α,ω-Bis(2,3-epoxypropyl)oligooxyethylene-based crosslinked resins as solid-liquid phase-transfer catalysts

α,ω-Diglycidyl-oligoethylenoxides were prepared by reacting α,ω-dihydroxy-oligoethylenoxides with epichlorohydrin. They were then crosslinked with triethylenetetramine to form catalyst beads which were tested for their liquid-solid phase-transfer catalyst activity in the reaction of 1-bromobutane with potassium phenoxide. Regardless of the oxyethylene chain length, the catalyst beads showed significant activity, which was relatively high for oligomers with a great number of oxyethylene repeating units.     

Assembly of the 68- and 72-kD proteins of signal recognition particle with 7S RNA

Signal recognition particle (SRP), the cytoplasmic ribonucleoprotein particle that mediates the targeting of proteins to the ER, consists of a 7S RNA and six different proteins. The 68- (SRP68) and 72- (SRP72) kD proteins of SRP are bound to the 7S RNA of SRP as a heterodimeric complex (SRP68/72). Here we describe the primary structure of SRP72 and the assembly of SRP68, SRP72 and 7S RNA into a ribonucleoprotein particle. The amino acid sequence deduced from the cDNA of SRP72 reveals a basic protein of 671 amino acids which shares no sequence similarity with any protein in the sequence data libraries. Assembly of SRP72 into a ribonucleoprotein particle required the presence of 7S RNA and SRP68. In contrast, SRP68 alone specifically bound to 7S RNA. SRP68 contacts the 7S RNA via its NH2-terminal half while COOH-terminal portions of SRP68 and SRP72 are in contact with each other in SRP. SRP68 thus serves as a link between 7S RNA and SRP72. As a large NH2-terminal domain of SRP72 is exposed on SRP it may be a site of contact to other molecules involved in the SRP cycle between the ribosome and the ER membrane.     

The effective promotion of informal control in information systems offshoring projects

As firms increasingly engage in interorganizational information systems (IS) projects, including IS offshoring projects, the challenge for client firms of effectively exercising control across organizational boundaries becomes critical. Although the importance of informal controls (clan and self-control) in this context has been recognized, prior research has focused primarily on formal controls. Consequently, our understanding of the use of clan and self-control in interorganizational IS projects is scarce, and partly inconsistent or contradictory. This study focuses the client’s role in promoting informal controls in interorganizational projects involving distant client–vendor relationships as well as the effectiveness of such controls. We use matched-pair survey data from 86 IS offshoring projects involving client and vendor relationship managers. Our results show an interesting pattern: while clan control is considerably more difficult to promote than self-control in client–vendor project relationships, only clan control has a direct positive impact on project performance. Moreover, formal control modes, national cultural values, and project context factors moderate both the promotion and the effectiveness of informal controls. Our study’s main contributions lie in establishing the relevance of the distinction between informal control given and received, and the importance of the client’s role in promoting informal controls.     

Influence of composition and particle size on spin dynamics and thermodynamic properties of magnetoresistive perovskites

The thermodynamic behavior and spin dynamics of the colossal magnetoresistive (CMR) perovskites of general formula La(1-x)(A)xMn(1-y)(B)yO3 (where A is an alkaline earth, and B = Al, In) have been studied in order to evidence the effect of composition and the influence of nanocrystallinity on the thermodynamic and magnetic characteristics. By using electron paramagnetic resonance (EPR) spectroscopy, the behavior of the exchange coupling integral (J) between Mn spins and the polaron activation energy (Ea) have been investigated. The thermodynamic properties represented by the relative partial molar free energies, enthalpies and entropies of oxygen dissolution in the perovskite phase, as well as the equilibrium partial pressures of oxygen have been obtained by using solid electrolyte electrochemical cells method. The influence of the oxygen stoichiometry change on the thermodynamic properties was examined using the data obtained by a coulometric titration technique coupled with measurements of the electromotive force (EMF). The results were correlated with the average Mn valence values as determined by redox titration. The properties of the rare-earth manganites are strongly affected by the A- and B-site substitution and by the oxygen nonstoichiometry. New features related to the modifications in properties connected with the nanocrystalline state were evidenced. The correlation existing between the magnetic and thermodynamic characteristics were discussed in relation to significant changes in the overall concentration of defects.     

