bluuebunny/crossref_metadata_2025_split huggingface dataset:
Precision in differential field‐flow fractionation: A chemometric study
Authors: Bregola Letizia , Contado Catia , Martin Michel , Pasti Luisa , Dondi Francesco 
Published: September 2007

AbstractIn the present paper, the capabilities of differential field‐flow fractionation, i. e., the determination of an incremental quantity of a colloidal species, e. g., an uptake adsorbed mass, determined by the joint use of two independent FFF measurements, over a species and the same modified species respectively, are considered. The different error types, those related to the retention time determinations and those coming from the operating parameter fluctuations were considered. The different components were computed with reference to SdFFF determinations of bare polystyrene (PS) submicronic particles and the same PS particles covered by IgG. Comparison was made between theoretically computed precision and experiments. The error coming from the experimental measurement of retention times was identified to be the main source of errors. Accordingly, it was possible to make explicit the detection limits and the confidence intervals of the adsorbed mass uptake, as a function of experimental quantities such as the retention ratio, the detector calibration ratio, the injected quantity, the baseline noise, and the void time relative error. An experimentally determined and theoretically foreseen dependence of both the experimental detection and confidence limits (∼︁ ± 10–17 g) on the square root of the injected concentration, for constant injected volume, was found.
Single‐step preparation and characterization of polymeric monolith for pressurized capillary electrochromatography of typical homologs
Authors: Lü Haixia , Wang Jiabin , Wang Xiaochun , Wu Xiaoping , Lin Xucong , Xie Zenghong 
Published: September 2007

AbstractA monolithic stationary phase was prepared in a single step by in situ copolymerization of iso‐butyl methacrylate (IBMA), ethylene dimethacrylate (EDMA), and N,N‐dimethylallylamine (DMAA) in a binary porogenic solvent consisting of N,N‐dimethylformamide (DMF) and 1,4‐butanediol. As the frame structures of monoliths, the amino groups are linked to support the EOF necessary for driving the mobile phase through the monolithic capillary, while the hydrophobic groups are introduced to provide the nonpolar sites for the chromatographic retention. To evaluate the column performance, separations of typical kinds of neutral or charged homologs, such as alkylbenzenes, phenols (including isomeric compounds of hydroquinone, resorcin, and catechol), and anilines (including isomeric compounds of o‐phenylenediamine and 1,4‐phenylenediamine), were performed, respectively on the prepared column under the mode of pressurized pCEC. Effects of the buffer pH and the mobile phase composition on the linear velocity of mobile phase and the retention factors of these compounds were investigated. It was found that the retention mechanism of charged solutes could be attributed to a mixed mode of hydrophobic interaction and electrophoresis, while an RP chromatographic behavior on the monolithic stationary phases was exhibited for neutral solutes. Especially, basic compounds such as anilines were well separated on the monolithic columns in the “counterdirectional mode,” which effectively eliminated the electrostatic adsorption of basic analytes on the charged surface of the stationary phases.
A reliable quantitative method for the analysis of phenolic compounds in Brazilian propolis by reverse phase high performance liquid chromatography
Authors: de Sousa João P. B. , Bueno Paula C. P. , Gregório Luiz E. , da Silva Filho Ademar A. , Furtado Niege A. J. C. , de Sousa Márcia L. , Bastos Jairo K. 
Published: September 2007

AbstractA sensitive and reliable RP‐HPLC method was developed using a C18 CLC‐ODS (M) – 4.6×250 mm2 column and gradient elution for the analysis of phenolic compounds in propolis raw material and its products. A procedure for the extraction of phenolic compounds using aqueous ethanol (90%) with the addition of veratraldehyde as the internal standard (IS) was developed allowing to quantify ten compounds: caffeic acid, coumaric acid, ferulic acid, cinnamic acid, aromadendrin‐4′‐methyl ether (AME), isosakuranetin, drupanin, artepellin C, baccharin, and 2,2‐dimethyl‐6‐carboxyethenyl‐2H‐1‐benzopyran acid (DCBEN). The developed method gave good detection response and linearity in the range of 20.83–533.33 μg/mL.
Performance of a dedicated light delivery and dosimetry device for photodynamic therapy of nasopharyngeal carcinoma: Phantom and volunteer experiments
Authors: Nyst H.J. , van Veen R.L.P. , Tan I.B. , Peters R. , Spaniol S. , Robinson D.J. , Stewart F.A. , Levendag P.C. , Sterenborg H.J.C.M. 
Published: September 2007

