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Öğe Algae and Their Metabolites as Potential Bio-Pesticides(MDPI, 2022) Asimakis, Elias; Shehata, Awad A.; Eisenreich, Wolfgang; Acheuk, Fatma; Yılmaz, MeteAn increasing human population necessitates more food production, yet current techniques in agriculture, such as chemical pesticide use, have negative impacts on the ecosystems and strong public opposition. Alternatives to synthetic pesticides should be safe for humans, the environment, and be sustainable. Extremely diverse ecological niches and millions of years of competition have shaped the genomes of algae to produce a myriad of substances that may serve humans in various biotechnological areas. Among the thousands of described algal species, only a small number have been investigated for valuable metabolites, yet these revealed the potential of algal metabolites as bio-pesticides. This review focuses on macroalgae and microalgae (including cyanobacteria) and their extracts or purified compounds, that have proven to be effective antibacterial, antiviral, antifungal, nematocides, insecticides, herbicides, and plant growth stimulants. Moreover, the mechanisms of action of the majority of these metabolites against plant pests are thoroughly discussed. The available information demonstrated herbicidal activities via inhibition of photosynthesis, antimicrobial activities via induction of plant defense responses, inhibition of quorum sensing and blocking virus entry, and insecticidal activities via neurotoxicity. The discovery of antimetabolites also seems to hold great potential as one recent example showed antimicrobial and herbicidal properties. Algae, especially microalgae, represent a vast untapped resource for discovering novel and safe biopesticide compounds.Öğe A review of critical residential buildings parameters and activities when investigating indoor air quality and pollutants(Wiley, 2022) Teresa Baeza-Romero, Maria; Dudzinska, Marzenna R.; Torkmahalleh, Mehdi Amouei; Barros, Nelson; Gazioğlu Rüzgar, DuyguIndoor air in residential dwellings can contain a variety of chemicals, sometimes present at concentrations or in combinations which can have a negative impact on human health. Indoor Air Quality (IAQ) surveys are often required to characterize human exposure or to investigate IAQ concerns and complaints. Such surveys should include sufficient contextual information to elucidate sources, pathways, and the magnitude of exposures. The aim of this review was to investigate and describe the parameters that affect IAQ in residential dwellings: building location, layout, and ventilation, finishing materials, occupant activities, and occupant demography. About 180 peer-reviewed articles, published from 01/2013 to 09/2021 (plus some important earlier publications), were reviewed. The importance of the building parameters largely depends on the study objectives and whether the focus is on a specific pollutant or to assess health risk. When considering classical pollutants such as particulate matter (PM) or volatile organic compounds (VOCs), the building parameters can have a significant impact on IAQ, and detailed information of these parameters needs to be reported in each study. Research gaps and suggestions for the future studies together with recommendation of where measurements should be done are also provided.Öğe A stochastic approach for the assessment of suspended sediment concentration at the Upper Rhone River basin, Switzerland(Springer, 2022) Vaheddoost, Babak; Vazifehkhah, Saeed; Safari, Mir Jafar SadeghThis study addresses the link between suspended sediment concentration, precipitation, streamflow, and direct runoff components. This is important since suspended sediment concentration in the streamflow has invaluable importance in the management of the river basin. For this, the daily streamflow time series in five consecutive stations at Upper Rhone River Basin, a relatively large basin in the Alpine region of Switzerland, daily precipitation at one station, and the twice a week suspended sediment concentration records at the most downstream station between January 1981 and October 2020 are used. Initially, the base flow and the direct runoff associated with streamflow time series are obtained using the sliding interval method. Elasticity