ABSTRACT
<p><b>OBJECTIVE</b>To analyze the stress distribution in temporomandibular joint (TMJ) with different depth of curve of Spee (CS) by three-dimensional finite element model (3D-FEM).</p><p><b>METHODS</b>FEM with different depth of CS were established. The depth was 2.50, 0 and 4.50 mm (model 0, 1, 2). The stress distribution were analyzed by software Abaqus. The change of stress were analyzed by paried t test.</p><p><b>RESULTS</b>The stress distribution patterns in TMJ with different depth of CS were similar. The Von Mises on the anterior surface of condyle and the Von Mises on the intermedial zone of the disc was higher. The S. Max. Principal of the condyle was mainly tensile stress. The S. Min. Principal of the condyle was mainly compressive stress. The S. Max. Principal of the disc was mainly tensile stress. The S.Min. Principal of the disc was mainly compressive stress.In model 0, the eviations of the Von Mises, the S.Max. Principal and the S.Min. Principal on the anterior surface of condyle were 0.1057 - 0.2298 MPa, -0.2243 - -0.3738 MPa and -0.3494 - -0.1165 MPa. The eviations of the Von Mises, the S.Max. Principal and the S. Min. Principal on the intermedial zone of the disc were 0.1099 - 0.6880 MPa, -0.3217 - 0 MPa and -1.2000 - -0.1000 MPa. The D-values of of Von Mises of condyle and disk between different models were extremely significant (P < 0.01).</p><p><b>CONCLUSIONS</b>With the same plane of occlusion, the stress distribution patterns of TMJ with different depth of CS is similar to that of normal occlusion. The final results also validate the anterior surface of condyle and intermediate zone of articular disc are the weight-bearing areas in TMJ. The changes of depth of CS change the value of the stress.</p>
Subject(s)
Humans , Cephalometry , Dental Occlusion , Dental Stress Analysis , Methods , Finite Element Analysis , Imaging, Three-Dimensional , Methods , Mandibular Condyle , Physiology , Stress, Mechanical , Temporomandibular Joint , Physiology , Temporomandibular Joint Disc , PhysiologyABSTRACT
In order to confirm the role that the 49th amino acid residue plays in enzymatic inactivity of Glutamine 49 phospholipase A2(Gln49-PLA2),site-directed mutagenesis of its 49th amino acid gene codon was conducted using PCR.Aspartic acid 49 phospholipase A2(Asp49-PLA2-Q49D-PLA2),the mutant of Gln49-PLA2 was expressed in E.coli with pET32a+ vector.The fusion protein,expressed as inclusion body,after being denatured,was on-column refolded and purified by immobilized metal affinity chromatography(IMAC),and then cleaved by Factor Xa.The mature Q49D-PLA2 mutant was obtained by Hitrap SP cation exchange and Superdex 75 gel filtration chromatography,with the recovery rate of 1.3%,and the specific activity of the mature Q49D-PLA2 mutant was 72 U/mg.It has been demonstrated that the 49th glutamine amino acid residue is the main reason in enzymatic inactivity of Gln49-PLA2 and the results are helpful for denatured protein refolding,especially in rich disulfide bonds conditions.
ABSTRACT
A separation technology of catalpol from Rehmannia with macroporpus adsorbent resins was investigated. The content of catalpol in the extract was determined by high performance liquid chromatography (HPLC). Nine different kinds of macroporous adsorbent resins were studied on the static capacity of adsorption and desorption, and D101 resin was best for the separation of the extraction solution of Rehmannia. The results showed that D101 resin had the highest static adsorption capacity of 69.2mg/g dry resin and its isotherm curve can be well described by Langmuir and Freudlich equation. The 5% ethanol elution on removal of the solvent under reduced pressure provided a brown powder, which was subjected to an open column chromatography on silica gel eluted with a CHCl3–MeOH gradient. The fraction eluted with CHCl3-MeOH (8∶2) was identified as catalpol and the purity of the compound was more than 90% purity by HPLC analysis. The yield of this separation technology was 6%.
ABSTRACT
<p><b>OBJECTIVE</b>To evaluate the effect of K2O addition on the crystallization property of dental glass-ceramics in the Li2O-SiO2-Al2O3-P2O5-ZnO system.</p><p><b>METHODS</b>Different content of K2O was added into Li2O-SiO2-Al2O3-P2O5-ZnO glass system. The heat-treated system of the glass-ceramics was determined by differential thermal analyses (DTA), then the crystallization components and the microstmcture of the glass-ceramics with different content of K2O were investigated from X-ray diffraction (XRD) analyses and scanning electron microscopy (SEM).</p><p><b>RESULTS</b>Addition of K2O helped to reduce the viscosity of the glass system and improved crystallization. More lithium disilicate crystals appeared after heated-treatment of the glass system which contained 5.3 wt% addition of K2O, and the homogeneously lath-shaped crystals were 4 gm in length.</p><p><b>CONCLUSION</b>Certain content of K2O can improve the crystallization property of dental glass-ceramics in the Li2O-SiO2-Al2O3-P2O5-ZnO system.</p>
Subject(s)
Ceramics , Crystallization , Dental Porcelain , Glass , Hot Temperature , Microscopy, Electron, Scanning , Silicon Dioxide , X-Ray DiffractionABSTRACT
A strain with relative higher phytase-producing ability, Aspergillus fumigatus WY-2 was screened from soil. The optimal pH and temperature for activity of the phytase from A.fumigatus WY-2 were 5.5 and 55 ℃, respectively. The gene encoding the phytase was amplified from genomic DNA of the strain by PCR, and a 1.5 kb DNA fragment was obtained and then was cloned into vector pMD18-T. The sequencing analysis revealed that the DNA fragment contained a whole open reading frame (ORF) of phytase gene. The phytase gene was 1459 bp in length included with a 61 bp intron and encoded 465 amino acids. A signal peptide encoding 26 amino acids was found at 5′end of the gene. There were 7 potential glycosylation sites in the phytase. The present phytase showed 91% identity in nucleotide sequence and 91% identity in deduced amino acids sequence to the previously reported A.fumigatus ATCC34625 phytase.