AbstractThe objective of this study was to develop a light delivery and measurement device for photodynamic therapy (PDT) in the nasopharyngeal cavity, which achieves a homogeneous and reproducible fluence rate distribution to a target area and provides proper shielding of predefined risk areas.Materials and MethodsA flexible silicone applicator was developed, incorporating light delivery and dosimetry fibers. The applicator can be inserted through the mouth and fixed in the nasopharyngeal cavity. Tissue optical phantoms were prepared on the basis of optical properties measured in vivo using diffuse reflectance spectroscopy (DRS). The fluence rate over the length of the applicator surface was measured in air, in tissue optical phantoms and in five healthy volunteers.ResultsThe fluence rate distribution over the applicator surface in air and tissue optical phantom was found to be more homogeneous (SD/mean 3.8% and 18.3%, respectively) than the fluence rate distribution in five volunteers (SD/mean ranging from 19% up to 52%). The maximum observed fluence rate build‐up in the nasopharynx varied between subjects and ranged from a factor of 4.1–6.9. Shielding of the risk area such as the soft palate and tongue was effective.ConclusionsIn air and in tissue optical phantoms the fluence rate distribution of the device was highly homogeneous. The observed inter‐subject and intra‐subject variations in fluence rate in healthy volunteers originated from differences in optical properties and nasopharyngeal geometry. Light delivery based on a single tissue surface measurement will not be adequate. In situ dosimetric measurements are required to determine the light fluence delivered to a geometrically complex site such as the nasopharynx. These observations should be taken in consideration when developing light applicators for PDT of the nasopharynx and other non‐uniform surfaces. Lasers Surg. Med. 39:647–653, 2007. © 2007 Wiley‐Liss, Inc.
Femtosecond laser corneal ablation threshold: Dependence on tissue depth and laser pulse width
Authors: Sun Hui , Han Meng , Niemz Markolf H. , Bille Josef F. 
Published: September 2007

AbstractBackground and ObjectiveDiode pumped, all‐solid‐state ultrafast lasers are now widely used to perform minimally invasive refractive surgery and keratoplasty procedures. Despite such use, a systematic study concerning ultrafast laser–tissue interactions is lacking. We determined the corneal ablation threshold as a function of the laser pulse width and stromal depth by simultaneous monitoring of the intensity of the laser‐induced plasma and the second harmonic generation signals (SHG) from the collagen.Study Design/Materials and MethodsAblation thresholds in porcine cornea samples were determined using three diode pumped all‐solid‐state ultrafast lasers (a Nd:glass femtosecond laser, a Yb:KYW femtosecond laser, and a Nd: YAG picosecond laser) over a range from 800 femtoseconds to 20 picoseconds.ResultsCorneal ablation threshold remained nearly constant within the first 200 µm of stroma and was consistent with previous findings with the threshold proportional to the square root of the laser pulse width.ConclusionCorneal ablation thresholds can be precisely determined by simultaneous monitoring of the intensity of the laser‐induced plasma and the SHG from the cornea. Lasers Surg. Med. 39:654–658, 2007. © 2007 Wiley‐Liss, Inc.
Prevention of third molar development in dog with long pulse diode laser: A preliminary report
Authors: Silvestri Anthony R. , Mirkov Mirko G. , Connolly Raymond J. 
Published: September 2007

AbstractIntroductionWisdom teeth continue to plague man with a high rate of frequency. It may be possible to prevent their development in children at an early age with a non‐ or minimally invasive technique, even before the tooth begins to form, by treating the soft tissue overlying the site of their development. A previous study that treated the intra‐oral soft tissues of newborn rats with a 20 watt diode laser stopped third molar development up to 80% of the time with minimum observable side effects. This brief report describes a similar use of the diode laser in a limited number of young beagle pups. It is the first reported attempt at preventing third molar development in an animal model close in size to man.Materials and MethodsFour 6–7 week old beagle pups were treated on one side of their mandibles with either a 20 or a 100 watt, 800 nm diode laser at a time third molar tooth buds are just beginning to form under the oral mucosa. Six months following treatment, the pups were examined intra‐orally and radiographically for evidence of third molar formation.ResultsThe two intra‐oral sites that received the 20 watt diode laser treatment showed normal third molar development. The two intra‐oral sites that received the 100 watt diode laser treatment did not develop third molars.ConclusionsThe diode laser may be capable of selectively stopping third molar development and further studies are warranted. Lasers Surg. Med. 39:674–677, 2007. © 2007 Wiley‐Liss, Inc.
Laser‐assisted end‐to‐end bioweld® anastomosis in an ovine model
Authors: Wright B. , Vicaretti M. , Schwaiger N. , Wu J. , Trickett R. , Morrissey L. , Rohanizadeh R. , Fletcher J. , Maitz P. , Harris M. 
Published: September 2007