analyses between streamflow and suspended sediment concentration together with correlation, autocorrelation, partial autocorrelation, stationarity, and homogeneity are examined by the Augmented Dickey-Fuller and Pettitt's tests, respectively. Then, various stochastic scenarios are generated using the autoregressive moving average exogenous method (ARMAX). It is concluded that the precipitation and direct runoff have fewer effects on the suspended sediment concentration at downstream of the river. Hence, the cumulative effect of the glacier or snowmelt and channel erosion may exceed the effect of rain blown washouts on the suspended sediment concentration at the Port du Scex station. It is found that the ARMAX model results are satisfactory and can be suggested for further application.Öğe Analysis of cyber security knowledge gaps based on cyber security body of knowledge(Springer, 2023) Catal, Cagatay; Ozcan, Alper; Donmez, Emrah; Kaşif, AhmetDue to the increasing number of cyber incidents and overwhelming skills shortage, it is required to evaluate the knowledge gap between cyber security education and industrial needs. As such, the objective of this study is to identify the knowledge gaps in cyber security graduates who join the cyber security workforce. We designed and performed an opinion survey by using the Cyber Security Knowledge Areas (KAs) specified in the Cyber Security Body of Knowledge (CyBOK) that comprises 19 KAs. Our data was gathered from practitioners who work in cyber security organizations. The knowledge gap was measured and evaluated by acknowledging the assumption for employing sequent data as nominal data and improved it by deploying chi-squared test. Analyses demonstrate that there is a gap that can be utilized to enhance the quality of education. According to acquired final results, three key KAs with the highest knowledge gap are Web and Mobile Security, Security Operations and Incident Management. Also, Cyber-Physical Systems (CPS), Software Lifecycles, and Vulnerabilities are the knowledge areas with largest difference in perception of importance between less and more experienced personnel. We discuss several suggestions to improve the cyber security curriculum in order to minimize the knowledge gaps. There is an expanding demand for executive cyber security personnel in industry. High-quality university education is required to improve the qualification of upcoming workforce. The capability and capacity of the national cyber security workforce is crucial for nations and security organizations. A wide range of skills, namely technical skills, implementation skills, management skills, and soft skills are required in new cyber security graduates. The use of each CyBOK KA in the industry was measured in response to the extent of learning in university environments. This is the first study conducted in this field, it is considered that this research can inspire the way for further researches.Öğe A change is gonna come: will traditional meat production end?(Springer, 2022) Simdi, Halil; Şeker, AyberkRecently, the world has faced environmental disasters mainly due to global warming. One of the main reasons for global temperature imbalances is the greenhouse gases (GHG) that soar the atmosphere's heat. The major aim of the current study is to explore whether the livestock population is the main contributor to GHG emission through econometric estimations. In this study, we examine the impact of livestock population with other explanatory variables-GDP per capita, Economic Complexity Index (ECI), ecological balance, and total patent applications-over GHG emission of 25 countries responsible for 76% of GHG emission between 1990 and 2017. To investigate the relationship of variables, Fully modified ordinary least squares (FMOLS) and dynamic ordinary least squares (DOLS) are used, as well as panel causality. Also, the relationship is examined by using the responsiveness scores (RS) approach. The empirical results reveal that all variables have a causal relationship with GHG emission. GDP per capita, ECI, and livestock population enhance the GHG emission whereas square of GDP per capita and ecological balance decline the environmental degradation. The paper demonstrates that the environmental Kuznets curve is valid and supports the literature. Lastly, the RS estimation results reveal that the livestock population is causing higher GHG emissions for all countries in the analysis, contrary to other independent variables. Governments should promote carbon-neutral meat production facilities instead of traditional beef farms to live in a more sustainable world. In the future, countries that invest in research and development (R&D) for less emission meat production will have a comparative advantage in the sustainable international meat market.