Electrochemical tuning of capacitive response of graphene oxide

Increasing energy demands of modern society requires deep understanding of the properties of energy storage materials as well as their performance tuning. We show that the capacitance of graphene oxide (GO) can be precisely tuned using a simple electrochemical reduction route. In situ resistance measurements, combined with cyclic voltammetry measurement and Raman spectroscopy, have shown that upon the reduction GO is irreversibly deoxygenated which is further accompanied with structural ordering and increasing of electrical conductivity. The capacitance is maximized when the concentration of oxygen functional groups is properly balanced with the conductivity. Any further reduction and de-oxygenation leads to the gradual loss of the capacitance. The observed trend is independent on the preparation route and on the exact chemical and structural properties of GO. It is proposed that an improvement of capacitive properties of any GO can be achieved by optimization of its reduction conditions.Comment: 23 pages, 7 figures, 59 reference

Electrochemical tuning of capacitive response of graphene oxide

The increasing energy demands of modern society require a deep understanding of the properties of energy storage materials, as well as the tuning of their performance. We show that the capacitance of graphene oxide (GO) can be precisely tuned using a simple electrochemical reduction route. In situ resistance measurements, in combination with cyclic voltammetry measurements and Raman spectroscopy, have shown that upon reduction GO is irreversibly deoxygenated, which is further accompanied by structural ordering and an increase in electrical conductivity. The capacitance is maximized when the concentration of oxygen functional groups is properly balanced with the conductivity. Any further reduction and deoxygenation leads to a gradual loss of capacitance. The observed trend is independent of the preparation route and the exact chemical and structural properties of GO. It is proposed that an improvement in the capacitive properties of any GO can be achieved by optimization of its reduction conditions.This is the peer-reviewed version of the following article: Gutić, Sanjin J., Dževad Kozlica, Fehim Korać, Danica Bajuk-Bogdanović, Miodrag Mitrić, Vladimir M. Mirsky, Slavko V. Mentus, and Igor A. Pašti. "Electrochemical tuning of capacitive response of graphene oxide." (2018). [https://doi.org/10.1039/C8CP03631D]Published version available at: [http://vinar.vin.bg.ac.rs/handle/123456789/7877

Gratitude and hospitality: Tamil refugee employment in London and the conditional nature of integration

Healy, R. L. 2014. The definitive, peer-reviewed and edited version of this article is published in Environment and Planning A, 2014, 46(3), pp. 614-628, http:dx/doi.org/10.1068/a4655The policy of integration attempts to address different elements of exclusion, yet relatively little research has considered what integration means to the refugees themselves. This paper explores one key area for supporting integration: employment.ESRC PTA-030-2005-0082

Simulacija rada visoke peći prilikom supstitucije koksa i sprašenog uglja granulisanom otpadnom plastikom

The possibility of using the waste plastic as reducing agent in blast furnace for obtaining pig iron is in focus for the past couple year. The simulation of blast furnace process in BFC software has been performed in order to analyze the coke and coals saving, CO2 emission and determining the economic benefits. Three different batches were made for comparative analysis, depending on the batch composition and input of batch components into the blast furnace: case 1 (C1), case 2 (C2) and case 3 (C3). The base case, C1 contains sinter (bulk material) which is needed for obtaining 1 tone of pig iron, quartz which provides slag alkalinity and coke as reducing and energy agent. C2 has the same components as C1, but contains pulverized coal instead one part of coke and C3 contains granulated waste plastic instead coke in an approximately the same amount as pulverized coal. The substitution of coke with pulverized coal and waste plastic is 18.6 % and 25.2 %, respectively. The economic, productivity and ecologic aspects have been analyzed. The consumption of each tone of waste plastic in blast furnace saves 360 $, which is 18 times more than its price, bearing in mind that the market price of coke is 380$/t % and waste plastic 20 $/t. Regarding the specific productivity, it decreases from 2.13 for C1 to 1.87 for C3. From an environmental aspect there are two main benefits: reduction of CO2 emission and impossibility of dioxin formation. The CO2 emission was 20.18, 19.46 and 17.21 for C1, C2 and C3, respectively.Mogućnost upotrebe otpadne plastike kao reducenta u visokoj peći je u fokusu interesovanja poslednjih godina. U cilju analize uštede koksa i uglja, smanjenja emisije CO2 i utvrđivanja ekonomskih benefita urađena je simulacija visokopećnog procesa u BFC programskom paketu. Radi uporedne analize simulirana su tri slučaja u zavisnosti od sastava šarže i načina unošenja komponenti šarže u visoku peć: sučaj 1 (S1), slučaj 2 (S2) i slučaj 3 (S3). Šarža u baznom slučaju, S1, se sastoji od sintera, tj. zasipa koji je potreban da se dobije 1 t gvožđa, topitelja koji obezbeđuje bazicitet troske i koksa kao reducenta i energenta. Šarža u slučaju S2, pored komponenata koje sadrži šarža u slučaju S1, sadrži sprašeni ugalj umesto jednog dela koksa, a šarža u slučaju S3 umesto koksa sadrži granulisanu otpadnu plastiku u približno istoj količini kao sprašeni ugalj. Supstitucija koksa sprašenim ugljem i otpadnom plastikom je 18,6$, što je 18 puta više od njene cene imajući u vidu da je tržišna cena koksa 380 $/t, a otpadne plastike 20$/t. Što se tiče specifične proizvodnosti, ista opada od 2,13 za S1 do 1,87 za S3. Sa ekološkog aspekta postoje dva glavna benefita: smanjenje emisije CO2 i nemogućnost formiranja dioksina. Emisija CO2 je bila 20,18; 19,46 i 17,21 % za S1, S2 i S3, respektivno

