Synthesis of a cellulose‐grafted polymeric support and its application in the reductions of some carbonyl compounds

The reduction of carbonyl compounds by borohydride supported on a cellulose–anion exchange resin is known. The synthesis of a graft copolymer of cellulose and poly(4‐vinyl pyridine) [CellO‐g‐poly(4‐VP)] has been carried out with ceric ions as a redox initiator. A postgrafting treatment of CellO‐g‐poly(4‐VP) with sodium borohydride has produced CellO‐g‐poly(4‐VP) borane, a polymer‐supported reducing agent. Optimum conditions pertaining to the maximum percentage of grafting have been evaluated as a function of the concentrations of the initiator, monomer, and nitric acid, amount of water, time, and temperature. The maximum percentage of grafting (585%) has been obtained with 0.927 mol/L of 4‐vinyl pyridine and 0.018 mol/L of ceric ammonium nitrate in 120 min at 45°C. The polymeric support, CellO‐g‐poly(4‐VP) borane, has been used for reduction reactions of different carbonyl compounds such as benzaldehyde, cyclohexanone, crotonaldehyde, acetone, and furfural. The graft copolymer has been characterized with IR and thermogravimetric analysis. The grafted cellulose has been found to be thermally stable. The reduced products have been characterized with IR and NMR spectral methods. The reagent has been reused for the reduction of a fresh carbonyl compound, and it has been observed that the polymeric reagent reduces the compounds successfully but with a little lower product yield. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis of tetrahydrofuran ring containing oligoethylene glycol ethers from the seed oil of Vernonia anthelmintica

A tetrahydrofuran ring containing oligoethylene glycol ethers has been synthesized from the seed oil of Vernonia anthelmintica. The seed oil was reacted with mono-, di-, and triethylene glycols in the presence of boron trifluoride etherate, followed by saponification and esterification (MeOH/H⁺). The oligoethylene glycol ethers thus obtained were epoxidized with perbenzoic acid. The 9,10-epoxy oligoethylene glycol ethers so formed were intramolecularly cyclized in dry benzene using boron trifluoride etherate as a catalyst to yield the tetrahydrofuran ring containing oligoethylene glycol ethers; methyl 9,12-epoxy, 10-hydroxy-13-[2-hydroxyethyl-1-oxy]; methyl 9,12-epoxy,10-hydroxy-13-[2-hydroxy-3-oxapentyl-1-oxy] and methyl 9,12-epoxy,10-hydroxy-13-[8-hydroxy-3,6-dioxaoctyl-1-oxy]octadecanoates, respectively.     

Selective solid-phase extraction of rare earth elements by the chemically modified Amberlite XAD-4 resin with azacrown ether

A selective solid-phase extraction procedure using chemically modified Amberlite XAD-4 with monoaza dibenzo 18-crown-6 ether was investigated for the preconcentration and separation of La(III), Nd(III) and Sm(III) in synthetic solution. Before loading samples on synthesized adsorbent adjust pH 4.5 by suitable buffer solution. The adsorbed rare earth elements were eluted by 2 M hydrochloric acid. Various parameters like preconcentration, breakthrough capacity, flow rate were investigated. The limits of detection (n = 5) and limits of quantification (n = 5) for La(III), Nd(III) and Sm(III) were founded 3.9, 4.2 and 7.4 μg L^?1 and 13, 15 and 26 μg L^?1, respectively. The eluted metal ions were determined by ICP-AES.     

Bisnaphthalimidopropyl Derivatives as Inhibitors of Leishmania SIR2 Related Protein 1

The NAD⁺‐dependent deacetylases, namely sirtuins, are involved in the regulation of a variety of biological processes such as gene silencing, DNA repair, longevity, metabolism, apoptosis, and development. An enzyme from the parasite Leishmania infantum that belongs to this family, LiSIR2RP1, is a NAD⁺‐dependent tubulin deacetylase and an ADP‐ribosyltransferase. This enzyme's involvement in L. infantum virulence and survival underscores its potential as a drug target. Our search for selective inhibitors of LiSIR2RP1 has led, for the first time, to the identification of the antiparasitic and anticancer bisnaphthalimidopropyl (BNIP) alkyl di‐ and triamines (IC₅₀ values in the single‐digit micromolar range for the most potent compounds). Structure–activity studies were conducted with 12 BNIP derivatives that differ in the length of the central alkyl chain, which links the two naphthalimidopropyl moieties. The most active and selective compound is the BNIP diaminononane (BNIPDanon), with IC₅₀ values of 5.7 and 97.4 μM against the parasite and human forms (SIRT1) of the enzyme, respectively. Furthermore, this compound is an NAD⁺‐competitive inhibitor that interacts differently with the parasite and human enzymes, as determined by docking analysis, which might explain its selectivity toward the parasitic enzyme.     

Pressure induced transformations in condensed and molecular phases of C60

Solid C₆₀ is known to undergo dimerization under suitable conditions of temperature and pressure. We use a potential model (6-exponential potential) to study the changes leading to the formation of various dimers by hydrostatic pressure on C₆₀ solid at elevated temperatures. We have earlier shown, using Tersoff and Brenner potentials, that a system of two bucky-balls can form a dimer by bonding in different ways, when they start with different orientations at close distances. Based on this, we suggest the required preconditions (P-T curve) for the formation of different dimers from the pristine solid. Stability of the bucky-ball under internal or external pressure has also been studied using Tersoff and Brenner potentials. These two potentials have been compared for their applicability under high pressure conditions as well as for dimerization. We have also estimated the bulk modulus of the bucky-ball at several pressures (under which the molecule remains stable). The values of bulk modulus agree closely with those reported in earlier calculations around zero pressure. When the pressure inside the bucky-ball exceeds 116 GPa, it is seen to break open. This is in close agreement with the findings of molecular dynamics calculations.     

