Hydrogen sorption characteristics of Zonguldak region coal activated by physical and chemical methods

Turkan Kopac,Atakan Toprak 한국화학공학회 2009 Korean Journal of Chemical Engineering Vol.26 No.6

Hydrogen sorption characteristics of activated carbons (ACs) produced by physical and chemical activations from two coal mines (Kilimli and Armutcuk) in the Zonguldak region, Turkey were investigated by a volumetric technique at 77 K. H2 adsorption isotherms were obtained on the samples exposed to pyrolytic thermal treatments in a temperature range of 600-900℃ under N2 flow and chemical activation using different chemical agents such as KOH, NH4Cl, ZnCl2 from the two mines. Experimental hydrogen adsorption isotherm data at 77 K were used for the evaluation of the adsorption isotherm constants of the Brunauer-Emmett-Teller (BET) and the Langmuir models, and also the amount of hydrogen adsorbed on the various samples was evaluated by using the adsorption isotherm data. Higher hydrogen adsorption capacity values were obtained for all the heat and the chemically treated activated carbon samples from the Kilimli coal samples than Armutcuk. The amount of H2 adsorbed on the original Kilimli coal samples was 0.020 wt%, and it was increased to 0.89 wt% on the samples pyrolyzed at 800℃. The highest value of hydrogen adsorption obtained was 1.2 wt% for the samples treated with KOH+NH4Cl mixture at 750℃ followed by oxidation with ZnCl2. It was shown that chemical activations were much more effective than physical activations in increasing the surface area, pore volume and the hydrogen sorption capacities of the samples.

Temperature and alkaline hydroxide treatment effects on hydrogen sorption characteristics of multi-walled carbon nanotube–graphite mixture

Turkan Kopac,Fatma Oguz Erdogan 한국공업화학회 2009 Journal of Industrial and Engineering Chemistry Vol.15 No.5

Temperature and alkaline hydroxide treatment effects on the surface area and pore structure of the cathode deposit multi-walled carbon nanotube (MWCNT)–graphite mixture were investigated in a temperature range of 600–800℃. Hydrogen sorption properties of the MWCNT–graphite mixture samples were studied by varying the alkaline hydroxide-activation temperature. Pore characterization of modified MWCNT–graphite mixture was performed with the observation of adsorption–desorption isotherms of N2 at 77 K. Hydrogen sorption of the non-treated and treated MWCNT–graphite mixture was carried out using a volumetric apparatus at 77 K. The highest surface area of the sample was obtained as 275 m2 g-1 by treatments with KOH at 600 ℃. The increase in the specific surface area of MWCNT–graphite sample mixture was about 13 times. Themaximum amount of hydrogen adsorbed on the MWCNT–graphite sample mixture was found as 0.75 and 0.54 wt.% by chemical treatments with KOH at 600℃ and NaOH at 700℃, respectively whereas it was 0.01 wt.% for the original sample. The hydrogen sorption capacity was enhanced considerably by KOH treatments at 600℃.

Cr(VI) removal using Fe₂O₃-chitosan-cherry kernel shell pyrolytic charcoal composite beads

Turkan Altun,Huseyin Ecevit 대한환경공학회 2020 Environmental Engineering Research Vol.25 No.3

In this study, cherry kernel shell pyrolytic charcoal was synthesized (CKSC) and composite beads were obtained by blending this pyrolytic charcoal with chitosan and Fe₂O₃ nanoparticles (Fe-C-CKSC). Cr(VI) adsorption from aqueous solutions by Fe-C-CKSC composite beads and CKSC adsorbents was studied comparatively. The effects of Cr(VI) initial concentration, adsorbent dosage, contact time, pH and temperature parameters on Cr(VI) adsorption were investigated. Adsorption reached an equilibrium point within 120 min for CKSC and Fe-C-CKSC adsorbents. The maximum Cr(VI) removal was obtained at the initial pH value of 1.56 for CKSC and 2.00 for Fe-C-CKSC. The optimum adsorbent dosage was found to be 5 g/L for CKSC and 3 g/L for Fe-C-CKSC. Based on the Langmuir model, the maximum adsorption capacities were calculated as 14.455 mg/g and 47.576 mg/g for CKSC and Fe-C-CKSC, respectively. Thermodynamic and kinetic studies were performed. As a result of adsorption kinetics calculations, adsorption was found to be consistent with the pseudo second order kinetic model. Characterization of the synthesized adsorbents was performed by SEM, BET, FTIR and elemental analysis. This study has shown that low cost adsorbents CKSC and Fe-C-CKSC can be used in Cr(VI) removal from aqueous solutions.

