Bulunan: 73 Adet 0.001 sn
Koleksiyon [4]
Tam Metin [1]
Yazar [20]
Yayın Türü [3]
Konu Başlıkları [20]
Yayın Tarihi [9]
Dergi Adı [20]
Yayıncı [1]
Dil [1]
Yazar Departmanı [1]
Antimicrobial behavior of ion-exchanged zeolite X containing fragrance

R. Tekin | N. Bac

Article | 2016 | Microporous and Mesoporous Materials234 , pp.55 - 60

Microporous zeolites are aluminosilicates composed of silicon, aluminum, and oxygen in a framework with cations. The cation contents can be exchanged with metal ions in order to add antimicrobial (antibacterial, anticandidal, and antifungal) properties. Zeolites has also recently been acquainted with fragrance applications to tailor products with controlled release properties. Here, a new application of ion exchanged zeolite X combined with adsorption properties is presented. In this study, zeolite X crystals were ion-exchanged with Zn2+ and Cu2+ ions and encapsulation of a fragrance molecule, triplal, was studied using ion-exchange . . .d zeolite X as a fragrance carrier. The antimicrobial behavior of ion-exchanged zeolite X before and after encapsulation were investigated by disc diffusion method. Zn2+ and Cu2+ loaded zeolite samples showed excellent antimicrobial activities against three bacteria Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa, a yeast Candida albicans and a fungus Aspergillus niger. Ion-exchanged zeolite X samples containing triplal sustained antimicrobial activities after the encapsulation process. © 2016 Elsevier Inc Daha fazlası Daha az

Optimization of enzyme assisted extraction of lycopene from industrial tomato waste

G. Catalkaya | D. Kahveci

Article | 2019 | Separation and Purification Technology219 , pp.55 - 63

The present study aimed to (i) select the most suitable solvent system for extraction of lycopene from industrial tomato waste; (ii) apply enzymatic pretreatment before extraction to improve lycopene recovery; and (iii) to optimize the process conditions for the selected enzyme and solvent combination using response surface methodology. Lycopene-rich oleoresins obtained through pretreatment of waste by a combination of cellulolytic and pectinolytic enzymes followed by ethyl acetate extraction had the highest phenolic compound concentration and improved antioxidant properties, as well as the highest lycopene recovery and one of the h . . .ighest red color intensity. Optimized conditions were chosen to be as follows: enzymatic reaction temperature = 40 °C, enzymatic reaction time = 5 h, enzyme:substrate ratio = 0.2 ml/g, solvent:substrate ratio = 5 ml/g, extraction time = 1 h, enzyme:enzyme ratio = 1. Oleoresin with a concentration of 11.5 mg lycopene/g was obtained at the optimum conditions. Tomato paste production waste could be valorized to produce lycopene, a valuable ingredient for food and nutraceutical industries, by combined enzymatic and solvent extraction of the waste. © 2019 Elsevier B.V Daha fazlası Daha az

Surface-enhanced Raman spectroscopy based 3D spheroid culture for drug discovery studies

Altunbek, M. | Çetin, D. | Suludere, Z. | Çulha, Mustafa

Article | 2019 | Talanta191 , pp.390 - 399

Three-dimensional (3D) spheroid cultures are more realistic tissue mimicking structures for drug discovery studies. However, analysis of 3D spheroid cultures is a challenge task because available techniques are destructive, which results with the loss of biochemical information confined in a spatial arrangement inside of spheroids. In this study, a surface-enhanced Raman scattering (SERS) based non-destructive approach is reported to study 3D cultures. Since the technique uses gold nanoparticles (AuNPs) as SERS substrates, the cells treated with AuNPs are used for the preparation of spheroids. Since SERS spectra originate from molec . . .ular species near AuNPs and their aggregates in endolysosomes, the obtained spectral information can provide significant level of information about biomolecular processes taking place in endolysosomes and dependently in cells. The performance of the approach is evaluated by monitoring the spectral changes upon external stimuli with Doxorubicin (Dox) and Paclitaxel (Pac). A layer-by-layer depth-scan SERS analysis of Dox and Pac treated spheroids reveals the spectral changes at around 555 cm-1 and 675 cm-1 originating from cholesterol and guanine, respectively, compared to control (un-treated) spheroids. Higher spectral variation is observed from the inner to the outer layers of spheroid surface. The results demonstrate that the approach can be used to monitor the intracellular responses, which are in correlation with endolysosomal pathway according to the depth-layers of intact and living 3D spheroids upon external stimuli. © 2018 Elsevier B.V Daha fazlası Daha az

