44 research outputs found

    Comparison of Hydrothermal Method and Ultrasonic Method in Zeolite Synthesis and Investigation of Catalytic Activities of Synthesized Zeolites

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    In this study, ZSM-5 and beta zeolites, which constitutes the most industrially important artificial zeolite species., were synthesized and the effects of synthesized zeolite in catalytic cracking were investigated. ZSM-5 and beta zeolite were synthesized by varying synthesis time, synthesis method and calcination temperatures. The composition of the synthesis was kept constant and than compared with ultrasonic method and hydrothermal method. ZSM-5 and beta zeolite derivatives were synthesized with changing the synthesis method. Beta zeolite is obtained as a result of the synthesis with low temperature in 20 minutes with using of ultrasonic method. On the other hand, ZSM-5 zeolite is achieved at the end of the synthesis with high temperature in 72 hours with using of hidrotermal method. The X-Ray Powder Diffraction (XRD) patterns and Scanning Electron Microscopy (SEM) images of ZSM-5 zeolites showed that the crystal structure and phase purity of ZSM-5 increased with increase in synthesis time and not affected by the calcination temperature. Otherwise, the crystal structure and phase purity of beta zeolite increased with increase in calcination temperature. To determine the catalytic performances of the products, the catalytic cracking processes were performed. First of all, thermal cracking was realized without catalyst for comparison with the others. Then, catalytic cracking was carried out with CaO, Al2O3, SiO2, natural zeolite, ZSM-5 and beta zeolite. Compairing the results, the catalytic efficiency of the synthesized products were higher than the others. Yield of over 70 % was obtained with synthesized ZSM-5 and zeolite beta

    A Linear Well-Posed Solution To Recover High-Frequency Information For Super Resolution Image Reconstruction

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    Multiview super resolution image reconstruction (SRIR) is often cast as a resampling problem by merging non-redundant data from multiple images on a finer grid, while inverting the effect of the camera point spread function (PSF). One main problem with multiview methods is that resampling from nonuniform samples (provided by multiple images) and the inversion of the PSF are highly nonlinear and ill-posed problems. Non-linearity and ill-posedness are typically overcome by linearization and regularization, often through an iterative optimization process, which essentially trade off the very same information (i.e. high frequency) that we want to recover. We propose a different point of view for multiview SRIR that is very much like single-image methods which extrapolate the spectrum of one image selected as reference from among all views. However, for this, the proposed method relies on information provided by all other views, rather than prior constraints as in single-image methods which may not be an accurate source of information. This is made possible by deriving explicit closed-form expressions that define how the local high frequency information that we aim to recover for the reference high resolution image is related to the local low frequency information in the sequence of views. The locality of these expressions due to modeling using wavelets reduces the problem to an exact and linear set of equations that are well-posed and solved algebraically without requiring regularization or interpolation. Results and comparisons with recently published state-of-the-art methods show the superiority of the proposed solution

    Motion Compensation Using Critically Sampled Dwt Subbands For Low-Bitrate Video Coding

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    In this paper, we propose a novel motion estimation/motion compensation (ME/MC) method for wavelet-based (i.e. in-band) motion compensated temporal filtering (MCTF), with application to low-bitrate video coding. Unlike the conventional in-band MCTF algorithms, which require redundancy to overcome the shift-variance problem of critically sampled (i.e. complete) discrete wavelet transforms (DWT), we perform ME/MC steps directly on DWT coefficients by avoiding the need of shift-invariance. We omit upsampling, inverse-DWT (IDWT), and calculation of redundant DWT coefficients, while achieving arbitrary subpixel accuracy without interpolation, and high video quality even at very low-bitrates, by deriving the exact relationships between DWT subbands of input image sequences. Experimental results demonstrate the accuracy of the proposed method, confirming that our model for ME/MC effectively improves video coding quality

    In-Band Sub-Pixel Registration Of Wavelet-Encoded Images From Sparse Coefficients

