The organic–inorganic hybrid nanocomposites comprising of poly(iminohexamethyleneiminoadipoyl), better known as Polyamide-6,6 (abbreviated henceforth as PA66), and silica (SiO
2) were synthesized ...through sol–gel technique at ambient temperature. The inorganic phase was generated in situ by hydrolysis–condensation of tetraethoxysilane (TEOS) in different concentrations, under acid catalysis, in presence of the organic phase, PA66, dissolved in formic acid. Infrared (IR) spectroscopy was used to monitor the microstructural evolution of the silica phase in the PA66 matrix. Wide angle X-ray scattering (WAXS) studies showed that the crystallinity in PA66 phase decreased with increasing silica content. Atomic force microscopy (AFM) of the nanocomposite films revealed the dispersion of SiO
2 particle with dimensions of <100
nm in the form of network as well as linear structure. X-ray silicon mapping further confirmed the homogeneous dispersion of the silica phase in the bulk of the organic phase. The melting peak temperatures slightly decreased compared to neat PA66, while an improvement in thermal stability by about 20
°C was achieved with hybrid nanocomposite films, as indicated by thermogravimetric analysis (TGA). Dynamic mechanical analysis (DMA) exhibited significant improvement in storage modulus (
E′) for the hybrid nanocomposites over the control specimen. An increase in Young's modulus and tensile strength of the hybrid films was also observed with an increase in silica content, indicating significant reinforcement of the matrix in the presence of nanoparticles. Some properties of the in situ prepared PA66-silica nanocomposites were compared with those of conventional composites prepared using precipitated silica as the filler by solution casting from formic acid.
•APSIM was evaluated using an Asian dataset covering 12 countries, numerous soils, crops, and practices.•Assessment was from both crop and soil simulation perspectives, including sequence ...effects.•The model performed well in simulating the diversity of cropping systems to which it was applied.•Input parameter estimation challenges, some indicating possible model deficiencies, were noted.•Desirable future APSIM improvements were identified.
Resource shortages, driven by climatic, institutional and social changes in many regions of Asia, combined with growing imperatives to increase food production whilst ensuring environmental sustainability, are driving research into modified agricultural practices. Well-tested cropping systems models that capture interactions between soil water and nutrient dynamics, crop growth, climate and farmer management can assist in the evaluation of such new agricultural practices. One such cropping systems model is the Agricultural Production Systems Simulator (APSIM). We evaluated APSIM’s ability to simulate the performance of cropping systems in Asia from several perspectives: crop phenology, production, water use, soil dynamics (water and organic carbon) and crop CO2 response, as well as its ability to simulate cropping sequences without reset of soil variables. The evaluation was conducted over a diverse range of environments (12 countries, numerous soils), crops and management practices throughout the region. APSIM’s performance was statistically assessed against assembled replicated experimental datasets. Once properly parameterised, the model performed well in simulating the diversity of cropping systems to which it was applied with RMSEs generally less than observed experimental standard deviations (indicating robust model performance), and with particular strength in simulation of multi-crop sequences. Input parameter estimation challenges were encountered, and although ‘work-arounds’ were developed and described, in some cases these actually represent model deficiencies which need to be addressed. Desirable future improvements have been identified to better position APSIM as a useful tool for Asian cropping systems research into the future. These include aspects related to harsh environments (high temperatures, diffuse light conditions, salinity, and submergence), conservation agriculture, greenhouse gas emissions, as well as aspects more specific to Southern Asia and low input systems (such as deficiencies in soil micro-nutrients).
•We evaluated options for increasing Boro rice production at Satkhira, Bangladesh.•Earlier sowing offers higher grain yields with increased cropping area due to better utilisation of fresh river ...water.•Increases in Boro rice production of up to 4x are possible.•Constraints with late-maturing monsoon rice crops and ineffective sluice gate management must be solved.•Potential problems associated with increased salinization of polder soils need to be investigated.
Increasing Boro (irrigated dry season) rice production in the saline coastal zone (CZ) is part of the Bangladesh Government strategy for meeting its Sustainable Development Goals (SDG’s). However salinity and fresh water shortages during the Rabi (dry) season result in large areas of land remaining uncropped and under-utilised in the CZ, with crop yields below potential. We evaluated a range of options for increasing Boro rice production and farmer profit in this region. These included changes to sowing dates in combination with different polder sluice-gate management strategies aimed at increasing irrigation water supply and cropping area. We employed a case-study approach, using a combination of field experimentation, APSIM cropping systems modelling, and economic analysis, focussing on Satkhira District, Khulna Division. We found the most profitable strategies were to establish Boro rice crops in mid-November, around a month earlier than current farmer practice, on larger portions of land irrigated using river water supplied via the polder canal network. This offers significant increases in both farmer profit and regional production (up to 4x). The reasons for the gains are dual – (1) potential rice yields are higher; and (2) early sowing unleashes the potential of extensive fresh-water availability to greatly increase cropping area, because at that time river salinity levels are low and unlimited amounts of suitable irrigation water are available. Under current practices with later sowing dates (around mid-December), these early-season water resources are hardly used. To achieve the advantages of early-sowing, certain system changes are necessary. Firstly, farmers must adopt early-maturing transplanted Aman (T. Aman) rice cultivars in the monsoon season. Secondly, they must synchronise agronomic timings with fellow farmers in polder sluice-gate management zones to allow efficient gate operation and timely drainage of stagnant monsoon waters from fields in October, followed by early-season establishment of Boro rice crops. The applicability of our findings will vary geographically in the CZ, as a function of prevailing dynamics of river salinity, water tables, soils and climate. To understand the economics at a national scale, our analysis should be extended on a regional basis to estimate regional production gains possible, as well as to assess environmental health risks – particularly related to increased salinization of polder soils. Our analysis suggests that substantial investment in further research and achieving the required social and agronomic changes may be warranted.
