NusG is required to overcome a kinetic limitation to Rho function at an intragenic terminator.

Rho-dependent transcription termination at certain terminators in Escherichia coli also depends on the presence of NusG [Sullivan, S. L. & Gottesman, M. E. (1992) Cell 68, 989-994]. We have found that termination at the first intragenic terminator in lacZ (tiZ1) is strongly dependent on NusG when transcription is done in vitro with the concentrations of NTPs found in vivo. With a lower level of NTPs, and consequently a slower rate of RNA-chain growth, Rho causes some termination by itself that is enhanced with NusG. These results suggest that NusG serves to overcome a kinetic limitation of Rho to function at certain terminators. At a second intragenic terminator within the lacZ reading frame (tiZ2) the efficiency of Rho-mediated termination was unaffected by either NusG or by RNA polymerase elongation kinetics. Thus, using purified components and intracellular levels of NTPs, we have confirmed the in vivo finding that certain Rho-dependent terminators also depend on NusG, whereas others do not.

Basis for selection of improved carbohydrate-binding single-chain antibodies from synthetic gene libraries.

A technique is described for the simultaneous and controlled random mutation of all three heavy or light chain complementarity-determining regions (CDRs) in a single-chain Fv specific for the O polysaccharide of Salmonella serogroup B. Sense oligonucleotides were synthesized such that the central bases encoding a CDR were randomized by equimolar spiking with A, G, C, and T at a level of 10% while the antisense strands contained inosine in the spiked regions. Phage display of libraries assembled from the spiked oligonucleotides by a synthetic ligase chain reaction demonstrated a bias for selection of mutants that formed dimers and higher oligomers. Kinetic analyses showed that oligomerization increased association rates in addition to slowing dissociation rates. In combination with some contribution from reduced steric clashes with residues in heavy-chain CDR2, oligomerization resulted in functional affinities that were much higher than that of the monomeric form of the wild-type single-chain Fv.

Modeling the molecular weight distribution of block copolymer formation in a reversible addition-fragmentation chain transfer mediated living radical polymerization

Block copolymers have become an integral part of the preparation of complex architectures through self-assembly. The use of reversible addition-fragmentation chain transfer (RAFT) allows blocks ranging from functional to nonfunctional polymers to be made with predictable molecular weight distributions. This article models block formation by varying many of the kinetic parameters. The simulations provide insight into the overall polydispersities (PDIs) that will be obtained when the chain-transfer constants in the main equilibrium steps are varied from 100 to 0.5. When the first dormant block [polymer-S-C(Z)=S] has a PDI of 1 and the second propagating radical has a low reactivity to the RAFT moiety, the overall PDI will be greater than 1 and dependent on the weight fraction of each block. When the first block has a PDI of 2 and the second propagating radical has a low reactivity to the RAFT moiety, the PDI will decrease to around 1.5 because of random coupling of two broad distributions. It is also shown how we can in principle use only one RAFT agent to obtain block copolymers with any desired molecular weight distribution. We can accomplish this by maintaining the monomer concentration at a constant level in the reactor over the course of the reaction. (c) 2005 Wiley Periodicals, Inc.

Design strategies for controlling the molecular weight and rate using reversible addition-fragmentation chain transfer mediated living radical polymerization

Living radical polymerization has allowed complex polymer architectures to be synthesized in bulk, solution, and water. The most versatile of these techniques is reversible addition-fragmentation chain transfer (RAFT), which allows a wide range of functional and nonfunctional polymers to be made with predictable molecular weight distributions (MWDs), ranging from very narrow to quite broad. The great complexity of the RAFT mechanism and how the kinetic parameters affect the rate of polymerization and MWD are not obvious. Therefore, the aim of this article is to provide useful insights into the important kinetic parameters that control the rate of polymerization and the evolution of the MWD with conversion. We discuss how a change in the chain-transfer constant can affect the evolution of the MWD. It is shown how we can, in principle, use only one RAFT agent to obtain a poly-mer with any MWD. Retardation and inhibition are discussed in terms of (1) the leaving R group reactivity and (2) the intermediate radical termination model versus the slow fragmentation model. (c) 2005 Wiley Periodicals, Inc.

A(n-1) Gaudin model with open boundaries

The A(n-1) Gaudin model with integrable boundaries specified by non-diagonal K-matrices is studied. The commuting families of Gaudin operators are diagonalized by the algebraic Bethe ansatz method. The eigenvalues and the corresponding Bethe ansatz equations are obtained. (c) 2005 Elsevier B.V. All rights reserved.

