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State Structure (state + structure)
Kinds of State Structure Selected AbstractsOrganizational Learning and Productivity: State Structure and Foreign Investment in the Rise of the Chinese CorporationMANAGEMENT AND ORGANIZATION REVIEW, Issue 2 2005Doug Guthrie abstract Over the two and a half decades of economic reform in China, two types of Chinese firms have consistently outperformed their peers. In the 1980s, it was the firms at the lower levels of the industrial hierarchy, the township and village enterprises that were closely monitored by local governments. In the 1990s and beyond, the top performers have been those Chinese firms that have formal relationships with foreign investors. While many studies on the economic reforms in China have focused on the hardening of budget constraints and the transfer of technology from foreign to Chinese firms, I focus here on the stability created by relationships with local government offices and with powerful foreign investors. Where advocates of shock therapy have argued that a rapid transition to market institutions was the best path to building a market economy, I argue that the successful practices of the market are learned gradually over time, and the Chinese firms that are stabilized by attention from local government offices and relationships with foreign investors are well-positioned to successfully navigate China's emerging markets. A quantitative analysis of 81 firms in industrial Shanghai and three case studies help illuminate the mechanisms behind these relationships. [source] ChemInform Abstract: Oxa Bowls: Synthesis and C,H×××O Mediated Solid State Structure of Pentaoxa-[5]-peristylane.CHEMINFORM, Issue 8 2002Goverdhan Mehta Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Phase Formation and Solid State Structure on Calcination of a Nickel Ferrite Acetate Precursor.CHEMINFORM, Issue 2 2001H. Heegn Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Use of Molecular Scaffolding for the Stabilization of an Intramolecular Dative PIII -PV SystemEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 2 2003Petr Kilian Abstract The reaction of NapP2S4 (1; Nap = naphthalene-1,8-diyl) with chlorine gas gave [Nap(PCl2)(PCl4)] (2), displaying a rare ,4P-,6P bonding interaction. An X-ray structure analysis confirmed the PCl5 -like, P,P bond containing phosphonium-phosphoride structure of 2 in the crystal, which was also found in solution at low temperature. At ambient and higher temperatures, dynamic behaviour on the NMR time-scale was observed, which was assigned to interchange of the ionic phosphonium-phosphoride form 2 and the molecular bis(phosphorane) Nap(PCl3)2 form 3, rather than to the ionic phosphonium salt-phosphorane form [Nap(PCl3)(PCl2)][Cl] 4. Electronic structure calculations were performed at the B3LYP/6,31G(d,p) level of theory on structures 2 and 3; structure 3 was located as a local minimum on the potential energy surface, 15 kcal·mol,1 higher in energy than structure 2. The crystal structure and calculated P,P distances are 2.34 and 2.31 Ĺ for 2 and 3, respectively. An activation energy of 19.7 kcal·mol,1 was found for the transition state structure by coordinate driving calculations; the line-shape analysis of variable temperature 31P{1H} NMR spectra gave an activation energy of 14.4 kcal·mol,1. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Synthesis and characterization of diphenylmethyltin(IV) mono-, di-, and trichloroacetateHETEROATOM CHEMISTRY, Issue 1 2003Mostafa Mohammadpour Amini Diphenylmethyltin(IV) mono-, di-, and trichloroacetate have been synthesized and characterized by infrared, 1H, 13C, 119Sn NMR, and mass spectroscopy. Infrared spectroscopy indicates that the prepared organotin carboxylates possess chain polymer structures. NMR data show that the mono- and dichloro derivatives do not retain the solid state structure in solution. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:18,22, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10059 [source] High-level synthesis by dynamic antINTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 1-2 2004Rachaporn Keinprasit In this article, a new algorithm called dynamic ant is introduced. It was a combination of ant colony optimization (ACO) techniques and the dynamic niche sharing scheme. The interesting point of this algorithm is that it is implemented easily and could be well matched with existing design algorithms by adding the heuristic weights to speed up the algorithm. The algorithm uses the problem state structure as in the reinforcement-learning algorithm, but the storage explosion is