bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Extended Method for the Practical Evaluation of the Standard Rate Constant from Cyclic Voltammetric Data
Authors: Lavagnini Irma , Antiochia Riccarda , Magno Franco 
Published: March 2004

AbstractThe Nicholson's treatment for the evaluation of the heterogeneous standard rate constant k0 of electron transfer from cyclic voltammetric (CV) data is combined with the Klingler and Kochi method suitable to totally irreversible systems in order to use very large ΔEp x n values, where n is the number of electrons involved in a simple electron‐transfer process O+n e−⇌R. An empirical relationship between the dimensionless parameter Ψ=k0 [πDnvF/(RT)]−1/2 and ΔEp x n which practically replaces the Nicholson's working curve up to about 200 mV is reported.
The Influence of Doping Levels and Surface Termination on the Electrochemistry of Polycrystalline Diamond
Authors: Latto Matthew N. , Pastor‐Moreno Gustavo , Riley D. Jason 
Published: March 2004

AbstractThe influence of surface chemistry and boron doping density on the redox chemistry of Fe(CN)$\rm{ {_{6}^{3-/4-}}}$ at CVD polycrystalline diamond electrodes is considered. It is demonstrated that for this couple both the doping density and the surface chemistry are important in determining the rate of charge transfer at the electrode/electrolyte interface. For hydrogen terminated CVD diamond metallic electrochemical behavior is always observed, even at boron doping densities as low as 7×1018 cm−3. In contrast, the electrochemical behavior of oxygen terminated CVD diamond varies with doping density, a metallic response being observed at high doping density and semiconductor behavior at low doping density. It is shown that the results attained may be explained by a surface state mediated charge transfer mechanism, thus demonstrating the importance of controlling surface chemistry in electroanalytical applications of diamond.
Electrochemical Determination of Sulfide at High Temperatures via Its Electrochemically Initiated Reaction with Diethyl‐p‐phenylenediamine in Dimethylformamide
Authors: Wildgoose Gregory G. , Giovanelli Debora , Klymenko Oleksiy V. , Lawrence Nathan S. , Jiang Li , Jones Timothy G. J. , Compton Richard G. 
Published: March 2004

AbstractThe electrochemical oxidation of DEPD proceeds via an ECrevECE mechanism in dimethylformamide. It has been investigated at elevated temperatures up to 130 °C at both micro and macro platinum and glassy carbon electrodes. Kinetic and thermodynamic parameters for the reaction process have been calculated for each temperature. Further, the voltammetric response of DEPD shows enhanced limiting currents in the presence of sulfide. The analytical utility of the approach has been investigated with linear range from 50 to 850 μM sulfide concentration observed and a corresponding limit of detection of 20 μM achievable at temperatures of 70 °C.
Voltammetry in Undiluted Acetic Acid. In Situ Determination of Water
Authors: Bak Elzbieta , Michalkiewicz Slawomir , Stojek Zbigniew 
Published: March 2004

AbstractWater present in undiluted acetic acid can be monitored in situ with Pt and Au microelectrodes using differential pulse and square‐wave voltammetries. Both reduction and oxidation peaks can be obtained. The best quantitative analytical results were obtained for the anodic peak, the Pt microelectrode, and differential pulse voltammetry. The anodic water peak is located at +1.55 V vs. the quasi reference Pt electrode. The voltammetric peak obtained at Pt electrode is apparently not a diffusional one, however, the calibration plot obtained by employing this peak is linear over a wide concentration range, up to 4 mol dm−3. The detection limit has been estimated as 2.3 mM or 0.0043 v/v%. The developed method may be particularly useful, since the Karl Fischer method can not be used to determine water in glacial acetic acid due to the estrification reaction of acetic acid with methanol. A voltammetric wave of undiluted acetic acid could not be obtained in the positive and negative ranges of potential.
Anodic Stripping Voltammetry: An AFM Study of Some Problems and Limitations
Authors: Hyde Michael E. , Banks Craig E. , Compton Richard G. 
Published: March 2004

