A note on differentiability of the cluster density for independent percolation in high dimensions

The cluster density function of independent percolation in ad-dimensional lattice is considered. For eachn, it is shown that(p) has finitenth leftderivative at critical probabilityp _c ifd is sufficiently large. This result agrees with the Bethe lattice approximation, where thenth one-sided derivative of(p) is bounded atp _c for alln.     

Inorganic reaction mechanisms. vol. 4 (A chemical society specialist report) : A. McAuley,Senior reporter,The Chemcial Society,London, 1976, xviii + 398 pages, £ 23.00, $63.25.

The palladium(I) and platinum(I) complexes [(CH₃NC)₆M₂]²⁺ undergo substitution reactions with isocyanides, phosphines and halide or pseudohalide ions. With triphenylphosphine, axial substitution is preferred. The product [(CH₃NC)₅(Ph₃P)Pd₂]²⁺ is fluxional.     

Syntheses and properties of 4-hydroxy-3,5-dibromobenzyl phosphonates and their flame-retarding effects on ABS copolymer

4-Hydroxy-3,5-dibromobenzyl phosphonates (HDBBP) were synthesized by reacting phosphites with 4-hydroxy-3,5-dibromobenzyl bromide (HDBBB) which was prepared in advance by photobromination of 2,6-dibromo-p-cresol (DBPC) produced by bromination of p-cresol. In the reactions between HDBBB and phosphites, the rate of formation of dimethyl 4-hydroxy-3,5-dibromobenzyl phosphonate (HDBBP_m) was greater than that of diphenyl 4-hydroxy-3,5-dibromobenzyl phosphonate (HDBBP_P); however, quantitative yields for both products were obtainable. The addition of HDBBP as bromine and phosphorus containing flame-retardants to ABS copolymer showed better results than the addition of the same amount of brominated compound, or mixtures of both two compounds. It was also proved that compound containing both bromine and phosphorus exhibited more apparent synergistic effects on flame retardancy than the mixtures of brominated compound and phosphorous containing compound     

Synthesis of monodisperse polymers from proteins

Proteins are functional biopolymers; viewed as molecules, they are also monodisperse polyamides with chemically reactive side chains. This paper describes the use of proteins as starting materials for the synthesis of monodisperse polymers with nonbiological functionalities attached to the side chains. It demonstrates the complete derivatization of amine groups (lysine side chains and N-termini) on three different proteins by addition of activated carboxylate reagents in aqueous solutions containing sodium dedecyl sulfate (SDS), under denaturing conditions. Several different acylating reagents were used to generate derivatized proteins; the resulting compounds constitute a new class of monodisperse, semisynthetic polymers, having the potential for wide variation in the structure of the backbone and of the side chains. Modification of lysozyme on a gram scale demonstrated that the method can generate useful quantities of material.     

Comparative studies of the photoinduced reactions in the Mg+-SCNC2H5 and Mg+-NCSC2H5 complexes

The photoinduced reactions of the complexes Mg+-SCNC2H5 and Mg+-NCSC2H5 are studied comparatively in the spectral range of 230-440 nm. One-photon excitation of the complexes through the Mg+ chromophore (3 2P <-- 3 2S) gives rise to the evaporative fragment as well as the molecular activation and charge transfer products. The action spectra of the complexes consist of three broad peaks for Mg+-SCNC2H5 and two for Mg+-NCSC2H5, which accord with the structures obtained from quantum mechanics calculations. These calculations reveal two association isomers for Mg+-SCNC2H5: one is with Mg+ being linked to the S atom and the other to the N atom. The former is more stable than the latter by only 0.23 eV. Both of the isomers have been shown to exist in the complex source employed in our experiments. On the other hand, only one stable structure is found for the complex Mg+-NCSC2H5 characterized by the Mg+-N linkage. In general, the photofragments are dominated by Mg+ at lambda > 400 nm, which decreases with decreasing wavelength accompanied by the increase in other photoproducts. In addition, the branching ratios of Mg+ to other photoproducts are nearly constant in the short wavelength region but decrease with decreasing wavelength. The observed photoreactions have been reasonably explained.     

The peptide hormone angiotensin II: its new functions in tissues and organs

The peptide hormone angiotensin II is well established to play an endocrine role in the regulation of blood pressure, fluid and electrolyte homeostasis. In addition to its hemodynamic function, recent studies have shown that numerous tissues and organs contain their own locally generated angiotensin products (angiotensin II, III, IV and Ang 1-7) and they exhibit their respective activities. Such an intrinsic angiotensin-generating system renders to specific tissue function of our body, frequently via the regulatory mechanism of a paracrine, autocrine or intracrine manner. These tissues and organs include, to name but a few, the brain, bone marrow, adipose, epididymis, carotid body, liver, and pancreas. This local system has been shown to be responsive to various stimuli of physiological and pathophysiological importance. Moreover, the locally generated angiotensin peptides have multiple and novel actions including cell growth, anti-proliferation, apoptosis, reactive oxygen species generation, hormonal secretion, pro-inflammatory, and pro-fibrogenic actions, as well as vasoconstriction and vasodilatation. Notwithstanding the emerging roles of angiotensin II in various tissues and organs, the physiological significance and ultimately the clinical relevance remain largely undefined. Future target for these new functions by making use of specific renin-angiotensin system inhibitors, such as the angiotensin-converting enzyme and angiotensin II receptor blockers either in mono-therapy or in combination, could be of clinical importance. The current review is to focus on some of the new functions arising from the locally formed angiotensin II in tissues and organs, with particular attention to its emerging roles in the liver and the pancreas.     

Catalysis by methyltrioxorhenium(VII): reduction of hydronium ions by europium(II) and reduction of perchlorate ions by europium(II) and chromium(II)

The title reactions occur stepwise, the first and fastest being MeReO3 + Eu2+ --> Re(VI) + Eu3+ (k298 = 2.7 x 10(4) L mol(-1) s(-1)), followed by rapid reduction of Re(VI) by Eu2+ to MeReO2. The latter species is reduced by a third Eu2+ to Re(IV), a metastable species characterized by an intense charge transfer band, epsilon410 = 910 L mol(-1) cm(-1) at pH 1; the rate constant for its formation is 61.3 L mol(-1) s(-1), independent of [H+]. Yet another reduction step occurs, during which hydrogen is evolved at a rate v = k[Re(IV)][Eu2+][H+](-1), with k = 2.56 s(-1) at mu = 0.33 mol L(-1). The 410 nm Re(IV) species bears no ionic charge on the basis of the kinetic salt effect. We attribute hydrogen evolution to a reaction between H-ReVO and H3O+, where the hydrido complex arises from the unimolecular rearrangement of Re(III)-OH in a reaction that cannot be detected directly. Chromium(II) ions do not evolve H2, despite E(Cr) degrees approximately E(EU) degrees. We attribute this lack of reactivity to the Re(IV) intermediate being captured as [Re(IV)-O-Cr(III)]2+, with both metals having substitutionally inert d3 electronic configurations. Hydrogen evolution occurs in chloride or triflate media; with perchlorate present, MeReO2 reduces perchlorate to chloride, as reported previously [Abu-Omar, M. M.; Espenson, J. H. Inorg. Chem. 1995, 34, 6239-6240].