The field of nanoscience and nanotechnology is extending the applications of physics, chemistry, biology, engineering and technology into previously unapproached infinitesimal length scales. The ...polymer–nanoparticles/nanocomposites have been the exponentially growing field of research for developing the materials in last few decades and have been mainly focusing on the structure–property relationships and their development. Since the polymer–nanocomposites have been the staple of modern polymer industry, their durability under various environmental conditions and degradability after their service life are also essential fields of research. Thus, this article is intended to review the status of worldwide research in this aspect. Among various nanoparticulates, clay minerals and carbon nanotubes are more often used in enhancing physical, mechanical and thermal properties of polymers. In very few systems, the nanoparticulates have been incorporated into polymer as ‘
nano-additives’ for both purposes: degradation and stabilization of polymers. The degradation and durability of polymers is reviewed in the presence of nanoparticles/nanocomposites under different environmental conditions. Nanoparticle-induced biodegradation of polymers is also discussed.
Abstract
The intercropping of legumes with cereals help to achieve sustainable intensification by their mutual complementarity at efficiently using radiation, nutrients, etc. Several studies ...indicated such beneficial effects on the other component crop however, little research has been conducted to quantify their effects on the subsequent crop in a cropping system. In this study, the effect of the legume intercropping on the entire cropping system, particularly the maize + legume-wheat system was studied. Four legumes intercropped to maize followed by wheat crop were studied for intensification measures such as wheat equivalent yield (WEY), land equivalent ratio (LER), sustainable value index (SVI), and economic returns. N saving effect of legumes on the subsequent wheat crop was quantified with two N levels. Maize + cowpea-wheat combination was the most productive and economic intercrop combination (LER = 1.71, SVI = 0.96) with an increase in net economic return (43.63%) with a B:C ratio of 1.94. An additional 25% N (37.5 kg ha
−1
) was saved in the wheat crop when the legume intercropping was undertaken with maize. The results suggest that intercropping is the key to diversification and reduces the risk of crop failures by enhancing land-use efficiency, soil fertility, and economic returns under weather vagaries. This will be beneficial to small and marginal farmers of many countries.
Previously synthesized novel chalcone oxime ethers (COEs) were evaluated for inhibitory activities against monoamine oxidases (MAOs) and acetylcholinesterase (AChE). Twenty-two of the 24 COEs ...synthesized, except
and
, had potent and/or significant selective inhibitory effects on MAO-B.
potently inhibited MAO-B with an IC
value of 0.018 µM, which was 105, 2.3, and 1.1 times more potent than clorgyline, lazabemide, and pargyline (reference drugs), respectively.
, and
were also active against MAO-B, both had an IC
value of 0.028 µM, which was 67 and 1.5 times lower than those of clorgyline and lazabemide, respectively. Most of the COEs exhibited weak inhibitory effects on MAO-A and AChE.
most potently inhibited MAO-A (IC
= 0.88 µM) and also significantly inhibited MAO-B (IC
= 0.13 µM), and it could be considered as a potential nonselective MAO inhibitor.
and
inhibited AChE with IC
values of 5.35 and 4.39 µM, respectively. The selectivity index (SI) of
for MAO-B was higher than that of
(SI = 778.6 vs. 222.2), but the IC
value (0.028 µM) was slightly lower than that of
(0.018 µM). In reversibility experiments, inhibitions of MAO-B by
and
were recovered to the levels of reference reversible inhibitors and both competitively inhibited MAO-B, with K
values of 0.0075 and 0.010 µM, respectively. Our results show that
and
are potent, selective MAO-B inhibitors, and
is a candidate of dual-targeting molecule for MAO-B and AChE.
Graphene nanoscrolls (GNS), one‐dimensional carbon‐based nanomaterials, have been predicted to possess extraordinary characteristics due to their unique open topology with scrolled graphene ...monolayers. In this study, the conversion of planar 2‐D graphene nanoplatelets (GNPs) to tubular and scrolled 1‐D GNSs is described. The effects of GNS as a nucleating agent to modulate the morphology, crystallization, and nano‐mechanical properties of polylactic acid (PLA) were studied. The nucleating effect of GNS and its unique topological characteristics proves to influence the crystallization of PLA. Fourier transform infrared (FTIR) spectroscopy indicated nonpreferential interactions of PLA chains around GNS due to the bulky and helical PLA macromolecular chains. Superior interfacial interactions and strain in GNS provide better load transfer between GNS and PLA matrices, resulting in higher modulus and hardness. This study is the first detailed analysis to elucidate the role of unique GNS to favorably modulate the properties of a polymer.
In the present study, the composite films have been prepared from the aqueous dispersions of starch with microcrystalline cellulose using glycerol as plasticizer and irradiated under ultraviolet (UV) ...light using sodium benzoate as photo-sensitizer. Photo-crosslinking was characterized by measuring the water absorption under 100% relative humidity, swelling degree and gel fraction in dimethylsulphoxide (DMSO), upon irradiation time. Both, the incorporation of cellulose and photo-irradiation were found to decrease the water absorption, swelling in DMSO and increase the gel fraction. Thermal transitions indicated the anti-plasticization of amylopectin chains at the fiber/matrix interface. With increasing content of cellulose and photo-irradiation time, the tensile modulus and strength were found to improve. It is summarized that the combination of cellulose reinforcement and photo-crosslinking of matrix has improved the physical and mechanical properties.
