bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of Iron Sulfide Species in Model Solutions by Cyclic Voltammetry. Revisiting an Old Problem
Authors: Bura‐Nakić E. , Krznarić D. , Helz G. R. , Ciglenečki I. 
Published: May 2011

AbstractA long‐standing problem associated with voltammetric determination of iron and sulfide in reduced natural waters has been the nature of the presumed analyte responsible for a reduction peak at −1.1 V vs. Ag/AgCl. Cyclic voltammetry at the Hg electrode is used here to study solutions with different Fe(II) to sulfide ratios in chloride and acetate electrolytes (pH 6–7). The results indicate that the −1.1 V peak can be assigned to reduction of Fe2+ or its labile complexes on FeS layers that partially cover the Hg electrode. Hg electrodes covered with FeS act like FeS solid electrodes over a very wide potential range (−0.35 to −1.9 V). Two mechanisms for forming FeS layers on Hg are described. Over the broadest deposition potential range, the dominant mechanism involves attachment at the Hg surface of FeS nanoparticles, which are generated quickly in initially supersaturated mixtures of Fe(II) and S(–II). In a narrow deposition potential range, roughly −0.56 to −0.70, FeS layers are produced additionally by replacement of preformed HgS. Because Fe2+ is reduced at −1.1 V on FeS layers and at −1.4 V on bare Hg, it may be underdetermined when only the −1.4 V peak is measured.
Development of a Carbon Paste Electrode for Lactate Detection Based on Meldola’s Blue Adsorbed on Silica Gel Modified with Niobium Oxide and Lactate Oxidase
Authors: Pereira Arnaldo C. , Kisner Alexandre , Tarley César R. T. , Kubota Lauro T. 
Published: May 2011

AbstractA reagentless amperometric biosensor sensitive to lactate was developed. The sensor employs a carbon paste electrode modified with lactate oxidase (LOx) and Meldola’s Blue (MB) adsorbed on silica gel coated with niobium oxide. The dependence on the biosensor response was investigated in terms of pH, supporting electrolyte, ionic strength, lactate oxidase (LOx) amounts and applied potential. The biosensor showed an excellent operational stability (96 % of the activity was maintained after 150 determinations) and storage stability (allowing measurements for more than 1.5 months, when stored in a refrigerator). The proposed biosensor also presented good sensitivity allowing lactate quantification at levels down to 6.5×10−7 mol L−1. Moreover, the biosensor showed a good linear response range (from 0.1 to 5.0 mmol L−1 for lactate). Lactate analysis in biological samples such as blood was also performed. The precision of the data obtained by the proposed biosensor showed reliable results for real complex matrices.
Cationic poly(amidoamine) dendrimers as additives for capillary electroseparation and detection of proteins
Authors: Liu Qingchun , Tian Jing , Zhang Chenling , Yang Huan , Liu Yang , Qin Weidong , Liu Zhengping 
Published: May 2011

AbstractWe examine the influence of cationic poly(amidoamine) (PAMAM) dendrimers on capillary electroseparation–UV analysis of proteins. PAMAMs adsorbing to the capillary surface suppressed the wall‐adsorption of proteins; meanwhile, PAMAMs added to the buffer exhibited selectivity toward proteins. Presence of 3×10−4 g/mL PAMAM generation one (G 1.0) in 30 mM phosphate, at pH 2.6, rendered significant enhancement in separation efficiency; the merged peaks of myoglobin and trypsin inhibitor were separated. Moreover, the protein–dendrimer interactions changed the inherent UV absorbance profiles of proteins. UV–Vis study showed that the absorbance of cytochrome C and transferrin increased at the detection wavelength of 214 nm; their detection sensitivity enhanced by 2.44 and 2.01‐folds, respectively, with addition of 5×10−4 g/mL PAMAM G 1.0.
CEC separation of ofloxacin enantiomers using imprinted microparticles prepared in molecular crowding conditions
Authors: Shi Xiao‐Xu , Xu Liang , Duan Hong‐Quan , Huang Yan‐Ping , Liu Zhao‐Sheng 
Published: May 2011

