Alpha radiolytic degradation of <Emphasis Type="Italic">N,N</Emphasis>-dihexyl octanamide

The primary purpose of this study was to understand the alpha radiolytic degradation behavior of N,N-dihexyl octanamide (DHOA) vis a vis tributyl phosphate (TBP) solutions in n-dodecane under plutonium loading conditions. These studies were carried out as a function of dose on different Pu loaded samples (containing 0.002-10 g/L Pu) from 4 M HNO₃ medium. These Pu loaded solutions were evaluated for stripping behavior by contacting with 0.5 M NH₂OH at 0.5 M HNO₃ solutions. Organic phase analysis was carried out by gas chromatography (GC) and by visible spectrophotometry. These studies clearly indicated that Pu stripping becomes difficult with increased dose in the case of TBP system. On the other hand, no such problem was observed in DHOA system during stripping of plutonium, thereby indicating that DHOA is a promising candidate for the reprocessing of high burn up Pu rich spent fuels.     

Influence of the small substitution of Z=Ni, Cu, Cr, V for Fe on the magnetic, magnetocaloric, and magnetoelastic properties of LaFe11.4Si1.6

We have studied the magnetic, magnetocaloric, and magnetostriction properties of LaFe_11.4Si_1.6 and La(Fe_0.99Z_0.01)_11.4Si_1.6 (Z=Ni, Cu, Cr, V) compounds using magnetization and strain gauge techniques. It was found that substitution of 1% of the Fe by Z-elements results in an increase in the Curie temperature (T_C), and affects the magnetostriction and magnetocaloric properties of the parent compound, LaFe_11.4Si_1.6. A maximum shift in T_C of about 11 K, and significantly smaller hysteresis losses in the vicinity of T_C compared with those of the base compound, were found for Z=V. The maximum magnetovolume coupling constant was estimated to be n_dd≈2.7×10⁻³ (μ_B/Fe atom)⁻² for the parent compound. The changes in the volume magnetostriction, the magnetovolume coupling constant, and the magnetocaloric properties are strongly correlated with composition. The relative effects of the variation in cell parameters and electron concentration on the magnetostriction, T_C, and the magnetocaloric properties are discussed.     

Dynamics of uniform quantum gases, I: Density and current correlations

A unified approach valid for any wavenumber q, frequency ω, and temperature T is presented for uniform ideal quantum gases allowing for a comprehensive study of number density and particle-current density response functions. Exact analytical expressions are obtained for spectral functions in terms of polylogarithms. Also, particle-number and particle-current static susceptibilities are presented which, for fugacity less than unity, additionally involve Kummer functions. The q- and T-dependent transverse-current static susceptibility is used to show explicitly that current correlations are of long range in a Bose-condensed uniform ideal gas but for bosons at T>T_c and for Fermi and Boltzmann gases at all temperatures these correlations are of short range. Contact repulsive interactions for systems of neutral quantum particles are considered within the random phase approximation. The expressions for particle-number and transverse-current susceptibilities are utilized to discuss the existence or nonexistence of superfluidity in the systems under consideration.     

Heteroatom-Doped Metal-Free Carbon Nanomaterials as Potential Electrocatalysts

In recent years, heteroatom-incorporated specially structured metal-free carbon nanomaterials have drawn huge attention among researchers. In comparison to the undoped carbon nanomaterials, heteroatoms such as nitrogen-, sulphur-, boron-, phosphorous-, etc., incorporated nanomaterials have become well-accepted as potential electrocatalysts in water splitting, supercapacitors and dye-sensitized solar cells. This review puts special emphasis on the most popular synthetic strategies of heteroatom-doped and co-doped metal-free carbon nanomaterials, viz., chemical vapor deposition, pyrolysis, solvothermal process, etc., utilized in last two decades. These specially structured nanomaterials’ extensive applications as potential electrocatalysts are taken into consideration in this article. Their comparative enhancement of electrocatalytic performance with incorporation of heteroatoms has also been discussed.     

N-Heterocyclic Olefins on a Silicon Surface

The adsorption of N-heterocyclic olefins (NHOs) on silicon is investigated in a combined scanning tunneling microscopy, X-ray photoelectron spectroscopy, and density functional theory study. We find that both of the studied NHOs bind covalently, with ylidic character, to the silicon adatoms of the substrate and exhibit good thermal stability. The adsorption geometry strongly depends on the N-substituents: for large N-substituents, an upright adsorption geometry is favored, while a flat-lying geometry is found for the NHO with smaller wingtips. These different geometries strongly influence the quality and properties of the obtained monolayers. The upright geometry leads to the formation of ordered monolayers, whereas the flat-lying NHOs yield a mostly disordered, but denser, monolayer. The obtained monolayers both show large work function reductions, as the higher density of the flat-lying monolayer is found to compensate for the smaller vertical dipole moments. Our findings offer new prospects in the design of tailor-made ligand structures in organic electronics and optoelectronics, catalysis, and material science.