Effect of temperature on the retention of Janus kinase 3 inhibitor in different mobile phase compositions using reversed-phase liquid chromatography

Yılmaz Ortak, H. | Cubuk Demiralay, E.

Article | 2019 | Journal of Pharmaceutical and Biomedical Analysis164 , pp.706 - 712

In this study, the thermodynamic dissociation constant (pK a ) values of tofacitinib in acetonitrile-water binary mixtures with of 25%, 30%, 35% and 45% (v/v) have been determined at 25–45 °C range of temperatures with reversed-phase liquid chromatography (RPLC). The chromatographic determination was achieved on a Kinetex Core-Shell EVO C18-Phenomenex (150 mm x 4.6 mm, 5 µm) analytical column. For each case pK a values and retention factors of tofacitinib by taking into account the effect of the activity coefficients in hydro-organic water–acetonitrile binary mixtures have been evaluated and which obtain by SOLVER algorithm of sprea . . .dsheet program Excel to fit experimental data to the nonlinear expression derived. From these values, the thermodynamic aqueous pK a value of the drug was calculated by different approaches. Thermodynamic parameters standard Gibbs free energy (?G°), standard enthalpy (?H°) and standard entropy (?S°) derived from dissociation constant measurements at six different temperatures were calculated by from linearity plots of IogK a against 1/T (van't Hoff plot). © 201 Daha fazlası Daha az

A cross-species and model comparison of the acute toxicity of nanoparticles used in the pigment and ink industries

Brown, D.M. | Johnston, H.J. | Gaiser, B. | Pinna, N. | Caputo, G. | Çulha, Mustafa | Fernandes, T.F.

Article | 2018 | NanoImpact11 , pp.20 - 32

A major user of nanoparticles (NPs) is the pigment and ink industry, where NPs are incorporated into numerous products (e.g. paints, food, plastics, printers, personal care products, and construction materials). Assessment of NP toxicity requires potential impacts on human health and the environment to be evaluated. In this study, we examined the toxicity of a range of NPs, of varied physico-chemical properties, used in the pigment and ink industries including silver (Ag), iron oxide (Fe2O3), titanium dioxide (TiO2), aluminium oxide (Al2O3), zinc oxide (ZnO), cobalt aluminium oxide (CoAl2O4) and cadmium selenide/zinc sulphide (CdSe/ . . .ZnS) quantum dots (QDs). Acute toxicity exerted by this NP panel to mammalian cells in vitro (macrophages, hepatocytes and alveolar epithelial cells) and aquatic environmental organisms (Raphidocelis subcapitata Daphnia magna, Lumbriculus variegatus) was investigated. For mammalian cells, cytotoxicity was assessed 24 h post exposure, at concentrations ranging from 1 to 125 µg/ml using the LDH and WST-1 assays. The aquatic toxicity of the NP panel was assessed according to OECD protocols (201, 202, 315), up to 96 h post exposure. Rats were exposed to selected NPs via intratracheal instillation (62 µg) and the pulmonary inflammatory response quantified 24 h post exposure. This cross-species comparison revealed that Ag, QDs and ZnO NPs were consistently more toxic than the other NPs tested. By looking across mammalian and aquatic ecotoxicological models we obtained a better understanding of the sensitivity of each model, and thus which models should be prioritised for selection in the future when assessing the mammalian and ecotoxicity of NPs, and in particular when screening the toxicity of a panel of NPs. We recommend that macrophage and daphnia models are prioritised when assessing the mammalian toxicity and ecotoxicity of NPs, respectively, due to their increased sensitivity, compared to the other models tested. Of interest is that the in vitro and invertebrate models used were able to predict the toxic potency of the NPs in rodents, and thus our approach has the potential to enhance the implementation of the 3Rs principles in nanotoxicology and reduce reliance on rodent testing when assessing NP safety. By identifying hazardous NPs the data obtained from this study can feed into the selection of (low toxicity) NPs to use in products and will also contribute to the safe design of future generations of NPs used by the pigment and ink industries. © 201 Daha fazlası Daha az