Öğe A Monte Carlo investigation of some important radiation parameters and tissue equivalency for photons below 1 keV in human tissues(IOP Publishing Ltd, 2022) Rafiei, Mustafa Mohammad; Parsaei, Sara; Kaur, Parminder; Singh, K. J.; Büyükyıldız, Mehmet; Kurudirek, MuratThe attenuation coefficients are important input values in estimating not only the dose and exposure in radiotherapy and medical imaging, but also in the proper design of photon shields. While studies are widely available above 1 keV, the attenuation coefficients of human tissues for photon energies less than 1 keV have not been studied yet. In this study, the attenuation coefficients of water and some human tissues were estimated for low energy photons using the MCNP6.1 code in the energy region 0.1 keV-1 keV. Mass attenuation coefficients were estimated at photon energies of 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950 and 1000 eV for water and ten human tissues (Soft, Breast, Lung, Bone, Brain, Eye lens, Ovary, Skin, Thyroid and Prostate). Results were compared with those available in literature and a fairly good agreement has been obtained. These data were then used to calculate the mean free path, half value layer, tenth value layer, effective atomic number and specific gamma-ray constant (useful for calculation of dose rate) as well. Moreover, for comparison the effective atomic number of the water has been obtained using the results of this work and using the data available in NIST database from 0.1 to 1 keV. In addition, the human tissues were compared with some tissue equivalent materials in terms of effective atomic number and specific gamma-ray constant to study the tissue equivalency from the results, the muscle-equivalent liquid with sucrose has been found to be the best tissue equivalent material for soft tissue, eye lens and brain with relative difference below 4.1%.Öğe Co-loading of Temozolomide with Oleuropein or rutin into polylactic acid core-shell nanofiber webs inhibit glioblastoma cell by controlled release.(Elsevier B.V., 2023-12-31) Ercelik, Melis; Tekin, Cagla; Parın, Fatma Nur; Mutlu, Büşra; Dogan, Hazal Yilmaz; Tezcan, Gulcin; Aksoy, Secil Ak; Gurbuz, Melisa; Yıldırım, Kenan; Bekar, Ahmet; Kocaeli, Hasan; Taskapilioglu, Mevlut Ozgur; Eser, Pinar; Tunca, BerrinGlioblastoma (GB) has susceptibility to post-surgical recurrence. Therefore, local treatment methods are required against recurrent GB cells in the post-surgical area. In this study, we developed a nanofiber-based local therapy against GB cells using Oleuropein (OL), and rutin and their combinations with Temozolomide (TMZ). The polylactic acid (PLA) core-shell nanofiber webs were encapsulated with OL (PLA), rutin (PLA), and TMZ (PLA) by an electrospinning process. A SEM visualized the morphology and the total immersion method determined the release characteristics of PLA webs. Real-time cell tracking analysis for cell growth, dual Acridine Orange/Propidium Iodide staining for cell viability, a scratch wound healing assay for migration capacity, and a sphere formation assay for tumor spheroid aggressiveness were used. All polymeric nanofiber webs had core-shell structures with an average diameter between 133 ± 30.7-139 ± 20.5 nm. All PLA webs promoted apoptotic cell death, suppressed cell migration, and spheres growth (p < 0.0001). PLA and PLA suppressed GB cell viability with a controlled release that increased over 120 h, while PLA caused rapid cell inhibition (p < 0.0001). Collectively, our findings suggest that core-shell nano-webs could be a novel and effective therapeutic tool for the controlled release of OL and TMZ against recurrent GB cells.