bluuebunny/crossref_metadata_2025_split huggingface dataset:
Single‐cell gel electrophoresis (the comet assay): Loops or fragments?
Authors: Shaposhnikov Sergey A. , Salenko Veniamin B. , Brunborg Gunnar , Nygren Jonas , Collins Andrew R. 
Published: June 2008

AbstractSingle‐cell gel electrophoresis, or the comet assay, is widely used to measure DNA damage and repair. Upon electrophoresis, the DNA of lysed, agarose‐embedded cells known as nucleoids, extends towards the anode in a structure resembling a comet, the relative intensity of the tail reflecting the frequency of DNA breaks. The structural organization of the DNA within comet preparations is not fully understood. We have used fluorescent in situ hybridization with large‐insert genomic probes and human Cot‐I DNA to investigate whether the production of the comet tail is simply explained by the relaxation of supercoiled DNA loops. We find that, under neutral electrophoresis conditions, when the tail and head DNA are double‐stranded, the probed sequence of DNA is seen as a linear array, consistent with extension from a fixed point on the nuclear core or matrix. After alkaline electrophoresis, the appearance of the fluorescent probes suggests that linear DNA has coalesced into a granular form.
Carbon nanotube disposable detectors in microchip capillary electrophoresis for water‐soluble vitamin determination: Analytical possibilities in pharmaceutical quality control
Authors: Crevillén Agustín G. , Pumera Martin , González María Cristina , Escarpa Alberto 
Published: June 2008

AbstractIn this work, the synergy of one mature example from “lab‐on‐chip” domain, such as CE microchips with emerging miniaturized carbon nanotube detectors in analytical science, is presented. Two different carbon electrodes (glassy carbon electrode (GCE) 3 mm diameter, and screen‐printed electrode (SPE) 0.3 mm×2.5 mm) were modified with multiwalled carbon nanotubes (MWCNTs) and their electrochemical behavior was evaluated as detectors in CE microchip using water‐soluble vitamins (pyridoxine, ascorbic acid, and folic acid) in pharmaceutical preparations as representative examples. The SPE modified with MWCNT was the best electrode for the vitamin analysis in terms of analytical performance. In addition, accurate determination of the three vitamins in four different pharmaceuticals was obtained (systematic error less than 9%) in only 400 s using a protocol that combined the sample analysis and the methodological calibration.
Rapid characterization of fatty alcohol ethoxylates by non‐aqueous capillary electrophoresis
Authors: Arias Mónica , Bauza Roberto , Rodríguez Juana , Castañeda Gregorio , Ríos Ángel 
Published: June 2008

AbstractFatty alcohol ethoxylates (FAE) (a mixture of nonionic surfactants) have been characterized using NACE with UV detection. Phenyl polyurethane derivatives of these compounds were previously obtained by reaction with phenyl isocyanate. The derivatization reaction only requires microwave irradiation for 30 s (600 W). Phenyl polyurethanes were separated and characterized using a BGE containing a mixture of ammonium nitrate (15 mM), acetic acid (1.5%) and 9:1 v/v methanol/ACN. After optimization of the instrumental conditions for the separation, phenyl polyurethane compounds (formed from the corresponding FAE) with ethylene oxide numbers (EON) of 6 (certified standard and industrial samples), 7 and 10 (both as industrial samples), and 5.5 (microemulsion phase) were successfully separated and characterized. The properties of these FAE nonionic surfactants are very important in the petroleum industry, which requires characterization of the quality of the purchased materials as well as the final products in the microemulsion‐oil‐water stream process. This analytical objective has been achieved by the proposed NACE methods, allowing FAE to be distinguished from 5.5 to 10 EON with errors below 4%, and shows advantages against to HPLC methods.
A high‐throughput multicomponent screening method for diuretics, masking agents, central nervous system (CNS) stimulants and opiates in human urine by UPLC–MS/MS
Authors: Thörngren John‐Olof , Östervall Fredrik , Garle Mats 
Published: June 2008

