Use of CR-39 films for nuclear radiation shielding efficacy evaluation of lining materials for combat vehicles

All materials provide, to a lesser or greater extent, shielding against nuclear radiations. Armoured fighting vehicles (AFVs) have steel as the structural material, which appears to be a reasonably good gamma and neutron shield material but a shield of pure iron would not be equally effective against whole range of neutron energies as it has a few resonances in electron volt range, and it reduces energy of fast neutrons to lower energy neutrons. These neutrons will be absorbed through radiative capture and emit gamma radiations. Thus it is essential that an effective shield should contain a large amount of moderating material, hydrogen being preferred with low atomic number materials (B, C, Li) and lead (Pb) to ensure that the neutrons do not diffuse at intermediate energies in the shield as well as gamma attenuation will also take place. In order to have a suitable shield material for armoured vehicles which serves as neutron and gamma radiation attenuator, polyethylene polymer with fillers lining materials are preferred. These materials were evaluated against gamma and fast neutrons using radioactive sources for suitability to fitment into combat vehicle as per the requirement of protection factor values. The detector for gamma radiation was used as Nal(Tl) while for neutron, CR-39 film was used.Use of CR-39 films for nuclear radiation shielding efficacy evaluation of lining materials for combat vehicles Deepak Gopalani1*, A S Jodha1, M K Das1, R K Singh2 and G L Baheti1 1Defence Laboratory, Jodhpur-342 011, Rajasthan, India 2Defence Material & Store Research & Developement Establishment, Kanpur-208 013, Uttar Pradesh, India E-mail : [email protected] Laboratory, Jodhpur-342 011, Rajasthan, India 2Defence Material & Store Research & Developement Establishment, Kanpur-208 013, Uttar Pradesh, Indi

Effect of Thermoelectric Cooling in Nanoscale Junctions

We propose a thermoelectric cooling device based on an atomic-sized junction. Using first-principles approaches, we investigate the working conditions and the coefficient of performance (COP) of an atomic-scale electronic refrigerator where the effects of phonon's thermal current and local heating are included. It is observed that the functioning of the thermoelectric nano-refrigerator is restricted to a narrow range of driving voltages. Compared with the bulk thermoelectric system with the overwhelmingly irreversible Joule heating, the 4-Al atomic refrigerator has a higher efficiency than a bulk thermoelectric refrigerator with the same $ZT$ due to suppressed local heating via the quasi-ballistic electron transport and small driving voltages. Quantum nature due to the size minimization offered by atomic-level control of properties facilitates electron cooling beyond the expectation of the conventional thermoelectric device theory.Comment: 8 figure

Molecular design and control of fullerene-based bi-thermoelectric materials

Molecular junctions are a versatile test bed for investigating nanoscale thermoelectricity and contribute to the design of new cost-effective environmentally friendly organic thermoelectric materials. It was suggested that transport resonances associated with discrete molecular levels could play a key role in thermoelectric performance, but no direct experimental evidence has been reported. Here we study single-molecule junctions of the endohedral fullerene Sc3N@C8 connected to gold electrodes using a scanning tunnelling microscope. We find that the magnitude and sign of the thermopower depend strongly on the orientation of the molecule and on applied pressure. Our calculations show that Sc3N inside the fullerene cage creates a sharp resonance near the Fermi level, whose energetic location, and hence the thermopower, can be tuned by applying pressure. These results reveal that Sc3N@C80 is a bi-thermoelectric material, exhibiting both positive and negative thermopower, and provide an unambiguous demonstration of the importance of transport resonances in molecular junctions

REVEL: An Ensemble Method for Predicting the Pathogenicity of Rare Missense Variants

Supplemental Data Supplemental Data include one figure and five tables and can be found with this article online at http://dx.doi.org/10.1016/j.ajhg.2016.08.016. Supplemental Data Document S1. Figure S1 and Tables S1–S5 Download Document S2. Article plus Supplemental Data Download Web Resources ClinVar, https://www.ncbi.nlm.nih.gov/clinvar/ dbNSFP, https://sites.google.com/site/jpopgen/dbNSFP Human Gene Mutation Database, http://www.hgmd.cf.ac.uk/ REVEL, https://sites.google.com/site/revelgenomics/ SwissVar, http://swissvar.expasy.org/ The vast majority of coding variants are rare, and assessment of the contribution of rare variants to complex traits is hampered by low statistical power and limited functional data. Improved methods for predicting the pathogenicity of rare coding variants are needed to facilitate the discovery of disease variants from exome sequencing studies. We developed REVEL (rare exome variant ensemble learner), an ensemble method for predicting the pathogenicity of missense variants on the basis of individual tools: MutPred, FATHMM, VEST, PolyPhen, SIFT, PROVEAN, MutationAssessor, MutationTaster, LRT, GERP, SiPhy, phyloP, and phastCons. REVEL was trained with recently discovered pathogenic and rare neutral missense variants, excluding those previously used to train its constituent tools. When applied to two independent test sets, REVEL had the best overall performance (p < 10−12) as compared to any individual tool and seven ensemble methods: MetaSVM, MetaLR, KGGSeq, Condel, CADD, DANN, and Eigen. Importantly, REVEL also had the best performance for distinguishing pathogenic from rare neutral variants with allele frequencies <0.5%. The area under the receiver operating characteristic curve (AUC) for REVEL was 0.046–0.182 higher in an independent test set of 935 recent SwissVar disease variants and 123,935 putatively neutral exome sequencing variants and 0.027–0.143 higher in an independent test set of 1,953 pathogenic and 2,406 benign variants recently reported in ClinVar than the AUCs for other ensemble methods. We provide pre-computed REVEL scores for all possible human missense variants to facilitate the identification of pathogenic variants in the sea of rare variants discovered as sequencing studies expand in scale

