Damage of the Interface Between an Orthodontic Bracket and Enamel – the Effect of Some Elastic Properties of the Adhesive Material

The aim of this study was to investigate the magnitude of debonding stress of an orthodontic bracket bonded to the enamel with resin systems having different elastic properties. For the same purpose, sixty human premolars were randomly divided into four groups according to the adhesive system used for bonding brackets: G Fix flowable resin (GFI) with Everstick NET (ESN), GFI, G Aenial Universal Flow (GAU) with ESN, and GAU. The brackets were stressed in the occlusogingival direction on a universal testing machine. The values of debonding load and displacement were determined at the point of debonding. The elastic modulus of the tested materials was determined using nanoindentation. An analysis of variance showed a significant difference in the loads required to debond the bracket among the groups tested. The GAU group had the highest elastic modulus, followed by the GFI and ESN groups. ARI (Adhesive Remnant Index) scores demonstrated more remnants of the adhesive material on the bracket surface with adhesives having a higher elastic modulus. Taking into consideration results of the present in-vitro study, it can be concluded that the incorporation of a glass-fiber-reinforced composite resin (FRC) with a low elastic modulus between the orthodontic bracket and enamel increases the debonding force and strain more than with adhesive systems having a higher elastic modulus.</p

In Situ Hybridization and Monoclonal Antibody Analysis of Plasma Membrane Ca-Pump mRNA and Protein in Submandibular Glands of Rabbit, Rat and Man

The degree of supersaturation of saliva with calcium (Ca) is related to the mineral phase of enamel in erupted teeth, the incidence of caries, and the formation of calculus. The mechanisms for regulating salivary Ca concentration are therefore of relevance to dentistry. Sections of rabbit, rat and human submandibular gland (SMG) were processed for immuno-histochemistry with a specific anti-plasma membrane Ca-pump antibody, 5F10. Western blots confirm that the molecular weight of the proteins identified by our antibody (135 kDa) is consistent with an appropriate molecular weight for PMCA antigen (135-150 kDa). Tissue sections were also processed for in situ hybridization to study the distribution of the PMCA mRNA isoforms. In mammals, the PMCAl gene is reported to code for a PMCA protein with a role in maintaining the intracellular Ca levels in both epithelial and non-epithelial cells. Other genes including the PMCA2 and PMCA4 genes may code for PMCA proteins specific to Ca transporting tissues. Our studies demonstrate cytoplasmic labeling of PMCA mRNA with hPMCA-1 and hPMCA-4 specific cDNA probes in humans, and rPMCA-1 and rPMCA-2 specific oligonucleotide probes in rats. Labeling of PMCA protein and all mRNA isoforms was found in the cytoplasm of the interlobular and intralobular ducts (except for intercalated ducts). The demonstrated presence of PMCA in SMGs of rabbit, rat, and man, may suggest a role for PMCA in the regulation of intracellular Ca and in a mechanism for regulating and maintaining the high concentration of Ca in saliva

Economic Analysis of Stand-Alone Hybrid Wind/PV/Diesel Water Pumping System: A Case Study in Egypt

The design and evaluation of a stand-alone hybrid renewable energy system for pumping underground water for small farm irrigation is presented. Given environmental conditions, system specifications and daily load demand data, the optimal size of main system components is obtained using a sizing algorithm. Different renewable energy systems are compared using yearly simulations, on hourly base via specialized commercial software simulation packages PVSYST and HOMER, to simulate the system performance and to reach the optimum configurations based on the objective criteria. The criteria used in economic optimization are the net present cost and the cost of energy, with the percent of the capacity shortage. The following systems can be compared: PV only, PV with horizontal axis wind turbine, PV with vertical axis wind turbine, and PV with horizontal axis wind turbine and diesel generator and diesel generator only. The simulation also was carried out for different load patterns for optimum operation. The study was illustrated for climatic conditions of an isolated area in El-Tour City, Sinai, Egypt. The installed 3.42 kW PV water pumping system for irrigation purposes in the same site was also described

Collagen types I and II distribution: a relevant indicator for the functional properties of articular cartilage in immobilised and remobilised rabbit knee joints

The objective of the present work was to study changes in collagen type I and type II distribution in the articular cartilage of immobilised and remobilised rabbit knee joints. Twenty-four adult male rabbits were divided into three groups. One of the groups was a control group with free movement. The right knee joints of animals of the other two groups were immobilised for 4 weeks, followed by a period of 10 weeks of remobilisation for animals of group 3. Collagen type I and type II in the articular cartilage of tibial medial condyle of the right knee joint were estimated immunohistochemically in all groups. A degenerative process was evident after 4 weeks of immobilisation of rabbit knee joint leading to a partial shift in the density of collagen composition from type II to type I. After a period of 10 weeks of remobilisation, regenerative processes, evidenced by a restoration of collagen type II to normal, proceeded on top of degenerative processes, evidenced by the significantly higher content of collagen type I compared with normal. The present study pointed to the importance of assessment of collagen distribution as a relevant indicator for the functional properties of articular cartilage in immobilised and remobilised joints

Polymorphism in Seed Protein Electrophoretic Pattern and Species Relationships in the Genus Orobanche L

Abstract: Polymorphism in the banding profiles of the electrophoretic separation of seed proteins are used to reassess the taxonomic relationships between 21 samples representing eight species of the genus Orobanche L. (Orobanchaceae) that were collected from different cultivated and wild host in Egypt and Saudi Arabia. A high degree of similarity in the banding profile of samples of the same species is revealed in the studied taxa confirming the validity of seed proteins as a source of taxonomic criteria. Moreover, nine bands are common to all samples of the studied 21 species which may be indicative of their common origin and support the view that the genus Orobanche is a monophyletic group. The analysis of results using the NTSYS-pc program and the UPGMA and NJ clustering methods support the delimitation of species of Orobanche in two sections Orobanche W allr. and Trionychon wallr. Also, supports delimitation of the studied species in section Orobanche in three groups. Moreover the delimitation of the studied species belonging to section Trionychon in two groups supports the previous delimitation of this section