The Reconstruction of Nasal Septal Perforation with High Density Porous Polyethylene Covered with Fascia Lata: An Experimental Study on Rabbit Model

Güven Yildirim,Vedat Onar,Ibrahim Sayin,Suzan Deniz Onol,Tamer Aydin 대한이비인후과학회 2011 Clinical and Experimental Otorhinolaryngology Vol.4 No.3

Objectives. Evaluation of a new material, high-density porous polyethylene (HDPP), which is covered with fascia lata, for experimental nasal septal perforation closure. Methods. Twenty New Zealand albino rabbits were included and divided into study and control groups. A lateral incision was made from the lateral aspect of the left nares to the incisura nasomaxillaris. After exposure of the cavum nasi,the nasal mucoperichondrium was elevated bilaterally. A full-thickness 0.5×0.5-cm perforation was created over the septum nasi with a No. 11 surgical blade. A fascia lata graft was used for the study group. The HDPP was covered with fascia lata and placed under the elevated mucosa. HDPP without a fascial covering was used in the control group. Four months after the procedure, magnetic resonance imaging was performed to evaluate resorption of the material. The animals were sacrificed, and the nasal septum was completely removed. Macroscopic and histopathological examinations were performed on the nasal septum. Results. All rabbits had survived after the 4-month period. Macroscopically, nine of 10 (90%) perforations were closed in the fascia lata-covered HDPP group. Histopathological examination of these nine rabbits revealed that the continuity of cartilage was disturbed in the perforation areas. Granulation tissue was inverted in areas in which the cartilage continuity was disturbed. The HDPP had remained intact at the edge of the perforation. In the HDPP group, six of 10 implants were still perforated (60%) and four (40%) were closed. The fascia lata-covered HDPP implant had a significantly higher perforation closure rate than that of the HDPP implant alone (P<0.05). Conclusion. In cases of septal perforation, it is better to cover the HDPP implant with fascia lata. This covered implant can be used for the repair of nasal septal perforations. HDPP implants are easy to work with and avoid the increased operative time and morbidity associated with harvesting autografts.

Effect of SiC Nanofiber Addition on Microstructure, Mechanical Properties and Creep Behaviour of High Pressure Die Cast AZ91-1Sr Alloy

Güven Yarkadaş,Hüseyin Şevik 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.6

Effects of nanofiber SiC (0.5 and 1 vol%) addition on microstructure, mechanical properties and creep behaviour of coldchamber high pressure die casting AZ91-1Sr alloy have been investigated. Experimental results indicate that the AZ91-1Sralloy contains of α-Mg, β-Mg17Al12 and Al4Srintermetallic phases. With addition of nanofiber SiC, the Al4C3and SiCpeaks were detected. Also, the mechanical properties of the matrix alloy were improved. The AZ91-1Sr-1%SiC nanocompositedisplays the best yield strength and hardness increment. Furthermore, the creep resistance of the matrix alloy wasincreased with increasing nanofiber SiC and the best creep resistance was obtained in the AZ91-1Sr-1SiC nanocomposite. The values of stress exponents and the activation energies for experimental specimen were found between 3.17–5.54 and103.5–155.3 kJ/mol., respectively. When considered the results obtained from the values of stress exponents, the activationenergies and SEM micrographs, it was thought that the dominant creep mechanism for the matrix alloy and nanocompositesis dislocation climb controlled.

The use of platelet rich plasma in the treatment of immature tooth with periapical lesion: a case report

Günseli Güven Polat,Ceren Yıldırım,Özlem Martı Akgün,Ceyhan Altun,Didem Dinçer,Cansel Köse Özkan 대한치과보존학회 2014 Restorative Dentistry & Endodontics Vol.39 No.3

This study describes the treatment of an immature permanent tooth with periapical lesion which was treated with regenerative approach using platelet rich plasma (PRP). The root canal of immature human permanent tooth with periapical lesion was gently debrided of necrotic tissue and disinfected with 2.5% NaOCl, and then medicated with triple antibiotic paste comprised of ciprofloxacin, metronidazole, and tetracycline. When the tooth was asymptomatic, PRP and mineral trioxide aggregate (MTA) were placed into the root canal. Six months after PRP treatment, radiographical examination revealed resolution of the radiolucency and progressive thickening of the root wall and apical closure. Our findings suggest that PRP can be used for the treatment of immature permanent teeth with periapical lesion, as part of a regenerative endodontic treatment procedure.

