Mechanical strength and corrosion resistance of Al-additive friction stir welded AZ31B joints

Compared to other structural alloys,magnesium alloys have a relatively poor corrosion resistance and low mechanical strength,which can be further deteriorated when these alloys are subjected to joining processes using the existing joining methods.Herein,we propose for the first time an additive friction stir-welding(AFSW)using fine Al powder as an additive to improve the mechanical strength as well as corrosion resistance of AZ31B weld joints.AFSW is a solid-state welding method of forming a high-Al AZ31B joint via an in-situ reaction between pure Al powders filled in a machined groove and the AZ31B matrix.To optimize the process parameters,AFSW was performed under different rotational and transverse speeds,and number of passes,using tools with a square or screw pin.In particular,to fabricate a weld zone,where the Al was homogenously dispersed,the effects of the groove shape were investigated using three types of grooves:surface one-line groove,surface-symmetric grooves,and inserted symmetric grooves.The homogenous and defect-less AFS-welded AZ31B joint was successfully fabricated with the following optimal parameters:1400 rpm,25 mm/min,four passes,inserted symmetric grooves,and the tool with a square pin.The AFSW fully dissolved the additive Al intoα-Mg and in-situ precipitated Mg_(17)Al_(12)particles,which was confirmed via scanning electron microscopy,transmission electron microscope,and X-ray diffraction analyses.The microhardness,joint efficiency,and elongation at the fracture point of the AFS-welded AZ31B joint were 80 HV,101%,and 8.9%,respectively.These values are higher than those obtained for the FS-welded AZ31 joint in previous studies.The corrosion resistance of the AFS-welded AZ31B joint,evaluated via hydrogen evolution measurements and potentiodynamic polarization tests,was enhanced to 55%relative to the FS-welded AZ31B joint.

Clinical efficacy of combined topical 0.05%cyclosporine A and 0.1%sodium hyaluronate in the dry eyes with meibomian gland dysfunction

AIM: To investigate the efficacy of combined topical 0.05% cyclosporine A(CsA; Restasis~?, Allergan pharmaceuticals, USA) and 0.1% sodium hyaluronate treatment in dry eyes with meibomian gland dysfunction(MGD).METHODS: In a retrospective analysis, 53 patients(106 eyes) with MGD were enrolled and performed lid warm massage for 10 min daily and be instilled preservative free sodium hyaluronate 0.1% eye drops 4 times daily. Patients were divided into subjects treated with topical 0.05% CsA and preservative free sodium hyaluronate vehicle(experimental group, n=74 eyes) and subjects treated with the preservative free sodium hyaluronate vehicle(control group, n=32 eyes). They were evaluated at baseline and 1, 2, and 3 mo for subjective symptoms and objective signs including tear film break-up time(t BUT), Schirmer test, corneal staining(CS) score, lid margin telangiectasia(LMT), meibomian gland secretion(MGS), and conjunctival injection(CI).RESULTS: In the short-term treatment, the experimental group showed a statistically significant improvement in the ocular surface disease index(OSDI; P<0.001), tBUT(P=0.004), Schirmer test score(P=0.008) and LMT(P=0.021) by repeated measure ANOVA. Additionally, mean changes from baseline in OSDI(P<0.001), tBUT(P=0.001), Schirmer test score(P=0.029), CS score(P=0.047), LMT(P=0.002), CI(P=0.030) were improved better in the experimental group than in the control group at 3 mo. However, there was no significant difference between the two groups in MGS(P=0.67).CONCLUSION: In dry eyes with MGD, 0.05% CsA improves the tear film stability as well as subjective ocular discomfort, and is effective in controlling lid margin inflammation.

Evaluation of anatomical considerations in the posterior maxillae for sinus augmentation

The edentulous posterior maxilla is considered a clinical challenge during dental implant treatment for many dental practitioners. This is because its insufficient bone quality, deficient alveolar ridge, spiny ridges, undercuts, and sinus pneumatization are often encountered after tooth loss. To overcome these problems, several approaches have been developed and are currently used, including sinus augmentation and bone augmentation. Today, two main procedures of sinus floor elevation for dental implant placement are in use: a two-stage technique using the lateral window approach, and a onestage technique using a lateral or a crestal approach. In this study, we deal with the anatomic relations ofthe structures of the maxillary sinus during sinus augmentation. These anatomical findings can help in complications and potential injuries of the maxillary sinus procedures. It can be suggested that pre-operative evaluation is helpful for diagnosis and treatment planning and minimizing complication during the surgery.

