RESUMO
The method of salt-assisted vapor-liquid-solid (VLS) growth is introduced to synthesize 1D nanostructures of trichalcogenide van der Waals (vdW) materials, exemplified by niobium trisulfide (NbS3). The method uses a unique catalyst consisting of an alloy of Au and an alkali metal halide (NaCl) to enable rapid and directional growth. High yields of two types of NbS3 1D nanostructures, nanowires and nanoribbons, each with sub-ten nanometer diameter, tens of micrometers length, and distinct 1D morphology and growth orientation are demonstrated. Strategies to control the location, size, and morphology of growth, and extend the growth method to synthesize other transition metal trichalcogenides, NbSe3 and TiS3, as nanowires are demonstrated. Finally, the role of the Au-NaCl alloy catalyst in guiding VLS synthesis is described and the growth mechanism based on the relationships measured between structure (growth orientation, morphology, and dimensions) and growth conditions (catalyst volume and growth time) is discussed. These results introduce opportunities to expand the library of emerging 1D vdW materials to make use of their unique properties through controlled growth at nanoscale dimensions.
RESUMO
Low soil moisture during dry season, poor soil properties and lack of adequate crop varieties are the major constraints for sustainable intensification of eastern Himalayas in changing climate. Suitable varieties, tillage alteration and integrated nutrient management with emphasis on locally available crop residues/plant biomass may help addressing these issues. The role of minimum tillage (MT) and no-till (NT), and organic matter substitution on conferring of favourable root environment, improvement in morpho-physiology and subsequent productivity of the crops are not objectively studied in Himalayan ecosystems. Thus, a six year field study was conducted for examining the residual effect of tillage and nutrient management (NM) practices applied to summer (rainy) rice (Oryza sativa L) on root growth-attributes and impact on morpho-physiology of succeeding winter pea (Pisums ativum L.) grown uniformly under NT. Higher root surface area, total root length, root volume, root length ratio (RLR) and root tissue densityin pea crop were observed under residual effect of conventional tillage (CT) relative to NT and MT. In addition, significantly higher values of functional root traits viz., root length ratio (RLR), root mass ratio and root finenessin pea were observed under CT and application of 50% NPK and 100% NPK relative to other tillage and NM practices. However, increased root exudation was observed under NT and MTalong with organic residue addition. Noticeable changes in stress responsive morpho-physiological traits like enhanced chlorophyll pigmentation and favourable leaf characteristics were observed in pea crop grown under NT with 50% NPK+weed biomass (WB)/green leaf manure (GLM) applications. Higher leaf area expansion and thickness were recorded with optimum turgidity under NT and MT than that under CT. Comparative increase in green pod and stover yield of pea with enhanced partition efficiency and harvest index were recorded under MT/NT along with 50% NPK+WB/GLM application than that under CT and other NM practices. Thus, adoption of MT/NT along with 50% NPK+WB/GLM in summer rice is recommended for inducing favourable root environment and optimised pea production in succeeding winter season in study region of the Eastern Himalayas, India and other similar agro-ecosystems.