Öğe Symmetrical and Asymmetrical Thiophene-Coumarin-Based Organic Semiconductors(American Chemical Society, 2023) Altınışık, Sinem; Özdemir, Mücahit; Kortun, Arzu; Zorlu, Yunus; Yalçın, Bahattin; Köksoy, Baybars; Koyuncu, SermetOrganic semiconductors are a valuable material class for optoelectronic applications due to their electronic and optical properties. Four new symmetric and asymmetric thiophene-coumarin derivatives were designed and synthesized via Pd-catalyzed Suzuki and Stille Cross-Coupling reactions. Single crystals of all synthesized thiophene-coumarin derivatives were obtained, and π···π interactions were observed among them. The π···π interactions were supported by UV-vis, transmission electron microscopy, and atomic force microscopy analyses. The photophysical and electrochemical properties of the coumarins were investigated and supported by density functional theory studies. Fluorescence quantum yields were recorded between 36 and 66%. Moreover, mega Stokes shifts (175 nm or 8920 cm) were observed in these new chromophore dyes. The emission and absorption colors of the thiophene-coumarin compounds differed between their solution and film forms. Electrochemically, the highest occupied molecular orbital levels of the coumarins increased with the 3,4-ethylenedioxythiophene group, leading to a narrowing of the band gap, while the phenyl bridge weakened the donor-acceptor interaction, expanding the band gap.Öğe An ecological restoration assessment integrating multi-criteria decision analysis with landscape sensitivity analysis for a hydroelectric power plant project: the Tokat-Niksar case(Springer Science and Business Media Deutschland GmbH, 2021) Demir, Sara; Demirel, Ö.; Okatan, A.Due to Turkey’s reliance on imported electricity, it has been using hydroelectric power plants (HPPs) to cover some of its electrical energy needs since 2011. However, HPP projects, which do not take landscape sensitivity into account, cause the ecological integrity of the basins and the ecosystem structure to deteriorate. This study presents the Tokat-Niksar HPP project field example in Turkey’s Central Black Sea region with its steep slopes, rich forest and creek vegetation, protected endemic plants and wildlife, cultural heritage dating back to 3000 BC agricultural activities, and long-established local culture. The study, in fact, aims to develop a landscape restoration plan that considers the sensitivity of landscapes in the HPP project area. For this purpose, a landscape sensitivity analysis consisting of water, habitat, visibility, erosion functions, and multi-criteria decision analysis (MCDA) determining priority of functions conducted with experts were performed. According to the results, the water function was found to have the highest, and the visibility the lowest priority in the ranking. Consequently, 1st, 2nd, 3rd, and 4th-degree sensitive areas with very high, high, and moderate landscape sensitivity were determined by weighted sum function by considering the priority of each landscape function, and accordingly, a five-stage landscape restoration model was developed including soil protection, areas to be protected, erosion control, vegetation screening, and creek reclamation. This study presents a framework for sustainable landscape restoration solutions in the town by combining landscape sensitivity analysis via MCDA.Öğe Senkron relüktans motorun gözlemci tabanlı sensörsüz kontrolü(BTÜ, Fen Bilimleri Enstitüsü, 2021) Cebeci, Emre; Yaşa, YusufSenkron relüktans motorlar, relüktans momenti prensibiyle mekanik enerji üretebilen elektrik makineleridir. Rotorunda herhangi bir sargı ve mıknatıs bulundurmadığından dolayı ucuz ve sağlam yapıya sahiptir. Bu sebeplerden dolayı keşfi daha önceki zamanlara dayansa da güç elektroniği ve kontrol yöntemlerindeki gelişmelerden dolayı son zamanlarda popüler hâle gelmiştir. Senkron relüktans motor; asenkron motor gibi sabit hız uygulamaları için direkt şebekeye bağlanamamakta, motor sürücü devresi gerektirmektedir. Motor sürücü devresi, gerekli anahtarlamaları yapabilmesi için rotor açısal konumuna ihtiyaç duymaktadır. Kontrol yöntemleri konum sensörlü ve sensörsüz olmak üzere ikiye ayrılmaktadır. Bu tez çalışmasında sensörsüz olarak senkron relüktans motor kontrol edilmiştir. Sensörsüz kontrol yönteminde daha önce tüm alternatif akımlı makineler için önerilen aktif akı kavramının prensibi ile rotor açısal konumu tahmin edilmektedir. Aktif akı vektörü ile rotor konumu