9 research outputs found
Cytogenetics of microbe-associated parthenogenesis and its consequences for gene flow in Trichogramma wasps.
Does time until mating affect progeny sex ratio ? A manipulative experiment with the parasitoid wasp Aphelinus asychis
International audienc
Egg size variation does not affect offspring performance under intraspecific competition in Nasonia vitripennis, a gregarious parasitoid
Influence of adult nutrition on the relationship between body size and reproductive parameters in a parasitoid wasp
A universal modified van der Waals equation of state. Part I: Polymer and mineral glass formers
PVT data of glass formers (minerals and polymers) published in the literature are re-analyzed. All the polymer glass formers (PS, PVAc, PVME, PMMA, POMS, PBMA, PVC, PE, PP, PMPS, PMTS, PPG) present two main properties which have never been noted: a) the isobars P(V) have a fan structure characterized by the two parameters T* and V*; b) the isotherms verify the principle of temperature-pressure superposition for P < P
*. From these properties we show that the Equation Of State (EOS) can be put on a modified van der Waals form (VW-EOS), (V − V
*) = (V0 − V
*)P
*/(P + P
*) . The characteristic pressure P* and the covolume V* are T and P independent. In polymer glass formers P* and V* have same values in the α (melt) and β (glass) domains. The characteristic temperatures T
* deduced from the Fan Structure of the Isobar (FSIb) above and below T
g
are different. The characteristic temperature T
*(α) of the melt state is found near the Vogel temperature T
0 for linear polymers and more than 100 K below T
0 for atactic polymers (with pendent groups). This difference in atactic polymers (and in some low molecular weight compounds) is explained by the importance of the β motions due to the pendent groups. The independence of T
0 on P is discussed. A modified VFT equation (analogous to the compensation law and Meyer-Neldel rule) giving the relaxation time τ of the α motions as a function of P and T is proposed. The fan structure of the isotherm logτ versus P is explained. It is shown that organic non-polymeric liquids (C6H12, C6H14, DHIQ, OTP, Glycerol, Salol, PDE, DGEBA), mineral glass (SiO2, Se, GeSe4, GeSe2, GeO2, As2O3 and two metallic glasses (LaCe and CaAl alloys) verify this VW-EOS with similar accuracy. The relation P
* = B
0/γ
B
among the characteristic pressure P
*, the zero-pressure modulus B
0 and the Slatter-Grüneisen anharmonicity parameter γ
B
deduced from the VW-EOS, is observed in all the glass formers