Chemical Composition and Antimicrobial Activity of Essential Oil from Seeds of Pimpinella heyneana

Chemistry of Natural Compounds -     

Potassium dihydrogen phosphate catalyzed one-pot synthesis of 2,4,5-triaryl-1H-imidazoles

<正>A simple and efficient method has been developed;benzil/benzoin undergoes smooth condensation with various substituted aldehyde and ammonium acetate in the presence of potassium dihydrogen phosphate(KH_2PO_4) under mild reaction conditions to afford the corresponding trisubstituted imidazole in excellent yields.The method for synthesis of product,the reaction mixture was reflux in ethanol for 40-90 min.The present method is simple,efficient,and cost-effective.     

Anisotropic Bulk Viscous Cosmological Models with?Variable G and Λ

This paper deals with Bianchi-I, Kantowski Sachs and Bianchi-III anisotropic cosmological models of the universe, filled with a bulk viscous cosmic fluid, in the presence of variable gravitational and cosmological constants. A new set of exact solutions of Einstein’s field equation have been obtained in both truncated and full causal theories. Physical behaviour of the models has also been discussed.     

Neutron ambient dose equivalent from 5 MeV/u 10,11B, 12,13C and 16,18O projectiles incident on a thick Al target

The neutron ambient dose equivalent has been measured from ¹⁰B, ¹¹B, ¹²C, ¹³C, ¹⁶O and ¹⁸O projectiles of energy 5 MeV/amu incident on a thick Al target at 0°, 30°, 60° and 90° with respect to the beam direction using a conventional dose equivalent meter. The calculated results obtained using previously reported empirical relations do not reproduce the experimental data. The results obtained from the PACE nuclear reaction code are closer to the experimental data as compared to the various empirical expressions. The ratio of the increase in the dose rates when the projectile is changed from the lighter to the heavier isotopes is fairly reproduced by most of the empirical formulations and the PACE code. A previously reported relation for the slope parameter is used to predict the directional distribution of the neutron dose for the projectiles used in this study. The calculated doses are lower than the experimental results in the forward directions but agree within the uncertainties at the backward directions. A new set of projectile-based parameters have been derived from the present experimental data which can be used in an empirical formulation.     

Self-aligned nanocrystalline ZnO hexagons by facile solid-state and co-precipitation route

In this study, we report the synthesis of well-aligned nanocrystalline hexagonal zinc oxide (ZnO) nanoparticles by facile solid-state and co-precipitation method. The co-precipitation reactions were performed using aqueous and ethylene glycol (EG) medium using zinc acetate and adipic acid to obtain zinc adipate and further decomposition at 450 °C to confer nanocrystalline ZnO hexagons. XRD shows the hexagonal wurtzite structure of the ZnO. Thermal study reveals complete formation of ZnO at 430 °C in case of solid-state method, whereas in case of co-precipitation method complete formation was observed at 400 °C. Field emission scanning electron microscope shows spherical morphology for ZnO synthesized by solid-state method. The aqueous-mediated ZnO by co-precipitation method shows rod-like morphology. These rods are formed via self assembling of spherical nanoparticles, however, uniformly dispersed spherical crystallites were seen in EG-mediated ZnO. Transmission electron microscope (TEM) investigations clearly show well aligned and highly crystalline transparent and thin hexagonal ZnO. The particle size was measured using TEM and was observed to be 50–60 nm in case of solid-state method and aqueous-mediated co-precipitation method, while 25–50 nm in case of EG-mediated co-precipitation method. UV absorption spectra showed sharp absorption peaks with a blue shift for EG-mediated ZnO, which demonstrate the mono-dispersed lower particle size. The band gap of the ZnO was observed to be 3.4 eV which is higher than the bulk, implies nanocrystalline nature of the ZnO. The photoluminescence studies clearly indicate the strong violet and weak blue emission in ZnO nanoparticles which is quite unique. The process investigated may be useful to synthesize other oxide semiconductors and transition metal oxides.     

