The impact of applying natural clinoptilolite (zeolite) on the chemical,sensory and microbiological changes of vacuum packed sardine fillets

Different doses (1% and 5%) of natural zeolite were applied to determine quality changes in vacuum packaged sardine fillets during 19 days at 4 ± 1 °C. Zeolite had an effect to improve sensory quality of sardine especially for removing off‐odour. The acceptable shelf life of vacuum packaged sardine was 8 days for control and 12 days for groups treated with 1% and 5% zeolite. The zeolite application resulted in significant reduction in total volatile basic nitrogen values, except for group treated with 5% zeolite at 15 days. Although the effect of zeolite depended on dose and specific storage days, application of zeolite had no effect on free fatty acid analysis. The use of zeolite significantly reduced ammonia and biogenic amine accumulation, especially for histamine and tyramine. The result of the study showed that the efficacy of zeolite as natural antimicrobials was high and lower dose of zeolite has to be applied to get maximum preservation effect.     

Experimental Investigation of Aluminum Alloy and Steel Core Buckling Restrained Braces (BRBs)

International Journal of Steel Structures - Buckling restrained braces (BRBs) display balanced hysteretic behavior under reversed cyclic tension and compression forces and dissipate a significant...     

The Effect of Different Polishing Sequences on the Adhesion of Streptococcus mutans to Feldspathic Porcelain

The aim of this research was to determine whether extra-oral surface treatments on feldspathic porcelain surfaces influence initial adhesion of Streptococcus mutans. Ninety-six porcelain specimen discs were fabricated and divided into six equal groups according to surface treatment: fine-grit diamond polishing (Group 1); self-glazing (Group 2); overglazing (Group 3); overglazing followed by a finishing procedure and then overglazing (Group 4); Pearl Surface polishing (Group 5); and Diamond Twist SCL^TM polishing (Group 6). Surface roughness and hydrophobicity were assessed. An S. mutans suspension was incubated on each specimen group and evaluated. A one-way analysis of variance, post-hoc Tukey honestly significantly different test, Friedman test, and t-test were used for statistical analysis. Group 1 showed the highest surface roughness (p < 0.001) and bacterial adhesion (p < 0.05). Groups 5 and 6 specimen surfaces presented significantly higher contact angles (p < 0.05). Group 1 had the highest S. mutans adhesion, followed by Groups 3, 5, 6, 2, and 4 (p < 0.05). Reglazing after grinding may therefore decrease bacterial adhesion beneficially.     

Reuse of glass waste in the manufacture of ceramic tableware glazes

Today, various studies are carried out to spread the understanding of sustainability. The sustainability of production processes gains importance in corporate areas. In this study, the use of glass waste instead of frit used in glaze compositions in the ceramic industry was evaluated. The chemical and physical properties of glass wastes on samples were examined. The glaze formulations were prepared using 3%, 5%, and 8% by weight of glass waste instead of frit. Glass wastes were added to glaze compositions and 12 different glaze formulation studies were carried out. Transparent, Opaque, and Matte test glazes were prepared with glass waste added glaze formulations, and these glazes were applied to ceramic bodies. SEM (scanning electron microscope) analysis of standard glaze and glass waste added glazes was performed to determine the microstructural and morphological characterizations. Also, surface whiteness, brightness, L*a*b values, glaze flows, harcort test results, and final water absorption values were compared. As a result of the studies, it has been determined that it is appropriate to use 3% glass waste by weight instead of the frit in the production of ceramic tableware.     

Modification of polycaprolactone-styrene-vinyl trimethoxysilane terpolymer with sunflower oil for coating purposes

Polycaprolactone-styrene-vinyl trimethoxysilane terpolymer was prepared and then modified with sunflower oil partial glyceride (SFOPG) via a sol–gel method for use as a binder in coating applications. Therefore, a vinyl-functionalized polyester-based macromonomer (HPCL) was prepared via ring-opening polymerization of ?-caprolactone (CL) using 2-hydroxyethyl methacrylate (HEMA) followed by copolymerization with styrene (St) and vinyl trimethoxysilane (VTMS) to yield a terpolymer (HPCL-St-VTMS). The terpolymer was characterized by FTIR, GPC and ¹H NMR. To overcome the fact that the cured film of HPCL-St-VTMS was slightly soft, SFOPG was used as a modifier and was inserted to the structure via a sol–gel reaction between the hydroxyl groups and methoxy silane moieties of the terpolymer. After this modification, the softness disappeared. Nanosize inorganic domains were observed in the SEM image. Thermal analyses of the resulting cross-linked film of SFOM-HPCL-St-VTMS were performed with DSC and TGA. SFOM-HPCL-St-VTMS, which does not melt, resulted in a higher char yield and decomposition temperature at 5% weight loss compared to the unmodified HPCL-St-VTMS film. An evaluation of the film properties indicated that SFOM-HPCL-St-VTMS can be used as a coating material.     