AbstractThe use of anodic stripping voltammetry for quantitative analytical measurements using solid electrodes is addressed in the light of generic limitations arising from i) electrode heterogeneity, ii) electrode morphology, iii) inhibited electrodeposition, and iv) incomplete stripping of deposited metal in the anodic sweep. It is shown, using direct imaging of electrode surfaces via AFM and optical microscopy, that each of the preceding factors may produce significant deviations from ideal electrode behavior. The use of atomic force microscopy to fully characterize any developed ASV procedures is strongly recommended. To ensure reproducible and accurate stripping voltammetry, steps should be taken to minimize the effects discussed.
Detecting DNA Damage with a Silver Solid Amalgam Electrode
Authors: Kuchariková Katerina , Novotny Ladislav , Yosypchuk Bogdan , Fojta Miroslav 
Published: March 2004

AbstractMercury electrodes modified with supercoiled (sc) DNA have been used as highly sensitive tools for the detection of DNA strand breaks or as sensors for DNA cleaving substances. In this paper we show that silver solid amalgam electrode (AgSAE), in connection with alternating current voltammetry, provides similar information about DNA damage as the hanging mercury drop electrode. The AgSAE can be used for the detection of enzymatic or chemical DNA cleavage in solution or at the electrode surface. AgSAE modified with scDNA can be utilized as a sensor for DNA nicking substances.
Hydrogen Peroxide Detection at Electrochemically and Sol‐Gel Derived Ir Oxide Films
Authors: Elzanowska Hanna , Abu‐Irhayem Erfan , Skrzynecka Beata , Birss Viola I. 
Published: March 2004

AbstractIr oxide (IrOx) films, formed electrochemically on bulk Ir metal (Ir/IrOx) and also on sol‐gel (SG) derived non‐silica based nanoparticulate Ir, have been studied as material useful for the detection of hydrogen peroxide, with possible application as a glucose biosensor. H2O2 reduction and oxidation on Ir/IrOx and SG‐derived IrOx films, deposited on various substrates such as Pt, Ir and GC, have been compared to the H2O2 behavior at the bare substrate. It was found that H2O2 reduction proceeds on the underlying electrode substrate, while H2O2 oxidation is independent of the nature of the substrate, therefore occurring via the IrOx film. The reactivity of IrOx towards H2O2 oxidation is similar to that seen at Pt, although IrOx has the additional advantages of excellent stability, insensitivity to common interfering substances, biocompatibility and a linear range of detection, up to at least 12 mM H2O2. At micromolar concentrations of H2O2, a second mode of detection, involving the catalyzed growth of IrOx films at Ir substrates, can be employed. These two methods of H2O2 analysis (oxidation/reduction and enhanced IrOx growth) can also be employed for glucose detection using IrOx‐based glucose biosensors.
Novel Cesium‐Selective Electrodes Based on Lipophilic 1,3‐Bisbridged Cofacial‐calix[6]crowns
Authors: Jeon Seungwon , Yeo Heekyoung , Lee Hyo Kyoung , Ko Seung Whan , Nam Kye Chun 
Published: March 2004

