Lattice Inclusion of Copper Ions in Ammonium Perchlorate through Co-crystallization: Impact on Lattice, Physical, and Thermal Characteristics.

Ammonium perchlorate (AP) is an important oxidizer extensively used in composite solid propellants. Any alterations in the lattice configuration of AP could bring in a dramatic change in its physical, thermal, and ballistic characteristics though the basic thermodynamic properties could remain unaltered. In this work, we attempt to dope AP with copper nitrate through co-crystallization and examine its impact on the lattice, physical, and thermal characteristics. The effect of copper ion on the crystal morphology, bulk density, friability, moisture content, and the decomposition behavior is compared with normal propellant-grade AP. The incorporation of copper ion into AP resulted in an increase in bulk density and aspect ratio and a marginal decrease in the average particle size. The shape factor remained intact. The presence of copper ion remarkably decreased both the low- and high-temperature decomposition and reduced the activation energy for both stages, confirming the catalytic nature of copper-doped AP.

Stability of the Liquid Water Phase on Mars: A Thermodynamic Analysis Considering Martian Atmospheric Conditions and Perchlorate Brine Solutions.

The stability of the liquid water phase on Mars has been examined on the basis of fundamental thermodynamic principles. The analysis considers the atmospheric pressure and temperature conditions prevalent on Mars. Because of the very low atmospheric pressure on Mars, water cannot exist in the liquid form. However, salt dissolution can reduce the freezing point and elevate the boiling point of aqueous solutions. This is interesting in the light of the discovery of perchlorate, sulphate, sodium, potassium, and calcium ions over the Martian surface. The effect of different perchlorate salts on the freezing and boiling points of water while considering their saturation solubility under varying ionic conditions is key to this analysis. It is shown that under an average atmospheric pressure of 600 Pa, the saturated solution of sodium perchlorate (NaClO4) is stable in the liquid phase in the temperature range between 240 and 275 K. The triple point of water under this condition is shifted to 269 K with a saturation solubility of 14.4 mass % of the salt. However, a saturated solution of magnesium perchlorate (Mg(ClO4)2) renders this temperature range wider from 198 to 296 K, with the triple point being located at 269 K (salt saturation at 13.5 mass % salt). In case the water is contaminated with a mixture of these salts, an increased stability is predicted for liquid water down to 180 K and up to at least 298 K. This is caused by the increased ionic strength that enhances the freezing point depression and boiling point elevation of the solution. Thus, in the extreme and uneventful conditions of saturation by mixtures of salts, liquid water can be stable on Mars between 180 K and at least up to 298 K. Below this temperature, water exists as a glacier and above, as steam only.

Maleic acid modified cellulose for scavenging lead from water.

Macro, micro and nano fibrillary cellulose with sodium maleate groups was synthesized by the reaction of cellulose with maleic anhydride followed by sodium exchange of protons. In the present work, we demonstrate that these carboxylic groups act as chemisorbants towards toxic heavy metal ions present in contaminated water. The effects of the operating parameters such as resident time, temperature, pH, ion concentration and ion nature on chemisorbability were estimated for a given cellulose carboxylate. The kinetic results for the chemisorption of Pb2+ ion were indicative of an intra particle diffusion model and pseudo second order reaction. The chemisorption is well explained by a Freundlich isotherm model showing a multilayer chemisorption, heterogeneous surface and interaction between chemisorbed molecules. The chemisorption capability was enhanced upon decreasing the dimension of the cellulose fibril. The efficiency depended also on the nature of metal ions, dictated by the stability of the geometry of the resultant complex. The maximum chemisorption capacities of macro, micro and nano forms of sodium cellulose-maleate for Pb2+ were 20 mg/g, 40 mg/g and 115 mg/g, respectively at pH of 5.5. The ion exchanged nano-cellulose maleate could be regenerated by sodium chloride solution without loss of efficiency even after 7 cycles.

A robust, melting class bulk superhydrophobic material with heat-healing and self-cleaning properties.

