Enhanced superconducting properties of rare-earth oxides and graphene oxide added MgB₂

In this paper, the effects of addition of (i) graphene oxide (GO), (ii) a series of rare-earth (RE, RE = La, Sm, Eu, Gd, Tb and Ho) oxides (REO) and (iii) a mixture of GO and rare-earth oxides (GO + REO) on the superconducting properties of MgB₂, have been studied with the help of electrical transport and magnetic measurements. All the samples have been prepared following the standard solid-state reaction route. We have used an optimum value of 1 wt% REO and 3 wt% GO for addition on the basis of previous studies. X-ray diffraction studies confirm the formation of hexagonal crystal structure (space group P6/mmm) of MgB₂ with small amounts of REBx (x = 4 and 6) and MgO impurity phases in all the synthesized samples. We observe that the critical current density, Jc and upper critical field Hc2(0) improve significantly in the REO-added and GO-added samples with no significant change in critical temperature, Tc. A substantial enhancement in Jc(H) and Hc2(0) is observed with the GO + REO addition in MgB₂. The different flux pinning mechanisms in all the samples are studied and it is found that the point pinning is the dominant mechanism in the GO-added samples and grain boundary pinning is the dominant one in the REO added samples. We have seen the combined effect of both types of flux pinning mechanisms in GO + REO added MgB₂

Cost-Benefit Analysis of a Redundant System with Server having Refreshment Facility Subject to Inspection

In this paper two units cold standby system has been discussed with the facility that server inspect the failed unit before repair/replacement of the unit and server may allow to take refreshment whenever needed. The operative unit may fail directly from normal mode and the cold standby unit may be failed owing to remain unused for a longer period of time. There is single server who serves the dual purpose of inspection and repair immediately whenever required. Also, after having refreshment the server may eventually perform the better service efficiently. The time to take refreshment and repair activity follows negative exponential distribution whereas the distributions of unit failure and server failure are taken as arbitrary with different probability density functions. The expressions of various stochastic measures are analyzed in steady state using semi-Markov process and regenerative point technique. The graphs are sketched for arbitrary values of the parameters to delineate the behavior of some important performance measures to check the efficacy of the system model under such situations

Enhanced production of poly (3-hydroxybutyrate-co-4-hydroxybutyrate) copolymer with manipulated variables and its properties

Cupriavidus sp. USMAA1020, a local isolate was able to biosynthesis poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB)] copolymer with various 4HB precursors as the sole carbon source. Manipulation of the culture conditions such as cell concentration, phosphate ratio and culture aeration significantly affected the synthesis of P(3HB-co-4HB) copolymer and 4HB composition. P(3HB-co-4HB) copolymer with 4HB compositions ranging from 23 to 75 mol% 4HB with various mechanical and thermal properties were successfully produced by varying the medium aeration. The physical and mechanical properties of P(3HB-co-4HB) copolymers were characterized by NMR spectroscopy, gel-permeation chromatography, tensile test, and differential scanning calorimetry. The number-average molecular weights (M (n)) of copolymers ranged from 260 x 10(3) to 590 x 10(3)Da, and the polydispersities (M (w)/M (n)) were between 1.8 and 3.0. Increases in the 4HB composition lowered the molecular weight of these copolymers. In addition, the increase in 4HB composition affected the randomness of copolymer, melting temperature (T (m)), glass transition temperature (T (g)), tensile strength, and elongation to break. Enzymatic degradation of P(3HB-co-4HB) films with an extracellular depolymerase from Ochrobactrum sp. DP5 showed that the degradation rate increased proportionally with time as the 4HB fraction increased from 17 to 50 mol% but were much lower with higher 4HB fraction. Degradation of P(3HB-co-4HB) films with lipase from Chromobacterium viscosum exhibited highest degradation rate at 75 mol% 4HB. The biocompatibility of P(3HB-co-4HB) copolymers were evaluated and these copolymers have been shown to support the growth and proliferation of fibroblast cells

Temperature-dependent transformation of the magnetic excitation spectrum on approaching superconductivity in Fe1-x (Ni/Cu)x Te0.5 Se0.5

Spin excitations are one of the top candidates for mediating electron pairing in unconventional superconductors. Their coupling to superconductivity is evident in a large number of systems, by the observation of an abrupt redistribution of magnetic spectral weight at the superconducting transition temperature, Tc, for energies comparable to the superconducting gap. Here we report inelastic neutron scattering measurements on Fe-based superconductors, Fe1-x (Ni/Cu)x Te0.5 Se0.5, that emphasize an additional signature. The overall shape of the low energy magnetic dispersion changes from two incommensurate vertical columns at T >> Tc to a distinctly different U-shaped dispersion at low temperature. Importantly, this spectral reconstruction is apparent for temperature up to ~3Tc. If the magnetic excitations are involved in the pairing mechanism, their surprising modification on the approach to Tc demonstrates that strong interactions are involved

