First-principles study of metal-semiconductor contact between MX2 (M = Nb,Pt; X = S,Se) monolayers

First principles calculations are performed to investigate the structural and electronic properties of MX₂ (M = Nb, Pt; X = S, Se) monolayers and their van der Waals (vdW) heterostructures. The dynamical stability of monolayers and vdW heterostructures is confirmed by binding energy and phonon spectra. An indirect band gap nature is found for PtS₂ and PtSe₂ monolayers while NbS₂, NbSe₂ and all vdW heterostructures are metals. The intrinsic electronic properties of both NbX₂ and PtX₂ are well preserved due to weak vdW contact. It is demonstrated that a p-type Schottky contact with a small barrier height is formed at NbX₂-PtX₂ interface. The zero tunnel barrier and higher potential drop across the interface in these contacts imply large transfer of charge carriers across the interface, making them potential candidates in nanoelectronic device applications.     

Characteristics and behavior of a99Mo/99mTc generator using irradiated titanium molybdate as column matrix

A⁹⁹Mo/^99mTc generator, system was made with a performed titanium molybdate gel. The irradiation was carried out at a medium neutron flux of 1.5×10¹³ n cm^–2·s^–1. The irradiated matrix was loaded on top of a column composed of hydrous zirconium oxide alumina. The elution efficiency and the amount of total technetium per mCi^99mTc in the generator eluents have been determined. Molybdenum breakthrough has also been determined and compared with literature values. The influence of the particle size, water content, neutron flux and molybdenum content on the total^99mTc-activity has been investigated.     

Deposition of Diamond-like Carbon Films using Graphite Sputtering in Neon Dense Plasma

This paper reports the deposition of diamond-like carbon (DLC) films on Si <100>, using a low energy (1.45 kJ) dense plasma focus assisted sputtering of graphite insert at the tip of the tapered anode. The substrates are placed in front of the anode at different axial and angular positions and are exposed to multiple focus shots. The information regarding the DLC structure is acquired by using Raman spectroscopy. The spectra are characterized by two broad bands known as “G-band” and “D-band”. The results point towards the formation of DLC films with both sp³ (diamond like) and sp² (graphite like) domains. In X-ray diffraction (XRD) pattern, no additional peak is observed except a peak at 2θ = 69° which corresponds to the silicon (Si) substrate. The intensity of Si peak is reduced after treatment indicating the deposition of amorphous carbon. Scanning electron microscopy (SEM) results demonstrate that the smoothness of the film increases with increasing the substrate angular positions with respect to the anode axis. Energy dispersive X-ray (EDX) analysis reveals that the films deposited at lower axial and angular positions are thicker which is complemented by the cross-sectional views of the films.     

Comparative evaluation of four different99mTc-sulfur colloid kits used for liver scanning

The distribution of four different commercially available A, B, C, D kits (^99mTc-sulfur colloid) for hepatoimaging was compared in mice by organ radioassay and in rabbits for blood clearance. The distribution of kits A and C (single step kits) was assessed in the human by blood clearance, external liver, spleen measurement, and scintillation camera imaging. Kit A reaches a high concentration in liver within 15–20 minutes with relatively high surrounding tissue background, and superior spleen scintiphotos. However, when kit C was used, a high activity concentration in the liver was reached within 10–15 minutes with low tissue background and faint visualization of the radiotracer in the spleen. Blood clearance of the four^99mTc-sulfur colloids was determined in rabbits. The data obtained indicated that the four hepatoagents exhibit rapid blood clearance but the initial decrease of blood activity curve of kit D was relatively faster than the other three hepatic agents. The biodistribution is similar for the four^99mTc-S-colloids but the blood retained higher activity residue using kit A compared with others. The formation of^99mTc-sulfur colloid using kits B, D (multistep kits) involves many steps after the addition of^99mTcO ₄ ^– to the reagent. These procedures are time consuming, required facilities at the medical institutions and give rise to the radiation exposure. While single step kits A and C have the same diagnostic value, the use of kit C allows a reduction of absorbed radiation, which may be useful in the liver exploration in children.     

New lipoxygenase and cholinesterase inhibitory sphingolipids from Carthamus oxyacantha

Two new sphingolipids: oxyacanthin A [(2S,3S,4R)-2-{[(2R,5E)-2-hydroxyoctadec-5-enoyl]amino}hexaeicosane-1,3,4-triol; 1] and B [(2S,3S,4R)-2-{[(2R,5E)-2-hydroxyoctadec-5-enoyl]amino}hexaeicosane-1,3,4-triol-1-O-β-D-glucopyranoside; 2], together with 1-octacosanol, β-sitosterol, β-sitosterol 3-O-β-D-glucopyranoside and luteolin 7-O-β-glucopyranoside were isolated from the methanolic extract of the whole plant of Carthamus oxyacantha. Their structures were elucidated using ¹H and ¹³C NMR spectra and 2D NMR analyses (HMQC, HMBC and COSY) in combination with mass spectrometry (EI-MS, HR-EI-MS, FAB-MS and HR-FAB-MS) experiments and in comparison with the literature data of the related compounds. Both the compounds 1 and 2 showed inhibitory potential against lipoxygenase (LOX) in a concentration-dependent manner with IC₅₀ values 83.3 ± 1.3 and 245.7 ± 1.1 µM, whereas compound 2 showed inhibition against enzymes acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) with IC₅₀ values 65.3 ± 0.1 and 93.6 ± 0.1 µM, respectively.     

Mixed convection flow of hybrid nanoparticle along a Riga surface with Thomson and Troian slip condition

Journal of Thermal Analysis and Calorimetry - The target of current research is to discuss the induced magnetic field stagnation point flow of carbon nanoliquids influenced by Riga surface with...