With the capability of net shaping for complex 3D geometry, powder injection molding (PIM) is widely used for automotive parts, electronics and medical industry. In this study, an ultrasonic dental scaler tip produced by machining process was redesigned for the PIM process. An injection mold was designed and machined to produce the dental scaler tip by the PIM process.

Powder Injection Molding (PIM) has recently been recognized as an advanced manufacturing technology for low-cost mass production of metal or ceramic parts of complicated geometry. With this regards, design technology of dental scaler tip PIM mold, which has complex shape, with the help of computer-aided analysis for powder injection molding process was developed. Compter aided analysis results, such as filling pattern, weldline formation, and air vent position prediction were investigated and eventually showed good agreements with experimental results.

A solid stage sinterizacion model of the WC-Co is applied on this work. These results are compaired with the experimental data obtained for nanometric and micrometric sinter powder in an electric furnace and micrometric in a plasma reactor (using Abnormal Glow Discharge AGD). The correlations obtained allow the prediction of the sintering behavior in AGD for nanometric powder. The activation of the solid state sintering is shown with the decraease of the WC size and the use of AGD

Metal/diamond binary composite coatings on Al substrate without grit blasting were deposited by cold spray process with insitu powder preheating. Microstructural characterization of the as-sprayed coatings with different diamond size, strength and with/without Ti coating on diamond was carried out by OM and SEM. The assessment of basic properties such as tensile bond strength and hardness of the coatings, and the deposition efficiency was also carried out. Particular attention on the composite coatings was on the diamond fracture phenomenon during the cold spray deposition and the interface bonding between the diamond and the Fe-based metal matrix.

This study investigated a mechanism for controlling the shape of Cu nanocrystals fabricated using the polyol process, which considers the thermodynamic transition from a facetted surface to a rough surface and the growth mechanisms of nanocrystals with facetted or rough surfaces. The facetted surfaces were stable at relatively low temperatures due to the low entropy of perfectly facetted surfaces. Nanocrystals fabricated using a coordinative surfactant stabilized the facetted surface at a higher temperature than those fabricated using a non-coordinative surfactant. The growth rate of the surface under a given driving force was dependent on the surface structure, i.e., facetted or rough, and the growth of a facetted surface was a thermally activated process. Surface twins decreased the activation energy for growth of the facetted surface and resulted in rod- or wire-shaped nanocrystals

In the present study, we investigated the effects of genotypes on in vitro maturation and fertilization in porcine fresh/frozen-thawed oocytes. The porcine cumulus-oocyte complexes (COCs) were divided into four groups according to whether they were: (1) in vitro matured; (2) cryopreserved and in vitro matured; (3) in vitro fertilized and (4) cryopreserved, and in vitro fertilized. Maturation of porcine COCs was accomplished by incubation in NCSU23 medium. Immature oocytes were cryopreserved by Open Pulled Straws (OPS) method according to Vajta et al., (1998). Oocytes stained by Acetic-Orcein method were observed under the microscope. DNA extracted from the ovaries was analyzed by RAPD (random amplified polymorphic DNA) and SSCP (single strand conformational polymorphisrrt) method. The rates of oocytes maturation and fertilization were significantly high in AA genotype. The results indicated that in vitro maturation and fertilization in porcine fresh/frozen-thawed oocytes may be affected by genotypes in pigs.

Mecke!'s car t ilage is one of the ea rliest structu re to appear in a mandible derived from the lï rst branchi a l a rch and serves as the primorclium I"or the formation 01‘ mandible‘ mall eus. incus. and sphenomandibular li gament However. its direct role a nd the mechanism in mandibular clevelopment a re not well elucidated. 1'0 address t his Issue‘ we observed morphol ogical and histological changes and gene expression patterns in the Mecke!'s cart ilage 01" a cleveloping mouse. I"rom E13.5 to E18.5 embryos. using skeletal preparation samples a ncl routinely prepa red s lide secti ons for light mi croscopic observation in various sectional planes. The following methods were per |‘ ormecl : H&E staining I"or general hi st이 og i cal observation ‘ Von Kossafor detection of minerali zation. TRAP activ ity staining for locali zaLion 01’ osteoclastic cell s. immunohistochemistry for !Iα@-1 a ncl -9 forevaluati on of enzy matic activity 01" osteoclasLic cell s. a ncl in situ hybricli zation for detection of collagen type 1. Il. ancl X mRNA ex presslon‘ respecLively. AL E1 3.5 Mec kel's cartilage appeared as a V-shaped rod fused a t the micl line and thin minera li zed ma ndibular buccal plaLe was I"ormed lateral to. and at some clistance from. Meckel’s carti lage in an intramembranous ossi lïcation mocle. WiLh the progression of tooth development. t he Meckel’s in carti lage adjacent incisors revealecl hyperLrophi c chonclrocyte di ff"er entiation with minerali zation of the chondroid matrix. The Meckel’s car Li lage was replacecl with bone by o~ L eoc l asLs . showing strong immunoreact ivity for MMP- l ancl -9 from E16 5 Wi Lh ti me‘ Lhis bony replacement of Meckel's cartilage in an endochondral ossification mode was ex Lenclecl up Lo the mid-porLion of Lhe molar sockets til l EI8.5. The bony replacement of minera li zed hypertrophic chondrocyte zone expressing X collagen mHNA conLri buted to the formation of thick mandibular lingual plate . 1'hese f"i ndings suggesL LhaL mandibular formalion and development is closely relatecl with not only Mecke!'s carLi lage. buL also wiLh Lhc developing LooLh. and thaL C'erLai n in f"l uence from the developing tooth may play a role in detcrmin in g Lhe faLc of Meckel’s ca rLi lage cluring ma ndi bular development.