Synthesis of polymer supported Ni (II)-Schiff Base complex and its usage as a catalyst in sodium borohydride hydrolysis

Influence of using as catalysis, Ni-Schiff Base complex which we previously synthesized [1] used to support with amberzyme oxirane resin (A.O.R.) polymer for increasing the catalytic activity in NaBH₄ hydrolysis reaction, to hydrogen generation was studied. The prepared catalyst was characterized by using SEM, XRD, BET, FT-IR analyze technique. Polymer supported Ni-Schiff Base complex catalyzed NaBH₄ hydrolysis reaction was investigated depending on concentration of NaBH₄, concentration of NaOH, temperature, percentage of Ni complex in total polymer supported Ni-Schiff Base complex and amount of catalyst factors. The maximum hydrogen production rate from hydrolysis of sodium borohydride with nickel-based complex catalyst compared to the pure nickel catalyst is increased from 772 mL H₂·g^?1 cat.·min^?1 to 2240 mL H₂ g^?1 cat.·min^?1 [1], and with supported amberzyme oxirane resin polymer this nickel based complex catalyst was increased to 13000 mL H₂·g^?1 cat.·min^?1 at 30 °C. The activation energy of complex catalyzed NaBH₄ hydrolysis reaction was found as 25.377 kJ/mol. This work also includes kinetic information for the hydrolysis of NaBH₄.     

Effect of heat treatment on the creep behavior of α/β SiAlON sintered with multication oxide sintering additives

SiAlONs are important materials for high-temperature applications and creep properties of SiAlONs are largely controlled by the amount and type of sintering additives. It has been established that heat treatment can reduce the amount of amorphous intergranular phase through crystallization. However, there is no study on the creep behavior of heat-treated SiAlON ceramics containing multication sintering additives. Therefore, the aim of the study was to investigate the effect of heat treatment on the creep properties of multication containing (Y-Sm-Ca oxides) α/β-SiAlON ceramics. The heat treatments of the sintered samples were carried out at 1600°C for 2 hours. The creep tests were carried out in the range 1300-1400°C under different loads (50-150 MPa). The existing phases and the microstructures of samples before and after creep were investigated using XRD and SEM techniques. It was found that heat treatment resulted in a better creep performance compared to as-sintered samples. The activation energy and stress exponent for heat-treated SiAlONs were also calculated as 708 ± 45 kJ/mol and 1.4, respectively. Compared to the sintered sample values, the results suggested that the acting creep mechanism of grain-boundary sliding and cavitation was reduced with the heat treatment.     

Evaluating Internet end-to-end performance: overview of test methodology and results

OBJECTIVE: An evaluation of Internet end-to-end performance was conducted for the purpose of better understanding the overall performance of Internet pathways typical of those used to access information in National Library of Medicine (NLM) databases and, by extension, other Internet-based biomedical information resources. DESIGN: The evaluation used a three-level test strategy: 1) user testing to collect empirical data on internet performance as perceived by users when accessing NLM Web-based databases, 2) technical testing to analyze the Internet paths between the NLM and the user's desktop computer terminal, and 3) technical testing between the NLM and the World Wide Web ("Web") server computer at the user's institution to help characterize the relative performance of Internet pathways. MEASUREMENTS: Time to download the front pages of NLM Web sites and conduct standardized searches of NLM databases, data transmission capacity between NLM and remote locations (known as the bulk transfer capacity [BTC]), "ping" round-trip time as an indication of the latency of the network pathways, and the network routing of the data transmissions (number and sequencing of hops). RESULTS: Based on 347 user tests spread over 16 locations, the median time per location to download the main NLM home page ranged from 2 to 59 seconds, and 1 to 24 seconds for the other NLM Web sites tested. The median time to conduct standardized searches and get search results ranged from 2 to 14 seconds for PubMed and 4 to 18 seconds for Internet Grateful Med. The overall problem rate was about 1 percent; that is, on the average, users experienced a problem once every 100 test measurements. The user terminal tests at five locations and Web host tests at 13 locations provided profiles of BTC, RTT, and network routing for both dial-up and fixed Internet connections. CONCLUSION: The evaluation framework provided a profile of typical Internet performance and insights into network performance and time-of-day/day-of-week variability. This profile should serve as a frame of reference to help identify and diagnose connectivity problems and should contribute to the evolving concept of Internet quality of service.     

