Novel poly(vinyl chloride) based thermoplastic elastomers incorporating vinyl-functionalized silicone rubber

ABSTRACT

Novel poly(vinyl chloride) (PVC) based thermoplastic elastomers were developed by blending with different proportions of vinyl-functionalized silicone rubber. Scanning electron microscopy (SEM) confirmed good compatibility between PVC and silicone rubber which allowed enhancement of the stress-strain behavior. On the contrary to neat PVC, exposure to heat or UV radiation was found not to cause any considerable deterioration to the stress-strain behavior. Fourier Transform Infrared (FTIR) revealed a possible chemical interaction between the blend components involving the vinyl groups from the silicone rubber, which is thought to be the reason for maintaining the mechanical properties unaltered. Further investigation with ultraviolet-visible (UV-Vis.) spectroscopy signified absence of intensive dehydrochlorination usually encountered for PVC after exposure to heat or UV radiation, which indicates a potential stabilizing effect for the silicone rubber and build up of a network structure comprising both hard and soft segments.     

Effect of deterioration on the instantaneous replenishment model with imperfect quality items

The assumptions required to justify the use of the economic order quantity model (EOQ) are rarely met. To provide mathematical models that more closely represent real-life situations, these assumptions must be relaxed. Among these assumptions are, first, items stocked are of perfect quality, and second, they preserve their characteristics during their stay in inventory. This paper considers a modified EOQ-type inventory model for a deteriorating item with unreliable supply. That is, a percentage of the on-hand inventory is wasted due to deterioration. Moreover, orders may contain a random proportion of defective items, which follow a known distribution. As soon as an order is received, a retailer conducts a screening process to identify imperfect quality items, which are salvaged as a single batch at the end of the screening process. First, a mathematical model is developed, assuming that no shortages are allowed. For that, it is assumed that the inventory level when placing an order is just enough to cover the demand during the screening period. The concavity of the profit function is established and sensitivity analysis is provided to analyze the impact of changing various model parameters on the optimal order quantity and profit. Then, the assumption of no shortages is relaxed, and a model is developed to incorporate backorders. We analyze the model with backorders numerically and provide managerial insights.     

Analytical properties of resource-bounded real functionals

Computable analysis is an extension of classical discrete computability by enhancing the normal Turing machine model. It investigates mathematical analysis from the computability perspective. Though it is well developed on the computability level, it is still under developed on the complexity perspective, that is, when bounding the available computational resources. Recently Kawamura and Cook developed a framework to define the computational complexity of operators arising in analysis. Our goal is to understand the effects of complexity restrictions on the analytical properties of the operator. We focus on the case of norms over C[0, 1] and introduce the notion of dependence of a norm on a point and relate it to the query complexity of the norm. We show that the dependence of almost every point is of the order of the query complexity of the norm. A norm with small complexity depends on a few points but, as compensation, highly depends on them. We briefly show how to obtain similar results for non-deterministic time complexity. We characterize the functionals that are computable using one oracle call only and discuss the uniformity of that characterization.     

Excimer laser-assisted chemical process for formation of hydrophobic surface of Si (001)

Silicon (Si) wettability is one of the important parameters in the development of Si-based biosensing and lab-on-chip devices. We report on UV laser induced hydrophobicity of Si (001) wafers immersed in methanol during the irradiation with an ArF excimer laser. The irradiation with 800 pulses of the laser operating at 65 mJ/cm² allowed to significantly increase the hydrophobicity of investigated samples as characterized by the static contact angle change from 77° to 103°. Owing to the irradiation with relatively low laser fluence, no measurable change in surface morphology of the irradiated samples has been observed with atomic force microscopy measurements. The nature of the hydrophobic surface of investigated samples is consistent with X-ray photoelectron spectroscopy analysis that indicates formation of Si–O–CH₃ bonds on the surface of the laser-irradiated material.     

Photocatalytic formulations for protein fibers: experimental analysis of the effect of preparation on compatibility and photocatalytic activities

In this article, we report an optimization study of a photocatalytic self-cleaning sol–gel formulation. In particular we studied the effect of formulation preparation time on the formation of anatase titanium dioxide sol and its compatibility to protein keratin-type wool fibers. The sols were formed by a low temperature sol–gel process. The nucleated anatase was characterized by UV–vis transmission, particle size distribution, X-ray diffraction, and transmission electron microscopy. The compatibility between the formulations and wool fibers is evaluated by field-emission scanning electron microscopy, UV transmission, and mechanical properties. The photocatalytic self-cleaning activity of coated fibers and its reproducibility are also discussed.     

Comparison of two innovatives approaches for bacterial detection: paramagnetic nanoparticles and self-assembled multilayer processes

Transfusion medicine is a field that has developed in the second half of the last century. Very rapidly, however, it became clear that this approach also carried its problems, such as the incompatibility of red blood cells and plasma between donors and recipients, and the possibility of transmitting viral and bacterial infections. An immunomagnetic biosensor for the label-free detection of a bacterial model, Escherichia coli, is described and compared to a self assembled multilayer system reported previously. The paramagnetic nanoparticles layer attracted to, and formed on, the gold electrode surface via a magnetic field up to 300 mT is not totally blocking for the redox probe comparing to the thiol self assembled monolayer (a biotin thiol and a spacer thioalcohol). Moreover, the modeling of the Nyquist spectra obtained by electrochemical impedance spectroscopy for increasing concentrations of E. coli shows for both system a sigmoid variation of the polarization resistance with increasing logarithmic concentration of bacteria. A sensitivity slope of 10.675 was obtained for the immunomagnetic sensor compared to 6.832 for the self assembled multilayer process, this indicating the higher sensitivity of the paramagnetic nanoparticles biosensor.     

Profit maximizing coalitions with shared capacities in distribution networks

We study the distribution network structure of multiple firms in the context of demand sensitivity to market offers. The problem consists in determining the profitability of horizontal collaboration between firms in a collaborative distribution schema. It considers the case of a set of regional distribution centers (DCs) where each DC is initially dedicated solely to one firm’s distribution activities and studies when it is beneficial that the DC owners collaborate through sharing their storage-throughput capacity. Such strategic decisions are made in order to improve the distribution capabilities of firms in terms of response time and cost-efficiency compared to the stand-alone situation. The problem is modeled as a coalition formation game in a cooperative framework, and we propose a collaborative distribution game with profit maximization. Three sharing mechanisms are modeled and tested: egalitarian allocation, proportional allocation, and Shapley value. The collaboration decision conditions for a given firm are analytically derived according to the sharing method considered and used to enhance the solution approach. Our numerical results clearly highlight the impact of this innovative collaboration opportunity on the firms’ performance in terms of distribution cost savings and revenue increases. An observed behavior is that the formation of several sub-coalitions prevails over the formation of a grand coalition, and that different cost sharing methods can lead to different sub-coalitions. We also provide managerial insights on the appropriate size of a coalition in various business instances tested, and on the key drivers that foster horizontal collaborative behavior among firms.     

Synthesis and anticancer activity of some new pyridine derivatives

Different substituents were introduced in positions 2 and 6 of 2,6 diaminopyridine in order to obtain new heterocyclic compounds. A new series of aza pyridine, imidazopyridine, benzodiazepine, indole, pyrimidine, and benzimidazole heterocyclic derivatives were synthesized in good yields. The anticancer activities of some of the new compounds were evaluated against liver cancer cell line HEPG2. Compounds 3, 4, 10, 11, 12, and 17 showed the highest activity when compared to 5-flurouracil (5-FU) and doxorubicin (DOX) chemotherapy.