Lattice study of the Coleman--Weinberg mass in the SU(2)-Higgs model

Radiative symmetry breaking is a well known phenomenon in perturbation theory. We study the problem in a non-perturbative framework, i.e. lattice simulations. The example of the bosonic sector of the SU(2)-Higgs model is considered. We determine the minimal scalar mass which turns out to be higher than the mass value given by 1-loop continuum perturbation theory.Comment: Contribution to ICHEP-02, Amsterdam, 24-31 July 2002, 2 pages, 1 figur

Electrochemical study of different membrane materials for the fabrication of stable, reproducible and reusable reference electrode

© 2020 Fabrication of stable, reproducible and reusable reference electrodes for low energy and high-temperature steam splitting is of great interest for hydrogen fuel production without anthropogenic carbon dioxide (CO2) emission. This study has been conducted for the detection of suitable material for the fabrication of novel reference electrode. In the present scenario, this research is designed to fabricate a novel nickel reference electrode by using operating conditions of eutectic molten hydroxide (NaOH-KOH, 49–51 mol%) at temperature 300 °C in an ion-conducting membrane of alumina and mullite tube. Afterwards, the designed nickel reference electrode has been examined for its reusability and stability by using electrochemical technique and cyclic voltammetry. Five scans of cyclic voltammetry are performed for both membrane fabricated reference electrode. A slight positive shift in oxidation peaks is observed for mullite membrane electrode (64 mV from scan 1 to 5). The stability measurements are noted by changing the scan rate between 50 and 150 mV s−1. Furthermore, the results show that the Ni/Ni(OH)2 reference electrode covered with a mullite membrane is stable and reusable at 300 °C temperature without any deterioration. The stability and reusability of prepared nickel reference electrode covered by mullite tube in the eutectic molten hydroxide were up to 9 days to carry out an electrochemical investigation, while for alumina tube reference electrode the stability and reliability were up to 3 days. The internal electrolytic material and ionic conductance can play an important role for future studies with this reference electrode along with optimisation of temperature and scan rate parameters

Enhancing hydrogen production from steam electrolysis in molten hydroxides via selection of non-precious metal electrodes

© 2020 Hydrogen Energy Publications LLC There are still gaps in the field of reference electrode that is needed to assist electrolysis in high temperature electrolytes (e.g. molten hydroxides) for H2 gas production. This research aims to fill the gaps by preparing Ni/Ni(OH)2 reference electrode and more importantly testing its effectiveness against important performance factors including; ion conducting membrane (e.g. mullite tubes), internal electrolyte composition, working temperature and electrochemical control (e.g. potential scan rate). Then, this reference electrode was used to study the electrocatalytic activity various cheaper working electrode materials including; stainless steel (St.st), Ni, Mo and Ag in comparison with Pt by the means of chronoamperometry and voltammetry. The effect of introducing steam into electrolyte (eutectic mixture of NaOH and KOH) on the electrocatalytic activity of these working electrodes was also studied. It was observed that the potential of hydrogen evolution with different working electrodes followed an order as; Pt > Ni > St. st > Ag > Mo (positive to negative). The performance of each working electrode was confirmed through chronoamperometry for hydrogen evolution at a constant potential of −0.7 V. It was also found in cyclic voltammetry and confirmed by chronoamperometry that the introduction of steam was apparent as increasing the current density at cathodic limit for hydrogen evolution. This study could help to develop non-precious metal electrodes for the production of hydrogen fuel. In future, there will be a potential in the threshold concentration of steam for H2 gas production

Electrochemical investigation of novel reference electrode Ni/Ni(OH)₂ in comparison with silver and platinum inert quasi-reference electrodes for electrolysis in eutectic molten hydroxide

An efficient and green energy carrier hydrogen (H2) generation via water splitting reaction has become a major area of focus to meet the demand of clean and sustainable energy sources. In this research, the splitting steam via eutectic molten hydroxide (NaOH–KOH; 49–51 mol%) electrolysis for hydrogen gas production has been electrochemically investigated at 250–300 °C. Three types of reference electrodes such as a high-temperature mullite membrane Ni/Ni(OH)2, quasi-silver and quasi-platinum types were used. The primary purpose of this electrode investigation was to find a suitable, stable, reproducible and reusable reference electrode in a molten hydroxide electrolyte. Cyclic voltammetry was performed to examine the effect on reaction kinetics and stability to control the working electrode at different scan rate and molten salt temperature. The effect of introducing water to the eutectic molten hydroxide via the Ar gas stream was also investigated. When the potential scan rate was changed from 50 to 150 mV s−1, the reduction current for the platinum wire working electrode was not changed with newly prepared nickel reference electrode that designates its stability and reproducibility. Furthermore, increasing the operating temperature of molten hydroxides from 250 to 300 °C the reduction potential of the prepared nickel reference electrode is slightly positive shifted about 0.02 V. This suggests that it has good stability with temperature variations. The prepared nickel and Pt reference electrode exhibited stable and reliable cyclic voltammetry results with and without the presence of steam in the eutectic molten hydroxide while Ag reference electrode exposed positive shifts of up to 0.1 V in the reduction potential. The designed reference electrode had a more stable and effective performance towards controlling the platinum working electrode as compared to the other quasi-reference electrodes. Consequently, splitting steam via molten hydroxides for hydrogen has shown a promising alternative to current technology for hydrogen production that can be used for thermal and electricity generation

Adolescent brain cognitive development (ABCD) study: Overview of substance use assessment methods.