AbstractFive bisbridged calix[6]crowns have been investigated as Cs+ionophore in PVC membrane electrodes. As ionophores, three 1,3‐bisbridged calix[6]crown‐4‐ethers(I–III), 1,3‐bisbridged calix[6]crown‐5‐ether(IV), and 1,3‐bisbridged calix[6]crown‐6‐ether(V) have been evaluated. The membranes all give good Nernstian response in the concentration range from 1×10−7to 1×10−1 M of cesium ion. The best detection limits (−loga=7.08–7.36) are obtained for electrode membranes containing 1,3‐bisbridged cofacial‐calix[6]crown‐4‐ethers(I‐III), and the values are the lowest compared with those reported previously. The highest selectivity coefficients [$\rm{ {\rm p}K_{{\rm Cs}^ + ,{\rm j}}^{{\rm pot}} = 5.53({\rm Cs/Na}),}$3.74(Cs/K), 2.63(Cs/Rb)] are obtained for the membrane of 1,3‐bisbridged calix[6]crown‐4‐ether(II), and these values are also the highest compared with previous reports for Cs+‐ISEs. The highest selectivity towards cesium ion is attributed to the geometrically cofacial positions of two crown‐ethers in calix[6]crowns in order to provide the complex of cesium ion and eight oxygens of cofacial crowns.
Chemical composition of essential oil of Cinnamomum tamala Nees et Eberm. leaves
Authors: Mir Showkat R. , Ali Mohammed , Kapoor Reni 
Published: March 2004

AbstractA hydrodistilled oil obtained from the leaves of Cinnamomum tamala Nees et Eberm., grown in India, was analysed by capillary GC and GC–MS. The leaf volatile oil contained 40 constituents, of which a high proportion were monoterpenes (65.6%). The predominant monoterpenes were trans‐sabinene hydrate (29.8%), (Z)‐β‐ocimene (17.9%), myrcene (4.6%), α‐pinene (3.1%) and β‐sabinene (2.3%). Among 21 sesquiterpenes (32.9%), the major ones were germacrene A (11.3%) and α‐gurjunene (4.7%). Copyright © 2004 John Wiley & Sons, Ltd.
Composition and antibacterial activity of the essential oil of six Stachys species from Serbia
Authors: Grujic‐Jovanovic Slavica , Skaltsa Helen D. , Marin Petar , Sokovic Marina 
Published: March 2004

AbstractThe essential oils of Stachys scardica, S. ofﬁcinalis, S. germanica, S. sylvatica, S. plumosa and S. recta were analysed by GC–MS. From more than 100 identiﬁed constituents of the oils, the sequiterpene hydrocarbons were the major components of all samples except that of S. plumosa, which was rich in monoterpene hydrocarbons. Furthermore, the oils were tested against three Gram‐positive and three Gram‐negative bacteria. The essential oil of S. ofﬁcinalis proved to be the most active. Copyright © 2004 John Wiley & Sons, Ltd.
Essential oil constituents of aerial parts of Artemisia scoparia Waldst. & Kit.
Authors: Kapoor Reni , Ali Mohammed , Mir Showkat R. , Raﬁullah M. R. M. 
Published: March 2004

AbstractHydrodistilled oil obtained from the aerial parts of Artemisia scoparia Waldst. & Kit. was analysed by capillary GC and GC–MS. The volatile oil of the 10–15 cm high herb was composed mainly of eight monoterpenes (ca. 68.5%), and the predominant constituents were β‐myrcene (24.4%), γ‐terpinene (18.3%), neral (12.5%) and cis‐p‐mentha‐2‐en‐1‐ol (5.1%). Among seven sesquiterpenes (6.9%) present in the oil, the prominent one was β‐caryophyllene (3.4%). p‐Cymene (17.4%) and p‐cymene‐8‐ol were the characterized aromatic compounds in the volatile oil. Three aliphatic constituents, identiﬁed as n‐octane, n‐heptadecane and n‐eicosane, occurred in trace amounts. Copyright © 2004 John Wiley & Sons, Ltd.
Olfactory study on optically active citronellyl derivatives
Authors: Yamamoto Takeshi , Shimada Akemi , Ohmoto Tatsuya , Matsuda Hiroyuki , Ogura Miharu , Kanisawa Tsuneyoshi 
Published: March 2004