prevented by means of the pheromone trail. This algorithm was investigated for the data path design problem of high-level synthesis of which has a large number of design steps and design techniques. © 2004 Wiley Periodicals, Inc. [source] Ab initio and DFT calculations of benzaldoxime elimination kinetics in the gas phaseINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 10 2008Jose R. Mora Abstract The mechanism for the gas-phase molecular elimination kinetics of benzaldoxime was examined at MP2/6-31G, MP2/6-31G(d,p), B3LYP/6-31G, B3LYP/6-31G(d,p), MPW1PW91/6-31G, and MPW1PW91/6-31G(d,p) levels of theory. The products of elimination of this oxime are benzonitrile and water. Calculated thermodynamic and kinetic parameters estimated from B3LYP/6-31G was found to be in better agreement with the experimental values. Transition state structure is best described as a four-membered cyclic structure with good approximation to planarity. NBO charges analysis revealed a little greater polarization of the benzylic C,H,+ rather than N,OH,,. Bond indexes and synchronicity parameters are in agreement with a concerted semi-polar type of mechanism with benzylic CH bond breaking as determining step of the reaction. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008 [source] Solid state structure and mechanical properties of melt mixed poly(trimethylene terephthalate)/polycarbonate blendsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008I. González Abstract Poly(trimethylene terephthalate) (PTT)/poly (carbonate of bisphenol A) (PC) blends were obtained in the melt state by direct injection molding and also by extrusion followed by injection molding. The blends rich in PTT were monophasic, while the blends rich in PC were biphasic with the two components of the blends present in both phases. Both the monophasic and biphasic blends were partially miscibilized, and also partially reacted, as observed by FTIR. The extent of the reaction was greater in previously mixed blends. The observed synergism in the modulus of elasticity was attributed to the increased orientation of the blend components upon blending. Although decreases in elongation at break were observed and attributed to degradation of PTT, the blends were clearly ductile and compatible. This was a consequence of either their monophasic structure, or of the presence of the two components in the two phases of the blends. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] A comprehensive theoretical study on the hydrolysis of carbonyl sulfide in the neutral waterJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 3 2008Chao Deng Abstract The detailed hydration mechanism of carbonyl sulfide (COS) in the presence of up to five water molecules has been investigated at the level of HF and MP2 with the basis set of 6-311++G(d, p). The nucleophilic addition of water molecule occurs in a concerted way across the CS bond of COS rather than across the CO bond. This preferential reaction mechanism could be rationalized in terms of Fukui functions for the both nucleophilic and electrophilic attacks. The activation barriers, ,H, for the rate-determining steps of one up to five-water hydrolyses of COS across the CS bond are 199.4, 144.4, 123.0, 115.5, and 107.9 kJ/mol in the gas phase, respectively. The most favorable hydrolysis path of COS involves a sort of eight-membered ring transition structure and other two water molecules near to the nonreactive oxygen atom but not involved in the proton transfer, suggesting that the hydrolysis of COS can be significantly mediated by the water molecule(s) and the cooperative effects of the water molecule(s) in the nonreactive region. The catalytic effect of water molecule(s) due to the alleviation of ring strain in the proton transfer process may result from the synergistic effects of rehybridization and charge reorganization from the precoordination complex to the rate-determining transition state structure induced by water molecule. The studies on the effect of temperature on the hydrolysis of COS show that the higher temperature is unfavorable for the hydrolysis of COS. PCM solvation models almost do not modify the calculated energy barriers in a significant way. