THE EFFECT OF WEAR MECHANISM FOR PLASMA OXIDISED CP TI AND ITS ALLOYS ON TRIBOCORROSION PERFORMANCE

THE EFFECT OF WEAR MECHANISM FOR PLASMA OXIDISED CP TI AND ITS ALLOYS ON TRIBOCORROSION PERFORMANCEAbstract Commercially pure titanium (cp-Ti) and its alloys (Ti6Al4V, Ti45Nb, Ti6Al7Nb etc.) have an important use among biometallic materials. Recently developed alloying techniques and production methods have enabled many different titanium alloys to be used as biomaterials. Although harder and higher corrosion resistance than iron and its alloys, it is used as an invasive implant by applying various surface modifications to improve biodegradability performance. One of these processes is plasma oxidation process. With this process, corrosion resistance can be improved by obtaining more passive surfaces. There are many studies on these performance measurements in the literature. In this study, the effects of wear and corrosion mechanisms on the material in one cycle were investigated. Cp-Ti, Ti6Al4V and Ti45Nb were chosen as base materials. Samples were subjected to plasma oxidation for 600˚C-3 hours. Within the scope of this investigation, the adhesive wear mechanism on oxidized surfaces was compared with different types of abrasives, and its effect on corrosion performance was measured with the tribocorrosion test apparatus. Abrasion tests were carried out with two abrasive balls: tungsten carbide (WC) and silicon nitride (SiN) under 3 N load. Processes were carried out in two different media, dry and simulated body fluid (SBF). Potentiodynamic polarization scans were carried out using the scanning range of -0.28 V - 2 V in the presence of wear tests for tribocorrosion measurements. While abrasive wear mechanism is dominant in untreated samples, adhesive wear is at the forefront in coated samples. The effects that increase the corrosion resistance positively affected the performance of tribocorrosion. The high oxidation resistance of Ti and its alloys increased adhesive wear performance, and because of the higher corrosion resistance of Ti6Al4V and Ti45Nb, which were alloyed from these three material groups, their corrosion performance was higher than Cp-Ti.Keywords: Cp-Ti, Ti6Al4V, Ti45Nb, Plasma oxidation, Tribocorrosion

THE BIOMECHANICAL ANALYSIS FOR BIODEGRADABLE PURE MAGNESIUM BONE SCREWS UNDER THREE POINT BENDING AND TORSIONAL TEST

THE BIOMECHANICAL ANALYSIS FOR BIODEGRADABLE PURE MAGNESIUM BONE SCREWS UNDER THREE POINT BENDING AND TORSIONAL TESTAbstractRecently, magnesium and its alloys have been used as the raw material of degradable implants. In the orthopedic implant group, it is used in the production of medical tools due to its close modulus of elasticity and mechanical behavior suitable for bone tissue. In addition, magnesium is completely biodegradable both in biocompatible and living organisms. The purpose of using a degradable implant within the living organism is both to perform biomedical functions. It has become even more attractive to use the biodegradable magnesium screws due to the use of the temporary (non-biodegradable) implant in the living organism, the need for a secondary surgical operation to remove it from the body, and the increased risk of complications for the patient. However, the degradation times of magnesium screws; It is difficult to control the biological environment, the age and gender of the patients and the implant geometry Determination of the degradation stage is important for mechanical performance due to loss of mass and volume in the implant. Furthermore, loss of adhesion performance due to deterioration of bone screws weakens the mechanical properties of the implant system. Considering this feature of magnesium screws, pure magnesium screws of different origin were kept in phosphate buffer solution (pH = 7.4) for 1 day, 1,4,12 and 26 weeks. Then, three-point bending and torsion tests were performed according to ASTM F2502-11 standard to examine the mechanical properties of the screws. In the mechanical tests applied for both groups, when the three-point bending test and force-displacement curves were examined, it was observed that the mechanical properties of the 26th week decreased by about half compared to the 1st day. In the same way, when the torsion-torsion angle curves were examined in the torsion test, it was observed that the mechanical properties of the 26th week decreased for both groups.Keywords: Pure Magnesium, Biodegradation, Bone Screws, Three-Point Bending Test, Torsion Test

Histopathological effects on kidney of diclofenac potassium and diazepam used in an experimental epilepsy model

Aim: To investigate the effects of diazepam, which has anticonvulsant and anxiolytic effects, and diclofenac potassium, which has anti-inflammatory, analgesic and antipyretic effects, on rat kidney tissue, used in an experimental epilepsy model. Methods: 32 Wistar albino rats (2-4 months old, 200-250 gr) were used in the study. The rats were grouped in four as 8 rats in each group: Epilepsy, Epilepsy + Diazepam, Epilepsy + Diclofenac potassium, Epilepsy + Diazepam + Diclofenac potassium. Epileptic seizure model was created with penicillin (500.000 IU) injected intracortically under urethane anesthesia. 30 minutes later, diazepam (0.1 mg/kg) and diclofenac potassium (10 mg/kg) were administered intraperitoneally. At the end of the study, rat kidneys were removed and evaluated histopathologically in terms of inflammation, glomerular shrinkage, tubular dilatation, tubular epithelial thinning, desquame epithelium, brush epithelial loss, vacuolization, hemorrhage and congestion. Results: No difference was found between diazepam and diclofenac potassium in terms of vacuolization, glomerular shrinkage, tubular dilatation and hemorrhage. Inflammation, congestion and tubular epithelial thinning rate were found to be lower inEpilepsy + Diclofenac potassium and Epilepsy + Diazepam + Diclofenac potassium group when compared with Epilepsy + Diazepam group. While brush epithelial loss and desquame epithelial rate was found to be lowest in the epilepsy group, these parameters were not found to show a significant difference between drug groups. Conclusion: It was concluded that combined use of diazepam and diclofenac potassium in their effects on kidney are more useful than their single use

