Coordinating a supply chain with effort and price dependent stochastic demand

This paper investigates the issue of channel coordination for a supply chain facing stochastic demand that is sensitive to both sales effort and retail price. In the standard newsvendor setting, the returns policy and the revenue sharing contract have been shown to be able to align incentives of the supply chain’s members so that the decentralized supply chain behaves as well as the integrated one. When the demand is influenced by both retail price and retailer sales effort, none of the above traditional contracts can coordinate the supply chain. To resolve this issue, we explore a variety of other contract types including joint return policy with revenue sharing contract, return policy with sales rebate and penalty (SRP) contract, and revenue sharing contract with SRP. We find that only the properly designed returns policy with SRP contract is able to achieve channel coordination and lead to a Pareto improving win–win situation for supply chain members. We then provide analytical method to determine the contract parameters and finally we use a numerical example to illustrate the findings and gain more insights.     

Binding of acetylcholinesterase to multiwall carbon nanotube-cross-linked chitosan composite for flow-injection amperometric detection of an organophosphorous insecticide

A novel method for immobilization of acetylcholinesterase (AChE) by binding covalently to a cross-linked chitosan-multiwall carbon nanotube (MWNT) composite is described. In addition a sensitive, fast, cheap and automatizable flow injection detection of an organophosphorous insecticide was developed. The MWNTs were homogeneously distributed in the chitosan membrane which showed a homogeneous porous structure. The immobilized AChE could catalyze the hydrolysis of acetylthiocholine with a K(M)app value of 177 microM to form thiocholine, which was then oxidized to produce detectable signal in a linear range of 1.0-500 microM and fast response. MWNTs could catalyze the electrooxidation of thiocholine, thus increasing detection sensitivity. Based on the inhibition of an organophosphorous insecticide on the enzymatic activity of AChE, using Sulfotep as a model compound, the conditions for the flow-injection detection of the insecticide were optimized. Both biocompatibility of chitosan and inherent conductive properties of MWNTs favored the detection of the insecticide from 1.5 to 80 microM along with good stability and reproducibility. 95 % reactivation from inhibited AChE could be regenerated by using 2-pyridinealdoxime methiodide within 15 min for 15 times. The detection of Sulfotep samples exhibited satisfactory results. The proposed flow-injection analysis device can be applied to automated determination and characterization of enzyme inhibitors.     

Theoretical studies on the structures, thermodynamic properties, detonation properties, and pyrolysis mechanisms of spiro nitramines

Density function theory (DFT) has been employed to study the geometric and electronic structures of a series of spiro nitramines at the B3LYP/6-31G level. The calculated results agree reasonably with available experimental data. Thermodynamic properties derived from the infrared spectra on the basis of statistical thermodynamic principles are linearly correlated with the number of nitramine groups as well as the temperature. Detonation performances were evaluated by the Kamlet-Jacobs equations based on the calculated densities and heats of formation. It is found that some compounds with the predicted densities of ca. 1.9 g/cm3, detonation velocities over 9 km/s, and detonation pressures of about 39 GPa (some even over 40 GPa) may be novel potential candidates of high energy density materials (HEDMs). Thermal stability and the pyrolysis mechanism of the title compounds were investigated by calculating the bond dissociation energies (BDE) at the B3LYP/6-31G level and the activation energies (E(a)) with the selected PM3 semiempirical molecular orbital (MO) based on the unrestricted Hartree-Fock model. The relationships between BDE, E(a), and the electronic structures of the spiro nitramines were discussed in detail. Thermal stabilities and decomposition mechanisms of the title compounds derived from the B3LYP/6-31G BDE and the UHF-PM3 E(a) are basically consistent. Considering the thermal stability, TNSHe (tetranitrotetraazaspirohexane), TNSH (tetranitrotetraazaspiroheptane), and TNSO (tetranitrotetraazaspirooctane) are recommended as the preferred candidates of HEDMs. These results may provide basic information for the molecular design of HEDMs.     