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2008 [source] First-principle studies of intermolecular and intramolecular catalysis of protonated cocaineJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 10 2005Chang-Guo Zhan Abstract We have performed a series of first-principles electronic structure calculations to examine the reaction pathways and the corresponding free energy barriers for the ester hydrolysis of protonated cocaine in its chair and boat conformations. The calculated free energy barriers for the benzoyl ester hydrolysis of protonated chair cocaine are close to the corresponding barriers calculated for the benzoyl ester hydrolysis of neutral cocaine. However, the free energy barrier calculated for the methyl ester hydrolysis of protonated cocaine in its chair conformation is significantly lower than for the methyl ester hydrolysis of neutral cocaine and for the dominant pathway of the benzoyl ester hydrolysis of protonated cocaine. The significant decrease of the free energy barrier, ,4 kcal/mol, is attributed to the intramolecular acid catalysis of the methyl ester hydrolysis of protonated cocaine, because the transition state structure is stabilized by the strong hydrogen bond between the carbonyl oxygen of the methyl ester moiety and the protonated tropane N. The relative magnitudes of the free energy barriers calculated for different pathways of the ester hydrolysis of protonated chair cocaine are consistent with the experimental kinetic data for cocaine hydrolysis under physiologic conditions. Similar intramolecular acid catalysis also occurs for the benzoyl ester hydrolysis of (protonated) boat cocaine in the physiologic condition, although the contribution of the intramolecular hydrogen bonding to transition state stabilization is negligible. Nonetheless, the predictability of the intramolecular hydrogen bonding could be useful in generating antibody-based catalysts that recruit cocaine to the boat conformation and an analog that elicited antibodies to approximate the protonated tropane N and the benzoyl O more closely than the natural boat conformer might increase the contribution from hydrogen bonding. Such a stable analog of the transition state for intramolecular catalysis of cocaine benzoyl-ester hydrolysis was synthesized and used to successfully elicit a number of anticocaine catalytic antibodies. © 2005 Wiley Periodicals, Inc. J Comput Chem 26: 980,986, 2005 [source] A computational study of conformational interconversions in 1,4-dithiacyclohexane (1,4-dithiane)JOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 8 2003Fillmore Freeman Abstract Ab initio molecular orbital theory with the 6-31G(d), 6-31G(d,p), 6-31+G(d), 6-31+G(d,p), 6-31+G(2d,p), 6-311G(d), 6-311G(d,p), and 6-311+G(2d,p) basis sets and density functional theory (BLYP, B3LYP, B3P86, B3PW91) have been used to locate transition states involved in the conformational interconversions of 1,4-dithiacyclohexane (1,4-dithiane) and to calculate the geometry optimized structures, relative energies, enthalpies, entropies, and free energies of the chair and twist conformers. In the chair and 1,4-twist conformers the CHax and CHeq bond lengths are equal at each carbon, which suggest an absence of stereoelectronic hyperconjugative interactions involving carbon,hydrogen bonds. The 1,4-boat transition state structure was 9.53 to 10.5 kcal/mol higher in energy than the chair conformer and 4.75 to 5.82 kcal/mol higher in energy than the 1,4-twist conformer. Intrinsic reaction coordinate (IRC) calculations showed that the 1,4-boat transition state structure was the energy maximum in the interconversion of the enantiomers of the 1,4-twist conformer. The energy difference between the chair conformer and the 1,4-twist conformer was 4.85 kcal/mol and the chair-1,4-twist free energy difference (,G°c-t) was 4.93 kcal/mol at 298.15 K. Intrinsic reaction coordinate (IRC) calculations connected the transition state between the chair conformer and the 1,4-twist conformer. This transition state is 11.7 kcal/mol higher in energy than the chair conformer. The effects of basis sets on the 1,4-dithiane calculations and the relative energies of saturated and unsaturated six-membered dithianes and dioxanes are also discussed. © 2003 Wiley Periodicals, Inc. J Comput Chem 24: 909,919, 2003 [source] Synthesis, properties and solid state structure of 5-diphenylphosphino-2-hydroxy-1,3-xylyl-18-crown-5JOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 4 2006Rex A. Corbin 5-Diphenylphosphino-2-hydroxy-1,3-xylyl-18-crown-5 has been synthesized from 5-bromo-2-hydroxy-18-crown-5 by reacting it in sequence at low temperature with n -butyl lithium and methyl diphenylphosphonite. The phosphorous donor properties of this phenol phosphine (OH derivative) and the corresponding phenoxide (O, derivative) have been studied in the presence and absence of alkali metal ions by determining the frequencies of the A1 ,(CO) bands of Ni(CO)3L complexes. For the OH and O, derivatives, the latter generated by addition of CsOH to the former, the ,(CO) bands are