Tetrahydrofuran Clathrate Hydrate Formation

We report on the formation of tetrahydrofuran clathrate hydrate studied by x-ray Raman scattering measurements at the oxygen K edge. A comparison of x-ray Raman spectra measured from water-tetrahydrofuran mixtures and tetrahydrofuran hydrate at different temperatures supports stochastic hydrate formation models rather than models assuming hydrate precursors. This is confirmed by molecular dynamics simulations and density functional theory calculations of x-ray Raman spectra. In addition, changes in the spectra of tetrahydrofuran hydrate with temperatures close to the hydrate's dissociation temperature were observed and may be connected to changes in hydrate's local structure due to the formation of hydrogen bonds between guest and water molecules.

Effect of favorable pressure gradient on transitional spot formation rate

The calculation of the transitional boundary layer requires estimates of the extent of the transition zone, which in turn depends on the rate at which turbulent spots are formed. This rate has been found to scale with local boundary layer thickness and viscosity, and the resulting nondimensional group (called crumble) is a function of the pressure gradient, among other parameters. Available experimental data are analyzed to show that the crumble increases slowly with increasing favorable pressure gradients, being about four times as large as in constant-pressure flow when the Thwaites pressure gradient parameter at the effective origin of the resulting turbulent boundary layer is 0.1 and when transition is driven by free-stream turbulence.

Evidence for the formation of a known toxin, P-cresol, from menthofuran

Menthofuran (II, 4,5,6,7-tetrahydro-3,6-dimethyl benzofuran), the proximate toxin of R-(+)-pulegone (I), was administered orally to rats (200 mg/kg of body weight/day) for three days and the urinary metabolites were investigated. Among the several metabolites formed, two of them viz. 4-Hydroxy-4-methyl-2-cyclohexenone (VII) and p-cresol (VIII) were indentified. In support of the formation of these metabolites, it has been demonstrated that phenobarbital induced rat liver microsomes readily convert 4-methyl-2-cyclohexenone (V) to 4-hydroxy-4-methyl-2-cyclohexenone (VII) and p-cresol (VIII) in the presence of NADPH and O2. Possible mechanism for the formation of these two metabolites (VII, VIII) from menthofuran (II) has been proposed.

Formation of lead pyrophosphate glass and the role of anion disproportionation

Thermal, spectroscopic and electrical properties of lead pyrophosphate glass prepared by melt quenching have been examined. A model based on the structural disproportionation of the P2O 7 4− ions has been proposed and is shown to consistently explain all the observations. The equilibrium of various anionic species has been discussed on the basis of their electronegativities which are in turn related to their basicities.

One pot synthesis of polycyclic oxygen aromatics. Part III mechanism of formation

Reaction of 6-Image -butyl-1-bromomethyl-2-(2-tetrahydropyranyloxy)-naphthalene2c with tetrachlorocatechol (TCC) in acetone in presence of K2CO3 gave diastereomers 6c and 7c. A mechanism (Scheme-1) invoking the base induced cleavage of the pyranyl ether 2 to 1,2-naphthoquinone-1-methide 8 as the first step has been postulated. The cleavage of the pyranyl ether linkage in 2 to give dimers 4 and 5 of 1,2-naphthoquinone-1-methide has been demonstrated with different bases. 1,2-Naphthoquinone-1-methide 8, thus generated, undergoes Michael addition with TCC followed by elimination of chloride ions to give a diketone, which further undergoes aldolisation with acetone to give diastereomers 6 and 7. Michael reaction of 8, generated Image from pyranyl ethers 2a-c, with tetrabromocatechol (TBC) under similar-reaction conditions gave the expected monobromo compounds 6h, 6i, 6k, 7n, 7n and 7q. The last step in the proposed mechanism, Image ., aldolisation has also been demonstrated using different ketonic solvents. Thus, reaction of 2a-c with TCC/TBC in diethyl ketone/methyl ethyl ketone under similar reaction conditions gave the expected compounds 6 and 7.