Summary
The traditional aerosol‐forming composites are a mixture of potassium nitrate/chlorate and synthetic resins like phenol‐formaldehyde, melamine‐formaldehyde, polyurethane, and epoxy resin. ...Though these synthetic organic resins have excellent adhesion and mechanical properties, their high flammability and associated life‐threatening occupational hazard have limited their application. Such compositions' combustion flame may reach up to 2100°C and cause secondary fire risk in an explosive atmosphere, especially ship engine rooms and oil‐producing platforms. This study aimed to investigate the ability of natural flame‐retardant tannic acid, which is a natural phenolic compound abundant in many plants, to reduce the exothermicity of potassium nitrate/chlorate‐based pyrotechnic composite. In the present work, we newly developed a pyrotechnic composition that employed tannic acid as a reducer instead of synthetic resin. Its combustion behaviour, thermal properties, and fire extinguishing performance were comparatively evaluated against phenolic resin‐based traditional pyrotechnic composition. Though both the new and traditional pyrotechnic composition has shown similar fire extinguishing efficacy, the newly developed composition showed 57% lower combustion flame temperature, faster burn rate, and lower calorific value than the traditional composition. The physical and chemical characteristics of the discharged aerosol were characterized by a series of techniques viz; high‐resolution X‐ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and energy dispersive X‐ray analysis to understand the fire extinguishing mechanism.
Abstract
Pyrotechnic‐based firefighting systems have been found to be effective in a wide variety of firefighting applications. Binders in pyrotechnic mixtures play a significant role as they ...consolidate the ingredients, provide excellent mechanical strength and increase the storage life. The rise in health and environmental safety concerns in recent years has directed our research towards natural binder systems of biological origins. Therefore, in this work, galactomannan, also called guar gum, was comparatively investigated against four different types of conventional binders, phenol–formaldehyde resin, ethyl cellulose, hydroxyethyl cellulose and carboxymethyl cellulose sodium salt, which are being used in aerosol‐forming pyrotechnic mixtures for firefighting application. It was found that the nature of the binder in an amount of 3% by weight significantly influences the combustion behaviour, fire suppression performance, mechanical and thermal characteristics of gallic acid–KNO
3
–KClO
3
tertiary aerosol‐forming pyrotechnic mixture for fire fighting application. The safety and performance characteristics of these formulations were evaluated by conducting analyses specific to pyrotechnic formulations, that is, burn rate measurement, heat of combustion, TGA/DSC thermal analysis, hygroscopic study, compression test and
n
‐heptane pool fire suppression test. It can be inferred from the values obtained from these analyses that guar gum is a preferred binder to the other four‐binder systems for the gallic acid–KNO
3
–KClO
3
pyrotechnic mixture.
Chitosan‐functionalized graphene oxides (FGOCs) were successfully synthesized. FGOCs were found to significantly improve the solubility of the GO in aqueous acidic media. The presence of organic ...groups was confirmed by means of XPS and TGA. Restoration of the sp2 carbon network and exfoliation of graphene sheets were confirmed by Raman spectroscopy, UV‐visible spectroscopy and WAXD. The SEM and AFM investigations of the resultant FGOCs showed that most of the graphene sheets were individual and few were layered. Controlled release behavior of Ibuprofen and 5‐fluorouracil was then investigated. We found that FGOCs are a promising new material for biological and medical applications.
GO is successfully functionalized with chitosan. The excellent exfoliation and dispersion of functionalized graphene sheets in aqueous acetic acid solution are presented. Moreover, IBU and 5‐FU are loaded successfully on FGOCs sheets, despite fewer π electrons. The controlled release behavior and long‐term biocompatibility of FGOCs graphene sheets suggest that they are promising novel materials for biomedical applications.
Monitoring of the vertical component of VLF electric fields is in progress at Chaumuhan, Mathura observatory (Lat. 27.5° N, Long. 77.68° E) at the frequency 3.012 kHz since 24 March 2011 employing ...the terrestrial antenna for studying the effect of electromagnetic radiations associated with earthquakes on the atmosphere. The bulk of the data collected for 8 months from February 2016 to October 2016 (except April 2016) have been analyzed in the light of shallow moderate earthquakes (4.9 ≤ M ≤ 6, depth ≤ 20 km) that have occurred in India and around within a radius of 1500 km assuming Mathura as a center. The VLF data obtained for each day is averaged out and its daily variation is compared with the monthly average for the group of eight months considered in the present analysis for identifying the disturbed days. It is found that daily variation exceeds the monthly mean, 1–23 days before the onset of the earthquakes in India and around within the radius of 1500 km. The influence of magnetic storms, lightning, local building noises, and seismic activities are studied on these VLF amplitude enhancements and it is found that they are not related to these spurious sources but are associated with the moderate seismic events that have occurred during the period of observations. Further, the generation and transmission mechanisms of these signals are also discussed.
A single method with a functionality switching option was developed for the first time for the Pd-catalyzed C-O cross-coupling of aryl bromides and bromo-chalcones with aldoximes. The ligand
t
...BuXPhos (
L2
) was found to be an effective supporting ligand for the Pd-catalyzed coupling of aldoximes with bromo coupling partners. The functionality switching from oxime ethers to a phenolic or hydroxy group was driven by solvent or temperature. This method offers the products in good to excellent yields in short reaction times.
A single method with a functionality switching option, to access oxime ethers and phenols, was developed for the first time for the Pd-catalyzed C-O cross-coupling of aryl bromides and bromo-chalcones with aldoximes.
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