Effect of age of plantation on seed characters and growth performance of Tokopatta (Livistona jinkensiana Griff.) seedling

Tokopatta palm (Livistona jinkensiana) is a valuable non timber multiple end uses forest species of Arunachal Pradesh. In order to establish improved plantation, the production of quality seedling of this species is essential. The present study was undertaken to determine tree age effects on seed characters, seed germination and performance of seedlings. The 500 seeds sample from each plantations aged 18, 25, 35, 45, 54, 63 and 74 years old around Pasighat town under East Siang district, Arunachal Pradesh, India were taken to see the effect of tree ageon seed morphological characters, seed germination and seedling performance. Significant variation was observed for seed diameter and seed weight between plantations of different ages. The age effect was also seen in the germination patterns with middle aged plantations producing most superior seeds in terms of seed morphological parameters and germination behavior. Seedling attributes after 12 months showed that seedling obtained from young and middle aged plantations (between 18 to 45 years) performed better than those beyond 50 years

Wild edible fruit tree resources of Arunachal Pradesh, North East India

The paper reports on the survey of wild edible fruit trees covering 49 sites from 17 districts of Arunachal Pradesh, India. A total of 52 wild edible fruits species representing 33 families was reported, out of which 10 had medicinal uses. The highest number of wild edible fruits belonged to family Moraceae (9 spp.) followed by Anacardiaceae (4 spp.) and Actinidiaceae (3 spp.). More than half the fruits (66.67%) are available during the monsoon season, i.e. between June and October. Dilenia indica, Castanopsis indica, Canarium strictum, Terminalia citrina, Phoebe cooperiana, Phyllanthus emblica and Artocarpus intergifolia are the commonly traded fruits. This is perhaps the only extensive survey which has so far been carried out on wild edible fruit tree resources covering all the districts of Arunachal Pradesh. In the present era where there is global interest on bioresource documentation, this study is significant for securing intellectual property right and preventing biopiracy

Plant species composition and product utility pattern of Garo homegardens in Meghalaya, India

Home garden is a traditional landuse system practiced by many rural households in the tropical region. The composition and management practices within homegardens are largely driven by cultural setup and ecological conditions. The present study characterized the plant species composition, utility patterns and management of  Garo homegardens in Dadenggre block, West Garo Hill district of Meghalaya, India. Fifty households from 5 villages were randomly selected and interviewed using a semi-structured questionnaire. The homegardens size ranged between 0.07 and 1.29ha, harbouring 132 plant species, out of which 74 species were trees, 19 shrubs and 39 herbs. Among the perennials, Areca catechu (areca nut) was the most common contributor to household earnings. When species were grouped into 9 utility classes (timber, medicinal, fruit, fuelwood, fodder, vegetables, ornamental, spice, and others), highest number was for fuelwood, followed by vegetables and fruits. The average household income was Rs. 318/100m2, the highest contribution from the sale of vegetables. Various home garden management activities were conducted, engaging family members and generating employment for others. Animal rearing is common in many households and the application of animal manure and household waste has helped maintain soil fertility of homegardens’ soils. Homegardens are integral to the Garo society, contributing significantly to household needs and activities.

Fracture Toughness of Fly Ash-Based Geopolymer Gels: Evaluations Using Nanoindentation Experiment and Molecular Dynamics Simulation

This paper presents the fracture toughness of sodium aluminosilicate hydrate (N-A-S-H) gel formed through alkaline activation of fly ash. While the fracture toughness of N-A-S-H is obtained experimentally from nanoindentation experiment implementing the principle of conservation of energy, the numerical investigation is performed via reactive force field molecular dynamics. A statistically significant number of indentations are performed on geopolymer paste yielding frequency distribution of Young’s modulus. Four distinct peaks are observed in the frequency distribution plot from which the peak corresponding to N-A-S-H was separated using statistical deconvolution technique. The young’s modulus of N-A-S-H, thus obtained from statistical deconvolution shows excellent match with the values reported in the literature, thus confirming successful identification of indentations corresponding to N-A-S-H. From the load-penetration depth responses of N-A-S-H, fracture toughness was obtained following the principle of conservation of energy. The experimental fracture toughness shows good correlation with the simulated fracture toughness of N-A-S-H, obtained from reactive force field molecular dynamics. The fracture toughness of N-A-S-H presented in this paper paves the way for multiscale simulation-based design of tougher geopolymer binders