AbstractOdour threshold concentrations, determined in agueous‐ethanol solution, and odour qualities are reported for 18 enantiomeric and diastereomeric pairs of citronellyl derivatives [13 linear monoterpene compounds and ﬁve monocyclic α‐damascone and α‐ionone‐related compounds (trans‐2,2,6‐trimethylcyclohexyl derivatives)] (98%ee). Fairly large differences in both odour strength and odour qualities were found between the monocyclic diastereomeric pairs. In four of the ﬁve cyclic compounds, the (1R, 6S)‐form was found to be stronger and more sensorily active than the antipode. On the other hand, the linear enantiomeric pairs showed only small differences in both odour strength (half of them showed the same threshold values) and odour character. However, all the (3S)‐forms showed milder, cleaner and a much preferable top note than the (3R)‐forms except for citronellyl nitrile and the diester (citronellyl ethyl oxalate), whose (3R)‐form showed a characteristic ﬂoral musk odour, although the (3S)‐form showed a rose ﬂoral odour. Copyright © 2004 John Wiley & Sons, Ltd.
Composition of the essential oil from ﬂowerheads of Chrysanthemum coronarium L. (Asteraceae) growing wild in Southern Italy
Authors: Senatore Felice , Rigano Daniela , De Fusco Raffaele , Bruno Maurizio 
Published: March 2004

AbstractThe essential oils from the aerial parts of Chrysanthemum coronarium L. (Asteraceae) growing wild in two different localities of Southern Italy, Lascari (L) and Palinuro (P), were obtained by hydrodistillation in a 0.13–0.16% yield. The oils were analysed by GC and GC–MS; 68 constituents, amounting to 89.0% of the oil (L), and 43 constituents, amounting to 91.6% of the oil (P), were identiﬁed. The trans‐spiroketal–enol ether 2‐(2,4‐hexadiynylidene)‐1,6‐dioxaspiro[4,4]non‐3‐ene (trans‐tonghaosu) with chrysanthenyl and lyratyl esters and camphor were the main components of the oils. Copyright © 2004 John Wiley & Sons, Ltd.
Essential oil composition of Cephalophora aromatica cultivated in Iran
Authors: Seﬁdkon F. , Omidbaigi R. 
Published: March 2004

AbstractHydrodistilled volatile oil from the ﬂowers of Cephalophora aromatica Schrad. (cultivated in Iran) was analysed by a combination of GC and GC–MS. Twenty‐nine components were identiﬁed. The main constituents of the essential oil were 2‐ethyl hexanoic acid (27.0%), n‐undecane (14.1%), decane (11.4%) and geranyl tiglate (7.9%). Copyright © 2004 John Wiley & Sons, Ltd.
Analysis of the volatile constituents of Nepeta macrosiphon Boiss. grown in Iran
Authors: Javidnia K. , Miri R. , Jafari A. , Rezai H. 
Published: March 2004

AbstractComposition of the volatile oil of Nepeta macrosiphon Boiss. (Lamiaceae) was investigated by GLC and GC–MS. Seventy‐three components, representing 96.9% of the total oil, were characterized. The main components of the oil were spathulenol (28.8%), α‐cadinol (13.6%), bicyclogermacrene (10.1%), β‐caryophyllene (9.6%) and linalool (5.6%). Nepetalactone isomers were not present in the essential oil of N. macrosiphon. Copyright © 2004 John Wiley & Sons, Ltd.
Essential oils and fragrance compounds: bioactivity and mechanisms of action
Authors: Lahlou Mouhssen 
Published: March 2004

AbstractMany studies on essential oils and fragrance compounds are performed and then published without any biological testing whatsoever. In addition, the mechanisms of action of such compounds can remain unknown for years in many cases. The present paper gives more comprehensive knowledge on the actions of essential oils and fragrance compounds; in addition, the bioactivity of chiral, isomer and chemotype compounds is discussed. Copyright © 2004 John Wiley & Sons, Ltd.
Volatile constituents of different organs of Psoralea bituminosa L.
Authors: Bertoli Alessandra , Menichini Francesco , Noccioli Cecilia , Morelli Ivano , Pistelli Luisa 
Published: March 2004

