FTIR characterization of Ru/SiO2 catalyst for ammonia synthesis

Cataloged from PDF version of article.Carbon monoxide adsorption on a Ru/SiO2 catalyst was followed by IR spectroscopy to investigate the active sites. Using this catalyst, ammonia synthesis was achieved at 3508C in an N2/H2 gas mixture (N2/H2 < 3 : 1) for different reaction times. In addition to NH3 other NHx (x 1,2) species were also observed. CO adsorption after NH3 production was also performed to investigate the change in nature of the active sites. Based on the experimental evidence participation of Ru0 sites in ammonia synthesis was confirmed and a partial oxidation of the reduced Ru sites during the synthesis was observed. q 1999 Elsevier Science B.V. All rights reserved

Effect of molecular and electronic structure on the light harvesting properties of dye sensitizers

The systematic trends in structural and electronic properties of perylene diimide (PDI) derived dye molecules have been investigated by DFT calculations based on projector augmented wave (PAW) method including gradient corrected exchange-correlation effects. TDDFT calculations have been performed to study the visible absorbance activity of these complexes. The effect of different ligands and halogen atoms attached to PDI were studied to characterize the light harvesting properties. The atomic size and electronegativity of the halogen were observed to alter the relaxed molecular geometries which in turn influenced the electronic behavior of the dye molecules. Ground state molecular structure of isolated dye molecules studied in this work depends on both the halogen atom and the carboxylic acid groups. DFT calculations revealed that the carboxylic acid ligands did not play an important role in changing the HOMO-LUMO gap of the sensitizer. However, they serve as anchor between the PDI and substrate titania surface of the solar cell or photocatalyst. A commercially available dye-sensitizer, ruthenium bipyridine (RuBpy), was also studied for electronic and structural properties in order to make a comparison with PDI derivatives for light harvesting properties. Results of this work suggest that fluorinated, chlorinated, brominated, and iyodinated PDI compounds can be useful as sensitizers in solar cells and in artificial photosynthesis.Comment: Single pdf file, 14 pages with 7 figures and 4 table

A Simple Chaotic Neuron Model : Stochastic Behavior of Neural Networks

We have shortly reviewed the occurrence of the post-synaptic potentials between neurons, the relation between EEG and neuron dynamics, as well as methods of signal analysis. We supposed a simple stochastic model representing electrical activity of neuronal systems. The model is constructed using the Monte Carlo simulation technique. The results yielded EEG-like signals with their phase portraits in three-dimensional space. The Lyapunov exponent was positive, indicating a chaotic behavior. The correlation dimension of the EEG-like signals was found to be .92, which was smaller than those reported by others. It was concluded that this neuron model may provide valuable clues about the dynamic behavior of neural systems.Comment: 14 pages, 6 figure

Appendectomy in the surgical treatment of benign ovarian mucinous cystadenomas — is it necessary?

Objectives: To determine if appendectomy as an adjunctive procedure is necessary in the surgical treatment of benign ovarian mucinous cystadenomas. Material and methods: Retrospective analysis of clinical data: in a research hospital, obstetrics and gynecology depart­ment setting, 63 cases of benign ovarian mucinous cystadenomas confirmed in the pathological evaluation were revised. 59 had the complete clinical, final pathological and follow-up data available and were included. Results: 20.6% (13/59) went through an appendectomy. Basic characteristics of patients with different appendiceal pathologies did not show any significant differences. In the study group the mean age, parity, adnexial mass size were (40.1 ± 12.4); (1.3 ± 1.1) and (9.1 ± 5.3 cm), respectively. Patients were either operated laparoscopically (20), laparotomically (39) to perform a unilateral salpingoopherectomy/cystectomy. In 7 patients, oopherectomy was an additional procedure with: 2 abdominal hysterectomies, 4 cesarean sections and 1 total laparoscopic hysterectomy. 2 synchronous appendiceal pathologies (mucinous cystadenomas of the appendix) were defined in appendectomies performed. In these cases, the ovarian tumour sizes were: 7 cm and 4 cm. Conclusions: In the presence of a benign or borderline unilateral ovarian mucinous tumour as defined during the operation and especially if it is larger than 10–12 cm and with normal peritoneal and appendiceal gross morphology, appendectomy is not a necessary adjunctive procedure

Investigating the impact of customer orientation on innovativeness: evidence from born-global firms in Turkey

