Effect of bolt configurations on stiffness for steel-wood-steel connection loaded parallel to grain for softwoods in Malaysia

Steel-wood-steel connection is widely seen in many applications, such as timber structures. The stiffness of steel-wood-steel connection loaded parallel to grain for softwoods originated from Malaysia was investigated in this study. Numerical models have been developed in ABAQUS to study the stiffness connection. Softwoods of Damar Minyak and Podo have been selected in this analysis. The comprehensive study focused on the effect of bolt configurations on stiffness. Numerical analysis is carried out and the developed model has been validated with the previous study. Further investigations have been made by using the validated model. From this model, numerical analysis of the stiffness values have been made for various bolt configurations, including bolt diameter, end distance, bolt spacing, number of rows and bolts and edge distance. The result shows that the stiffness of bolted timber connections for softwood depends on the bolt diameter, number of rows and bolts, end distance and edge distance. Based on the result, stiffness increased as the diameter of the bolt, end distance, number of rows and bolts and edge distance increased. It is also discovered that the stiffness equation in Eurocode 5 (EC5) is inadequate as the equation only considered parameters which are wood density and bolt diameter. Other connection parameters such as geometry are not considered in the EC5 equation

The Stiffness of Steel-Wood-Steel Connection Loaded Parallel to the Grain

In Eurocode 5, the stiffness equation for bolted steel-wood-steel is stated as a function of wood density and fastener diameter only. In this research, an experimental study on various configurations of tested bolted steel-wood-steel (SWS) connections has been undertaken to predict the initial stiffness of each connection. In order to validate the Eurocode 5 stiffness equation, tests on 50 timber specimens (40 glued laminated timbers and 10 laminated veneer lumbers (LVL)) with steel plates were undertaken. The number of bolts was kept similar and the connector diameter, timber thickness, and wood density were varied. The results obtained in the experimental tests are compared with those obtained from the Eurocode 5 stiffness equation. From the analysis, it is signified that the stiffness equation specified in Eurocode 5 for bolted SWS connections does not adequately predict the initial stiffness. The results from Eurocode 5 stiffness equation are very far from the experimental values. The ratio of stiffness equation to experimental results ranges from 3.48 to 4.20, with the average at 3.77, where the equation overpredicted the experimental stiffness value for the connection. There is a need to consider or incorporated other parameters such as geometric configurations in Eurocode 5 stiffness equation to improve the ratio with the experimental data

Characterization and Mechanical Proprieties of New TiMo Alloys Used for Medical Applications

Ti-based alloys are accessible for use in the human body due to their good mechanical properties, corrosion resistance, and biocompatibilities. These main properties of alloys are important criteria for choosing biomedical implants for human bones or for other kinds of applications in general medicine. This paper presents a comparison of four new Ti-based alloys desired to satisfy various requirements for biomedical implants. The materials were prepared with recipes for two new system alloys, TiMoZrTa (TMZT) and TiMoSi (TMS), alloys with nontoxic elements. The presented research contains microstructure images, indentation tests, Vickers hardness, XRD, and corrosion resistance, showing better characteristics than most commercial products used as implants (Young’s modulus closer to the human bone)

Biomimetic Deposition of Hydroxyapatite Layer on Titanium Alloys

Over the last decade, researchers have been concerned with improving metallic biomaterials with proper and suitable properties for the human body. Ti-based alloys are widely used in the medical field for their good mechanical properties, corrosion resistance and biocompatibility. The TiMoZrTa system (TMZT) evidenced adequate mechanical properties, was closer to the human bone, and had a good biocompatibility. In order to highlight the osseointegration of the implants, a layer of hydroxyapatite (HA) was deposited using a biomimetic method, which simulates the natural growth of the bone. The coatings were examined by scanning electron microscopy (SEM), X-ray diffraction (XRD), micro indentation tests and contact angle. The data obtained show that the layer deposited on TiMoZrTa (TMZT) support is hydroxyapatite. Modifying the surface of titanium alloys represents a viable solution for increasing the osseointegration of materials used as implants. The studied coatings demonstrate a positive potential for use as dental and orthopedic implants

The Influence of Radiotherapy on the Function of the Left and Right Ventricles in Relation to the Radiation Dose Administered to the Left Anterior Descending Coronary Artery—From a Cardiologist’s Point of View