Dynamics of confined water and its interplay with alkali cations in sodium aluminosilicate hydrate gel: insights from reactive force field molecular dynamics

This paper presents the dynamics of confined water and its interplay with alkali cations in disordered sodium aluminosilicate hydrate (N-A-S-H) gel using reactive force field molecular dynamics. N-A-S-H gel is the primary binding phase in geopolymers formed via alkaline activation of fly ash. Despite attractive mechanical properties, geopolymers suffer from durability issues, particularly the alkali leaching problem which has motivated this study. Here, the dynamics of confined water and the mobility of alkali cations in N-A-S-H is evaluated by obtaining the evolution of mean squared displacements and Van Hove correlation function. To evaluate the influence of the composition of N-A-S-H on the water dynamics and diffusion of alkali cations, atomistic structures of N-A-S-H with Si/Al ratio ranging from 1 to 3 are constructed. It is observed that the diffusion of confined water and sodium is significantly influenced by the Si/Al ratio. The confined water molecules in N-A-S-H exhibit a multistage dynamic behavior where they can be classified as mobile and immobile water molecules. While the mobility of water molecules gets progressively restricted with an increase in Si/Al ratio, the diffusion coefficient of sodium also decreases as the Si/Al ratio increases. The diffusion coefficient of water molecules in the N-A-S-H structure exhibits a lower value than those of the calcium-silicate-hydrate (C-S-H) structure. This is mainly due to the random disordered structure of N-A-S-H as compared to the layered C-S-H structure. To further evaluate the influence of water content in N-A-S-H, atomistic structures of N-A-S-H with water contents ranging from 5–20% are constructed. Qn distribution of the structures indicates significant depolymerization of N-A-S-H structure with increasing water content. Increased conversion of Si–O–Na network to Si–O–H and Na–OH components with an increase in water content helps explain the alkali-leaching issue in fly ash-based geopolymers observed macroscopically. Overall, the results in this study can be used as a starting point towards multiscale simulation-based design and development of durable geopolymers

Changes in genetic diversity parameters in unimproved and improved populations of teak (Tectona grandis L.f.) in Karnataka state, India

Teak (Tectona grandis L. f.; family Verbanaceae) is an important plantation tree species in the tropics and in India one of the first species to be prioritized for improvement. Improvement efforts for the last 50 years have essentially concentrated on augmenting quality seed production by establishing seed production areas (SPA) and clonal seed orchards (CSO). Presently, these two form the main sources of quality planting material for teak throughout the country. However, there is no information on the genetic quality of such sources nor information on the progeny used in plantation programmes. Reports of studies based on coniferous and tropical species provide conflicting results on the impact of domestication on the genetic diversity of populations (Chaisurisri and El Kassaby 1994; Rajora 1999; Moran et al. 2000; Godt et al. 2001; Icgen et al. 2006). Also the impact of domestication on the genetic diversity of progeny populations is poorly understood (Stoehr and El-Kassaby 1997; Schmitdtling and Hiplins 1998). Such studies become pertinent not only for gauging the impact of selection on reforestation stock, but also for effective genetic conservation of existing breeding populations. We therefore address two issues in the present study: (i) the change in genetic diversity with increasing levels of improvement, and (ii) the impact of the above change on genetic diversity of progeny populations

Influence of levels of genetic diversity on fruit quality in teak (Tectona grandis L.f.)

