Poliolefin modifiye bitümün Marshall stabilitesi üzerindeki etkisi

It is possible to improve the performance of the hot mix asphalt (HMA) by improving the properties of the materials (aggregate, bitumen) used in the HMA or by the addition of some special materials. In this study; polypropylene (PP) and high density polyethylene (HDPE) waste plastics were co–pyrolyzed at a temperature range of 300–350 °C. 2, 4, 5 and 6 % modified bitumen were made by using the solid product (char–additive) obtained from co–pyrolysis and pure 50/70 penetration grade bitumen. RV (rotational viscometer) tests were applied to pure and modified bitumens at different temperatures (60–165 °C) and the optimum rate of PP–HDPE additive was determined to be 5 %. Then; two different HMA sample series were prepared with Marshall apparatus using pure and 5 % PP–HDPE modified bitumen. For Marshall Mix design, sample series were formed at bitumen rates 3.5; 4; 4.5; 5 and 5.5 % and four HMA samples were produced at each bitumen rate. The samples were weighed in water, dry and saturated surface–dry. The heights of the samples were measured and the Marshall stability and flow values were determined by applying a load at a certain speed (50 mm/min). As a result; compared to the pure HMA, it was observed that the Marshall stability of the modified HMA increases between about 8.5 and 13 %.Bitümlü sıcak karışımda (BSK) kullanılan malzemelerin (agrega, bitüm) özelliklerini iyileştirerek veya bazı özel malzemeler ilave ederek, BSK’nın performansını artırmak mümkündür. Bu çalışmada; polipropilen (PP) ve yüksek yoğunluklu polietilen (YYPE) atık plastikleri 300–350 °C sıcaklık aralığında birlikte piroliz edildi. Pirolizden elde edilen katı ürün (çar–katkı maddesi) ve saf 50/70 penetrasyon dereceli bitüm kullanılarak, % 2, 4, 5 ve 6 oranlarında modifiye bitümler yapıldı. Saf ve modifiye bitümlere, farklı sıcaklıklarda (60–165 °C) RV (dönel viskozimetre) testleri uygulandı ve PP–YYPE katkısının optimum oranı % 5 olarak belirlendi. Sonra; saf ve % 5 PP–YYPE modifiye bitüm kullanılarak, Marshall aparatı ile iki farklı BSK numune serisi hazırlandı. Marshall karışım tasarımı için, % 3,5; 4,0; 4,5; 5,0 ve 5,5 bitüm oranlarında numune serileri oluşturuldu ve her bir bitüm oranında 4 BSK numunesi üretildi. Kuru ve doygun yüzey–kuru olarak tartılan numuneler, su içinde tartıldı. Numunelerin yükseklikleri ölçüldü ve belirli bir hızda (50 mm/dakika) bir yük uygulanarak, Marshall stabilite ve akma değerleri belirlendi. Sonuç olarak; saf BSK ile karşılaştırıldığında, modifiye BSK'nın Marshall stabilitesinin yaklaşık % 8,5 ila 13,0 arasında arttığı gözlenmiştir

Surgical Aortic Valve Replacement with Concomitant Aortic Surgery in Patients with Purely Bicuspid Aortic Valve and Associated Aortopathy

The bicuspid aortic valve (BAV) is the most common congenital cardiac malformation associated with aortopathy. The current study provides surgical clinical data on the patient characteristics and long-term survival of this less common adult purely BAV population undergoing surgical aortic valve replacement (SAVR) with concomitant aortic surgery. Adult patients with purely BAV who underwent SAVR and concomitant aortic surgery were included. Prevalence, predictors of survival, and outcomes for this patient population were analyzed. A total of 48 patients (mean age 58.7 ± 13.2 years, 33% female) with purely BAV underwent SAVR and concomitant aortic surgery between 1987 and 2016. The majority (62%) of the patients had pure aortic stenosis (AS). A total of 12 patients died. Survival was 92%, 73%, and 69% at 1, 5, and 20 years of follow-up. At 15 years of follow-up, the survival was close to that of the Dutch population, with a relative survival of 77%. Adult patients with a purely bicuspid aortic valve morphology undergoing SAVR and concomitant aortic root and/or ascending aorta present with excellent survival

Comparative study of male and female patients undergoing surgical aortic valve replacement

