Leaching kinetics of ulexite in sodium hydrogen sulphate solutions

Erbil Kavcı,Turan C¸alban,Sabri C¸olak,Soner Kus¸ lu 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.5

The aim of this study was to investigate the dissolution kinetics of ulexite in sodium hydrogen sulphate solutions in a mechanical agitation system and to declare an alternative reactant to produce boric acid. Reaction temperature, concentration of sodium hydrogen sulphate solutions, stirring speed, solid/liquid ratio and ulexite particle size were selected as parameters of the dissolution rate of ulexite. The experimental results were successfully correlated by linear regression using Statistica program. Dissolution curves were evaluated in order to test shrinking core models for solid-fluid systems. It was observed that increase in the reaction temperature and decrease in the solid/liquid ratio cause an increase in the dissolution rate of ulexite. The dissolution extent is highly increased with increase in the stirring speed rate between 100 and 700 rpm experimental conditions. The activation energy was found to be 36.4 kJ/mol. The leaching of ulexite was controlled by diffusion through the ash or product layer. The rate expression associated with the dissolution rate of ulexite depending on the parameters chosen may be summarized as: 1–3(1 X)2/3 + 2(1 X) = 6.17 × C0.97 × W1.17 × D 1.72 × (S/L) 0.66 × e( 36.4/RT) t.

Ischemic Necrosis of the Cecum; A Single Center Experience

( Ebubekir Gundes ),( Tevfik Kucukkartallar ),( Muzaffer Haldun ?olak ),( Murat Cakir ),( Faruk Aksoy ) 대한소화기학회 2013 대한소화기학회지 Vol.61 No.5

Background/Aims: Isolated cecal necrosis is a rare cause of the surgical abdomen. Its manifestation is similar to that of acute appendicitis. Thirteen cases, who were pre-diagnosed with acute abdomen and were finally diagnosed with isolated cecal necrosis after operation have been evaluated alongside with literature. Methods: The records of 13 patients, who had isolated cecal necroses between 1995 and 2011 at Necmettin Erbakan University Meram Medical School`s General Surgery Clinic (Turkey), were retrospectively evaluated. Results: Eight of the patients were male, whereas 5 were female. Their mean age was 68.0±11.7 (range 51-84) years. All the patients had at least one accompanying disease the most frequent of which were heart failure and chronic renal failure. Ten patients had right hemicolectomy and ileotransversostomy, two had right hemicolectomy and ileostomy, and one had wedge resection to the cecum by the help of linear stapler. Mortality was seen in 5 patients (38%) in the early postoperative period. Conclusions: Isolated cecal necrosis should be considered in elderly patients with chronic diseases presenting with sudden right lower quadrant pains in the differential diagnosis. Isolated cecal necrosis may have a bad prognosis since it is seen in elderly patients with accompanying problems. Therefore, early diagnosis and immediate surgical management if necessary is important to reduce the risk of morbidity and mortality.

Temperamental Characteristics in Adults with Attention-Deficit Hyperactivity Disorder: A Comparison with Bipolar Disorder and Healthy Control Groups

Suat Ekinci,Kadir Ozdel,Bedriye Oncu,Burç,in Ç,olak,Hasan Kandemir,Saynur Canat 대한신경정신의학회 2013 PSYCHIATRY INVESTIGATION Vol.10 No.2

Objective-To date, the affective temperamental characteristics of adults with attention-deficit hyperactivity disorder (ADHD) have not been studied. The aim of this study is to explore those temperamental characteristics for adults diagnosed with ADHD as measured by the TEMPS-A and then to compare those results with results for individuals diagnosed with bipolar disorder (BD) and with healthy controls. Methods-Forty adults with ADHD, 40 patients with BD, and 40 healthy controls were enrolled in this study. The groups were matched by age and gender. All patients were assessed using the Structured Clinical Interview for DSM-IV Axis I Disorders (SCID I), the Hamilton Depression Rating Scale, the Hamilton Anxiety Rating Scale, the Young Mania Rating Scale and the Wender Utah Rating Scale. Subjects’ temperamental characteristics were examined using the Turkish version of the Temperament Evaluation of Memphis, Pisa, Paris and San Diego-auto questionnaire (TEMPS-A). Results-Ten subjects (25%) in the ADHD group and 15 subjects (30%) in the bipolar group had at least one dominant temperament. There was no identifiable dominant temperament in the control group. Compared to the control group, the ADHD group scored higher than other groups on all domains of the TEMPS-A: depressive cyclothymic, irritable and anxious. However, the hyperthymic domain was not higher for this group. Adults with ADHD scored higher on the irritable temperament scale as compared to the BD group. The ADHD and BD groups had similar mean scores for each of the other four temperaments. Conclusion-The adults diagnosed with ADHD in this study had different temperamental characteristics from the control group, and these temperamental characteristics were similar to those of the bipolar patients. Recognizing the role of temperamental characteristics in adults with ADHD may increase our understanding of ADHD.