Reactions of 2-mercaptobenzoic acid with divalent alkaline earth metal ions: Synthesis, spectral studies, and single-crystal X-ray structures of calcium, strontium, and barium complexes of 2,2 '-dithiobis(benzoic acid)

The treatment of MCl2. nH(2)O (M = Ca, Sr, or Ba) with 2-mercaptobenzoic acid (H-2-MBA) in a 1:2 ratio in an EtOH/H2O/NH3 mixture leads to the formation of extended polymeric solids [{Ca(OOCC6H4SSC6H4COO)(H2O)(2)}.0.5(C2H5OH)](n) (1), [{Sr(OOCC6H4SSC6H4COO)(H2O)(2)}.0.5(C2H5OH)](n) (2), and [{Ba-2(OOCC6H4SSC6H4COO)(2)- (H2O)(2)}.0.5H(2)O](n) (3), respectively. In all of the cases, under the reaction conditions employed, the H-2-MBA ligand undergoes thiol oxidation to form 2,2'-dithiobis(benzoic acid) (H-2-DTBB). While the DTBB forms a 1:1 complex with heavier alkaline earth metals (1-3), only an ammonium salt, [(HOOCC6H4SSC6H4COOH)-(HOOCC6H4SSC6H4COONH4)] (4), was obtained as the final product in the reaction of H-2-MBA with MgCl2. 6H(2)O. Compounds 1-4 have been characterized with the aid of elemental analysis, thermal analysis, and infrared spectroscopic studies. All of the products are found to be thermally stable and do not melt on heating to 250 degreesC. Thermogravimetry on complexes 1-3 indicates the loss of coordinated and lattice water/solvent molecules below 200 degreesC (for complex 2) or 350 degreesC (for complexes 1 and 3). The solid-state structures of all of the derivatives 1-4 have been established by single-crystal X-ray diffraction studies, The calcium and strontium coordination polymers 1 and 2 are isomorphous. The DTBB ligands in 1 and 2 are hexadentate, and the compounds have a channel structure in which solvent ethanol molecules are included. In compound 3, barium ion forms a complex 3-dimensional coordination polymer where both the carboxylate and the sulfur centers of die DTBB ligands (which are hepta- and octadentate) coordinate to the metal

Metal containing new inorganic ring systems based on siloxane and phosphazane frameworks

High-Field P-31 NMR spectroscopy and single crystal X-ray diffraction studies have been used to study the ring opening and nucleophilic substitution reactions of the lambda (3)-cyclotriphosphazane [EtNPCl](3). The synthesis of the ring opened silicophosphonate [RSi(OH){OP(O)(H)(OH)}](2)O (R=(2,6-iPr(2)C(6)H(3))NSiMe3) (1) represents the first ever molecular silicophosphonate to be isolated bearing free reactive hydroxyl groups. The structure and conformation of the bulky aryloxide substituted lambda (3)-cyclotriphosphazane derivative [EtNP(OAr)](3) (Ar = 2,6-iPr(2)C(6)H(3)) (2) has also been investigated. Interaction of 2 with transition metal precursor complexes leads to the isolation of phosphazane metal complexes with different mode of co-ordination of 2. Further, the reaction of Cp*Ti(OAr)Cl-2 (Ar = 2,6-(CH3)(2)C6H3H) with O{SiPh2(OH)}(2) gave the eight-membered trititanosiloxane [Cp*Ti(Cl) (O(SiPh2O)(2)SiPh2O) (3). Siloxane chain expansion effects, presumed to be a consequence of ring strain, have been observed in the product. The presence of reactive Ti-Cl bond in 3 offers opportunities for its reaction chemistry to be explored

Novel synthesis and ring closure reactions of 3-hydrazino-1,2,4-triazolo[3,4-<i style="">b</i>]benzothiazole

625-6273-Hydrazino-1,2,4-triazolo[3,4-b]benzothiazole 2 is prepared by heating 3-chloro-1,2,4-triazino[3,4-b]benzothiazole-4(H)-one 1 with hydrazine hydrate. This transformation takes place with decarbonylation resulting in ring contraction and simultaneous replacement of chlorine by hydrazino group. Compound 2 on heating independently with urea and carbon disulphide in the presence of alkali gave 3'-hydroxy 3 and 3'-mercapto-1,2,4-triazolo[4',5':1,5]-1,2,4-triazolo[3,4-b] benzothiazole 4 respect­ively. Treatment of cold solution of 2 in phosphoric acid with sodium nitrite solution affords 1,2,3,4-tetra­zolo[1',5':1,5]-1,2, 4-triazolo[3,4-b]benzothiazole 5. 3'-Aryl-1, 2, 4-triazolo[4',5':1,5]-1, 2, 4-triazolo[3,4-b] benzothiazoles 7a-e have been also prepared by the reaction of 2 with aryl aldehydes in the presence of acetic acid