One of the objectives of the Adolescent Brain Cognitive Development (ABCD) Study (https://abcdstudy.org/) is to establish a national longitudinal cohort of 9 and 10 year olds that will be followed for 10 years in order to prospectively study the risk and protective factors influencing substance use and its consequences, examine the impact of substance use on neurocognitive, health and psychosocial outcomes, and to understand the relationship between substance use and psychopathology. This article provides an overview of the ABCD Study Substance Use Workgroup, provides the goals for the workgroup, rationale for the substance use battery, and includes details on the substance use module methods and measurement tools used during baseline, 6-month and 1-year follow-up assessment time-points. Prospective, longitudinal assessment of these substance use domains over a period of ten years in a nationwide sample of youth presents an unprecedented opportunity to further understand the timing and interactive relationships between substance use and neurocognitive, health, and psychopathology outcomes in youth living in the United States

Electrochemical production of sustainable hydrocarbon fuels from CO2 co-electrolysis in eutectic molten melts

Because of the heavy reliance of people on limited fossil fuels as energy resources, global warming has increased to severe levels because of huge CO2 emission into the atmosphere. To mitigate this situation, a green method is presented here for the conversion of CO2/H2O into sustainable hydrocarbon fuels via electrolysis in eutectic molten salts [(KCl-LiCl; 41:59 mol %), (LiOH-NaOH; 27:73 mol %), (KOH-NaOH; 50:50 mol %), and (Li2CO3-Na2CO3-K2CO3; 43.5:31.5:25 mol %)] under the conditions of 1.5-2 V and 225-475 °C depending on the molten electrolyte used. Gas chromatography (GC) and GC-mass spectrometry (MS) techniques were employed to analyze the content of gaseous products. The electrolysis results in hydrocarbon production with maximum 59.30, 87.70, and 99% Faraday efficiencies in the case of molten chloride, molten hydroxide, and molten carbonate electrolytes under the temperatures of 375, 275, and 425 °C, respectively. GC with a flame-ionization detector and a thermal conductivity detector and GC-MS analysis confirmed that H2 and CH4 were the main products in the case of molten chlorides and hydroxides at an applied voltage of 2 V, while longer-chain hydrocarbons (>C1) were obtained only in molten carbonates at 1.5 V. In this way, electricity is transformed into chemical energy. The heating values obtained from the produced hydrocarbon fuels are satisfactory for further application. The practice of using molten salts could be a promising and encouraging technology for further fundamental investigation of sustainable hydrocarbon fuel formation with more product concentrations because of their fast electrolytic conversion rate without the use of a catalyst

Mixed convective eyring-powell ferro magnetic nanofluid flow suspension towards a stretching surface with buoyancy effects through numerical analysis

This article examines the impact of buoyancy on the magnetic Eyring-Powell nanofluid flow toward a stretching surface. Coupled similarity equations are created from the governing flow equations. For the particular instance of pure fluid flow, the numerically computed self-similar results are matched with the available literature and found to be in acceptable harmony. The shooting approach was used to arrive at numerical computations to the constitutive ordinary differential equations. The impacts of different fluid flow parameters, nano concentration parameters and heat transfer, are shown graphically for both aiding and opposing flows. It has been discovered that for both aiding and opposing problems, the skin friction is less affected by the buoyant force brought on by temperature differences. Under buoyancy, the rate of heat transfer increments for aiding flow problem while it declines for opposing flow

Vacuum Stability, Perturbativity, and Scalar Singlet Dark Matter

We analyze the one-loop vacuum stability and perturbativity bounds on a singlet extension of the Standard Model (SM) scalar sector containing a scalar dark matter candidate. We show that the presence of the singlet-doublet quartic interaction relaxes the vacuum stability lower bound on the SM Higgs mass as a function of the cutoff and lowers the corresponding upper bound based on perturbativity considerations. We also find that vacuum stability requirements may place a lower bound on the singlet dark matter mass for given singlet quartic self coupling, leading to restrictions on the parameter space consistent with the observed relic density. We argue that discovery of a light singlet scalar dark matter particle could provide indirect information on the singlet quartic self-coupling.Comment: 25 pages, 10 figures; v2 - fixed minor typos; v3 - added to text discussions of other references, changed coloring of figures for easier black and white viewin

Thermal and kinetic analysis of diverse biomass fuels under different reaction environment: A way forward to renewable energy sources

This study investigates the thermal and kinetic analysis of six diverse biomass fuels, in order to provide valuable information for power and energy generation. Pyrolytic, combustion and kinetic analyses of barley straw, miscanthus, waste wood, wheat straw, short rotation coppicing (SRC) willow and wood pellet were examined by non-isothermal thermogravimetry analyser (TGA), differential thermogravimetric (DTG) and differential scanning calorimetry (DSC) techniques. Biomass fuels were thermally degraded under N2, air, CO2 and the selected oxy-fuel (30% O2/70% CO2) reaction environments. The thermal degradation under inert N2 and CO2 atmospheres showed an almost identical rate of weight loss (R), reactivity (RM × 103) and activation energy (Ea) profiles. Similar profiles for R, RM and Ea were observed for the environments under air (21% O2/79% N2) and the oxy-fuel combustion. Results indicated that the thermal decomposition rate for biomass fuels in an oxidising condition was faster than in an inert atmosphere, favourable effect on thermal degradation of biomass fuels was observed when oxygen content increased from 21 to 30%. Higher activation energies with lower reactivity were observed for the biomass fuels that have low cellulosic contents as compared to the other fuels. Regression analysis confirmed that the reaction order 0.5 modelled fitted well for all biomass samples. All these findings will provide valuable information and promote the advancement of future researches in this field