tahmininde daha önce önerilen yöntemlerden farklı olarak aktif akı vektörünü diferansiyel denklemlerine ayırarak durum uzay denklem kümesi oluşturulmuştur. Oluşturulan durum uzay denklemlerine uygun Kokusuz Kalman Filtresi (UKF) tasarlanmıştır. UKF sayesinde aktif akı vektör bileşenleri tahmin edilmiştir. Bileşenler sayesinde rotor açısal konumu tahmin edilmiştir. Diğer aktif akı ile rotor açısal konumu tahmin yöntemlerinden farkı, içeriğinde herhangi bir integrator veya Faz Kilitli Döngü (PLL) bulundurmamasıdır. UKF ile tahmin edilen rotor açısal konum değeri kullanılarak motor elektriksel parametreleri Park Dönüşümü ile dönen eksen takımına dönüştürülmektedir. Dönen eksen takımında oluşturulan senkron relüktans motor dinamik denklemleri için Genişletilmiş Kalman Filtresi (EKF) tasarlanmıştır. Tasarlanan EKF ile rotor açısal hızı ve yük torku tahmin edilebilmektedir. Tahmin edilen rotor açısal hızı, diğer tahmin yöntemlerindeki tahmin değerleri ile karşılaştırılmış, EKF ile tahmin edilen rotor açısal hız hatasının diğer yöntemlere göre %70 oranında daha az olduğu gözlemlenmiştir. Tahmin edilen rotor açısal konum, hız ve yük torku değerleri için alan yönlendirmeli kontrol yöntemleri uygulanarak senkron relüktans motor kontrol edilmiştir. Bahsedilen kontrol basamakları bilgisayar ortamında benzetim çalışması yapıldıktan sonra test düzeneğinde kontrol edilmiştir. Test düzeneğindeki sürücü kartında diğer güç anahtarlarına nazaran daha iyi performans sergileyen silisyum karbür (SiC) tip mosfetler kullanılmıştır. Bu Şekilde devre ve sistemin performansı artırılmıştır.Öğe Gas phase polymerization of ethylene towards UHMWPE(2020) Geçim, Gözde; Erkoç, ErtuğrulFor the first time, ultra-high molecular weight polyethylene (UHMWPE) was produced in gas phase process with a new fluidized bed concept where the solids are dispersed phase and the gas is bulk phase as opposed to conventional fluidized bed reactors (FBRs). With this concept, UHMWPE with average molecular weights about 1-6,9 × $10^6$ g moles ?1 were produced with a commercial supported Ziegler-Natta catalyst by using a gas phase mini semibatch reactor system. Additionally, optimum conditions of gas phase polymerization for the best results of productivity, catalyst activity, molecular weight and crystallinity were determined by Taguchi experimental design and catalyst stability at the optimum condition was tested by video microscopy polymerization. The characterization of products was carried out experimentally by TGA, DSC, FTIR, and NMR.Öğe Selected Persistent Organic Pollutants in Ambient Air in Turkey: Regional Sources and Controlling Factors(American Chemical Society, 2021) Gungormus, E.; Sofuoglu, A.; Celik, H.; Gedik, K.; Mulder, M.D.; Lammel, G.; Birgül, AşkınAs a result of its unique location, Turkey receives air masses from Europe, Russia, Middle East, and Africa, making it an important place in terms of long-range atmospheric transport (LRT) of contaminants. Atmospheric levels of 22 organochlorine pesticides (OCPs), 45 polychlorinated biphenyls (PCBs), and 14 polybrominated diphenyl ethers (PBDEs) were measured in two metropolitan cities, Istanbul and Izmir, on a weekly basis from May 2014 to May 2015. Dichlorodiphenyltrichloroethane (DDT) and its derivatives were dominant OCP species, followed by isomers of hexachlorocyclohexane (HCH) at both sites. The annual mean concentration of ?DDX (sum of o,p?-DDT, p,p?-DDT, o,p?-DDD, p,p?-DDD, o,p?-DDE, and p,p?-DDE) was 82 pg/m3 for Istanbul and 89 pg/m3 for Izmir, while these levels were about 46 pg/m3 for ?HCHs (sum of ?-, ?-, ?-, and ?-HCH) at both of the sites. At both stations, tri- and tetra-PCBs and tetra- and penta-PBDEs were dominant congeners. The temperature dependence indicates that both LRT and local contaminated areas contribute to the elevated levels. A Lagrangian particle dispersion model (FLEXPART) showed a few potential source regions in northern Africa and Middle East, southern-southwestern and eastern Europe including Russia, as well as from local domestic metropolitan areas. © 2021 American Chemical Society.Öğe Author Correction: Demonstration of Container Efects on Recognition Process of Liquids Using a RingResonator Measurement Method(Nature Research, 2020) Öztürk, TurgutThe Acknowledgements section in this Article was omitted. The Acknowledgements section should read: “The author thanks İlhami Ünal and Aysun Sayıntı for providing the measurement data made at Marmara Research Center of TUBITAK.” © 2020, The Author(s).