Van Yüzüncü Yıl Üniversitesi

Permanent URI for this communityhttps://hdl.handle.net/20.500.14720/1

Browse

Now showing 1 - 20 of 2064

12 Years After Roboski: Prolonged Grief and Posttraumatic Effects
(American Psychological Association, 2025) Ayhan, C.H.; Tanhan, F.; Yağan, F.; Avcı Erdal, N.; Öztürk, G.; Bedir, G.; Aslangiri, S.
Objective: The Roboski massacre, which took place on December 28, 2011, is remembered as a major tragedy resulting from a cross-border operation by the Turkish Air Force that led to the loss of 34 civilians, including 19 children. This event not only caused significant physical losses but also left a profound psychological, social, and political impact on those affected. An enhanced comprehension of prolonged grief disorder’s development can assist professionals in identifying bereaved individuals requiring assistance and augment the efficacy of treatments. The aim of this study is to examine the relationship between the grief process and symptoms of posttraumatic stress, perceived discrimination, and political trust within the framework of the theory of prolonged grief in a sample of the bereaved family members who lost their relatives in the Roboski massacre almost 12 years postloss. Method: In total, 88 Kurdish individuals (Mage = 37.13, SD = 16.4; 53.4% males) who had lost their close relatives in the Roboski incident in 2011 participated in this study. The Prolonged Grief Scale, the Posttraumatic Stress Disorder Checklist for Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, the Perceived Discrimination Scale, and the Political Trust Scale were used to collect data. Results: The findings of the study revealed that, even approximately 12 years after the Roboski massacre, a significant portion of the participants continue to experience symptoms of prolonged grief and posttraumatic stress reactions. There was a positive correlation between prolonged grief symptoms and posttraumatic stress reactions (r =.71) as well as perceived discrimination (r =.53). It was also found that the subdimensions of posttraumatic stress, namely “reexperiencing” (β =.19, p <.05), “negative cognitive alterations” (β =.39, p <.05), and “perceived collective discrimination” (β =.11, p <.05), were significant predictors of prolonged grief. Conclusions: Our findings revealed that professionals should focus on identifying bereaved people who experience prolonged grief after a traumatic loss. Targeting these symptoms may alleviate the exacerbation of persistent grief reactions several years after a traumatic loss.Our findings suggest that addressing prolonged grief disorder following a massacre requires a multifaceted approach that includes early intervention, tailored therapeutic strategies, and robust social support systems. By integrating these elements, mental health professionals can significantly improve outcomes for those affected by traumatic loss, facilitating a path toward recovery and resilience. © 2025 American Psychological Association
The 23 October 2011 Mw7.0 Van (Eastern Turkey) Earthquake: Interpretations of Recorded Strong Ground Motions and Post-Earthquake Conditions of Nearby Structures
(Earthquake Engineering Research Institute, 2014) Akansel, V.; Ameri, G.; Askan, A.; Caner, A.; Erdil, B.; Kale, O.; Okuyucu, D.
A major thrust-fault earthquake of MW = 7.0 occurred on 23 October 2011 at 10:41:21 UTC in the eastern Anatolian region of Turkey, severely affecting the nearby towns of Van and Erciş. In this study, a few strong-motion records from the epicentral area are analyzed in order to investigate the characteristics of the ground motions. Also reported are the post-earthquake field observations for various types of structures, such as buildings, bridges, historical structures, tunnels, and dams within the vicinity of the fault plane. The spatial distribution of damage indicates a noticeable hanging-wall effect. The special-type structures are observed to experience far less damage, as opposed to the building structures in the region pointing to the need for strict compliance to seismic building code and the corresponding construction requirements.© 2014, Earthquake Engineering Research Institute.
A 3-Day Boy With a Right Preauricular Swelling
(Springer, 2010) Akgun, Cihangir; Peker, Erdal; Akbayram, Sinan; Dogan, Murat; Tuncer, Oguz; Kirimi, Ercan
A 3-day-old boy was admitted for right preauricular swelling. Examination showed a toxic looking neonate with poor neonatal reflexes. There was erythema and swelling of 4 x 3 cm at the level of the right cheek. Laboratory investigation pointed to a bacterial infection. With parenteral antibiotics, the lesion resolved completely.
