This review provides an overview of the progress in using low-gravity environment space to explore critical phenomena and test modern theoretical predictions. Gravity-induced variations hydrostatic pressure resulting density gradients adversely affect ground-based measurements near fluid points. Performing a can significantly reduce these difficulties. A number significant experiments have been performed low-Earth orbit. Experiments lambda transition liquid helium explored regime large...

We report experimental results for the depression of superfluid transition temperature ${\mathrm{T}}_{\ensuremath{\lambda}}$(Q) in $^{4}\mathrm{He}$ by a heat current Q. The data were obtained use thermometry with resolution 10 nK, and cover range 0.4\ensuremath{\lesssim}Q\ensuremath{\lesssim}10 \ensuremath{\mu}W/${\mathrm{cm}}^{2}$. They can be represented 1--${\mathit{T}}_{\ensuremath{\lambda}}$(Q)/${\mathit{T}}_{\ensuremath{\lambda}}$(0)=(Q/${\mathit{Q}}_{0}$${)}_{\mathit{x}}$...

We report measurements of the Seebeck coefficients boron carbides having compositions ${\mathrm{B}}_{12+x}{\mathrm{C}}_{3\ensuremath{-}x}$, $0.15<x<1.7$, from 6 to 900 K. These are large, $\ensuremath{\approx}200\ensuremath{\mu}\mathrm{V}/\mathrm{K}$ at 300 K, despite high carrier densities, $\ensuremath{\approx}{10}^{21}{\mathrm{cm}}^{\ensuremath{-}3}$. The also have unusual temperature dependencies and depend only weakly on density. exceptional properties can arise carbides' bipolaronic...

We report experimental results for the Kapitza resistance ${\mathit{R}}_{\mathit{K}}$ between gold and superfluid $^{4}\mathrm{He}$, which were obtained by using very-high-resolution thermometry. The data imply that is singular at transition temperature ${\mathit{T}}_{\ensuremath{\lambda}}$. Comparison with theory suggests singularity from a hydrodynamic effect proposed Landau, it associated vanishing of normal-fluid currents boundaries. Recently quantitative prediction part this has been...

We report experimental results for the thermal boundary resistance ${\mathrm{R}}_{\mathrm{K}}$ between gold and superfluid $^{4}\mathrm{He}$ which were obtaiend by use of thermometry with 3-nK resolution. The data imply that is singular at transition temperature ${\mathrm{T}}_{\ensuremath{\lambda}}$. Comparison theory suggests singularity from a hydrodynamic effect proposed Landau, it associated vanishing normal-fluid currents boundaries.

An electron beam may be used to generate bremsstrahlung photons that go on create photoneutrons within metals. This serves as a low-energy neutron source for irradiation experiments. In this article, we present simulation results optimizing photoneutron yield 10-MeV tantalum foil and erbium deuteride (ErD3). The thickness of the metal layers was varied. A 1.5 mm resulted in most reaching second layer. When layer ErD3 included, increased with secondary directly incident upon ErD3, did not...

We report on an experimental observation of self-organized criticality in ${}^{4}$He very close to its superfluid transition. A constant temperature gradient, independent the heat flux $Q$ through sample, is created along a vertical column by applying top column. This gradient equals gravity-induced transition temperature, indicating that thermal conductivity sample has self-organized. The closeness this state same throughout most and it depends only $Q$.

We report new high-resolution measurements of the thermal conductivity very near superfluid-transition temperature ${T}_{\ensuremath{\lambda}}$ on a thicker sample (0.57 cm) than had been used previously (0.22 by Lipa and Chui (LC). Our results deviate less from expected for bulk do LC data. data, LC, previous 0.0025-cm-thick are consistent with simple phenomenological model effect solid boundaries upon $\ensuremath{\lambda}$.

The behavior of the superfluid -- normal fluid interface in ${}^{4}\mathrm{He}$ has been studied presence a heat flux, $\stackrel{\ensuremath{\rightarrow}}{Q}$, range $0.1<Q<6\phantom{\rule{0ex}{0ex}}\mathrm{erg}{\mathrm{s}}^{\ensuremath{-}1}{\mathrm{cm}}^{\ensuremath{-}2}$. Fourier's Law, $\stackrel{\ensuremath{\rightarrow}}{Q}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\ensuremath{-}\ensuremath{\kappa}▽T$, observed, for first time, to break down very close interface. In nonlinear...

Palladium nanoparticles with two different ligands were used as electrocatalysts at low temperature in a hermetic one-pot electrochemical cell either LiOH or LiOD electrolyte. During initial low-pressure experiments involving Pd nanoparticle epigallocatechin gallate (EGCG) ligands, an abrupt, significant pressure drop occurred the headspace air from 1.59 to 0.055 bar. This astounding, repeatable, and unexplained result initiated further experimentation. Synthetic methods for bifunctional...

A new generation of digital multimeters was used to compare the ratios resistances wire-wound reference resistors and quantized Hall resistances.The accuracies are better than 0.1 ppm for as large 4: 1 if a~ calibrated with a Josephson array.

A charged capacitor which is placed with a semiconductor in closed loop will normally discharge characteristic time \ensuremath{\tau}=1/RC. We show, however, that if of high purity subjected to rf bias frequency \ensuremath{\omega}, does not occur the voltage across proportional an integer multiple \ensuremath{\Elzxh}\ensuremath{\omega}/e. Thus may be converted dc voltage. The ac conversion made possible by interplay between Bloch oscillations induced electric field external source and those...

In this paper we discuss the advantages and challenges of utilizing Fission Fragment Rocket Engines (FFREs) to dramatically reduce transit time in space travel, for example, traveling Mars. We methods decrease size weight FFREs. These include metallic deuterides as moderators, driving engines with electron beam bremsstrahlung, operating FFREs subcritical assemblies, not nuclear reactors. these other new innovations based upon improved materials technology that may be integrated into a...

We report experimental results for the thermal boundary resistance R K between gold and superfluid 4 He which were obtained by using thermometry with three-nanokelvin resolution. The data imply that is singular at transition temperature T λ . For t≡1-T/T \lesssim10 -4 , becomes noticeably dependent on heat flux Q used to make measurement. reduced t c this nonlinear first observed approximately proportional Q. t≤t dR /dQ 1/t.

This article details the design, modeling, construction, and evaluation of an open system calorimeter that operates in a normal room environment to measure endothermic or exothermic events subjected steady heat flux. The is unique because it allows measurement energy power from “open” system, where flux enters leaves calorimetric boundary well-controlled manner. It also novel utilizes solid state heating cooling assembly acts as electronic reservoir. capable measuring levels few milliwatts...

Regional universities are expanding rapidly in their research impact today. More generally, these emerging significance and ability to produce rapid positive social change. Many national laboratories have developed opportunities shared governance through major university collaborations, with an emphasis on nearby educational institutions. This is state-of-the-art facilities less populated regions of the United States that were under-capitalized infrastructure past. regional today both...