C-reactive protein-albumin ratio and procalcitonin in predicting intensive care unit mortality in traumatic brain injury

Canan Gürsoy,Güven Gürsoy,Semra Gümüş Demirbilek 대한중환자의학회 2022 Acute and Critical Care Vol.37 No.3

Background Prediction of intensive care unit (ICU) mortality in traumatic brain injury (TBI), which is a common cause of death in children and young adults, is important for injury management. Neuroinflammation is responsible for both primary and secondary brain injury, and C-reactive protein-albumin ratio (CAR) has allowed use of biomarkers such as procalcitonin (PCT) in predicting mortality. Here, we compared the performance of CAR and PCT in predicting ICU mortality in TBI. Methods Adults with TBI were enrolled in our study. The medical records of 82 isolated TBI patients were reviewed retrospectively. Results The mean patient age was 49.0 ± 22.69 years; 59 of all patients (72%) were discharged, and 23 (28%) died. There was a statistically significant difference between PCT and CAR values according to mortality (P<0.05). The area under the curve (AUC) was 0.646 with 0.071 standard error for PCT and 0.642 with 0.066 standard error for CAR. The PCT showed a similar AUC of the receiver operating characteristic to CAR. Conclusions This study shows that CAR and PCT are usable biomarkers to predict ICU mortality in TBI. When the determined cut-off values are used to predict the course of the disease, the CAR and PCT biomarkers will provide more effective information for treatment planning and for preparation of the family for the treatment process and to manage their outcome expectations.

A Study on Optimum Machinability of NiTi Shape Memory Alloy Via AWJ

Sedat Güven,Meltem Altın Karataş,Hasan Gökkaya 한국정밀공학회 2024 International Journal of Precision Engineering and Vol.25 No.3

The high ductility behaviour and high hardening of Nickel–Titanium (NiTi) alloys during cutting make them one of the alloys with low machinability. In addition, poor chip breakage and high tool wear are observed when machining these materials with conventional manufacturing methods. One of the unconventional processing methods, abrasive water jet (AWJ), is an alternative method for cutting low machinability materials. In this study, NiTi shape memory alloy (SMA) was subjected to AWJ drilling under different machining parameters. The aim of the research is to determine the optimum kerf (K), surface roughness (Ra) and material removal rate (MRR) variables resulting from the drilling process by examining the effect of process variables such as water pressure (WP), stand-off distance (SoD) and feed rate used in AWJ machining of NiTi SMAs. Taguchi-based Gray Relational Analysis (GRA), one of the multi-criteria decision-making methods, was used to optimise machining parameters in the drilling of NiTi SMAs with AWJ. The effect percentages of the test levels in the drilling operations were determined using Analysis of Variance (ANOVA). As a result of the experimental study, optimum levels were obtained for K, MRR and Ra at low WP, medium SoD and high feed rate. According to the result obtained from ANOVA, the parameter with the highest effect on K, MRR and Ra was determined as feed rate with 34.65%.

Thiol/Disulfide Homeostasis in Bipolar and Unipolar Depression

Gamze Erzin,Güven Özkaya,Canan Topçuoğlu,Rabia Nazik Yüksel,Özcan Erel,Emine Feyza Yurt,Erol Göka,Sinan Gülöksüz 대한정신약물학회 2020 CLINICAL PSYCHOPHARMACOLOGY AND NEUROSCIENCE Vol.18 No.3

Objective: Bipolar disorder and unipolar depressive disorder are complex phenotypes. There appear to be phenotypical, mechanistic, and therapeutic differences between bipolar depression (BD) and unipolar depression (UD). There is a need for understanding the underlying biological variation between these clinical entities. The role of oxidative processes underlying bipolar disorder and depression has been demonstrated. Thiol-disulfide homeostasis (TDH) is a recent oxidative stress marker. In this study, we aimed to inspect patients with bipolar depression and unipolar depression in terms of thiol-disulfide balance and to compare them with healthy controls. Methods: Patients admitted to the outpatient clinic of Ankara Numune Training and Research Hospital and diagnosed either as a depressive episode with bipolar disorder (n = 37) or unipolar depression (n = 24) according to DSM-5 criteria, along with healthy controls (HC) (n = 50), were included in the study. Native thiol, total thiol, and disulfide levels were compared across the groups. Results: In comparison to HC, both BD and UD groups had higher disulfide levels, disulfide/native thiol ratio, and disulfide/total thiol ratio. No significant differences between BD and UD were detected in terms of disulfide level, disulfide/ native thiol ratio, and disulfide/total thiol ratio. Conclusion: Increased levels of disulfide, native thiol, and disulfide/total thiol ratios compared to healthy controls in both UD and BD groups may be indicative of the presence of oxidative damage in these two clinical conditions. To clarify the role of oxidative stress in the pathophysiology of depressive disorders and investigate TDH, longitudinal studies in patients with medication-free UD and BD are required.

