The Use of Megamolecular Polysaccharide Sacran in Food and Biomedical Applications

Natural polymer is a frequently used polymer in various food applications and pharmaceutical formulations due to its benefits and its biocompatibility compared to synthetic polymers. One of the natural polymer groups (i.e., polysaccharide) does not only function as an additive in pharmaceutical preparations, but also as an active ingredient with pharmacological effects. In addition, several natural polymers offer potential distinct applications in gene delivery and genetic engineering. However, some of these polymers have drawbacks, such as their lack of water retention and elasticity. Sacran, one of the high-molecular-weight natural polysaccharides (megamolecular polysaccharides) derived from Aphanothece sacrum (A. sacrum), has good water retention and elasticity. Historically, sacran has been used as a dietary food. Moreover, sacran can be applied in biomedical fields as an active material, excipient, and genetic engineering material. This article discusses the characteristics, extraction, isolation procedures, and the use of sacran in food and biomedical applications.     

Chemistry of Phosphorus Ylides. Part 40. Synthesis of Pyrazoles by the [3 + 2] Cycloaddition of Diazo Compounds with Wittig Reagents as Antimicrobial Compounds

A comparative study between the reactions of active phosphacumulenes and stabilized phosphonium ylides on some diazo compounds have been performed. A number of substituted phosphanylidene spiro pyrazoles have been synthesized from the reaction of the active phosphacumulenes and the diazo derivatives. On the other hand, treatment of the diazo substrates with the stabilized phosphonium ylides led to the formation of the corresponding ylidenes and diazenyl phosphanylidenes. The antimicrobial activities for the new compounds are also reported.     

Electrochemical Stability of the Reconstructed Fe3O4(001) Surface

Establishing the atomic-scale structure of metal-oxide surfaces during electrochemical reactions is a key step to modeling this important class of electrocatalysts. Here, we demonstrate that the characteristic (√2×√2)R45° surface reconstruction formed on (001)-oriented magnetite single crystals is maintained after immersion in 0.1 M NaOH at 0.20 V vs. Ag/AgCl and we investigate its dependence on the electrode potential. We follow the evolution of the surface using in situ and operando surface X-ray diffraction from the onset of hydrogen evolution, to potentials deep in the oxygen evolution reaction (OER) regime. The reconstruction remains stable for hours between −0.20 and 0.60 V and, surprisingly, is still present at anodic current densities of up to 10 mA cm⁻² and strongly affects the OER kinetics. We attribute this to a stabilization of the Fe₃O₄ bulk by the reconstructed surface. At more negative potentials, a gradual and largely irreversible lifting of the reconstruction is observed due to the onset of oxide reduction.     

Synthesis and thermal studies of tetraaza macrocylic ligand and its transition metal complexes. DNA binding affinity of copper complex

A Tetraaza Macrocylic Ligand (H2L) and its complexes, [Cd(H2L)(OH2)2](NO3)(2)·1/2OH2 (I), [Co(H2L)(OH2)](NO3)(2)·1/2OH2 (II), [Cu(H2L)(NO3)2]·3/2OH2 (III) and [Ni(H2L)(NO3)(OH2)]NO3·OH2 (IV), have been synthesized and characterized on the basis of elemental analysis, molar conductivity, 1H NMR, UV-vis, FT-IR and mass spectroscopy. All results confirm that the prepared compounds have 1:1 metal-to-ligand stoichiometry, octahedral configuration and the ligand behaves as a neutral tetradendate towards the metal ions. [CdL(OH2)2] (V), [CoL(OH2)2] (VI), [CuL(OH2)2] (VII) and [Ni(H2L)(NO3)2] (VIII) were synthesized pyrolytically in solid state from corresponding compounds (I-IV). Analytical results of complexes (V-VIII) show that the ligand behaves either as a neutral tetradendate or dianionic tetradentate ligand towards the metal ions. The binding of H2L and its copper complex (III) to DNA has been investigated by ultraviolet absorption spectroscopy. The experiments indicate that H2L and its copper complex (III) can bind to DNA through an intercalative mode. The H2L and its copper complex (III) exhibited anti-tumor activity against Ehrlich Acites Carcinoma (E.A.C) at the concentration of 100 μg/ml.     

Single, binary and multi-component adsorption of some anions and heavy metals on environmentally friendly Carpobrotus edulis plant

A low-cost adsorbent and environmentally friendly adsorbent from Carpobrotus edulis plant was used for the removal of NO(3)(-), H(2)PO(4)(-), Pb(2+) and Cd(2+) ions from single, binary and multi-component systems. The efficiency of the adsorbent was studied using batch adsorption technique under different experimental conditions by varying parameters such as pH, initial concentration and contact time. In single component systems, the dried C. edulis has the highest affinity for Pb(2+), followed by NO(3)(-), Cd(2+) and H(2)PO(4)(-), with adsorption capacities of 175mg/g, 125mg/g, 28mg/g and 26mg/g, respectively. These results showed that the adsorption of NO(3)(-) and H(2)PO(4)(-) ions from single and binary component systems can be successfully described by Langmuir and Freundlich isotherms. Freundlich adsorption model, showed the best fit to the single and binary experimental adsorption data. These results also indicated that the adsorption yield of Pb(2+) ion was reduced by the presence of Cd(2+) ion in binary metal mixture. The competitive adsorption of NO(3)(-), H(2)PO(4)(-), Pb(2+) and Cd(2+) ions on dried C. edulis plant shows that NO(3)(-) and H(2)PO(4)(-) anions are able to adsorb on different free binding sites and Pb(2+) and Cd(2+) cations are able to adsorb on the same active sites of C. edulis particles. The dried C. edulis was found to be efficient in removing nitrate, phosphate, cadmium and lead from aqueous solution as compared to other adsorbents already used for the removal of these ions.     

Triazacyclophane (TAC)-scaffolded histidine and aspartic acid residues as mimics of non-heme metalloenzyme active sites

We describe the synthesis and coordination behaviour to copper(II) of two close structural triazacyclophane-based mimics of two often encountered aspartic acid and histidine containing metalloenzyme active sites. Coordination of these mimics to copper(I) and their reaction with molecular oxygen leads to the formation of dimeric bis(μ-hydroxo) dicopper(II) complexes.     

Biotechnological Production of Xylitol: Enhancement of Monosaccharide Production by Post-Hydrolysis of Dilute Acid Sugarcane Hydrolysate

Dilute-acid hydrolysis pretreatment of sugarcane bagasse resulted in release of 48% (18.4 g/L) of the xylan in the hemicellulose fraction into the hydrolysate as monomeric xylose. In order to enhance the recuperation of this monomer, a post-hydrolysis stage consisted of thermal treatment was carried out. This treatment resulted in an increase in xylose release of 62% (23.5 g/L) of the hemicellulose fraction. Original and post-hydrolysates were concentrated to the same levels of monomeric xylose in the fermentor feed. During the fermentation process, cellular growth was observed to be higher in the post-hydrolysate (3.5 g/L, Y _x/s?=?0.075 g cells/g xylose) than in the original hydrolysate (2.9 g/L, Y _x/s?=?0.068 g cells/g xylose). The post-treated hydrolysate required less concentration of sugars resulting in a lower concentration of fermentation inhibitors, which were formed primarily in the dilute acid hydrolysis step. Post-hydrolysis step led to a high xylose–xylitol conversion efficiency of 76% (0.7 g xylitol/g xylose) and volumetric productivity of 0.68 g xylitol/L h when compared to 71% (0.65 g xylitol/g xylose and productivity of 0.61 g xylitol/L h) for the original hemicellulosic hydrolysate.