bluuebunny/crossref_metadata_2025_split huggingface dataset:
Selection of two reliable parameters to evaluate the impact of the mobile‐phase composition on capillary electrochromatography performance with monolithic and particle‐packed capillary columns
Authors: Progent Frédéric , Augustin Violaine , Tran N. Thuy , Descroix Stéphanie , Taverna Myriam 
Published: February 2006

AbstractDifferent models have been described in the literature to evaluate the total porosity of CEC columns: gravimetric, flow as well as conductivity‐based methods. In this study, these models have been compared for two kinds of CEC columns: two mixed‐mode silica particle stationary phases and different monolithic columns (acrylate or polystyrene divinylbenzene‐based). The total porosities measured from the conductivity‐based methods were lower than the total column porosities obtained by gravimetric or flow methods for all the investigated columns while the wide distribution of observed values shows that conductivity‐based methods discriminate columns more efficiently with very different properties. We propose a conductivity‐based method taking into account the actual length proposed by Horvath, to evaluate what we call an ”actual electrokinetic” porosity (AEP). This parameter, based on electrokinetic theory only, affords the most consistent evaluation of porosity under experimental CEC conditions for the packed‐ and acrylate‐based monolithic columns. To illustrate the potential of AEP and actual EOF for the estimation of the performances of a CEC system (stationary and mobile phases) we studied the influence of the mobile‐phase composition on these parameters for CEC separations with an ammonium embedded packed stationary phase. The AEP and the actual electroosmotic mobility should allow a better understanding of the perfusive EOF and stationary‐phase wettability. For neutral compounds (substituted phenols), AEP evaluation allowed us to predict the mobile‐phase conditions able to enhance the efficiency while both AEP and actual EOF had to be considered in the case of peptide analysis.
Enantiomeric screening of racemic citalopram and metabolites in human urine by entangled polymer solution capillary electrophoresis: An innovatory robustness/ruggedness study
Authors: Berzas‐Nevado Juan José , Villaseñor‐LLerena María Jesús , Guiberteau‐Cabanillas Carmen , Rodríguez‐Robledo Virginia 
Published: February 2006

AbstractSeveral CE methods have been developed to achieve the chiral separation of citalopram (CIT) and its metabolites demethylcitalopram (DCIT), didemethylcitalopram (DDCIT), and citalopram N‐oxide (CIT‐NO). All of these compounds were present as racemic mixtures. The best method, which led to the first ever chiral screening of CIT, DCIT, DDCIT, and CIT‐NO, involved the use of carboxymethyl‐γ‐CD (CM‐γ‐CD) and the entangled polymer hydroxypropylmethylcellulose (HPMC) as chiral and selectivity additives, respectively, in the buffer system. In an effort to improve the selectivity and sensitivity of the method, the chemical and instrumental parameters were optimized. The best conditions were short‐end anodic hydrodynamic injection (6 s, 0.7 psi); as BGE pH 5, 20 mM phosphate buffer, 0.2% w/v CM‐γ‐CD, 0.05% w/v HPMC; voltage of 28 kV with a ramp applied (0.4 s); cartridge temperature of 20°C; detection at 205 nm. In addition, a simple and rapid achiral CE method for the determination of citalopram propionic acid (CIT‐PA, the only anionic metabolite of CIT) is also reported for the first time. Prior to the electrophoretic procedure it was necessary to apply an extraction and preconcentration step to obtain analytes from the human urine samples. This was achieved using an optimized SPE process. Moreover, an innovatory experimental and statistical design approach, which involves the simultaneous evaluation of the global robustness and ruggedness effects, was applied. Both of the proposed methods proved to be very useful in the chiral pharmacokinetic screening of CIT and related metabolites in clinical human urine samples.
Micellar electrokinetic chromatography and capillary electrochromatography of nitroaromatic explosives in seawater
Authors: Giordano Braden C. , Copper Christine L. , Collins Greg E. 
Published: February 2006

