I-Kinetic And Mechanistic Investigations Of Amino Acid Substrates Reactivities With Ferryl Species

ABSTRACT I-KINETIC AND MECHANISTIC INVESTIGATIONS OF AMINO ACID SUBSTRATES REACTIVITIES WITH FERRYL SPECIES II-SYNTHESIS AND CHARACTERIZATION OF DERIVATIVES OF THE BN-TPEN LIGAND AND THEIR METAL COMPLEXES by AHMED IBRAHIM YOUSSEF ABOUELATTA MAY 2011 Advisor: Dr. Jeremy Jacob Kodanko Major: Chemistry (Organic) Degree: Doctor of philosophy The reactivity of tryptophan, methionine, aspartic acid, glutamic acid, histidine and hydrochloride salt of lysine amino acid substrates with the N4Py ferryl species was studied by UV-vis spectroscopy and product characterization. Based on kinetic isotope effect studies and product analysis, an ET-PT mechanism was proposed for the reaction of tryptophan substrate with N4Py ferryl and an oxygen-atom transfer mechanism was proposed for the reaction of methionine substrate with N4Py ferryl species. The reactivity of the five significantly reactive amino acid substrates (Cys, Tyr, Trp, Met and Gly) amino acid substrates was investigated with Me-N4Py, Bn-TPEN and TMC ferryl species and compared to their reactivity with N4Py ferryl species. This study indicated that the Bn-TPEN ferryl species was the most reactive with these five substrates followed by N4Py and Me-N4Py which were more reactive than TMC ferryl species. The different relative rate constants obtained for the substrates with different ferryl species and the slow reactivity of methionine substrate with Me-N4Py ferryl with respect to N4Py ferryl suggested that steric factor is involved in controlling these reactions. Studies towards the modification of the structure of the Bn-TPEN ligand were achieved and three new Bn-TPEN derivatives were synthesized and characterized. In addition, the synthesis and characterization of the racemic and enantioenriched Zn(II) and Fe(II) complexes and the enantioenriched Co(III) metal complexes of the Bn-CDPy3 was performed. These metal complexes were characterized with X-ray crystallography, circular dichroism, UV-vis, IR, 1-D and 2-D NMR spectroscopy in addition to elemental analysis and mass spectrometry. Based on these experiments, the three Bn-CDPy3 metal complexes were found to favor one isomer (C) over the other four possible isomers. The reason of the stability of isomer C over isomers A, B, D and E was attributed to a combination of steric and electronic effects

Design of Extended Channel Ge-source TFET for Low Power Applications

In this paper, a novel design of a TFET structure using Ge-source and extending a part of the channel into the source is proposed. The DC performance is analyzed by evaluating the ON current, ION/IOFF ratio and subthreshold swing (SS). Moreover, the high-frequency performance is inspected in terms of transconductance (gm) and unit-gain cutoff frequency (fT). All simulations are performed utilizing 2D SILVACO TCAD. It is demonstrated that the ON current and the cut-off frequency can be simultaneously improved by appropriate design of the proposed structure

An Autonomous Wearable Sensor Node for Long-Term Healthcare Monitoring Powered by a Photovoltaic Energy Harvesting System

oai:ojs.ijet.ise.pw.edu.pl:article/2503In this paper, an autonomous wearable sensor node is developed for long-term continuous healthcare monitoring. This node is used to monitor the body temperature and heart rate of a human through a mobile application. Thus, it includes a temperature sensor, a heart pulse sensor, a low-power microcontroller, and a Bluetooth low energy (BLE) module. The power supply of the node is a lithium-ion rechargeable battery, but this battery has a limited lifetime. Therefore, a photovoltaic (PV) energy harvesting system is proposed to prolong the battery lifetime of the sensor node. The PV energy harvesting system consists of a flexible photovoltaic panel, and a charging controller. This PV energy harvesting system is practically tested outdoor under lighting intensity of 1000 W/m2. Experimentally, the overall power consumption of the node is 4.97 mW and its lifetime about 246 hours in active-sleep mode. Finally, the experimental results demonstrate long-term and sustainable operation for the wearable sensor node

The effect of minimum quantity lubrication in the intermittent turning of magnesium based on vibration signals

The present work shows an experimental investigation on intermittent turning based on vibration signals. The dependence of vibrations on the feed rate, minimum quantity lubrication (MQL) flow rate and the type of the interruption of the workpiece is evaluated. The results indicate that a part of the vibrations depends on the flow rate of the MQL system and its interaction with the feed rate, finding no dependency on the type of interruption. The influence of the MQL system is greater when machining at the lower feed rate. In addition, a strong relation between surface roughness and vibrations is identified. However, this relation is quite different depending on the environment used. In general, under dry conditions, the higher the vibrations the higher the surface roughness, while the opposite occurs when the MQL system is used.publishe

The Reaction of a High‐Valent Nonheme Oxoiron(IV) Intermediate with Hydrogen Peroxide

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/91353/1/5472_ftp.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/91353/2/ange_201200901_sm_miscellaneous_information.pd

Design of Extended Channel Ge-source TFET for Low Power Applications

In this paper, a novel design of a TFET structure using Ge-source and extending a part of the channel into the source is proposed. The DC performance is analyzed by evaluating the ON current, ION/IOFF ratio and subthreshold swing (SS). Moreover, the high-frequency performance is inspected in terms of transconductance (gm) and unit-gain cutoff frequency (fT). All simulations are performed utilizing 2D SILVACO TCAD. It is demonstrated that the ON current and the cut-off frequency can be simultaneously improved by appropriate design of the proposed structure