508 research outputs found
Effect of modifications of dual acid‐etched implant surfaces on periimplant bone formation. Part II: calcium phosphate coatings
No full textThe aim of the present study was to test the hypothesis that calcium phosphate coatings of dual acid-etched surfaces (DAEs) can improve periimplant bone regeneration. Ten adult female foxhounds received experimental titanium screw implants in the mandible 3 months after removal of all premolar teeth. Five types of surface states were evaluated in each animal: (i) implants with a machined surface (MS) (Control 1); (ii) implants with a DAE (Control 2); (iii) implants with a DAE coated with collagen I (Control 3); (iv) implants with a DAE with mineralized collagen I; and (v) implants with a DAE with a hydroxylapatite (HA) coating. Periimplant bone regeneration was assessed by histomorphometry after 1 and 3 months in five dogs each by measuring bone implant contact (BIC) and the volume density of the newly formed periimplant bone (BVD). After 1 month, mean BIC of experimental implants did not differ significantly from implants with DAE and collagen-coated surfaces, but was significantly higher than the MS implants. BVD was enhanced significantly only in implants with mineralized collagen coating compared with DAE and collagen-coated controls. After 3 months, the mean values of BIC had increased significantly in the group of implants with HA and mineralized collagen coating but were not significantly different from implants with DAE and collagen-coated surfaces. The same held true for the mean BVD values. In conclusion, the present study could not verify the hypothesis that calcium phosphate coatings of DAEs in the present form enhanced periimplant bone formation compared with the DAE surface alone. To cite this article:Schliephake H, Aref A, Scharnweber D, Ro ss ler S, Sewing A. Effect of modifications of dual acid-etched implant surfaces on periimplant bone formation: part II. Calcium phosphate coatings.Clin. Oral Impl. Res. 20, 2009; 38-44.German Federal Ministry of Education and Research BMBF [03N4021
Plasmonic internal-photoemission-based Si photodetector design suitable for optical communication
No full textWe propose a high-performance plasmonic photodetector based on the internal photoemission (IPE) process for the C-band communication wavelength. This photodetector takes advantage of an embedded nanohole array in Schottky metal. Owing to localized surface plasmon resonance, the absorption of the active metal layer increases, which results in the generation of more hot carriers and subsequently compensates for the low efficiency of IPE-based photodetectors. Simulations show that for the proposed photodetector with 2-nm-thick Au, Cu, and Ag Schottky contacts, the absorptance dramatically enhances to 95.1%, 93.2%, and 98.2%, respectively, at the wavelength of 1.55 µm. For the detector based on Au, the highest external quantum efficiency of 25.3% and responsivity of 0.32 A/W are achieved at a reverse bias voltage of 1 V. Furthermore, the 3 dB bandwidth can exceed 369 GHz owing to the low capacitance of the structure and the fast transit time of carriers from the thin p-Si layer. Finally, by studying the current–voltage characteristics of the photodetector, it is shown that under the reverse bias voltage of 1 V, the dark current is 665 nA at room temperature, and by reducing the temperature to 200 K, it improves three orders of magnitude and decreases to 810 pA.</jats:p
Effect of modifications of dual acid‐etched implant surfaces on peri‐implant bone formation. Part I: organic coatings
No full textThe aim of the present study was to test the hypothesis that peri-implant bone formation can be improved by modifying dual acid-etched (DAE) implant surfaces using organic coatings that enhance cell adhesion and osteogenic differentiation. Ten adult female foxhounds received experimental titanium implants in the mandible 3 months after removal of all premolar teeth. Six types of implants were evaluated in each animal: (i) implants with a machined surface (MS), (ii) implants with a DAE surface topography, (iii) implants with an acid-etched surface coated with RGD peptides, (iv) implants with an acid-etched surface coated with collagen I, (v) implants with an acid-etched surface coated with collagen I and chondroitin sulphate (CS), (vi) implants with an acid-etched surface coated with collagen I and CS and recombinant human bone morphogenetic protein-2. Peri-implant bone regeneration was assessed by histomorphometry after 1 and 3 months in five dogs each by measuring bone implant contact (BIC) and the bone volume density (BVD) of the newly formed peri-implant bone. After 1 month, mean BIC was significantly higher in the coated implants group than in the MS group. There was no significant difference when mean BIC in the DAE group was compared with implants with any of the organic coatings, but the difference was significant when compared with the MS implants. Differences in mean BVD value did not reach significance between any of the surfaces. After 3 months, the same held true for the mean BIC of all the groups except for Coll I. Mean volume density of the newly formed bone was higher in all the surface modifications, albeit without statistical significance. It is concluded that with the exception of Coll I, the tested organic surface coatings on DAE surfaces did not improve peri-implant bone formation when compared with the DAE surfaces but enhanced BIC when compared with the MSs. To cite this article:Schliephake H, Aref A, Scharnweber D, Bierbaum S, Sewing A. Effect of modifications of dual acid-etched implant surfaces on peri-implant bone formation. Part I: Organic coatings.Clin. Oral Impl. Res. 20, 2009; 31-37.BMBF [03N4021