AbstractThe BioWeld® tube, an albumin‐based exovascular stent, has been used for microsurgical anastomoses and compared to conventional sutures. The study presented investigated the potential of the BioWeld® tube for vascular anastomosis in larger vessels. Laser‐assisted BioWeld® anastomoses were compared to conventional‐sutured anatomoses of the carotid artery of Merino‐x ewes. The BioWeld® procedure resulted in 100% survival and 100% patency at 1 and 6 week post‐operative periods, with no noticeable foreign body response. Sutured animals showed 100% survival and patency. The ischemic time for BioWeld® anastomosis averaged 15 minutes compared with 10 minutes for sutures. This study indicates that the BioWeld® tube is an easy to use anastomotic technique with equivalent success rates and comparable anastomotic times. Lasers Surg. Med. 39:667–673, 2007. © 2007 Wiley‐Liss, Inc.
Frequency domain near‐infrared spectroscopy of the uterine cervix during cervical ripening
Authors: Baños Ana , Wolf Martin , Grawe Claudia , Stahel Michèle , Haensse Daniel , Fink Daniel , Hornung René 
Published: September 2007

AbstractObjectivePreterm labor is a common obstetric complication. Clinical evaluation of cervical ripening to predict preterm labor has a substantial inter‐ and intraobserver variability. We used frequency domain near‐infrared spectroscopy (FD‐NIRS) to non‐invasively investigate the changes of the optical properties (i.e., absorption and scattering of light) in the uterine cervix during drug‐induced cervical ripening.MethodsTen volunteers scheduled for abortion were examined. Optical properties of the uterine cervix were measured and physiological parameters were calculated prior to and after induction of cervical ripening using topical misoprostol. Mean relative changes, ±standard error of the mean as well as statistical significance using the t‐test were calculated for oxy‐ and deoxyhemoglobin, total hemoglobin, oxygen‐saturation, and water. The wavelength‐dependent decrease of scattering (scatter power) was calculated by an exponential fit and tested with the Wilcoxon test.ResultsMisoprostol induced a decrease in total hemoglobin of 21±6% (P<0.05), a decrease in oxyhemoglobin of 22±6% (P<0.05), a decrease in deoxyhemoglobin of 16±11% and an increase of 36±8% (P<0.005) in water content. The scatter power was significantly lower (P<0.05) after cervical ripening.ConclusionOur results show that FD‐NIRS is a promising diagnostic tool to detect changes in cervical concentrations of hemoglobin and water. A severe tissue edema, probably due to a hormone‐induced inflammatory process, seems to be important for cervical ripening. The reduction in total hemoglobin is likely to be a consequence of the increased water content of the tissue resulting in a dramatic increase of the distance between vessels. We propose this technology to assess the cervical ripening and eventually to predict preterm labor. Lasers Surg. Med. 39:641–646, 2007. © 2007 Wiley‐Liss, Inc.
A comparison of the FREDDY and holmium lasers during ureteroscopic lithotripsy
Authors: Yates Jennifer , Zabbo August , Pareek Gyan 
Published: September 2007

