Home About us Contact
|
Home About us Contact | ||
|
|
||
Satisfactory Results (satisfactory + result)
Kinds of Satisfactory Results Selected AbstractsThe Electrochemical Properties of Co(TPP), Tetraphenylborate Modified Glassy Carbon Electrode: Application to Dopamine and Uric Acid AnalysisELECTROANALYSIS, Issue 5 2006Yunlong Zeng Abstract We report the combination of the charge repelling property of tetraphenyl-borate (TPB) anion and the electrooxidation catalytic effect of cobalt(II) tetrakisphenylporphyrin (CoTPP) embedded in a sol gel ceramic film to develop a modified glassy carbon electrode (CoTPP-TPB-SGGCE) for the simultaneous determination of dopamine (DA) and uric acid (UA). The optimized CoTPP-TPB-SGGCE shows excellent sensitivity and selectivity for the DA and UA analysis. As high as 2000 fold acceptable tolerance of ascorbic acid (AA) for the determination of trace DA and UA is reached. In the presence of 0.10,mM AA, the linear concentration range for DA is from 6.0×10,8 to 2.5×10,5,M, and the detection limit is 2.0×10,8,M. For UA, the linear concentration range is from 1.0×10,7 to 3.5×10,5,M, and the detection limit is 7.0×10,8,M. Our study has also demonstrated that the novel CoTPP-TPB-SGGCE shows high stability and reliability. For 6.00,,M DA and UA, a total of 12,measurements were taken in one week, and the relative standard deviation is 2.05% and 2.68% respectively. No obvious shift of peak current and peak potential is observed over a three-month lifetime test. The response of the sensor is very quick and response time is approximately 1,s. Satisfactory results are also achieved when the CoTPP-TPB-SGGCEs being used to detect the DA and UA in human urine samples. [source] Analyses of gibberellins in coconut (Cocos nucifera L.) water by partial filling-micellar electrokinetic chromatography-mass spectrometry with reversal of electroosmotic flowELECTROPHORESIS, Issue 10 2008Liya Ge Abstract In this paper, we present the results of simultaneous screening of eight gibberellins (GAs) in coconut (Cocos nucifera L.) water by MEKC directly coupled to ESI-MS detection. During the development of MEKC-MS, partial filling (PF) was used to prevent the micelles from reaching the mass spectrometer as this is detrimental to the MS signal, and a cationic surfactant, cetyltrimethylammonium hydroxide, was added to the electrolyte to reverse the EOF. On the basis of the resolution of the neighboring peaks, different parameters (i.e., the pH and concentration of buffer, surfactant concentrations, length of the injected micellar plug, organic modifier, and applied separation voltage) were optimized to achieve a satisfactory PF-MEKC separation of eight GA standards. Under optimum conditions, a baseline separation of GA standards, including GA1, GA3, GA5, GA6, GA7, GA9, GA12, and GA13, was accomplished within 25,min. Satisfactory results were obtained in terms of precision (RSD of migration time below 0.9%), sensitivity (LODs in the range of 0.8,1.9,,M) and linearity (R2 between 0.981 and 0.997). MS/MS with multiple reaction monitoring (MRM) detection was carried out to obtain sufficient selectivity. PF-MEKC-MS/MS allowed the direct identification and confirmation of the GAs presented in coconut water (CW) sample after SPE, while, the quantitative analysis of GAs was performed by PF-MEKC-MS approach. GA1 and GA3 were successfully detected and quantified in CW. It is anticipated that the current PF-MEKC-MS method can be applicable to analyze GAs in a wide range of biological samples. [source] Omnidirectional circularly polarized slot antenna fed by a cylindrical waveguide in millimeter bandMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 3 2007José Luis Masa-Campos Abstract A circularly polarized slotted array antenna is presented. The array is fed by a circular waveguide propagating the TM01, to properly generate the required polarization. An omnidirectional azimuth radiation pattern is obtained, as well as a ,10°/+30° elevation antenna coverage. Low losses are achieved because of the waveguide feed. The slot array is mechanized over the metallic wall of the circular waveguide. Furthermore, the antenna presents a solid and rigid mechanical structure, which guarantees an optimum and repetitive response in a manufacturing process. A prototype antenna has been designed and measured. Satisfactory results have been obtained. The slotted array takes part from a signal detection system centered in 36.85 GHz. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 638,642, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22207 [source] Development and validation of a gas chromatography/mass spectrometry method for the metabolic profiling of human colon tissueRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 4 2009Mainak Mal In this study, a gas chromatography/mass spectrometry (GC/MS) method was developed and validated for the metabolic profiling of human colon tissue. Each colon tissue sample (20,mg) was ultra-sonicated with 1,mL of a mixture of chloroform/methanol/water in the ratio of 20:50:20 (v/v/v), followed by centrifugation, collection of supernatant, drying, removal of moisture using anhydrous toluene and finally derivatization using N -methyl- N -trifluoroacetamide (MSTFA) with 1% trimethylchlorosilane (TMCS). A volume of 1,µL of the derivatized mixture was injected into the GC/MS system. A total of 53 endogenous metabolites were separated and identified in the GC/MS chromatogram, all of which were selected to evaluate the sample stability and precision of the method. Of the identified endogenous metabolites 19 belonging to diverse chemical classes and covering a wide range of the GC retention times (Rt) were selected to investigate the quantitative linearity of the method. The developed GC/MS method demonstrated good reproducibility with intra- and inter-day