Superhydrophobic (SH) materials are essential for a myriad of applications such as anti-icing and self-cleaning due to their extreme water repellency. A single, robust material simultaneously possessing melt-coatability, bulk water repellency, self-cleanability, self-healability, self-refreshability, and adhesiveness has been remaining an elusive goal. We demonstrate a unique class of melt-processable, bulk SH coating by grafting long alkyl chains on silica nanoparticle surface by a facile one-step method. The well-defined nanomaterial shows SH property in the bulk and is found to heal macro-cracks on gentle heating. It retains wettability characteristics even after abrading with a sand paper. The surface regenerates SH features (due to reversible self-assembly of nano structures) quickly at ambient temperature even after cyclic water impalement, boiling water treatment and multiple finger rubbing tests. It exhibits self-cleaning properties on both fresh and cut surfaces. This kind of coating, hitherto undisclosed, is expected to be a breakthrough in the field of melt-processable SH coatings.

Upper airway obstruction in Guillain-Barré syndrome.

We report a patient with bilateral vocal cord paralysis and upper airway obstruction following Guillain-Barré syndrome (GBS). A permanent tracheostomy was necessary to maintain adequate ventilation and to prevent alveolar hypoventilation. Despite abduction paralysis, the patient talks normally.

Folate-mediated incorporation of ring-2-carbon of histidine into nucleic acids: influence of thyroid hormone.

Folate-mediated incorporation of [ring-2-14C]histidine into DNA and its modulation under thyroid stress have been studied. Both hyperthyroidism and hypothyroidism decrease the folate-mediated incorporation of the one-carbon unit derived from histidine into DNA significantly, resulting in growth retardation. In concurrence with previous reports, in vivo oxidation of histidine is decreased in hyperthyroidism and increased in hypothyroidism. 5,10-Methylenetetrahydrofolate reductase levels are elevated in hyperthyroidism and decreased in hypothyroidism, whereas methionine synthase levels are decreased in hyperthyroidism and increased in hypothyroidism. It is discussed how in both hyperthyroidism and hypothyroidism folate cofactor-mediated reactions are adversely affected.

Symptomatic epidural lipomatosis secondary to obesity. Case report.

The authors present a case of thoracic spinal cord compression secondary to epidural lipomatosis in an obese patient. This patient represents the 10th case of epidural lipomatosis secondary to simple obesity reported in the literature. The diagnosis is based on three criteria: 1) medical history and physical examination consistent with segmental spinal cord compression; 2) epidural fat thickness greater than 7 mm in the region of compression, based on magnetic resonance imaging (preferred) or computerized tomographic imaging; and 3) a height-to-weight ratio greater than 27.5 kg/m2. This specific correlation between epidural fat thickness measurement and calculation of height-to-weight ratio has not previously been reported. Surgical decompression through a posterior laminectomy and excision of excess epidural fat resulted in immediate reversal of the patient's symptoms. Knowledge of the association of epidural lipomatosis with obesity in the absence of glucocorticoid imbalance is important in discerning what may be an underrecognized syndrome.

The concurrence of multiple sclerosis and amyotrophic lateral sclerosis.

We report the clinical and pathological findings of the unusual combination of two idiopathic central nervous system diseases, multiple sclerosis and amyotrophic lateral sclerosis in a 56 year old physician with a twenty-seven year history of a disease initially characterized by relapses and remissions, followed by an eight year quiescent period. During the last year of life there was rapid deterioration with development of generalized weakness, atrophy, weight loss and fasciculations of body and tongue, and associated difficulty with swallowing and sudden respiratory failure. The autopsy confirmed characteristic "burned out" plaques of multiple sclerosis and anterior horn cell and axonal degeneration of amyotrophic lateral sclerosis.

Two cases of recovery of kilocurie sources fallen from telegamma units.

Recently, two incidents involving the fall of kilocurie sources from telegamma units during repairs occurred in India. In one case it was a 60Co source of activity 222 TBq (6,000 Ci) and in the other case, it was a 137Cs source of activity 75.85 TBq (2,050 Ci). The line of action planned for the recovery of the sources was to cover the sources with large quantities of lead shots sent through a sloping pipe, thereby reducing the exposure rate. Once this was arranged, the workers could go inside for further retrieval action. An aluminium container was designed and positioned over the source drawer and lead shots were poured into this container. The retrieval operation was executed as planned but with slight modifications as necessitated at the sites. The collective effective dose for the recovery of the first source was approximately 0.07 person-sievert (7 person-rem) and for the second one was < 0.01 person-sievert (1 person-rem).