Öğe Antibacterial activity of combination of synthetic and biopolymer non-woven structures(Walter de Gruyter GmbH, 2015) Bhullar, Sukhwinder Kaur; Özsel Kaya, Burçak; Yadav, R.; Kaur, G.; Chintamaneni, M.; Buttar, H.S.Background: Fibrous structures and synthetic polymer blends offer potential usages in making biomedical devices, textiles used in medical practices, food packaging, tissue engineering, environmental applications and biomedical arena. These products are also excellent candidates for building scaffolds to grow stem cells for implantation, to make tissue engineering grafts, to make stents to open up blood vessels caused by atherosclerosis or narrowed by blood clots, for drug delivery systems for micro- to nano-medicines, for transdermal patches, and for healing of wounds and burn care. The current study was designed to evaluate the antimicrobial activity of woven and non-woven forms of nano- and macro-scale blended polymers having biocompatible and biodegradable characteristics. Methods: The antimicrobial activity of non-woven fibrous structures created with the combination of synthetic and biopolymer was assessed using Gram-negative, Gram-positive bacteria, such as Staphylococcus aureus, Proteus vulgaris, Escherichia coli and Enterobacter aerogenes using pour plate method. Structural evaluation of the fabricated samples was performed by Fourier transform infrared spectroscopy. Results: Broad spectrum antibacterial activities were found from the tested materials consisting of polyvinyl alcohol (PVA) with chitosan and nylon-6 combined with chitosan and formic acid. Conclusions: The combination of PVA with chitosan was more bactericidal or bacteriostatic than that of nylon-6 combined with chitosan and formic acid. PVA combination with chitosan appears to be a broad-spectrum antimicrobial agent. © 2015 by De Gruyter 2015.Öğe An alginate-poly(acrylamide) hydrogel with TGF-?3 loaded nanoparticles for cartilage repair: Biodegradability, biocompatibility and protein adsorption(Elsevier B.V., 2021) Saygili, E.; Kaya, E.; Ilhan-Ayisigi, E.; Saglam-Metiner, P.; Alarcin, E.; Kazan, Aslıhan; Girgic, E.Current implantable materials are limited in terms of function as native tissue, and there is still no effective clinical treatment to restore articular impairments. Hereby, a functionalized polyacrylamide (PAAm)-alginate (Alg) Double Network (DN) hydrogel acting as an articular-like tissue is developed. These hydrogels sustain their mechanical stability under different temperature (+4 °C, 25 °C, 40 °C) and humidity conditions (60% and 75%) over 3 months. As for the functionalization, transforming growth factor beta-3 (TGF-?3) encapsulated (NPTGF-?3) and empty poly(lactide-co-glycolide) (PLGA) nanoparticles (PLGA NPs) are synthesized by using microfluidic platform, wherein the mean particle sizes are determined as 81.44 ± 9.2 nm and 126 ± 4.52 nm with very low polydispersity indexes (PDI) of 0.194 and 0.137, respectively. Functionalization process of PAAm-Alg hydrogels with ester-end PLGA NPs is confirmed by FTIR analysis, and higher viscoelasticity is obtained for functionalized hydrogels. Moreover, cartilage regeneration capability of these hydrogels is evaluated with in vitro and in vivo experiments. Compared with the PAAm-Alg hydrogels, functionalized formulations exhibit a better cell viability. Histological staining, and score distribution confirmed that proposed hydrogels significantly enhance regeneration of cartilage in rats due to stable hydrogel matrix and controlled release of TGF-?3. These findings demonstrated that PAAm-Alg hydrogels showed potential for cartilage repair and clinical application. © 2021 Elsevier B.V.