Diamond nanostructured devices for chemical sensing applications

Research in the area of CVD single crystal diamond plates of which only recently has been made commercially available saw significant advancements during the last decade. In parallel to that, detonation nanodiamond (DND) particles also now widely made accessible for requisition are provoking a lot of scientific investigations. The remarkable properties of diamond including its extreme hardness, low coefficient of friction, chemical inertness, biocompatibility, high thermal conductivity, optical transparency and semiconducting properties make it attractive for a number of applications, among which electronic and micro electrical-mechanical systems devices for chemical and biological applications are few of the key areas. A detailed knowledge of diamond devices at the prototypical stage is therefore critical. The work carried out encapsulated in this thesis describes the employment of the nanometer-scale diamond structures for the design, fabrication and testing of electronic devices and micro electrical-mechanical system (MEMS) structures for chemical sensing applications. Two major approaches are used to achieve engineering novelty. The first type being devices based on single crystal diamond substrates, which include state of the art δ-doped single crystal diamond Ion Sensitive Field Effect Transistor with an intrinsic layer capping the delta-doped layer for pH sensing and the fabrication and characterization of a triangular-face single crystal diamond MEMS. A comprehensive set of characterisations was systematically performed on the delta ISFET devices. Cyclic Voltammetry has been used to determine the devices’ potential window determining the limits of the applied potential for the Current-Voltage measurements. In solutions of different pH levels, an improved sensitivity of 55mV/pH compared to cap-less design in a previous study is taken as the salient figure of merit. Electrochemical Impedance Spectroscopy sheds some light on device performance in terms of flatband voltages and conduction pathways through circuit modelling. Improved ISFET characteristics such as lower flat-band voltage at 3.74V, simpler conduction paths and drain current saturation onsets show the chosen design is correct and advances delta-doped diamond ISFET research and development work. For the single crystal diamond cantilever, the theoretical modelling supports the triangular-face design to be a better option, generating 3x greater deflections in relation to the conventional rectangular-face design, when operated as a static mode sensor. Based on experimental characterisation methods such as Raman and Energy Dispersive Spectroscopy, the focusedion beam only milling technique inflicts minimum damage to the beam structure. In the second approach, a novel hybrid device idea was conceived and implemented using off-the-shelf silicon ISFETs and cantilevers with a coat of nanodiamond particles on the ‘active area’ surfaces of the respective devices. These nanodiamond-coated silicon devices exhibit high sensitivity for tracing threat signatures such as explosive precursors and analogues with the former in both liquid and vapour medium, and the latter in the vapour phase. The nanodiamond-gated ISFET shows a voltage response of a commendable maximum voltage shift of ~90 mV throughout 0 to 0.1M concentration range of NO2 - and ClO3 - solutions. In the vapour phase detecting 2,4-DNT, a sensitivity of ~20mV/0.4ppm is observed. The nanodiamond-coated silicon cantilever demonstrates a performance advantage of 7.4 Hz/ppb to 1.7 Hz/ppb in a previous study. Fourier Transform Infra-red spectroscopy was carried out on the nanodiamond surfaces hosted by potassium bromide (KBr) discs to ascertain the vapour chemisorption. With the fabrication technique simplified, commercialisation of these proof-of-concept devices should be less time consuming thus enabling quicker deployment of diamond-based surface sensing technology

Shareholders' under the company law of the state of Kuwait: An evaluation of existing laws and proposals for reform

This thesis is an extensive study which concentrates on the shareholders' equity rights in joint stock companies under the Company Law of the State of Kuwait No. 15/1960. At the same time the thesis looks at the companies law of other counties, mainly at the UK Companies Act. The aim of examining foreign company laws is so that these might be used to improve company law in Kuwait. The main purpose of this thesis is to define the rights and role of shareholders. The thesis also attempts to identify the position, role and powers of the body of shareholders in joint stock companies by dedicating a chapter focusing on the topic of company theory. This study is divided into a number of chapters. The first chapter is an introductory chapter which concentrates on the legal system and the kinds of companies in Kuwait. The second chapter focuses on the theory of the company and nature of shareholders roles according to such a theory. The third chapter focuses on the definition of shares and shareholders in joint stock companies. The fourth chapter deals with shareholders financial rights. Chapter five is devoted to a discussion of shareholders' right to knowledge of what took place and is going on in the company and the board's duty to disclose all facts and details about the company's affairs. The sixth chapter concentrates on the auditors' role. The auditor acts on behalf of the shareholders to verify the credibility of the disclosed information and the validity and soundness of directors' acts. Chapter seven is concerned with shareholders' rights at the general meeting. Chapter eight deals with shareholders remedies. The thesis concludes with some proposals for reform of the Kuwait Company Law

