One‐component thioxanthone‐based polymeric photoinitiators

The photochemical and photophysical properties of new polymeric photoinitiators (PPIs) containing pendant thioxanthone (TX) and amine moieties are studied. The PPIs are synthesized by copolymerization of tert‐butyl 2‐((9‐oxo‐9H‐thioxanthen‐2‐yloxy)methyl)acrylate (TX1) with N,N‐dimethylaminoethyl methacrylate (DMAEM) at two different ratios using free radical polymerization. UV–vis spectra indicate that PPIs possess similar absorption characteristics to TX1 in the violet range (～400 nm; absorption red‐shift 20 nm). The photochemical mechanisms are studied by electron spin resonance (ESR), steady state photolysis, laser flash photolysis, and cyclic voltammetry. ESR studies indicate formation of two different aminoalkyl radicals on the hydrogen donor amine. The triplet state of the PPIs is short‐lived compared to isopropyl thioxanthone and TX1, due to the built‐in amine functionality. Photopolymerization of trimethylolpropane triacrylate (TMPTA) initiated by these photoinitiators under LED exposure at 385 and 405 nm using real‐time FTIR spectroscopy shows that they exhibit higher efficiency than TX/N‐methyldiethanolamine (MDEA) and TX1/MDEA systems with the advantage of a much higher molecular weight that can be very helpful to overcome migration issues. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3370–3378     

An intermodal multicommodity routing problem with scheduled services

We study a multicommodity routing problem faced by an intermodal service operator that uses ground and maritime transportation. Given a planning horizon, a?set of commodities to be picked up at their release times and to be delivered not later than their duedates, the problem is to decide on routes for these commodities using trucks and scheduled and capacitated maritime services at minimum cost of transportation and stocking at the seaports. Two mixed integer programming formulations and valid inequalities are proposed for this problem. The results of a computational study to evaluate the strength of the linear programming relaxations and the solution times are reported.     

Solid phase extraction and determination of nickel in water samples by using novel thiol-containing sulfonamide polymeric resin and atomic absorption spectrophotometer

Interest in preconcentration techniques for the determination of metals at ultratrace levels still continues increasingly because of some disadvantages of flameless atomic absorption spectrometry as well as the high costs of other sensitive methods in compared to flame atomic absorption spectrometry.In this study,thiol-containing sulfonamide resin was synthesized,characterized and applied as a new sorption material for solid phase extraction of nickel in drinking water samples.After preconcentration procedure,flame atomic absorption spectrometry was used for determinations.Optimum parameters were found to be pH=3.2,contact time =20 min and eluate volume=3 mL.The limit of detection was found to be 0.75 ng · mL-1.The synthesized resin exhibits the superiority in compared to the other adsorption reagents because of the fact that there is no necessity of any complexing reagent,high sorption capacity as well as the relatively fast extraction rate.The Ni concentrations in the studied 21 kind of water samples were found to be in the range of BDL-4.0 ng ·mL-1.     

Matching patient and physician preferences in designing a primary care facility network

This paper introduces an integer programming model for planning primary care facility networks, which accounts for the interests of different stakeholders while maximizing access to health care. Physician allocation to health-care facilities is explicitly modelled, which allows consideration of physician incentives in the planning phase. An illustrative case study in the Turkish primary care system is presented to show the implications of focusing on patient or physician preferences in the planning phase. A discussion of trade-offs between the different stakeholder preferences and some recommendations for modelling choices to match these preferences are provided. In the context of this case, we found that using an access measure that decays with distance, and incorporating nearest allocation constraints improves performance for all stakeholders. We also show that increasing the number of physicians may have adverse affects on access measures when physician preferences are addressed.     

