A water-soluble Irgacure 2959-based diallylammonium salt system for antibacterial coatings

A water-soluble mixture of a novel diallylammonium salt photoinitiator based on 2-hydroxy-1-[4-(2-hydroxyethoxy) phenyl]-2-methyl-1-propanone (Irgacure 2959 or I2959) and diallylammonium tosylate has been prepared. It shows excellent water-solubility of 6.8 wt% in water, much greater than the solubility of I2959 (<2 wt%). It has a strong absorbance at 269 nm (ε ~ 15731) in methanol. It exhibits 15.6 times higher migration stability than I2959 due to its monomeric nature. Its photoinitiating efficiency of 2-hydroxyethylmethacrylate (HEMA) and poly(ethylene glycol) diacrylate (PEGDA, M_n = 575 D) was found to be similar to I2959. PEGDA hydrogels prepared using the synthesized photoinitiator (PI) were found to have highly porous structures (15.44 μm) compared with those using I2959. PEGDA film prepared using this PI has demonstrated antibacterial properties against gram-negative Pseudomonas aeruginosa (ATCC 15442) and gram-positive Staphylococcus aureus (ATCC 23235) bacterial species.     

Performance comparisons of the image quality evaluation techniques in Wireless Multimedia Sensor Networks

Recent developments with the integration of new vision capabilities into the wireless sensor devices have resulted in the necessity of investigating the behavior of well known image quality evaluation techniques in Wireless Multimedia Sensor Networks (WMSN). Wireless sensor devices can collect process and evaluate image data with a camera module. These devices can also monitor the image quality in order to take some adaptive precautions at the communications layer protocols and thus guarantee application layer quality requirements. In order to evaluate the transmitted image quality results more accurately, it’s imperative to analyze the factors which lead to change in behaviors of existing image quality evaluation techniques. In this work, the effect of the transmission distortions, packet size, link and node correlation on the image quality evaluation are highlighted. The success of prevalent image quality metrics is also examined with emphasis on whether these metrics can reflect implicitly the region of interest (ROI) information in an image. Furthermore, a simple metric is proposed to estimate an image quality on the fly by considering the ROI parts of the image and using only the average of the packets and their priority level. This study leads to explore smart ways for the adaptation of the communication protocols to the wireless environment.     

Effect of root canal sealers on the push-out bond strengths of tooth-colored posts to root dentine

Objectives: This study evaluated the effect of different root canal sealers on the push-out bond strength of tooth-colored posts to root dentin. Material and methods: Eighty human mandibular premolar teeth with single roots were decoronated and randomly divided into two groups according to post material: G1–G5: Cytec blanco; G6–G10: Cosmopost. In each group, the specimens were further subgrouped according to the filling material plus sealer (n = 8): G1, G6: Gutta-percha + AH Plus; G2, G7: Resilon + Epiphany SE; G3, G8: Gutta-percha + Sealite; G4, G9: Gutta-percha + iRoot SP; and G5, G10: control (unobturated). Cytec blanco and Cosmopost of 1.4 mm diameter were adhesively luted to samples using Variolink II. Push-out test was performed in a universal testing machine, and failure modes were examined under stereomicroscope. Data were analyzed with the two-way ANOVA and post hoc Tukey’s tests. Statistical significance was set to 0.05. Results: Roots obturated with AH Plus (3.48 ± 1.41 MPa), Sealite (3.47 ± 0.65 MPa), and Resilon (3.36 ± 1.23 MPa) had the lowest bond strength (p < 0.005). iRoot SP and control group samples showed the highest bond strength values (7.38 ± 0.89 MPa and 6.43 ± 1.16 MPa, respectively) (p < 0.05). Significant differences were observed among tooth-colored posts and sealers (p < 0.05). Adhesive failures were predominant in all groups (48%). Conclusions: When the resin cement Variolink II was used, the types of root canal filling materials and sealers could affect the retentions of the fiber/zirconium posts; the fiber post revealed the higher bond values than the zirconium post; and the calcium silicate-based sealer (iRoot SP) revealed the highest bond strengths.     