5-fluoro/(trifluoromethoxy)-2-indolinone Derivatives With Anti-Interleukin Activity
(Wiley-v C H verlag Gmbh, 2023) Soylu-Eter, Ozge; Sevincli, Zekiye Seyma; Ersoy, Betul; Hasanusta, Bahar; Gatfar, Ugur; Lack, Nathan A.; Karali, Nilgun
The pro-inflammatory cytokine interleukin-1 (IL-1) drives the pathogenesis of several inflammatory diseases. Recent studies have revealed that 2-indolinones can modulate cytokine responses. Therefore, we screened several 2-indolinone derivatives in preliminary studies to develop agents with anti-IL-1 activity. First, the putative efficacies and binding interactions of 2-indolinones were evaluated by docking studies. Second, previously synthesized 5-fluoro/(trifluoromethoxy)-1H-indole-2,3-dione 3-(4-phenylthiosemicarbazones) (compounds 47-69) which had the highest inhibitory effect in the screening were evaluated for inhibitory effects on the IL-1 receptor (IL-1R). Compounds 52 (IC50 = 0.09 mu M) and 65 (IC50 = 0.07 mu M) were selected as lead compounds for the subsequent synthesis of new derivatives. The novel 5-fluoro/(trifluoromethoxy)-1H-indole-2,3-dione 3-(4-phenylthiosemicarbazones) (compounds 70-116) were designed, synthesized, and in vitro studies were completed. The compounds 76, 78, 81, 91, 100, 105, and 107 tested showed nontoxic inhibitory effects on IL-1R-dependent responses in the range of 0.01-0.06 mu M and stronger than the lead compounds 52 and 65. In vitro and in silico findings showed that compounds 78 (IC50 = 0.01 mu M) and 81 (IC50 = 0.02 mu M) had the strongest IL-1R inhibitory effects and the most favorable drug-like properties. Molecular modeling studies of the compounds 78 and 81 were carried out to determine the possible binding interactions at the active site of the IL-1R. Novel 5-fluoro/(trifluoromethoxy)-2-indolinone derivatives were designed and synthesized based on in silico and preliminary in vitro test results from lead compounds. All compounds tested displayed nontoxic IL-1 receptor inhibitory effects at IC50 values in the range of 10 nM to 13 mu M, and seven compounds showed inhibitory responses stronger than the lead compounds at 0.01-0.06 mu M.image
Abcisic Acid and Gibberellic Acid Cause Increased Lipid Peroxidation and Fluctuated Antioxidant Defense Systems of Various Tissues in Rats
(Elsevier Science Bv, 2007) Celik, Ismail; Turker, Musa; Tuluce, Yasin
The study was aimed at demonstrating changes in the antioxidant defense systems [Reduced glutathione (GSH), glutathione reductase (GR), superoxide dismutase (SOD), glutathione-S-transferase (GST) and catalase (CAT)] forming an antioxidative barrier and oxidative stress parameter (Malondialdehyde = MDA) in the various tissues of Sprague-Dawley rats which were administrated plant growth regulators (PGRs) [Abcisic acid (ABA) and Gibberellic acid (GA(3))] during 25 days. Seventy five parts per million of ABA and GA(3) as drinking water were administered orally to rats (Sprague-Dawley albino) ad libitum for 25 days continuously. The PGRs treatments caused different effects on antioxidant defense systems and MDA content of experimented rats compared to controls. The lipid peroxidation end product MDA significantly increased in the spleen and lungs of rats treated with ABA and GA(3) without significantly change in the other tissues. The GSH levels were significantly increased in the lungs and stomach of rats treated with ABA without any change in the tissues of rats treated with GA(3). Antioxidant enzyme activities such as SOD significantly increased in the spleen of rats treated with ABA and GA(3). Meanwhile, SOD significantly increased in the kidney of rats treated with GA. CAT significantly decreased in the lungs treated with ABA but did not change significantly in all the rest of rat tissues treated with both the PGRs. On the other hand, the ancillary enzyme GR activity decreased in the spleen and increased in the kidney with GA(3) treatment. The drug metabolizing enzyme GST activity significantly decreased in the heart of rats treated with GA(3) but increased in the spleen and lungs of rats treated with both PGRs. The observations presented led us to conclude that administration of subacute ABA and GA(3) promotes lipid peroxidatin content and alters in the antioxidative systems in the rat's various tissues. These data, along with changes, suggest that the PGRs produced oxidative stress in rats during the period of a 25-day subchronic exposure. (C) 2007 Elsevier B.V. All rights reserved.