AbstractBackground and ObjectiveTwo laser devices that are used today in endoscopic treatment of renal and ureteral calculi are the frequency‐doubled double‐pulse neodynium:YAG (FREDDY) and Holmium:YAG lasers. The mechanism of action of these lasers differs, thus conferring potentially different safety and efficacy profiles. The in vitro efficacy of these lasers in treating urinary stones has been explored, but to our knowledge no study compares the in vivo efficacy. The purpose of this study is to compare the stone‐free and complication rates of the FREDDY and holmium lasers.Study Design/Materials and MethodsSubjects were included in the study (from January 2004 to September 2006) if they had adequate documentation of stone size and location, postoperative stone burden, and perioperative complications. Stone‐free status was determined based on intraoperative findings and postoperative imaging. Complications included bleeding, ureteral perforation, any intraoperative event necessitating termination of the procedure, ureteral stricture, hydronephrosis, and admission to the hospital with a diagnosis related to the procedure.ResultsSixty patients with adequate follow‐up were identified. Thirty patients were treated with FREDDY and 30 patients with Holmium laser. Fisher's exact test was employed for statistical analysis. There was no significant difference in the average stone size between the FREDDY and Holmium groups, which were 6.7 mm and 6.1 mm, respectively. Stone‐free rates in the FREDDY and Holmium groups were 76.7% and 93.3%, respectively, P = 0.149. The complication rates were 17.4% in the FREDDY group and 10% in the Holmium group, P = 0.667.ConclusionThe complication and stone‐free rates did not significantly differ between the FREDDY and Holmium lasers, though there was a trend toward a higher stone‐free rate and lower complication rate with the holmium laser. Holmium laser may be more effective than the FREDDY laser in fragmenting calcium oxalate monohydrate stones. The device and laser fiber costs were comparable. Lasers Surg. Med. 39:637–640, 2007. © 2007 Wiley‐Liss, Inc.
Surfactant‐Induced Amorphous Aggregation of Tobacco Mosaic Virus Coat Protein: A Physical Methods Approach
Authors: Panyukov Yuliy V. , Nemykh Maria A. , Dobrov Eugeny N. , Drachev Vladimir A. 
Published: September 2007

AbstractThe interactions of non‐ionic surfactant Triton X‐100 and the coat protein of tobacco mosaic virus, which is an established model for both ordered and non‐ordered protein aggregation, were studied using turbidimetry, differential scanning calorimetry, isothermal titration calorimetry, and dynamic light scattering. It was found that at the critical aggregation concentration (equal to critical micelle concentration) of 138 × 10−6 M, Triton X‐100 induces partial denaturation of tobacco mosaic virus coat protein molecules followed by protein amorphous aggregation. Protein aggregation has profound ionic strength dependence and proceeds due to hydrophobic sticking of surfactant‐protein complexes (start aggregates) with initial radii of 46 nm. It has been suggested that the anionic surfactant sodium dodecyl sulfate forms mixed micelles with Triton X‐100 and therefore reverses protein amorphous aggregation with release of protein molecules from the amorphous aggregates. A stoichiometric ratio of 5 was found for Triton X‐100‐sodium dodecyl sulfate interactions.magnified image
Mucoadhesive and Elastic Films Based on Blends of Chitosan and Hydroxyethylcellulose
Authors: Luo Kun , Yin Jingbo , Khutoryanskaya Olga V. , Khutoryanskiy Vitaliy V. 
Published: September 2007

AbstractMucoadhesive polymeric films have been prepared based on blends of chitosan and hydroxyethylcellulose. The blends have been characterized by IR spectroscopy, DSC, WAXD, TGA, SEM, and mechanical testing. It is demonstrated that the mechanical properties of chitosan are improved significantly upon blending with hydroxyethylcellulose. An increase in hydroxyethylcellulose content in the blends makes the materials more elastic. The thermal treatment of the blends at 100 °C leads to partial cross‐linking of the polymers and formation of water‐insoluble but swellable materials. The adhesion of the films towards porcine buccal mucosa decreases with increasing hydroxyethylcellulose content in the blends.magnified image
Understanding Segmental Dynamics in Polymer Electrolytes: A Computer Study
Authors: Maitra Arijit , Heuer Andreas 
Published: September 2007

AbstractWe study the segmental dynamics of poly(ethylene oxide) (PEO) from microscopic simulations in the neat polymer and a polymer electrolyte (PEO/LiBF4) by analyzing the normal modes. We verify the applicability of the Rouse theory, specifically for the polymer electrolyte where dynamic heterogeneities, arising from cation–polymer interactions, alter the mobility non‐uniformly along the chains. We find that the Rouse modes for both the systems are orthogonal despite the presence of non‐exponential relaxation of the modes and violation of the Gaussian self‐similarity of the chains. The slowdown of the segmental dynamics in the polymer electrolyte is rationalized by an order of magnitude increase in the friction coefficient for those monomers which are bound by cations. In general, for the electrolyte the Rouse predictions for the dynamics of segments (both free and/or bound) agree well except for very short times.magnified image
A Novel Route for the Preparation of Discrete Nanostructured Carbons from Block Copolymers with Polystyrene Segments
Authors: Huang Jinyu , Tang Chuanbing , Lee Hyungil , Kowalewski Tomasz , Matyjaszewski Krzysztof 
Published: September 2007