AbstractThe ability to separate nitroaromatic and nitramine explosives in seawater sample matrices is demonstrated using both MEKC and CEC. While several capillary‐based separations exist for explosives, none address direct sampling from seawater, a sample matrix of particular interest in the detection of undersea mines. Direct comparisons are made between MEKC and CEC in terms of sensitivity and separation efficiency for the analysis of 14 explosives and explosive degradation products in seawater and diluted seawater. The use of high‐salt stacking with MEKC results, on average, in a three‐fold increase in the number of theoretical plates, and nearly double resolution for samples prepared in 25% seawater. By taking advantage of long injection times in conjunction with stacking, detection limits down to sub mg/L levels are attainable; however, resolution is sacrificed. CEC of explosive mixtures using sol‐gels prepared from methyltrimethoxysilane does not perform as well as MEKC in terms of resolving power, but does permit extended injection times for concentrating analyte onto the head of the separation column with little or no subsequent loss in resolution. Electrokinetic injections of 8 min at high voltage allow for detection limits of explosives below 100 µg/L.
Rapid separation and determination of carbamate insecticides using isocratic elution pressurized capillary electrochromatography
Authors: Wu Xiaoping , Wang Ling , Xie Zenghong , Lu Jieshan , Yan Chao , Yang Pengyuan , Chen Guonan 
Published: February 2006

AbstractAn isocratic elution pressurized CEC (pCEC) system was used to separate and determine ten carbamate insecticides. It was found that introduction of the electrical field, supplementary pressure, and SDS in the proposed method greatly improved the speed, column efficiency, selectivity, and repeatability for separation and determination of carbamates. On a capillary column of 75 µm ID packed with 3 µm octadecyl silica, baseline separation and detection of ten analytes was performed by using a mobile phase consisting of 30% v/v ACN and 70% v/v of 5 mmol/L ammonium acetate (pH 6.5) containing 1 mmol/L SDS and 0.01% triethylamine (TEA). Under the optimum conditions ten carbamate insecticides could be completely separated within 20 min. For the real vegetable samples, an SPE procedure for the cleanup of matrices was carried out prior to pCEC analysis. The detection limits of 0.05–1.6 mg/kg for ten carbamates and mean recoveries of 51.3–109.2% for eight kinds of vegetable samples at different concentrations of carbamates with RSD less than 11.4% were obtained, respectively. The proposed method has been proved to be effective in the rapid analysis of carbamate residues in vegetables.
Capillary zone electrophoretic chiral discrimination using 6‐O‐(2‐hydroxy‐3‐trimethylammoniopropyl)‐β‐cyclodextrin as a chiral selector
Authors: Lin Xiuli , Zhao Minggang , Qi Xinyu , Zhu Chenfu , Hao Aiyou 
Published: February 2006

AbstractA charged highly water‐soluble CD derivative, 6‐O‐(2‐hydroxy‐3‐trimethylammoniopropyl)‐β‐CD (herein noted as 6‐HPTMA‐β‐CD) was synthesized and successfully used as a chiral selector for enantiomeric separation of some acidic compounds by CZE in an uncoated capillary. Substitution with 2‐hydroxy‐3‐trimethylammoniopropyl groups at the primary hydroxyl group of the CD was aimed at influencing the magnitude and selectivity of analyte–CD interactions. The behavior of 6‐HPTMA‐β‐CD was compared with that of the commercially available quaternary ammonium‐β‐CD (QA‐β‐CD) under the same separating conditions. The experiments were carried out using a BGE consisting of 50 mM phosphate in the pH range of 4–6 by adding a relatively low concentration of chiral selector (less than 10 mM). The effects of the concentration of CD and the pH of the electrolyte on the resolution of these compounds were studied.
Using Rock‐Eval 6 pyrolysis for tracking fossil organic carbon in modern environments: implications for the roles of erosion and weathering
Authors: Copard Yoann , Di‐Giovanni Christian , Martaud Thomas , Albéric Patrick , Olivier Jean‐Emmanuel 
Published: February 2006

AbstractThis work relates to the debate on the fossil organic carbon (FOC) input in modern environments and its possible implication for the carbon cycle, and suggests the use of Rock‐Eval 6 pyrolysis as a relevant tool for tracking FOC in such environments. Considering that such a delivery is mainly due to supergene processes affecting the continental surface, we studied organic matter in different reservoirs such as bedrocks, alterites, soils and rivers in two experimental catchments at Draix (Alpes de Haute Provence, France). Samples were subjected to geochemical (Rock‐Eval 6 pyrolysis) investigations and artificial bacterial degradations. After comparing the geochemical fingerprint of samples, geochemical markers of FOC were defined and tracked in the different reservoirs. Our results confirm the contribution of FOC in modern soils and rivers and display the various influences of weathering and erosional processes on the fate of FOC during its exchange between these pools. In addition, the contrasting behaviour of these markers upon the supergene processes has also highlighted the refractory or labile characters of the fossil organic matter (FOM). Bedrock to river fluxes, controlled by gully erosion, are characterized by a qualitative and quantitative preservation of FOM. Bedrock to alterite fluxes, governed by chemical weathering, are characterized by FOC mineralization without qualitative changes in deeper alterites. Alterite to soils fluxes, controlled by (bio)chemical weathering, are characterized by strong FOC mineralization and qualitative changes of FOM. Thus weathering and erosional processes induce different FOM evolution and affect the fate of FOC towards the global carbon cycle. In this study, gully erosion would involve maintenance of an ancient sink for the global carbon cycle, while (bio)chemical processes provide a source of CO2. Finally, this study suggests that Rock‐Eval 6 pyrolysis can be considered as a relevant tool for tracking FOC in modern environments. Copyright © 2006 John Wiley & Sons, Ltd.
Tea, hormone‐related cancers and endogenous hormone levels
Authors: Wu Anna H. , Yu Mimi C. 
Published: February 2006