Abnormal Left Ventricular Longitudinal Functional Reserve Assessed by Exercise Pulsed Wave Tissue Doppler Imaging in Patients With Subclinical Hypothyroidism
(Endocrine Soc, 2009) Akcakoyun, Mustafa; Kaya, Hasan; Kargin, Ramazan; Pala, Selcuk; Emiroglu, Yunus; Esen, Ozlem; Esen, Ali Metin
Background: Response of systolic and diastolic velocities of mitral annulus to exercise in patients with subclinical hypothyroidism (SCH) has not been explored previously. We sought to investigate whether SCH is associated with abnormal left ventricular (LV) longitudinal function reserve to exercise. Methods: Mitral annular systolic (S') and early diastolic (E') velocities were measured at rest and during supine bicycle exercise using tissue Doppler echocardiography (TDE) in 23 patients with newly diagnosed SCH and 25 controls. LV diastolic and systolic longitudinal function reserve indices were calculated. Results: There were no significant differences in mitral inflow velocities at rest between groups except for LV end-diastolic dimension and LV end-systolic dimension, which were higher in the control group. E' and S' at rest were also similar between the groups. However, S' (9.8 +/- 1.5 vs. 11.3 +/- 1.5 cm/sec at 25 W, P = 0.001; and 11.3 +/- 1.8 vs. 13.1 +/- 1.8 cm/sec at 50 W, P = 0.001) and E' (13.8 +/- 1.4 vs. 15.7 +/- 1.6 cm/sec at 25 W, P = 0.001; and 15.6 +/- 1.6 vs. 18.2 +/- 1.5 cm/sec at 50 W, P < 0.001) during exercise were significantly lower in patients with SCH. Longitudinal systolic and diastolic function reserve indices were significantly lower in patients with SCH (systolic index, 1.4 +/- 0.9 vs. 2.5 +/- 0.9 cm/sec at 25 W, P = 0.001; and 2.7 +/- 1.3 vs. 4.1 +/- 1.2 cm/sec at 50 W, P = 0.001; diastolic index, 2.3 +/- 1.3 vs. 3.6 +/- 1.5 cm/sec at 25 W, P = 0.003; and 3.9 +/- 1.6 vs. 5.9 +/- 1.3 cm/sec at 50 W, P < 0.001). Conclusion: Assessment of LV longitudinal functional reserve with exercise using TDE appears to be helpful in identifying early myocardial dysfunction in SCH. (J Clin Endocrinol Metab 94: 2979-2983, 2009)
Absence of the Mecc Gene in Methicillin-Resistant Staphylococcus Aureus Isolated From Various Clinical Samples: the First Multi-Centered Study in Turkey
(Elsevier Science London, 2019) Cikman, Aytekin; Aydin, Merve; Gulhan, Baris; Karakecili, Faruk; Kurtoglu, Muhammet G.; Yuksekkaya, Serife; Ozekinci, Tuncer
Background: mecA is a predefined gene causing methicillin resistance in Staphylococcus aureus (S. aureus) isolates; however, it has been shown that some methicillin-resistant S. aureus (MRSA) strains do not carry this gene. Recently, in isolates found to be MRSA-positive but mecA-negative, a new resistance gene called mecC, which is a homolog of mecA, has been reported. This study aimed to investigate the mecC and mecA genes in MRSA strains isolated from different geographic regions in Turkey. Methods: The sample of the study consisted of 494 MRSA strains isolated from seven geographical regions in Turkey between 2013 and 2016. The strains were obtained from 17 centers, comprising 13 university hospitals, three education and research hospitals, and one state hospital. Methicillin resistance in S. aureus strains was determined using the agar disk diffusion method with a cefoxitin disk and the