Green Procurement Relationships Development under Carbon Emissions Regulations: A Bi-Level Programming Approach.

A multi-period Stackelberg game is adopted to study a green procurement relationship between manufacturers and suppliers in a supply chain. The manufacturers are considered as leaders, while the suppliers are modelled as followers in this Stackelberg game. Accordingly, a mixed binary linear bi-level programming model is developed to elaborate the game in consideration of carbon tax scheme. The upper level (the leader) aims at selecting a proper number of suitable suppliers to provide heterogeneous raw materials at the lowest operational cost. The objective of the lower level (the follower) is to find optimal purchasing quantities of raw materials. In addition, two lemmas are introduced to transform the mixed linear bi-level programming model into a single level linear programming model. The numerical example illustrates that: (1) the manufacturer prefers to adopt the multiple sourcing strategy due to the flexibility; (2) keeping stable supplies and large order volumes could effectively reduce carbon emissions for the suppliers and make the supply chain greener.

[Effect of Yuyin Ruangan Granule on TGF-ß1 expression in hepatic fibrosis rats].

OBJECTIVES: To observe the preventive and therapeutic action of Yuyin Ruangan Granule (YRG, Traditional Chinese Medicine) in hepatic fibrosis rats model and its effect on transforming growth factor-ß1 (TGF-ß1) expression. METHODS: The Wistar rats were randomly divided into 6 group (n=10), and the model of hepatic fibrosis rats was established by subcutaneous injected with carbon tetrachloride (CCL4), fed on high-fat diet and 20% ethanol for 6 weeks, to survey the effect and mechanism of YRG preventing hypatic fibrosis by detecting liver function (the activity of alanine aminotransferase(ALT), aspartate aminotransferase(AST), etc.) of liver fibrosis rats, liver fibrosis indicators (hyaluronic acid, Ⅲ procollagen, type IV collagen, laminin and hepatic pathology, etc.), and TGF-ß1 expression in liver tissue after 6 weeks treated with YRG through intragastric administration (q. d.). RESULTS: At the 7th week, fibrotic lesions appears distinctly in liver tissue of model group compared with control group (P<0.01), YRG of 6.2~28.8 g/kg could significantly decrease hepatic index, ALT and AST activities, content of hyaluronic acid(HA), Ⅲ procollagen (PCⅢ), type Ⅳ collagen(C-Ⅳ), laminin (LN) in serum, relieve liver fibrosis pathological changes and inhibit TGF-ß1 expression in fibrotic liver tissue (P<0.05, P<0.01). CONCLUSIONS: YRG has significantly preventive effects on liver fibrosis rats model, and it may be one of its mechanisms to inhibit expression of TGF-ß1.

Immobilization of penicillin G acylase on oxirane-modified mesoporous silicas.

Experimental adsorption kinetics and equilibrium results of penicillin G acylase (PGA, from Escherichia coli, EC 3.5.1.11) on mesoporous silicas with pore sizes ranging from 5.6 to 33.2 nm showed that samples with pore sizes between 11.0 and 13.2 nm exhibited the best performance in immobilizing PGA under mild experimental conditions. A mesoporous silica sample with an optimum pore size of about 11.5 nm was then modified with different amounts of glycidoxypropyltrimethoxysilane to yield oxirane-functionalized silicas of different densities of surface oxirane groups. Under very mild incubation conditions, a partially oxirane-functionalized silica sample was found to be more efficient in immobilizing PGA than a fully oxirane-functionalized sample and a commercial polymer carrier (i.e., Eupergit C). With the partially oxirane-functionalized mesoporous silica sample as a carrier, a PGA loading of 110 mg/g (dry support) and an enzymatic activity of as high as 3477 unit/g (dry support) were achieved within 24 h of incubation. The residual surface silanol groups on the partially oxirane-functionalized silica were observed to play a pivotal role in facilitating the covalent binding of PGA with the oxirane groups at low salt concentrations.

Synthesis of large-pore methylene-bridged periodic mesoporous organosilicas and its implications.

In this article, we report the synthesis of methylene-bridged periodic mesoporous organosilicas (PMOs) of the SBA-15 type. The materials were characterized by SAXS, BET, NMR, FESEM, and TEM. It was found that the synthesis of methylene-bridged SBA-15 PMOs requires more rigorous conditions than that of SBA-15 PMOs bearing organic bridges other than methylene. A mild acidic environment, which slows down the hydrolysis and condensation rates of the precursor, with the assistance of a salt, which enhances precursor-template interaction, should be used to synthesize high-quality large-pore methylene-bridged PMOs. We attributed this to the fast hydrolysis and condensation rates and the rigid backbone of precursor 1,2-bis(triethoxysilyl)methylene. By examining and comparing the synthesis of three large-pore PMOs with different bridges, we concluded that the inductive, bridging, and conformation effects of the organic bridging group play an important role in the synthesis of large-pore PMO materials.

Morphologies of large-pore periodic mesoporous organosilicas.

In this article, we report a systematic investigation on the morphologies of SBA-15 type large-pore periodic mesoporous organosilicas templated by the block copolymer P123. By tuning synthetic parameters such as stirring, acidity, reaction ratio, reaction duration, and autoclaving, a wide spectrum of unique primary particle morphologies, such as the spindle-, pearl-, diamond-, rod-, and platelike particles, and nanoparticles has been prepared. These primary particles were found to self-assemble in solution to form various large hierarchical macrostructures, such as mesostructured necklaces and cobweb-supported necklaces. The assembling process was elucidated with the information observed at different stages of reaction. Stirring, reaction duration, and autoclaving were identified to be the key factors affecting the efficiency and degree of the self-assembly process. A nucleation-accretion mechanism for the formation of various PMO primary particles was proposed by examining the relation between the external morphologies and the underlying mesostructure.