Hammett Correlations in the \u3csup\u3e1\u3c/sup\u3eH NMR Spectra of Some N-Arlydihalonicotinamides

Excellent linear correlations of amide proton chemical shifts (Snh) (in DMSO-d6 ) with Hammett substituent constants (5) for a series of 4-substituted anilides of four dihalonicotinic acid systems were observed. Dihalonicotinanilides with chlorine in the pyridine 2 - position exhibited a more positive slope in a Hammett plot of S^H vs - aR- where R is the substituent in the 4 position of the benzene ring. This observation is explained in terms of the inductive effect of chlorine which results in a slightly more acidic amide proton, which in turn causes an enhanced hydrogen bonding tendency to solvent. Four disubstituted anilides were also prepared, and the 5NH of these derivatives correlated well with the additive value of the 6R\u27s of the two substituents

Preparation of a Series of N-Phenylamides of 5-Bromo-6-Chloronicontinic Acid and 5-Bromo-2-Chloronicontinic Acid

A series of N-phenylamides of 5-bromo 6-chloronicotinic acid and 5-bromo-2-chloronicotinic acid were synthesized by treatment of their freshly prepared acid chlorides with the appropriately ring substituted anilines. Thirty new compounds were prepared, and their structures were ascertained by elemental analyses and spectroscopic techniques. Spectroscopic trends in the infrared spectra of the two series were examined in an attempt to correlate structural and electronic effects to hydrogen bonding tendencies

Preparation of a Series of Substituted N-Phenyl-5-Bromo-6-Chloro- and 5-Bromo-6-Chloronicotinates of Potential Agricultural Interest

Substituted phenyl esters of 5-bromo-2-chloronicotinic acid and 5 bromo 6-chloronicotinic acid were prepared. The acids were first converted to their respective acid chlorides using thionyl chloride, and the acid chlorides were immediately transformed to the esters by treatment with the appropriately substituted phenol in sodium hydroxide solution. Aunique chloride displacement of bromide was observed on attempting to convert 5,6-dibromonicotinic acid to its acid chlorid

Identification of sex hormone-binding globulin in the human hypothalamus

Gonadal steroids are known to influence hypothalamic functions through both genomic and non-genomic pathways. Sex hormone-binding globulin ( SHBG) may act by a non-genomic mechanism independent of classical steroid receptors. Here we describe the immunocytochemical mapping of SHBG-containing neurons and nerve fibers in the human hypothalamus and infundibulum. Mass spectrometry and Western blot analysis were also used to characterize the biochemical characteristics of SHBG in the hypothalamus and cerebrospinal fluid (CSF) of humans. SHBG-immunoreactive neurons were observed in the supraoptic nucleus, the suprachiasmatic nucleus, the bed nucleus of the stria terminalis, paraventricular nucleus, arcuate nucleus, the perifornical region and the medial preoptic area in human brains. There were SHBG-immunoreactive axons in the median eminence and the infundibulum. A partial colocalization with oxytocin could be observed in the posterior pituitary lobe in consecutive semithin sections. We also found strong immunoreactivity for SHBG in epithelial cells of the choroid plexus and in a portion of the ependymal cells lining the third ventricle. Mass spectrometry showed that affinity-purified SHBG from the hypothalamus and choroid plexus is structurally similar to the SHBG identified in the CSF. The multiple localizations of SHBG suggest neurohypophyseal and neuroendocrine functions. The biochemical data suggest that CSF SHBG is of brain rather than blood origin. Copyright (c) 2005 S. Karger AG, Base

Performance-based contracting in the defence industry: Exploring triadic dynamics between government, OEMs and suppliers

