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    Evaluation of early thyroidectomy complications
    (Bayrakol Medical Publisher, 2022) Karatas, Turgay; Selcuk, Engin Burak; Karatas, Mehmet; Yildirim, Atilla; Ozbag, Davut; Cay, Mahmut; Senol, Deniz
    Aim: Our aim in this study is to reveal the relationships between patient findings, surgical methods and early thyroidectomy complications. Material and Methods: The files and operative notes of 308 patients who underwent thyroidectomy within 10 years were reviewed retrospectively. Gender, age, preoperative diagnosis, primary or reoperated cases, the type of thyroidectomy [ bilateral subtotal (BST), bilateral total (BTT), unilateral subtotal (UST) and unilateral total (UTT)] and early postoperative complications (hypocalcemia, bleeding, nervus laryngeus recurrens (NLR) injury, infection and seroma) were recorded. The peculiarity of this study is that NLR neuromonitoring was not used in thyroidectomy operations. Results: Of the 308 patients who underwent thyroidectomy, 287 were females and 21 were males. Two hundred eighty three cases of multinodular goiter, 18 cases of nodular goiter and 7 thyroid cancers were operated; 180 BTT, 100 BST, 17 UTT + UST, 7 UST and 4 UTT were applied. Complications were seen in a total of 20 (6.49%) patients who underwent 19 BTT and 1 BST. The only complication in BST was bleeding. There were 10 (3.24%) hypocalcemia, 4 (1.29%) bleeding, 2 (0.649%) NLR injury, 2 (0.649%) infections and 2 (0.649%) seromas. In terms of the frequency of early thyroidectomy complications, hypocalcemia was the first (P=0.0047). In addition, the rates of hypocalcemia and NLR injury were higher in reoperated patients than in primary patients (P<0.05). Discussion: The most common complication was hypocalcemia. NLR injury and hypocalcemia rates were higher in reoperated cases who underwent BTT.
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    Experimental determination of electrical and thermo-physical characteristics of dielectric nanofluids based on volume fraction change
    (Elsevier Science Sa, 2023) Karatas, Mehmet; Bicen, Yunus
    Dielectric insulating fluids perform critical tasks such as electrical insulation and cooling functions in power system equipment. Improving the thermal properties of insulating fluids extends the service life of power equipment, while improving their dielectric properties ensures a reliable and safe electricity supply. Therefore, studies on enhancing the thermal and dielectric qualities of dielectric fluids using nanoparticles have become more popular in recent years. In this study, the dielectric and thermo-physical properties of mineral oil-based SiO2 nanoparticle suspensions, namely nanofluids, have been investigated. An approximately 25.6% enhance-ment in AC breakdown voltage level has been obtained at a 0.05% critical volume fraction. It has been noted that the level of the AC breakdown voltage decreases when the critical volume fraction is exceeded. The thermal conductivity of the prepared nanofluid has changed logarithmically in the positive direction according to the rising number of nanoparticles per unit volume. Thermal conductivity has increased by around 8.55% for the critical volume fraction value, whereas thermal diffusivity has increased by approximately 22%. Similarly, when the number of particles in the nanofluid rises, the viscosity increases nonlinearly. The viscosity increase, which is undesirable for heat transfer, has been determined to be around 10.64% for the crucial volume fraction. These findings indicate that dielectric nanofluids hold significant potential for the future. The SEM analysis, on the other hand, explains the difficulties of assuring the long-term stability of nanofluids in the volume fraction with the highest AC dielectric breakdown voltage.