Profit Analysis of a Two Unit Cold Standby System Operating Under Different Weather Conditions Subject t o Inspection

A system, or unit, is said to be working under normal weather conditions if the system is working under prescribed conditions as defined/stated by the definition of reliability of system/unit, otherwise the system is said to be working in abnormal weather conditions. For example, if a car with the capacity for five persons is carrying more than five persons, it will be said to be working under abnormal weather conditions. Another example, if a hydraulic machine having the capacity to lift a maximum weight of 500 tons is lifting a weight of 600 tons, then the machine is working under abnormal weather conditions. Hence, in this situation, work done by the machine is out of its capacity and the machine is working in abnormal weather conditions. If the machine is working within the capacity of the stated conditions, it is said to be working in normal weather conditions. The main purpose of this paper is to analyze the profit of a two-unit system called the standby system that is working under different weather conditions in an inspection facility. There is a single perfect server who visits the system immediately whenever required. A server inspects the unit before repair/replacement of the failed unit. All the mechanical activities done by the server are only possible during normal weather conditions. There are two possibilities after inspection of the unit; either repair of the unit is feasible or not feasible. If repair of the unit is not feasible, then the unit will be replaced immediately by a new unit. Otherwise, the repaired unit works as a new unit. The operative unit undergoes preventive maintenance after a specific (maximum) operation time. All random variables are statistically independent. The failure rate and the rate by which the system undergoes for preventive maintenance are constant whereas the inspection rate, repair rate, and maintenance rate follow negative exponential distributions. The expressions for several reliability measures are derived in steady state conditions using the regenerative point technique and semi-Markov process. The graphical behavior of MTSF, availability and profit function, has been depicted with respect to preventive maintenance rate for arbitrary values of other parameters and costs

Willingness of Coconut Growers to Join Farmer Producer Companies in Western Tamil Nadu–An Exploratory Study

Coconut, a versatile crop called as ‘Kalpaviriksha’ – A tree of Heaven. India, with the rich biodiversity of coconut, is the largest producer with 33.02 percent share or 22167 million nuts of the world's largest production of 67128 million nuts. But still, the farmers facing difficulties in marketing coconut. The constraints pertaining to the marketing of coconut were lack of government procurement system, lack of co-operative marketing, lack of proper market information, monopoly of market intermediaries, fluctuation in market price, and high commission among intermediaries were the major problems faced by the coconut growers.  This study analyses the perception and preference of coconut farmers in joining coconut producer companies in the Western Tamil Nadu. Descriptive analysis and Garret raking technique has been used and concluded that price provided by the FPC was good and fair enough compared to the market price, which was the major reason for joining the FPC and lack of awareness on benefits obtained, share capital contribution requirement, and benefits not distributed evenly are the major problem in not joining the FPCs

Structural identification of two differently coordinated heptamolybdate ligands in a hexamagnesium compound

517-525Dissolution of freshly prepared molybdenum trioxide in hot aqueous magnesium carbonate followed by crystallization results in the formation of an all-inorganic heptamolybdate compound viz. [Mg(H2O)6]3[Mg(H2O)5(Mo7O24)][(H2O)5Mg (µ2-Mo7O24)Mg(H2O)5]∙6H2O (1). The crystal structure, spectral characteristics, thermal and electrochemical properties of 1 are reported. Compound 1, which crystallizes in the acentric polar space group Cc, contains six unique Mg(II) ions. The two crystallographically independent heptamolybdate anions function as a monodentate (η1) and µ2-bridging bidentate ligand, respectively, forming the anionic [Mg(H2O)5(Mo7O24)]4− and [(H2O)5Mg(µ2-Mo7O24)Mg(H2O)5]2− species, which are charge balanced by three unique hexaaquamagnesium(II) cations. The electrochemical and conductivity studies of 1 reveal the presence of [Mg(H2O)6]2+ cations and uncoordinated (Mo7O24)6− anions in solution. Thermal decomposition of 1 leads to the formation of Mg2Mo3O11 via Mg6Mo14O48 and 3Mg2Mo3O11∙5MoO3

Physicochemical Characterization of Passive Films and Corrosion Layers by Differential Admittance and Photocurrent Spectroscopy