agar dilution method with oxacillin. The mecC and mecA genes in MRSA strains was investigated by Polymerase Chain Reaction (PCR). Results: Of the MRSA strains investigated, 47.9% were isolated from intensive care units. Concerning sample type, 36.7% were detected in the respiratory tract (tracheal aspirate, sputum, etc.), 24.8% in blood, 18.7% in skin and soft tissues, 9.3% in nasal swabs, 5.4% in urine, 4.1% in ears, and 1% in sterile body fluid. Using PCR, mecC was not identified in any of the S. aureus strains isolated from different clinical microbiology laboratories. mecA gene positivity was found in 315 of the MRSA strains (63.8%). Staphylococcal Cassette Chromosome mec ( SCCmec) type was identified in 232 strains (46.9%), of which 136 (58.7%) were type II, 75 (32.4%) were type IV, 12 (5.1%) were type Mb, six (2.5%) were type I, and three (1.3%) were type III. Conclusion: This is the first multi-centered study to investigate MRSA strains isolated from different regions in Turkey. The mecC gene was not detected in any of the MRSA strains. We believe that this study will constitute an important basis for monitoring possible future changes. (C) 2019 The Authors. Published by Elsevier Limited on behalf of King Saud Bin Abdulaziz University for Health Sciences.
Accelerated Atherosclerosis in Haemodialysis Patients; Correlation of Endothelial Function With Oxidative Dna Damage
(Oxford Univ Press, 2012) Kaya, Yuksel; Ari, Elif; Demir, Halit; Soylemez, Nihat; Cebi, Aysegul; Alp, Hakan; Beytur, Ali
Background. Accelerated atherosclerosis is the major cause of mortality in patients on chronic haemodialysis (HD). The aim of this study was to evaluate the relationship between oxidative DNA damage [8-hydroxy-2'-deoxyguanosine/deoxyguanosine ratio (8-OHdG/dG ratio)], oxidative stress biomarkers and endothelial function in HD patients as an indicator of atherosclerosis. Methods. Forty-four chronic HD patients without known atherosclerotic disease and 55 age- and sex-matched healthy individuals were included in the study. Plasma malondialdehyde (MDA) levels and 8-OHdG/dG ratio were determined as oxidative stress markers. Superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities were measured as antioxidants. Endothelial function was assessed by ultrasonography. Results. 8-OHdG/dG ratio and MDA levels were higher in HD patients than controls while SOD and GPx activities were lower in HD patients compared to controls. Flow-mediated dilatation FMD% in HD patients were lower than the control group (7.28 +/- 0.79 versus 11.18 +/- 0.82, P < 0.001). There was a significant negative correlation between FMD% and 8-OHdG/dG ratio (r = -0.678, P < 0.01) and MDA levels (r = 0.517, P < 0.01), while there was a significant positive correlation between FMD% and SOD (r = 0.538, P < 0.01) and GPx levels (r = 0.720, P < 0.01). Conclusions. Our data have demonstrated that HD patients exhibit increased oxidative DNA damage and decreased antioxidant activity. We propose that endothelial function is negatively correlated with 8-OHdG/dG ratio and positively correlated with antioxidant enzymes. To our knowledge, this is the first study to demonstrate the inverse relationship between endothelial function and plasma oxidative DNA damage in HD patients.
