A mixed integer programming model for a closed-loop supply-chain network

In this paper, a new mixed integer mathematical model for a closed-loop supply-chain network that includes both forward and reverse flows with multi-periods and multi-parts is proposed. The proposed model guarantees the optimal values of transportation amounts of manufactured and disassembled products in a closed-loop supply chain while determining the location of plants and retailers. Finally, computational results are presented for a number of scenarios to show and validate the applicability of the model.     

Microwave assisted green chemistry approach of sodium metaborate dihydrate (NaBO2·2H2O) synthesis and use as raw material for sodium borohydride (NaBH4) thermochemical production

In the present study, a novel microwave assisted method has been developed for sodium metaborate dihydrate (NaBO₂·2H₂O) synthesis. Anhydrous NaBO₂, a derivative of borax, is an industrially and technologically important boron compound used as a raw material for the thermochemical production of sodium borohydride (NaBH₄). The effects of different microwave treatment conditions such as microwave power (90, 270 and 360 W) and irradiation time (1, 2, and 5 min) on the synthesis of NaBO₂·2H₂O were examined. After microwave irradiation at 270 W for 1 min, NaBO₂ crystals with 2 molar equivalents of water were formed. Anhydrous NaBO₂ was obtained following incubation at 400 °C for 33 min under calcination conditions. Then the resulting anhydrous NaBO₂ powder was reacted with MgH₂ under 60 bar hydrogen atmosphere at 470 °C, leading to successful production of NaBH₄ with 93% yield.     

The tricriteria flowshop scheduling problem

Multicriteria flowshop scheduling problems have been one of the most attractive subjects in recent years. In the multicriteria flowshop scheduling literature, a very limited number of studies have been performed on problems which include a tardiness criterion. In this paper a multicriteria (tricriteria) two-machine flowshop scheduling problem with a tardiness criterion is tackled. The objective is to minimise a weighted sum of total completion time, total tardiness and makespan. An integer programming model is proposed for the problem which belongs to NP-hard class. The modified NEH (Nawaz, Enscore and Ham) algorithm, a tabu search-based heuristic method, random search and the EDD rule (the earliest due date rule) are used to solve problems with up to 2,500 jobs. A computational analysis is conducted to evaluate the performance of the heuristics. The analysis shows that the heuristics are quite efficient, and the performance of the tabu search based heuristic is the best of all in terms of solution quality.     

Oxidative DNA damage correlates with carotid artery atherosclerosis in hemodialysis patients

Oxidative stress is accepted as a nonclassical cardiovascular risk factor in chronic renal failure patients. The aim of this study was to evaluate the relation between oxidative DNA damage (8‐hydroxy‐2′‐deoxyguanosine/deoxyguanosine [8‐OHdG/dG] ratio), oxidative stress biomarkers, antioxidant enzymes, and carotid artery intima‐media thickness (CIMT) in hemodialysis (HD) patients. Forty chronic HD patients without known atherosclerotic disease and 48 age‐ and sex‐matched healthy individuals were included in the study. Plasma malondialdehyde (MDA) levels and 8‐OHdG/dG ratio were determined as oxidative stress markers. Superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities were measured as antioxidants. CIMT was assessed by carotid artery ultrasonography. 8‐OHdG/dG ratios and MDA levels were higher; SOD and GPx activities were lower in HD patients compared to controls. HD patients had significantly higher CIMT compared to controls (0.61 ± 0.08 vs. 0.42 ± 0.05, p < 0.001). There was a significant positive correlation between CIMT and 8‐OHdG/dG ratio (r = 0.57, p < 0.01) and MDA levels (r = 0.41, p < 0.01), while there was a significant negative correlation between CIMT and SOD (r = ?0.47, p < 0.01) and GPx levels (r = ?0.62, p < 0.01). It is firstly demonstrated that CIMT is positively correlated with oxidative DNA damage in HD patients without known atherosclerotic disease.     

Microleakage in class V cavities prepared using conventional method versus Er:YAG laser restored with glass ionomer cement or resin composite

This study evaluated the effect of tooth preparation method (diamond bur vs. Er:YAG laser) on the microleakage levels of glass ionomers and resin composite. Human permanent premolars (N = 80) were randomly divided into two groups (n = 40). Cavities on half of the teeth were prepared using diamond bur for enamel and carbide bur for dentin and the other half using Er:YAG laser. The teeth were randomly divided into four groups according to the restoration materials, namely (a) ChemFil Rock (CFR), (b) IonoluxAC (IAC), (c) EQUIA system (EQA) and one resin composite (d) AeliteLS (ALS) (n = 10 per group). Microleakage (μm) was assessed at the occlusal and gingival margins after dye penetration (0.5% basic fuchsine for 24 h). On the occlusal aspect, while the cavity preparation types significantly affected the microleakage for CFR (p = 0.015), IAC (p = 0.001) glass ionomer restorations, it did not show significant effect for glass ionomer EQA (p = 0.09) and resin composite ALS (p = 0.2). Er:YAG laser presented less microleakage compared to bur preparation in all groups except for EQA. On the gingival aspect, microleakage decreased significantly for CFR (p = 0.02), IAC (p = 0.001), except for EQA where significant increase was observed (p = 0.001) with the use of Er:YAG laser. Microleakage decrease was not significant at the gingival region between diamond bur and Er:YAG laser for ALS (p = 0.663). At the occlusal and gingival sites in all groups within each preparation method, microleakage level was not significant.     

