Study of the histidine complex of uranium(IV): synthesis, spectrophotometric, magnetic and electrochemical properties

We synthesized the novel histidine complex of uranium(IV). A 1:3 mole ratio was found between metal and ligand by the mole ratio method, while –NH2 and –COO– groups of histidine behave as coordinating sites. The IR spectra confirmed the lone pair donating or coordinating sites. The elemental analysis confirmed the stoichiometry. The bathochromic shift with an increase in the optical density in the UV-Visible range indicated that the compound and its central metal ion hold uniform electronic charge distribution. The electrochemical results indicated a quasi-reversible (neither completely reversible nor completely irreversible) oxidation of the complex to its uranium(V) product at the platinum working electrode. The quasi-reversible process shows a comparatively slow electron transfer (ET) rate with the heterogeneous electron transfer rate constant ‘ks’ (3.4 ×  10–4 cm s-1) at 50 mV s-1 and 305 ± 0.5 K. The kinetics such as diffusion and charge transfer lead the reaction with an ECE (electrochemical–chemical–electrochemical) mechanism. The thermodynamic parameters of activation such as ΔH*; 4.257 kJ mol–1, ΔS*; -2.519 × 10–3 J mol–1 K–1 and ΔG* 4.26 kJ mol–1 helped to propose an associative mechanism of the electron transfer at the platinum working electrode.                     KEY WORDS: Uranium, Histidine, Spectroscopy, Electrochemistry, Kinetics   Bull. Chem. Soc. Ethiop. 2020, 34(3), 557-569.  DOI: https://dx.doi.org/10.4314/bcse.v34i3.1

Microwave measurement techniques for wearable antennas

This research is germane to the area of on-body antennas and the characterisation of antennas in close proximity to biological matter. The ranges of frequencies discussed are currently popular for mobile communications, namely 0.9GHz to 6GHz with spot frequencies of GSM900, GSM1800 and WiFi2.5GHz. Particular attention is given to the elimination of errors in measurement. This is achieved by the characterisation of an anechoic chamber; a study of the effects of cables; a study of the interaction of surface currents and the human body; a study of tissue simulating liquid; the design of a simple body phantom; the characterisation of the on-body channel for human males in wet and dry clothing and a comparison of perturbation on antennas close to humans and a phantom.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

SoK: Making Sense of Censorship Resistance Systems

An increasing number of countries implement Internet censorship at different scales and for a variety of reasons. Several censorship resistance systems (CRSs) have emerged to help bypass such blocks. The diversity of the censor’s attack landscape has led to an arms race, leading to a dramatic speed of evolution of CRSs. The inherent complexity of CRSs and the breadth of work in this area makes it hard to contextualize the censor’s capabilities and censorship resistance strategies. To address these challenges, we conducted a comprehensive survey of CRSs-deployed tools as well as those discussed in academic literature-to systematize censorship resistance systems by their threat model and corresponding defenses. To this end, we first sketch a comprehensive attack model to set out the censor’s capabilities, coupled with discussion on the scope of censorship, and the dynamics that influence the censor’s decision. Next, we present an evaluation framework to systematize censorship resistance systems by their security, privacy, performance and deployability properties, and show how these systems map to the attack model. We do this for each of the functional phases that we identify for censorship resistance systems: communication establishment, which involves distribution and retrieval of information necessary for a client to join the censorship resistance system; and conversation, where actual exchange of information takes place. Our evaluation leads us to identify gaps in the literature, question the assumptions at play, and explore possible mitigations

The effects of water on an on-body monopole diversity antenna pair at 1800MHz

This paper presents the effect of water on a pair of 1.8GHz on-body diversity monopole antennas mounted on the forearm of a sitting male static volunteer. Application of a water layer to the forearm was seen to both reduce efficiency and increase directivity leading to a slight overall increase in gain. Increased gain was shown to increase antenna correlation thereby reducing diversity gain in the antenna pair

A study of perturbations in linear and circular polarized antennas in close proximity to the human body and a dielectric liquid filled phantom at 1.8 GHz

In the design and synthesis of wearable antennas isolation distance from the body is a critical parameter. This paper deals with the comparison of perturbations caused to the matching of simple linear and circular polarized patch antennas due to the close proximity of a human torso and rectangular box phantom filled with muscle simulating liquid at 1.8GHz. The isolated variable is return loss (S11). Results show that both linear and circularly polarized antennas produce an optimal return loss closer to the surface of a typical phantom than the back of a human volunteer

A study of perturbations in linear and circular polarized antennas in close proximity to the human body and dielectric liquid filled rectangular and a cylindrical phantom at 1.8 GHz

In the design and synthesis of wearable antennas isolation distance from the body is a critical parameter. This paper deals with the comparison of perturbations caused to the matching of simple linear and circular polarized patch antennas due to the close proximity of a human torso and rectangular box and cylindrical phantoms filled with muscle simulating liquid at 1.8GHz. The isolated variable is return loss, S11(dB). Results show that at these frequencies a cylindrical phantom resembles the body more closely than a rectangular phantom

BREEDING HIGH YIELDING DESI CHICKPEA (CICER ARIETINUM L.) GENOTYPES FOR THE AGRO-CLIMATIC CONDITIONS OF NWFP

Abstract Seeds of the 2 local desi chickpea varieties viz., Pb-91and C-44 were irradiated through gamma rays at 200 and 300 Gy doses during the year 2000. The M 1 to M 4 generations were raised fro