Genomic alterations in Myeloproliferative Neoplasms and Myelodysplastic Syndromes

Myeloproliferative neoplasms (MPN) and myelodysplastic syndromes (MDS) are a heterogeneous group of clonal hematopoietic disorders whose etiology and molecular pathogenesis are poorly understood. During the past decade, enormous developments in microarray technology and bioinformatics methods have made it possible to mine novel molecular alterations in a large number of malignancies, including MPN and MDS, which has facilitated the detection of new prognostic, predictive and therapeutic biomarkers for disease stratification. By applying novel microarray techniques, we profiled copy number alterations and microRNA (miRNA) expression changes in bone marrow aspirate and blood samples. In addition, we set up and validated an miRNA expression test for bone marrow core biopsies in order to utilize the large archive material available in many laboratories. We also tested JAK2 mutation status and compare it with the in vitro growth pattern of hematologic progenitors cells. In the study focusing on 100 MPN cases, we detected a Janus kinase 2 (JAK2) mutation in 71 cases. We observed spontaneous erythroid colony growth in all mutation-positive cases in addition to nine mutation negative cases. Interestingly, seven JAK2V167F negative ET cases showed spontaneous megakaryocyte colony formation, one case of which also harbored a myeloproliferative leukemia virus oncogene (MPL) mutation. We studied copy number alterations in 35 MPN and 37 MDS cases by using oligonucleotide-based array comparative hybridization (array CGH). Only one essential thrombocythemia (ET) case presented copy number alterations in chromosomes 1q and 13q. In contrast, MDS cases were characterized by numerous novel cryptic chromosomal aberrations with the most common copy number losses at 5q21.3q33.1 and 7q22.1q33, while the most common copy number gain was trisomy 8. As for the study of the bone marrow core biopsy samples, we showed that even though these samples were embedded in paraffin and underwent decalcification, they were reliable sources of miRNA and suitable for array expression analysis. Further, when studying the miRNA expression profiles of the 19 MDS cases, we found that, compared to controls, two miRNAs (one human Epstein-Barr virus (miR-BART13) miRNA and one human (has-miR-671-5p) miRNA) were downregulated, whereas two other miRNAs (hsa-miR-720 and hsa-miR-21) were upregulated. However, we could find no correlation between copy number alterations and microRNA expression when integrating these two data. This thesis brings to light new information about genomic changes implicated in the development of MPN and MDS, and also underlines the power of applying genome-wide array screening techniques in neoplasias. Rapid advances in molecular techniques and the integration of different genomic data will enable the discovery of the biological contexts of many complex disorders, including myeloid neoplasias.

Standard Gibbs' energies of formation of BaCuO2, Y2Cu2O5 and Y2BaCuO5

The Gibbs' energies of formation of BaCuO2, Y2Cu2O5 and Y2BaCuO5 from component oxides have been measured using solid state galvanic cells incorporating CaF2 as the solid electrolyte under pure oxygen at a pressure of 1.01 x 10(5) Pa Because the superconducting compound YBa2Cu3O7-delta coexists with any two of the phases CuO, BaCuO2 and Y2BaCuO5, the data on BaCuO2 and Y2BaCuO5 obtained in this study provide the basis for the evaluation of the Gibbs' energy of formation of the 1-2-3 compound at high temperatures.