BACKGROUND: Sex does have an effect on disease perception and outcomes after cardiac surgery. OBJECTIVES: The aim of this study was to quantify the differences in cardiovascular risk profiles within an age-matched cohort and assess the long-term survival differences in males and females who underwent surgical aortic valve replacement (SAVR) with or without concomitant coronary artery bypass surgery. METHODS: All-comers patients who underwent SAVR with or without coronary artery bypass surgery were included. Characteristics, clinical features and survival up to 30 years were compared between female and male patients. Propensity matching and age matching using propensity scores were used to compare both groups. RESULTS: During the total study period between 1987 and 2017, there were 3462 patients {mean age 66.8 [standard deviation (SD): 11.1] years, 37.1% female} who underwent SAVR with or without coronary artery bypass surgery at our institution. In general, female patients were older than male patients (69.1 (SD: 10.3) versus 65.5 (SD: 11.3), respectively). In the age-matched cohort, female patients were less likely to have multiple comorbidities and undergo concomitant coronary artery bypass surgery. Twenty-year survival following the index procedure was higher in age-matched female patients (27.1%) compared to male patients (24.4%) in the overall cohort (P = 0.018). CONCLUSIONS: Substantial sex differences in cardiovascular risk profile exist. However, when SAVR with or without coronary artery bypass surgery is performed, extended long-term mortality is comparable between males and females. More research regarding sex-dimorphic mechanisms of aortic stenosis and coronary atherosclerosis would promote more awareness in terms of sex-specific risk factors after cardiac surgery and contribute to more guided personalized surgery in the future.</p

Surgical Aortic Valve Replacement with Concomitant Aortic Surgery in Patients with Purely Bicuspid Aortic Valve and Associated Aortopathy

The bicuspid aortic valve (BAV) is the most common congenital cardiac malformation associated with aortopathy. The current study provides surgical clinical data on the patient characteristics and long-term survival of this less common adult purely BAV population undergoing surgical aortic valve replacement (SAVR) with concomitant aortic surgery. Adult patients with purely BAV who underwent SAVR and concomitant aortic surgery were included. Prevalence, predictors of survival, and outcomes for this patient population were analyzed. A total of 48 patients (mean age 58.7 ± 13.2 years, 33% female) with purely BAV underwent SAVR and concomitant aortic surgery between 1987 and 2016. The majority (62%) of the patients had pure aortic stenosis (AS). A total of 12 patients died. Survival was 92%, 73%, and 69% at 1, 5, and 20 years of follow-up. At 15 years of follow-up, the survival was close to that of the Dutch population, with a relative survival of 77%. Adult patients with a purely bicuspid aortic valve morphology undergoing SAVR and concomitant aortic root and/or ascending aorta present with excellent survival

Comparative study of male and female patients undergoing surgical aortic valve replacement

BACKGROUND: Sex does have an effect on disease perception and outcomes after cardiac surgery. OBJECTIVES: The aim of this study was to quantify the differences in cardiovascular risk profiles within an age-matched cohort and assess the long-term survival differences in males and females who underwent surgical aortic valve replacement (SAVR) with or without concomitant coronary artery bypass surgery. METHODS: All-comers patients who underwent SAVR with or without coronary artery bypass surgery were included. Characteristics, clinical features and survival up to 30 years were compared between female and male patients. Propensity matching and age matching using propensity scores were used to compare both groups. RESULTS: During the total study period between 1987 and 2017, there were 3462 patients {mean age 66.8 [standard deviation (SD): 11.1] years, 37.1% female} who underwent SAVR with or without coronary artery bypass surgery at our institution. In general, female patients were older than male patients (69.1 (SD: 10.3) versus 65.5 (SD: 11.3), respectively). In the age-matched cohort, female patients were less likely to have multiple comorbidities and undergo concomitant coronary artery bypass surgery. Twenty-year survival following the index procedure was higher in age-matched female patients (27.1%) compared to male patients (24.4%) in the overall cohort (P = 0.018). CONCLUSIONS: Substantial sex differences in cardiovascular risk profile exist. However, when SAVR with or without coronary artery bypass surgery is performed, extended long-term mortality is comparable between males and females. More research regarding sex-dimorphic mechanisms of aortic stenosis and coronary atherosclerosis would promote more awareness in terms of sex-specific risk factors after cardiac surgery and contribute to more guided personalized surgery in the future.</p