AbstractTea is one of the most popular beverages consumed around the world, second only to water. There has been substantial interest in the potential role of tea in cancer prevention, particularly in respiratory and gastrointestinal tract cancers. Recent epidemiological data have linked tea intake to reduced risk of hormone‐related cancers, including breast, ovarian and prostate cancers. Based on sparse data, there is suggestion that tea intake may influence circulating hormone levels, providing a plausible mechanism whereby tea intake may influence risk of hormone‐related cancers. The major objectives of this paper are to review the epidemiological evidence on tea and risk of breast, ovarian, and prostate cancers as well as the human and non‐human studies on tea and circulating hormone levels. We pay special attention to some of the limitations of the human studies and discuss future research needs.
Intracellular signaling network as a prime chemopreventive target of (–)‐epigallocatechin gallate
Authors: Na Hye‐Kyung , Surh Young‐Joon 
Published: February 2006

AbstractChemoprevention is an attempt to use either naturally occurring or synthetic substances or their mixtures to intervene in the progress of carcinogenesis. Recently, it has been shown that some edible phytochemicals alter gene expression, directly or indirectly, thereby regulating the carcinogenic processes. (–)‐Epigallocatechin gallate (EGCG), a principal antioxidant derived from green tea, is one of the most extensively investigated chemopreventive phytochemicals. EGCG has been known to block each stage of carcinogenesis by modulating signal transduction pathways involved in cell proliferation, transformation, inflammation, apoptosis, metastasis and invasion. This review addresses the molecular target‐based chemoprevention with EGCG by focusing on the common events mediated by transcription factors, such as NF‐kappa B, activator protein‐1 and nuclear factor erythroid 2 p45‐related factor, and upstream kinases involved in the cellular signaling network.
X‐ray powder diffraction study of the Cu2Cd1–xMnxSnSe4 alloys
Authors: Sachanyuk V. P. , Olekseyuk I. D. , Parasyuk O. V. 
Published: February 2006

AbstractThe alloys of the Cu2CdSnSe4–Cu2MnSnSe4 system were investigated using the X‐ray powder method that showed the continuous solubility of the original system components at 670 K. The refinement of the crystal structures of Cu2MnSnSe4 (space group (SG) I&4macr;2m, a = 0.57362(4) nm, c = 1.14007(7) nm, c/a = 1.9875, RI = 0.0531, RP = 0.1186) and of the solid solution of Cu2Cd0.5Mn0.5SnSe4 composition (SG I&4macr;2m, a = 0.57935(2) nm, c = 1.14036(5) nm, c/a = 1.9683, RI = 0.0455, RP = 0.0902) was performed. It was established that Cd mixes statistically with Mn in its crystallographic position. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thermal development of microstructure and precipitation effects in Mg–10wt%Gd alloy
Authors: Čížek Jakub , Procházka Ivan , Smola Bohumil , Stulíková Ivana , Kužel Radomír , Matěj Zdeněk , Cherkaska Viktoria 
Published: February 2006

AbstractThermal effects on the microstructure and precipitation in Mg–10wt%Gd alloy were studied in this work. The role of lattice defects was investigated using positron annihilation spectroscopy. Studies of defects by positron annihilation were combined with X‐ray diffraction and microhardness measurements. Vacancies bound to Gd atoms were found in the homogenised sample quenched down to room temperature. Subsequently, clustering of Gd atoms takes place with increasing temperature. The Gd‐rich clusters represent precursors for further precipitates of the β″ phase. The formation of fine β″ phase particles leads to a maximum in the hardness. Vacancy‐like misfit defects are introduced by precipitation of β′ phase particles in the sample annealed to higher temperatures. A good correlation between the intensity of trapped positrons and the contribution by positrons annihilating Gd electrons was found. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Reactive magnetron sputtering of highly (001)‐textured WS2−x films: Influence of Ne+, Ar+ and Xe+ ion bombardment on the film growth
Authors: Ellmer K. , Seeger S. , Sieber I. , Bohne W. , Röhrich J. , Strub E. , Mientus R. 
Published: February 2006

