Transient DSC,a Novel and Rapid Method for Assessing Pharmaceutical Powder Compacts

The previously described method involving the use of transient DSC was applied to pharmaceutical powder compacts and to ceramic powder compacts. The samples were prepared by compressing powders of pentaerythritol tetraacetate and two kinds of alumina powder (differing in particle size distribution) up to a pressure of 20 MPa by using a jig. For pentaerythritol tetraacetate, a linear relationship was obtained between the parameter obtained by DSC and the compaction pressure. This revised version was published online in August 2006 with corrections to the Cover Date.     

Application of the sequential gradient-restoration algorithm to thermal convective instability problems

The problem of the thermal stability of a horizontal incompressible fluid layer with linear and nonlinear temperature distributions is solved by using the sequential gradient-restoration algorithm developed for optimal control problems. The hydrodynamic boundary conditions for the layer include a rigid or free upper surface and a rigid lower surface. The resulting disturbing equations are solved as a Bolza problem in the calculus of variations. The results of the study are compared with the existing works in the literature.The authors acknowledge valuable discussions with Dr. A. Miele.     

On some measurements of the propagation properties of thermal waves in the Nb-H and Ta-H systems

Summary By means of an experimental technique based on a nonsteady-state method,i.e. on the propagation of thermal waves, we have measured at room temperature for oscillation frequencies between 6 and 30 mHz the thermal diffusivity, the lateral thermal-loss coefficient and the ?fractional heat loss? in Nb and Ta wires as a function of hydrogen doping. The appearance of hydride formation and precipitation notably changes the behaviour of these quantities. From these measurements it was also possible to calculate the propagation velocity and attenuation coefficient of thermal waves. It was found that the increase of the hydrogen concentration in the solid solution produces a gradual decrease in the velocity and increase in the attenuation coefficient until the solubility limit is reached. For larger hydrogen concentrations, the velocity showed a tendency to increase towards the value of the pure metal, while the attenuation coefficient decreased below the value of the pure metal. These results as a whole appear quite promising for studying the properties of hydrogenated systems. This work was supported by the Gruppo Nazionale di Struttura della Materia of the Consiglio Nazionale delle Ricerche and by the Centro Interuniversitario di Struttura della Materia of the M.P.I., Roma (Italia).     

Lattice parameter and thermal expansion of CsCl and CsBr by x-ray powder diffraction. II. Thermal expansion of CsBr from room temperature to 78.2 °K

The lattice parameters of CsBr at eight different temperatures from room temperature to 78.2 °K were measured and the true lattice parameters were obtained by the least squares method using the Nelson-Riley extrapolation function. Using these parameters the thermal expansion coefficients of CsBr were estimated at each temperature by fitting them into a cubic polynomial involving temperatureT. Theα _T thus obtained were compared with the values of earlier workers who used an interferometric technique and the agreement was found to be good.     

Polymers from a levopimaric acid–acrylonitrile Diels–Alder adduct: Synthesis and characterization

The Diels–Alder adduct of levopimaric acid with acrylonitrile was efficiently prepared from resin acids. Excellent addition reaction yields (ca. 95%) were obtained. The adduct was converted into polyamides by polycondensation with diamines. When the same adduct was subjected to a dehydrodecarboxylation reaction, a novel ketone dinitrile derivative was obtained. This trifunctional product was also converted into polyamides by polycondensation with diamines. When the ketone dinitrile was hydrolyzed in the presence of alkalies and the reaction product was chlorinated, a ketone diacid chloride was obtained. A polyester was synthesized by the polycondensation of the diacid chloride with a diol. The structures of the Diels–Alder adduct, ketone dinitrile derivative, ketone diacid chloride, and polymers were established by means of elemental analysis, IR and NMR spectroscopy, and molecular weight determinations. Both the polyamides and the polyester were low‐molecular‐weight polymers soluble in polar solvents. The thermal behavior of the monomers and polymers was evaluated by thermogravimetric analysis. The thermal studies showed that the polymers were fairly thermostable substances, except the polyester, which appeared to be a substance with good thermal stability. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6308–6322, 2005     

