Coalescence of polystyrene nodules in soft poly(butyl acrylate)-based films

A two-stage emulsion polymerization procedure was used in order to obtain core–shell polymer particles having a core of polystyrene (PS), covered by a shell of either pure poly(butyl acrylate) (PBA) or a methacrylic acid-functionalized PBA. Films were then cast from these latexes, and their properties were studied without further treatments (“as-dried” films), as well as after a 3 hr heat treatment intended to provoke the coalescence of PS domains (“annealed” films). “As-dried” and “annealed” film samples were studied by dynamic mechanical analysis (DMA), scanning electron microscopy (SEM) and small angle neutron scattering (SANS). DMA and SEM results, as described in previous works, showed that for unfunctionalized films, the percolated PS domains coalesced under the annealing treatment, while for the functionalized films, they did not. On the other hand, SANS results presented here showed that even in the case of functionalized films, the presence of coalescence could be detected. It was concluded that while DMA and SEM reveal large-scale modifications provoked by the heat treatment, SANS is capable of detecting very smallscale changes which do not have a direct effect on the bulk physical properties of the samples.     

Crystal structure and fast ionic conduction of TIZrF5

TlZrF₅ crystallizes in the monoclinic system with unit cell dimensions a = 8.112(1) Å, b = 7.927(3) Å, c = 7.929(1) Å, β = 123.99(1)° and space group P2₁/c (n^o 14); Z = 4. The structure was solved by conventional Patterson and Fourier methods and refined by full-matrix least-squares techniques to a conventional R of 0.057 (R_ω = 0.063). The structure consists of sheets of (ZrF₅)^? that may be described as edge-shared and corner-shared bicapped trigonal prisms (ZrF₈). The sheets run parallel to the y0z plan and are bonded together by the Tl ions which are surrounded by 12 F^? ions. The ionic conductivity of TlZrF₅ and TlHfF₅ has been investigated by complex impedance measurements and the relationships between structure and fast-ionic conduction are discussed.     

Rapid molecular typing of <Emphasis Type="Italic">Tuber melanosporum</Emphasis>, <Emphasis Type="Italic">T. brumale</Emphasis> and <Emphasis Type="Italic">T. indicum</Emphasis> from tree seedlings and canned truffles

We have developed new DNA extraction and purification procedures for investigation of mycorrhized seedlings and canned truffles. Use of these procedures on approximately 100 mg initial material enabled good sample representation. For mycorrhized seedlings, Taq polymerase inhibitors were discarded irrespective of tree species. In routine analysis we systematically used consensus primers ITS1/ITS4 to check the absence of Taq polymerase inhibitors and the presence of fungus DNA. Positive response with ITS validates other positive or negative PCR results. Absence of amplification with ITS prevents validation of other results. For canned truffles, DNA harvested from ascocarps sterilized for one and a half hours at 115°C was amplified with specific primers. We have developed consensus primers, named R12/F12, to check for the presence of amplifiable fungus DNA and the absence of Taq polymerase inhibitors. Here also, positive response with consensus R12/F12 validates other positive or negative PCR results. We have developed one primer pair specific for T. brumale and another specific for T. melanosporum. We can then characterize these two taxa, which enables the use of truffle or truffled French designations. We can also characterize T. indicum, the Asiatic black truffle that might fraudulently be sold as T. melanosporum and T. brumale. These three specific primer pairs were used independently of DNA extraction from tree seedlings or canned truffles. Our process is specific, sensitive, convenient, and quick.J.P. Douet and D. Mabru have contributed equally to this work     

Chemistry of sulfonyl isocyanates and sulfonyl isothiocyanates. X. Possible routes to substituted imidazolidinethiones and hexahydropyrimidinethiones

4-Toluenesulfonyl isocyanate (I) reacted with 2-aminoethanol and 3-amino-l-propanol to give 2:1 isocyanate/amino alcohol addition products. 1-Amino-2-propanol and I gave 1:1 and 2:1 adducts while 2-amino-2-methyl-l-propanol afforded only a 1:1 adduct. 4-Toluenesulfonyl isothio-cyanate (III) gave 1:1 adducts with 2-aminoethanol, l-amino-2-propanol and 3-amino-l-propanol, the first two of which were cyclized by concentrated sulfuric acid to 1-(4-toluenesulfonyl)-imidazoline-2-thiones and the third to 1-(4-toluenesulfonyl)hexahydropyrimidine-2-thione. A 1:2 adduct was obtained from III and 2-amino-2-methyl-l-propanol. Amino acids reacted with I and with 4-chlorobenzenesulfonyl isocyanate (II) to give N-(arylsulfonyl)-N¹-(carboxylic acid)-ureas. N-(4-Toluenesulfonyl)-N¹-(acetic acid)-urea (XVI) was converted to the methyl ester (XIX) by concentrated sulfuric acid and methanol and to water-soluble unrecoverable products by sulfuric acid alone. Glycine and III gave N-(4-toluenesulfonyl)-N¹-(acetic acid)-thiourea (XX) which was converted to the methyl ester (XXII) by concentrated sulfuric acid/methanol and to the cyclic 1-(4-toluenesulfonyl)imidazolin-5-one-2-thione (XXI) by sulfuric acid alone.     

Magnetocaloric properties of amorphous GdNiAl obtained by mechanical grinding

An amorphous GdNiAl sample was prepared by mechanical grinding performed on a crystallised intermetallic. The treatment changes greatly the ferromagnetic behaviour of this compound; its Curie temperature decreases from 57 K (unmilled sample) to 29 K (milled sample). Specific heat and magnetisation measurements reveal that amorphous GdNiAl exhibits an interesting magnetocaloric effect; for an applied magnetic field of 5 T a change of 8.9 J/kgK is observed at 36 K for the isothermal magnetic entropy. PACS 75.30.Sg; 65.40.+g; 75.50.Kj     

Magnetic and electrical properties of the equiatomic cerium germanides CeMGe (M = Rh, Ir, Pd, Pt)

From X-ray Guinier powder data the crystal structures of the ternary germanides Ce(Rh or Ir)Ge and Ce(Pd or Pt)Ge were confirmed to be of the TiNiSi-type and the CeCu₂-type, respectively. Magnetic, electrical and thermodynamic properties of these materials have been studied in the temperature range 1.5 K T 300 K. CeRhGe orders antiferromagnetically below 9.3 K, whereas in CeIrGe cerium is in an intermediate valence state and no magnetic transition is observed down to 1.5 K. Resistivity and specific heat measurements reveal a magnetic transition near 3.4 K for both CePdGe and CePtGe. According to the present investigations the compounds CeMGe, with M = Rh, Pd, Pt are classified as magnetically ordered Kondo systems.