Low-x evolution equations in M?bius representation

The M?bius form of the BFKL kernel in the next-to-leading order (NLO) in theories containing fermions and scalars in arbitrary representations of the colour group is presented. The ambiguity of the NLO kernels permits to get agreement between the BFKL approach and the colour dipole model and to find the quasi-conformal representation of the BFKL kernel.     

C2C12 myoblast sensitivity to different apoptotic chemical triggers

Apoptosis is a form of cell death crucial for normal development and tissue homeostasis. Its typical features include chromatin changes, nuclear breakdown, plasma membrane blebbing and splitting of cellular content into apoptotic bodies, that progressively undergo phagocytosis.Apoptosis is considered essential for skeletal muscle development, where defective cells are deleted during differentiation. In addition, it plays a relevant role in several muscle myopathies, as well as in denervation and disuse.The aim of this study was to evaluate muscle cell sensitivity to different apoptotic triggers, acting through different mechanisms of action. Chemical agents, active against distinct intracellular targets, such as mitochondrial respiratory chain and DNA, have been chosen to better highlight cell death mechanisms. To induce apoptosis, C2C12 myoblasts have been exposed to H₂O₂, staurosporine, cisplatin and etoposide, at different doses and incubation times, and they have been analysed by flow cytometry, scanning and transmission electron microscopy.Flow cytometry analysis revealed a certain subdiploid peak after all treatments. The best apoptotic effect was observable, as confirmed at reverted microscope, at minimum doses and after the major exposure time.At ultrastructural level programmed cell death has been observed. Characteristic chromatin condensation and margination, as well as apoptotic bodies, frequently appeared, even if in the presence of secondary necrosis; surface blebs were also observed during scanning microscopic observation.In particular, exposure to H₂O₂ or staurosporine showed the largest number of myoblasts in late apoptotic stages and in secondary necrosis. Cisplatin treatments revealed few early apoptotic cells. The analysis of etoposide-induced apoptosis was in agreement with data obtained from flow cytometry, indicating a significant increase of apoptotic cell number.These results suggest that all conditions are able to induce apoptosis in C2C12 myoblasts, which occurs, considering trigger mechanisms of action, mostly following the mitochondrial pathway, if not excluding that due to DNA damage. Therefore, mitochondria permeability alteration is an important step in skeletal muscle programmed cell death. This last conclusion seems to have a significant relevance in understanding the mechanisms involved in muscle disorders, denervation and chronic muscle disuse, conditions frequently characterized by a decline in mitochondrial content and by an increase of mitochondrial apoptosis susceptibility.     

Analysis of polybrominated diphenyl ethers in atmospheric deposition and snow samples by solid-phase disk extraction

An extraction method for the quantitative analysis of polybrominated diphenyl ethers (PBDEs) in aqueous samples has been evaluated. The analytical methodology includes the sample filtration through glass fiber filter and subsequent extraction of dissolved phase compounds by C18 solid-phase disk extraction. Dependence of extraction efficiency on factors such as pollutant concentrations, sample volume, and stability during storage has been investigated. Mean extraction efficiencies of 97% for total PBDEs (13 tri- to heptabrominated congeners at spiking levels in the range of 15-90pg) with a RSD between 9 and 20% were achieved. Higher recoveries were observed for the more volatile PBDEs (112%) in relation to more brominated congeners (88%). The developed methodology was successfully applied to the analysis of these compounds in atmospheric deposition and snow samples from remote sites in Europe with method detection and quantitation limits in the range of 2.1-10pgL(-1) for almost all congeners, which allow the determination of PBDEs in remote areas with levels in the range of low to medium pgL(-1) for SigmaPBDEs.     

Template effects in the formation of [2]pseudo-rotaxanes containing diazapyrenium units

The template effects exerted by guests 14 and 15 in the ring closure reaction of 3 have been quantitatively evaluated. The rate largely increases in the presence of the two templates. The results are compared with those relative to the ring closure reaction of 1 yielding cyclobis(paraquat-p-phenylene), 2. The comparison indicates that the formation of tetracationic aromatic cycles templated by aromatic donors benefits from the use of extended pi surfaces both in the acceptor and in the donor components.     