Comparison of Different Surgical Options in the Treatment of Pilonidal Disease: Retrospective Analysis of 175 Patients

Pilonidal sinus disease is a benign disorder with an unidentified etiology and is observed mainly in young adults. It is an important health problem because it causes work loss. Although various nonsurgical treatment options have been tried up to date, there is a consensus on surgical intervention to treat the disease today. The optimal surgical method should be simple, associated with short hospital stay and low recurrence rates. In this study, patients who have undergone different surgical treatment methods due to pilonidal disease were retrospectively analyzed. The medical records of 175 patients who were operated on between 2002 and 2005 at the General Surgery Departments of Gaziosmanpasa University Medical School and Bartin State Hospital for pilonidal disease were reviewed for treatment option, postoperative complications, hospitalization time, work-off periods, and recurrence rates. The patients consisted of 150 (85.3%) males with a mean age of 26.47 ± 7.78 years. Marsupialization was applied to 82 (46.9%), unroofing to 20 (14.7%), primary closure to 29 (16.6%), and Limberg flap to 44 (25.1%) patients. The longest hospitalization period of 3.61 ± 1.08 days was observed in the Limberg flap group. The longest return to work period (20.12 ± 5.1 days) was observed in the marsupialization group. Both differences were significant. The highest complication rate was observed among the primary closure group (31%) followed by the patients treated by Limberg flap technique (15.8%). In the primary closure group, infection was detected in five (17.2%) and wound dehiscence in four (13.8%) individuals. The highest complication rates (31.03%) and recurrences (13.8%) were observed in the primary closure group. Various operative methods utilized in the treatment of pilonidal disease are associated with a number of advantages and disadvantages. Postoperative complication rates of unroofing and marsupialization are low, but require long wound care. In our study, we did not observe any recurrence among the patients treated by unroofing, but experienced a high recurrence ratio among subjects treated by marsupialization. In addition, there were high complication rates in the primary closure and Limberg flap groups. So, the best option is to explain the advantages and disadvantages of the available surgical methods and respect the patient's decision

Aggressive Angiomyxoma: A Rare Tumor of Male Pelvic Cavity

Aggressive angiomyxoma is an uncommon, benign, slow-growing, and locally infiltrative soft tissue neoplasm which is located primarily in the genital region and pelviperineal interstitial tissue of female patient in the fourth decade of life. Its occurrence in male patients is even more unusual and commonly appears at a later age. The mainstay of treatment typically involves surgical excision with tumor-free margins, and despite complete resection, local recurrences are common. Here, an unusual case of aggressive angiomyxoma occurring in the pelvic region of a 55-year-old man and its treatment is discussed due to its rarity

Potential Growth: A Global Database

Potential growth—the rate of expansion an economy can sustain at full capacity and employment—is a critical driver of development progress. It is also a major input in the formulation of fiscal and monetary policies over the business cycle. This paper introduces the most comprehensive database to date, covering the nine most commonly used measures of potential growth for up to 173 countries over 1981-2021. Based on this database, the paper presents three findings. First, all measures of global potential growth show a steady and widespread decline over the past decade, with all the fundamental drivers of growth losing momentum over time. In 2011-21, potential growth was below its 2000-10 average in nearly all advanced economies and roughly 60 percent of emerging market and developing economies. Second, adverse events, such as the global financial crisis and the COVID-19 pandemic, contributed to the decline. At the country-level also, national recessions lowered potential growth even five years after their onset. Third, the persistent impact of recessions on potential growth operated through weaker growth of investment, employment, and productivity

Acute effect of phosphodiesterase type 5 inhibitor on serum oxidative status and prolidase activities in men with erectile dysfunction

OBJECTIVES: To investigate the acute effect of phosphodiesterase type 5 (PDE5) inhibitor on erectile dysfunction by evaluating serum oxidative status and prolidase activity. METHODS: Serum samples of 36 patients with erectile dysfunction and 30 control cases were analyzed for total antioxidant status, total oxidant status, and prolidase activity, before and after the administration of tadalafil citrate. RESULTS: Before and after tadalafil citrate administration, serum total antioxidant status, total oxidant status, and prolidase were 1.1+0.0 vs. 1.6 + 0.0 umol H2O2 Eq/L, 10.3+1.1 vs. 6.9 + 1.2 umol H2O2 Eq/L, and 236.4+19.5 vs. 228.2 + 19.2 U/L, respectively (

Lymphatic mapping and sentinel node biopsy in gynecological cancers: a critical review of the literature

Although it does not have a long history of sentinel node evaluation (SLN) in female genital system cancers, there is a growing number of promising study results, despite the presence of some aspects that need to be considered and developed. It has been most commonly used in vulvar and uterine cervivcal cancer in gynecological oncology. According to these studies, almost all of which are prospective, particularly in cases where Technetium-labeled nanocolloid is used, sentinel node detection rate sensitivity and specificity has been reported to be 100%, except for a few cases. In the studies on cervical cancer, sentinel node detection rates have been reported around 80–86%, a little lower than those in vulva cancer, and negative predictive value has been reported about 99%. It is relatively new in endometrial cancer, where its detection rate varies between 50 and 80%. Studies about vulvar melanoma and vaginal cancers are generally case reports. Although it has not been supported with multicenter randomized and controlled studies including larger case series, study results reported by various centers around the world are harmonious and mutually supportive particularly in vulva cancer, and cervix cancer. Even though it does not seem possible to replace the traditional approaches in these two cancers, it is still a serious alternative for the future. We believe that it is important to increase and support the studies that will strengthen the weaknesses of the method, among which there are detection of micrometastases and increasing detection rates, and render it usable in routine clinical practice