Thermo‐oxidative degradation of HDPE as a function of its crystalline content

The composition, the thermal properties, and the kinetics of the thermo‐oxidative degradation of high‐density polyethylene (HDPE) were studied as a function of the increasing crystalline fraction, which resulted from the selective extraction of the amorphous part, through digestion by immersion in fuming nitric acid (HNO₃) for different periods of time. The chemical and thermodynamic changes in HDPE, brought about by digestion in nitric acid for different periods of time, are discussed. Changes in the chemistry and microstructure of the HDPE, as a function of acid treatment for different periods of time, were studied using infra‐red spectroscopy (FTIR), gel permeation chromatography (GPC), and thermal analysis (DSC and TGA), as well as scanning electron microscopy (SEM). These studies were carried out as a function of the extracted amorphous fraction of HDPE samples via digestion in HNO₃. These studies showed that in the first stages of the acid chemical attack, the amorphous part first undergoes a chemical modification and then dissolves into the strong acid medium. The total crystalline fraction apparently decreases during the first stages of the chemical attack and then increases as the amorphous part is extracted. TGA results show that as the selective extraction of the amorphous part occurs, there is a displacement of the thermo‐oxidative degradation toward higher temperatures. The kinetics of the thermo‐oxidative degradation as a function of the extraction of the amorphous part was followed according to the Horowitz‐Metzger method, and it was found that as the concentration of the crystalline fraction increases, the activation energy for the thermo‐oxidative degradation increases. SEM studies show that the extraction of the amorphous part does not affect the size of the crystalline lamellar thickness of HDPE. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1906–1915, 2009     

Solvent-free Synthesis, Crystal Structure and Thermal Stability of Ionic Liquid 1-Hexadecyl-3-methylimidazolium Bromide

Ionic liquid 1-hexadecyl-3-methylimidazolium bromide [C16mim]Br was synthesized by solvent-free alkylation of N-methylimidzole with hexadecyl bromide. A large transparent single crystal of 1-hexadecyl-3-methylimidazolium bromide monohydrate （[C16mim]Br·H2O）, 4 mm in length, was firstly obtained in the water-trichloromethane-toluene growth system （Vwater＇Vtrichloromethane＇Vtoluene = 0.1：1：2）. The crystal structure was determined by single-crystal X-ray diffraction method. It crystallizes in the triclinic system, space group P1, with a = 5.4962（15）, b = 7.839（2）, c = 27.279（8） A, α = 94.375, β = 91.500, γ = 101.999°, Z = 2, V = 1145.2（5） A3, C20H41BrN2O, Mr = 405.46, Dc = 1.176 Mg/m3, μ = 1.804 mm^-1, F（000） = 436, the final R = 0.0523 and wR = 0.1345. The 3D supramolecular structure is constructed through weak interactions between imidazolium cations, Br- anions and lattice water molecules. The long alkyl chain to the imidazolium ring and lattice water molecules play an important role in the self-assembly process. Moreover, it is proposed that [C16mim]Br in water has aggregation behavior and the possible self-assembled structure is the interdigitated pattern. Finally, thermal stability of [C16mim][Br]·H2O was also studied by DSC and TGA analysis.     

Generation of Multi-ion Graph States with Trapped Ions in Thermal Motion

We propose a scheme for generating multi-ion graph states using many trapped ions in thermal motion. Our generation scheme is insensitive to external state since the interaction between ions and laser fields does not involve the external degree of freedom. The scheme can be well realized within the current experimental technique.     

Laccase‐catalyzed polymerization of lignocatechol and affinity on proteins of resulting polymers

For the synthesis of a new biologically functional polymer from a natural resource by an environment‐friendly method, the laccase‐catalyzed polymerization of a lignin‐based macromonomer, lignocatechol, was carried out for the first time in ethanol–phosphate buffer solvent system to give crosslinked polymers in good yields. Lignocatechol was prepared by the phase separation system of lignin and catechol in aqueous sulfuric acid. The copolymerization was also performed with urushiol to afford the corresponding copolymers in high yields. The polymerization mechanism was estimated by the IR and pyrolysis GC‐MS measurements, suggesting that the polymerization proceeded mainly at the catechol ring through a quinone radical intermediate. The thermal properties were measured by the DSC, TG, and TMA analyses, indicating that the polymers had high thermal stabilities because of the crosslinked structures. In addition, it was found that the resulting polymers had the affinity of bovine serum albumin (BSA) and glucoamylase. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 824–832, 2009