Betaine treatment decreased oxidative stress, inflammation, and stellate cell activation in rats with alcoholic liver fibrosis

Bingül, I. | Başaran-Küçükgergin, C. | Aydin, A. | Çoban, J. | Doğan-Ekici, I. | Doğru-Abbasoğlu, S. | Uysal, M.

Article | 2016 | Environmental Toxicology and Pharmacology45 , pp.170 - 178

The aim of this study was to investigate the effect of betaine (BET) on alcoholic liver fibrosis in rats. Fibrosis was experimentally generated with ethanol plus carbon tetrachloride (ETH + CCl4) treatment. Rats were treated with ETH (5% v/v in drinking water) for 14 weeks. CCl4 was administered intraperitoneally (i.p.) 0.2 mL/kg twice a week to rats in the last 6 weeks with/without commercial food containing BET (2% w/w). Serum hepatic damage markers, tumor necrosis factor-?, hepatic triglyceride (TG) and hydroxyproline (HYP) levels, and oxidative stress parameters were measured together with histopathologic observations. In additi . . .on, ?-smooth muscle-actin (?-SMA), transforming growth factor-ß1 (TGF-ß1) and type I collagen (COL1A1) protein expressions were assayed immunohistochemically to evaluate stellate cell (HSC) activation. mRNA expressions of matrix metalloproteinase-2 (MMP-2) and its inhibitors (TIMP-1 and TIMP-2) were also determined. BET treatment diminished TG and HYP levels; prooxidant status and fibrotic changes; ?-SMA, COL1A1 and TGF-ß protein expressions; MMP-2, TIMP-1 and TIMP-2 mRNA expressions in the liver of fibrotic rats. In conclusion, these results indicate that the antifibrotic effect of BET may be related to its suppressive effects on oxidant and inflammatory processes together with HSC activation in alcoholic liver fibrosis. © 2016 Elsevier B.V Daha fazlası Daha az

OR problems related to Home Health Care: A review of relevant routing and scheduling problems

Cissé, M. | Yalçındağ, S. | Kergosien, Y. | Şahin, E. | Lenté, C. | Matta, A.

Review | 2017 | Operations Research for Health Care13-14 , pp.1 - 22

The home health care routing and scheduling problem (HHCRSP) consists of designing a set of routes used by care workers to provide care to patients who live in the same geographic area and who must be treated at home. Hence, care activities, i.e., patient visits, must be planned to minimize measures, such as travel costs or to maximize the quality of service delivered to patients while respecting several constraints. The HHCRSP is an extension of the vehicle routing problem (VRP) with unusual side-constraints that make the issues difficult to solve. This paper details a comprehensive overview of recent OR models developed for the HH . . .CRSP, a field that has received a great amount of attention in recent years. To summarize the existing research contributions, we initially identify the most relevant features considered in the HHCRSP models, and then analyze the existing literature according to the way the different studies formulate the constraints and objective functions. We then provide an overview of methods developed to solve the HHCRSP and discuss future research directions. © 2017 Elsevier Lt Daha fazlası Daha az

Quantitative structure–activity relationship between antioxidant capacity of phenolic compounds and the plasmonic properties of silver nanoparticles