The aim of this study was to assess the effects of radiotherapy involving the heart on LV and RV function using modern speckle-tracking echocardiography (STE), and in relation to the radiation dose applied to the LAD. This retrospective, single-centre study included 12 patients after a median of 51 months after irradiation for mediastinal lymphoma, in whom we were able to delineate the LAD. Correlations between doses of ionising radiation and echocardiographic parameters reflecting the systolic function of the LV and RV were analysed. The median irradiation dose delivered to the whole heart was 16.4 Gy (0.5–36.2 Gy), and to the LAD it was 15.1 Gy (0.3–35.3 Gy). LV longitudinal strain (LS) was impaired in the anteroseptal and anterior walls. Parameters reflecting RV function were normal, with the exception of RV myocardial performance index (RIMP). Significant correlations were found between the median dose to the LAD and LV global LS (rho = 0.6468, p = 0.034), the maximum dose to the LAD and LV anterior LS (rho = 0.6046, p = 0.049), the median and the mean dose to the whole heart and LV anterior LS (R = 0.772, p = 0.009 and rho = 0.7676, p = 0.01, respectively), and the total irradiation dose and RIMP (rho = 0.5981, p = 0.04). The calculation of irradiation doses allows the identification of patients at risk of cardiac dysfunction detected by modern STE

Technique of the transcervical-subxiphoid-videothoracoscopic maximal thymectomy

Background: The aim of this study is to present the new technique of transcervical-subxiphoid-videothoracoscopic "maximal"thymectomy introduced by the authors of this study for myasthenia gravis. Materials and Methods: Two hundred and sixteen patients with Osserman scores ranging from I-III were operated on from 1/9/2000 to 31/12/2006 for this study. The operation was performed through four incisions: a transverse 5-8 cm incision in the neck, a 4-6 cm subxiphoid incision and two 1 cm incisions for videothoracoscopic (VTS) ports. The cervical part of the procedure was performed with an open technique while the intrathoracic part was performed using a video-assisted thoracoscopic surgical (VATS) technique. The whole thymus with the surrounding fatty tissue containing possible ectopic foci of the thymic tissue was removed. Such an operation can be performed by one surgical team (the one team approach) or by two teams working simultaneously (two team approach). The early and late results as well as the incidence and localization of ectopic thymic foci have been presented in this report. Results: There were 216 patients in this study of which 178 were women and 38 were men. The ages of the patients ranged from 11 to 69 years (mean 29.7 years). The duration of myasthenia was 2-180 months (mean 28.3 months). Osserman scores were in the range of I-III. Almost 27% of the patients were taking steroids or immunosuppressive drugs preoperatively. The mean operative time was 201.5 min (120-330 min) for a one-team approach and it was 146 (95-210 min) for a two-team approach (P < 0.05). While there was no postoperative mortality, the postoperative morbidity was 12%. The incidence of ectopic thymic foci was 68.4%. The rates of complete remission after one, two, three, four and five years of follow-up were 26.3, 36.5, 42.9, 46.8 and 50.2%, respectively. Conclusion: Transcervical-subxiphoid-VTS maximal thymectomy is a complete and highly effective treatment modality for myasthenia gravis. The need for sternotomy is avoided while the completeness of the operation is retained

