925 research outputs found
The Formation of the Intermetallic-Containing Pd2Sn Alloy: The Creation of the Isolated Adsorption Sites
In the current study, tin-promoted Pd / MWNTs synthesized via polyol process were developed. TEM images evidences resulted in the formation of highly-dispersed Pd-Sn nanoparticles. The formation of Pd2Sn structural phase was confirmed by XRD and TPR techniques, composed mainly of intermetallic spe-cies, supported by XPS results. In this research, we applied intermetallic-containing tin-promoted catalysts for the selective hydrogenation reaction of acetylene as the case study. The presence of a discontinuity in the Arrhenius plots could come from the kinetic factor as a result of change in acetylene coverage on Pd metallic ensembles. The intermetallic-containing assembled catalysts led to the good management of cata-lytic performance due to the creation of isolated adsorption sites on the catalyst surface, resulting in the higher ethylene selectivity.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3521
The Role of Pore Structure of SMFs-based Pd Nanocatalysts in Deactivation Behavioral Pattern Upon Acetylene Hydrogenation Reaction
In this research, SMFs panels were applied for further deposition of CNFs, ZnO and Al2O3 to hydro-genate selectively acetylene to ethylene. To understand the role of different structures of the examined supports, the characterization methods of SEM, ASAP, NH3-TPD and N2 adsorption-desorption isotherms were used. Following the characterization of green oil by FTIR, the presence of more unsaturated constitu-ents and then, more branched hydrocarbons formed upon the reaction over alumina-supported catalyst in comparison with the ones supported on CNFs and ZnO was confirmed, which in turn, could block the pores mouths. Besides the limited hydrogen transfer, the lowest pore diameters of Al2O3 / SMFs close to the sur-face, supported by N2 adsorption-desorption isotherms could explain the fast deactivation of this catalyst, compared to the other ones.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3521
Psychological disorders inwomen with spontaneous preterm delivery
Background: Preterm delivery is a major cause of mortality in infants. The prevalence of preterm delivery is rising over time. Psychological disorders have been associated with preterm delivery. In this study, we aimed to compare the frequency of psychological disorders among women with spontaneous preterm versus term delivery. Methods: In this cross-sectional study, psychological disorders in 60 women, who experienced spontaneous term delivery and in 60 women who had spontaneous preterm delivery (gestational age of less than 37 weeks) were examined, using symptom checklist-90-revised questionnaire (SCL-90-R) in Akbarabadi teaching hospital during 2014. The question scales were compared between the two groups, using Chi 2 test and independent t-test. Results: The mean age of the participants was 23.58±4.26, and 23.90±4.71 in preterm-delivery and term-delivery groups, respectively (P value = 0.22). The mean score of Symptom checklist-90-revised questionnaire (SCL-90-R) was 102.21 (±35.81) in women with preterm delivery, and it was 59.14±22.17 in women with term delivery, which was significantly different (P value < 0.001). In addition, the total score and the score for all the subscales of psychological disorder were higher in women with preterm delivery (P value < 0.001). Conclusions: Psychological disorders in pregnancy are associated with an increased risk of preterm delivery. Therefore, future studies should focus on finding ways to lower psychological disorders in late pregnancy. © 2016, Shiraz University of Medical Sciences
The Complexity of Routing with Few Collisions
We study the computational complexity of routing multiple objects through a
network in such a way that only few collisions occur: Given a graph with
two distinct terminal vertices and two positive integers and , the
question is whether one can connect the terminals by at least routes (e.g.
paths) such that at most edges are time-wise shared among them. We study
three types of routes: traverse each vertex at most once (paths), each edge at
most once (trails), or no such restrictions (walks). We prove that for paths
and trails the problem is NP-complete on undirected and directed graphs even if
is constant or the maximum vertex degree in the input graph is constant.
For walks, however, it is solvable in polynomial time on undirected graphs for
arbitrary and on directed graphs if is constant. We additionally study
for all route types a variant of the problem where the maximum length of a
route is restricted by some given upper bound. We prove that this
length-restricted variant has the same complexity classification with respect
to paths and trails, but for walks it becomes NP-complete on undirected graphs
Braneworld non-minimal inflation with induced gravity
We study cosmological inflation on a warped DGP braneworld where inflaton
field is non-minimally coupled to induced gravity on the brane. We present a
detailed calculation of the perturbations and inflation parameters both in
Jordan and Einstein frame. We analyze the parameters space of the model fully
to justify about the viability of the model in confrontation with recent
observational data. We compare the results obtained in these two frames also in
order to judge which frame gives more acceptable results in comparison with
observational data.Comment: 40 pages, 23 figures, Revised version, Accepted for publication in
Phys. Rev.
Droplet-like bent multimode fiber sensor for temperature and refractive index measurement
This work proposes and demonstrates a bent multimode interference (MMI) sensor for refractive index and temperature measurement. The MMI structure was fabricated by successive splicing between single-mode-multimodesingle- mode (SMS) fibers. A droplet-like bent was introduced in the multimode fiber section for excitation of modes into the acrylate coating. The excitation of higher modes into the acrylate coating is particularly interesting due high thermooptic coefficient of acrylate which could improve temperature sensitivity, while evanescent field interaction of modes at the acrylate surface with surrounding material could be used for refractive index sensing. These modes experienced phase changes due to temperature and/or refractive index changes, consequently shift the spectra of the sensor. The sensor structure was simulated using BeamProp software to determine the required bending to excite light into acrylate coating for sensing. In experiment, a 3.5 mm bent sensor demonstrated refractive index sensitivity of 42.41 nm/RIU tested with refractive index between 1.30-1.395. Meanwhile, temperature sensitivity of 1.317nm/°C was attained using 5 mm bent sensor between 25 °C to 35 °C. The low cost and simple sensor structure is desirable in many applications including for detection, diagnosis, and determine of health, safety, environmental, liquid food, and water quality control
Virtual Summer School: Alternative Methods and Models in Science: A Multidisciplinary In Vitro Approach
Multi-image-feature-based hierarchical concrete crack identification framework using optimized svm multi-classifiers and d–s fusion algorithm for bridge structures
Cracks in concrete can cause the degradation of stiffness, bearing capacity and durability of civil infrastructure. Hence, crack diagnosis is of great importance in concrete research. On the basis of multiple image features, this work presents a novel approach for crack identification of concrete structures. Firstly, the non-local means method is adopted to process the original image, which can effectively diminish the noise influence. Then, to extract the effective features sensitive to the crack, different filters are employed for crack edge detection, which are subsequently tackled by integral projection and principal component analysis (PCA) for optimal feature selection. Moreover, support vector machine (SVM) is used to design the classifiers for initial diagnosis of concrete surface based on extracted features. To raise the classification accuracy, enhanced salp swarm algorithm (ESSA) is applied to the SVM for meta-parameter optimization. The Dempster–Shafer (D–S) fusion algorithm is utilized to fuse the diagnostic results corresponding to different filters for decision making. Finally, to demonstrate the effectiveness of the proposed framework, a total of 1200 images are collected from a real concrete bridge including intact (without crack), longitudinal crack, transverse crack and oblique crack cases. The results validate the performance of proposed method with promising results of diagnosis accuracy as high as 96.25%
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