observed at 2067.6 and 2063.4 cm,1, respectively, providing the trend predicted by Hammett parameters for OH and O, substituents. Addition of Na+ or K+ to the OH derivative has little effect on this stretching frequency, but the former ion shifts the O, derivative band to 2067.7 cm,1 A solid state structure has been obtained of the OH derivative, and two independent molecules were found in the unit cell. Both have a single water molecule hydrogen bonded to two across-ring oxygen atoms and the phenol hydrogen. The crown ether ring has the usual gauche and anti arrangements for the C-C and CO bonds. [source] Evidence of partial unfolding of proteins at the ice/freeze-concentrate interface by infrared microscopyJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 9 2009J. Jeff Schwegman Abstract The goal of this research was to use infrared spectroscopy in combination with a freeze drying stage to gain a better understanding of the mechanism of loss of protein integrity due to the stresses associated with freezing. Infrared spectra were collected in triplicate for the interstitial space between ice crystals and through ice crystals in a partially frozen system. Spectra were collected for lactate dehydrogenase (LDH) and human immune globulin (IgG) both in the presence and absence of an added surfactant (polysorbate 80). Spectra collected in the interstitial space, distant from the surface of ice crystals, were very similar to spectra collected from the initial solution regardless of the presence of a surfactant. Spectra collected through ice crystals, without added surfactant, were significantly different than spectra collected from the initial solution. An increase in bands characteristic of intermolecular ,-sheet structures (main component of aggregates) were present in these spectra. The presence of surfactant in both protein formulations resulted in a decrease in intermolecular ,-sheet signals in spectra of the proteins on the ice crystal surface. Additionally, much of the native state structure of LDH initially lost on the surface of ice crystals returned when surfactant was added to the formulation prior to freezing. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:3239,3246, 2009 [source] Solid-state bilayer formation from a dialkyl-substituted lariat ether that forms stable vesicles in aqueous suspensionJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 7 2001Stephen L. De Wall Abstract Previously established aggregate formation by alkyl-substituted crown ethers is considered with respect to the solid state structure of N,N,-didodecyldiaza-18-crown-6 (7), which was determined as its NaI complex (7,NaI,H2O). The complex forms a bilayer structure that was used as a benchmark for understanding the formation of aggregates and their inclusion volumes. Copyright © 2001 John Wiley & Sons, Ltd. [source] Amino acid interaction preferences in proteinsPROTEIN SCIENCE, Issue 3 2010Anupam Nath Jha Abstract Understanding the key factors that influence the interaction preferences of amino acids in the folding of proteins have remained a challenge. Here we present a knowledge-based approach for determining the effective interactions between amino acids based on amino acid type, their secondary structure, and the contact based environment that they find themselves in the native state structure as measured by their number of neighbors. We find that the optimal information is approximately encoded in a 60 × 60 matrix describing the 20 types of amino acids in three distinct secondary structures (helix, beta strand, and loop). We carry out a clustering scheme to understand the similarity between these interactions and to elucidate a nonredundant set. We demonstrate that the inferred energy parameters can be used for assessing the fit of a given sequence into a putative native state structure. [source] Mass spectrometric characterization of 4-oxopentanoic acid and gas-phase ion fragmentation mechanisms studied using a triple quadrupole and time-of-flight analyzer hybrid system and density functional theoryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 14 2008Basem Kanawati 4-Oxopentanoic acid was characterized experimentally by electrospray ionization using a triple quadrupole and time-of-flight analyzer hybrid system. This compound was chosen as a model substance for small organic compounds bearing an acetyl and a carboxyl group. Collision-induced dissociation experiments at different activation energies were performed to elucidate possible fragmentation pathways. These pathways were also studied on the theoretical level using density functional theory (DFT) B3LYP/6-311++G(3df,3pd)//B3LYP/6-31+G(d)+ZPVE