Technique of the transcervical-subxiphoid-videothoracoscopic maximal thymectomy

<b>Background</b>: The aim of this study is to present the new technique of transcervical-subxiphoid-videothoracoscopic "maximal"thymectomy introduced by the authors of this study for myasthenia gravis. <b>Materials and Methods</b>: Two hundred and sixteen patients with Osserman scores ranging from I-III were operated on from 1/9/2000 to 31/12/2006 for this study. The operation was performed through four incisions: a transverse 5-8 cm incision in the neck, a 4-6 cm subxiphoid incision and two 1 cm incisions for videothoracoscopic (VTS) ports. The cervical part of the procedure was performed with an open technique while the intrathoracic part was performed using a video-assisted thoracoscopic surgical (VATS) technique. The whole thymus with the surrounding fatty tissue containing possible ectopic foci of the thymic tissue was removed. Such an operation can be performed by one surgical team (the one team approach) or by two teams working simultaneously (two team approach). The early and late results as well as the incidence and localization of ectopic thymic foci have been presented in this report. <b>Results</b>: There were 216 patients in this study of which 178 were women and 38 were men. The ages of the patients ranged from 11 to 69 years (mean 29.7 years). The duration of myasthenia was 2-180 months (mean 28.3 months). Osserman scores were in the range of I-III. Almost 27&#x0025; of the patients were taking steroids or immunosuppressive drugs preoperatively. The mean operative time was 201.5 min (120-330 min) for a one-team approach and it was 146 (95-210 min) for a two-team approach (<i>P</i> &lt; 0.05). While there was no postoperative mortality, the postoperative morbidity was 12&#x0025;. The incidence of ectopic thymic foci was 68.4&#x0025;. The rates of complete remission after one, two, three, four and five years of follow-up were 26.3, 36.5, 42.9, 46.8 and 50.2&#x0025;, respectively. <b>Conclusion</b>: Transcervical-subxiphoid-VTS maximal thymectomy is a complete and highly effective treatment modality for myasthenia gravis. The need for sternotomy is avoided while the completeness of the operation is retained

Technique of the transcervical-subxiphoid-videothoracoscopic maximal thymectomy

BACKGROUND: The aim of this study is to present the new technique of transcervical-subxiphoid-videothoracoscopic “maximal”thymectomy introduced by the authors of this study for myasthenia gravis. MATERIALS AND METHODS: Two hundred and sixteen patients with Osserman scores ranging from I–III were operated on from 1/9/2000 to 31/12/2006 for this study. The operation was performed through four incisions: a transverse 5–8 cm incision in the neck, a 4–6 cm subxiphoid incision and two 1 cm incisions for videothoracoscopic (VTS) ports. The cervical part of the procedure was performed with an open technique while the intrathoracic part was performed using a video assisted thoracoscopic surgical (VATS) technique. The whole thymus with the surrounding fatty tissue containing possible ectopic foci of the thymic tissue was removed. Such an operation can be performed by one surgical team (the one team approach) or by two teams working simultaneously (two team approach). The early and late results as well as the incidence and localization of ectopic thymic foci have been presented in this report. RESULTS: There were 216 patients in this study of which 178 were women and 38 were men. The ages of the patients ranged from 11 to 69 years (mean 29.7 years). The duration of myasthenia was 2–180 months (mean 28.3 months). Osserman scores were in the range of I–III. Almost 27% of the patients were taking steroids or immunosuppressive drugs preoperatively. The mean operative time was 201.5 min (120–330 min) for a one-team approach and it was 146 (95–210 min) for a two-team approach (P < 0.05). While there was no postoperative mortality, the postoperative morbidity was 12%. The incidence of ectopic thymic foci was 68.4%. The rates of complete remission after one, two, three, four and five years of follow-up were 26.3, 36.5, 42.9, 46.8 and 50.2%, respectively. CONCLUSION: Transcervical-subxiphoid-VTS maximal thymectomy is a complete and highly effective treatment modality for myasthenia gravis. The need for sternotomy is avoided while the completeness of the operation is retained

Effect of bolt configurations on stiffness for steel-wood-steel connection loaded parallel to grain for softwoods in Malaysia

Steel-wood-steel connection is widely seen in many applications, such as timber structures. The stiffness of steel-wood-steel connection loaded parallel to grain for softwoods originated from Malaysia was investigated in this study. Numerical models have been developed in ABAQUS to study the stiffness connection. Softwoods of Damar Minyak and Podo have been selected in this analysis. The comprehensive study focused on the effect of bolt configurations on stiffness. Numerical analysis is carried out and the developed model has been validated with the previous study. Further investigations have been made by using the validated model. From this model, numerical analysis of the stiffness values have been made for various bolt configurations, including bolt diameter, end distance, bolt spacing, number of rows and bolts and edge distance. The result shows that the stiffness of bolted timber connections for softwood depends on the bolt diameter, number of rows and bolts, end distance and edge distance. Based on the result, stiffness increased as the diameter of the bolt, end distance, number of rows and bolts and edge distance increased. It is also discovered that the stiffness equation in Eurocode 5 (EC5) is inadequate as the equation only considered parameters which are wood density and bolt diameter. Other connection parameters such as geometry are not considered in the EC5 equation