Our study develops and tests a research model that investigates the impact of born-globals’ customer orientation on innovativeness through the mediating roles of technological capability, relationship quality, and relationship information process. Data obtained from 197 small and medium-sized born-global firms in Turkey were used to gauge these relationships through structural equation modelling. The results suggest that born-globals’ customer orientation influences innovativeness indirectly through the mediating role of technological capability. Simply put, technological capability acts as a full mediator between customer orientation and innovativeness. Contrary to our predictions, relationship quality and relationship information process do not significantly influence innovativeness. Therefore, the empirical data do not support the mediating roles of relationship quality and relationship information process. In short, our study contributes to current knowledge by examining the factors that influence the innovativeness of born-globals using data obtained from born-globals in Turkey, which is a newly industrialised country

Externalizing, internalizing and fostering commitment: the case of born-global firms in emerging economies

This paper examines the HR practices of mature born-global firms from twenty-nine emerging economies. Through an examination of large scale survey data the paper questions the extent to which firm size impacts the employment of temporary workers, the employment of skilled workers and the extent of employee training. Findings suggest that as firm size increases the use of temporary workers decreases, the number of skilled workers increases and the number of employees receiving training also increases. The paper highlights how born-global firms are able to shift away from externalized, market-based approaches towards more internalized, commitment-based approaches in order to survive, adapt and grow

In Vitro Neuroprotective Effect Evaluation of Donepezil‐Loaded PLGA Nanoparticles‐Embedded PVA/PEG Nanofibers on SH‐SY5Y Cells and AP‐APP Plasmid Related Alzheimer Cell Line Model

Recently developed nanoparticles and nanofibers present new brain‐specific treatment strategies, especially for Alzheimer's disease treatment. In this study, donepezil (DO)‐loaded PLGA nanoparticles (DNP) are embedded in PVA/PEG nanofibers (DNPF) produced by pressurized gyration for sublingual administration. SEM images showed produced drug‐loaded and pure nanofibers, which have sizes between 978 and 1123 nm, demonstrated beadless morphology and homogeneous distribution. FT‐IR, XRD, and DSC results proved the produced nanoparticles and fibers to consist of the DO and other polymers. The in vitro drug release test presented that the release profile of DO is completed at the end of the 18th day. It is released by the first order kinetic model. DNPF has an ultra‐fast release profile via its disintegration within 2 sec, which proved itself to be suitable for the administration sublingually. All samples presented above ≈90% cell viability via their non‐toxic natures on SH‐SY5Y human neuroblastoma cells by using Alamar blue assay. The anti‐Alzheimer effects of DO, DNP, and DNPF are evaluated on the Aβ1−42‐induced SH‐SY5Y cells at 1, 5, and 10 µM as treatment groups. The 1 µM dosage exhibited the most significant neuroprotective effects, which showed enhanced cellular uptake and superior modulation of Alzheimer's‐related proteins, including tau and Aβ

Assessing the validity and reliability of family factors on physical activity: A case study in Turkey

Background: Childhood obesity rates have been rising rapidly in developing countries. A better understanding of the risk factors and social context is necessary to inform public health interventions and policies. This paper describes the validation of several measurement scales for use in Turkey, which relate to child and parent perceptions of physical activity (PA) and enablers and barriers of physical activity in the home environment. Method: The aim of this study was to assess the validity and reliability of several measurement scales in Turkey using a population sample across three socio-economic strata in the Turkish capital, Ankara. Surveys were conducted in Grade 4 children (mean age = 9.7 years for boys; 9.9 years for girls), and their parents, across 6 randomly selected schools, stratified by SES (n = 641 students, 483 parents). Construct validity of the scales was evaluated through exploratory and confirmatory factor analysis. Internal consistency of scales and test-retest reliability were assessed by Cronbach\u27s alpha and intra-class correlation. Results: The scales as a whole were found to have acceptable-to-good model fit statistics (PA Barriers: RMSEA = 0.076, SRMR = 0.0577, AGFI = 0.901; PA Outcome Expectancies: RMSEA = 0.054, SRMR = 0.0545, AGFI = 0.916, and PA Home Environment: RMSEA = 0.038, SRMR = 0.0233, AGFI = 0.976). The PA Barriers subscales showed good internal consistency and poor to fair test-retest reliability (personal α = 0.79, ICC = 0.29, environmental α = 0.73, ICC = 0.59). The PA Outcome Expectancies subscales showed good internal consistency and test-retest reliability (negative α = 0.77, ICC = 0.56; positive α = 0.74, ICC = 0.49). Only the PA Home Environment subscale on support for PA was validated in the final confirmatory model; it showed moderate internal consistency and test-retest reliability (α = 0.61, ICC = 0.48). Discussion: This study is the first to validate measures of perceptions of physical activity and the physical activity home environment in Turkey. Our results support the originally hypothesized two-factor structures for Physical Activity Barriers and Physical Activity Outcome Expectancies. However, we found the one-factor rather than two-factor structure for Physical Activity Home Environment had the best model fit. This study provides general support for the use of these scales in Turkey in terms of validity, but test-retest reliability warrants further research