Thermodynamics of a Higher Order Phase Transition: Scaling Exponents and Scaling Laws

The well known scaling laws relating critical exponents in a second order phase transition have been generalized to the case of an arbitrarily higher order phase transition. In a higher order transition, such as one suggested for the superconducting transition in Ba$_{0.6}$K$_{0.4}$BiO$_3$ and in Bi$_2$Sr$_2$CaCu$_2$O$_8$, there are singularities in higher order derivatives of the free energy. A relation between exponents of different observables has been found, regardless of whether the exponents are classical (mean-field theory, no fluctuations, integer order of a transition) or not (fluctuation effects included). We also comment on the phase transition in a thin film.Comment: 10 pages, no figure

Studies on the toxicity of Vacor (RH-787) on the reproductive biology of Rattus rattus rufescens

Vacor (RH-787), a relatively new rodenticide, was evaluated for the control of Rattus rattus rufescens. The symptoms of paralysis in hind limbs were observed after feeding it to rodents. The susceptibility to this rodenticide in Rattus rattus increased with the increase in its concentration. Experimental observations revealed that RH-787 bait with 0.0125% concentration affects the reproductive biology of the rats. Bait with 0.025% Vacor proved sublethal and within 5 days 70% mortality was observed, while 100% mortality was observed when rats were fed with 0.05% Vaco

High efficiency compound semiconductor concentrator photovoltaics

Special emphasis was given to the high yield pilot production of packaged AlGaAs/GaAs concentrator solar cells, using organometallic VPE for materials growth, the demonstration of a concentrator module using 12 of these cells which achieved 16.4 percent conversion efficiency at 50 C coolant inlet temperature, and the demonstration of a spectral splitting converter module that achieved in excess of 20 percent efficiency. This converter employed ten silicon and ten AlGaAs cells with a dichroic filter functioning as the beam splitter. A monolithic array of AlGaAs/GaAs solar cells is described

OM-VPE grown materials for high efficiency solar cells

Organometallic sources are available for all the III-V elements and a variety of dopants; thus it is possible to use the technique to grow a wide variety of semiconductor compounds. AlGaAsSb and AlGaInAs alloys for multijunction monolithic solar cells were grown by OM-VPE. While the effort concentrated on terrestrial applications, the success of OM-VPE grown GaAs/AlGaAs concentrator solar cells (23% at 400 suns) demonstrates that OM-VPE is suitable for growing high efficiency solar cells in large quantities for space applications. In addition, OM-VPE offers the potential for substantial cost reduction of photovoltaic devices with scale up and automation and due to high process yield from reproducible, uniform epitaxial growths with excellent surface morphology

Analytical approach to the transition to thermal hopping in the thin- and thick-wall approximations

The nature of the transition from the quantum tunneling regime at low temperatures to the thermal hopping regime at high temperatures is investigated analytically in scalar field theory. An analytical bounce solution is presented, which reproduces the action in the thin-wall as well as thick-wall limits. The transition is first order for the case of a thin wall while for the thick wall case it is second order.Comment: Latex file, 22 pages, 4 Postscript figure

A global study of α\alpha-clusters decay in heavy and superheavy nuclei with half-life and preformation factor

A detailed study of $\alpha$-clusters decay is exhibited by incorporating crucial microscopic nuclear structure information into the estimations of half-life and preformation factor. For the first time, using the k-cross validation approach, two semi-empirical formulas for (i) $\alpha$-decay half-life and (ii) $\alpha$-particle preformation factor, are picked out and subsequently modified by including shell, odd-nucleon blocking, and asymmetry effects along with the usual dependence on $\alpha$-decay energy ($Q_{\alpha}$) and angular momentum of $\alpha$-particle. Both the formulas are fitted for the two different regions separated by neutron number N$=$126, as from the experimental systematics the role of N$=$126 shell closure is found decisive in determining the trends of $Q_{\alpha}$, $\alpha$-decay half-life, and $\alpha$-particle preformation factor. It is found that the inclusion of the above-mentioned degrees of freedom significantly reduces the errors in the estimations when compared with several other similar modified/refitted semi-empirical relations indicating the robustness of the proposed formulas. The predictions of $\alpha$-decay half-life throughout the periodic chart have been made including the unknown territory, future probable decay chain of self-conjugate nucleus $^{112}$Ba terminated on $^{100}$Sn, decay chain of $^{208}$Pa through new isotope $^{204}$Ac as well as decay chains of awaiting superheavy nuclei $^{298}$Og and $^{299}$120.Comment: 13 pages, 7 Figures, Accepted in European Physical Journal A (2024