Bovine mastitis caused by coagulase-negative staphylococci : host response and bacterial factors

Coagulase-negative staphylococci (CNS) are the most common bacteria isolated in bovine subclinical mastitis in many countries, and also a frequent cause of clinical mastitis. The most common species isolated are Staphylococcus (S) chromogenes, S. simulans, S. epidermidis, and S. xylosus. One half of the intramammary infections (IMI) caused by CNS persist in the udder. The pathogenesis of IMI caused by CNS is poorly understood. This dissertation focuses on host response in experimental intramammary infection induced by S. chromogenes, S. epidermidis and S. simulans. Model for a mild experimental CNS infection was developed with S. chromogenes (study I). All cows were infected and most developed subclinical mastitis. In study II the innate immune response to S. epidermidis and S. simulans IMI was compared in eight cows using a crossover design. A larger dose of bacteria was used to induce clinical mastitis. All cows became infected and showed mild to moderate clinical signs of mastitis. S. simulans caused a slightly stronger innate immune response than S. epidermidis, with significantly higher concentrations of the interleukins IL-1beta and IL-8 in the milk. The spontaneous elimination rate of the 16 IMIs was 31%, with no difference between species. No significant differences were recorded between infections eliminated spontaneously or remaining persistent, although the response was stronger in IMIs eliminated spontaneously, except the concentration of TNF-α, which remained elevated in persistent infections. Lactoferrin (Lf) is a component of the humoral defence of the host and is present at low concentrations in the milk. The concentration of Lf in milk is high during the dry period, in colostrum, and in mastitic milk. The effect of an inherent, high concentration of Lf in the milk on experimental IMI induced with S. chromogenes was studied in transgenic cows that expressed recombinant human Lf in their milk. Human Lf did not prevent S. chromogenes IMI, but the host response was milder in transgenic cows than in normal cows, and the former eliminated infection faster. Biofilm production has been suggested to promote persistence of IMI. Phenotypic biofilm formation and slime producing ability of CNS isolates from bovine mastitis was investigated in vitro. One-third of mastitis isolates produced biofilm. Slime production was less frequent for isolates of the most common mastitis causing species S. chromogenes and S. simulans compared with S. epidermidis. No association was found between the phenotypic ability to form biofilm and the persistence of IMI or severity of mastitis. Slime production was associated with persistent infections, but only 8% of isolates produced slime.

Defective in Cuticular Ridges (DCR) of Arabidopsis thaliana, a Gene Associated with Surface Cutin Formation, Encodes a Soluble Diacylglycerol Acyltransferase

A key step in the triacylglycerol (TAG) biosynthetic pathway is the final acylation of diacylglycerol (DAG) by DAG acyltransferase. In silico analysis has revealed that the DCR (defective in cuticular ridges) (At5g23940) gene has a typical HX4D acyltransferase motif at the N-terminal end and a lipid binding motif VX(2)GF at the middle of the sequence. To understand the biochemical function, the gene was overexpressed in Escherichia coli, and the purified recombinant protein was found to acylate DAG specifically in an acyl-CoA-dependent manner. Overexpression of At5g23940 in a Saccharomyces cerevisiae quadruple mutant deficient in DAG acyltransferases resulted in TAG accumulation. At5g23940 rescued the growth of this quadruple mutant in the oleate-containing medium, whereas empty vector control did not. Lipid particles were localized in the cytosol of At5g23940-transformed quadruple mutant cells, as observed by oil red O staining. There was an incorporation of 16-hydroxyhexadecanoic acid into TAG in At5g23940-transformed cells of quadruple mutant. Here we report a soluble acyl-CoA-dependent DAG acyltransferase from Arabidopsis thaliana. Taken together, these data suggest that a broad specific DAG acyltransferase may be involved in the cutin as well as in the TAG biosynthesis by supplying hydroxy fatty acid.

The Reaction of N4P4Cl8 with Dibenzylamine: Formation of an Unusual Bicyclic Phosphazene, N4P4[N(CH2Ph)2]6(NCH2Ph), by Dealkylation

The reactions of halogenocyclotetraphosphazatetraenes N4P4X8, with nucleophiles have received little attention and only the reactions of the octachloride, N4P4Cl8, with amines have been investigated in any detail.1 Millington and Sowerby2 studied the reaction of N4P4Cl8 with dimethylamine and isolated the derivatives, N4P4Cl8-n (NMe2)n, n = 2,3,4,5,6,8;several N-methylanilino derivatives