The study on the influence of genetic diversity on the fruit emptiness and seed germination (as a measure of fruit quality) of teak populations was carried out. The populations comprised three unimproved plantations, three seed-production areas and a clonal seed orchard within Karnataka. Significant variation between the populations was observed for fruit emptiness, seed germination and Jaccard’s dissimilarity index of the parent population. Genetic dissimilarity of populations was positively correlated to fruit emptiness and negatively correlated to seed germination. It is inferred that higher genetic dissimilarity of individuals within the population results in higher flower asynchrony and close-related mating, thereby leading to higher inbreeding depression manifested in the form of higher emptiness and low germination percentage

Fracture toughness of sodium aluminosilicate hydrate (NASH) gels: Insights from molecular dynamics simulations

This paper evaluates the fracture toughness of sodium aluminosilicate hydrate (N-A-S-H) gel formed through alkaline activation of fly ash via molecular dynamics (MD) simulations. The short- and medium-range order of the constructed N-A-S-H structures shows good correlation with the experimental observations, signifying the viability of the N-A-S-H structures. The simulated fracture toughness values of N-A-S-H (0.4–0.45 MPa m0.5) appear to be of the same order as the available experimental values for fly ash-based geopolymer mortars and concretes. These results suggest the efficacy of the MD simulation toward obtaining a realistic fracture toughness of N-A-S-H, which is otherwise very challenging to obtain experimentally, and no direct experimental fracture toughness values are yet available. To further assess the fracture behavior of N-A-S-H, the number of chemical bonds formed/broken during elongation and their relative sensitivity to crack growth are evaluated. Overall, the fracture toughness of N-A-S-H presented in this paper paves the way for a multiscale simulation-based design of tougher geopolymers

Elucidating the constitutive relationship of calcium–silicate–hydrate gel using high throughput reactive molecular simulations and machine learning

Prediction of material behavior using machine learning (ML) requires consistent, accurate, and, representative large data for training. However, such consistent and reliable experimental datasets are not always available for materials. To address this challenge, we synergistically integrate ML with high-throughput reactive molecular dynamics (MD) simulations to elucidate the constitutive relationship of calcium–silicate–hydrate (C–S–H) gel—the primary binding phase in concrete formed via the hydration of ordinary portland cement. Specifically, a highly consistent dataset on the nine elastic constants of more than 300 compositions of C–S–H gel is developed using high-throughput reactive simulations. From a comparative analysis of various ML algorithms including neural networks (NN) and Gaussian process (GP), we observe that NN provides excellent predictions. To interpret the predicted results from NN, we employ SHapley Additive exPlanations (SHAP), which reveals that the influence of silicate network on all the elastic constants of C–S–H is significantly higher than that of water and CaO content. Additionally, the water content is found to have a more prominent influence on the shear components than the normal components along the direction of the interlayer spaces within C–S–H. This result suggests that the in-plane elastic response is controlled by water molecules whereas the transverse response is mainly governed by the silicate network. Overall, by seamlessly integrating MD simulations with ML, this paper can be used as a starting point toward accelerated optimization of C–S–H nanostructures to design efficient cementitious binders with targeted properties

Elucidating the Costitutive Relationship of Calcium-Silicate-Hydrate Gel Using High Throughput Reactive Molecular Simulations and Machine Learning

Prediction of material behavior using machine learning (ML) requires consistent, accurate, and, representative large data for training. However, such consistent and reliable experimental datasets are not always available for materials. To address this challenge, we synergistically integrate ML with high-throughput reactive molecular dynamics (MD) simulations to elucidate the constitutive relationship of calcium–silicate–hydrate (C–S–H) gel—the primary binding phase in concrete formed via the hydration of ordinary Portland cement. Specifically, a highly consistent dataset on the nine elastic constants of more than 300 compositions of C–S–H gel is developed using high-throughput reactive simulations. From a comparative analysis of various ML algorithms including neural networks (NN) and Gaussian process (GP), we observe that NN provides excellent predictions. To interpret the predicted results from NN, we employ SHapley Additive exPlanations (SHAP), which reveals that the influence of silicate network on all the elastic constants of C–S–H is significantly higher than that of water and CaO content. Additionally, the water content is found to have a more prominent influence on the shear components than the normal components along the direction of the interlayer spaces within C–S–H. This result suggests that the in-plane elastic response is controlled by water molecules whereas the transverse response is mainly governed by the silicate network. Overall, by seamlessly integrating MD simulations with ML, this paper can be used as a starting point toward accelerated optimization of C–S–H nanostructures to design efficient cementitious binders with targeted properties