An Analysis of Myocardial Efficiency in Patients with Severe Asymptomatic Mitral Regurgitation

Rengin Çetin Güvenç,Emre Aruğaslan,Tolga Sinan Güvenç,Fatma Özpamuk Karadeniz,Hülya Kaşıkçıoğlu,Neşe Çam 한국심초음파학회 2020 Journal of Cardiovascular Imaging (J Cardiovasc Im Vol.28 No.4

BACKGROUND: It is difficult to determine left ventricular systolic performance in patients with severe mitral regurgitation (MR) since left ventricular ejection fraction (EF) could be preserved until the end stages of the disease. Myocardial efficiency (MEf) describes the amount of external work (EW) done by the left ventricle per unit of oxygen consumed (mVO2). In the present study, we aimed to investigate MEf in patients with asymptomatic severe MR using a novel echocardiographic method. METHODS: A total of 27 patients with severe asymptomatic MR and 26 healthy volunteers were included in this cross-sectional study. EW was measured using stroke volume and blood pressure, while mVO2 was estimated using double product and left ventricular mass. RESULTS: There were no differences between the groups with regards to EF (66% ± 5% vs. 69% ± 7%), while MEf was significantly reduced in patients with severe MR (25% ± 11% vs. 44% ± 12%, p < 0.001). This difference was maintained even after adjustment for age, gender and body surface area (adjusted ̅ : 0.44, 95% CI: 0.39–0.49 for controls and adjusted ̅ : 0.24, 95% CI: 0.19–0.29 for patients with severe MR). Further analysis showed that this reduction was due to an increase in total mVO2 in the severe MR group. MEf of thepatients who were both on β-blockers and angiotensin converting enzyme inhibitors/angiotensin receptor blockers were higher than those who were not on any drugs, but this difference was not statistically significant (32% ± 15% vs. 23% ± 9%, p = 0.41). CONCLUSIONS: MEf was significantly lower in patients with asymptomatic severe MR and preserved EF.

The metameric effect of monolithic zirconias with varying yttrium ratios

Mehmet Ejder Güven,Özlem Kara 대한치과보철학회 2024 The Journal of Advanced Prosthodontics Vol.16 No.1

Purpose. This study aims to evaluate the accuracy of different shade selection techniques and determine the matching success of crown restorations fabricated using digital shade selection techniques. Materials and methods. Teeth numbers 11 and 21 were prepared on a typodont model. For the #11 tooth, six different crowns were fabricated with randomly selected colors and set as the target crowns. The following four test groups were established: Group C, where the visual shade selection was performed using the Vita 3D Master Shade Guide and the group served as the control; Group Ph, where the shade selection was performed under the guidance of dental photography; Group S, where the shade selection was performed by measuring the target tooth color using a spectrophotometer; and Group I, where the shade selection was performed by scanning the test specimens and target crowns using an intraoral scanner. Based on the test groups, 24 crowns were fabricated using different shade selection techniques. The ΔE values were calculated according to the CIEDE2000 (2:1:1) formula. The collected data were analyzed by means of a one-way analysis of variance. Results. For the four test groups (Groups C, Ph, S, and I), the following mean ΔE values were obtained: 2.74, 3.62, 2.13, and 3.5, respectively. No significant differences were found among the test groups. Conclusion. Although there was no statistically significant difference among the shade selection techniques, Group S had relatively lower ΔE values. Moreover, according to the test results, the spectrophotometer shade selection technique may provide more successful clinical results.

Erratum-Comparison of retention forces with various fabrication methods and materials in double crowns

Melahat Çelik Güven,Meral Tuna,Ergun Bozdağ,Gizem Nur Öztürk,Gulsen Bayraktar 대한치과보철학회 2017 The Journal of Advanced Prosthodontics Vol.9 No.6

The article ‘Comparison of retention forces with various fabrication methods and materials in double crowns’ authored by Melahat Çelik Güven, Meral Tuna, Ergun Bozdağ, Gizem Nur Öztürk, and Gulsen Bayraktar, published in August issue [Vol 9, No 4] of The Journal of Advanced Prosthodontics (2017), has an erratum. In the above article, the financial grant has been erroneously omitted, so it would be disclosed as below. Funding: This study was supported by the Research Fund of Istanbul University. Project No. 50058. The Journal of Advanced Prosthodontics apologizes to the readers for this error.

DESIGN AND EVALUATION OF ROBUST COOPERATIVE ADAPTIVE CRUISE CONTROL SYSTEMS IN PARAMETER SPACE

Mümin Tolga Emirler,Levent Güvenç,Bilin Aksun Güvenç 한국자동차공학회 2018 International journal of automotive technology Vol.19 No.2

This paper is on the design of cooperative adaptive cruise control systems for automated driving of platoons of vehicles in the longitudinal direction. Longitudinal models of vehicles with simple dynamics, an uncertain first order time constant and vehicle to vehicle communication with a communication delay are used in the vehicle modeling. A robust parameter space approach is developed and applied to the design of the cooperative adaptive cruise control system. D-stability is chosen as the robust performance goal and the feedback PD controller is designed in controller parameter space to achieve this D-stability goal for a range of possible longitudinal dynamics time constants and different values of time gap. Preceding vehicle acceleration is sent to the ego vehicle using vehicle to vehicle communication and a feedforward controller is used in this inter-vehicle loop to improve performance. Simulation results of an eight vehicle platoon of heterogeneous vehicles are presented and evaluated to demonstrate the efficiency of the proposed design method. Also, the proposed method is compared with a benchmark controller and the feedback only controller. Time gap regulation and string stability are used to assess performance and the effect of the vehicle to vehicle communication frequency on control system performance is also investigated.