Current overview of the valorization of bio‑wastes for adsorbed natural gas applications

Turkan Kopac 한국탄소학회 2023 Carbon Letters Vol.33 No.6

The use of NG in the transportation sector is becoming an appealing option to diesel and gasoline fuels, presenting higher benefits. ANG technology offers a secure, cost-effective, energy-efficient strategy for the storage of NG in porous sorbents at reasonable gas densities. The major goal for its extensive utilization is the requirement of effective storage materials under practicable conditions. Recently, there has been increased attention in utilizing bio-wastes for the preparation of microporous carbons. In this contribution, our growing knowledge on the use of biobased materials and the processing strategies in an effort to predictively produce effective porous carbons appropriate for ANG technology have been reviewed. By careful literature selection, different precursors with different alternative processes to convert low-cost bio-wastes into porous carbons and achievements in methane storage are presented. To gain deeper insight into the technology, the correlation between the structural and chemical properties of materials and the factors affecting the storage performance are highlighted. The utilization of bio-wastes for the development of microporous carbons with facile methods emerged to be encouraging, which would be significant in larger scale applications. Bio-waste processing for ANG storage is valued over many other techniques, and the products are able to store substantial levels of methane. This review could help improve researchers’ evaluation of the methods as a guideline for ANG. Further studies for achieving an accomplished interconnection between the structural characteristics and the methane storage capacities with different bio-wastes and optimization strategies would be beneficial.

A Cyclin D1 (CCND1) Gene Polymorphism Contributes to Susceptibility to Papillary Thyroid Cancer in the Turkish Population

Aytekin, Turkan,Aytekin, Alper,Maralcan, Gokturk,Gokalp, M. Avni,Ozen, Dogukan,Borazan, Ersin,Yilmaz, Latif Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.17

Cyclin D1 is an important positive regulator of the G1/S phase of the cell cycle. We investigated the association between the CCND1 G870A polymorphism and susceptibility to papillary thyroid cancer in Turkish people. This study covered 102 patients with papillary thyroid cancer and 174 healthy controls. CCND1 genotyping was determined by the PCR-RFLP method. We found that the A allele frequency was higher in the cases than in the controls (p=0.042). On stratification analysis, papillary thyroid cancer risk was significantly elevated in individuals older than 45 years with the A allele (OR=1.91, 95% CI, 1.09-3.35, p=0.024) and in females with the A allele (OR=1.73, 95% CI, 1.06-2.84, p=0.029), compared to the G allele. According to the subject age, there was an increased papillary thyroid cancer risk for the individuals older than 45 years with the AA genotype (OR=2.28, 95% CI, 1.02-5.13, p=0.046) compared to the AG+GG combined genotypes. In conclusion, it is suggested that the CCND1 G870A polymorphism may contribute to the susceptibility to papillary thyroid cancer, especially in those who were older subjects ($45{\leq}$ years old) and female, in the Turkish population.

Life Story of Dr. Hulusi Behcet

Saylan, Turkan Yonsei University, College of Medicine 1997 Yonsei medical journal Vol.38 No.6

A Comparative Study on Electrical Characteristics of Crystalline AlN Thin Films Deposited by ICP and HCPA-Sourced Atomic Layer Deposition

Halit Altuntas,Turkan Bayrak 대한금속·재료학회 2017 ELECTRONIC MATERIALS LETTERS Vol.13 No.2