Bhutto, A.A. | Kalay, S. | Sherazi, S.T.H. | Çulha, Mustafa

Article | 2018 | Talanta189 , pp.174 - 181

Plasmonic response of silver nanoparticles (AgNPs) reduced with phenolic compounds were evaluated and correlated with the antioxidant capacities of corresponding phenolic compounds and their relative chemical structures. The reference methods including DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)) radical scavenging assays were used for the measurement of antioxidant capacity of phenolic compounds which was positively correlated with redox characteristics of these compounds against the formation of AgNPs. It is found that the higher plasmonic response of AgNPs corresponds to th . . .e highest antioxidant capacity of phenolic acids, which in turn depends on chemical structures and degree of hydroxylation. The higher degree of hydroxylation in chemical structures of phenolic compounds demonstrated the higher radical scavenging capacity and higher tendency to reduce Ag+ to AgNPs. The influence of reaction time and temperature on reducing efficiency of the tested phenolic compounds is found to be different. Some phenolic compounds such as quercetin, rutin and gallic acid reacted fast (< 1.0 min) while others were found slow reacting. This study establishes the relationship between the antioxidant capacity of phenolic acids and corresponding optical response by means of plamonics, which can be used as an innovative antioxidant detection assay for samples rich in phenolic compounds. © 201 Daha fazlası Daha az

In vitro antibacterial, antioxidant, anti-inflammatory and analgesic evaluation of Rosmarinus officinalis L. flower extract fractions

Karadağ, A.E. | Demirci, B. | Çaşkurlu, A. | Demirci, F. | Okur, M.E. | Orak, D. | Başer, K.H.C.

Article | 2019 | South African Journal of Botany125 , pp.214 - 220

Rosmarinus officinalis L. (rosemary) is a common culinary spice and herbal drug, which is used for centuries all over the world. In this present study, apolar to polar fractions of R. officinalis flowers were evaluated for their in vitro antioxidant, antibacterial, cytotoxic, anti-inflammatory and analgesic activities, respectively. Phytochemical compositions of R. officinalis extract fractions were analyzed by GC–MS and LC–MS. The antioxidant capacity of the fractions was evaluated by using the DPPH• and ABTS• methods. The antibacterial potential was determined using the in vitro broth microdilution assay against a panel of human p . . .athogens. The analgesic and anti-inflammatory activities were investigated measuring nitric oxide (NO) and prostaglandin E2 (PGE2) production in LPS-stimulated cells, respectively. In addition, in vitro cytotoxicity of the extract fractions was evaluated on RAW 264.7 murine macrophage cells by using the MTT assay. The constituents of the polar fractions were identified as rosmarinic acid, luteolin, quercetin and apigenin by LC techniques, whereas the n-hexane fraction was analyzed by GC–MS to determine the main volatile components camphor (19.6%), 1,8-cineole (11.7%), verbenone (11.5%), borneol (10.6%), ?-pinene (5.8%), and linalool (5.7%). According to the bioactivity results, the polar fraction showed the highest antioxidant activity, whereas n-hexane fraction was found to be most effective against Staphylococcus aureus (78 µg/mL). The n-hexane fraction (100 µg/mL) reduced the LPS-induced NO and PGE2 production capability. In conclusion, R. officinalis flower n-hexane and ethyl acetate fractions exhibited remarkable in vitro antibacterial, antioxidant, anti-inflammatory and analgesic activities possibly due to their polyphenol content, to the best of our knowledge for the first time. © 2019 South African Association of Botanist Daha fazlası Daha az

Electrochemically designed interfaces: Hydroxyapatite coated macro-mesoporous titania surfaces

Utku, F.S. | Seckin, E. | Goller, G. | Tamerler, C. | Urgen, M.

