Low Temperature Vulcanisation Technique for CR BIIR Blend for Encapsulation of Oceanic Sensors

Blend of chloroprene rubber (CR) and bromobutyl rubber (BIIR) is used for encapsulation of piezo sensors used in sea water. Conventional encapsulation method of these sensors involving high temperature vulcanisation (HTV) often leads to deterioration of piezo properties due to thermal degradation. This paper reports a low temperature vulcanisation (LTV) technique carried out at 90 °C for CR-BIIR blend using chlorinated polyethylene (CPE) as compatibiliser and LTV system consisting of modified di-o-tolyl guanidine and thiocarbanilide as accelerators and ZnO as curing agent. The conventionally used scavenger MgO was eliminated and only ZnO was used to boost the cure reaction. Properties specific to sonar sensors, namely, acoustic transparency, electrical resistivity, water absorption and physico‑mechanical properties were evaluated besides evaluation of morphology. The results are found to compare better than the conventional blend. Accelerated thermal ageing at 70 °C for 7 days yielded 97 % retention of tensile strength. The technique was implemented in a PZT hydrophone sensor and was successfully underwater tested

Synthesis and Characterisation of Poly (aminotrinitrophenylene)

Poly(amipotrinitrophenylene) (PATNP), a thermally-stable explosive has been synthesisied by ring amination of polynitropolyphenylene (PNP) using hydroxylamine hydrochloride in dimethyl formamide in the presence of alcoholic KOH. The compound has been characterised by infrared and differential thermal analysis (DTA), which showed an exothermic peak in the range 450-560 °C. Impact and friction sensitivities of PATNP were found to be less than those of PNP. Calorimetric value of the new compound was 3284 J/g

Detecting mycobacteraemia for diagnosing tuberculosis

Background & objectives: In human immunodeficiency virus (HIV) infected persons with pulmonary tuberculosis (TB), sputum may not always show acid fast bacilli (AFB). Moreover, in most cases of suspected extrapulmonary TB (irrespective of HIV status) mycobacteria-containing material is not readily available for investigation. This study evaluated whether blood culture for Mycobacterium tuberculosis bacteraemia (mycobacteraemia) help in diagnosing TB in such cases. Methods: A total of 93 consecutive subjects with a clinical diagnosis of tuberculosis with or without laboratory confirmation, 42 with and 38 without coexisting HIV infection, and 13 patients with HIV infection without clinical evidence of TB were enrolled. Mycobacterial blood cultures were done using lysis centrifugation technique followed by subculturing onto the modified Lowenstein-Jenson medium (LJ-1) and Selective Kirchner's medium followed by subculturing onto the modified Lowenstein- Jenson medium (LJ-2, LJ-3). Results: Of the 15 (16.2%) subjects with evidence of mycobacteremia in 4 (26.7%) blood was the first/ only source of diagnosing TB. Among 80 patients with clinical diagnosis of TB whether supported by laboratory tests or not, 14 (17.5%) had mycobacteraemia. Among the 21 HIV infected patients with laboratory proven TB, 9 (43%) had mycobacteraemia. Interpretation & conclusion: Blood culture appears to be a useful additional test to diagnose TB in personss with HIV infection. In patients without HIV infection, but with clinical picture compatible with TB, blood culture for mycobacteraemia may occasionally help in the diagnosis. We recommend the use of the lysis centrifugation technique followed by direct smear of the sediment along with inoculation of the sediment into both modified Lowenstein-Jenson medium and the Selective Kirchner's medium with subsequent subculturing onto the modified Lowenstein-Jenson medium for mycobacterial blood culture for detecting mycobacteraemia

Synthesis and Characterisation of Bis-(chloromethyl) Oxetane, its Homopolymer and Copolymer with Tetrahydrofuran

Bis-(chloromethyl) oxetane (BCMO) was synthesised from pentaerythritol by chlorination,followed by ring closure. It was polymerised using BF3-etherate and butanediol system, similarlythe BCMO–THF (tetrahydrofuran) copolymer was also synthesised. The monomers and thepolymers were characterised by IR, 1H-NMR and molecular weight. Flame retardant propertiesof the poly-BCMO were also investigated

TEX: The New Insensitive High Explosive

Insensitive high explosive 4, 10-dinitro-2,6,8, 12-tetraoxa-4, 10-diazatetracyclo (5.5.0.0.5,9 03,11) dodecane (TEX) has been synthesised by an improved laboratory-scale process using 93 per cent to 96 per cent nitric acid as nitrating agent. Characterisation of the product was done based on its physical constants, infrared, differential thermal analysis, and mass spectral studies. Explosive and ballistic parameters of TEX containing formulations were computed using Becker-Kistiakowsky-Wilson (BKW) code and NASA Chemical Equilibrium Composition- 71 programme, respectively. Semi-empirical quantum mechanical calculations using the parametric model 3 (PM3) method have been carried out for the TEX molecule. The optimised geometrical parameters and heats of formation were obtained from semi-empirical PM3