Two different electrochemical techniques, differential admittance and photocurrent spectroscopy, for the characterization of electronic and solid state properties of passive films and corrosion layers are described and critically evaluated. In order to get information on the electronic properties of passive film and corrosion layers as well as the necessary information to locate the characteristic energy levels of the passive film/electrolyte junction like: flat band potential (Ufb), conduction band edge (EC) or valence band edge (EV), a wide use of Mott-Schottky plots is usually reported in corrosion science and passivity studies. It has been shown, in several papers, that the use of simple M-S theory to get information on the electronic properties and energy levels location at the film/electrolyte interface can be seriously misleading and/or conflicting with the physical basis underlying the M-S theory. A critical appraisal of this approach to the study of very thin and thick anodic passive film grown on base-metals (Cr, Ni, Fe, SS etc..) or on valve metals (Ta, Nb, W etc..) is reported in this work, together with possible alternative approach to overcome some of the mentioned inconsistencies. At this aim the theory of amorphous semiconductor Schottky barrier, introduced several years ago in the study of passive film/electrolyte junction, is reviewed by taking into account some of the more recent results obtained by the present authors. Future developments of the theory appears necessary to get more exact quantitative information on the electronic properties of passive films, specially in the case of very thin film like those formed on base metals and their alloys. The second technique described in this chapter, devoted to the physico-chemical characterization of passive film and corrosion layers, is a more recent technique based on the analysis of the photo-electrochemical answer of passive film/electrolyte junction under illumination with photons having suitable energy. Such a technique usually referred to as Photocurrent Spectroscopy (PCS) has been developed on the basis of the large research effort carried out by several groups in the 1970’s and aimed to investigate the possible conversion of solar energy by means of electrochemical cells. In this work the fundamentals of semiconductor/electrolyte junctions under illumination will be highlighted both for crystalline and amorphous materials. The role of amorphous nature and film thickness on the photo-electrochemical answer of passive film/solution interface is reviewed as well the use of PCS for quantitative analysis of the film composition based on a semi-empirical correlation between optical band gap and difference of electronegativity of film constituents previously suggested by the present authors. In this frame the results of PCS studies on valve metal oxides and valve metal mixed oxides will be discussed in order to show the validity of the proposed method. The results of PCS studies aimed to get information on passive film composition and carried out by different authors on base metals (Fe, Cr, Ni) and their alloys, including stainless steel, will be also compared with compositional analysis carried out by well-established surface analysis techniques

Optimization of growth media components for polyhydroxyalkanoate (PHA) production from organic acids by Ralstonia eutropha

We employed systematic mixture analysis to determine optimal levels of acetate, propionate, and butyrate for cell growth and polyhydroxyalkanoate (PHA) production by Ralstonia eutropha H16. Butyrate was the preferred acid for robust cell growth and high PHA production. The 3-hydroxyvalerate content in the resulting PHA depended on the proportion of propionate initially present in the growth medium. The proportion of acetate dramatically affected the final pH of the growth medium. A model was constructed using our data that predicts the effects of these acids, individually and in combination, on cell dry weight (CDW), PHA content (%CDW), PHA production, 3HV in the polymer, and final culture pH. Cell growth and PHA production improved approximately 1.5-fold over initial conditions when the proportion of butyrate was increased. Optimization of the phosphate buffer content in medium containing higher amounts of butyrate improved cell growth and PHA production more than 4-fold. The validated organic acid mixture analysis model can be used to optimize R. eutropha culture conditions, in order to meet targets for PHA production and/or polymer HV content. By modifying the growth medium made from treated industrial waste, such as palm oil mill effluent, more PHA can be produced.Malaysia. Ministry of Science, Technology and Innovation (MOSTI

Cardio-metabolic disease risk factors among south Asian labour migrants to the Middle East: A scoping review and policy analysis

This paper aims to explore the burgeoning burden of cardiovascular and metabolic disease (CMD) risk factors among South Asian labor migrants to the Middle East. We conducted a qualitative synthesis of literature using PubMed/Medline and grey literature searches, supplemented by a policy review of policies from the South Asian countries. We found a high burden of cardio-metabolic risk factors among the migrants as well as among the populations in the home and the host countries. For example, two studies reported the prevalence of diabetes mellitus (DM) ranging between 9 and 17% among South Asian migrants. Overweight and obesity were highly prevalent amongst South Asian male migrants; prevalence ranged from 30 to 66% (overweight) and 17-80% (obesity) respectively. The home country population had a significant CMD risk factor burden. Nearly 14 to 40% have three or more risk factors: such as hypertension (17 to 37%), diabetes (3 to 7%), overweight (18 to 41%), and obesity (2 to 15%). The host country also exhibited similar burden of risk factors: hypertension (13 to 38%), diabetes (8 to 17%), overweight (33 to 77%) and obesity (35 to 41%). Only Nepal, Bangladesh and Sri Lanka have some provisions related to screening of CMDs before labor migration. Further, analysis of policy papers showed that none of the reviewed documents had requirements for screening of any specific CMDs, but chronic diseases were used generically, failing to specify specific screening target. Given the high burden of risk factors, migrants\u27 health should become an urgent priority. The lack of specific focus on screening during different stages of labor migration should receive attention. The International Labour Organization and the International Office for Migration, through their country coordination teams should engage local stakeholders to create policies and plans to address this concern. Similarly, there is a need for the host country to become an equal partner in these efforts, as migrant\u27s better cardiometabolic health is in the benefit of both host and home countries