In this work, we aimed to investigate the effects of two different plasma sourceson the electrical properties of low-temperature plasma-assisted atomic layerdeposited (PA-ALD) AlN thin films. To compare the electrical properties,50 nm thick AlN films were grown on p-type Si substrates at 200 °C by usingan inductively coupled RF-plasma (ICP) and a stainless steel hollowcathode plasma-assisted (HCPA) ALD systems. Al/AlN/p-Si metal-insulatorsemiconductor(MIS) capacitor devices were fabricated and capacitance versusvoltage (C-V) and current-voltage (I-V) measurements performed to assess thebasic important electrical parameters such as dielectric constant, effectivecharge density, flat-band voltage, breakdown field, and threshold voltage. Inaddition, structural properties of the films were presented and compared. Theresults show that although HCPA-ALD deposited AlN thin films hasstructurally better and has a lower effective charge density (Neff) value thanICP-ALD deposited AlN films, those films have large leakage current, lowdielectric constant, and low breakdown field. This situation was attributed tothe involvement of Si atoms into the AlN layers during the HCPA-ALDprocessing leads to additional current path at AlN/Si interface and might impairthe electrical properties. PACS: 73.30.+y: 73.40.Qv: 73.40.Ns

Is the Loop Electrosurgical Excision Procedure Necessary for Minor Cervical Cytological Abnormalities?

Aksan-Desteli, Guldeniz,Gursu, Turkan,Baykal, Cem Murat Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.1

Background: To investigate the indications of loop electrosurgical excision procedure (LEEP) and its overtreatment rates for the see and treat and three step strategies in cases of atypical squamous cells of undetermined cytology (ASC-US) and low grade intraepithelial neoplasia (LGSIL) cytology. Materials and Methods: We retrospectively analyzed colposcopy directed biopsy (CDB) and LEEP results of 176 paients with ASC-US or LGSIL cytologies who underwent colposcopic examination. Results: Initial cytologies were ASCUS in 120 women and LGSIL in 56. According to the see and treat approach immediate LEEP was performed for38 women. Among the remaining 138 women, LEEP was performed for 32 whose CDB results revealed CIN2/3 lesions. In the see and treat group the recognition of CIN2/3 was found to be 39.4%. The overtreatment rate was 60% as compared to 25% in the three step group. In CDB group detection of CIN 2 or greater lesions increased with 3 or more biopsies. Conclusions: In patients with ASC-US/LGSIL cytologies CDB should be performed before LEEP to prevent overtreatment, with attention to all suspected areas and more than 2 biopsies taken.

Deploying root microbiome of halophytes to improve salinity tolerance of crops

Turgut Yigit Akyol,Shusei Sato,Ismail Turkan 한국식물생명공학회 2020 Plant biotechnology reports Vol.14 No.2

Salinization of the soils is one of the most prominent problems threatening global food security. Root microbiome engineering using biofertilizers provides a sustainable way to increase agricultural productivity. Halophytes, which are extremely salt-tolerant plants, can tolerate up to 1300 mM NaCl. Members of the halophytic root microbiome now provide a promising solution to meet the increased demand in the agricultural output. Here, we explore the members of this microbiome and explain the plant growth-promoting functions of them. We discuss the manipulation of the root microbiome with synthetic microbial communities including keystone microorganisms of the halophytic root microbiome. Importantly, we provide a simple method in R software to fi nd these putative keystone taxa using network analysis. We believe this strategy will provide a valuable tool for future studies performing the combined investigation of the root bacteria and fungi of halophytes.

Increased UGT1A3 and UGT1A7 Expression is Associated with Pancreatic Cancer

Yilmaz, Latif,Borazan, Ersin,Aytekin, Turkan,Baskonus, Ilyas,Aytekin, Alper,Oztuzcu, Serdar,Bozdag, Zehra,Balik, Ahmet Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.4

UGT1A play important roles in the glucuronidation of a variety of endogenous and exogenous compounds. UGT1A isoforms are expressed tissue specifically. The aim of this study was to examine the relationship between UGT1A3 and UGT1A7 mRNA expression and pancreatic cancer. Paired healthy and tumor tissue samples of 43 patients with pancreatic cancer were included in this study. UGT1A3 and UGT1A7 mRNA expressions were analyzed by real time-PCR. In the result of study, UGT1A3 and UGT1A7 mRNA expressions were significantly higher in tumor tissue than normal tissue of pancreatic cancer patients (p<0.05). In addition, high mRNA expression of UGT1A3 and UGT1A7 was significantly associated with larger tumor size (p<0.05). The data suggested that UGT1A3 and UGT1A7 may play roles in the progression of pancreatic cancer. Consequently, UGT1A3 and UGT1A7 are potential prognostic indicators.