The Effect of Zinc Ions on the Fluorescence Spectra of (Ln,Zn)of:Eu3+(Ln=Y,La and Gd) Powder Phosphors

This research note reports the fluorescence properties of Eu³⁺-doped in three sets of (Y-Zn, La-Zn and Gd-Zn) oxy fluoride powder phosphors. on excitation with a UV-source, these phosphors have displayed orangish-red color and for which the chromaticity coordinates ([Xbar], [Ybar] have been computed. the relative fluorescence intensity ratios (R) for the different measured emission transitions have been evaluated in order to examine the effect of substitution of zinc ions in the host matrix on the fluorescence behavior. Scanning electron microscopy studies have also been performed to investigate the average grain size of the synthesized phosphor material.     

Acoustic and thermal properties of a cellulose nonwoven natural fabric (barkcloth)

The desire to mitigate climate change due to greenhouse gas emissions has led to the exploration of plant fibers as alternative materials for various industrial applications, sound absorption inclusive. In this investigation, sound absorption properties of Antiaris toxicaria barkcloth, and the thermal insulation properties of the barkcloth epoxy laminar composites were characterized. Theoretical sound absorption models were utilized to validate the experimental data and the empirical models were in agreement with experimental data. The lowest thermal conductivity was achieved by the Antiaris toxicaria epoxy composites.     

Bleaching earth clay (pH 12.5): a green catalyst for rapid synthesis of pyranopyrazole derivatives via a tandem three-component reaction

Efficient three-component synthesis of pyranopyrazole derivatives by reacting substituted aromatic aldehydes (1), (4-chlorophenyl)acetonitrile (2) and 3-methyl-1H-pyrazol-5(4H)-one (3) using bleaching earth clay (pH 12.5) as heterogeneous catalyst and PEG-400 as green solvent is reported in the present communication. The reaction time and product yields are excellent. Catalyst and solvent recovery and reusability are very good. This is a simple, green and rapid method for synthesis of pyranopyrazole derivatives.     

A Convenient Synthesis of Novel Glycosyl Azetidines Under Mitsunobu Reaction Conditions

Abstract

A facile, simple, and high-yielding protocol for synthesis of novel glycosyl azetidines was developed from glycosyl β-amino alcohols via intramolecular cyclization under Mitsunobu reaction conditions.     

Compostability of bioplastic packaging materials: an overview

Packaging waste accounted for 78.81 million tons or 31.6% of the total municipal solid waste (MSW) in 2003 in the USA, 56.3 million tons or 25% of the MSW in 2005 in Europe, and 3.3 million tons or 10% of the MSW in 2004 in Australia. Currently, in the USA the dominant method of packaging waste disposal is landfill, followed by recycling, incineration, and composting. Since landfill occupies valuable space and results in the generation of greenhouse gases and contaminants, recovery methods such as reuse, recycling and/or composting are encouraged as a way of reducing packaging waste disposal. Most of the common materials used in packaging (i.e., steel, aluminum, glass, paper, paperboard, plastics, and wood) can be efficiently recovered by recycling; however, if packaging materials are soiled with foods or other biological substances, physical recycling of these materials may be impractical. Therefore, composting some of these packaging materials is a promising way to reduce MSW. As biopolymers are developed and increasingly used in applications such as food, pharmaceutical, and consumer goods packaging, composting could become one of the prevailing methods for disposal of packaging waste provided that industry, governments, and consumers encourage and embrace this alternative. The main objective of this article is to provide an overview of the current situation of packaging compostability, to describe the main mechanisms that make a biopolymer compostable, to delineate the main methods to compost these biomaterials, and to explain the main standards for assessing compostability, and the current status of biopolymer labeling. Biopolymers such as polylactide and poly(hydroxybutyrate) are increasingly becoming available for use in food, medical, and consumer goods packaging applications. The main claims of these new biomaterials are that they are obtained from renewable resources and that they can be biodegraded in biological environments such as soil and compost. Although recycling could be energetically more favorable than composting for these materials, it may not be practical because of excessive sorting and cleaning requirements. Therefore, the main focus is to dispose them by composting. So far, there is no formal agreement between companies, governments and consumers as to how this packaging composting will take place; therefore, the main drivers for their use have been green marketing and pseudo-environmental consciousness related to high fuel prices. Packaging compostability could be an alternative for the disposal of biobased materials as long as society as a whole is willing to formally address the challenge to clearly understand the cradle-to-grave life of a compostable package, and to include these new compostable polymers in food, manure, or yard waste composting facilities.