Investigation of Wear Behavior of Particle Reinforced AL/B4C Composites under Different Sintering Conditions

In this study, the effects of different sintering conditions of boron carbide reinforced to aluminum matrix powder on microstructure, density and wear resistance by a mechanical alloying method were researched. Powders produced by mechanical alloying for eight hours at the atrial shaft were compressed with a cold isostatic press die under 350 MPa to obtain cylindrical composite specimens. The raw samples were sintered in high purity argon at 600, 625, 650 °C for 90 minutes. The wear behavior of the Al/B4C metal matrix composite was studied using a pin-on-disk wear tester. Under favorable conditions, it has been observed that reinforced boron carbide wear can be reduced by more than two decades. Various investigations have been made to relate this improved wear performance to reinforcement ratios. Aluminum abrasion test results showed that different types of abrasion occurred and that the abrasion resistance was increased by the change of the bubble rate. In the experimental studies that were carried out, it was observed that wear resistance increased with the proportion of boron carbide reinforced directly by the weight, and especially with a 15% B4C ratio depending on the increased reinforcement ratio

Çok Duvarlı Karbon Nanotüp Takviyeli Düzenli/ Düzensiz Şekilli Ti-6Al-4V Kompozitlerin Aşınma Davranışlarının İncelenmesi

Bu çalışmada toz metalurjisinde yaygın olarak kullanılmakta olan mekanik alaşımlama yöntemi ile düzenli ve düzensiz şekilli Ti-6Al-4V tozlara farklı oranlarda ilave edilen çok duvarlı karbon nanotüp (ÇDKNT) tozlarının, farklı üretim şartları ve sinterleme ortamında üretilmesinin mikroyapı, yoğunluk ve aşınma davranışları incelenmiştir. Mekanik olarak karıştırılan kompozit tozlar, tek eksenli pres yardımı ile 100 MPa basınç altında sıkıştırılarak, silindirik kompozit numuneler elde edilmiştir. Elde edilen silindirik numuneler, 1200°C'de 120 dakika süre (10-3 mbar) vakum ve Argon (Ar) ortamında sinterlenmiştir. Üretilmiş olan kompozitlerin aşınma davranışları, pin-on-disk aşınma test cihazı kullanılarak incelenmiştir. Uygun koşullar altında çok duvarlı karbon nanotüp takviyeli kompozit malzemelerin aşınma oranları sırasıyla aynı mesafede (mm3/Nm), takviyesiz Ti-6Al-4V’de 9.10-8, 5.10-8, 3.10-9, 3.10-8, 2.10-8, 1,87.10-8 azaldığı görülmüştür. Geliştirilen aşınma özelliklerine ilave olarak, ÇDKNT oranlarının detaylandırılması ile ilgili çalışmalar yürütülmüştür. Aşınma test sonuçları, üretilmiş olan kompozit malzemeden Ti-6Al-4V aşınma modlarına geçişin pozitif ilerleme gösterdiği tespit edilmiştir. Yapılan bu çalışmada, aşınma direncinin, direkt hacimce ilave edilen % v/v ÇDKNT oranına göre aynı ağırlıkta (Nm/mm3) sırasıyla, takviyesiz Ti-6Al-4V’de 1.107, 1,8.107, 2,7.107, 2,82.107, 3,35.107, 5,4.107 azaldığı görülmüştür. Artan takviye ÇDKNT oranı ile birlikte aşınma özelliklerinin iyileştiği sonucu elde edilmiştir

Development and Design and Heat Treatment of Production, Storage and Mine Drilling Pipes in Petroleum and Geothermal Industries

In this study, sequential and different temperature heat treatments were applied to steels after austenating heat treatment applied to different AISI steel types. The effects of tempering heat treatment applied on the mechanical properties of the steel after quenching were investigated. The production of prototypes of the materials to be used in the drilling industry and the improvement of the properties of the drilling pipes used in the geothermal, petroleum, storage and mining sectors by thermal processes determined according to the standards have been realized. Different heat treatments have been applied to the materials in AISI standards provided by considering the desired material properties of the drill pipes. In order to improve the mechanical properties, the heat treatment process was determined and applied by a wide literature review. The prototypes of the drill rods were produced in three different AISI standards (AISI 4130, AISI 4140). Seamless tubes are produced according to AISI 4340 and ductile, semi-ductile and brittle conditions. 946.4 MPa. In addition, corrosion tests showed significant corrosion resistance