A novel contextual memory algorithm for edge detection

Pattern Analysis and Applications - Edge detection plays an important role in many computer vision systems. In this paper, we propose a novel application agnostic algorithm for prediction of...     

Transformation of stainless steel slag toward a reactive cementitious binder

Argon oxygen decarburization (AOD) slag represents more than 50 wt% of the slag from stainless steel production. Although some applications are available, e.g., as aggregates for road constructions or fertilizers, they are characterized by low economic value and limited applicability. In order to increase the economic value of AOD slag, alternative applications have been proposed, e.g., as partial or full replacement for Ordinary Portland Cement (OPC). The work presented here investigates whether the adaptation of the AOD slag chemistry within a high temperature process leads to an improvement of its hydraulic properties and thereby can demonstrate its potential to be converted into a hydraulic binder suitable for OPC replacement. For this purpose, three synthetic AOD slags with basicities (CaO/SiO₂) of 2.0, 2.2, and 2.4 were synthesized, and the effect of the CaO/SiO₂ ratio on the material stability, the amount of tricalcium silicate formed, and their hydraulic properties investigated. X‐ray diffraction, scanning electron microscope (SEM), and isothermal calorimetry analysis were used to characterize the microstructure and the hydraulic activity. The results show that the proposed method is indeed a promising way to stabilize a stainless steel AOD slag and convert it into a hydraulic binder.     

An examination of “citation circles” for social sciences journals in Eastern European countries

This study aims to explore the effects of both journal self citations and mutual citations within a group of journals on the increase in the impact factors (IFs) for social sciences journals published in Eastern Europe. We found that the practice of mutual citations is prevalent among the new journals, a trend that raises questions about possible manipulation of the IF and potential isolation of the recent journals from the international network of scholarly communication.     

Dynamic modeling and validation of a biomass hydrothermal pretreatment process—a demonstration scale study

Hydrothermal pretreatment of lignocellulosic biomass is a cost effective technology for second generation biorefineries. The process occurs in large horizontal and pressurized thermal reactors where the biomatrix is opened under the action of steam pressure and temperature to expose cellulose for the enzymatic hydrolysis process. Several by‐products are also formed, which disturb and act as inhibitors downstream. The objective of this study is to formulate and validate a large scale hydrothermal pretreatment dynamic model based on mass and energy balances, together with a complex conversion mechanism and kinetics. The study includes a comprehensive sensitivity and uncertainty analysis, with parameter estimation from real‐data in the 178–185°C range. To highlight the application utility of the model, a state estimator for biomass composition is developed. The predictions capture well the dynamic trends of the process, outlining the value of the model for simulation, control design, and optimization for full‐scale applications. © 2015 American Institute of Chemical Engineers AIChE J, 61: 4235–4250, 2015     

Free radical polymerization of vinyl acetate in the presence of liquid polysulfides

The free radical polymerization of vinyl acetate in the presence of a liquid polysulfide H(SCH₂CH₂OCH₂OCH₂CH₂S)_nH (thiocol) was investigated from the point of view of reaction mechanism and characterization of the resulting copolymers. It was shown that, besides the thiol end groups that were consumed very rapidly, the disulfide groups within the thiocol chain were also involved in chain transfer processes. The chain transfer constant of the thiocol S–S groups in the polymerization reaction was estimated from their rate of consumption versus the rate of monomer consumption (C_T = 0.89). The resulting copolymers, made up of randomly distributed thiocol sequences and PVAc blocks, were characterized by ¹H NMR, GPC, DSC and TGA measurements. The copolymers displayed only one glass transition each, which decreased as the PVAc block length decreased, while their thermal stability was lower than that of both thiocol and PVAc. The molecular weight of the copolymers increased with VAc conversion as a consequence of the insertion of PVAc blocks within the thiocol chain.