AbstractWell‐defined nanostructured carbon was prepared by pyrolysis of core cross‐linked micelles formed from block copolymers containing polystyrene segments. These micelles were obtained by self‐assembly of poly(ethylene oxide)‐block‐polystyrene (PEO113‐b‐PS52) diblock copolymer or brush macromolecules containing polymethacrylate backbone and side chains with PS and poly(acrylic acid) block segments (PBPEM330‐g‐PS40‐b‐PAA111) in selective solvents. UV irradiation was used to induce cross‐linking of the PS core in the micelles. After pyrolysis, the cross‐linked PS cores were converted to a partially graphitic carbon, while the shells were sacrificed, resulting in the formation of discrete carbon nano‐objects. The formation of carbon material was confirmed by Raman scattering spectroscopy while the morphology of the precursor and the resulting pyrolyzed product was studied by atomic force microscope (AFM).magnified image
Room Temperature Bulk Synthesis of Silver Nanocables Wrapped with Polypyrrole
Authors: Nadagouda Mallikarjuna N. , Varma Rajender S. 
Published: September 2007

AbstractWet chemical synthesis of silver cables wrapped with polypyrrole is reported in aqueous media without use of any surfactant/capping agent and/or template. The method employs direct polymerization of pyrrole in an aqueous solution with AgNO3 as an oxidizing agent. The four probe conductivity results for the as‐synthesized silver nanocables of polypyrrole films were found to be 3, 5, 5, and 9 S · cm−1 for a 1: 2, 1: 1, 1: 0.5, and 1: 0.1 silver‐to‐pyrrole ratio, respectively. This approach can be extended to other monomers such as aniline and N‐methylaniline (NMA) to prepare different morphologies of silver nanostructures. Aniline monomer polymerization occurred at room temperature to produce a coating of a silver mirror on the side walls of the glass vial, as in the case of Tollen's process of making silver mirrors. The silver mirror coating strategy was extended to a poly(ethylene terephthalate) (PET) surface and the resistivity of the polyaniline‐coated Ag nanocomposites were measured and found to be semiconducting.magnified image
Spermatozoa modulate epididymal cell proliferation and protein secretion in vitro
Authors: Reyes‐Moreno Carlos , Laflamme Julie , Frenette Gilles , Sirard Marc‐André , Sullivan Robert 
Published: September 2007

AbstractNormal epididymal function, such as protein expression and secretion, is primarily regulated by testicular androgens and temperature. However, the role of spermatozoa in this critical process has never been studied. In order to determine whether sperm itself could regulate epididymal function, we have developed a cell culture system of bovine epididymal cells to study the interactions between spermatozoa and the epididymal epithelium. Primary cells from caput, corpus, and cauda epididymal tissues were cultured in the presence of androgens at 32°C (scrotal) and 37°C (abdominal). Newly synthesized proteins were metabolically labeled with35S‐methionine after sperm co‐incubation and the pattern of secreted proteins was analyzed by two‐dimensional polyacrylamide gel electrophoresis. Proliferation rate, protein secretion rate and electrophoretic patterns of secreted proteins were evaluated 48 hr post‐co‐incubation. Incubation at 32°C indicated that spermatozoa stimulation increases the level of protein secretion of cultured cells from all epididymal sections while it slightly decreases proliferation of corpus cells. At 37°C, spermatozoa co‐incubation significantly decreases the protein secretion rate of cultured cells from all epididymal sections. Independently of cell incubation temperature, spermatozoa stimulation induces both an increase in the intensity of radiolabeled proteins and the appearance of new secreted proteins of caput cells without affecting the protein pattern of corpus or cauda cells. Incubation at 37°C, however, greatly modifies the pattern of proteins expressed at 32°C by cauda cells. Taken together, these results support the hypothesis that spermatozoa themselves affect epididymal cell function, most importantly for caput epididymides. Mol. Reprod. Dev. 75: 512–520, 2008. © 2007 Wiley‐Liss, Inc.