Synthesis and characterization of Fe-Doped CdO binary system

Hakan ÇOLAK,Orhan TÜRKO LU 한양대학교 세라믹연구소 2013 Journal of Ceramic Processing Research Vol.14 No.5

This paper reports the synthesis, crystal structure and electrical conductivity properties of Fe-doped CdO powders. Monophase samples, which were indexed as cubic structure in the Fe-CdO system, were determined by X-ray diffraction. The limit solubility of Fe ions in the CdO lattice is 2 mol % after heating at 850 o C. The impurity phase was determined as cubic-CdFe2O4. The research focused on the single I- phase, which were synthesized at 850 o C because of the limit of the solubility range is widest at this temperature. It was observed that the lattice parameters a of the I-phase decreased with Fe doping concentration. The electrical conductivity values of pure CdO (after heating at 850 o C), 0.25 and 2 mol % Fe-doped CdO samples (after heating at 850 o C) at 100 o C were 79, 525 and 1349Ω−1 • cm−1 , and at 850 o C they were 891, 1413 and 3548 Ω−1 • cm−1 , respectively. In other words, electrical conductivity increased with Fe doping.

Barbed sutures versus conventional tenorrhaphy in flexor tendon repair: An ex vivo biomechanical analysis

Özlem Çolak Aslan,Yüksel Kankaya,Nezih Sungur,Kadri Özer,Koray Gürsoy,Kemal Şerbetçi,Uğur Koçer 대한성형외과학회 2019 Archives of Plastic Surgery Vol.46 No.3

Background The management of flexor tendon injuries has evolved in recent years through industrial improvements in suture materials, refinements of repair methods, and early rehabilitation protocols. However, there is no consensus on the ideal suture material and technique. This study was conducted to compare the tensile strength, repair time, and characteristics of 4-strand cruciate, modified Kessler, and 4-strand horizontal intrafiber barbed sutures for flexor tenorrhaphy with a 12-mm suture purchase length in an animal model. Methods The right third deep flexors of 60 adult Leghorn chicken feet were isolated and repaired with a 12-mm suture purchase length. The tendons were randomly assigned to three groups of equal number (n=20 each). Groups 1 and 2 received 4-strand cruciate and modified Kessler repair with conventional suture materials, respectively. A 4-strand horizontal intrafiber barbed suture technique was used in group 3. The repaired tendons were biomechanically tested for tensile strength, 2-mm gap resistance, and mode of failure. Repair times were also recorded. Results The maximum tensile strength until failure was 44.6±4.3 N in group 1, 35.7±5.2 N in group 2, and 56.7±17.3 N in group 3. The barbed sutures were superior to the other sutures in terms of the load needed for 2-mm gap formation (P<0.05). Furthermore, the barbed sutures showed the shortest repair time (P<0.05). Conclusions This study found that 4-strand horizontal intrafiber barbed suture repair with a 12-mm purchase length in a chicken flexor tendon injury model showed promising biomechanical properties and took less time to perform than other options.

Dynamic ultrasound examination of the median nerve during follow-up after wrist fracture/surgery

( Ahmet Furkan Çolak ),( Ayşe İrem Yeşiloğlu ),( Alpaslan Fatih Kaynar ),( Bayram Kaymak ),( Levent Özçakar ) 영남대학교 의과대학 2024 Yeungnam University Journal of Medicine Vol.41 No.1

Characteristics, issues, and future directions in Chinese multicultural education: a review of selected research 2000–2018

Liu Qian,Çolak Fatma Zehra,Agirdag Orhan 서울대학교 교육연구소 2020 Asia Pacific Education Review Vol.21 No.2

Multicultural education has aroused extensive international attention and has been promoted by a large body of advocates due to its signifcance for the achievement of social equity in education. Such worldwide concern, therefore, calls for collaborative work, with contributions from diverse sociocultural contexts. This paper reviews 179 research studies on Chinese multicultural education (CME) from 2000 to 2018. Six interrelated categories were identifed: (1) theoretical discourses on CME; (2) multicultural curricula and instruction; (3) students’ perspectives in multicultural contexts; (4) multilingual education and language policy; (5) citizenship education; and (6) multicultural teaching and teacher education. Each category was thoroughly examined and the limitations were discussed. Also, the paper identifed various issues that future research needs to address, such as broadening the concept of multicultural education, the academic communication between China and the West, and the need for empirical literature in English.

