Redox activity of melanin from the ink sac of Sepia officinalis by means of colorimetric oxidative assay

The redox properties of natural extract from cuttlefish ink sac (Sepia officinalis) and synthetic melanin used as a biomimetic in melanin structural investigation were determined by comparison of this phenol-based heterogeneous pigment with gallic acid used as a standard in Folin–Ciocalteu colorimetric assay widely employed for characterisation of oxidative properties of biomaterials. Reactivity of sepia melanin reported here is much higher than previously indicated and this protocol should allow the redox characterisation of all melanins irrespective of their origin and composition.     

Nature of the metal-support interaction in bifunctional catalytic Pt/H-ZSM-5 zeolite

The metal-support interaction of a dispersed Pt atom on H-ZSM-5 zeolite has been investigated by using an embedded cluster and cluster models with the density functional theory/B3LYP functional method. We found that the Pt atom interacts with a Br?nsted proton and a nearby framework oxygen. Interaction with the framework oxygen causes electron transfer from the zeolite to the Pt atom. Concurrently, a Br?nsted proton stabilizes the Pt atom on the zeolite surface by withdrawing excess electron density from the Pt atom. These charge transfers result in a zero net charge on the Pt atom while changing its orbital occupation. The binding energy of Pt on the Br?nsted acid was 15 kcal/mol. Inclusion of the Madelung potential by Surface Charge Representation of the Electrostatic Embedded Potential method (SCREEP) had small effects on structure and charge density of Pt/H-ZSM-5 but it shifted the stretching mode of CO toward a higher frequency by almost 40 cm(-1). The frequency shift of absorbed CO calculated with embedded cluster models was from 8 to 11 cm(-1) red shift, compared to 20 cm(-1) red shift from experiment. This implies that not only the electronic state of the Pt atom but also the Madelung potential of the support is responsible for the observed small red shift of CO on the Pt-H-ZSM-5.     

Comparison of different Vetiver grass pretreatment techniques and their impact on immobilized butanol production by Clostridium beijerinckii TISTR 1461

Cellulose - Immobilization of microbe cells has been considered as a potential alternative for enhancing biobutanol productivity through acetone-butanol-ethanol (ABE) fermentation. Vetiver grass...     

Molecular dynamics of ��-CD in water/co-solvent mixtures

Molecular dynamics (MD) simulations on ??-cyclodextrin (??-CD) in water, ethanol (EtOH), methanol (MeOH) and mixtures of these solvents have been carried out at 300 K over a time period of 15 ns using the AMBER force field. The hydrated X-ray crystallographic structure has four water molecules inside the cavity, defined by a more precise boundary for the ??-CD cavity. From the simulations, 2?C4 encapsulated water molecules are most probably found. In an ethanol co-solvent system, the ??-CD cavity is occupied with one ethanol molecule located in two discrete sites: below and above the O4(n) plane, which is in agreement with experimental results. In all systems, the average values of tilt angles of the obtained structures are higher than the tilt angles of the X-ray structures. The investigations of the alcohol orientations in co-solvent mixtures reveal the hydrophobic environment of the cavity and the hydrophilic atmosphere at both rims of ??-CD.     

Effect of Melanomal Proteins on Sepia Melanin Assembly

Melanins are phenol-based pigments with the potential for widespread applications, including bioelectronics and tissue engineering. The concentration-dependent structural transition of sepia melanin in water is analyzed. This biopolymer at high concentration gives the well-known nanospheres, whereas sample dilution gives unforeseen nanofibres exhibiting the structural features of mature amyloid fibrils. We propose a mechanism of pigment self-assembly dependent on the interaction of residual melanosomal protein(s) with eumelanin heteropolymer. Our results contribute to understanding the peculiar physicochemical properties of this ubiquitous pigment.     

Use of isotope hydrology for groundwater resources study in Upper Chi river basin

The Upper Chi river basin is located in the vicinity of Chaiyaphum province, northeastern Thailand. Groundwater management in the drought affected area of fractured Mesozoic siliciclastic rocks groundwater system was challenged by the approaches of isotope and chemical techniques. The local meteoric water line (LMWL) of the study area provide lower slope (δD = 6.8508δ¹⁸O ? 0.8013) and more depleted average annual rainfall (δ¹⁸O = ?7.6 %ο) when compare to LMWL of Bangkok due to higher evaporation. The surface water mainly exhibits an evaporation effect and can be clearly divided into two groups, the upper reaches and the downstream areas, with approximate separated in δ¹⁸O by ?4.0 %ο. The groundwater system in the area can be divided into seven subareas based on the stable isotope characteristics and groundwater dating by radiocarbon and tritium methods. Nong Bua Deang subarea, Kang Kro subarea, and Thep Satit subarea, the most upstream system which were separated by thick aquitards of Phra Wihan sandstones, are classified as the upper reach area. The groundwater samples are characterized in two traits: the upstream group shows older groundwater ages (<80.0 % modern carbon, PMC) because of less interaction with surface water and the downstream group, near main channels and reservoirs, exhibit younger groundwater ages because of contribution of surface water in the recharge area. Bamnet Narong subarea and Muang Chaiyaphum subarea are classified as the middle reach area. The groundwater shows rapidly recharge from rainfall, the results of radiocarbon provide younger ages. The downstream characteristic which is closely interaction of extremely evaporated surface, were found in Kon Sawan-Mancha Kiri subarea and Ban Phai subarea. Almost all the groundwater samples are related to younger ages except the wells near the upper tributaries. The groundwater management can be proposed by attending to conservation policy in the upper reach area, and some parts of Ban Phai subarea in which groundwater is slowly replenished slowly, as well as groundwater exploration will be expanded in the Bamnet Narong subarea and the Muang Chaiyaphum subarea which is the most effective zones for groundwater developments.     

High-rate electrochemical performance and structure elucidation of hydrothermally synthesized nickel zincate nanorods

Journal of Solid State Electrochemistry - For the first time, nanorods of nickel zincate (NiZnO2) have been synthesized by the hydrothermal method and used in supercapacitor electrode fabrication....