AbstractA simple and rapid multicomponent screening method of 130 substances for direct injections of urine samples has been developed. The fully automated method based on ultra‐performance liquid chromatography (UPLC) and tandem mass spectrometry (MS/MS) is used for three different classes of doping agents: diuretics, central nervous system stimulants (CNS stimulants) and opiates. The samples are diluted with buffer containing internal standards (IS) by a pipetting robot system into 96‐well plates. Samples are injected on a reversed phase sub 2‐µm particle column connected to a fast polarity switching and rapid scanning tandem mass spectrometer with an electrospray interface. The software used to evaluate the results produced reports containing a small‐sized window for each component and a data table list with flags to indicate any adverse analytical findings in the sample. The report can also be processed automatically using an application software, which interpret the data and indicate if there is a suspicious sample. One 96‐well plate can be analyzed within 16 h. Copyright © 2008 John Wiley & Sons, Ltd.
Identification of zinc‐alpha‐2‐glycoprotein binding to clone AE7A5 antihuman EPO antibody by means of nano‐HPLC and high‐resolution high‐mass accuracy ESI‐MS/MS
Authors: Reichel Christian 
Published: June 2008

AbstractThe detection of doping with recombinant erythropoietins (Epo) by isoelectric focusing (IEF) and Western double blotting strongly relies on the specificity of the detection antibody used. Currently a monoclonal mouse antibody (clone AE7A5) is used for that purpose. Despite its excellent sensitivity (amol range) the antibody shows some nonspecific binding behavior. However, the binding occurs outside the currently used pH range for evaluating erythropoietin IEF profiles. A shotgun proteomics approach is described consisting of preparative IEF on large‐sized carrier ampholyte gels (pH 3–5), SDS‐PAGE, Western single and double blotting, on‐membrane elution of intact proteins, on‐membrane and in‐solution tryptic digestions, as well as nano‐HPLC peptide separation and high‐resolution high‐mass accuracy ESI‐MS/MS peptide sequencing. The nonspecifically interacting protein could be identified as zinc‐alpha‐2‐glycoprotein (ZAG). Confirmation analyses were performed using recombinant ZAG (rhZAG) and a monoclonal anti‐ZAG antibody. It could be demonstrated that the binding of the monoclonal antihuman EPO antibody (clone AE7A5) to ZAG occurs in a highly concentration‐dependant manner and that only samples containing increased amounts of urinary ZAG lead to a detectable interaction of the AE7A5 antibody on Epo‐IEF gels. Copyright © 2008 John Wiley & Sons, Ltd.
Synthesis and identification of hydroxylated metabolites of the anti‐estrogenic agent cyclofenil
Authors: Gärtner Peter , Hofbauer Karin , Reichel Christian , Geisendorfer Thomas , Gmeiner Günter 
Published: June 2008

AbstractThe detection of metabolites of the anti‐estrogenic substance cyclofenil, listed on the World Anti‐Doping Agency (WADA) Prohibited List since 2004 is described. Target substances are hydroxylated metabolites, bearing an aliphatic hydroxyl group either in the 2‐, 3‐ or 4‐position of the aliphatic ring, in addition to the phenolic functions on the aromatic rings. Structural identification used NMR as well as high‐resolution mass spectrometry after nano‐electrospray ionisation (ESI). Unambiguous detection of all three synthesised cyclofenil metabolites M1M3 was done using gas chromatography for separation and electron ionisation mass spectrometry for detection of the per‐silylated compounds in comparison with a reference urine deriving from an excretion study within the WADA 2007 Educational Programme. Copyright © 2008 John Wiley & Sons, Ltd.
Hydrogels for Potential Colon Drug Release by Thiol‐ene Conjugate Addition of a New Inulin Derivative
Authors: Pitarresi Giovanna , Tripodo Giuseppe , Calabrese Rossella , Craparo Emanuela Fabiola , Licciardi Mariano , Giammona Gaetano 
Published: June 2008

