Synthesis of Pt and Pt-Fe nanoparticles supported on MWCNTs used as electrocatalysts in the methanol oxidation reaction

This work reports a feasible synthesis of highly-dispersed Pt and Pt-Fe nanoparticles supported on multiwall carbon nanotubes （MWCNTs） without Fe and multiwall carbon nanotubes with iron （MWCNTs-Fe） which applied as electrocatalysts for methanol electrooxidation. A Pt coordination complex salt was synthesized in an aqueous solution and it was used as precursor to prepare Pt/MWCNTs, Pt/MWCNTs-Fe, and Pt-Fe/MWCNTs using FeC12.4H20 as iron source which were named S 1, S2 and S3, respectively. The coordination complex of platinum （TOA）2PtC16 was obtained by the chemical reaction between （NH4）2PtC16 with tetraoctylammonium bromide （TOAB） and it was characterized by FT-IR and TGA. The materials were characterized by Raman spectroscopy, SEM, EDS, XRD, TEM and TGA. The electrocatalytic activity of Pt-based supported on MWCNTs in the methanol oxidation was investigated by cyclic voltammetry （CV） and chronoamperometry （CA）. Pt-Fe/MWCNTs electrocatalysts showed the highest electrocatalytic activity and stability among the tested electrocatalysts due to that the addition of ＂Fe＂ promotes the OH species adsorption on the electrocatalyst surface at low potentials, thus, enhancing the activity toward the methanol oxidation reaction （MOR）.

A Multiparameter Colloidal Titrations for the Determination of Cationic Polyelectrolytes

In water treatment processes and conditioning drinking water, PEs are widely used;however, their environmental impact is still doubtful, since residual concentrations increase organic matter content and represents a potential health hazard. This paper demonstrates a multiparametric study of two colloidal titration methods: spectrophotometric and zeta potential end point detection. The first one was optimized to guarantee the accuracy of cationic commercial PE quantification. It includes the indicator dose optimization using analytical criteria for competing equilibria, a calibration curve for two ranges of CPE concentration (1 - 5 ppm and 5 - 100 ppm) and the interference study of flocculant and Sn in the CPE quantification. The second method provides a physicochemical validation of the electric surface phenomena occurring during the colloidal titration and the end point detection. As an additional contribution the zeta potential titration was discussed and proposed as an alternative method for quantifying CPE when the sample is metal free.

Molecular Modeling of Quinoline-Based Compounds as Potential Dual Inhibitors of Reverse Transcriptase and Integrase of HIV

As follow-up of our past publication?[1], we propose that quinolones (as part of the pyridinone family) are capable to increase the number of interactions with HIV reverse transcriptase (RT) or integrase (IN) by adding a halogen in position C-8 of aromatic portion of the quinolones. This addition could help with the activity of dual inhibitors of RT and IN. In this work, we add a chlorine atom with the rationale to identify in the docking simulations a halogen interaction with the oxygen in the near aminoacids in the binding pockets of RT and IN enzymes. Our docking studies started with RT and 320 structures. Later, we took 73 structures with good results in docking with RT. The structures that we choose contain ester or acids groups in C-3 due the structural similarity with groups in charge to interact with the Mg++ ions in Elvitegravir. In conclusion, we obtained 14 structures that could occupy the allosteric pocket of RT and could inhibit the catalytic activity of IN, for this reason could be dual inhibitors. A major perspective of this work is the synthesis and testing of the potential dual inhibitors designed.

Melatonin and Circadian Rhythm: Aging, Cancer, and Mechanism

The circadian clock is involved with many aspects of biological processes in animals and plants. Melatonin is a pineal hormone which is known to play a widespread role in the biochemistry of the circadian clock. The present review addresses the clock and melatonin in relation to aging and cancer, which are important aspects of medicine and biochemistry. The literature contains a large variety of associations of these areas with melatonin and circadian rhythm. Mechanistic aspects are addressed with emphasis on the unifying theme based on electron transfer-free radicalsoxidative stress.

New Developments in the Mechanism of Drug Action and Toxicity of Conjugated Imines and Iminiums, including Related Alkaloids

This review deals with mechanism and physiological activity of conjugated imine and iminium species, including those in the alkaloid category. An appreciable number can be found in the Merck Index. There is focus in mode of action on electron transfer (ET), reactive oxygen species (ROS), oxidative stress (OS) and reduction potential in the prior review. These aspects can be involved in both therapeutic action and toxicity. A unifying mechanistic approach involving ET-ROS-OS is applied to synthetic drugs and alkaloids in the imineiminium category in relation to both beneficial and adverse effects. Insight at the basic, molecular level can aid in practical pharmaceutical design.

Electrochemical and Photoelectrochemical Decoloration of Amaranth Dye Azo Using Composited Dimensional Stable Anodes

In this paper we report the results of our experimental work conducted to decoloration of a well-known highly toxic Amaranth dye by electrochemical and photoelectrochemical methods. Throughout this investigation were used two different Dimensional Stable Anode (DSA) electrodes, namely, IrO2-Ru2O-SnO2-TiO2/Ti and Ru2O-SnO2-TiO2/Ti. The experimental results show that IrO2-Ru2O-SnO2-TiO2/Ti electrode has higher performance on amaranth decoloration than Ru2O-SnO2-TiO2/Ti electrode, but with the disadvantage of higher energy consumption. For higher degradation of Amaranth dye with both DSA electrodes, the process was carried out via photoelectrochemical method. Our experimental results clearly shown the decrease in absorbance of all UV-Vis peaks due to the mineralization of the azo dye;also, it was noteworthy photoelectrochemical process consumes less energy under the same experimental conditions than electrochemical process. The IrO2-Ru2O-SnO2-TiO2/Ti electrode reaches a higher degradation degree of Amaranth solutions than Ru2O-SnO2-TiO2/Ti electrode using a photoelectrochemical technique.

Flexibility of the Lumbar Intervertebral Disc in Bending and Torsion： Experimental and Finite Element Study

Intervertebral disc flexibility is influenced by lifestyle, loading history, trauma, preexisting conditions, age and degeneration. With regard to degeneration, intervertebral discs become less flexible and stiffer. In this study, a testing protocol using bending and torsion loading was developed to gain the flexibility curves and stiffness often cadaveric lumbar discs. Measurements of rotation in the sagittal plane （flexion-extension）, coronal plane （right-lefl lateral bending） and transverse plane （torsion） due to a 5 N-m load are reported. Results show that overall normal discs are more flexible and behave in a nonlinear fashion. The testing results were used in a develop t＇mite element model of an intervertebral disc to investigate the stresses and strains in the disc components： annulus fibrosus and nucleus pulposus with regard to degeneration. Simulation of bending and torsion loadings show large strains in the annulus and nucleus from a normal disc, in contrast higher stresses develop in the annulus from a degenerated disc. The proposed methodology is novel, versatile, functional and economic with implications in bioengineering, medical sciences and the clinical field.