Supply Chain Network Designs Developed for Deteriorating Items Under Conditions of Trade Credit and Partial Backordering

Deteriorating items, trade credit, and partial backordering are common in today’s business. However, no previous study on supply chain network design has considered these business aspects together. In this paper, we present supply chain networks designed for deteriorating items under trade credit and two conditions: (a) no shortage and (b) partial backordering of goods. We also present 2 algorithms based on nonlinear optimization that were developed in order to optimize the influence area and the joint replenishment-cycle time in the no-shortage case, and to identify the optimal shortage level in the partial-backordering case. The numerical examples presented herein illustrate how the solution procedure works. The effects of various values of the tested parameters on decisions and costs are also discussed. Our results could be used as a reference by managers when making business decisions.     

Characteristics of Pleurotus sp. TD36 and its ability to reduce wood extractives in pretreatment for pulping

Lipophilic extractives of wood cause pitch deposition during pulp and paper production, leading to serious economic losses and environmental pollution. Natural seasoning of wood material before pulping can reduce wood extractives, but there is no control of the pulp yield and quality. Pretreatment of the wood chips with selected fungi is regarded as better controlled seasoning with effective removal of problematic extractives. Commercially available fungal preparations are effective mostly for softwood, but not quite suitable for Acacia mangium and hybrid hardwood—the main pulpwood of Vietnam. In this paper, a fungal isolate TD36 was identified as white-rot basidiomycete Pleurotus sp. TD36 based on the biological characteristics and phylogenetic analysis. Having high activity of ligninolytic enzymes, amylase and protease, Pleurotus sp. TD36 was able to degrade lignin-like compounds (guaiacol, Remazol Brilliant Blue), starch and casein. Degradation of wood extractives was evaluated by laccase and sterol esterase assays of the fungus in shake flask cultures and in pretreatment of Acacia wood chips. Favorable conditions for wood pretreatment were selected, including: inoculum size, 1% v/w; wood moisture, 60% v/w; temperature, 28–30 °C and 30 days. Under such conditions, Pleurotus sp. TD36 removed about 68?±?2.75% of wood acetone extractives soluble in chloroform. Of that, about 73–89% of fatty acids and fatty alcohols, 76% of free sterols and 63% of sterol ester, were removed. Fungal pretreatment did not significantly affect the cellulose content of wood and Kraft pulp yield.

     

Optimizing reverse logistic costs for recycling end-of-life electrical and electronic products

With accelerating technological changes and market expansions of electrical and electronic products (EEPs) during the last few decades, much focus and effort have been placed on the waste of these products. In order to reduce their negative impacts on the environment and human, at the end of their product lifecycles, their wastes need to be properly handled, processed, disposed, and if applicable, remanufactured, recycled or reused. Based on the analysis of the waste EEPs (WEEPs) reverse logistic network, this paper presents a mathematical programming model which minimizes the total processing cost of multiple types of WEEPs. The monetary factors considered in the model include the costs of collection, treatment, and transportation as well as sales income with different fractions of returned products. Based on the proposed model, the optimal facility locations and the material flows in the reverse logistic network can be determined. A sensitivity analysis of the proposed model is also presented. Finally, a numerical example is illustrated to gain a better insight into the proposed model.     

Crystal Structures of a Bioactive 6′‐Hydroxy Variant of Sisomicin Bound to the Bacterial and Protozoal Ribosomal Decoding Sites

Parasitic infections recognized as neglected tropical diseases are a source of concern for several regions of the world. Aminoglycosides are potent antimicrobial agents that have been extensively studied by biochemical and structural studies in prokaryotes. However, the molecular mechanism of their potential antiprotozoal activity is less well understood. In the present study, we have examined the in vitro inhibitory activities of some aminoglycosides with a 6′‐hydroxy group on ring I and highlight that one of them, 6′‐hydroxysisomicin, exhibits promising activity against a broad range of protozoan parasites. Furthermore, we have conducted X‐ray analyses of 6′‐hydroxysisomicin bound to the target ribosomal RNA A‐sites in order to understand the mechanisms of both its antibacterial and antiprotozoal activities at the molecular level. The unsaturated ring I of 6′‐hydroxysisomicin can directly stack on G1491, which is highly conserved in bacterial and protozoal species, through π–π interaction and fits closer to the guanidine base than the typically saturated and hydroxylated ring I of other structurally related aminoglycosides. Consequently, the compound adopts a lower energy conformation within the bacterial and protozoal A‐sites and makes pseudo pairs to either A or G at position 1408. The A‐site‐selective binding mode strongly suggests that 6′‐hydroxysisomicin is a potential lead for the design of next‐generation aminoglycosides targeting a wide variety of infectious diseases.     