calculations. CO2 ejection from the [M,H], anion of 4-oxopentanoic acid was observed and the fragmentation pathway studied by DFT reveals a new concerted mechanism for CO2 elimination accompanied by an intramolecular proton transfer within a pentagonal transition state structure. Successive elimination of water and CO from the [M,H], anion of 4-oxopentanoic acid was also observed. A rearrangement in the primary deprotonated ketene anion produced after water elimination was found on the theoretical level and leads to CO elimination from the primary product anion [M,H,H2O],. Energy diagrams along the reaction coordinates of the fragmentation pathways are presented and discussed in detail. Mulliken charge distributions of some important structures are presented. Copyright © 2008 John Wiley & Sons, Ltd. [source] Reordering Society: Vigilantism and Expressions of Sovereignty in Port Elizabeth's TownshipsDEVELOPMENT AND CHANGE, Issue 4 2006Lars Buur ABSTRACT Crime and vigilantism in South Africa are generally seen as a reaction to the breakdown of formal law. Both are constituted outside the state and emerge when the new social contract has been broken , that is, when the state can no longer provide security. This article argues that there is often an intimate relationship between vigilante formations and state structures. It explores this apparent paradox through public discourses on crime and the emergence of twilight institutions such as vigilante groups. It suggests that vigilantism has to be analysed as an attempt to promulgate a new legal-political order, despite being constructed outside this order. This argument is explored in the context of the Amadlozi, a vigilante group operating in the townships of Port Elizabeth. The article situates this discussion within an examination of discourses on crime, as well as the production of township residents and their protection from crime. Finally, it proffers some ideas on sovereignty and its relationship to twilight institutions. [source] Optimization of strong and weak coordinatesINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 12 2006Marcel Swart Abstract We present a new scheme for the geometry optimization of equilibrium and transition state structures that can be used for both strong and weak coordinates. We use a screening function that depends on atom-pair distances to differentiate strong coordinates from weak coordinates. This differentiation significantly accelerates the optimization of these coordinates, and thus of the overall geometry. An adapted version of the delocalized coordinates setup is used to generate automatically a set of internal coordinates that is shown to perform well for the geometry optimization of systems with weak and strong coordinates. For the Baker test set of 30 molecules, we need only 173 geometry cycles with PW91/TZ2P calculations, which compares well with the best previous attempts reported in literature. For the localization of transition state structures, we generate the initial Hessian matrix, using appropriate force constants from a database. In this way, one avoids the explicit computation of the Hessian matrix. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 [source] DFT study and NBO analysis of the mutual interconversion of cumulene compoundsJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 5 2007Davood Nori-Shargh Abstract The B3LYP/6-31G* method was used to investigate the configurational properties of allene (1,2-propadiene) (1), 1,2,3-butatriene (2), 1,2,3,4-pentateriene (3), 1,2,3,4,5-hexapentaene (4), 1,2,3,4,5,6-heptahexaene (5), 1,2,3,4,5,6,7-octaheptaene (6), 1,2,3,4,5,6,7,8-nonaoctaene (7), and 1,2,3,4,5,6,7,8,9-decanonaene (9). The calculations at the B3LYP/6-31G* level of theory showed that the mutual interconversion energy barrier in compounds 1,8 are: 209.73, 131.77, 120.34, 85.00, 80.91, 62.19, 55.56, and 46.83,kJ,mol,1, respectively. The results showed that the difference between the average CC double bond lengths () values in cumulene compounds 1 and 2, is larger than those between 7 and 8, which suggest that with large n (number of carbon atoms in cumulene chain), the values approach a limiting value. Accordingly, based on the plotted data, the extrapolation to n,=,,, gives nearly the same limiting (i. e., ). Also, NBO results revealed that the sum of , -bond occupancies, , decrease from 1 to 8, and inversely, the sum of , -antibonding orbital occupancies, , increase from compound 1 to compound 8. The decrease of values for compounds 1,8, is found to follow the same trend as the barrier heights of mutual interconversion in compounds 1,8, while