AbstractMolecular crowding is a new concept to obtain molecularly imprinted polymers (MIPs) with greater capacity and selectivity, which could shift the equilibrium of a print molecule reacting with functional monomers in the direction of complex formation side. In this work, molecular crowding agent was first applied to the preparation of MIPs microparticles by precipitation polymerization. A new system of molecular crowding surrounding was developed, composed of polystyrene and tetrahydrofuran, in the presence of the template (S)‐ofloxacin. Partial filling capillary electrochromatography (CEC) was utilized to evaluate imprinting effect of the resulting microparticles by chiral separations of ofloxacin. Some important parameters in the preparation, i.e. template to monomer ratio, influence of cross‐linking monomers and functional monomer composition on the CEC separation of MIP microparticles were investigated. Baseline separation of ofloxacin (Rs=1.53) was obtained under optimized conditions and the highest theory plate of the later eluent (S)‐ofloxacin was 5400. The textural and morphological parameters for imprinted particles, such as Brunauer–Emmett–Teller surface areas, pore volumes and pore size distributions have also been determined. Compared to the MIP microparticle prepared by conventional precipitation polymerization, the (S)‐ofloxacin‐imprinted particles formed under molecular crowding conditions showed higher selectivity (α=1.09) and separation efficiency (<25 min) in the CEC mode.
Peptide fractionation by acid pH SDS‐free electrophoresis
Authors: Ramos Yassel , Garcia Yairet , Pérez‐Riverol Yasset , Leyva Alejandro , Padrón Gabriel , Sánchez Aniel , Castellanos‐Serra Lila , González Luis J. , Besada Vladimir 
Published: May 2011

AbstractSDS‐free polyacrylamide gel electrophoresis is an effective alternative approach to peptide fractionation. Here we describe a discontinuous buffer system at acid pH that improves the separation of acidic peptides from tryptic digestion. MOPS and chloride act as trailing and leading ions, respectively, in this system, while histidine operates as counterion and buffers all solutions. In these electrophoretic conditions, peptides with pI below 5.5 migrate with low overall electrophoretic mobilities but high differences from one another, which allows for their efficient resolution. In silico analysis of several proteomes shows that the acid pH system allows a peptide simplification of 2.5‐fold with respect to the total peptide mixture, and still a proteome coverage of about 95% is achievable. A straightforward method with a protocol including proteomic studies was achieved for SDS‐PAGE of proteins, enzyme treatment and further peptide fractionation by SDS‐free acid PAGE.
Electro‐osmotic flow in polygonal ducts
Authors: Wang Chang‐Yi , Chang Chien‐Cheng 
Published: May 2011

AbstractThe paper presents semi‐analytical solutions to electro‐osmotic (EO) flow through polygonal ducts under the Debye–Hückel approximation. Analytical series solutions assisted with numerical collocations are found to yield very fast convergence. The solutions have practical applications as the pores of EO membranes are mostly hexagonal, stacked densely in a beehive‐like matrix. In addition, we develop simple asymptotic approximations that would be applicable to all EO tube flows of small as well as large dimensionless electrokinetic width. This facilitates investigation of analytical structures of general EO flows in all shapes of tubes, including the present geometries. In particular, for thick electrical double layers, the flow rate of EO is related to the corresponding viscous Poiseuille flow rate, while for thin electrical double layers, the flow rate is shown to be characterized by the cross‐sectional area and the perimeter length of the tubes.
Synergistic use of several receptor models (CMB, APCS and PMF) to interpret air quality data
Authors: Andriani E. , Caselli M. , de Gennaro G. , Giove A. , Tortorella C. 
Published: May 2011

AbstractPM10 samples were collected in Civitavecchia (Rome, Italy) during a monitoring campaign performed between August and September 2008; elemental, ionic and organic characterisation of the samples was carried out. Three receptor models (Chemical Mass Balance, Absolute Principal Component Scores and Positive Matrix Factorisation) were applied to identify PM10 sources and their contributions. The results obtained by the models were compared in order to perform a robust characterisation of the sources.Seven emission sources were considered relevant for the area under investigation and their profiles were used to run CMB. Source percentage contributions to the total particulate matter samples were evaluated: the greater contribution was obtained for Traffic (39%), the lower for Marine Aerosol (3%).Five factors were selected to perform the multivariate receptor models (APCS and PMF) after the application of explorative Principal Component Analysis to the dataset. Furthermore, attention was focused on the characterisation of source profiles and contributions obtained by PMF because it best reconstructed the PM mass of the samples.The percentage contributions of the five sources to the total PM samples were estimated: the greater contribution was obtained for resuspended matter (22%), the lower for combustions (17%).The results of the source apportionment studies can be used by air quality managers to develop appropriate control strategy. However, the differences in sources profiles and weights obtained by the models were related to their specific approaches: further investigations are suggested in order to develop sources profiles more reliable for the area under investigation. Copyright © 2011 John Wiley & Sons, Ltd.
Near‐surface temperatures and heat balance of bare outcrops exposed to solar radiation
Authors: Gunzburger Yann , Merrien‐Soukatchoff Véronique 
Published: May 2011