A Measurement and Structural Model for Usability Evaluation of Shared Workspace Groupware

This study presents the development process of a set of questionnaire items to establish a measurement model for the usability of shared workspace groupware systems, which is suggested as a usability scale called SWUS, the Shared Workspace Usability Scale. Manifest variables and latent variables are based on the various dimensions of teamwork collated through the literature. A structural model was built on the measurement model. Models were evaluated through PLS-SEM methods. Data acquired on candidate questionnaire items from 398 international respondents who are users of five different online collaborative word processors was used for the model analysis. Of 37 candidate manifest variables, 22 were retained, which were measuring seven latent constructs: “3C Mechanisms,” “Grounding,” “Team Integration,” “Communication,” “Shared Access,” “Awareness,” and “Usability.” The data provided empirical evidence for the structural model based on these latent variables. The responses of the participants were not sensitive to differences between users in terms of gender and native language but showed sensitivity to age, experience with the evaluated software, and different shared workspace groupware evaluated in the study. Our structural model attempts to integrate several frameworks and models of usability for CSCW environments and provides empirical evidence for its reliability and validity based on subjective responses from users of shared workspace groupware.     

Effect of dextran polymers on the stability of soluble Escherichia coli penicillin G acylase

The stabilisation of Escherichia coli penicillin G acylase (PGA) by dextran polymers (of molecular weight 11.5, 37.7 and 71 kDa) was studied. The inactivation of both the native and dextran‐containing enzyme preparations obeyed first‐order kinetics at the temperature and pH values studied. The optimal concentrations of dextran polymers of molecular weight 11.5, 37.7 and 71 kDa stabilising PGA against inactivation were 50, 20 and 7.5 mmol dm⁻³ respectively. Dextran 11500 (11.5 kDa) gave 100‐fold protection of PGA against thermal inactivation of enzyme above 50 °C. The kinetic constants of the enzyme were slightly altered, but temperature and pH profiles were not altered by the dextrans. © 1999 Society of Chemical Industry     

Exploring adoption of augmented reality smart glasses: Applications in the medical industry

This study explores the use of augmented reality smart glasses (ARSGs) by physicians and their adoption of these products in the Turkish medical industry. Google Glass was used as a demonstrative example for the introduction of ARSGs. We proposed an exploratory model based on the technology acceptance model by Davis. Exogenous factors in the model were defined by performing semi-structured in-depth interviews, along with the use of an expert panel in addition to the technology adoption literature. The framework was tested by means of a field study, data was collected via an Internet survey, and path analysis was used. The results indicate that there were a number of factors to be considered in order to understand ARSG adoption by physicians. Usefulness was influenced by ease of use, compatibility, ease of reminding, and speech recognition, while ease of use was affected by ease of learning, ease of medical education, external influence, and privacy. Privacy was the only negative factor that reduced the perceived ease of use, and was found to indirectly create a negative attitude. Compatibility emerged as the most significant external factor for usefulness. Developers of ARSGs should pay attention to healthcare-specific requirements for improved utilization and more extensive adoption of ARSGs in healthcare settings. In particular, they should focus on how to increase the compatibility of ARSGs. Further research needs to be conducted to explain the adoption intention of physicians.     

Effects of suni-bug (<Emphasis Type="Italic">Eurygaster</Emphasis> spp.) damage on size distribution of durum wheat (<Emphasis Type="Italic">Triticum durum</Emphasis> L.) proteins

Wholemeal samples were obtained from five durum wheat cultivars at two different bug (Eurygaster spp.) damage levels (medium and high damage). The samples were incubated (60 and 120 min) and used in size exclusion high performance liquid chromatography (SE-HPLC) analyses. The results showed that the amount of larger polymeric protein (TP1) and smaller polymeric protein (TP2) obtained from total (sodium dodecyl sulfate soluble) proteins decreased significantly in the bug-damaged samples, while the amount of total larger monomeric proteins (TP3) increased. The polymeric/monomeric protein ratio of all cultivars decreased at 60 min of incubation with increasing damage level. For all cultivars, the ratio of unextractable polymeric protein (UPP%) significantly decreased at 60 min of incubation except cv. Diyarbakir. The results suggested that bug protease caused depolymerization and/or disaggregation of polymeric proteins to lower their average molecular size. The changes in protein structure as determined using SE-HPLC supported by the decreases in gluten content and gluten index values which decreased with suni-bug damage. Deteriorative effects of bug damage on durum wheat quality were found to be quite similar to those on bread wheats.