Evaluation of Nitrite in Ready-Made Soups

As time is very important for today’s people, ready-made soups in different forms (powder, liquid, canned) are consumed highly. Nitrite has been implicated with a variety of long-term adverse effects and has been of interest to public health providers and governmental regulators for the last 40 years. The present study was aimed to assess nitrite levels in commercially available soups in powder form by using a spectrophotometric method and to evaluate the possible toxicological outcomes. For this purpose, 66 ready-made soups were randomly collected and divided into seven groups: tomato-, chicken-, yoghurt-, mushroom-, lentil-, meat-, and vegetable-based. The minimum–maximum and median levels of nitrite content of the soup groups are 28–2,091 (median, 108), 53–400 (median, 136), 26–129 (median, 47), 58–197 (median, 109), 12–225 (median, 38), 12–555 (median, 40), 184–1229 (median, 389) mg kg⁻¹, respectively. Meat- and tomato-based soups have the highest nitrite contamination among the groups. On the other hand, acceptable daily intake (ADI) of nitrite given by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) and Scientific Committee on Food (SCF) is 0–0.07 mg kg⁻¹ (body weight, b.w.) per day, while Environmental Protection Agency (EPA) has set a reference dose (R_fD) of 0.10 mg nitrite nitrogen per kilogram b.w. per day (equivalent to 0.33 mg nitrite ion per kilogram b.w. per day). This means that the highest intake of nitrite a 70-kg person must be no more than 4.9 mg in 1 day according to JECFA and SCF and 7 mg kg⁻¹ b.w. per day according to EPA. However, nitrite intake from one portion (13 g) meat-based soups, when calculated with median daily intake levels (5.05 mg), exceeds the limit of JECFA and SCF. With long-term daily consumption of high nitrite levels exceeding ADI, the risk of mild to moderate methemoglobinemia would be increased, especially for susceptible populations such as young children and elderly. Besides, the higher intake of nitrite from foodstuff and other sources may induce the formation of carcinogenic nitrosamines which are formed endogenously from nitrites and nitrates. The first results of the study were presented as a poster at the 121st AOAC Annual Meeting & Exposition, held at Anaheim, California USA, September 16–20, 2007.     

Demonstrating feasibility of a high temperature polymer electrolyte membrane fuel cell operation with natural gas reformate composition

Experimental data on the performance of a single cell PBI-based HT-PEMFC operated with a fuel composition similar to natural gas reformate and oxygen enriched cathode air are presented. A test studying the effect of CO₂, H₂O and CO in the fuel on fuel cell performance revealed that the presence of CO₂ mainly worsens mass transport, H₂O improves proton conduction and CO influences reaction kinetics as well as causing mass transport limitations. A small increase of the O₂ concentration in the oxidant provided a boost on performance. Electrical efficiency of the fuel cell was improved from 36.6% with H₂/air operation up to 38.2% with synthetic reformate gas/30% O₂ enriched air. Three 1000 h long-term tests at constant load conditions were performed. The first test showed a degradation rate of ?21.4 μV/h and was operated with H₂/30% O₂. The second test was performed with the same kind of MEA but different fuel composition (54% H₂, 15% CO₂ and 31% H₂O) and exhibited a reduction of the degradation rate to ?5.5 μV/h. The main reason for this lifetime improvement is H₂O because its transport from anode to cathode may sweep along PA that soaks catalyst active sites and limits HOR. Moreover, water in rich H₂ reformate streams also relieves formation of CO from CO₂ via RWGS. The third test was performed with a different kind of MEA (extra PTFE content in GDE) but the same fuel composition than the second one. A higher degradation rate of ?22.2 μV/h was observed but it was mainly caused by unprotected shut-downs during operation. Two preliminary long-term tests were also performed with a fuel composition similar to natural gas reformate (54% H₂, 14% CO₂, 1% CO and 31% H₂O). These latest tests revealed that the fuel cell should be operated at higher temperatures to diminish CO catalyst coverage, and that anode purge with dry gases avoids water condensation in gas pipes. In addition, CO poisoning on anode catalyst is time dependent and operation at high current densities enhances CO catalyst coverage.     