AbstractInulin was chosen as a starting polymer for biocompatible, pH‐sensitive and biodegradable hydrogels. Three INUDVSA‐TT hydrogels were obtained by crosslinking inulin derivatives with trimethylolpropane tris(3‐mercaptopropionate) under varying conditions. The resulting hydrogels were cell compatible, as demonstrated by MTS and trypan blue exclusion assays acting on Caco‐2 cells, and were biodegraded by inulinase and esterase, thus suggesting their use as colonic drug delivery systems. 2‐Methoxyestradiol, an anti‐cancer drug, was soaked in INUDVSA‐TT hydrogels and its in vitro release and apoptotic effect on Caco‐2 cells were evaluated.magnified image
Generalized Reconstruction by Inversion of Coupled Systems (GRICS) applied to free‐breathing MRI
Authors: Odille Freddy , Vuissoz Pierre‐André , Marie Pierre‐Yves , Felblinger Jacques 
Published: June 2008

AbstractA reconstruction strategy is proposed for physiological motion correction, which overcomes many limitations of existing techniques. The method is based on a general framework allowing correction for arbitrary motion–nonrigid or affine, making it suitable for cardiac or abdominal imaging, in the context of multiple coil, arbitrarily sampled acquisition. A model is required to predict motion in the field of view at each sample time point, based on prior knowledge provided by external sensors. A theoretical study is carried out to analyze the influence of motion prediction errors. Small errors are shown to propagate linearly in that reconstruction algorithm, and thus induce a reconstruction residue that is bounded (stability). Furthermore, optimization of the motion model is proposed in order to minimize this residue. This leads to reformulating reconstruction as two inverse problems which are coupled: motion‐compensated reconstruction (known motion) and model optimization (known image). A fixed‐point multiresolution scheme is described for inverting these two coupled systems. This framework is shown to allow fully autocalibrated reconstructions, as coil sensitivities and motion model coefficients are determined directly from the corrupted raw data. The theory is validated with real cardiac and abdominal data from healthy volunteers, acquired in free‐breathing. Magn Reson Med 60:146–157, 2008. © 2008 Wiley‐Liss, Inc.
Multiscale roughness analysis in injection‐molding process
Authors: Bigerelle Maxence , Van Gorp Adrien , Iost Alain 
Published: June 2008

AbstractThe roughness of polymer surfaces is often investigated to guarantee both the surface integrity and the surface functionality. One of the major problems in roughness measurement analyses consists in determining both the evaluation length and the reference line (i.e., the degree of the polynomial equation) from which roughness parameters are computed. This article outlines an original generic method based on the generalized analysis of variance and experimental design methodology for estimating the most relevant roughness parameter p, the most pertinent scale, s, and finally, the degree of the polynomial fitting, d. This methodology is then applied to characterize the influence of four process parameters on the final roughness of poly(polypropylene) samples obtained by injection molding. This method allows us to determine the most efficient triplet (p, s, d) that best discriminates the effect of a process parameter q. It is shown that different (p, s, d) values are affected to each process parameter giving finally the scale on which each process parameter modifies the roughness of a polymeric surface obtained by injection molding. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Supercritical carbon dioxide‐induced melting temperature depression and crystallization of syndiotactic polypropylene
Authors: Li Bin , Zhu Xinyuan , Hu Guo‐Hua , Liu Tao , Cao Guiping , Zhao Ling , Yuan Weikang 
Published: June 2008

AbstractThis work was aimed at studying supercritical carbon dioxide (scCO2)‐induced melting temperature depression and crystallization of a syndiotactic polypropylene (sPP). Under scCO2, the melting temperature of the sPP could be significantly reduced depending on the CO2 pressure. The scCO2‐induced crystallization of sPP was investigated using differential scanning calorimeter (DSC) and Fourier transform infrared spectroscopy. Two melting peaks were observed in DSC. The one at lower melting temperature referred to the melting of the sPP crystals induced by scCO2 in its amorphous phase. Its location was shifted to higher temperature, and its area increased with increasing scCO2 treatment time, temperature, and pressure. The melting peak at higher temperature corresponded to the melting of the sPP crystals that already existed before scCO2 treatment. Its location and area remained almost unaffected by the scCO2 treatment. The scCO2‐induced crystallization was related to scCO2‐promoted transformation of the mesophase form III of the sPP to the stable form I. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Precipitation fronts and the reflection and transmission of tropical disturbances
Authors: Pauluis Olivier , Frierson Dargan M. W. , Majda Andrew J. 
Published: June 2008