AbstractThe essential oil and SPME samples of the leaves, ﬂowers and seeds of Psoralea bituminosa L. were analysed by GC and GC–MS. We have investigated also the presence of monoterpene or aliphatic alcohol glucosides. The essential oils showed both qualitative and quantitative differences. The main constituents of the leaf and the ﬂower essential oils were caryophyllene (23% and 18%, respectively), β‐farnesene (15% and 6%, respectively), and germacrene D (24% and 18%, respectively). Signiﬁcant amounts (7%) of the same compounds were also directed in the seed essential oil, but tricyclene (11%) and α‐pinene (50%) were the most important constituents of this oil. The volatile fractions of remaining leaf aqueous extracts after treatment with β‐glucosidase revealed qualitative differences in comparison with the composition of the corresponding essential oils, and high levels of 3‐hexen‐1‐ol (37%) and 1‐octen‐3‐ol (27%) were observed. The SPME analysis of the fresh leaves, ﬂowers and seeds of P. bituminosa conﬁrmed the qualitative composition of the volatile oils, even if we detected signiﬁcative differences in the percentage ratio between monoterpenes and sesquiterpenes in comparison with the oils, where sesquiterpenes were the main components. In fact the variation of the monoterpenes, tricyclene, α‐pinene and camphene between the leaf oil and the corresponding headspace sample was remarkable: tricyclene increased from 0.1% to 8%, α‐pinene from 0.1% to 16% and camphene from 0.3% to 10% in the SPME samples. Copyright © 2004 John Wiley & Sons, Ltd.
Coffee ﬂavour: an overview
Authors: Buffo Roberto A. , Cardelli‐Freire Claudio 
Published: March 2004

AbstractThis paper is a concise review of the research on coffee ﬂavour to serve as a rapid reference on the subject. It covers the process of roasting coffee beans, the volatile and non‐volatile components generated by the process and the chemical reactions responsible for their formation. Volatile compounds signiﬁcant on the determination of coffee aroma are given according to the most recent research. Finally, the paper discusses the chemical indexes used over the years to characterize coffee ﬂavour deterioration and estimation of shelf‐life. Copyright © 2004 John Wiley & Sons, Ltd.
Quantitation of suspected allergens in fragrances (Part I): evaluation of comprehensive two‐dimensional gas chromatography for quality control
Authors: Shellie Robert , Marriott Philip , Chaintreau Alain 
Published: March 2004

AbstractAn evaluation of comprehensive two‐dimensional (2D) gas chromatography (GC×GC) was performed to assess its suitability for the analysis of volatile fragrance components, recognized by the European Commission's Scientiﬁc Committee on Cosmetics and other Non‐food Products (SCCNFP) as possible skin sensitizers. The 24 volatile components listed by the SCCNFP were baseline‐resolved or better within one 30 min analysis. High‐quality calibration data for standard mixtures were obtained, with R2 > 0.998 over the concentration range 2–1000 mg/l. However, the analysis of small spiked amounts of target compounds in truly complex fragrances was problematic, due to uncertainty in component assignment. The beneﬁts and limitations of GC×GC are reported, and a discussion of the proposed directions for the solution of this analysis is provided. Copyright © 2004 John Wiley & Sons, Ltd.
Fragrance materials and their environmental impact
Authors: Salvito Daniel T. , Vey Matthias G. H. , Senna Ronald J. 
Published: March 2004

AbstractA brief discussion on the environmental fate and effects of fragrance materials was recently presented in Cadby et al.1. This paper has been prepared as a more detailed discussion of the environmental effects associated with fragrance materials. Cadby et al.1 presented a detailed discussion of the rigorous science employed to protect the consumer and the environment from adverse effects from these materials. The Research Institute for Fragrance Materials (RIFM) has established a comprehensive environmental research and testing programme to determine the potential environmental risks posed by fragrance materials to the environment. Sponsored research and testing includes ecotoxicological studies, the biotransformation of fragrance materials in wastewater treatment, and their fate in the terrestrial environment. RIFM has published a conservative screening level risk assessment model following established environmental risk assessment paradigms (i.e. the predicted environmental concentration: predicted no effect concentration quotient; the PEC–PNEC ratio).2 In an initial screening of all discrete fragrance materials, using only volume of use and available physical‐chemical parameters, 92% of these materials are shown to pose an acceptable environmental risk, i.e. their PEC–PNEC ratio is less than 1. Copyright © 2004 John Wiley & Sons, Ltd.
Streamwater quality as affected by wild fires in natural and manmade vegetation in Malaysian Borneo
Authors: Malmer Anders 
Published: March 2004