Conference Object | 2015 | Applied Surface Science350 , pp.62 - 68

Titanium-based implants are key weight-bearing materials in biomedical engineering due to their excellent bulk mechanical properties and biocompatibility. Designing tissue-material interfaces of titanium implants is essential for an increase in osteointegration of engineered implant materials. Surface morphology is a crucial determinant in the construction of biocompatible and osteointegrative orthopedic and dental implants. Biomimicry of the structural features of bone, specifically its macro-to-mesoporosity, may enable the bone cells to osteointegrate, attain and maintain a physiological strain level. In this study, the surface ch . . .emistry and morphology of commercially pure titanium plates were modified using electrochemistry. Titanium oxide substrates were prepared by dual acid polishing and alkaline anodization using 0.1 M KOH in an electrochemical cell with a stainless steel cathode and an anodic voltage of 40 V at 20 °C for 3 min. FE-SEM characterization revealed macro-mesoporous anodized titania surfaces, which were coated by hydroxyapatite using simulated body fluid and pulsed electrochemical deposition at 80 °C, while unprocessed commercially pure titanium surfaces were used as controls. The calcium phosphate deposit on titania plates was characterized as calcium-deficient carbonated hydroxyapatite using XRD, FTIR and FE-SEM, whereas the deposit on non-porous, non-functionalized titanium surfaces was characterized as carbonated apatite. The adhesion strength of the hydroxyapatite coated titania surfaces was 38 ± 10 MPa, implying that these surfaces may be suitable for biological and chemical functionalization of medical implants to tune bioactivity, including delivering drugs. © 2015 Elsevier B.V. All rights reserved Daha fazlası Daha az

Influence of EDC/NHS coupling chemistry on stability and cytotoxicity of ZnO nanoparticles modified with proteins

Keleştemur, S. | Altunbek, M. | Çulha, Mustafa

Article | 2017 | Applied Surface Science403 , pp.455 - 463

The toxicity of ZnO nanoparticles (NPs) is a growing concern due to its increasing use in several products including sunscreens, paints, pigments and ceramics for its antibacterial, antifungal, anti-corrosive and UV filtering properties. The toxicity of ZnO NPs is mostly attributed to the Zn 2+ release causing an increase in the intracellular reactive oxygen species (ROS) level. The surface modification with a biocompatible ligand or a polymer can be a good strategy to reduce dissolution based toxicity. In two previous studies, the conflicting results with EDC/NHS coupling chemistry for ZnO NPs were reported. In this study, the same . . . surface modification strategy with an emphasis on the stability of ZnO NPs is clarified. First, the density of –OH groups on the ZnO NPs is increased with hydrogen peroxide (H 2 O 2 ) treatment, and then a silica coating on the ZnO NPs (Si-ZnO) surface is performed. Finally, a covalent attachment of bovine serum albumin (BSA) on three different concentrations of ZnO-Si is carried out by EDC/NHS coupling chemistry. ZnO NPs have a very high dissolution rate under acidic conditions of EDC/NHS coupling chemistry as determined from the ICP-MS analysis. In addition, the amount of ZnO NPs in coupling reaction has an important effect on the dissolution rate of Zn 2+ and dependently BSA attached on the ZnO NP surfaces. Finally, the cytotoxicity of the BSA modified Si-ZnO NPs on human lung cancer (A549) and human skin fibroblast (HSF) is evaluated. Although an increased association of BSA modified ZnO NPs with cells was observed, the modification significantly decreased their cytotoxicity. This can be explained with the decreased active surface area of ZnO NPs with the surface modification. However, an increase in the mitochondrial depolarization and ROS production was observed depending on the amount of BSA coverage. © 2017 Elsevier B.V Daha fazlası Daha az

Effect of reaction mixture composition and silica source on size distribution of zeolite X crystals

Tekin, R. | Bac, N. | Warzywoda, J. | Sacco, A.

Article | 2015 | Journal of Crystal Growth411 , pp.45 - 48

Zeolite X crystals were synthesized by hydrothermal crystallization from gels with different compositions. The syntheses were performed at 95 °C using different silica sources such as sodium metasilicate anhydrous, sodium metasilicate pentahydrate, silicate solution and Cab-O-Sil. Triethanolamine was used in some syntheses in order to grow large crystals. Zeolite X crystals with diameters in the range of 1-220 µm were obtained, and Cab-O-Sil in concert with triethanolamine yielded the largest crystals. © 2014 Elsevier B.V.

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