Substitution of Reduction Clearing Step by Ozone Treatment at Disperse Dyeing of Polyester

The effectiveness of ozone treatment for the afterclearing of disperse dyed poly (ethylene terephthalate) (PET) fibers has been examined. Two types of disperse dyed PET samples were selected among commercial mass production range of Akbaslar textile mill. The reduction clearing procedure applied during mass production was taken as the reference reduction clearing treatment; these reference samples were taken after dyeing and reduction clearing processes at the mill. Samples of disperse dyed PET were also taken before reduction clearing in order apply ozone treatment in the laboratory as the tested afterclearing method. Color and wash-fastness properties of the reduction cleared and ozone treated fabric samples were compared and reported. Results indicated acceptable color and wash-fastness results comparable to those of reduction cleared samples for ozone treated samples. The success of ozone treatment for the black dyed PET sample at 7.0% depth of shade was especially outstanding. Ozone treatment was applied in cold water without addition of any chemicals for very short treatment times when compared to conventional reduction clearing. Ozone treatment created substantial energy and chemical savings as well as lower environmental impact.     

Ultrahigh Efficiency Fluorescent Single and Bi‐Layer Organic Light Emitting Diodes: The Key Role of Triplet Fusion

A new family of anthracene core, highly fluorescent emitters is synthesized which include diphenylamine hole transport end groups. Using a very simple one or two layer organic light emitting diode (OLED) structure, devices without outcoupling achieve an external quantum efficiency of 6% and photonic efficiencies of 20 cd/A. The theoretical maximum efficiency of such devices should not exceed 3.55%. Detailed photophysical characterization shows that for these anthracene based emitters 2T₁≤T_n and so in this special case, triplet fusion can achieve a singlet production yield of 0.5. Indeed, delayed electroluminescence measurements show that triplet fusion contributes 59% of all singlets produced in these devices. This demonstrates that when triplet fusion becomes very efficient, fluorescent OLEDs even with very simple structures can approach an internal singlet production yield close to the theoretical absolute maximum of 62.5% and rival phosphorescent‐based OLEDs with the added advantage of much improved stability.     

Ultrasound‐assisted bioscouring of cotton

In this study, the effects of ultrasound on the bioscouring of cotton by alkaline pectinase were examined. Conventional alkaline scouring was considered as the control treatment, and two different sources of ultrasound, an ultrasonic bath and an ultrasonic homogeniser, were tested, along with the enzymatic scouring process. Results indicated a clear increase in the efficiency of the enzymatic scouring process when the ultrasonic homogeniser was used: wettability time and wicking distance after ultrasonic homogeniser‐assisted bioscouring were much better than for enzymatic scouring without the use of ultrasound energy and almost the same as when conventional alkaline scouring was employed. Ultrasonic bath‐assisted enzymatic bioscouring gave slightly better results than enzymatic scouring without sonication. Reasons for the difference in efficacy of the ultrasound sources were postulated. Weight loss was increased by the use of ultrasonic equipment during enzymatic scouring. Fabric thickness and fabric strength was not significantly affected by the scouring processes. The environmental impact of the processes was also monitored by chemical oxygen demand measurement of the treatment liquors. Conventional alkaline scouring resulted in the highest environmental impact. Ultrasonic homogeniser‐assisted bioscouring also led to slightly higher chemical oxygen demand loads than other enzymatic processes owing to the more efficient removal of impurities.     

Effect on response time and diffraction efficiency of co-usage azo dye and carbon nanoparticle in nematic liquid crystal

In this work, the formation of the photo-induced grating and nonlinear optical properties such as diffraction efficiency (η), refractive index modulation (Δn), nonlinear index coefficient (n₂) of nematic liquid crystal (E7) doped by azo dye (Methyl Red) and C60 have been investigated by diffraction grating measurements. Diffraction efficiencies of 441 nm pump and 632 nm probe beams were measured in two-wave mixing experiment. Maximum diffraction efficiency was found 26% doped with both 1% MR and 0.5% C60, while cells without C60 had maximum diffraction efficiency of 19% under 30 mW laser illumination. Rise time was found to increase with Methyl Red concentration. The nonlinear index coefficient, n₂, was calculated to be 11 × 10⁻³ cm²/W and highly depend on MR concentration.     

Effect of fuel type on the optimum thickness of selected insulation materials for the four different climatic regions of Turkey

The optimum insulation thickness of the external wall for four various cities from four climate zones of Turkey, energy savings over a lifetime of 10 years and payback periods are calculated for the five different energy types and four different insulation materials. Foamboard 3500, Foamboard 1500, extruded polystyrene and fiberglass as insulation material are selected. In this study, it is calculated the value of the amount of the net energy savings using the P₁–P₂ method. The results show that optimum insulation thicknesses vary between 1.06 and 7.64 cm, energy savings vary between 19 $/m² and 47 $/m², and payback periods vary between 1.8 and 3.7 years depending on the city and the type of fuel. The highest value of energy savings is reached in A?r? for LPG fuel type, while the lowest value is obtained in Ayd?n for natural gas.