Exact nonlinear frequency division multiplexing in lossy fibers
No full textThe path-average approximation penalizes NFDM transmission over lumped amplified fiber links.We investigate suitably tapered lossy fibers to overcome the approximation error induced by the path average, making the NFDM transmission exact. Error vector magnitude gains up to 4.8 dB are observed.Accepted Author ManuscriptTeam Sander Wahl
Aref el Aref & Bedouin sheikhs
No full textTitle and date from: photographer's logbook: Matson Registers, v. 1, [1934-1939].Gift; Episcopal Home; 1978
Effects of Initial Thinning on the Growth and Biomass Characteristics of Zizyphus spina-christi Trees
No full textSeedlings of Zizyphus spina-christi trees grown from seeds were planted intensively in the field at the Experiments and Research Station of College of Agriculture, King Saud University near Riyadh City. After
a year, the trees were subjected to thinning through three consecutive years and evaluated for growth and biomass production. Starting from the second year of thinning, the thinned trees increased stem diameter and
all above-ground biomass components. Branches and foliage biomass ratio also increased due to thinning at the expense of stem biomass ratio. Unthinned trees were superior in biomass production after three years of the treatment application.Corresponding Author:
Prof. Ibrahim Mohammed Aref
Forest Sciences and Environment, College of Food Science and Agiculture, King Saud University
PO. Box 2460, Riyadh, 11451, Saudi Arabia
Email: [email protected]
Dataset of synthetic modular graphs from LFR and ABCD benchmark models for community detection
No full textThis dataset contains randomly generated networks (random graphs) from a study on community detection. In total there are 50 network files. This includes 30 ABCD graphs and 20LFR graphs as described in the article linked below. Each network is provided in .gml format.This dataset is provided under a CC BY-NC-SA Creative Commons v 4.0 license (Attribution-NonCommercial-ShareAlike). This means that other individuals may remix, tweak, and build upon these data non-commercially, as long as they provide citations to this data repository (https://doi.org/10.6084/m9.figshare.24257293), the reference article listed below, and license the new creations under the identical terms.For more information about the data, one may refer to the articles below:Samin Aref and Mahdi Mostajabdaveh "Analyzing Modularity Maximization in Approximation, Heuristic, and Graph Neural Network Algorithms for Community Detection" ArXiv 2023.</p
Oral microbiota and oral aspects in celiac disease before and after gluten free diet
No full textBackground: Celiac disease is an autoimmune disease. The immune reaction produces an inflammation that damages the lining of the small intestine, in particular the duodenal mucosa, leading to a general malabsorption of nutrients that causes intestinal symptoms and manifestations to the oral cavity. The aim of the work is to identify any dental or mucosal manifestations of celiac disease before and after the gluten-Free diet, in order to find a new diagnostic method for this disease. The oral examination could make a significant contribution to the revelation of celiac disease. Finding the connection between this disease and oral problems, the oral clinical examination could be considered an easy, non-invasive and effective method for the identification of autoimmune disease.
Methods: 300 celiac patients will be examined before the gluten-free diet (T0) and then they will be reevaluated three months after the beginning of diet (T1). In T0 will be performed: anamnesis; DMFT / dmft (decayed, missing, filled teeth); evaluation of mucosal lesions such as recurrent aphthous stomatitis; collection of information related to the last professional oral hygiene and the brushing habits; pH through a saliva sample examined with pH meter; - quantitative analysis of basal salivary flow; identification of C-reactive protein that detects and controls an inflammation in the organism; FMPS (full mouth plaque score) and FMBS (full mouth bleeding score) considering six surface a tooth in order to exclude poor oral hygiene as a cause of inflammation; microbiological analysis (GENOMIC KIT for the extraction of bacterial DNA processed in PCR-Real-Time). The patients will be treated with professional oral hygiene to remove tartar and plaque. In the second visit (T1) the parameters considered in T0 will be re-evaluated using the initial methods. The data obtained will be compared with those observed in T0.
Results: Comparing 300 patients' clinical exams, it will be possible to define if celiac patients have more oral manifestations than healthy people.
Conclusions: The identification of oral signs caused by celiac disease will give more importance to clinical oral examination because this exam will be considered an easy, non-invasive and effective method to identify' the autoimmune disease
Outils et évaluation Actes du congrès de l’Actualité de la recherce en éducation et en formation (AREF
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