaziranga National Park, Northeast India: implication for confining metal pollution in the national forest

Despite the abundant literature on metal contamination through road dust (RD) in urban/suburban and residential/highway regions, the RD of highways traversing through the Kaziranga National Park, NE India, has not been studied and lacks baseline data. The objective of the present study was to ascertain the possibility of highway microzonation based on temporal and spatial variability of metal pollution level and ecological risk. It was found that the RD contains an average content of (1.7�33.5 mg/kg) for Cd, Co, Cu and Pb and (121�574 mg/kg) for Ni, Zn, Cr and Mn across the highway passing through the national forest attributed by various sources. The study revealed three possible microzones present in the studied highway NH-37 based on spatial trend of metal as well as human interference. An attempt was made to understand the possible source of metals by principal component analysis, and four sources were identified: Three were of vehicular origin, and another was related to road surface and subsurface condition. The use of noise barrier walls as an effective measure to control the translocation of RD from one place to other was recommended to reduce the hostile effects of metal accumulation in the sensitive ecosystem. Thus, the study suggested and necessitated micronizing the system based on human interference level, ecological risk factors, spatial variability of pollutants and traffic pattern for their efficient management and conservation.by Upasona Devi, Kaling Taki, Tanya Shukla, Kali P. Sarma, Raza R. Hoque and Manish Kuma