AbstractThis paper investigates the interactions between precipitation and the circulation in an idealized model for the tropical atmosphere where convection is represented by a quasi‐equilibrium closure. When studying large‐scale circulation in the Tropics, the governing equations can be further simplified by making the strict quasi‐equilibrium assumption which considers that convection acts to instantaneously adjust the atmospheric temperature profile to a moist adiabatic lapse rate. It is shown here that, under this assumption, the interface between the precipitating and non‐precipitating regions exhibits a discontinuity in the precipitation rate and vertical velocity. Furthermore, this interface, referred to as a precipitation front, moves at a velocity distinct from the propagation speed of dry and moist disturbances. The theory predicts the existence of three types of precipitation fronts: drying fronts, slow moistening fronts and fast moistening fronts. In previous studies, numerical simulations have demonstrated the existence of the three types of front, and have also confirmed that the precipitation front theory offers a good approximation for the behaviour of the interface between dry and moist regions for finite value of the convective adjustment time.A new framework is proposed here in which the encounter of an atmospheric disturbance and the edge of a precipitation region is recast as a Riemann problem. It is shown that, for any precipitation fronts, there are three incident characteristics but only two outgoing characteristics. This makes it possible to solve simultaneously for the intensity of the outgoing invariants and the propagation speed of the front. This also implies that atmospheric disturbances will be partially transmitted and partially reflected when encountering a precipitation front. For small perturbations, linear reflection and transmission coefficients can be computed analytically. These results also indicate that that disturbances can be amplified through over‐transmission or over‐reflection. These theoretical results are confirmed in numerical simulations of an idealized Walker circulation. A solution that includes a stationary precipitation front is perturbed by adding a small‐amplitude gravity wave, convectively coupled gravity wave, or moisture disturbance. All numerical simulations exhibit reflection and transmission of the incoming signal, and one simulation shows a case of over‐transmission of the incoming disturbance. Copyright © 2008 Royal Meteorological Society
In situ Synthesis of Lipopeptides as Versatile Receptors for the Specific Binding of Nanoparticles and Liposomes to Solid‐Supported Membranes
Authors: Schuy Steffen , Treutlein Barbara , Pietuch Anna , Janshoff Andreas 
Published: June 2008

AbstractA detailed study of the in situ coupling of small peptides such as CGGH6 (H6) and CGWK8 (K8) to maleimide functionalized phospholipid bilayers is presented. Individually addressable microstructured membranes are employed to unequivocally probe the conjugation. The in situ coupling of peptides via a terminal cysteine moiety to maleimide functionalized phospholipids is shown to be a convenient and versatile way to selectively fabricate peptide‐modified phospholipid bilayers serving as specific receptor platforms for functionalized vesicles and nanoparticles. Specific binding of functional vesicles to the peptide‐modified bilayers is achieved by either histidine complexation with Ni‐NTA‐DOGS containing vesicles or electrostatic interaction between positively charged oligolysine bearing lipopeptides and negatively charged POPC/POPG vesicles. Peptide receptors are also found to be easily accessible from the aqueous phase and not buried within the membrane interior.
Circadian and ultradian rhythms in the crayfish caudal photoreceptor
Authors: Rodríguez‐Sosa Leonardo , Calderón‐Rosete Gabina , Flores Gonzalo 
Published: June 2008

