Hexanitrohexaazaisowurtzitane or CL-20 in India: Synthesis and Characterisation

Hexanitrohexaazaisowurtzitane (HNIW) more commonly called CL-20, the highest density and the most powerful real world explosive, has been made with very high yield and a high product purity. CL-20 is thoroughly characterised by spectral data (IR, NMR and mass) along with electron spectroscopy for chemical analysis (ESCA) and X-ray diffractogram. Furthermore, small-scale sensitivity tests have also been carried out

RNA interference in Lepidoptera: an overview of successful and unsuccessful studies and implications for experimental design

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Nitrogen doping into titanium dioxide by the sol–gel method using nitric acid

N-doped TiO(2) has been prepared by use of sol-gel systems containing titanium alkoxide, with nitric acid as the nitrogen source. The time needed for gelation of the systems was drastically reduced by ultrasonic irradiation. The peaks assigned to the nitrate and nitrous ions were observed by FT-IR measurement during the sol-gel reaction. The N-doping was confirmed by the observation of N-O peaks in the XPS spectrum of the sample heated at 400 A degrees C. The nitrate ion acted as an oxidizer of the ethanol solvent and titanium species. The TiO(2) became doped with nitrogen oxide species as a result of reduction of nitrate ion incorporated into the dried gel samples. These results indicated that the added nitric acid was reduced during the sol-gel transition and heating process, and the resulting NO species were situated in the titania networks. The UV and visible photocatalytic activity of the samples was confirmed by the degradation of trichloroethylene.ArticleRESEARCH ON CHEMICAL INTERMEDIATES. 37(8):869-881 (2011)journal articl

Genetic variability in the precore and core promoter regions of hepatitis B virus strains in Karachi

BACKGROUND: Hepatitis B virus (HBV) genotypes have distinct geographic distribution. Moreover, much genetic variability has been described in the precore (PC) and basal core promoter (BCP) regions of the HBV genome. The local prevalence of HBV genotypes and mutations has not been well studied. The aim of the present study is to determine the prevalence of HBV genotypes and mutations in the PC and BCP region in HBV strains in Karachi. METHODS: A total of 109 chronic hepatitis B patients with detectable HBV DNA by a PCR assay were enrolled in the study. Sera were tested for HBeAg, anti-HBe antibody and liver profile. HBV genotypes and mutations in the PC and BCP regions were detected by INNO-LiPA line-probe assays. RESULTS: Of the 109 patients investigated, 38 (35%) were HBeAg positive while 71 (65%) were HBeAg negative. Genotype D was present in 100% of the patients. Two patients had co-infection with genotype A. There was no significant difference in the baseline characteristics, mean ALT levels, and presence of clinical cirrhosis in patients with HBeAg positive or negative strains with or without PC and BCP mutations. Of the 38 HBeAg positive patients, 9 (24%) had PC and BCP mutations. In the HBeAg negative patient group, mutations were detected in 44 (62%) of the strains investigated. More than one mutation was common, seen in 26 (37%) patients with HBeAg negative disease and 6 (16%) patients with HBeAg positive disease. Twelve (17%) HBeAg negative patients had dual T1762 and A1764 mutations. None of the HBeAg positive patients had T1762 mutation. Mutations were undetectable in 27 (38%) of patients with HBeAg negative disease. CONCLUSION: Our study shows that type D is the main HBV genotype in Karachi, Pakistan. Significant numbers of patients infected with this genotype have PC and BCP variants. Mutations at more than one site are common. Patients harboring these mutants do not differ significantly in their clinical presentation from patients having wild type infection

Palladium Nanoparticles Loaded on Carbon Modified TiO2 Nanobelts for Enhanced Methanol Electrooxidation