Effects of microwaves on the dehydration characteristics of santite

In this paper, by using the microwave irradiation, the dehydration curves of santite (KB₅O₈·4H₂O) were obtained and modeled. By using a different mathematical model, the kinetic parameters of the dehydration process were determined. The dehydration of santite was completed at 180, 105 and 60 min for 360, 600 and 800 W, respectively. The characterization techniques of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopy were applied to the obtained santite mineral and dehydrated santite mineral. From the obtained XRD analysis, santite, its powder diffraction file number is 01-072-1688 transformed into an amorphous phase after the microwave dehydration process. From the FT-IR and Raman analyses, it can be said that partial dehydration was achieved due to the disappearance of structural H₂O bands but remaining some hydroxyl bands. For the modeling results, Verma model best fits the experimental data obtained from the dehydration and the dehydration activation energy was calculated as 11.92 kW?×?g^–1.

     

Multi-period supplier selection under price uncertainty

We consider a problem faced by a procurement manager who needs to purchase a large volume of multiple items over multiple periods from multiple suppliers that provide base prices and discounts. Discounts are contingent on meeting various conditions on total volume or spend, and some are tied to future realizations of random events that can be mutually verified. We formulate a scenario-based multi-stage stochastic optimization model that allows us to consider random events such as a drop in price because of the most favoured customer clauses, a price change in the spot market or a new discount offer. We propose certainty-equivalent heuristics and evaluate the regret of using them. We use our model for three bidding events of a large manufacturing company. The results show that considering most favored customer clauses in supplier offers may create substantial savings that may surpass the savings from regular discount offers.     

Plasma treatment of polypropylene fabric for improved dyeability with soluble textile dyestuff

The impact of plasma treatment parameters on the surface morphology, physical-chemical, and dyeing properties of polypropylene (PP) using anionic and cationic dyestuffs were investigated in this study. Argon plasma treatment was used to activate PP fabric surfaces. Activated surfaces were grafted different compounds: 6-aminohexanoic acid (6-AHA), acrylic acid (AA), ethylendiamine (EDA), acryl amide (AAMID) and hexamethyldisiloxane (HMDS). Compounds were applied after the plasma treatment and the acid and basic dyeing result that was then observed, were quite encouraging in certain conditions. The possible formed oxidizing groups were emphasized by FTIR and ATR and the surface morphology of plasma treated PP fibers was also investigated with scanning electron microscopy (SEM).PP fabric could be dyed with acid and basic dyestuffs after only plasma treatment and plasma induced grafting, and fastnesses of the dyed samples were satisfactory.     

Synthesis,photophysical and antioxidant properties of pyrrolo[3,2-c]carbazole and dipyrrolo[3,2-c:2′,3′-g]carbazole compounds

Research on Chemical Intermediates - The synthesis of (6-ethyl-1,6-dihydropyrrolo[3,2-c]carbazol-2-yl)methanol 5 and...     

Quantification and identification of components released from dental composites using different chromatographic techniques

This study aimed to review recent chromatographic methods for quantifying and identifying components released from dental composites. Resin-based dental restorative materials are extensively used in dentistry today. Although composite materials are known to be highly stable structures, they are susceptible to degradation because of the incomplete polymerization. Several components may be released from resin composite restorations into the oral environment. The elution of components from composite resins may affect the biocompatibility of the restorations. Therefore, it is essential to understand the nature and quantity of substances that are segregated into the oral cavity.     

Barriers to internal rotation around the C-N bond in 3-(o-aryl)-5-methyl-rhodanines using NMR spectroscopy and computational studies. Electron density topological analysis of the transition states

We have investigated the pairs of rotational isomers for six 3-(o-aryl)-5-methyl-rhodanines (Z = H, F, Cl, Br, OH, and CH3) using NMR spectroscopy and density functional theory (DFT) calculations. Electron density topological and NBO analysis has demonstrated the importance of non-covalent interactions, characterised by (3, -1) bond critical points (BCPs), between the oxygen and sulfur atoms on the thiazolidine ring with the aryl substitutents in stabilizing the transition states. The energetic activation barriers to rotation have also been determined using computational results; rotational barriers for 3-(o-chlorophenyl)-5-methyl-rhodanine (3S) and 3-(o-tolyl)-5-methyl-rhodanine (6S) were determined experimentally based on NMR separation of the diastereoisomeric pairs, and the first-order rate constants used to derive the value of the rotational barrier from the Eyring equation.