Structural,Morphological and Optical Properties of Well-Ordered CdO Nanostructures Synthesized by Easy-Economical Chemical Bath Deposition Technique

In this Study, Cadmium Oxide (CdO) nanostructures were synthesized by using Chemical Bath Deposition Technique. The synthesized process was carried out at room temperature. The structural and optical properties of nanostructures was characterized by XRD, SEM and UV-Vis techniques. As a result, the CdO nanostructures are oriented along (111) plane of cubic crystal structure. The morphology of CdO nanostructures showed interconnected prism-like and cauliflower-type cluster nanostructure. The UV results of this structures with high absorbtion coefficient are observed to be in accordance with the CdO nanoparticles.     

Characterization of immobilized glucose oxidase—catalase and their deactivation in a fluid-bed reactor

2-Amino-4-chloro-s-triazine, a derivative of DEAE-cellulose, and acrolein/styrene copolymer were used as supports for the immobilization of glucose oxidase and catalase after being modified with diaminohexane followed by glutaraldehyde. Immobilization was carried out with optimum glucose oxidase-catalase ratios. The activity variations of the immobilized dual-enzyme systems were investigated in relation to pH and temperature. Time-dependent gluconic acid production resulting from the oxidation of glucose was monitored in a recycling fluid-bed reactor. The deactivation rates of glucose oxidase and catalase were investigated according to the first-order reaction kinetics depending on the presence of the intermediate product H₂O₂.     

Determination of Melatonin Hormone and Neurotransmitters in Cerebrospinal Fluid: Method Validation and Uncertainty Calculations

The uncertainty of measurement for well-known neurotransmitters like serotonin, noradrenalin and gamma-aminobutyric acid (GABA), glutamate and melatonin hormone with high performance liquid chromatography?fluorescence detection was calculated after the method validation. Two methods were developed for the determination of the neurotransmitters. A derivatization step was performed for the determination of GABA and glutamate. Sensitivity, method detection limit, limit of quantification, linearity, recovery, interday and intraday precision values were calculated. Low detection limit values were obtained especially for the determination of GABA and glutamate. Then, bottom-up approach was used to calculate measurement uncertainty. The critical stages of the method were evaluated. The major sources of the uncertainty budget were calibration curves, stock solution and recovery. The calculated percentage relative uncertainty values for the compounds changed between 10.1 and 16.7.     

An improved procedure for the Beckmann rearrangement of cyclobutanones

γ-Lactams are important building blocks for the synthesis of biologically active molecules and can easily be accessed via Beckmann rearrangement of cyclobutanones. However, Beckmann fragmentation is often a competing reaction for these strained ketones. We found that performing the Beckmann rearrangement with Tamura’s reagent in the presence of aqueous HCl suppresses the undesired fragmentation reaction. This improved procedure was applied to a broad scope of substrates affording monocyclic, bicyclic, tricyclic or spirocyclic lactams.Our experimental results and DFT calculations suggest that the mechanism of the rearrangement probably involves a tetrahedral intermediate and doesn’t proceed via oxime fragmentation as in a classical Beckmann rearrangement.     

Graphene oxide integrated sensor for electrochemical monitoring of mitomycin C-DNA interaction

We present a graphene oxide (GO) integrated disposable electrochemical sensor for the enhanced detection of nucleic acids and the sensitive monitoring of the surface-confined interactions between the anticancer drug mitomycin C (MC) and DNA. Interfacial interactions between immobilized calf thymus double-stranded (dsDNA) and anticancer drug MC were investigated using differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) techniques. Based on three repetitive voltammetric measurements of 120 μg mL(-1) DNA immobilized on GO-modified electrodes, the RSD % (n = 3) was calculated as 10.47% and the detection limit (DL) for dsDNA was found to be 9.06 μg mL(-1). EIS studies revealed that the binding of the drug MC to dsDNA leads to a gradual decrease of its negative charge. As a consequence of this interaction, the negative redox species were allowed to approach the electrode, and thus increase the charge transfer kinetics. On the other hand, DPV studies exploited the decrease of the guanine signal due to drug binding as the basis for specifically probing the biointeraction process between MC and dsDNA.     

The Comparison of Electrochemical Assay and Agarose Gel Electrophoresis for the Determination of DNA Damage Induced by Kainic Acid

A possible DNA damage after interaction of kainic acid (KA) with calf thymus double stranded DNA and genomic DNA was herein determined in in vitro and in vivo conditions using; electrochemical assay and agarose gel electrophoresis. The changes in guanine signal were detected as an indicator of DNA damage in genomic DNA samples isolated from 1 or 10 mg/kg KA‐treated animals. The decreased levels of guanine signal were found as 29% and 33% by 1 and 10 mg/kg KA treatment when compared to controls, respectively. The results of gel electrophoresis confirmed DNA damage obtained in identical samples by electrochemical method.     

Characterization of sugar palm (Arenga pinnata) fibres

The aim of this study was to characterize tensile and thermal properties of sugar palm (Arenga pinnata) fibres obtained from different heights (1, 3, 5, 7, 9, 11, 13, and 15?m) of sugar palm tree. This study has confirmed that in a mature sugar palm tree, degradation was occurred and altered the properties of its fibre. Fibres obtained at the area of live (green) palm frond were found to have a better tensile properties as a result of its optimum chemical composition especially cellulose, hemicelluloses and lignin. For the fibre obtained from the upper part of sugar palm tree, it shows slightly decreasing trend in tensile properties compared to mature fibres. It is due to the fibres are juvenile where their cell walls are progressively built up thus give slightly lower properties than matured fibres. For the fibre obtained from the area of dead palm frond, the fibres are considered to be degraded biologically. It is believed that polymeric chains in microfibrils were broken and their cellulose content was decreased which demonstrated inferior properties (tensile strength, modulus, elongation at break and toughness). The use of such fibre for application as reinforcing fibre in composite is not recommended since the strength of the fibre and composite will be reduced. There were four phases of decomposition of the fibres where the sequence of decomposition started with decomposition of moisture, followed by hemicelluloses, then cellulose and next is lignin while the ash was the last component left. The thermal degradation of these components were found in ranges of 45?C123, 210?C300, 300?C400, 160?C900 and 1723?°C, respectively. Thermogravimetric analysis and derivative thermogravimetric analysis curves showed that the fibre of 1?m showed higher thermal stability than the fibres of 3?C15?m. The different thermal stability for each fibre was due to different chemical compositions especially when the fibre containing high ash content which result in higher thermal stability.     

Catalyst functional group cooperativity in the amino acid-catalysed nitroaldol condensation reaction

Several amino acids and their derivatives have been evaluated as organic catalysts for the nitroaldol reaction. It was found that when an unprotected amino group and an unprotected carboxylate group were present in the organocatalyst, both the nitroaldol reaction and subsequent elimination could occur to afford nitroalkenes from aromatic aldehydes and nitromethane. The best results were obtained by use of γ-amino acids derived from l-glutamine. It is suggested that the amino group is important for intermediate Schiff base formation and that the free carboxylate group facilitates the elimination step.