Mechanical properties and transition temperatures of crosslinked-oriented gelatin

 This second part of a systematic study of the properties of crosslinked-oriented gelatin involves the effects of orientation and water content on the glass transition temperature T _g and on the melting behavior. The samples were the same as those in the preceding study, and their transition temperatures were determined by both differential scanning calorimetry and dynamic mechanical thermal analysis. The crosslinked gelatin which had been room-conditioned showed two transition temperatures: the lower one was attributed to T _g of the water-plasticized gelatin, and the higher one was interpreted as T _g of dried gelatin superimposed by melting. A rather unusual situation arose because of the fact that the T _g and melting temperatures T _m (217 and 230 ^°C, respectively) are so similar. Using water as plasticizer not only decreases T _g but produces imperfect crystallites which melt below the T _g of the system. The presence of the amorphous phase in the glassy state would presumably make it essentially impossible to define a melting point or crystallization temperature in the normal manner, as an equilibrium between crystalline and amorphous phases. Received: 8 October 1996 Accepted: 2 November 1995     

Kähler Reduction of Metrics with Holonomy G<Subscript>2</Subscript>

A torsion-free G₂ structure admitting an infinitesimal isometry such that the quotient is a Kähler manifold is shown to give rise to a 4-manifold equipped with a complex symplectic structure and a 1-parameter family of functions and 2-forms linked by second order equations. Reversing the process in various special cases leads to the construction of explicit metrics with holonomy equal to G₂.     

Determination of Cu and Ni in French geological standards AN-G,BE-N and MA-N

Using radiochemical separation, the content of Cu and Ni were determined in French geological standards AN-G (anorthosite) BE-N (basalte) and MA-N (granite). Separation was done by solvent extraction of Cu(II) and Co(III) (reaction⁵⁸Ni(n, p)⁵⁸Co) as DDC complexes in CHCl₃.     

Bihermitian Structures On Complex Surfaces

We correct the statements of Theorem 1 and Corollary 2 of theabove-mentioned paper and provide a new argument for Corollary2. We also update some parts of the paper in the light of recentmajor developments in the theory of bihermitian structures,due to M. Gualtieri and N. Hitchin. 2000 Mathematics SubjectClassification 53C26 (primary), 32J15, 53C56 (secondary).     

Symplectic 4-manifolds with Hermitian Weyl tensor

It is proved that any compact almost Kähler, Einstein 4-manifold whose fundamental form is a root of the Weyl tensor is necessarily Kähler.     

Extraction and neutron activation determination of trace amounts of indium in air

A method for tracing hot stack gases with indium and its quick analysis by extraction with HDEHP in toluene from aqueous nitric acid followed by neutron activation analysis is described.     

Bihermitian surfaces with odd first Betti number

Compact bihermitian surfaces are considered, that is, compact, oriented, conformal four-manifolds admitting two distinct compatible complex structures. It is shown that if the first Betti number is odd then, with respect to either complex structure, such a manifold belongs to Class VII of the Enriques-Kodaira classification. Moreover, it must be either a special Hopf or an Inoue surface (in the strongly bihermitian case), or obtained by blowing-up a minimal class VII surface with curves (in the non-strongly bihermitian case). Received: 10 December 1999; in final form: 29 January 2000 / Published online: 25 June 2001     

Investigation of the magnetic properties of the Fe2-xCrxCaO4 system

Conclusions Due to the fact that the iron ions in two neighbouring elementary cells along the c-axis are in symmetry positions in relation to the oxygen anion (through which the interaction with other iron ions is achieved), the stronger 120° and 130° interactions could be considered as interactions not by zigzag-formed chains, but by the folded planes with c-axis as a generant, i.e., the quasi-twodimensional magnetic properties are evinced in Cr_xFe_2–xCaO₄.