ABSTRACTSubsurface temperatures in rocks naturally fluctuate under the influence of local meteorological conditions. These fluctuations play a role in mechanical weathering, thus creating the environmental conditions conducive to natural hazards such as rockfalls and providing important sediment source terms for landscape evolution. However, the physics that control heat penetration into rocks are not fully understood, which makes the underground thermal state difficult to interpret when temperature measurements are available and even more difficult to estimate for unmonitored sites. This is an important lacuna given possible impacts of future climate change on mechanical weathering processes.The natural daily variations of subsurface temperatures were investigated on a bare gneiss outcrop exposed to solar radiation, where temperatures at various depths (up to 50 cm), as well as the solar radiation reaching a pyranometer, were monitored hourly for several months. This detailed times series of thermal data was used to gain insight into the heat balance at the inclined free surface of the rock mass.Attention was focused on two major contributors to the heat balance; the heat flux entering the rock mass through conduction and the incoming shortwave (solar) radiation. A Fourier decomposition of the temperature measurements provided an estimate of the in situ thermal conductivity of the rock and was used to calculate the conductive term. The shortwave radiation term was determined on the basis of the pyranometer measurements adjusted to account for the angle of incidence of the sun.It is shown that, throughout clear‐sky periods, heat exchanges at the surface are mainly controlled by direct solar radiation during the day, and by a roughly constant outgoing heat flux during the night. Subsurface temperatures can be reliably estimated with a semi‐infinite medium model whose boundary condition is derived from an analytical insolation model that takes atmospheric attenuation into account. Copyright © 2011 John Wiley & Sons, Ltd.
1D‐Modelling and Experimental Study of the PEFC Dynamic Behaviour at Load Increase
Authors: Zaglio M. , Wokaun A. , Mantzaras J. , Büchi F. N. 
Published: May 2011

AbstractThe complex dynamic response of a 1‐dimensional polymer electrolyte fuel cell to load changes is numerically and experimentally investigated, in order to understand the transient transport processes in the different domains of the cell through the membrane‐electrode assembly. The analysis focuses on the comparison of cell response to step load changes, at different levels of reactants humidification. To render the model capable of capturing the cell behaviour at different operating conditions, a multiparameter optimisation procedure is performed to determine the most sensitive transport parameters. The optimisation procedure converges towards a well‐defined solution and the resulting parameters are compared to those available in the literature. Model results indicate that the time required to reach the new steady‐state after a load increase is controlled by the water transport in the membrane. The influence of the water diffusion coefficient at the different operating conditions is further investigated numerically.
Person‐centred care and job satisfaction of caregivers in nursing homes: a systematic review of the impact of different forms of person‐centred care on various dimensions of job satisfaction
Authors: van den Pol‐Grevelink A. , Jukema J.S. , Smits C.H.M. 
Published: May 2011

ObjectiveThe positive effects of person‐centred care on older clients have been demonstrated. However, relatively little is known about the effect that giving person‐centred care has on caregivers. This literature review examines the job satisfaction of caregivers who deliver person‐centred care in nursing homes.DesignThe research questions are: Do the various forms of person‐centred care affect job satisfaction differently? Which particular dimensions of job satisfaction have been evaluated in studies on person‐centred care, and does their sensitivity to person‐centred care differ? Using the search engines Pubmed, Cinahl, Psychinfo and Embase up to August 2010, 46 efficacy studies were found, seven of which satisfied our criteria.ResultsEmotion‐oriented care, snoezelen, and small‐scale care most often show positive effects on job satisfaction. Person‐centred care has been shown to have positive effects on general job satisfaction, job demands at psychogeriatric wards, emotional exhaustion and personal accomplishment.ConclusionsTaking into account the fair‐to‐moderate quality of the studies included, it is concluded that there are limited indications that person‐centred care has a positive effect on a number of dimensions of caregivers' job satisfaction. Further study is required to expand and to support these tentative conclusions. Copyright © 2011 John Wiley & Sons, Ltd.
Humanized tumor mice—A new model to study and manipulate the immune response in advanced cancer therapy
Authors: Wege Anja K. , Ernst Wolfgang , Eckl Judith , Frankenberger Bernhard , Vollmann‐Zwerenz Arabel , Männel Daniela N. , Ortmann Olaf , Kroemer Alexander , Brockhoff Gero 
Published: May 2011