Potential of biogas production from food waste in a uniquely designed reactor under lab conditions

An original digester design is adopted in building a lab scale 20 L biogas plant. The novelty is the digester has a recycling line apart from other inclusions (inlet, outlet, gasline etc.) including water seal. Initially cow dung (inoculum) was added. After initial gas production, cow dung in the digester was co digested with food waste. Main ingredients of the food waste included rice, vegetable peelings, cucumber, bitter gourd etc., This waste had slightly higher solids and volatile solids (9.3% and 94.9%) content compared to cow dung (8.5% and 93.1%). The biogas volume was determined by measuring the downward movement of the water line and calculating the volume of the water that was displaced by gas. The loading rate of the digester in terms of Total solids was 16.6 kg/ (m3 *day). The amount of biogas production starting from the 16th to the 23rd day was 6.7L. This biogas did not burn. The failure to burn was probably due to low methane and a high carbon dioxide concentration in the biogas. After the 23rd day 650 mL biogas was ignited using a match stick. The total biogas yield recorded was 68.50L for a period of 60 days. The lab temperature was between 30- 340C. Maximum microbial counts of 6.21*104 colonies / mL were observed during the peak of biogas production. The phosphate content was recorded 1.027 mg/100g (slurry content) on the 60th day. The volatile solids finally reduced to 81.66% of total solids. This volatile solids reduction/destruction/ leads to conversion of biogas. The volume of biogas produced from the amount volatile solids destroyed calculated using the ideal gas law was 51Litres. In an Indian scenario, food waste can become a good feedstock for biogas production at Indian households instead of going to the dump yards or being burnt along with plastic/polythene cover. Of the different types of organic wastes available food waste holds highest potential of economic exploitation as it contains high amount of carbon in the volatile solids that can be converted into biogas. The widespread implementation of biogas digesters in urban areas would contribute to the solution of the problems of urban sanitation energy supply and mitigation of green house gases

Enhanced T-odd P-odd Electromagnetic Moments in Reflection Asymmetric Nuclei

Collective P- and T- odd moments produced by parity and time invariance violating forces in reflection asymmetric nuclei are considered. The enhanced collective Schiff, electric dipole and octupole moments appear due to the mixing of rotational levels of opposite parity. These moments can exceed single-particle moments by more than two orders of magnitude. The enhancement is due to the collective nature of the intrinsic moments and the small energy separation between members of parity doublets. In turn these nuclear moments induce enhanced T- and P- odd effects in atoms and molecules. First a simple estimate is given and then a detailed theoretical treatment of the collective T-, P- odd electric moments in reflection asymmetric, odd-mass nuclei is presented and various corrections evaluated. Calculations are performed for octupole deformed long-lived odd-mass isotopes of Rn, Fr, Ra, Ac and Pa and the corresponding atoms. Experiments with such atoms may improve substantially the limits on time reversal violation.Comment: 28 pages, Revte

Pharmacognostic and Physico chemical standardization of Cinchona officinalis Linn.f

 Cinchona officinalis Linn.f. is commonly known as Crown bark in English belongs to family Rubiaceae. Stem bark of C. officinalis have profound application in homeopathy. Aim of the present study is to standardizing C. Officinalis mother tinctures by taking from three different sources [Dr.D.P.Rastogi, CRI (H) Noida (A), two from market (B, C)] for pharmacognostic, physio chemical studies and comparative analysis for authentication of drug

Effect of the proton irradiation on the thermally activated flux flow in superconducting SmBCO coated conductors

