Bleaching of Hemp (Cannabis Sativa L.) Fibers with Peracetic Acid for Textiles Industry Purposes

Görkem Gedik,Ozan Avinc 한국섬유공학회 2018 Fibers and polymers Vol.19 No.1

Hemp plant exhibits various eco-friendly properties and hemp fiber processing does not cause environmental damage, however, it is known that most chemical operations have a risk to interrupt a sustainable production. As stated in several studies, peracetic acid is an important environmental friendly bleaching agent when compared to its conventional competitors. In this study, hemp fabric was bleached with peracetic acid with exhaustion and padding methods. The effects of temperature, pH, process time, concentration on whiteness values were determined. The influences of bleaching processes were investigated via instrumental and imaging methods. Physical properties of the treated fibers were also tested. Besides peracetic acid, hydrogen peroxide bleaching was carried out for comparison. COD values of bleaching effluents wereanalyzed for selected samples. Higher whiteness values were obtained with exhaustion bleachings than pad-batch bleachings.Quite high whiteness values (up to 68.13 Stensby whiteness index) attained in peracetic acid without significant fiber damage.

Simultaneous Eco-friendly Bleaching and Retting Wastewater Treatment of Hemp Fiber with Ozone Application

Görkem Gedik,Yağmur Meltem Aydın Kızılkaya,Vedat Uyak,Ahmet Koluman 한국섬유공학회 2023 Fibers and polymers Vol.24 No.1

The main aim of this study was to reduce the biological load in the retting effluents by eliminating the microorganism and at the same time, to bleach hemp fibers in the retting liquor, with ozone treatment. In addition to prevention of the environmentalpollution, time, energy, water and chemical consumption decrease were targeted by the ozone bleaching of hemp fiber in the retting liquor. For this purpose, retting liquor was treated with ozone gas in different concentrations (5–25 g/h) anddurations (5–90 min) while hemp stems were still in it. The environmental impact was investigated by TOC (Total Organic Carbon), BOD (Biochemical Oxygen Demand) and COD (Chemical Oxygen Demand) measurements. Ozone applicationresulted in dramatic reductions on BOD and TOC values. Total bacteria count in the untreated retting liquor and ozonetreated samples was determined, up to 100% sanitation effect was achieved by ozone application. Whiteness degrees of the hemp fibers increased up to 72% with ozone application compared with the retted sample. The chemical compositions of the fibers were stated by chemical tests and oxidative damage related to ozone treatment was investigated. The lignin ratio was significantly reduced after ozone application. The results of the chemical tests were supported by FTIR measurements. The mechanical properties such as tenacity and elongation were analyzed with tensile tests. The crystallographic characteristics were investigated with XRD, the crystallinity index was increased with ozone treatment.

Successful surgical intervention in traumatic carotid artery thrombosis after a motor vehicle accident: a case report

Yiğit Görkem 대한외상학회 2023 大韓外傷學會誌 Vol.36 No.1

Blunt carotid artery injury can lead to impaired brain perfusion due to ischemic stroke and thromboembolic events. To reduce the risk of potential neurological complications, it is critical to determine the diagnosis and management protocol as quickly as possible after a detailed clinical examination. This report presents successful surgical treatment of a young male patient who developed a traumatic left common carotid artery thrombosis after a motor vehicle accident.

Load capacity of high-strength reinforced concrete slabs by yield line theory

Selçuk Emre Gӧrkem,Metin Hϋsem 사단법인 한국계산역학회 2013 Computers and Concrete, An International Journal Vol.12 No.6

The objective of this study is to determine whether or not the yield line theory, an effective method widely used for slabs made of ordinary concrete, can be used also for the reinforced concrete slabs made of high-strength concrete. Flexural behavior of simply supported slabs in three different sizes were investigated under concentrated load at mid-span. Additionally, behavior of high strength reinforced concrete slabs with 50 mm and 150 mm reinforcement spacings also studied. Failure loads, deflections, experimental and theoretical failure mechanisms were evaluated. The difference between the moments based on yield line theory and experimental moments varied between 1% to 3%. Experimental and analysis results revealed that yield line analysis could conveniently be employed in the analysis of high strength reinforced concrete slabs.