the decrease of the barrier height of mutual interconversion in compounds 1,8 is found to follow the opposite trend as the increase in the number of carbon atom. Accordingly, besides the previously reported allylic resonant stabilization effect in the transition state structures, the results reveal that the values, , ,(EHOMO,,,ELUMO), and the C atom number could be considered as significant criteria for the mutual interconversion in cumulene compounds 1,8. This work reports also useful predictive linear relationships between mutual interconversion energy barriers () in cumulene compounds and the following four parameters: , , ,(EHOMO,,,ELUMO), and CNumber. Copyright © 2007 John Wiley & Sons, Ltd. [source] The Judicial Transformation of the State: The Case of U.S. Trade Policy, 1974,2004LAW & POLICY, Issue 1 2009NITSAN CHOREV The recent shift in state policies from Keynesianism to neoliberalism was accompanied by a transformation in state structures. The case of trade liberalization in the United States reveals that this structural transformation is of a judicial nature. In 1974, supporters of free trade successfully shifted authority over the management of protectionist claims from Congress to quasi-judicial bodies in the U.S. executive; in 1994, they successfully strengthened the dispute settlement mechanisms of the World Trade Organization. This judicial transformation indicates a shift from sites where decisions are made by way of political negotiations to sites where judges preside over legal disputes. In the article, I identify the political origins of these judicial transformations and discuss the factors that make judicial sites more favorable to neoliberal policies than political sites. [source] Computational chemistry study of the environmentally important acid-catalyzed hydrolysis of atrazine and related 2-chloro- s -triazinesPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 8 2002Phillip Sawunyama Abstract Many chlorine-containing pesticides, for example 2-chloro- s -triazines, are of great concern both environmentally and toxicologically. As a result, ascertaining or predicting the fate and transport of these compounds in soils and water is of current interest. Transformation pathways for 2-chloro- s -triazines in the environment include dealkylation, dechlorination (hydrolysis), and ring cleavage. This study explored the feasibility of using computational chemistry, specifically the hybrid density functional theory method, B3LYP, to predict hydrolysis trends of atrazine (2-chloro- N4 -ethyl- N6 -isopropyl-1,3,5-triazine-2,4-diamine) and related 2-chloro- s -triazines to the corresponding 2-hydroxy- s -triazines. Gas-phase energetics are described on the basis of calculations performed at the B3LYP/6-311++G(d,p)//B3LYP/6-31G* level of theory. Calculated free energies of hydrolysis (,hG298) are nearly the same for simazine (2-chloro- N4,N6 -diethyl-1,3,5-triazine-2,4-diamine), atrazine, and propazine (2-chloro- N4,N6 -di-isopropyl-1,3,5-triazine-2,4-diamine), suggesting that hydrolysis is not significantly affected by the side-chain amine-nitrogen alkyl substituents. High-energy barriers also suggest that the reactions are not likely to be observed in the gas phase. Aqueous solvation effects were examined by means of self-consistent reaction field methods (SCRF). Molecular structures were optimized at the B3LYP/6-31G* level using the Onsager model, and solvation energies were calculated at the B3LYP/6-311++G(d,p) level using the isodensity surface polarizable continuum model (IPCM). Although the extent of solvent stabilization was greater for cationic species than neutral ones, the full extent of solvation is underestimated, especially for the transition state structures. As a consequence, the calculated hydrolysis barrier for protonated atrazine is exaggerated compared with the experimentally determined one. Overall, the hydrolysis reactions follow a concerted nucleophilic aromatic substitution (SNAr) pathway. Published in 2002 for SCI by John Wiley & Sons, Ltd [source] The X-ray structure determination of bovine carbonmonoxy hemoglobin at 2.1 Ĺ resoultion and its relationship to the quaternary structures of other hemoglobin crystal formsPROTEIN SCIENCE, Issue 6 2001Martin K. Safo Abstract Crystallographic studies of the intermediate states between unliganded and fully liganded hemoglobin (Hb) have revealed a large range of subtle but functionally important structural differences. Only one T state has been reported, whereas three other quaternary states (the R state, B state, and R2 or Y state) for liganded Hb have been characterized; other studies have defined liganded