Adsorption kinetics of malachite green onto activated carbon prepared from Tunçbilek lignite

Adsorbent (T₃K618) has been prepared from Tunçbilek lignite by chemical activation with KOH. Pore properties of the activated carbon such as BET surface area, pore volume, pore size distribution, and pore diameter were characterized by t-plot based on N₂ adsorption isotherm. The N₂ adsorption isotherm of malachite green on T₃K618 is type I. The BET surface area of the adsorbent which was primarily contributed by micropores was determined 1000 m²/g. T₃K618 was used to adsorb malachite green (MG) from an aqueous solution in a batch reactor. The effects of initial dye concentration, agitation time, initial pH and adsorption temperature have been studied. It was also found that the adsorption isotherm followed both Freundlich and Dubinin–Radushkevich models. However, the Freundlich gave a better fit to all adsorption isotherms than the Dubinin–Radushkevich. The kinetics of adsorption of MG has been tested using pseudo-first-order, pseudo-second-order and intraparticle diffusion models. Results show that the adsorption of MG from aqueous solution onto micropores T₃K618 proceeds according to the pseudo-second-order model. The intraparticle diffusion of MG molecules within the carbon particles was identified to be the rate-limiting step. The adsorption of the MG was endothermic (ΔH° = 6.55–62.37 kJ/mol) and was accompanied by an increase in entropy (ΔS° = 74–223 J/mol K) and a decrease in mean value of Gibbs energy (ΔG° = −6.48 to −10.32 kJ/mol) in the temperature range of 20–50 °C.     

Backpressure scheduling in IEEE 802.11 wireless mesh networks: Gap between theory and practice

Achieving efficient bandwidth utilization in wireless networks requires solving two important problems: (1) which packets to send (i.e., packet scheduling) and (2) which links to concurrently activate (i.e., link scheduling). To address these scheduling problems, many algorithms have been proposed and their throughput optimality and stability are proven in theory. One of the most well-known scheduling algorithms is backpressure scheduling which performs both link and packet scheduling assuming a TDMA (Time Division Multiple Access) MAC (Medium Access Control) layer. However, there has been limited work on realizing backpressure scheduling with a CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) MAC layer (e.g., IEEE 802.11). In IEEE 802.11 networks, it is expected that the throughput optimality will not be achieved. In this paper, we investigate the extent of this throughput gap between theoretical TDMA-based backpressure scheduling and an approximation of it for IEEE 802.11 WMNs (Wireless Mesh Networks). Through extensive testbed measurements, we verify that there is indeed a non-negligible throughput gap. We present two main reasons behind this gap: Control inaccuracy that results from approximation of link scheduling and information inaccuracy that results from late or incorrect information, for instance, about queue lengths or network topology. Our results show that losses by MAC-layer collisions and backoff, which mainly occur due to control inaccuracy plays a major role for the throughput gap. On the other hand, while losses by queue drops, typically due to information inaccuracy, do occur, their effect can be tolerated. Nevertheless, both types of inaccuracies need to be mitigated in order to improve throughput.     

Can we restore the colour of long-term discoloured resin composites by noninvasive methods?

The aim of this study is to investigate the effect of toothbrushing and paste repolishing on the colour restitution of long-term coffee discoloured prefabricated and direct resin composites. One prefabricated (Componeer-Coltène) and three direct resin composites (Brilliant Ever Glow-Coltène, Essentia-GC, Harmonize-Kerr) were tested. Componeer samples were prepared with and without polishing while the other groups were all polished. After baseline colour-measurement, the specimens were immersed in coffee for 3-month and colour-measurement was repeated, then a simulation of 1-year of toothbrushing (Toothbrush Simulation ZM-3.4-SD Mechatronics) with Pro-Expert Professional Protection-Ipana, 3D White Luxe Perfection-Ipana, and White Ruscello-GC toothpaste was performed. Colour-changes (ΔE) after toothbrushing and repolishing with polishing paste (Enamelize, Cosmodent) were calculated. The discolouration occurred after prolonged exposure to a coffee solution was above the clinically acceptable level of ΔE = 2 in all groups, except Componeer polished group. The lowest discoloured group was Componeer polished (ΔE = 1.66 ± 0.32) while the highest was Essentia group (ΔE = 4.30 ± 0.48). The samples toothbrushed with White Ruscello exhibited the greatest colour restitution (ΔE = 2.06 ± 0.75) (P < .05). After paste repolishing, slight colour restitution was observed among all the groups, but the differences between them remained the same as after the toothbrushing procedure. Prolonged exposure to coffee solution affects the colour of the resin composites and noninvasive methods can provide colour restitution below the critical value for visual perception (ΔE = 3.3). Noninvasive procedures such as toothbrushing with a whitening toothpaste or repolishing with a polishing paste may ensure the colour restitution of direct resin composite restorations until a clinically acceptable level.