THE EFFECTS OF FACE MASK USE DURING COVID-19 ON SPEECH COMPREHENSION IN GERIATRIC PATIENTS WITH HEARING LOSS WHO USE LIP-READING FOR COMMUNICATION: A PROSPECTIVE CROSS-SECTIONAL STUDY

Objective: Communication difficulties are considered the most significant consequence of hearing loss. This study aimed to determine whether surgical face masks, which have been mandatory throughout the COVID-19 pandemic, have an effect on speech comprehension scores in geriatric lip-reading patients with hearing loss and to raise awareness of the need for solutions to this problem. Materials and Method: Patients with moderate and higher sensorineural or mixed bilateral symmetrical hearing loss who stated that they lip-read to better understand during communication were included in the study. The patients’ speech comprehension scores were gathered while the audiologist wore a surgical mask and then a transparent mask, respectively. Results: Twelve (33,3%) of the patients were female, and 24 (66.7%) were male. The mean age of the patients was 66.64±1.53 years. The mean speech comprehension scores of the patients when the audiologist was wearing a surgical mask (38.25±14.33) and a transparent mask (67.81 ± 14.30), respectively, were compared. The surgical mask significantly affected speech comprehension scores, and the Cohen d value of the effect size was 2.06. As such, the surgical face mask had a great effect on these patients’ speech comprehension scores. Conclusions: In elderly lip-reading patients who suffer from hearing loss, seeing the lip movements of the speaker, especially in hospital applications, promotes more effective communication. Transparent face masks can be considered a solution. © 2022, Geriatrics Society. All rights reserved

One-stage operation for hydatid disease of lung and liver: Principles of treatment

AbstractObjective: Hydatid disease is endemic in many countries throughout the world. Although we do not have exact figures, the disease is prevalent in Turkey. A considerable number of patients have additional liver cysts as well. In this study we reviewed our experience with hydatid disease of the lung and liver and discussed the principles of treatment. Methods: From 1971 to 1999, 2509 patients with pulmonary hydatidosis were referred to us, and 485 of them had concomitant liver cysts. Of these, 405 patients had cysts located on the dome of the liver, and they were operated on with phrenotomy through a right thoracotomy. Eighty patients who were found to have concomitant liver cysts in the lower part of the liver were referred to general surgery for a laparotomy. Results: Hydatid cysts located in the lungs were managed by means of cystotomy and capitonnage. For liver cysts, cystotomy and inversion of the cavity with sutures was the surgical method of choice, and a drain was left in place. In case of multiple cysts in the liver, needle aspiration was preferred. Twelve major complications, including excessive biliary drainage and bronchobiliary fistula, occurred in these patients. Conclusions: We believe that management of pulmonary and hepatic cysts simultaneously through the thoracic route is convenient and should be encouraged in patients because this prevents a second operation. Needle aspiration can be applied only for liver cysts. It is absolutely contraindicated in lung hydatid cysts.J Thorac Cardiovasc Surg 2002;124:1212-

The effect of gender on response to antithyroid drugs and risk of relapse after discontinuation of the antithyroid drugs in patients with Graves’ hyperthyroidism: a multicentre study