Accuracy of Early Pregnancy Diagnosis and Determining Pregnancy Loss Using Different Biomarkers and Machine Learning Applications in Dairy Cattle
(Elsevier Science inc, 2024) Ferraz, Priscila Assis; Poit, Diego Angelo Schmidt; Pinto, Leonardo Marin Ferreira; Guerra, Arthur Cobayashi; Neto, Adomar Laurindo; do Prado, Francisco Luiz; Pugliesi, Guilherme
This study aimed to compare the accuracy of IFN-tau stimulated gene abundance (ISGs) in peripheral blood mononuclear cells (PBMCs), CL blood perfusion by Doppler ultrasound (Doppler-US), plasma concentration of P4 on Day 21 and pregnancy-associated glycoproteins (PAGs) test on Day 25 after timed-artificial insemination (TAI) for early pregnancy diagnosis in dairy cows and heifers. Holstein cows (n = 140) and heifers (n = 32) were subjected to a hormonal synchronization protocol and TAI on Day 0. On Day 21 post-TAI, blood samples were collected for PBMC isolation and plasma concentration of P4. The CL blood perfusion was evaluated by Doppler- US. Plasma samples collected on Day 25 were assayed for PAGs. The abundance of ISGs ( ISG15 and RSAD2) ) in PBMCs was determined by RT-qPCR. Pregnancy was confirmed on Days 32 and 60 post-TAI by B-mode ultrasonography. Statistical analyses were performed by ANOVA using the MIXED procedure and GLIMMIX in SAS software. The pregnancy biomarkers were used to categorize the females as having undergone late luteolysis (LL); early embryonic mortality (EEM); late embryonic mortality (LEM); or late pregnancy loss (LPL). The abundance of ISGs, CL blood perfusion by Doppler-US, and concentrations of P4 on Day 21, and PAGs test on Day 25 were significant (P <0.05) predictors of early pregnancy in dairy cows and heifers. Dairy cows had a greater (P = 0.01) occurrence of LL than heifers, but there was no difference (P > 0.1) for EEM, LEM, and LPL in heifers compared to cows. Cows with postpartum reproductive issues had a greater (P = 0.008) rate of LEM and a lesser (P = 0.01) rate of LPL compared to cows without reproductive issues. In summary, the CL blood perfusion by Doppler-US had the highest accuracy and the least number of false negatives, suggesting it is the best predictor of pregnancy on Day 21 post-TAI. The PAGs test was the most reliable indicator of pregnancy status on Day 25 post- TAI in dairy heifers and cows. The application of machine learning, specifically the MARS algorithm, shows promise in enhancing the accuracy of predicting early pregnancies in cows.
Acoustic Radiation Force Impulse Imaging for Evaluation of Renal Parenchyma Elasticity in Diabetic Nephropathy
(Amer Roentgen Ray Soc, 2015) Goya, Cemil; Kilinc, Faruk; Hamidi, Cihad; Yavuz, Alpaslan; Yildirim, Yasar; Cetincakmak, Mehmet Guli; Hattapoglu, Salih
Objective: The goal of this study is to evaluate the changes in the elasticity of the renal parenchyma in diabetic nephropathy using acoustic radiation force impulse imaging. SUBJECTS AND METHODS. The study included 281 healthy volunteers and 114 patients with diabetic nephropathy. In healthy volunteers, the kidney elasticity was assessed quantitatively by measuring the shear-wave velocity using acoustic radiation force impulse imaging based on age, body mass index, and sex. The changes in the renal elasticity were compared between the different stages of diabetic nephropathy and the healthy control group. RESULTS. In healthy volunteers, there was a statistically significant correlation between the shear-wave velocity values and age and sex. The shear-wave velocity values for the kidneys were 2.87, 3.14, 2.95, 2.68, and 2.55 m/s in patients with stage 1, 2, 3, 4, and 5 diabetic nephropathy, respectively, compared with 2.35 m/s for healthy control subjects. Acoustic radiation force impulse imaging was able to distinguish between the different diabetic nephropathy stages (except for stage 5) in the kidneys. The threshold value for predicting diabetic nephropathy was 2.43 m/s (sensitivity, 84.1%; specificity, 67.3%; positive predictive value, 93.1%; negative predictive value 50.8%; accuracy, 72.1%; positive likelihood ratio, 2.5; and negative likelihood ratio, 0.23). CONCLUSION. Acoustic radiation force impulse imaging could be used for the evaluation of the renal elasticity changes that are due to secondary structural and functional changes in diabetic nephropathy.