Kinetic study of the thermal degradation of high density polyethylene

The thermal degradation of high density polyethylene has been modelled by the random breakage of polymer bonds, using a set of population balance equations. A model was proposed in which the population balances were lumped into representative sizes so that the experimentally determined molecular weight distribution of the original polymer could be used as the initial condition. This model was then compared to two different cases of the unlumped population balance which assumed unimolecular initial distributions of 100 and 500 monomer units, respectively. The model that utilised the experimentally determined molecular weight distribution was found to best describe the experimental data. The model fits suggested a second mechanism in addition to random breakage at slow reaction rates. (c) 2005 Elsevier Ltd. All rights reserved.

Mechanistic aspects of proton chain transfer: A computational study for the green fluorescent protein chromophore

We explore several models for the ground-state proton chain transfer pathway between the green fluorescent protein chromophore and its surrounding protein matrix, with a view to elucidating mechanistic aspects of this process. We have computed quantum chemically the minimum energy pathways (MEPs) in the ground electronic state for one-, two-, and three-proton models of the chain transfer. There are no stable intermediates for our models, indicating that the proton chain transfer is likely to be a single, concerted kinetic step. However, despite the concerted nature of the overall energy profile, a more detailed analysis of the MEPs reveals clear evidence of sequential movement of protons in the chain. The ground-state proton chain transfer does not appear to be driven by the movement of the phenolic proton off the chromophore onto the neutral water bridge. Rather, this proton is the last of the three protons in the chain to move. We find that the first proton movement is from the bridging Ser205 moiety to the accepting Glu222 group. This is followed by the second proton moving from the bridging water to the Ser205for our model this is where the barrier occurs. The phenolic proton on the chromophore is hence the last in the chain to move, transferring to a bridging “water” that already has substantial negative charge.

T-Q relation and exact solution for the XYZ chain with general non-diagonal boundary terms

We propose that the Baxter's Q-operator for the quantum XYZ spin chain with open boundary conditions is given by the j -> infinity limit of the corresponding transfer matrix with spin-j (i.e., (2j + I)-dimensional) auxiliary space. The associated T-Q relation is derived from the fusion hierarchy of the model. We use this relation to determine the Bethe Ansatz solution of the eigenvalues of the fundamental transfer matrix. The solution yields the complete spectrum of the Hamiltonian. (c) 2006 Elsevier B.V. All rights reserved.

Kinetic studies of the metathesis of 1-hexene using Re2O7/γ-Al2O3 and the synthesis and metathesis of oxazolines

The kinetics of the metathesis of 1-hexene using Re2O7/-Al_2O_3 as the catalyst were investigated under a variety of conditions. The experiments were carried out under high vacuum conditions. The product solutions were characterised by gas liquid chromatography and mass spectroscopy. The initial kinetics of the metathesis of 1-hexene showed that the reaction was first order in the weight of the catalyst and second order in the concentration of 1-hexene. A kinetic scheme which correlated the experimental data with the metallocarbene chain mechanism postulated by Herisson and Chauvin and the kinetics of the reaction was explained using a model based on the Langmuir-Hinshelwood theory. The low conversion of 1-hexene to its products is due to termination reactions which most likely occur by the decomposition of the metallocyclobutane intermediate to produce a cyclopropane derivative and an inactive centre. The optimum temperature for the metathesis of 1-hexene over Re_2O_7/-Al2O3 is 45oC and above this temperature, the rate of metathesis decreases rapidly. Co-catalysts alter the active sites for metathesis so that the catalyst is more selective to the metathesis of 1-hexene. However, the regeneration of metathesis activity is much worse for promoted catalysts than for the unpromoted. The synthesis and metathesis of 4,4-dimethyl-2-allowbreak (9-decenyl)-1,3-oxazoline and 4,4-dimethyl-2-allowbreak (3-pentenyl)-1,3-oxazoline was attempted and the products were analysed by thin layer chromatography, infra-red, 13C and 1H nmr and mass spectroscopy. Obtaining the oxazolines in a good yield with high purity was difficult and consequently metathesis of the impure products did not occur.

Supply chain optimisation of pyrolysis plant deployment using goal programming

This paper presents a goal programming model to optimise the deployment of pyrolysis plants in Punjab, India. Punjab has an abundance of waste straw and pyrolysis can convert this waste into alternative bio-fuels, which will facilitate the provision of valuable energy services and reduce open field burning. A goal programming model is outlined and demonstrated in two case study applications: small scale operations in villages and large scale deployment across Punjab's districts. To design the supply chain, optimal decisions for location, size and number of plants, downstream energy applications and feedstocks processed are simultaneously made based on stakeholder requirements for capital cost, payback period and production cost of bio-oil and electricity. The model comprises quantitative data obtained from primary research and qualitative data gathered from farmers and potential investors. The Punjab district of Fatehgarh Sahib is found to be the ideal location to initially utilise pyrolysis technology. We conclude that goal programming is an improved method over more conventional methods used in the literature for project planning in the field of bio-energy. The model and findings developed from this study will be particularly valuable to investors, plant developers and municipalities interested in waste to energy in India and elsewhere. © 2014 Elsevier Ltd. All rights reserved.