Hbs that are intermediate between the T and R states. The high-salt crystal structure of bovine carbonmonoxy (CO bovine) Hb has been determined at a resolution of 2.1 Ĺ and is described here. A detailed comparison with other crystallographically solved Hb forms (T, R, R2 or Y) shows that the quaternary structure of CO bovine Hb closely resembles R state Hb. However, our analysis of these structures has identified several important differences between CO bovine Hb and R state Hb. Compared with the R state structures, the ,-subunit N-terminal region has shifted closer to the central water cavity in CO bovine Hb. In addition, both the ,- and ,-subunits in CO bovine Hb have more constrained heme environments that appear to be intermediate between the T and R states. Moreover, the distal pocket of the ,-subunit heme in CO bovine Hb shows significantly closer interaction between the bound CO ligand and the Hb distal residues Val 63(E11) and His 63(E7). The constrained heme groups and the increased steric contact involving the CO ligand and the distal heme residues relative to human Hb may explain in part the low intrinsic oxygen affinity of bovine Hb. [source] Sulfonamide bond cleavage in benzenesulfonamides and rearrangement of the resulting p -aminophenylsulfonyl cations: application to a 2-pyrimidinyloxybenzylaminobenzenesulfonamide herbicideRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 12 2005Hao-Yang Wang The gas-phase fragmentation/rearrangement reactions of compound 1, [2-(4,6-dimethoxypyrimidin-2-yloxy)-benzyl]-[4-(piperidine-1-sulfonyl)phenyl]amine, have been examined by Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS). The analyses reveal that under sustained off-resonance irradiation collision-induced dissociation (SORI-CID) conditions in the FTICR cell, protonated 1 undergoes two competitive pathways initiated by different protonation positions. The first pathway is initiated by protonation on the amino group and yields only one fragment ion due to loss of the entire benzenesulfonamide moiety. In the second pathway, protonation of the sulfonamide group leads to cleavage of a sulfonamide bond with loss of the neutral piperidine, followed by loss of SO via a sulfonyl cation rearrangement. An intramolecular SNAr mechanism is proposed to rationalize the rearrangement of the p -aminophenylsulfonyl cation and the resulting SO loss. To test the generality of this process, SORI-CID spectra of protonated sulfamethoxazole and of the p -aminophenylsulfonyl cation (SBN) were obtained. For the SBN ion, SORI-CID experiments as well as density functional theory (B3LYP) calculations show that rearrangement, assigned as a SNAr reaction of the sulfonyl cation group, can account for the observed SO loss process. Candidate transition state structures were optimized at the B3LYP/6-31+G (d, p) level of theory using the Gaussian98 molecular modeling package. The computational results show that the barrier for SO loss from SBN is much lower than that for SO2 loss, which satisfactorily rationalizes the SORI-CID experimental results for SBN. Moreover, it is proposed that a fragment ion at m/z 196 in the MS/MS spectrum of protonated 1 is formed via the ion resulting from SO loss via a second intramolecular SNAr mechanism. Copyright © 2005 John Wiley & Sons, Ltd. [source] Regulation of space in the contemporary postcolonial Pacific city: Port Moresby and SuvaASIA PACIFIC VIEWPOINT, Issue 3 2003John Connell Abstract:,National development problems in the weak states of Papua New Guinea and Fiji have resulted in external intervention. However neo-liberal development strategies have not resolved development problems and may have further weakened state structures. In both capital cities rural-urban migration, rising urban unemployment, and the expansion of squatter settlements and the informal sector have all continued in recent years. The numbers of beggars, street kids and prostitutes have increased, as has domestic violence and crime. Governments have opposed all these trends, by regulation and intolerance, violence, routine repression and eviction, rather than by pro-poor policies. Settlers, prostitutes, beggars, street kids and market vendors have been evicted and moved on, on the ideological premise that that their true place is in rural areas, and that their urban presence challenges and threatens notions of urban order. Moral regulation, social exclusion and moral panic have divided ,good citizens' from marginal and possibly criminal others, intensifying social divisions within the cities. Sustainable urban development has proved difficult to achieve. [source] | |||||||||||||||||||||||||