Introduction: The outcome of medical treatment in patients with Graves’ disease (GD) is generally difficult to predict. In this study, we examined the hypothesis that gender may affect the outcome of treatment with antithyroid drugs (ATDs). Material and methods: This is a retrospective multicentre study including 717 (514 female and 203 male) patients with the first episode of GD treated for at least 12 months. Patients were classified as relapse, poorly controlled (several episodes of hyperthyroidism followed by euthyroidism and rarely hypothyroidism, occurring after titration of ATDs), and remission. Results: During the mean follow-up time of 26.75 ± 21.25 months (between 1 and 120 months), 269 (37.5%), 176 (24.5%), and 272 (37.9%) patients experienced a relapse, a poorly controlled disease, and remained in remission, respectively. During the follow-up time, 223 (43.4%) of the female and only 49 (24%) of the male patients remained in remission. Relapse and poorly controlled disease (non-remitting GD) were more common in male compared to female patients with GD (hazard ratio 1.26, 95% CI: 1.03–1.53, p = 0.025). Graves’ disease in male patients tended to relapse earlier, and male patients tended to have larger goiter sizes at diagnosis as well. The smoking habit wasalso significantly more frequent in males compared to female patients with GD. Conclusion: Male patients with GD have a markedly higher frequency of relapse and poorly controlled disease, as compared to female patients. Larger goiter sizes and higher frequency of smoking may contribute to the higher frequency of relapse and poorly controlled disease in male patients.

The effect of sarcopenia on erlotinib therapy in patients with metastatic lung adenocarcinoma

Erlotinib, a tyrosine kinase inhibitor, has been shown to improve the survival of patients with epidermal growth factor receptor (EGFR)-mutated non-small cell lung cancer. Sarcopenia is a status with increasing importance in lung cancer, and it may predict a poor prognosis. We aimed to evaluate the impact of sarcopenia on erlotinib therapy and prognosis in patients with EGFR-mutated (exon 19 or 21 L858R) metastatic lung adenocarcinoma. Sarcopenia was defined as skeletal muscle index ≤39 cm2/m2 for women and ≤55 cm2/m2 for men. The patient characteristics, inflammation parameters, clinical and survival outcomes of the erlotinib therapy were examined according to sarcopenia status. We also analyzed the erlotinib treatment-related toxicity. Seventy-two patients were included in our retrospective study, and the mean age of the patients was 63.7 years. A total of 39 (54.2%) patients were diagnosed with sarcopenia. Patients with sarcopenia had a poor prognosis and had a shorter median progression-free survival (PFS) than patients without sarcopenia (10.5 months vs. 21.8 months, p=0.002). Sarcopenia (HR 2.08) and C-reactive protein > 6.5 mg/L (HR 2.57) were determined as independent poor prognostic factors for PFS of erlotinib therapy. Treatment-related toxicity occurred in 34.7% of patients treated with erlotinib, and sarcopenia did not significantly affect treatment-related toxicity. We also found that sarcopenia significantly affected the response to erlotinib. The expected survival outcomes may be low when erlotinib therapy is used in patients with sarcopenia and metastatic lung adenocarcinoma. This study showed that survival and clinical outcomes could be better predicted by detecting sarcopenia in patients with lung cancer using erlotinib

Nurses' perceptions of aids and obstacles to the provision of optimal end of life care in ICU

Contains fulltext : 172380.pdf (publisher's version ) (Open Access

Investigation of Mechanical Properties of Ti6Al4V Alloy Foams produced by Powder Metallurgy Method

In this study, it was aimed to production titanium alloy implants, which are widely used in the biomedical industry, as foamed materials under different mechanical alloying and sintering conditions using the powder metallurgy method Tİ6Al4V alloy is good mechanical properties, good biocompatibility properties and good corrosion resistance used as hard tissue replacements and implants. Similar mechanic properties with bone are expected from the implant to work coherently for long cycles of use and without any failure. Especially, elastic modulus of implant must be similar with bones, if not, some damages at bone surface and fallowing repeats of implant surgeries are reported. This situation has a destructive effect on health, finance, and comfort of the patient/user of the implant. In this study, powder metallurgy and space holder removal methods were used to produce porous Ti6Al4V specimens. Throughout the project study different space holder materials and binder agents were used. As weight percent, 20%, 30%, 40%, 60%, 70%, 80% porous specimens were pressed at uniaxial press machine, and sintered to the 850 ºC at argon atmosphere in furnace to reduce the oxidation to the level as low as possible. The E-Modulus values of the specimens reached the desired values with increasing porosity. It was obtained as 88 MPa in the specimen with 80% porosity, decreasing inversely proportionally, especially from the 60% porosity rate