Öğe A test of improved force field parameters for urea: molecular-dynamics simulations of urea crystals(Springer, 2012) Altınbaş Özpınar, Gül; Beierlein, Frank R.; Peukert, Wolfgang; Zahn, Dirk; Clark, TimothyMolecular-dynamics (MD) simulations of urea crystals of different shapes (cubic, rectangular prismatic, and sheet) have been performed using our previously published force field for urea. This force field has been validated by calculating values for the cohesive energy, sublimation temperature, and melting point from the MD data. The cohesive energies computed from simulations of cubic and rectangular prismatic urea crystals in vacuo at 300 K agreed very well with the experimental sublimation enthalpies reported at 298 K. We also found very good agreement between the melting points as observed experimentally and from simulations. Annealing the crystals just below the melting point leads to reconstruction to form crystal faces that are consistent with experimental observations. The simulations reveal a melting mechanism that involves surface (corner/edge) melting well below the melting point, and rotational disordering of the urea molecules in the corner/edge regions of the crystal, which then facilitates the translational motion of these molecules.Öğe A DFT study on the [VO](1+)-ZSM-5 cluster: direct methanol oxidation to formaldehyde by N2O(Royal Soc Chemistry, 2013) Fellah, Mehmet Ferdi; Onal, IsikThe mechanism of direct oxidation of methanol to formaldehyde by N2O has been theoretically investigated by means of density functional theory over an extra framework species in ZSM-5 zeolite represented by a [(SiH3)(4)AlO4](1) [V-O](1+) cluster model. The catalytic reactivity of these species is compared with that of mononuclear (Fe-O)(1+) sites in ZSM-5 investigated in our earlier work at the same level of theory (J. Catal. 2011, 282, 191). The [V-O](1+) site in ZSM-5 zeolite shows an enhanced catalytic activity for the reaction. The calculated vibrational frequencies for grafted species on vanadium sites on the surface are in good agreement with the experimental values. According to the theoretical results obtained in this study the [V-O](1+) site in the ZSM-5 catalyst has an important role in the direct catalytic oxidation of methanol to formaldehyde by N2O.Öğe Radiation transmission of colemanite, tincalconite and ulexite for 6 and 18 MV X-rays by using linear accelerator(Pergamon-Elsevier Science Ltd, 2013) Demir, Faruk; Un, AdemTincalconite, ulexite and colemanite are boron ores. Since these ores include boron, hydrogen and many other elements, these boron ores may be used as shielding materials instead of Pb metal and paraffin wax. In this study, measurements have been made to determine radiation transmission of tincalconite, ulexite and colemanite by transmission method for 6 and 18 MV using linear accelerator (LINAC) with ionization chamber. The experimental results were compared to the results of WinXCom X-ray computer program's. In pair production region, ores such as colemanite, ulexite and tincalconite can be preferred as shielding materials to prevent photon and neutron particle radiations. (C) 2012 Elsevier Ltd. All rights reserved.Öğe Determination of mass attenuation coefficients, effective atomic numbers and effective electron numbers for heavy-weight and normal-weight concretes(Pergamon-Elsevier Science Ltd, 2013) Un, Adem; Demir, FarukTotal mass attenuation coefficients, effective atomic numbers and effective electron numbers values for different 16 heavy-weight and normal-weight concretes are calculated in the energy range from 1 keV to 100 GeV. The values of mass attenuation coefficients used in calculations are taken from the WinXCom computer program. The obtained results for heavy-weight concretes are compared with the results for normal-weight concretes. The results of heavy-weight concretes fairly differ from results for normalweight concretes. (C) 2013 Elsevier Ltd. All rights reserved.Öğe Cycloartane glycosides from Astragalus plumosus var. krugianus and evaluation of their antioxidant potential(Elsevier, 2014) Denizli, Nilufer; Horo, Ibrahim; Gulcemal, Derya; Masullo, Milena; Festa, Michela; Koz, ÖmerThe methanol extracts of Astragalus plumosus var. krugianus Chamb. & Matthews afforded sixteen cycloartane glycosides among which krugianoside A, was never reported before. All compounds were evaluated for their cytotoxic activity in human skin fibroblast WS1 cells. For compounds exhibiting no significant effect on WS1 viability, the antioxidant potential was examined. Compounds 1 and 8 prevented elevation of ROS induced by t-BOOH, suggesting the potential activity of these compounds to protect fibroblasts from oxidative stress. (C) 2013 Elsevier B.V. All rights reserved.