Characterization of PA-12 specimens fabricated by projection sintering at various sintering parameters

Large area projection sintering (LAPS) promises to be a new method in the field of additive manufacturing. Developed in the Mechanical Engineering Department, University of South Florida, LAPS uses long exposure times over a broad area of powder to fuse into dense, reproducible materials. In contrast, LS, a common powder-based additive manufacturing, uses a focused beam of light scanned quickly over the material. Local regions of concentrated high-energy bursts of light lead to higher peak temperatures and differing cooling dynamics and overall crystallinity. The mechanical properties of laser sintered specimens suffer because of uneven particle fusion. LAPS offers the capacity to fine-tune fusion properties through enhanced thermodynamic control of the heating and cooling profiles for sintering. Further research is required to identify the relationship between LAPS build settings and part properties to enable the fabrication of custom parts with desired properties. This study examines the influence of LAPS sintering parameters on chemical structures, crystallinity, mechanical, and thermal properties of polyamide-12 specimens using powder X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry, small-angle X-ray scattering, scanning electron microscopy, and microhardness testing. It was observed that higher crystallinity was imparted to specimens that were sintered for a shorter time and vice versa.     

Proton Nuclear Magnetic Resonance-Based Method for the Quantification of Epoxidized Methyl Oleate

Epoxidized methyl esters (EMO) with their high oxirane ring reactivity, acts as a raw material in the synthesis of various industrial chemicals including polymers, stabilizers, plasticizers, glycols, polyols, carbonyl compounds, biolubricants etc. EMO has been generally quantified by the gas chromatography (GC) and high-performance liquid chromatography (HPLC) techniques. Taking into the account of the limitations of these techniques, two qHNMR-based equations have been proposed for the quantification of EMO in the mixture of EMO and methylesters (MO). The validity of the proposed method was determined using standard mixtures of MO and EMO having different molar concentrations. The developed equations have been applied on the samples of EMO prepared from oleic acid in two-step process viz., esterification followed by epoxidation. The qHNMR-based EMO quantification showed acceptable agreement with the results obtained from HPLC analysis.     

An Improved Protocol for Agrobacterium-Mediated Transformation in Subterranean Clover (Trifolium subterraneum L.)

Subterranean clover (Trifolium subterraneum) is the most widely grown annual pasture legume in southern Australia. With the advent of advanced sequencing and genome editing technologies, a simple and efficient gene transfer protocol mediated by Agrobacterium tumefaciens was developed to overcome the hurdle of genetic manipulation in subterranean clover. In vitro tissue culture and Agrobacterium transformation play a central role in testing the link between specific genes and agronomic traits. In this paper, we investigate a variety of factors affecting the transformation in subterranean clover to increase the transformation efficiency. In vitro culture was optimised by including cefotaxime during seed sterilisation and testing the best antibiotic concentration to select recombinant explants. The concentrations for the combination of antibiotics obtained were as follows: 40 mg L⁻¹ hygromycin, 100 mg L⁻¹ kanamycin and 200 mg L⁻¹ cefotaxime. Additionally, 200 mg L⁻¹ cefotaxime increased shoot regeneration by two-fold. Different plant hormone combinations were tested to analyse the best rooting media. Roots were obtained in a medium supplemented with 1.2 µM IAA. Plasmid pH35 containing a hygromycin-resistant gene and GUS gene was inoculated into the explants with Agrobacterium tumefaciens strain AGL0 for transformation. Overall, the transformation efficiency was improved from the 1% previously reported to 5.2%, tested at explant level with Cefotaxime showing a positive effect on shooting regeneration. Other variables in addition to antibiotic and hormone combinations such as bacterial OD, time of infection and incubation temperature may be further tested to enhance the transformation even more. This improved transformation study presents an opportunity to increase the feeding value, persistence, and nutritive value of the key Australian pasture.     

Characterisation and functional properties of proteins of some Indian chickpea (Cicer arietinum) cultivars

BACKGROUND: Chickpea (Cicer arietinum L.) proteins have received attention during recent years owing to their higher biological values and better functional ingredients than oilseed proteins. In this study the composition, fractionation, electrophoretic behaviour and functional properties of five chickpea protein concentrates were determined. RESULTS: The chickpea proteins contained 15.9–54.8 g kg^?1 albumin, 48.9–154.1 g kg^?1 globulin, 39.2–76.5 g kg^?1 glutelin and traces of prolamin. Electrophoresis of the various fractions revealed that albumin and globulin were made up of sub‐units of different molecular weights ranging from 7 to 96 kDa. Water and oil absorption of the protein concentrates varied from 1.15 to 2.75 g g^?1 and from 2.60 to 5.65 g g^?1 respectively. Foaming capacity and foam stability of the protein concentrates were good and improved with the addition of salt (10 g L^?1 NaCl) or sugar (100 g L^?1 sucrose) at both isoelectric and neutral pH. Emulsifying capacity and emulsion stability of the protein concentrates were good and excellent respectively. CONCLUSION: Protein concentrates prepared from chickpeas have potential use in food formulations owing to their good emulsifying/foaming and water/oil‐binding capacities. Copyright © 2008 Society of Chemical Industry