Pre-equilibrium γ ray emission in different reaction mechanisms at 8 MeV/nucleon

Recent experimental results on particles-γ coincidence measurements on the systems ¹²C +⁶⁴Ni and ³⁵Cl +⁶⁴Ni at about 8 MeV/nucleon are interpreted as due to the effect of a Dipole pre-equilibrium emission produced during the damping of the proton-neutron relative collective motion in very deformed intermediate systems formed in the first instants of the collision. The pre-equilibrium effects are evaluated through semiclassic kinetic theories and through modified statistical approach to include non-stationary effects in Fusion processes, Massive Transfer reactions (in the ¹²C +⁶⁴Ni system) and in Binary Dissipative reactions (in the ³⁵Cl +⁶⁴Ni system). In particular the study performed on the dipole molecular component allows to establish a link between the above phenomenon and the charge and mass transfer process in quasi-peripheral reactions. Received: 15 April 1998 / Revised version: 8 June 1998     

Analytic continuation in two-color QCD: new results on the critical line

We test the method of analytic continuation from imaginary to real chemical potential in two-color QCD, which is free from the sign problem. In particular, we consider the analytic continuation of the critical line to real values of the chemical potential.     

Gold(I) and silver(I) mixed-metal trinuclear complexes: dimeric products from the reaction of gold(I) carbeniates or benzylimidazolates with silver(I) 3,5-diphenylpyrazolate

Trinuclear mixed-metal gold-silver compounds are obtained by the reaction of gold(I) carbeniate [Au(mu-C(OEt)=NC6H4-p-CH3)]3, TR(carb), or gold(I) imidazolate [Au-mu-C,N-1-benzyl-2-imidazolate]3, TR(bzim), with silver(I) pyrazolate [Ag(mu-3,5-Ph2pz)]3. The crystalline products are mixed-ligand, mixed-metal dimeric products [Au(carb)Ag2(mu-3,5-Ph2pz)2], [Au2(carb)2Ag(mu-3,5-Ph2pz)].CH2Cl2, [Au(bzim)2Ag2(mu-3,5-Ph2pz)], and [Au2(bzim)2Ag(mu-3,5-Ph2pz)]. They have been characterized by elemental analysis and 1H NMR and mass spectrometry. The X-ray structure of [Au(carb)Ag2(mu-3,5-Ph2pz)2] shows it to be a dimer with two Ag...Au contacts between the trinuclear units of 3.083(2) and 3.310(2) A and with average intramolecular Ag...Ag and Au...Ag distances of approximately 3.3 and 3.2 A, respectively. The structure of [Au2(carb)2Ag(mu-3,5-Ph2pz)].CH2Cl2 is a dimer with one intermolecular Au...Au attraction of 3.3354(10) A and a short Ag...Au distance of approximately 3.42 A and intramolecular Ag...Au and Au...Au contacts of approximately 3.2 and approximately 3.3 A, respectively. Packing diagrams of both complexes show that the dimeric units are independent, similar to their parent molecules. The dimers of trinuclear [Au(carb)Ag2(mu-3,5-Ph2pz)2] and [Au2(carb)2Ag(mu-3,5-Ph2pz)].CH2Cl2 crystallize in the triclinic space group P (Z = 2), a = 9.688(3) A, b = 15.542(4) A, c = 23.689(6) A, alpha = 82.560(5) degrees , beta = 87.887(6) degrees , gamma = 78.060(5) degrees , and the orthorhombic space group Pca2(1) (Z = 4), a = 29.644(4) A, b = 7.4582(10) A, c = 30.473(4) A, respectively. The structure of [Au(bzim)Ag2(mu-3,5-Ph2pz)2] is a dimer with two metallophilic Ag...Au interactions of 3.14 A. The complex crystallizes in the monoclinic space group C2/c (Z = 4), a = 26.368(5) A, b = 15.672(3) A, c = 17.010(3) A, beta = 102.206(3) degrees .