This study takes a rare longitudinal perspective to examine performance-based contracting (PBC) in the context of the development of a major capital defence project. It employs a triadic framework to examine changes in actors and their roles over time in fulfilling the project. The triads involve both contractors as suppliers and government entities. More specifically, using a historical narrative method the study suggests that over the 30 year span of the new warship’s development, different parties occupy the nodes of triads where the roles or functions of the principal and agents in the contract change over time. Our use of a triadic perspective enables us to trace both the withdrawal of the government customer from a position of authority and the specific strategy of one supplier to occupy the vacated role as systems integrator. The study makes three distinct contributions: firstly, to our understanding of PBC through tracing the development of the conditions that enable PBC in largescale long-term public-private contracting such as clear role delineation. Second, it adds to understanding of principal-agent behaviour in triadic public-private projects, suggesting that customer and supplier roles need to be perceived as supply network dynamics. Third, it suggests reasons why this defence acquisition underperformed, focusing on the mediation of the customer’s value requirement through powerful players seeking to extend their control. We argue PBC must be re-assessed in complex environments to include less direct financial measures such as long-term market share and adopt a more nuanced approach to contractual management than simply transferring risk.We wish to acknowledge the financial assistance provided by the Chartered Institute of Purchasing & Supply and the Institute of Supply Management

The Circumstellar Extinction of Planetary Nebulae

We analyze the dependence of circumstellar extinction on core mass for the brightest planetary nebulae (PNe) in the Magellanic Clouds and M31. We show that in all three galaxies, a statistically significant correlation exists between the two quantities, such that high core mass objects have greater extinction. We model this behavior, and show that the relation is a simple consequence of the greater mass loss and faster evolution times of high mass stars. The relation is important because it provides a natural explanation for the invariance of the [O III] 5007 planetary nebula luminosity function (PNLF) with population age: bright Population I PNe are extinguished below the cutoff of the PNLF. It also explains the counter-intuitive observation that intrinsically luminous Population I PNe often appear fainter than PNe from older, low-mass progenitors.Comment: 12 pages, 2 figures, accepted for ApJ, April 10, 199

Four new black hole candidates identified in M31 globular clusters with Chandra and XMM-Newton

We have identified four new black hole candidates in M31 globular clusters using 123 Chandra, and 4 XMM-Newton observations of the M31 central region. The X-ray source associated with Bo 163 (XB163) is a recurrent transient, with the highest luminosity ~1.4E+38 erg/s, considerably brighter than any outbursts from the neutron star transients Aql X-1 or 4U 1608-452; the outburst apparently started ~45 days earlier than the observed peak, hence the luminosity could have been considerably higher. We identified XB082, XB153 and XB185 as BHCs by observing "low state" emission spectra at luminosities that exceed the threshold for neutron star binaries. The probability that these are neutron star systems with anisotropic emission beamed toward us is <4E-4, and their variability suggests emission from a single source. We therefore conclude that these systems likely contain black holes rather than neutron stars. We have now identified 4 persistently bright BHCs in the region; the probability that these are all background AGN is <1E-20. According to theory, the donors could be tidally captured main sequence stars, or white dwarves in ultra-compact binaries. We find that GCs that are particularly massive (XB082) or metal rich (XB144) can host bright X-ray sources in addition to those that are both (XB163). Our method may reveal BHCs in other bright X-ray sources.Comment: Accepted for publication in ApJ. 17 pages, 5 figure

Some FRW Models of Accelerating Universe with Dark Energy

The paper deals with a spatially homogeneous and isotropic FRW space-time filled with perfect fluid and dark energy components. The two sources are assumed to interact minimally, and therefore their energy momentum tensors are conserved separately. A special law of variation for the Hubble parameter proposed by Berman (1983) has been utilized to solve the field equations. The Berman's law yields two explicit forms of the scale factor governing the FRW space-time and constant values of deceleration parameter. The role of dark energy with variable equation of state parameter has been studied in detail in the evolution of FRW universe. It has been found that dark energy dominates the universe at the present epoch, which is consistent with the observations. The physical behavior of the universe is discussed in detail.Comment: 10 pages, 5 figure