Association between excision repair cross-complementation group 1 polymorphism and clinical outcome of platinum-based chemotherapy in patients with epithelial ovarian cancer

ERCC1 is a DNA repair gene and has been associated with resistance to DNA damaging agents. In this study we hypothesized that a polymorphism of ERCC1 Asn118Asn (C -> T) might affect the platinum-resistance of epithelial ovarian cancer patients to platinum-taxane chemotherapy administered postoperatively. Using the SNapShot assay, we assessed this polymorphism in ERCC1 in 60 ovarian cancer patients. Platinum-resistance was defined as progression on platinum-based chemotherapy or recurrence within 6 months of completing therapy. Although not significant, platinum-resistance was less frequently observed in patients with the C/T+T/T genotype (P=0.064). Multivariate analysis showed that the C/T+T/T genotypes constituted an independent predictive factor of reduced risk of platinum-resistance in ovarian cancer (odds ratio 0.17, 95% confidence interval 0.04-0.74, P=0.018, Fisher's exact test). No significant correlation was observed between overall survival and the ERCC1 polymorphism. Our results suggest that genotyping of the ERCC1 polymorphism Asn118Asn may be useful for predicting the platinum-resistance of epithelial ovarian cancer patients. However, these findings require prospective confirmation.     

An antioxidant modulates expression of receptor activator of NF-kappaB in asthma

Oxidative stress plays critical roles in airway inflammation that is usually accompanied by increased vascular permeability and plasma exudation. VEGF increases vascular permeability and leads to airway inflammation. In addition, VEGF has been shown to enhance receptor activator of NF-kappaB (RANK) expression in endothelial cells. An aim of the study was to determine the potential role of antioxidant in the regulation of RANK expression in murine model of asthma. We have used a C57BL/6 mouse model of allergic asthma to evaluate the effect of L-2-oxothiazolidine-4-carboxylic acid (OTC), a prodrug of cysteine, which acts as an antioxidant, and VEGF receptor inhibitor on RANK mRNA expression. The mice develop the following pathophysiological features of asthma in the lungs: increased expression of RANK mRNA, increased number of inflammatory cells of the airways, increased vascular permeability, and increased levels of VEGF. Administration of OTC and VEGF receptor inhibitor markedly reduced plasma extravasation and VEGF levels in allergen-induced asthmatic lungs. We also showed that the increased RANK mRNA expression at 72 h after ovalbumin inhalation were reduced by the administration of OTC or VEGF receptor inhibitor. The results indicate that OTC and VEGF receptor inhibitor which inhibit up-regulation of VEGF expression modulate RANK expression that may be in association with the regulation of vascular permeability, and suggest that VEGF may regulate the RANK expression. These findings provide a crucial molecular mechanism for the potential use of antioxidants to prevent and/or treat asthma and other airway inflammatory disorders.     

An O-GlcNAcase-specific inhibitor and substrate engineered by the extension of the N-acetyl moiety

A novel analogue of PUGNAc, a potent O-GlcNAcase inhibitor, was synthesized and analyzed as an inhibitor of O-GlcNAcase, hexosaminidase A, and hexosaminidase B. While PUGNAc does not demonstrate selective inhibition of these related enzymes, the extension of the acetyl moiety to the longer butyl chain provided a compound with depressed inhibition of O-GlcNAcase and no observed inhibition of either hexosaminidase A or hexosaminidase B. Further, we applied this knowledge of substrate recognition at the N-acetyl group to our recently reported fluorogenic substrate for monitoring O-GlcNAcase activity. Gratifyingly, this altered small molecule was demonstrated to be a potent substrate for O-GlcNAcase while possessing no activity at hexosaminidase A. This reagent provides, for the first time, a means for monitoring O-GlcNAcase activity independent of the related enzymes hexosaminidase A and hexosaminidase B.     

Photopolymer microtips for efficient light coupling between single-mode fibers and photonic crystal fibers

A novel method for light coupling between single-mode fibers (SMFs) and small-core photonic crystal fibers (PCFs) is demonstrated. The method is based on growing photopolymer microtips directly on the end faces of SMFs. The shape and size of the tips can be controlled by adjusting the laser power and the exposure time for polymerization to match the mode field to the small-core PCFs. A 5 dB improvement in coupling efficiency between a SMF and a commercial small-core, highly nonlinear PCF is experimentally demonstrated. This compact and efficient butt-coupling method is particularly suitable for PCF gas sensor applications.     

Stimulus responsive fluorescent hyperbranched polymers and their applications

Fluorescent hyperbranched polymers (FHBPs), which combine the versatile fluorescent property with unique characteristics of hyperbranched architecture, are desirable candidates for stimulus responsive materials. This review demonstrates the structure and environment-dependent emission behaviors of a series of FHBPs. AEE active FHBPs showing opposite performance to ACQ effect are used to sensitively detect explosives and a superamplification effect is found. Specially designed FHBPs can complex with metal ions, leading to fluorescence turn-off due to complex quenching effect. The protonation of amino-containing FHBPs exhibits pH-dependent fluorescence responses to solution acidity. Some FHBPs containing responsive moieties are photo- and thermo-sensitive, and show potential applications as smart materials.