We investigate changes in the vortex pinning mechanism caused by proton irradiation through the measurement of the in-plane electrical resistivity for H//c in a pristine and two proton-irradiated (total doses of 1 × 1015 and 1 × 1016 cm−2) SmBa2Cu3O7-δ (SmBCO) superconducting tapes. Even though proton irradiation has no effect on the critical temperature (Tc), the resulting artificial point defect causes an increase in normal state electrical resistivity. The electrical resistivity data around Tc shows no evidence of a phase transition to the vortex glass state but only broadens with increasing magnetic field due to the vortex depinning in the vortex liquid state. The vortex depinning is well interpreted by a thermally activated flux flow model in which the activation energy shows a nonlinear temperature change U(T,H)=U0(H)(1−T/Tc)q (q = 2). The field dependence of activation energy shows a U0~H−α with larger exponents above 4 T. This field dependence is mainly due to correlated disorders in pristine sample and artificially created point defects in irradiated samples. Compared with the vortex pinning due to correlated disorders, the vortex pinning due to the appropriate amount of point defects reduces the magnitude of Uo(H) in the low magnetic field region and slowly reduces Uo(H) in high magnetic fields. © 2020, The Author(s).1

Antineutrinos from Earth: A reference model and its uncertainties

We predict geoneutrino fluxes in a reference model based on a detailed description of Earth's crust and mantle and using the best available information on the abundances of uranium, thorium, and potassium inside Earth's layers. We estimate the uncertainties of fluxes corresponding to the uncertainties of the element abundances. In addition to distance integrated fluxes, we also provide the differential fluxes as a function of distance from several sites of experimental interest. Event yields at several locations are estimated and their dependence on the neutrino oscillation parameters is discussed. At Kamioka we predict N(U+Th)=35 +- 6 events for 10^{32} proton yr and 100% efficiency assuming sin^2(2theta)=0.863 and delta m^2 = 7.3 X 10^{-5} eV^2. The maximal prediction is 55 events, obtained in a model with fully radiogenic production of the terrestrial heat flow.Comment: 24 pages, ReVTeX4, plus 7 postscript figures; minor formal changes to match version to be published in PR

Understanding Volumetric Water Storage in Monsoonal Wetlands of Northeastern Bangladesh

The volume of water stored in seasonal wetlands is a fundamental but difficult to measure variable for developing a physical understanding of wetland behavior. For seasonal wetlands that are a major source of water for rice and fish production, this physical understanding is key to planning for water-food security and ecosystem services. This study quantified variations in volumetric storage for the numerous seasonal wetlands of northeastern Bangladesh, locally known as “haors.” These haors receive transboundary runoff from densely vegetated and mountainous terrain in India and face persistent monsoonal cloud cover as they become full. We estimated volumetric storage for 13 haors by using extensive remote sensing data on water surface extent and elevation that was complemented with citizen-contributed gauge data. Assuming a trapezoidal bathymetry, an area-volume relationship was developed for selected haors. This relationship was assumed to be valid for extrapolating volumetric estimations over all the haors in the region. Results suggested that as haors get filled with the onset of monsoon rains, total estimated storage relative to the lowest observable level varied from 6.5 (±0.4) km3 in May to 30.9 (±2.0) km3 in July (peak of monsoon). Choosing a rectangular bathymetry can lead to 47% higher estimates compared to trapezoidal cross section. Estimating this intra-annual/interannual increase in storage is important for the region to plan water management policies that balance the human and ecosystem needs. Our analytical approach has potential for application to wetlands worldwide in light of the upcoming Surface Water and Ocean Topography (SWOT) mission

Search for a W' boson decaying to a bottom quark and a top quark in pp collisions at sqrt(s) = 7 TeV

Results are presented from a search for a W' boson using a dataset corresponding to 5.0 inverse femtobarns of integrated luminosity collected during 2011 by the CMS experiment at the LHC in pp collisions at sqrt(s)=7 TeV. The W' boson is modeled as a heavy W boson, but different scenarios for the couplings to fermions are considered, involving both left-handed and right-handed chiral projections of the fermions, as well as an arbitrary mixture of the two. The search is performed in the decay channel W' to t b, leading to a final state signature with a single lepton (e, mu), missing transverse energy, and jets, at least one of which is tagged as a b-jet. A W' boson that couples to fermions with the same coupling constant as the W, but to the right-handed rather than left-handed chiral projections, is excluded for masses below 1.85 TeV at the 95% confidence level. For the first time using LHC data, constraints on the W' gauge coupling for a set of left- and right-handed coupling combinations have been placed. These results represent a significant improvement over previously published limits.Comment: Submitted to Physics Letters B. Replaced with version publishe