AbstractTungsten disulfide WS2 is a layer‐type semi‐conductor with an energy band gap and an absorption coefficient making it suitable as an absorber for thin film solar cells. In the article [1] WS2–x films were pre‐pared by reactive magnetron sputtering from a metallic tungsten target in Ar–H2S atmospheres.The cover figure shows in situ energy‐dispersive X‐ray diffraction patterns for films deposited at different substrate potentials, i.e. for deposition conditions with ion assistance at different ion energies. These spectra and the corresponding SEM photographs of the film morphology show the strong influence of the ion energy on the film growth. The crystallographic struc‐ture of WS2–x is shown between the two SEM pictures.The first author, Klaus Ellmer, is working at the Hahn‐Meitner‐Institut Berlin, Dept. of Solar Energy Research. His research fields are thin film deposition by reactive magnetron sputtering for solar cells, plasma characterization, in situ energy‐dispersive X‐ray diffraction and electronic transport in transpar‐ent conductive oxides.
Carbon nanotube – molecular resonant tunneling diode
Authors: Pandey Rajeev R. , Bruque Nicolas , Alam Khairul , Lake Roger K. 
Published: February 2006

AbstractIn the Rapid Research Letter [1] carbon nanotube (CNT) molecular resonant tunnel diodes (RTD) are proposed to complement bio‐assembled CNT field effect transistors. The cover figure is a schematic representation of a model CNT–pseudopeptide–CNT device in its relaxed structure with hydrogen passivation at the CNT ends. The device has been shown to exhibit the typical current–voltage response of an RTD.The first author, Rajeev Pandey, works as a post‐doctoral researcher in the Laboratory for Terascale and Terahertz Electronics, headed by Roger Lake, at Riverside.The current issue of physica status solidi (a) also contains the Feature Article “On the growth mechanisms of nanocrystalline diamond films” by Wilhelm Kulisch and Cyril Popov [2].
Optimal Abdominal Incision for Partial Hepatectomy: Increased Late Complications with Mercedes‐type Incisions Compared to Extended Right Subcostal Incisions
Authors: D’Angelica Michael , Maddineni Sridevi , Fong Yuman , Martin Robert C.G. , Cohen Michael S. , Ben‐Porat Leah , Gonen Mithat , DeMatteo Ronald P. , Blumgart Leslie H. , Jarnagin William R. 
Published: February 2006

AbstractIntroductionThe optimal abdominal incision for partial hepatectomy has not been established.MethodsA prospective hepatobiliary surgery database was retrospective reviewed. Patients with Mercedes and extended right subcostal (ERSC) incisions were identified and compared.ResultsBetween December 1991 and September 2001 a total of 1426 patients met the inclusion criteria. Among them, 856 (60%) had a Mercedes incision and 570 (40%) an ERSC incision. The two groups were well matched for demographics and operative variables. Perioperative morbidity and pulmonary complications were similar for the two groups as well. There was no difference in terms of early wound complications, although incisional hernias occurred in 9.8% of patients with a Mercedes incision compared to 4.8% of those with an ERSC incision (P = 0.0001.) On multivariate analysis, the incision type, along with gender, body mass index, and age, were significant predictors of incisional hernia.ConclusionsAn ERSC incision for partial hepatectomy provides adequate, safe access and is associated with fewer long‐term wound complications.
Correlations between Vitamin D Status and Biochemical/Clinical and Pathological Parameters in Primary Hyperparathyroidism
Authors: Özbey Neşe , Erbil Yeşim , Ademoğlu Evin , Özarmağan Selçuk , Barbaros Umut , Bozbora Alp 
Published: February 2006