AbstractThe immunological impact on antibody‐based anticancer therapies remains incompletely understood due to the lack of appropriate animal models for in vivo analysis. Here, we present a novel humanized tumor mouse (HTM) model, generated by concurrent transplantation of human hematopoietic stem cells (HSCs) and human breast cancer cells in neonatal NOD‐scid IL2Rγnull mice. Five weeks after intrahepatic transplantation, a functional human immune system was developed in all organs, and, in addition, tumor cells were detectable in lung and bone marrow (early dissemination). After 3 months posttransplant, tumor‐cell effusions and macroscopic tumors associated with liver or spleen were found. Furthermore, disseminated cells in different lymphoid and nonlymphoid organs were measurable. Tumor growth was accompanied by specific T‐cell maturation and tumor cell‐specific T‐cell activation. In addition, Natural–Killer cell accumulation and activation were observed in HTM, which was further enhanced upon IL‐15 treatment facilitating the possibility of immune cell modulation in, e.g., antibody‐dependent cellular cytotoxicity‐based immunotherapeutic approaches. This novel mouse model makes it possible to combine transfer of MHC mismatched tumor cells together with human HSCs resulting in a solid coexistence and interaction without evidence for rejection. Overall, humanized tumor mice represent a powerful in vivo model that for the first time permits the investigation of human immune system‐related target cancer therapy and resistance.
Ultrastable Host–Guest Complexes and Their Applications
Authors: Ko Young Ho , Hwang Ilha , Lee Don‐Wook , Kim Kimoon 
Published: May 2011

AbstractThis review describes monovalent synthetic receptor–ligand (or host–guest) pairs with extremely high binding affinity, comparable to that of the biotin–avidin pair, and their applications. Cucurbit[7]uril (CB[7]), a member of the host family cucurbit[n]uril (CB[n], n=5–8, 10), forms ultrastable host–guest complexes with ferrocene‐, adamantane‐ or bicyclo[2.2.2]octane‐based molecules having ammonium groups properly positioned to interact with the carbonyl oxygens at the portals of CB[7]. The extremely high affinity is achieved by a large enthalpic gain arising from the near perfect size/shape complementarity between the rigid CB cavity and the rigid core of the guest molecules, with the critical assistance of the positive entropy change due to the extensive dehydration of the host and guest. The high stability of the complexes allowed us and others to explore several biological applications such as immobilization of biomolecules on a solid surface, protein isolation, triggering intracellular events, and regulating enzymatic activities. These complexes with their exceptional affinity, chemical robustness, simple preparation, biocompatibility, and easy handling may replace the biotin–(strept)avidin system in diverse areas of research, including affinity chromatography, high throughput biochemical assays, imaging, and sensor technologies.
Deep Inside Cucurbiturils: Physical Properties and Volumes of their Inner Cavity Determine the Hydrophobic Driving Force for Host–Guest Complexation
Authors: Nau Werner M. , Florea Mara , Assaf Khaleel I. 
Published: May 2011