Made available based on the terms of the Springer open license. Publication available at Springer via http://dx.doi.org/10.5101/nml.v5i3.p202-212Carbon modified TiO2 nanobelts (TiO2-C) were synthesized using a hydrothermal growth method, as a support material for palladium (Pd) nanoparticles (Pd/TiO2-C) to improve the electrocatalytic performance for methanol electrooxidation by comparison to Pd nanoparticles on bare TiO2 nanobelts (Pd/TiO2) and activated carbon (Pd/AC). Cyclic voltammetry characterization was conducted with respect to saturated calomel electrode (SCE) in an alkaline methanol solution, and the results indicate that the specific activity of Pd/TiO2-C is 2.2 times that of Pd/AC and 1.5 times that of Pd/TiO2. Chronoamperometry results revealed that the TiO2-C support was comparable in stability to activated carbon; but possesses an enhanced current density for methanol oxidation at a potential of -0.2 V vs. SCE. The current study demonstrates the potential of Pd nanoparticle loaded on hierarchical TiO2-C nanobelts for electrocatalytic applications such as fuel cells and batteries.FedDev Ontario through the Applied Research and Commercialization (ARC) InitiativeNatural Sciences and Engineering Research Council of Canada (NSERC) programMicrobonds, Inc

Advances in High Energy Materials (Review Paper)

Research and development efforts for realizing higher performance levels of high energy materials (HEMs) are continued unabated all over the globe. Of late, it is becoming increasingly necessary to ensure that such materials are also eco-friendly. This has provided thrust to research in the area of force multiplying HEMs and compounds free from pollution causing components. Enhancement of the performance necessitates introduction of strained structure or increase in oxygen balance to achieve near stoichiometry. The search for environment friendly molecules is focused on chlorine free propellant compositions and lead free primary explosives. Energetic polymers offer added advantage of partitioning of energy and thus not necessitating the concentration of only solid components (HEMs and metal fuels) in the formulations, to achieve higher performance, thereby leading to improvement in energetics without adversely affecting the processability and mechanical properties. During recent times, research in the area of insensitive explosives has received impetus particularly with the signature of STANAG. This paper gives a review of the all-round advances in the areas of HEMs encompassing oxidizers, high-energy dense materials, insensitive high-energy materials, polymers and plasticizers. Selected formulations based on these materials are also included.Defence Science Journal, 2010, 60(2), pp.137-151, DOI:http://dx.doi.org/10.14429/dsj.60.32

Parametric amplification and wavelength conversion of single-and dual-polarization DQPSK signals

We demonstrate system experiments for polarization-independent parametric amplification and wavelength conversion of single-channel differential quadrature phase-shift keying (DQPSK) signals up to 112 Gbit/s. Dual-pump four-wave mixing in a highly nonlinear fiber is utilized to achieve up to 20dB ON-OFF gain and conversion efficiency. The investigations are done in a polarization-dependent (straight) as well as in a polarization-independent (loop) configuration using single-and dual-polarization DQPSK. Particular attention is paid to the resulting optical signal-to-noise ratio penalties after the amplification. We ascribe this to pump-induced nonlinear phase noise. It is shown that this type of excess noise is increased for the loop configuration in comparison with the straight configuration due to Rayleigh backscattering and that it depends on the input polarization of the signal. Still, the penalty can be made negligible using high-quality pump sources

Synthesis of CL-20: By oxidative debenzylation with cerium (IV) ammonium nitrate (CAN)

505-508Hexanitrohexaazaisowurtzitane (HNIW or CL-20), one of the most powerful high explosives of today, is a polycyclic nitramine cage compound. The synthesis of CL-20 is described from 2,6,8,12-tetraacetyl-4,10-dibenzyl hexaazaisowurtzitane (TADBIW) using debenzylation followed by nitration. TADBIW on reaction with cerium (IV) ammonium nitrate (CAN) gives the debenzylated product, which on nitration with HNO₃/H₂SO₄ provides CL-20. Alternatively, the debenzylated product on acetylation yields 2,4,6,8,10,12-hexaacetyl-2,4,6,8,10,12-hexaazaisowurtzitane (HAIW), which on nitration produces CL-20