Effects of using combined essential oils on quality parameters of bio‐yogurt

Present study aims to develop a new type of probiotic yogurt with ginger and chamomile essential oils (EOs) at therapeutic levels (0.2 and 0.4%) by evaluating its some physical, chemical, microbiological and sensory characteristics. Probiotic types of yogurt samples and those with 0.4% ginger EO gave the largest counts of viable probiotic bacteria in the rates of 8.32 cfu/g and 8.01 cfu/g, respectively. It gave larger syneresis rate (8.64 mL/25 g) on the first day than the rest of the samples while C1 (only probiotic strain with direct vat set starter culture) sample represented the lowest rate (5.9 mL/25 g) on day 21. Among the samples with various contents, C2 (inoculated probiotic strain with 0.2% essential oil ginger) and C3 (inoculated probiotic strain with 0.4% essential oil ginger) were found to be organoleptically the most acceptable with close scores to that of control.

Practical applications

Antibacterial and antioxidant activities of essential oils have received considerable attention in food preservation. During bio‐yogurt storage, the edible film incorporating ginger and chamomile essential oils showed reducing effect on the microbial growth and extended the shelf‐life of samples.     

An optimization algorithm for a capacitated vehicle routing problem with time windows

In this paper, vehicle routing problem (VRP) with time windows and real world constraints are considered as a real-world application on google maps. Also, tabu search is used and Hopfield neural networks is utilized. Basic constraints consist of customer demands, time windows, vehicle speed, vehicle capacity and working hours. Recently, cost and on-time delivery are the most important factors in logistics. Thus, the logistic applications attract attention of companies. In logistic management, determining the locations of delivery points and deciding the path are the vital components that should be considered. Deciding the paths of vehicles provides companies to use their vehicles efficiently. And with utilizing optimized paths, big amounts of cost and time savings will be gained. The main aim of the work is providing the best path according to the needs of the customers, minimizing the costs with utilizing the VRP and presenting an application for companies that need logistic management. To compare the results, simulated annealing is used on special scenarios. And t-test is performed in the study for the visited path in km with p-value of 0.05.     

Does Internet use reflect your personality? Relationship between Eysenck’s personality dimensions and Internet use

The aim of this study was to investigate the relationship between three Eysenckian personality dimensions – psychoticism, extroversion and neuroticism – and the Internet use. A sample of 427 Turkish university students completed the Eysenck’s Personality Questionnaire, an Internet survey which contained questions about interpersonal motives for Internet use and a scale for measuring the tendency for expressing one’s “true” self on the Internet. The results indicated that psychoticism was the only personality dimension related to establishing new relationships and having “Internet only” friends; and extroversion was the only personality dimension that is related to maintaining long-distance relationships, and supporting daily face-to-face relationships. The results supported the idea that for some individuals, Internet can be used as social substitute for face-to-face social interactions while for some others it can be used as a tool of social extension, depending on the user’s personality characteristics. Also, psychoticism and neuroticism were found to be positively associated with the expressing “true self” on the Internet, and it was shown that the relationship between psychoticism and Internet uses as social substitute is mediated by the tendency to express one’s true self on the Internet.     

Computing minimum distortion embeddings into a path for bipartite permutation graphs and threshold graphs

The problem of computing minimum distortion embeddings of a given graph into a line (path) was introduced in 2004 and has quickly attracted significant attention with subsequent results appearing at recent stoc and soda conferences. So far, all such results concern approximation algorithms or exponential-time exact algorithms. We give the first polynomial-time algorithms for computing minimum distortion embeddings of graphs into a path when the input graphs belong to specific graph classes. In particular, we solve this problem in polynomial time for bipartite permutation graphs and threshold graphs. For both graph classes, the distortion can be arbitrarily large. The graphs that we consider are unweighted.