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

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

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

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

The construct validity and reliability of the Turkish version of Spreitzer's psychological empowerment scale

<p>Abstract</p> <p>Background</p> <p>Today, many organizations have adopted some kind of empowerment initiative for at least part of their workforce. Over the last two decades, two complementary perspectives on empowerment at work have emerged: structural and psychological empowerment. Psychological empowerment is a motivational construct manifested in four cognitions: meaning, competence, self-determination and impact. The aim of this article is to examine the construct validity and reliability of the Turkish translation of Spreitzer's psychological empowerment scale in a culturally diverse environment.</p> <p>Methods</p> <p>The scale contains four dimensions over 12 statements. Data were gathered from 260 nurses and 161 physicians. The dimensionality of the scale was evaluated by exploratory factor analyses. To investigate the multidimensional nature of the empowerment construct and the validity of the scale, first- and second-order confirmatory factor analysis was conducted. Furthermore, Cronbach alpha coefficients were assessed to investigate reliability.</p> <p>Results</p> <p>Exploratory factor analyses revealed that four factors in both solutions. The first- and second-order factor analysis indicated an acceptable fit between the data and the theoretical model for nurses and physicians. Cronbach alpha coefficients varied between 0.81-0.94 for both groups, which may be considered satisfactory.</p> <p>Conclusions</p> <p>The analyses indicated that the psychometric properties of the Turkish version of the scale can be considered satisfactory.</p

Correlation of gene expression with magnetic resonance imaging features of retinoblastoma: a multi-center radiogenomics validation study

OBJECTIVES To validate associations between MRI features and gene expression profiles in retinoblastoma, thereby evaluating the repeatability of radiogenomics in retinoblastoma. METHODS In this retrospective multicenter cohort study, retinoblastoma patients with gene expression data and MRI were included. MRI features (scored blinded for clinical data) and matched genome-wide gene expression data were used to perform radiogenomic analysis. Expression data from each center were first separately processed and analyzed. The end product normalized expression values from different sites were subsequently merged by their Z-score to permit cross-sites validation analysis. The MRI features were non-parametrically correlated with expression of photoreceptorness (radiogenomic analysis), a gene expression signature informing on disease progression. Outcomes were compared to outcomes in a previous described cohort. RESULTS Thirty-six retinoblastoma patients were included, 15 were female (42%), and mean age was 24 (SD 18) months. Similar to the prior evaluation, this validation study showed that low photoreceptorness gene expression was associated with advanced stage imaging features. Validated imaging features associated with low photoreceptorness were multifocality, a tumor encompassing the entire retina or entire globe, and a diffuse growth pattern (all p < 0.05). There were a number of radiogenomic associations that were also not validated. CONCLUSIONS A part of the radiogenomic associations could not be validated, underlining the importance of validation studies. Nevertheless, cross-center validation of imaging features associated with photoreceptorness gene expression highlighted the capability radiogenomics to non-invasively inform on molecular subtypes in retinoblastoma. CLINICAL RELEVANCE STATEMENT Radiogenomics may serve as a surrogate for molecular subtyping based on histopathology material in an era of eye-sparing retinoblastoma treatment strategies. KEY POINTS - Since retinoblastoma is increasingly treated using eye-sparing methods, MRI features informing on molecular subtypes that do not rely on histopathology material are important. - A part of the associations between retinoblastoma MRI features and gene expression profiles (radiogenomics) were validated. - Radiogenomics could be a non-invasive technique providing information on the molecular make-up of retinoblastoma