Ultimate behavior of composite beams with shallow I-sections

Selçuk Emre Görkem,Metin Hüsem 국제구조공학회 2013 Steel and Composite Structures, An International J Vol.14 No.5

Bending behavior of reinforced concrete slabs encased over shallow I-sections at different levels of compression heads were investigated in present study. 1500 mm long I-sections were used to create composite slabs. Compression heads of monolithic experimental members were encased at different levels into the concrete slabs. Shear connections were welded over some of the I-sections. The testing was carried out in accordance with the principles of four-point loading. Results revealed decreasing load bearing and deflection capacities of composite beams with increasing encasement depths into concrete. Mechanical properties of concrete and reinforcing steel were also examined. Resultant stresses calculated for composite beams at failure were found to be less than the yield strength of steel beams. Test results were discussed with regard to shear and slip effect.

A treatise on irregular shaped concrete test specimens

Selçuk Emre Görkem 사단법인 한국계산역학회 2015 Computers and Concrete, An International Journal Vol.16 No.1

An experimental program has been carried out to investigate the effect of edge-slope on compressive strength of concrete specimens. In this study, effect of such slope was investigated by testing 100 standard cylinder specimens and 40 standard cubes. When molds are put on a slanted place, wet concrete starts to flow through the open end of mold. It keeps flowing until it reaches to a parallel surface with the place over which it was placed. That creates a sloped surface over the loading area. Experimental results revealed significant relationships between failure loads and slope of loading surface for cylinders. Angled cracks occurred in sloped cylinder specimens. Tension cracks occurred in cube specimens. Fracture mechanisms were also evaluated by using finite element analyses approach. Experiments yielded an exponential curve with bandwidth for cylinders. Average value of curve is between slope and compressive strength. Inclination is much effective parameter for cylinders than cubes.

Increased Bladder Wall Thickness in Diabetic and Nondiabetic Women With Overactive Bladder

Hakkı Uzun,Sabri Ogullar,Serap Baydur Şahin,Orhan Ünal Zorba,Görkem Akça,Fatih Sümer,Ülkü Mete Güney,Gülşah Balık 대한배뇨장애요실금학회 2013 International Neurourology Journal Vol.17 No.2

Purpose: Bladder wall thickness has been reported to be associated with overactive bladder (OAB) in women. Diabetic women have an increased risk for OAB syndrome and may have an increased risk for bladder wall thickness. Methods: A total of 235 female patients aged 40 to 75 years were categorized into four groups. The first group consisted of women free of urgency or urge urinary incontinence. The second group included nondiabetic women with idiopathic OAB. The third group consisted of women with diabetes and clinical OAB, and women with diabetes but without OAB constituted the fourth group. Bladder wall thickness at the anterior wall was measured by ultrasound by the suprapubic approach with bladder filling over 250 mL. Results: The diabetic (third group) and nondiabetic (second group) women with OAB had significantly greater bladder wall thickness at the anterior bladder wall than did the controls. However, the difference was not significant between the diabetic (third group) and the nondiabetic (second group) women with OAB. Women with diabetes but without OAB (fourth group) had greater bladder wall thickness than did the controls but this difference was not significant. Additionally, the difference in bladder wall thickness between diabetic women with (third group) and without (fourth group) OAB was not significant. Conclusions: This is the first study to show that bladder wall thickness is increased in diabetic women with and without OAB. Additionally, nondiabetic women with OAB had increased bladder wall thickness. Further studies may provide additional information for diabetic and nondiabetic women with OAB, in whom the etiopathogenesis of the disease may be similar.