The need for wider supply chain management adoption:empirical results from Ireland

Purpose - This paper aims to provide empirical results which suggest that there is a need for more widespread adoption of supply chain management among Irish firms. Design/methodology/approach - The Republic of Ireland is a small, open, trade-dependent economy and is one of the fastest growing economies in the developed world. However, due to rising costs, there is an increasing trend in Ireland to outsource lower function manufacturing processes to lower-cost locations but to retain high-skill functions (such as R&D). This trend, together with other factors such as its peripheral location, suggests that supply chain management is critical from an Irish perspective. In order to gain unique insights of current levels of awareness/adoption of SCM and the potential impact SCM could have on competitiveness, a survey was conducted among 776 Irish firms. Findings - Overall, the findings suggest that many firms in Ireland pay lip-service to the importance of SCM elements and objectives but the majority of firms, about two thirds, have only a passing understanding of what constitutes SCM. Only 25 per cent adopt SCM programmes and only 9 per cent of Irish companies have a specialised SCM or logistics manager. The gaps in their understanding of SCM are matched by the gaps in their awareness of key costs (e.g. 59 per cent of companies do not know their total supply chain costs). While there are supply chain management adopters in Ireland that are already well up the s-curve of innovation transfer, it is the larger group of less aware companies that must become better at how they manage their supply chains. Originality/value - The paper offers a useful insight into supply chain management and its role in Irish industry. © Emerald Group Publishing Limited.

Pseudoperiodic "Living" and/or controlled cationic ring-opening copolymerization of oxetane with tetrahydropyran:microstructure of polymers vs kinetics of chain growth

The "living" and/or controlled cationic ring-opening bulk copolymerization of oxetane (Ox) with tetrahydropyran (THP) (cyclic ether with no homopolymerizability) at 35°C was examined using ethoxymethyl-1 -oxoniacyclohexane hexafluoroantimonate (EMOA) and (BF3 · CH3OH)THP as fast and slow initiator, respectively, yielding living and nonliving polymers with pseudoperiodic sequences (i.e., each pentamethylene oxide fragment inserted into the polymer is flanked by two trimethylene oxide fragments). Good control over number-average molecular weight (Mn up to 150000 g mol-1) with molecular weight distribution (MWD ∼ 1.4-1, 5) broader than predicted by the Poison distribution (MWDs > 1 +1/DPn) was attained using EMOA as initiating system, i.e., C 2H5OCH2Cl with 1.1 equiv of AgSbF6 as a stable catalyst and 1.1 equiv of 2,6-di-tert-butylpyridine used as a non-nucleophilic proton trap. With (BF3 · CH 3OH)THP, a drift of the linear dependence M n(GPC) vs Mn(theory) to lower molecular weight was observed together with the production of cyclic oligomers, ∼3-5% of the Ox consumed in THP against ∼30% in dichloromethane. Structural and kinetics studies highlighted a mechanism of chains growth where the rate of mutual conversion between "strain ACE species" (chain terminated by a tertiary 1-oxoniacyclobutane ion, Al) and "strain-free ACE species" (chain terminated by a tertiary 1-oxoniacyclohexane ion, Tl) depends on the rate at which Ox converts the stable species T1 (kind of "dormant" species) into a living "propagating" center A1 (i.e., k aapp[Ox]). The role of the THP solvent associated with the suspension of irreversible and reversible transfer reactions to polymer, when the polymerization is initiated with EMOA, was predicted by our kinetic considerations. The activation -deactivation pseudoequilibrium coefficient (Qt) was then calculated in a pure theoretical basis. From the measured apparent rate constant of Ox (kOxapp) and THP (kTHPapp = ka(endo)app) consumption, Qt and reactivity ratio (kp/kd, k a(endo)/ka(exo), and ks/ka(endo) were calculated, which then allow the determination of the transition rate constant of elementary step reactions that governs the increase of Mu with conversion. © 2009 American Chemical Society.