AbstractThe study of circadian clocks in crustaceans has led to the hypothesis of a distributed circadian system of pacemakers. In this review, we investigate the role of the crayfish caudal photoreceptor (CPR) as a candidate to form part of this pacemaking circadian system. Two circadian rhythms are documented for CPR electrical activity. These rhythms correspond to the spontaneous and light‐induced discharge of action potentials. The intrinsic characterization of the rhythms is made through the analysis of the firing rate of the corresponding action potentials. The discharges were extracellularly recorded in the isolated 6th abdominal ganglion (AG) in an organ culture kept at constant temperature for up to 5 days. For preparations kept in the dark, spontaneous activity varies in a circadian manner, with a period of 24.7 h and the acrophase at subjective nighttime (2140). For light‐induced activity, pulses of constant intensity applied regularly throughout the 24‐h cycle show that the firing rate at peak and latency vary rhythmically. The period for this rhythm is 24.24 h and the acrophase is at subjective dawn (0326). Additionally, an ultradian rhythm of a ∼12‐h period was observed for both rhythms. When tested with light pulses of different intensities, the CPR responsiveness at night is almost one log unit greater than in daytime. The effect of temperature on both activities is also described. The phase‐shift caused by temperature for these circadian rhythms depends on the application time. These results show that the 6th AG is capable of generating a circadian rhythm of electrical activity in the CPR, which in turn is likely to be part of the crayfish circadian system. A possible interaction of different pacemakers forming the distributed circadian system is also discussed. The role of serotonin as a possible modulator of the CPR electrical activity is documented. In addition, the level of the 5‐HT1Areceptors displays a diurnal rhythm in the 6th AG, with the acrophase at twilight (1849). We suggest that the 5‐HT1Areceptor does participate in this modulation. Finally, the hypothesis of the expression of two circadian oscillators in a single identified neuron is presented. Synapse 62:643–652, 2008. © 2008 Wiley‐Liss, Inc.
Mantle sources of Permian-Triassic Siberian traps (West Siberian Plate and Siberian craton)
Authors: Sharapov V.N. , Perepechko Yu.V. , Perepechko L.N. , Rakhmenkulova I.F. 
Published: June 2008

Abstract
We investigate the dynamics of multilevel subcontinental melting beneath a lithosphere of variable thickness as a model simulating generation of melts that produced flood basalt in the Siberian Trap province. The inferred sequence of volcanic events correlates with upper mantle decompression melting above hotspots and related conductive melting of metasomatized depleted lithosphere. Numerical experiments show that complex mafic magmatic systems of this kind are at least two-stage with a zone of decompression melting in upwelling mantle flow and a sub-Moho lithospheric melting region; the shallower lithospheric melting region can be disconnected from the mantle zone of decompression melting along the edges of the magmatic system; the lithospheric melting region has a particular layered structure with its top at a depth of 60–70 km and a maximum size exceeding the length of the erupted lava field; mafic melts produced at different levels of the system have different compositions.
Dating impact craters: palaeogeographic versus isotopic and stratigraphic methods – a brief case study
Authors: SCHMIEDER MARTIN , BUCHNER ELMAR 
Published: June 2008

AbstractIsotopic and stratigraphic ages of the ~ 80 km diameter Puchezh-Katunki (Russia; 220 ± 10 to 167 ± 3 Ma) and the ~ 20 km diameter Obolon (Ukraine; 215 ± 25 to 169 ± 7 Ma) impact structures are associated with significant age uncertainties. As a case study, reconstructions of the palaeogeography at the time of crater formation (Late Triassic to Middle Jurassic) based on recent palaeogeographic maps help further to constrain impact ages. Palaeogeographic studies suggest that Puchezh-Katunki is older than 170 Ma and that Obolon is younger than 185 Ma. This also rules out that Obolon formed during a ~ 214 Ma Late Triassic multiple impact event as recently discussed.
Thermal properties of operative endoscopes used in otorhinolaryngology
Authors: MacKeith S A C , Frampton S , Pothier D D 
Published: June 2008

AbstractObjectives:To measure the thermal properties of operative endoscopes used in otorhinolaryngological practice.Methods:A series of endoscopes of varying diameters and angulations were attached to a light source and temperature measurements taken of their shaft and tip; a measurement was also taken 5 mm in front of the endoscope tip.Results:Temperature changes took place rapidly. The amount of heat produced by the endoscopes was maximal at the tip, with larger diameter endoscopes attaining a higher temperature. Temperatures on the shaft and in front of the tip reached relatively constant temperatures independent of the type of endoscope. The maximum temperature achieved was 104.6°C for the 4 mm, 0° endoscope. Cooling occurred rapidly after the light source was switched off.Conclusion:The heat produced by some endoscopes is sufficiently great to cause thermal injury to tissues. Awareness of the temperatures produced by these endoscopes should prompt clinicians to actively cool their endoscopes during a procedure, before any thermal injury is caused.