AbstractBackgroundTo determine the prevalence of vitamin D deficiency and the effects of vitamin D status on parathyroid adenoma weight, clinical and biochemical indices in patients with primary hyperparathyroidism (pHPT) were studied.MethodsEighty patients with pHPT who underwent surgical treatment and in whom the presence of parathyroid adenoma were confirmed histopathologically were studied retrospectively from recorded data files. Patients were divided into three groups: patients with 25‐hydroxyvitamin D (25‐OHD) concentrations < 15 ng/ml (group 1, n = 44), patients with 25‐OHD concentrations > 15–25 ng/ml (group 2, n = 9), and patients with 25‐OHD concentrations > 26 ng/ml (group 3, n = 27). Serum calcium, phosphate, alkaline phosphatase, creatinine, and albumin levels and urinary calcium excretion were determined by auto‐analyzer. Plasma 25‐OHD and parathyroid hormone (PTH) levels were determined by immunoradiometric assay using commercially available kits.ResultsNo statistically significant differences were observed with respect to serum calcium, phosphorus, albumin, and creatinine concentrations between these groups. Serum PTH, alkaline phosphatase concentrations, urinary calcium excretion, parathyroid adenoma weight, and postoperative sixth month PTH concentrations were significantly higher in group 1 patients than in group 2 and group 3 patients. Significant correlations were observed between parathyroid adenoma weight and serum 25‐OHD concentrations (r = −0.348, P = 0.020); parathyroid adenoma weight and urinary calcium excretion (r = 0.348, P = 0.021). Multiple regression analysis revealed that parathyroid adenoma weight, serum 25‐OHD, and preoperative PTH concentrations correlated independently and significantly with postoperative sixth month PTH concentrations.ConclusionsVitamin D deficiency leads to more severe bone disease, increased parathyroid tumor growth, and delayed postoperative recovery of parathyroid function in patients with primary hyperparathyroidism.
Supplementary research of clinoptilolite-rich tuff composites after adsorption trials using the XPS technique
Authors: Chmielewská Eva , Tylus Wlodzimierz , Morvová Marcela 
Published: February 2006

AbstractThe paper deals with fabrication of carbonized and hydrophobized clinoptilolite-rich tuff using organic carbon rich substances, here particularly starch and waste vegetable residues, which were pyrolytically combusted and covered the external zeolite surface. Hydrophobization of the zeolite external surface was accomplished by octadecylammonium surfactant. Both surface modified clinoptilolite-rich tuffs were tested and compared with each other with regard to removal of organic (phenol) and inorganic (chromate, arsenate) pollutants from aqueous solutions. These elaborated composites with surface adsorbed pollutant species were analysed by X-ray photoelectron spectroscopy (XPS).
Assessment of the impact of a phosphatic fertilizer plant on the adjacent environment using fuzzy logic
Authors: Szczepaniak K. , Sârbu C. , Astel A. , Raińska E. , Biziuk M. , Culicov O. , Frontasyeva M.V. , Bode P. 
Published: February 2006

AbstractThe impact of a phosphatic fertilizer plant on the adjacent environment was examined. Selected rare earth elements, heavy metals and metalloids were determined in substrates and products, waste by-product, and grass and soil samples. Concentration gradients of elements in grass and soil samples along the southerly and easterly directions were examined and compared with the content of interior soil and grass samples, substrates, and products. Results were compared with available data on soil permissible element concentration levels. Two fuzzy principal component analysis (FPCA) methods for robust estimation of principal components were applied and compared with classical PCA. The efficiency of the new algorithms is illustrated. The investigation explored the impact of the plant on the adjacent environment. The most reliable results, in good agreement with types of samples, were produced using the FPCA-O algorithm
Environmental and economic comparison of waste solvent treatment options
Authors: Benko Tamas , Szanyi Agnes , Mizsey Peter , Fonyo Zsolt 
Published: February 2006

Abstract
The sustainable development and consumption need more efficient use of natural resources. As a consequence, the use of industrial solvents demands their recovery instead of end-of-pipe treatment. It is not always clear, however, which treatment alternative should be applied. Based on an industrial case study, the environmental and economic evaluation and comparison of the treatment alternatives of a non-ideal solvent mixture containing azeotropes is investigated for determining the preferable option. For the recovery of the industrial solvent mixture, two different separation alternatives are evaluated: a less effective alternative and a novel design based on hybrid separation tools. An end-of-pipe treatment alternative, incineration, is also considered and the split of the solvent mixtures between recovery and incineration is investigated. The environmental evaluation of the alternatives is carried out using ‘Eco-indicator 99 life-cycle impact assessment methodology’. Economic investigation is also accomplished. The economic features clearly favour the total recovery, however, the environmental evaluation detects that if a recovery process of low efficiency is applied, its environmental burden can be similar or even higher than that of the incineration. This motivates engineers to design more effective recovery processes and reconsider the evaluation of process alternatives at environmental decision making.