The Relationship between Spontaneous Multi-Vessel Coronary Artery Dissection and Celiac Disease

Nermin Bayar,Göksel Cagırcı,Cagın Mustafa Üreyen,Görkem Kus,Selcuk Kücükseymen,Sakir Arslan 대한심장학회 2015 Korean Circulation Journal Vol.45 No.3

Celiac disease (CD) is an immune-mediated enteropathy involving the small intestines. Genetic and environmental risk factors as well as autoimmunity have been linked to its etiology. Studies have shown that coronary artery disease, autoimmune myocarditis, arrhythmias and premature atherosclerosis are more prevalent in individuals with CD compared to individuals without the disease. In this case report a young male patient with CD presented with acute myocardial infarction with spontaneous coronary artery dissections of two vessels. To the best of our knowledge, this is the first case report of spontaneous multi-vessel coronary artery dissection in a patient with CD.

Association Between Interleukin-6 and Head and Neck Squamous Cell Carcinoma: A Systematic Review

Uzdan Uz,Görkem Eskiizmir 대한이비인후과학회 2021 Clinical and Experimental Otorhinolaryngology Vol.14 No.1

Interleukin-6 (IL-6) is a proinflammatory cytokine which plays an important role in several regulatory mechanisms of cancer. Moreover, experimental and clinical studies have reported that IL-6 targeted therapies might provide significant benefits for cancer treatment. The purpose of this systematic review is to evaluate IL-6 activity in patients with head and neck squamous cell carcinoma (HNSCC). A systematic review of the association between serum, saliva and tumor IL-6 and HNSCC was developed on PubMed/Medline in the publication range from January 1995 to January 2019. Our literature analysis demonstrated that overexpression and elevated serum and/or saliva IL-6 concentrations in patients with HNSCC are related to poor survival and oncological outcomes. Although there is a correlation between IL-6 concentrations and tumorigenicity, it is noteworthy that IL-6 targeted therapies are generally performed in vitro and in experimental studies. Therefore, prospective, randomized clinical trials are required that focus on IL-6 targeted therapies for the treatment of HNSCC.

Mid-length Pedicle Screws in Posterior Instrumentation of Scoliosis

Tevfik Balikci,Görkem Kıyak,Ahmed Majid Heydar,Motasim Khalid Bawaneh,Murat Bezer 대한척추외과학회 2019 Asian Spine Journal Vol.13 No.5

Study Design: Prospective analysis of collected data. Purpose: We determine the need for the use of mid-length pedicle screws (screws with 2.5-mm long increments) during posterior spinal instrumentation. Overview of Literature: Many biomechanical studies have been performed showing that increasing the pedicle screw insertion depth provides an improved resistance to pullout, cyclic loading, and derotational forces, but no intermediate length screws were used. Methods: We prospectively evaluated 120 patients who received posterior segmental instrumentation for structural scoliosis. Preoperatively, 91.44-cm long cassette anteroposterior (AP), lateral, and AP bending radiographs and multiplanar computed tomography were performed in all patients routinely. We measured chord length to determine the maximum probable screw length of all vertebrae. All pedicle screws were attempted to be placed as long as possible. The main intention was at least to engage the subcortical bone of the anterior vertebral cortex. Especially in the apical region, the screws were attempted to be inserted bicortically. The length, level, region, and side of each screw were recorded. Screws with 5-mm increments were called standard length screws (SLS), and middle-sized screws with 2.5-mm increments were called mid-length screws (MLS). Results: Of 2,846 pedicle screws inserted, 1,575 (55.4%) were SLS and 1,271 (44.6%) were MLS, demonstrating a need for MLS in scoliosis surgery (p<0.05). The need for MLS increased significantly in the thoracic region, apical vertebrae, and convex side (p<0.05). Conclusions: If anterior cortex engagement or longer placement of pedicle screws is intended during scoliosis surgery, for safer placement, screws with 2.5-mm increments should be available in posterior instrumentation systems.