In this paper, case wise studies have been made to investigate the possibility of propagation of Rayleigh-type wave in a composite structure comprised of two transversely-isotropic material layers ...with viscoelastic effect. The common interface between the layers is considered to be rigid whereas the base has been considered as rigid, stress-free and yielding in three different cases (Case-I, II and III). Closed-form of frequency equation and damped velocity equation has been established analytically for propagation of Rayleigh-type wave in a composite structure for all three cases. In special cases, frequency equations and damped velocity equations for the case of composite structure with rigid, stress-free and yielding base have been found in well-agreement to the established standard results pre-existing in the literature. Numerical and graphical computation of phase and damped velocity of Rayleigh-type wave propagating in the composite structure comprised of double transversely-isotropic viscoelastic Taylor sandstone material layers (Model-I) and double isotropic viscoelastic material layers (Model-II) have been carried out. Significant effect of anisotropy and width ratio of layers, dilatational and volume viscoelasticity associated with viscoelasticity of layer medium and yielding parameter associated with yielding base of composite structure on phase and damped velocities of Rayleigh-type wave for the considered models have been traced out. The comparative study has been performed to unravel the effect of viscoelasticity over elasticity and anisotropy over isotropy in the present problem.
Recent technology has modeled VANET (vehicular adhoc network) communication well in terms of privileges to derive vehicular communication technologically to save time, energy, and money. Due to the ...increase in powerful technology in modern times, VANETs play a vital role in uplifting daily concerns across vehicles and vehicular identities. Hence, to tune VANETs to become compatible with traditional technologies and increase demand, VANETs require upgrading. The severity and frequency of unwanted occurrences have become a considerable concern for our day-to-day lives relating to vehicular position. Thus, verily updated methodologies or working procedures are needed for the future VANET interplay to eradicate such problems occurring through vehicular identities. This article outlines in technology related to VANETS, future developments, and coping issues by deriving comprehensive frameworks, workflow patterns, upgrading procedures including big data, fog computing, SDN (software defined networking), and SIoT (social Internet of Things). This article provides a high-level overview of a complete VANET upgrade solution to address future problem management issues under a range of acceptable scientific themes, indicators, and combinations.
► The evolution of granitoids during the growth of NW part of eastern Dharwar craton is elucidated. ► Subduction-related accretion followed by slab break-off was the main process of crust formation. ...► Initially slab melting enriched the overlying mantle wedge as well as produced TTG-like rocks. ► Then sanukitoid-like porphyritic granodiorites were produced from the enriched mantle wedge. ► Intrusion of these granodiorites triggered melting of crust producing biotite monzogranites.
Geochemical and Nd isotope data on granitoids of the NW part of the late Archaean eastern Dharwar craton are presented to elucidate their petrogenesis and role in crust formation. The granitoids are divided into three suites viz. trondhjemite–granodiorite gneisses, biotite monzogranites and porphyritic biotite granodiorites. The gneisses are pre- to syn-kinematic (with respect to deformation in the adjacent Hungund–Kushtagi schist belt), which show variable SiO
2 and Al
2O
3, enriched LREE and depleted HREE with slightly negative to no Eu anomalies. They display unusual chemistry in having higher FeO(T), K
2O, Ba, Cr and Ni compared to the typical Archaean tonalite–trondhjemite–granodiorite (TTG). The biotite monzogranites are mostly syn- to late-kinematic and exhibit evolved calc-alkaline compositions with high SiO
2, K
2O, LILE and LREE, depleted to undepleted HREE and strongly negative to no Eu anomalies. The porphyritic granodiorites show syn- to late-kinematic calc-alkaline, sanukitoid-like character with a wide range of SiO
2, higher TiO
2, P
2O
5, Sr, Ba, Cr and Ni, and lower Rb. They, however, uniquely display higher K
2O, ΣREE and Th than typical sanukitoids. The trondhjemite–granodiorite gneisses are interpreted as product of melting of a subducted basaltic slab followed by slight contamination from the overlying metasomatized mantle wedge. Subsequent melting of the extremely metasomatized mantle wedge resulted in formation of the parental magma of the porphyritic granodiorites. Intrusion of the latter triggered melting of the TTG crust accreted earlier and generated the evolved monzogranites. The monzogranites occurring east of the Hungund–Kushtagi schist belt show higher εNd but lower
T
DM ages than those occurring to the west, indicating that terranes with different histories were juxtaposed by lateral accretion.
Electron beam irradiation of poly(iminohexamethylene-iminoadipoyl) (polyamide-6,6) (PA66) films prepared by compression molding was carried out over a range of irradiation doses (20-500kGy) in air. ...The crystallinity variations were studied using infrared (IR) spectroscopy and wide angle X-ray scattering (WAXS). Gel content of the irradiated films was measured. G(S)/G(X) ratio for the irradiated films was found out from Charlesby-Pinner plot. It was seen that the reduction of crystallinity was drastic initially, which was less in the range 200-500kGy. The 934 and 1202cm-1 bands were used to follow the crystallinity trends in the PA66 films. The presence of both alpha and gamma phase was seen in all the PA66 films at room temperature. The gel content was observed in the films receiving a dose of 200 and 500kGy. No gel was found in the films below 200kGy. The G(S)/G(X) value was found out to be 3.34, which suggests more of chain scission over crosslinking.
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