Comparison of cytotoxicity and wound healing effect of carboxymethylcellulose and hyaluronic acid on human corneal epithelial cells

AIM: To investigate the cytotoxic effect on human corneal epithelial cells(HCECs) and the ability to faciliate corneal epithelial wound healing of carboxymethylcellulose(CMC) and hyaluronic acid(HA).METHODS: HCECs were exposed to 0.5% CMC(Refresh plus, Allergan, Irvine, California, USA) and 0.1% and 0.3%HA(Kynex , Alcon, Seoul, Korea, and Hyalein mini,Santen, Osaka, Japan) for the period of 30 min, and 4, 12,and 24 h. Methyl thiazolyl tetrazoiun(MTT)-based calorimetric assay was performed to assess the metabolic activity of cellular proliferation and lactate dehydrogenase(LDH) leakage assay to assess the cytotoxicity. apoptotic response was evaluated with flow cytometric analysis and fluorescence staining with Annexin V and propiodium iodide. Cellular morphology was evaluated by inverted phase-contrast light microscopy and electron microscopy. The wound widths were measured 24 h after confluent HCECs were scratch wounded.RESULTS: The inhibitory effect of human corneal epithelial proliferation and cytotoxicity showed the time-dependent response but no significant effect. Apoptosis developed in flow cytometry and apoptotic cells weredemonstrated in fluorescent micrograph. The damaged HCECs were detached from the bottom of the dish and showed the well-developed vacuole formations. Both CMC and HA stimulated reepithehlialization of HCECs scratched, which were more observed in CMC.CONCLUSION: CMC and HA, used in artificial tear formulation, could be utilized without any significant toxic effect on HCECs. Both significantly stimulated HCEC reepithelialization of corneal wounds.

Early expression of mannose-binding lectin 2 during Aspergillus fumigatus infection in human corneal epithelial cells

AIM: To evaluate the early expression of mannose-binding lectin 2(MBL2) in human corneal epithelial cells(HCECs) infected by Aspergillus fumigatus(AF).METHODS: HCECs cultured in vitro with AF antigens and sampled at 0, 0.5, 1, 2, 4, 6 and 8h. The expression of MBL2 m RNA was evaluated by semiquantitative reverse transcription-polymerase chain reaction(RT-PCR). The expression of MBL2 protein in supernatant fluid was shown by enzyme linked immunosorbent assay(ELISA). MBL2 protein in HCECs was detected by immunocytochemistry at 0 and 24 h.RESULTS: MBL2 m RNA and protein are expressed in normal HCECs. The expression of MBL2 m RNA and protein in supernatant fluid begin to increase after being stimulated with AF antigens. The most significantly peak of MBL2 m RNA is in 2h. The protein of MBL2 in supernatant fluid decrease gradually after 0.5h. The protein in HCECs expression increase after stimulation of24 h.· CONCLUSION: MBL2 receptor expressed in normal HCECs in vitro. The stimulation by AF antigens can increase the early expression of it.

Effect of Asiasari radix on osteoblastic differentiation of stem cells derived from gingiva

OBJECTIVE: To examine the dose-dependent impact of Asiasari Radix(A. radix) on the cell viability,differentiation and mineralization of stem cells derived from gingiva.METHODS: Stem cells that were derived from gingiva were grown in the presence of A. radix at final concentrations that ranged from 0.001 to 10 μg/m L. The morphology of the cells was viewed under an inverted microscope and the analysis of cell proliferation was performed by using Cell Counting Kit-8(CCK-8) on day 1. The alkaline phosphatase activity test was used to assess differentiation and Alizarin red S staining was used to assess mineralization of treated cells.RESULTS: The control group showed spindleshaped, fibroblast-like morphology and the shapesof the cells in 0.001, 0.01, 0.1, 1 and 10 μg/mL of A.radix were similar to that of the control group at day 1. The cultures growing in the presence of0.001 μg/m L of A. radix at day 1 showed an increase in the CCK-8 value(P < 0.05). Cultures growing in the presence of 0.001 μg/m L of A. radix presented the highest value for alkaline phosphatase activity(P > 0.05). Mineralized extracellular deposits were observed after Alizarin Red S staining and the cultures grown in the presence of 0.001 μg/m L of A. radix showed the highest value for quantitative results for bound dye(P < 0.05).CONCLUSION: Within the limits of this study, A. radix influenced the proliferation of stem cells derived from the gingiva and low concentrations of A.radix might enhance osteogenic differentiation of the stem cells.