AbstractCucurbit[n]urils (CBn) bind guest molecules through a combination of electrostatic interactions with the carbonyl rims and hydrophobic interactions with the inner cavity. Investigations with solvatochromic probes in CB7 reveal that the polarity of the cavity resembles that of alcohols (e.g., n‐octanol), while its polarizability (P=0.12) and apparent refractive index (nD=1.10±0.12) are extremely low, close to the gas phase. The calculated molecular quadrupole moments of CBs are extremely large (Θzz=−120 to −340 Buckingham). A survey of reported binding constants of neutral guests and hydrophobic residues that form 1 : 1 inclusion complexes with CB6, reveals a preferential inclusion of C3–C5 residues in its cavity. The largest guests which show non‐negligible binding contain 7 heavy atoms (excluding hydrogen). For CB7, the strongest binding is observed for guests with adamantyl (10 heavy atoms) and ferrocenyl groups (11 heavy atoms), while the largest guests known to be complexed are carborane and the adduct of two pyridine derivatives (12 heavy atoms). The evaluation of different volumes shows that the most meaningful cavity, namely that responsible for binding of hydrophobic residues, is confined by the planes through the oxygen carbonyls. The volume of this inner cavity follows the formula V/Å3=68+62(n−5)+12.5(n−5)2, affording representative cavity volumes of 68 Å3 for CB5, 142 Å3 for CB6, 242 Å3 for CB7, and 367 Å3 for CB8. The volume of the 2 bond dipole regions is comparably smaller, amounting, for example, to 2×35 Å3 for CB6. The analysis of packing coefficients for representative sets of known guests with clearly defined hydrophobic binding motifs reveals average values of 47 % for CB5, 58 % for CB6, 52 % for CB7, and 53 % for CB8, which are well in line with the preferred packing (“55 % solution”, see S. Mecozzi, J. Rebek, Chem. Eur. J. 1998, 4, 1016–1022) in related supramolecular host–guest assemblies. The driving force for binding of hydrophobic guests and residues by CBs is interpreted in terms of the unimportance of dispersion interactions (owing to the low polarizability of their cavity) and the dominance of classical and nonclassical hydrophobic effects related to the removal of very‐high‐energy water molecules (2 for CB5, 4 for CB6, 8 for CB7, and 12 for CB8) from the cavity.
Improved adhesion of human cultured periosteal sheets to a porous poly(L‐lactic acid) membrane scaffold without the aid of exogenous adhesion biomolecules
Authors: Kawase Tomoyuki , Tanaka Takaaki , Nishimoto Takayuki , Okuda Kazuhiro , Nagata Masaki , Burns Douglas M. , Yoshie Hiromasa 
Published: May 2011

AbstractHuman cultured periosteal sheets, which are developed from small excised periosteum tissue segments (PTSs) in culture dishes by simple expansion culture, have been applied as a promising autologous osteogenic grafting material for periodontal regenerative therapy. However, the weak initial adhesion of PTSs to dish surfaces often hampers cellular outgrowth and limits the number of preparations. To correct this weakness and still avoid the use of animal‐derived adhesion biomolecules, we have developed a novel, biodegradable, porous poly(L‐lactic acid) (pPLLA) membrane. Freshly excised PTSs bound well to the highly porous pPLLA membrane, possibly due to the presence of semihemispheric 20–30 μm diameter openings on the upper surface. Global gene expression analysis demonstrated that periosteal sheets cultured on pPLLA membranes upregulated expression of many adhesion molecules. Osteogenic induction stimulated the production of proteoglycans by these cells and concomitantly enhanced their expansion and penetration into the deep pore regions of the membrane in parallel with the progression of in vitro mineralization. These findings suggest that our pPLLA membranes not only facilitate initial adhesion, primarily mediated by adsorbed proteins, but also enhance biological adhesion by inducing endogenous adhesion molecules in periosteal sheet cultures. Therefore, the efficacy of periosteal sheets in therapy should be greatly enhanced by using this new pPLLA membrane. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2011.
Preparation and characterization of antibacterial P2O5–CaO–Na2O–Ag2O glasses
Authors: Ahmed A. A. , Ali A. A. , Mahmoud Doaa A. R. , El‐Fiqi A. M. 
Published: May 2011

Abstract60P2O5–20CaO–(20 – x) Na2O–xAg2O and 60P2O5–30CaO–(10 – x) Na2O–xAg2O glasses, x = 0, 0.5,1, and 2 mol % were prepared using normal glass melting technique. The antibacterial activity of pressed disks of powdered glass (undoped and silver‐doped glass) was investigated against S.aureus, P.aeruginosa, and E.coli micro‐organisms using agar disk‐diffusion assays at 37°C for 24 h. The antibacterial activity was deduced from the inhibition zone diameter (IZD), zone of no bacterial growth, measured under the stated experimental conditions. The antibacterial activity increases with the increase in IZD and vice versa. Dissolution of glass in water at 37°C, pH changes of water during glass dissolution, and concentrations of silver ions released from silver‐doped glasses into water during their dissolution were determined. An increase in the concentration of silver ions released from silver‐doped glasses into water was observed with increasing time of glass dissolution and with increasing Ag2O content. The tested silver‐free and silver‐doped glasses demonstrated different antibacterial activity against the tested micro‐organisms. For silver‐free glasses, an increase in IZD was observed with the increase in the glass dissolution rate and with the decrease in pH of water. Also, the IZD showed an increase with increasing Ag2O content of silver‐doped glasses. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2011.