Unlocking cancer glycomes from histopathological formalin-fixed and paraffin-embedded (FFPE) tissue microdissections

N- and O-glycans are attractive clinical biomarkers as glycosylation changes in response to diseases. The limited availability of defined clinical specimens impedes glyco-biomarker identification and validation in large patient cohorts. Formalin-fixed paraffin-embedded (FFPE) clinical specimens are the common form of sample preservation in clinical pathology, but qualitative and quantitative N- and O-glycomics of such samples has not been feasible to date. Here, we report a highly sensitive and glycan isomer selective method for simultaneous N- and O-glycomics from histopathological slides. As few as 2,000 cells isolated from FFPE tissue sections by laser capture microdissection were sufficient for in-depth histopathology-glycomics using porous graphitized carbon nanoLC ESI-MS/MS. N- and O-glycan profiles were similar between unstained and hematoxylin and eosin stained FFPE samples but differed slightly compared to fresh tissue. This method provides the key to unlock glyco-biomarker information from FFPE histopathological tissues archived in pathology laboratories worldwide

Age of Mammuthus trogontherii from Kostolac, Serbia, and the entry of megaherbivores into Europe during the Late Matuyama climate revolution

At the Drmno open-pit coal mine near Kostolac in Serbia, a nearly complete skeleton of Mammuthus trogontherii (nicknamed Vika) was discovered in a fluvial deposit overlain by a loess-paleosol sequence where a second paleontological level named Nosak with remains of M. trogontherii was found. We studied the magnetostratigraphy of the Kostolac sedimentary sequence and found that the Vika layer dates to similar to 0.8 Ma, shortly before the Brunhes-Matuyama boundary. In addition, according to our age model and previously reported optically stimulated luminescence and electron spin resonance dates, the Nosak fossils have an estimated age of 0.19 Ma and lived during the earliest part of Marine Isotope Stage 6. It appears therefore that at Kostolac, M. trogontherii is preserved both at its earliest occurrence at similar to 0.8 Ma and close to its latest occurrence at 0.19 Ma, and may well have been present in between, albeit not yet found. We speculate that megaherbivores such as M. trogontherii entered Europe along a conjunct Danube-Po River migration conduit connecting western Asia-Levant with central-southern Europe where vast and exploitable ecosystems, particularly suited for steppe- or savanna-adapted megaherbivores from Asia and Africa, developed during the late early Pleistocene climate revolution at around 0.8 Ma

Quantitative determination of secoiridoid and xanthone glycosides of Gentiana dinarica Beck cultured in vitro

Gentiana dinarica Beck, native to the Balkan Dinaric Mountains, was established in vitro from axillary shoot buds. It was maintained in the form of shoot cultures on MS medium supplemented with 1.0 mg l(-1) 6-benzyladenine (BA) and 0.1 mg l(-1) alpha-naphthaleneacetic acid and excised root cultures were maintained on 1/2MS medium with 0.5 mg l(-1) indole-3-butyric acid (IBA). Shoot cultures, adventitious roots and excised root cultures were analysed by HPLC techniques for the presence of secoiridoids and xanthones. Gentiopicrin and swertiamarin, the dominant components of shoot cultures, could not be detected in root cultures. Xanthones were present in both shoot and root cultures with norswertianin-1-O-primeveroside as the dominant metabolite. The secoiridoid and xanthone content, although characteristic for certain plant organs, was dependent on the concentration of plant growth regulators (BA and IBA) added to the medium. BA in the shoot multiplication stage strongly increased the secondary metabolite (SEM) content of shoot cultures. IBA had little effect on SEM accumulation in shoots during rooting, while it moderately stimulated SEM accumulation in excised root cultures.Serbian Ministry of Education and Science [173015

Quantitative determination of secoiridoid and xanthone glycosides of Gentiana dinarica Beck cultured in vitro

Gentiana dinarica Beck, native to the Balkan Dinaric Mountains, was established in vitro from axillary shoot buds. It was maintained in the form of shoot cultures on MS medium supplemented with 1.0 mg l(-1) 6-benzyladenine (BA) and 0.1 mg l(-1) alpha-naphthaleneacetic acid and excised root cultures were maintained on 1/2MS medium with 0.5 mg l(-1) indole-3-butyric acid (IBA). Shoot cultures, adventitious roots and excised root cultures were analysed by HPLC techniques for the presence of secoiridoids and xanthones. Gentiopicrin and swertiamarin, the dominant components of shoot cultures, could not be detected in root cultures. Xanthones were present in both shoot and root cultures with norswertianin-1-O-primeveroside as the dominant metabolite. The secoiridoid and xanthone content, although characteristic for certain plant organs, was dependent on the concentration of plant growth regulators (BA and IBA) added to the medium. BA in the shoot multiplication stage strongly increased the secondary metabolite (SEM) content of shoot cultures. IBA had little effect on SEM accumulation in shoots during rooting, while it moderately stimulated SEM accumulation in excised root cultures.Serbian Ministry of Education and Science [173015