Beryllium Ion Implantation into GaAs and Pseudomorphic AIGaAs/lnGaAs/GaAs Heterostructure

Implantations of Be, Be + P, Be + F, Be + P +F, BeF and Mg + P into GaAs and AlGaAs/InGaAs/GaAs pseudomorphic heterostructure were evaluated by secondary ion mass spectrometry profilings and electrical resistivity measurements. Rapid thermal annealing causes a strong diffusion of Be when implanted alone. Co-implantation with P prevents both diffusion and degradation of the Gaussian-shape implant distribution and thus improves the semiconductor sheet resistivity. Annealing at 850°C for 10 s for a Be + P co-implant results in a 60% activation efficiency, and lower diffusion and resistivity when compared to single Be, Be + F, Be + F + P, BeF, and Mg + P implanted at the same dose.     

Neuro-fuzzy TSK network for calibration of semiconductor sensor array for gas measurements

The neuro-fuzzy network applying Takagi-Sugeno-Kang (TSK) fuzzy reasoning for the calibration of the semiconductor sensor array is developed in this paper. The structure, as well as the learning algorithm of the neuro-fuzzy network, is presented and tested on the example of estimation of the concentration of gas components in the gaseous mixture (so-called artificial nose problem). The results of numerical experiments are presented and discussed.     

Effects of solvents on characteristics of crystalline lactose extracted in ternary and quaternary systems

In a technique referred to as lactose extractive crystallisation, a volatile solvent was added to a solution of lactose dissolved in water. As this second solvent was miscible in water, its presence in the saturated or supersaturated lactose solution would reduce the lactose solubility and hence lactose crystals were formed and grew in the ternary system lactose–ethanol–water. It was found that selecting ethanol as a second solvent could produce needle-shaped crystals having the lowest median size of 8 μm, and β-lactose content up to 60% at 60 °C. On the other hand, using two miscible solvents, one non-volatile and one volatile, such as by adding ethanol to the ternary system, lactose–water–glycerol, crystals having large needle-like or trapezoidal shape and β-lactose content up to 90% could be made at 70 °C. The triangle diagram comparing the solubility of lactose in the glycerol and ethanol aqueous solutions at equilibrium and at different temperatures is presented for the first time. Based on this diagram, it is suggested that the weight ratios of two solvents used and reaction temperatures could be manipulated to produce lactose crystals with different characteristic properties.     

Fabrication and in vitro evaluations with osteoblast-like MG-63 cells of porous hyaluronic acid-gelatin blend scaffold for bone tissue engineering applications

In this study, hyaluronic acid–gelatin (HyA–Gel) scaffolds were prepared with HyA:Gel ratios of 15:85, 50:50, and 85:15 with the goal of obtaining a porous biocompatible scaffold for bone tissue engineering applications. Scanning electron microscopy and Fourier-transform infrared spectroscopy were done to characterize the morphological orientations of the scaffolds. The biocomposite structure was highly porous and the pores in the scaffolds were interconnected. The compressive strength of the scaffold was 7.39 ± 0.2 MPa for the HyA–Gel when fabricated at a ratio of 15:85. To assess the biocompatibility and cell behavior on the HyA–Gel biocomposite, the proliferation of MG-63 osteoblast cell on the scaffolds was examined using the MTT assay, optical microscopy, and confocal microscopy. Collagen type I and osteopontin expression of cells cultured on the scaffolds were examined using immunoblotting. The scaffolds fabricated with a 15:85—HyA:Gel ratio showed excellent biocompatibility, good mechanical properties, and high porosity, which suggest that the highly porous scaffold holds great promise for use in bone tissue engineering applications.     

A dual criterion of equivalent linearization method for nonlinear systems subjected to random excitation

A dual criterion of equivalent linearization method is suggested. The mean-square responses of Duffing, Van der Pol and Lutes-Sarkani oscillators subjected to random excitation are considered. The obtained results are compared with the numerical calculations of original systems and approximate solutions obtained by three different methods including the conventional linearization technique, energy method and regulation linearization method. The results show that in those nonlinear systems the accuracy of the mean-square response is significantly improved by the proposed criterion.