Active Shrinkage Protects Neurons Following Axonal Transection
(Cell Press, 2023) Aydin, Mehmet Sxerif; Bay, Sadik; Yigit, Esra Nur; Ozgul, Cemil; Oguz, Elif Kaval; Konuk, Elcin Yenidunya; Ozturk, Gurkan
Trauma, vascular events, or neurodegenerative processes can lead to axonal injury and eventual transec(axotomy). Neurons can survive axotomy, yet the underlying mechanisms are not fully understood. Excessive water entry into injured neurons poses a particular risk due to swelling and subsequent death. Using in vitro and in vivo neurotrauma model systems based on laser transection and surgical nerve cut, demonstrated that axotomy triggers actomyosin contraction coupled with calpain activity. As a consequence, neurons shrink acutely to force water out through aquaporin channels preventing swelling and bursting. Inhibiting shrinkage increased the probability of neuronal cell death by about 3-fold. These studies reveal a previously unrecognized cytoprotective response mechanism to neurotrauma and offer fresh perspective on pathophysiological processes in the nervous system.
Activity of Pelargonium Quercetorum Agnew by Inducing Apoptosis-Like Cell Death on Non-Small Cell Lung Cancer Cell Lines
(Wiley-blackwell, 2014) Nazlihan, Aztopal; Yusuf, Yilmaz; Buse, Cevatemre; Mehmet, Sarimahmut; Ferda, Ari; Egemen, Dere; Engin, Ulukaya
Acute Effects of Methyl Parathion and Diazinon as Inducers for Oxidative Stress on Certain Biomarkers in Various Tissues of Rainbowtrout (Oncorhynchus Mykiss)
(Academic Press inc Elsevier Science, 2008) Isik, Ismail; Celik, Ismail
Present study aimed mainly to assess oxidative stress pesticides such as methyl parathion (MP) and diazinon, which are widely used insecticides and contaminate aquatic ecosystems, on certain biomarkers in various tissues of rainbowtrout (Oncorhynchcus mykiss). Biomarkers selected for stress monitoring were malondialdehyde (MDA) and antioxidant defense system (ADS) mainly reduced glutathione (GSH), glutathione reductase (GR), peroxidase (GSH-PX), transferase (GST) and superoxidedismutase (SOD) activities in the liver, gills and muscle of fishes exposed to 0.5 and 1 ppm dosages of MP and diazinon for 24,48 and 72 h. According to these results, after the administrations of MP and diazinon promote MDA content in some of the tissues of fishes treated with both dosages of MP and diazinon. With regard to the ADS, GSH-Px, GST, SOD, GR activities and GSH levels fluctuated after 24, 48 and 72 h in all the treatment groups compared with controls. Collective results demonstrated that exposure of fish to pesticides induced an increase in MDA joined with fluctuated ADS. This may reflect the potential role of these parameters as useful biomarkers for assessment of water pollution. (C) 2008 Elsevier Inc. All rights reserved.
Acute Immune Thrombocytopenic Purpura Following Combined Vaccine
(Wiley-blackwell, 2015) Akbayram, S.; Karaman, K.; Akbayram, H. T.; Garipardic, M.; Oner, A. F.
Acute Myeloid Leukemia in Elderly, Unfit Patients: Analysis of Turkish Aml Prospective Registry Database, on Behalf of Acute Leukemia Working Group of Turkish Society of Hematology
(Elsevier, 2023) Urlu, Selin Merih; Seval, Guldane Cengiz; Yucel, Elcin Erdogan; Mehtap, Ozgur; Yenihayat, Emel Merve; Polat, Merve Gokcen; Karakus, Volkan
Acute Peritoneal Dialysis in Critically Ill Newborns
(Springer, 2016) Ustyol, L.; Peker, E.; Demir, N.; Agengin, K.; Tuncer, O.