An indirect role of vitamin B12 in regulation of thymidylate synthase in Lactobacillus leichmannii.

Vitamin B12 augments thymidylate synthase function in L. leichmannii by facilitating indirectly the availability of suitable nonmethylpolyglutamylfolate cofactors. This is effected by the demethylation of trapped methyltetrahydrofolates, catalysed by a vitamin B12 requiring methionine synthase. Deoxyuridine supplemented cells, lacking in B12, have decreased levels of methionine synthase and thymidylate synthase. Addition of active and inactive conjugase preparation as a source of mono and polyglutamylfolates indicated that the latter are the preferred cofactors for thymidylate synthase.

Possible involvement of superoxide radical in biochemical lesions induced by nitrous oxide.

Inactivation of methionine synthase (MS) by nitrous oxide (N2O) administration to animals and man has been postulated to be mediated by hydroxyl radical (OH). An alternate mechanism has been proposed which involves superoxide radical (O2.-) originating from N2O in the inactivation of MS by OH that may arise from O2.- through Fenton/Haber-Weiss reaction. Rats inhaling a mixture of N2O:O2 (1:1) for 5 hr showed inactivation of MS in liver to nearly 90% which could not be reversed by prior administration of either dimethyl sulfoxide (DMSO) or sodium benzoate. Pretreatment of rats with superoxide dismutase (SOD) at two doses, 0.1 mg and 3.5 mg/100 g body weight, retarded the in vivo inactivation of MS by N2O, to 76% and 47% respectively. In vitro inactivation of MS with N2O could not be retarded by DMSO or Na-benzoate, or either exogenous SOD or catalase.

Effect of nitrous oxide and methionine on hepatic S-adenosylmethionine levels and in vivo histidine oxidation in rats.

Nitrous oxide (N2O) decreased in vivo oxidation of histidine in rats fed a basal diet marginally deficient in methionine, although hepatic levels of S-adenosylmethionine (AdoMet) were not significantly altered. Excess dietary methionine increased hepatic levels of AdoMet and increased histidine oxidation. However, it did not protect histidine oxidation when the rats were treated with N2O. Parenteral administration of methionine greatly increased hepatic levels of AdoMet and increased histidine oxidation in normal and N2O treated rats. This indicates that when hepatic levels of AdoMet are greatly elevated by administration of methionine, N2O does not affect in vivo histidine oxidation.

Altered metabolism of folates and lipids in hyperthyroid and hypothyroid rats.

Effect of excess folate on the metabolism of folate and plasma lipids in thyroid stressed animals was studied. Administration of excess dietary folate to hyperthyroid rats did not affect the decreased in vivo histidine oxidation in these animals, but it increased the hepatic tetrahydrofolate content. Hypothyroid rats had higher plasma total cholesterol (TC), high density lipoprotein cholesterol (HDLC) and trigylcerides (TG) with no change in post heparin lipolytic activity (PHLA). In hyperthyroidism both TC and HDLC were decreased in plasma and PHLA levels were elevated. On administration of excess dietary folate to hyperthyroid rats HDLC levels were not altered but PHLA and TC levels became near normal, while TG levels remained elevated.

Folylpolyglutamate synthetase in Lactobacillus leichmannii: in vitro synthesis and characterization of polyglutamylfolates.

In vitro synthesis of folylpolyglutamates by folylpolyglutamate synthetase from Lactobacillus leichmannii has been studied and optimal conditions for enzyme activity determined. It is found that while ATP (5 mM) is essential for the synthesis of folylpolyglutamates homocysteine augments the same. Replacement of vitamin B12 (2 ng/ml) with deoxyuridine (20 micrograms/ml) in growth medium does not alter the enzymatic parameters studied. DEAE-cellulose column chromatography of in vitro synthesised folylpolyglutamates indicates that folylpolyglutamate synthetase of L. leichmannii can synthesize polyglutamates up to a chain length of four glutamate residues.