105,427 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
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
FIGURE 4 in Heracleum kurdistanicum (Apiaceae; Tordylieae), a new subalpine species from Dalanpar Mountain, NW Iran
No full textFIGURE 4. Distribution map of Heracleum kurdistanicum, H. argaeum, and H. schelkovnikovii.Published as part of Tabad, Mohammad Aref, Maroofi, Hosein & Rastegar, Azad, 2021, Heracleum kurdistanicum (Apiaceae; Tordylieae), a new subalpine species from Dalanpar Mountain, NW Iran, pp. 68-76 in Phytotaxa 508 (1) on page 74, DOI: 10.11646/phytotaxa.508.1.6, http://zenodo.org/record/542580
A novel triple-diameter pulsating heat pipe: Flow regimes and heat transfer performance
No full textA single-turn triple-diameter pulsating heat pipe (TD-PHP) with a total length of 250 mm (the evaporation, adiabatic, and condensation lengths were 25 mm, 125 mm, and 100 mm, respectively) made of a transparent Pyrex glass was designed and fabricated for the first time. The thermal performance and flow characteristics of the TD-PHP were compared with two other fabricated PHPs, the single-diameter (SD) and dual-diameter (DD) PHPs, to determine the effect of non-uniform channel diameters. The PHPs were mounted on a tilting frame, and their thermal performances were tested with various heat inputs, inclination angles, and filling ratios. The temperatures of the evaporation, condensation, and adiabatic sections and flow behaviors were monitored. Results indicated that circulating flow was enhanced by using TD-PHP, and thermal resistance was reduced considerably. The visualization results showed that the bubbles' generation, growth, and breakage leading to enlarged vapor plugs were enhanced because of the unbalanced gravitational forces owning to the channel with non-uniform diameter. Hence, the TD-PHP was functional even at inclination angles near the horizontal angle
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Effects of pre-germination treatments and sowing depths upon germination potential of some Acacia species
No full textSeeds of Acacia farnesiana (L.) Willd., A. salicina Lindley, A.
nilotica (L.) Willd. ex Del., A. ehrenbergiana Hayne, A. seyal Del., A.
saligna (Labill.) H. L. Wendl. and A. tortilis (Forssk.) Hayne were
subjected to pre-germination treatment. This was either by soaking
seeds in water for 24 or 48 or 72 hours or by placing them in boiling
water and left them to cool to the room temperature. All seeds were
sowed either at 2 or 4 or 6-cm at soil. The higher germination
percentage for all Acacia species was obtained after boiling seeds in
water and at 2-cm sowing depth apart from A. ehrenbergiana. It
showed no response to boiling in water but had the best result with
soaking in water for 24h. The results of this study suggest that boiling
seeds of the investigated Acacia species in water is recommended with
sowing depth not deeper than 4 cm.Corresponding Author:
Dr. Ibrahim Mohammed Aref
Department of Plant Production, College of Agriculture, King Saud University,
P. O. Box 2460 Riyadh 11451, Saudi Arabia
Email: [email protected]
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