Fractured needle as an unusual complication of the lingual nerve block: a case report

Aras Erdil,Mustafa Sami Demirsoy,Sefa Çolak 대한치과마취과학회 2022 Journal of Dental Anesthesia and Pain Medicine Vol.22 No.4

Although rare, hypodermic needle fractures can occur in the maxillofacial region. In cases of fracture, urgent intervention is required to prevent further complications. We present the case of a 37-year-old female patient with a fractured needle in the left sublingual fossa during a lingual nerve block 6 months before referral. The fragment of a 30-gauge needle was located using cone-beam computed tomography and retrieved under local anesthesia with blunt dissection. The patient recovered uneventfully, except for predictable postoperative inflammatory complications, which resolved within 2 weeks. Precautions should be implemented to prevent needle fractures, which are usually preventable. However, if the retrieval is unsuccessful, the patient should be referred to a well-equipped surgical unit without delay.

Electromyographic and Clinical Investigation of the Effect of Platelet-Rich Plasma on Peripheral Nerve Regeneration in Patients with Diabetes after Surgery for Carpal Tunnel Syndrome

Yasak Tuğçe,Özkaya Özay,Ergan Şahin Ayça,Çolak Özlem 대한성형외과학회 2022 Archives of Plastic Surgery Vol.49 No.1

Background Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy. Studies have shown that results of CTS surgery are poorer in patients with diabetes. In this study, the effect of platelet-rich plasma (PRP) on nerve regeneration was investigated through clinical and electromyographic findings in patients with diabetes who underwent CTS surgery.Methods A retrospective analysis of 20 patients with diabetes who had surgically decompressed CTS was conducted. Patients were divided into two groups. The study group received PRP treatment following surgery. The control group did not receive any treatment. Patients were assessed using electromyography and the Boston Carpal Tunnel Syndrome Questionnaire preoperatively as well as postoperatively at 3-month, 6-month, and 1-year follow-ups visits.Results There was a decrease in complaints and an improvement in sensory and motor examinations in both groups. The Boston Carpal Tunnel Syndrome Questionnaire scores did not show any statistically significant differences between the two groups. However, electromyographic findings showed that there were statistical differences between preoperative and postoperative (3 months, 6 months, and 1 year) results in both groups. When the two groups were compared using preoperative and postoperative (3 months, 6 months, and 1 year) electromyographic values, no statistically significant differences were seen.Conclusion Single injections of PRP did not have a significant impact on median nerve regeneration following CTS surgery in patients with diabetes. The effectiveness of multiple PRP injections can be investigated in patients with diabetes in future studies.

Compression after Impact and Charpy Impact Characterizations of Glass Fiber/Epoxy/MWCNT Composites

Özgür Demircan,Kemal Kadıoğlu,Pınar Çolak,Erdinç Günaydın,Mustafa Doğu,Neslihan Topalömer,Volkan Eskizeybek 한국섬유공학회 2020 Fibers and polymers Vol.21 No.8

In this study, glass fiber/epoxy resin/multi-walled carbon nanotubes (MWCNTs) were used to fabricate hybridcomposites with biaxial warp-knitted fabrics. The biaxial warp-knitted fabrics were grafted with various amounts ofMWCNTs and the hybrid composites were fabricated using the resin transfer molding (RTM) method, subsequently. Thefabricated samples were subjected to compression after impact and Charpy impact tests. The hybrid composites exhibitedhigher compression after impact modulus and strength with 26 % and 17 % compared to the samples without nanotubes,respectively. Moreover, the MWCNTs integrated specimens showed 17 % improvement of Charpy impact strength againstspecimens without carbon nanotubes in 0odegree direction. Fracture surface analysis revealed lower number of cracks andshorter crack propagation lengths in the MWCNTs reinforced specimens. The improvement in mechanical properties of thehybrid composites can most likely be attributed to an increase in interfacial adhesion due to the presence of the carbonnanotubes.