A dilute bootstrap percolation: Lattice model for unresponsiveness in T-cell immunology

The biased majority rule of cellular automata takes a spin up if and only if at least two of its four nearest neighbors on the square lattice are up. We generalize this type of bootstrap percolation by introducing quenched site dilution as well as a random birth and decay process. Our Monte Carlo simulations then give first-order transitions qualitatively similar to our results from meanfield reaction equations describing the induction of T-cell unresponsiveness in the immune system.     

Instrumentation and calibration of the Calvet calorimeter

The original Calvet calorimeter, made from aluminum block, were instrumented. The cells for the solution calorimetry measurement have been projected and constructed. The calibration of calorimeter was performed by measurement of the dependence of reference material on temperature and the influence of mechanical events on thermograms. The enthalpies of solution in water and 0.01 M HCl were investigated for chlorides and bromides of alkali metals (Na···Cs), PrBr₃ and Rb₃PrBr₆. The enthalpies of solution of alkali halides have been compared to the reference data obtained for infinite solution. The decomposition of Rb₃PrBr₆ at temperatures lower than 399 K has been stated. The enthalpy of solution PrBr₃ at 298.15 K has been determined.     

Solubility of Lanthanide Chlorides ( Ln Cl3) in Alkali Metal Chlorides ( M Cl): Thermodynamics and Electrical Conductivity of the M 3 Ln Cl6 Compounds

 Several compounds may exist in LnCl₃–MCl mixtures. Those corresponding to the M ₂ LnCl₅ and MLn ₂Cl₇ stoichiometries are formed in a few systems only, with diverse stability strongly dependent on both the corresponding lanthanide and alkali metal. On the other hand, M ₃ LnCl₆ that occur in most systems have a far larger stability range and melt congruently. These latter compounds were investigated in the present work by differential scanning calorimetry and electrical conductivity measurements. The thermodynamic and transport properties were correlated to structural features and related to the mechanism of compound formation.     

Phase diagram of the TbBr(3)-RbBr binary system: thermodynamic and transport properties of the Rb(3)TbBr(6) compound

Phase equilibria in the TbBr3-RbBr binary system were established from differential scanning calorimetry (DSC) measurements. This binary system is characterized by two compounds, namely Rb3TbBr6 and RbTb2Br7, and two eutectics located at the TbBr3 mole fractions, x = 0.117 (728 K) and x = 0.449 (718 K), respectively. Rb3TbBr6 undergoes a solid-solid phase transition at 728 K and melts congruently at 1047 K with the related enthalpies 7.8 and 58.7 kJ mol(-1), respectively. RbTb2Br7 melts incongruently at 803 K. It undergoes also a solid-solid phase transition at 712 K, a temperature very close to that (718 K) of the second eutectic, and much attention was paid in evidencing and separating these transition and eutectic effects. Separate investigations of the thermodynamic and transport properties were performed on the Rb3TbBr6 compound. These heat capacity and electrical conductivity experimental results suggest an order-disorder mechanism in the alkali-metal cation sublattice whereas the TbBr6 octahedra, forming the anionic sublattice, retain their normal lattice positions.     

Characterization of the coating layer on glass fibre used as reinforcement in polyepoxyde matrix

R glass fibre for the reinforcement of epoxy matrices has been coated with epoxy prepolymer (as film-former or sizing agent) or γAPS aminosilane (as coupling agent) or a mixture of these two products. The structure of the coating layer and its interaction capabilities with fibre and matrix have been studied by coupled calorimetry-gravimetry of sorption of different model reactants and by Fourier Transform infra-red analysis.     

The influence of RAFT on the rates and molecular weight distributions of styrene in seeded emulsion polymerizations

Seeded emulsion polymerizations of styrene in the presence of two reversible addition–fragmentation chain‐transfer (RAFT) agents were studied. We designed the seed to be small to observe the effects of exit and, we made the seed of poly(methyl methacrylate) so that the molecular weight distributions of poly(styrene) by gel permeation chromatography could be obtained independently by UV detection. The rates were significantly retarded by the presence of a RAFT agent, with the retardation being greater with an EMA RAFT agent [2‐(ethoxycarbonyl)propyl‐2‐yl dithiobenzoate] than with a cumyl RAFT agent (2‐phenylprop‐2‐yl dithiobenzoate). We propose that exit from the particles after fragmentation was the main cause of retardation. In addition, the number‐average molecular weight and polydispersities (broad) did not resemble the characteristic living behavior found in bulk or solution. This was a result of the continuous transportation of RAFT agent into the particles during interval II and the transportation of a small amount during interval III. A conspicuous red layer was also observed at the beginning of the polymerization. The red layer consisted of low molecular weight dormant species swollen with monomer. Once the switch from interval II to interval III occurred, the low molecular weight species coalesced to form a red coagulant. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3864–3874, 2000     

Protogenkwanin 4′-glucoside,a new type of natural flavonoid with a non aromatic B-ring

From fertile sprouts of $\text{Equisetum arvense}$ L. (Equisetaceae) a flavonoid has been isolated and called protogenkwanin 4′-glucoside (2-(4-β-D-glucosyloxy-1-hydroxy-2,5-cyclohexadienyl)-5-hydroxy-7-methoxy chromone). Its structure has been established on the basis of chemical and spectroscopical evidences.     

Synthesis and Antitubercular Evaluation of N‐Arylpyrazine and N,N′‐Alkyl‐diylpyrazine‐2‐carboxamide Derivatives

Two series of pyrazinamide (PZA) derivatives have been synthesized and evaluated for their in vitro antibacterial activity against Mycobacterium tuberculosis H37Rv. Some compounds exhibited minimum inhibitory concentration activity of 50–100 μg/mL, greater than the first line antituberculosis drug PZA in Alamar Blue assay (>100 μg/mL). The obtained activities can be considered promising results, which characterizes these compounds as good start points to development of new antitubercular agents.