A tranzakciós költségek elmélete és a társadalmi csereelmélet hatásai a bizalomra az ellátási láncban (Affects of Transaction cost and Social Exchange Constructs on trust In supply chain relationship)

A szerzők alapvető feltételezése, hogy az ellátási láncban a bizalom ösztönzi a felek közötti elkötelezettséget. Továbbá a bizalom növeli annak a lehetőségét, hogy az ellátási lánc sikeresen működjön. Ugyanakkor, a felek közötti bizalom hiánya gyakran megnöveli a tranzakciós költségeket, és így csökkenti a hatékonyságot. A cikkben bemutatott kutatás adatgyűjtésére több országban – Franciaországban, Magyarországon, Dél-Koreában, Tunéziában és az Egyesült Államokban – került sor. Összesen 729 érvényes kérdőív érkezett vissza, amelyeket a különböző ellátási láncok résztvevői töltöttek ki. A kutatási eredmények szerint az ellátási láncokon belüli üzleti kapcsolatokban a tranzakciós költségek elméletének összetevői (kapcsolatspecifikusság és viselkedési bizonytalanság), valamint a társadalmi csereelmélet tényezői (lecserélhetőség, észlelt megelégedettség, a partner hírneve és észlelt konfliktus) szoros kapcsolatban állnak a bizalom és az elkötelezettség változóival. _____ This article is based on the assumption that trust promotes commitment between partners in the supply chain and improves the chances of return on supply chain success. In contrast, a lack of trust between them often increases transaction costs and results in inefficiency. The results of this research, based on multi-country surveys with 729 returns from France, Hungary, Korea, Tunisia and the United States on supply chain professionals, reveals a strong affect of transaction cost constructs (TCC) (asset specificity and behavioral uncertainty) and social exchange constructs (SEC) (replaceability, perceived satisfaction, partner reputation, and perceived conflict) on trust-commitment variables in partnership based supply chain relationships. This paper employed a structural equation model to extract information from the survey data. Among the findings, the research indicates that a firm’s trustcommitment in dealing with their supply chain partnership is highly associated with not only transaction cost, but more so with social exchange variables. This study may open a new research avenue in that there is another construct, SEC, beside TSC that influences the degree of trust and commitment.

A bizalmat befolyásoló tényezők vizsgálata az üzleti kapcsolatokban (Affects of Transaction cost and Social Exchange Constructs on trust In supply chain relationship)

Az üzleti célú kapcsolatok vizsgálatakor legtöbbször felmerül a bizalom fogalma is, amellyel először a szociálpszichológia és a szociológia foglalkozott. A szerző cikkében azzal foglalkozik, hogy milyen tényezők befolyásolják a bizalmat az üzleti kapcsolatokban. Ezért magyarországi szervezeteket (elsősorban üzleti vállalkozásokat) kérdezett meg kvantitatív módszer alkalmazásával. Ez az empirikus kutatás igyekszik a bizalom lehető legtöbb tényezőit összegyűjteni, ahol a kérdőívben a válaszolók egyik létező – vevői vagy beszállítói – kapcsolatukra gondolva válaszoltak a bizalmon túl a partner hírnevére, az észlelt elégedettségre és konfliktusra, az információcserére, a lecserélhetőségre, valamint a kapcsolatspecifikus beruházásokra vonatkozóan. Az eredmények azt mutatják, hogy egyik változó sem jelent kizárólagos befolyásoló erőt, hanem közösen alakítják ki a bizalom adott szintjét. _______ This article is based on the assumption that trust promotes commitment between partners in the supply chain and improves the chances of return on supply chain success. In contrast, a lack of trust between them often increases transaction costs and results in inefficiency. The results of this research, based on multi-country surveys with 729 returns from France, Hungary, Korea, Tunisia and the United States on supply chain professionals, reveals a strong affect of transaction cost constructs (TCC) (asset specificity and behavioral uncertainty) and social exchange constructs (SEC) (replaceability, perceived satisfaction, partner reputation, and perceived conflict) on trust-commitment variables in partnership based supply chain relationships. This paper employed a structural equation model to extract information from the survey data. Among the findings, the research indicates that a firm’s trustcommitment in dealing with their supply chain partnership is highly associated with not only transaction cost, but more so with social exchange variables. This study may open a new research avenue in that there is another construct, SEC, beside TSC that influences the degree of trust and commitment.

Value creation and appropriation through the Hungarian SME’s food chain

Value creation is the result of the continuous innovation activity of the entrepreneur, which is carried out mainly in form of open innovation among the agri-food SMEs. However value creation is not the ultimate goal of the enterprises. They are more interested in increased appropriation of the created value. Although the value creation (innovation) is very well explored and cultivated area of research, there are some voids in the field of agriculture and food industry: the behavioural aspect of open innovation is very rare. The value capturing is even much less studied, therefor our research approach is largely explorative one. Data are drawn from a survey carried out in Hungary among the agri-food SMEs in 2014. We use Structural Equation Modelling as well as ordered probit and semi-non parametric ordered probit models for analysing the data. Our results show that there is positive relationship between the knowledge sharing with chain partners and the innovativeness. We could explore that size of the firm, absorptive capacity and openness to foreign trade ambiguously affects value capturing. However trust in chain partners, reciprocity in knowledge sharing with chain partners and willingness to cooperate with buyers positively influence the appropriation of the created value.