AbstractIn 1998 a wild fire struck a paired catchment research area under long‐term monitoring of hydrological and nutrient budgets. Streamwater quality as concentrations of dissolved and suspended particulate matter was monitored during 1·5–2·5 years after the fire in streams from seven different catchments. As the catchments, due to earlier experimental treatments, had different vegetations, varying effects related to different fire intensities were observed.The highest, mean stormflow, suspended sediment concentrations resulted from intensive fire in secondary vegetation that had experienced severe soil disturbance in previous treatments (crawler tractor timber extraction 10 years earlier). Stormflow concentrations were typically still about 400 mg l−1 in 1999 (10–21 months after the fire), which was about the maximum recorded concentration in streams during initial soil disturbance in 1988. Forest fire in natural forest resulted in less than half as high stormflow concentrations.For dissolved elements in streamwater there was a positive relation between fuel load (and fire intensity) and concentration and longevity of effects. Stream baseflow dissolved nutrient concentrations were high in the months following the fire. Mean baseflow K concentrations were 8–15 mg l−1 in streams draining catchments with intensive fire in secondary vegetation with large amounts of fuel. After controlled fire for forest plantation establishment in 1988 corresponding concentrations were 3–5 mg l−1, and after forest fire in natural forest in this study about 2 mg l−1.This study shows differences in response from controlled fire for land management, forest fire in natural forests and wild fires in manmade vegetations. These differences relate to resistance and resilience to fire for the involved ecosystems. There is reason to believe that wild fires and repeated wild fires during or after droughts, in successions caused by human influence, may lead to larger losses of ecosystem nutrient capital from sites compared with forest fires in natural forests. As fire in the humid tropics becomes more common, in an increasingly spatially fragmented landscape, it will be important to be aware of these differences. Copyright © 2004 John Wiley & Sons, Ltd.
The effect of drawdown on suspended solids and phosphorus export from Columbia Lake, Waterloo, Canada
Authors: Shantz Mike , Dowsett Elizabeth , Canham Emma , Tavernier Guillaume , Stone Mike , Price Jonathan 
Published: March 2004

AbstractThis study examines the effect of drawdown on the timing and magnitude of suspended solids and associated phosphorus export from a 12 ha reservoir located in an urbanized watershed in southern Ontario, Canada. Water level in Columbia Lake was lowered by 1·15 m over a 2‐week period in November 2001. The total phosphorus (TP) concentrations ranged from 63 to 486 µg L−1 in Columbia Lake and 71 to 373 µg L−1 at its outflow. All samples exceeded the Provincial Water Quality Objective of 30 µg TP L−1. Outflow concentrations of suspended solids and TP increased significantly with decreasing lake level and were attributed to the resuspension of cohesive bottom sediments that occurred at a critical threshold lake level (0·65 m below summer level). Suspended solids at the outflow consisted of flocculated cohesive materials with a median diameter (D50) of c. 5 µm. Particulate organic carbon accounted for 8·5% of the suspended solids export by mass. A total mass of 18·5 t of suspended solids and 62·6 kg TP was exported from Columbia Lake, which represents a significant pulse of sediment‐associated P to downstream environments each autumn during drawdown. The downstream impacts of this release can be minimized if the water level in Columbia Lake is lowered no more than 0·5 m below summer levels. Copyright © 2004 John Wiley & Sons, Ltd.