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    Sub-pixel registration is a crucial step for applications such as super-resolution in remote sensing, motion compensation in magnetic resonance imaging, and nondestructive testing in manufacturing, to name a few. Recently, these technologies have been trending towards wavelet-encoded imaging and sparse/compressive sensing. The former plays a crucial role in reducing imaging artifacts, while the latter significantly increases the acquisition speed. In view of these new emerging needs for applications of wavelet-encoded imaging, we propose a sub-pixel registration method that can achieve direct wavelet domain registration from a sparse set of coefficients. We make the following contributions: (i) We devise a method of decoupling scale, rotation, and translation parameters in the Haar wavelet domain, (ii) we derive explicit mathematical expressions that define in-band sub-pixel registration in terms of wavelet coefficients, (iii) using the derived expressions, we propose an approach to achieve in-band sub-pixel registration, avoiding back and forth transformations. (iv) Our solution remains highly accurate even when a sparse set of coefficients are used, which is due to localization of signals in a sparse set of wavelet coefficients. We demonstrate the accuracy of our method, and show that it outperforms the state of the art on simulated and real data, even when the data are sparse

    Maternal plasma levels of cytokines in normal and preeclamptic pregnancies and their relationship with diastolic blood pressure and fibronectin levels

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    Background. To determine the plasma concentrations of placental growth factor (PLGF), vascular endothelial growth factor (VEGF), transforming growth factor-beta(1) (TGF-beta(1) ), soluble tumor necrosis factor alpha receptor (sTNFp55), interleukin-2 receptor (IL-2R), and interleukins 6 and 10 (IL-6, IL-10) in normotensive and preeclamptic women, and to evaluate the correlations between these cytokines and the diastolic blood pressure and fibronectin levels

    Effect of Chronic Periodontitis on Serum and Gingival Crevicular Fluid Oxidant and Antioxidant Status in Patients With Familial Mediterranean Fever Before and After Periodontal Treatment

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    Background: The aim of this study is to investigate the impact of periodontal status on oxidant/antioxidant status in patients with chronic periodontitis (CP) who experienced familial Mediterranean fever (FMF) and their response to non-surgical periodontal therapy.Background: The aim of this study is to investigate the impact of periodontal status on oxidant/antioxidant status in patients with chronic periodontitis (CP) who experienced familial Mediterranean fever (FMF) and their response to non-surgical periodontal therapy.Methods: Data were obtained from 13 patients with FMF with generalized CP (FMF-CP), 15 systemically healthy patients with generalized CP, 15 systemically and periodontal healthy controls (HCs), and 14 periodontally healthy patients with FMF (FMF-HC). Each participant&rsquo;s total oxidant status (TOS), total antioxidant status (TAS), and oxidative stress index (OSI) in their gingival crevicular fluid (GCF) and serum were recorded. Probing depth, clinical attachment level, and gingival and plaque indices in each participant were also measured. The GCF and clinical parameters at baseline and 6 weeks after periodontal treatment were recorded.Results: The study showed statistically significant improvement of clinical parameters in both FMF-CP and CP groups after periodontal treatment. The baseline GCF-TOS and OSI levels were significantly higher in the CP group compared with the FMF-CP group (P &lt;0.05). After periodontal treatment, the GCF-TOS levels were significantly reduced in members of the FMF-CP group (P &lt;0.05). The GCF-TAS levels in members of the FMF-CP group were significantly higher than those of members of the HC group at baseline (P &lt;0.05). Serum-TAS levels in the FMF-CP group were significantly higher than those in the CP and HC groups at baseline (P &lt;0.05). The GCF-TOS level in the FMF-CP group was significantly higher than that in the FMF-HC group at baseline and 6 weeks. However, there were no significant differences in the serum-TOS and serum-OSI levels of those in the FMF-CP and CP groups at baseline and 6 weeks (P &gt;0.05).Conclusion: The results of the present study show that patients with FMF-CP displayed reduced oxidative stress and increased antioxidant status compared with those in the CP and HC groups.</p
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