Synthesis and Characterisation of Bis-azido Methyl Oxetane and its Polymer and Copolymer with Tetrahydrofuran

Bis-azido methyl oxetane (BAMO) was synthesised from pentaerythritol in two steps. Pentaerythritol was chlorinated to yield a mixture of mono, di, tri and tetra chloro compounds. The trichloro compound on ring closure gives bis-chloro methyl oxetane (BCMO). It was reacted with sodium azide in aqueous medium to obtain BAMO. The latter was polymerised using BF3 etherate catalyst and 1,4-butanediol initiator. Similarly, the BAMO- THF copolymer was also synthesised. All the monomers and polymers were characterised by IR, 1H-NMR, 13C-NMR, and refractive index. The polymers were also characterised for molecular weight, hydroxyl value, etc. Thermal analysis showed that both polymers degrade exothermically with T max of 237 °C for poly BAMO and 241°C for BAMO- THF copolymer with activation energy of 39 kcal/mol and 40 kcal/mol, respectively. Explosive properties like impact and friction sensitivity of BAMO and the other polymers were also determined

Explosive Nitrotriazolone Formulates

Nitrotriazolone has been synthesised and fully characterised. This explosive was found to exhibit self-binding properties forming pellets at different loads. The compression strength of these pellets were in the range 80-128 kgf/cm2 under one to three tonne/cm2 load. Other pressable formulations containing nitrotriazolone have also been successfully prepared. A composition comparable to composition B was also prepared using nitrotriazolone and trinitrotoluene (60:40). Mechanical properties and insensitivity of this new composition were found to be superior

Low temperature elastic behaviour of As-Sb-Se and Ge-Sb-Se glasses

The ternary glasses of arsenic and germanium with antimony and selenium can be prepared in large sizes for optical purposes. The elastic behaviour of eight compositions of each glass has been studied down to 4·2 K using a 10 MHz ultrasonic pulse echo interferometer. The glasses have a normal elastic behaviour, with the velocities gradually increasing as the temperature is lowered. An anharmonic solid model of Lakkad satisfactorily explains the temperature variations. The elastic moduli of Ge xSb10Se90-x glasses increase linearly as the Ge content is increased up to 25 at. % and beyond this the increase is nonlinear. (AsSb)40Se60 glasses show a linear increase in elastic moduli with increasing Sb content. The elastic moduli of AsxSb15Se85-x glasses exhibit a drastic change near the stoichiometric composition As25Sb15Se60. These behaviours have been qualitatively explained on the basis of the structural changes in glasses

Assessment on the Use of High Capacity “Sn4_{4}P3_{3}”/NHC Composite Electrodes for Sodium-Ion Batteries with Ether and Carbonate Electrolytes

This work reports the facile synthesis of a Sn–P composite combined with nitrogen doped hard carbon (NHC) obtained by ball-milling and its use as electrode material for sodium ion batteries (SIBs). The “Sn$_{4}$P$_{3}$”/NHC electrode (with nominal composition “Sn$_{4}$P$_{3}$”:NHC = 75:25 wt%) when coupled with a diglyme-based electrolyte rather than the most commonly employed carbonate-based systems, exhibits a reversible capacity of 550 mAh g$_{electrode}$$^{−1}$ at 50 mA g$^{−1}$ and 440 mAh g$_{electrode}$$^{−1}$ over 500 cycles (83% capacity retention). Morphology and solid electrolyte interphase formation of cycled “Sn$_{4}$P$_{3}$”/NHC electrodes is studied via electron microscopy and X-ray photoelectron spectroscopy. The expansion of the electrode upon sodiation (300 mAh g$_{electrode}$$^{−1}$) is only about 12–14% as determined by in situ electrochemical dilatometry, giving a reasonable explanation for the excellent cycle life despite the conversion-type storage mechanism. In situ X-ray diffraction shows that the discharge product is Na$_{15}$Sn$_{4}$. The formation of mostly amorphous Na$_{3}$P is derived from the overall (electro)chemical reactions. Upon charge the formation of Sn is observed while amorphous P is derived, which are reversibly alloying with Na in the subsequent cycles. However, the formation of Sn$_{4}$P$_{3}$ can be certainly excluded