Acylated Flavone Glycosides From Veronica
(Pergamon-elsevier Science Ltd, 2003) Albach, DC; Grayer, RJ; Jensen, SR; Özgökce, F; Veitch, NC
A survey of the flavonoid glycosides of selected taxa in the genus Veronica yielded two new acylated 5,6,7,3',4'-pentahydroxyflavone (6-hydroxyluteolin) glycosides and two unusual allose-containing acylated 5,7,8,4'-tetrahydroxyflavone (isoscutellarein) glycosides. The new compounds were isolated from V. liwanensis and V. longifolia and identified using NMR spectroscopy as 6-hydroxyluteolin 4'-methyl ether 7-O-alpha-rhamnopyranosyl(1"'-->2")[6"-O-acetyl-beta-glucopyranoside] and 6-hydroxyluteolin 7-O-(6"-O -(E)-caffeoyl)-beta-glucopyranoside, respectively. Isoscutellarein 7-O-(6"'-O-acetyl)-beta-allopyranosyl(1'''--> 2")-beta-glucopyranoside was obtained from both V. intercedens and V. orientalis and its 4'-methyl ether from V. orientalis only. Complete H-1 and C-13 NMR spectral assignments are presented for both isoscutellarein glycosides. Two iridoid glucosides new to the genus Veronica (melittoside and globularifolin) were also isolated from V. intercedens. (C) 2003 Elsevier Ltd. All rights reserved.
An Adjustable Syringe Suction Drain
(Lippincott Williams & Wilkins, 2005) Tan, O; Atik, B; Parmaksizoglu, D
Adsorption of Malachite Green From Aqueous Solution Using Hydroxyethyl Starch Hydrogel Improved by Graphene Oxide
(Springer, 2022) Onder, Alper; Kivanc, Mehmet Riza; Durmus, Secil; Ilgin, Pinar; Ozay, Hava; Ozay, Ozgur
This study is the first report of the preparation of hydroxyethyl starch (HES) hydrogels rapidly crosslinked with divinyl sulfone in a single step and single pot. To develop the physical and chemical features of hydrogels, Graphene oxide (GO) nanoparticles were combined with the crosslinked HES. In addition to swelling studies, structural characterization of the samples was conducted with a scanning electron microscope (SEM) and transmission electron microscope (TEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffractometry (XRD), Brunauer-Emmett-Teller (BET) analysis and thermogravimetric analysis (TGA). For the removal of malachite green model dye by GO-HES, the effects of GO content, solution concentration, temperature, contact duration, dosage and pH on varying adsorption features were researched. Additionally, adsorption isotherms, kinetic and thermodynamic systematics were analyzed. The maximum adsorption capacity of GO-HES composite hydrogel was found to be 89.3 mg/g for Langmuir isotherm. The possible adsorption mechanism of the composite hydrogels for malachite green dye involved electrostatic, hydrogen bonding, and pi-pi interactions. In addition to reasonable cost and simple synthesis method, the prepared composite materials have potential use in wastewater treatment as adsorbents for the removal of dye from aqueous solutions due to efficient adsorption capacity.
Adsorption of Pb(Ii) Ions From Aqueous Solution by Native and Activated Bentonite: Kinetic, Equilibrium and Thermodynamic Study
(Elsevier, 2010) Kul, Ali Riza; Koyuncu, Huelya
In this study, the adsorption kinetics, equilibrium and thermodynamics of Pb(II) ions on native (NB) and acid activated (AAB) bentonites were examined. The specific surface areas, pore size and pore-size distributions of the samples were fully characterized. The adsorption efficiency of Pb(II) onto the NB and AAB was increased with increasing temperature. The kinetics of adsorption of Pb(II) ions was discussed using three kinetic models, the pseudo-first-order, the pseudo-second-order and the intra-particle diffusion model. The experimental data fitted very well the pseudo-second-order kinetic model. The initial sorption rate and the activation energy were also calculated. The activation energy of the sorption was calculated as 16.51 and 13.66 kJ mol(-1) for NB and AAB, respectively. Experimental results were also analysed by the Langmuir, Freundlich and Dubinin-Redushkevich (D-R) isotherm equations at different temperatures. R-L separation factor for Langmuir and the n value for Freundlich isotherm show that Pb(II) ions are favorably adsorbed by NB and AAB. Thermodynamic quantities such as Gibbs free energy (Delta G), the enthalpy (Delta H) and the entropy change of sorption (Delta S) were determined as about -5.06, 10.29 and 0.017 kJ mol(-1) K-1, respectively for AAB. It was shown that the sorption processes were an endothermic reactions, controlled by physical mechanisms and spontaneously. (c) 2010 Elsevier B.V. All rights reserved.

Browse

Browsing Van Yüzüncü Yıl Üniversitesi by WoS Q "Q1"