precision within relative standard deviation (RSD) of ±15%. The metabolic profiles of the intact tissue were determined to be stable (100,±,15%) for up to 90 days at ,80°C. Satisfactory results were also obtained in the case of other stability-indicating studies such as freeze/thaw cycle stability, bench-top stability and autosampler stability. The developed method showed a good linear response for each of the 19 analytes tested (r2,>,0.99). Our GC/MS metabolic profiling method was successfully applied to discriminate biopsied colorectal cancer (CRC) tissue from their matched normal tissue obtained from six CRC patients using orthogonal partial least-squares discriminant analysis [two latent variables, R2Y,=,0.977 and Q2 (cumulative),=,0.877]. Copyright © 2009 John Wiley & Sons, Ltd. [source] Optimization of Allium sativum Solvent Extraction for the Inhibition of in Vitro Growth of Helicobacter PyloriBIOTECHNOLOGY PROGRESS, Issue 6 2002Pablo Cañizares Helicobacter pylori (Hp) is the bacterium responsible for serious gastric diseases such as ulcers and cancer. The work described here involved the study of the inhibitory power of Allium sativum extracts against the in vitro growth of Hp(Hp ivg). We used purple garlic of the "Las Pedroñeras" variety for this study. The effects of two different extraction methods (Soxhlet, stirred tank extractor) and four solvents with different characteristics (water, acetone, ethanol, and hexane) were investigated in terms of the efficiency of the extraction process. Satisfactory results were obtained in most cases in the activity tests, indicating that different extracts gave rise to good inhibitory activity against Hp ivg. The extracts that showed the highest bacteriostatic activities were selected to evaluate the influence of the most important operation variables on the extraction yield: stirring speed, operation time, garlic conditioning, and garlic storage time. The best results were obtained using ethanol and acetone as solvents in a stirred tank. The inhibitory powers of these extracts were compared to those shown by some commercial antibiotics used in the medical treatment of Hp infections. The results of this study show that garlic extracts produce levels of inhibition similar to those of the commercial materials. These extracts were also tested against other common bacteria, and equally satisfactory results were obtained. The research described here represents an important starting point in the fight against and/or prevention of peptic ulcers, as well as other pathologies associated with Hp infections such us gastric cancer. The extracted material can be used by direct application and involves a simple and economical extraction procedure that avoids isolation or purification techniques. [source] Simultaneous Determination of Dopamine and Ascorbic Acid Using the Nano-Gold Self-Assembled Glassy Carbon ElectrodeELECTROANALYSIS, Issue 10 2009Guangzhi Hu Abstract Electrochemical behavior of dopamine (DA) was investigated at the gold nanoparticles self-assembled glassy carbon electrode (GNP/LC/GCE), which was fabricated by self-assembling gold nanoparticles on the surface of L -cysteine (LC) modified glassy carbon electrode (GCE) via successive cyclic voltammetry (CV). A pair of well-defined redox peaks of DA on the GNP/LC/GCE was obtained at Epa=0.197,V and Epc=0.146,V, respectively. And the peak separation between DA and AA is about 0.2,V, which is enough for simultaneous determination of DA and AA. The peak currents of DA and AA were proportional with their concentrations in the range of 6.0×10,8,8.5×10,5 mol L,1 and 1.0×10,6,2.5×10,3 mol L,1, with the detection limit of 2.0×10,8 mol L,1 and 3.0×10,7 mol L,1 (S/N=3), respectively. The modified electrode exhibits an excellent reproducibility, sensibility and stability for simultaneous determination of DA and AA in human serum with satisfactory result. [source] Efficacy of tropisetron in patients with advanced non-small-cell lung cancer receiving adjuvant chemotherapy with carboplatin and taxanesEUROPEAN JOURNAL OF CANCER CARE, Issue 2 2008N. TSAVARIS md Even though significant progress has been made, chemotherapy-induced emesis remains a challenging problem. Few studies focus on emesis in patients treated with carboplatin and the observation period is limited to the initial 24 h following chemotherapy. Thus, we investigated if tropisetron (T) monotherapy can adequately prevent acute and delayed emesis in non-small-cell lung cancer (NSCLC) patients receiving a moderately emetogenic chemotherapy (MEC) (carboplatin-containing) regimen. Furthermore, we explored the merits of adding dexamethasone (D) or alprazolam (A) to T, especially in the setting of a pre-existing high level of stress. We studied 60 patients with advanced NSCLC receiving carboplatin and taxanes in three consecutive cycles. During the first cycle, patients received 5 mg of T intravenously before chemotherapy and the same dose per os on each of the following 3 days. In the second cycle, T was co-administered with 8 mg of D once a day, while, during the third cycle, T was combined with per os A 0.25 mg every 12 h and continued over the following 3 days. Finally, we evaluated the impact of stress on the anti-emetic response achieved with the previously described regimens. The combination of T + A was superior to T monotherapy and the combination of T + D, regarding the prevention of acute and delayed emesis. Both T + A and T + D combinations led to appetite improvement, while patients receiving T + A experienced sedation more frequently. Interestingly, subgroup analysis revealed that patients without underlying stress obtained no further benefit by the addition of A or D, while both T + A and T + D combinations led to a better anti-emetic response in patients with stress. In conclusion, T monotherapy provides a satisfactory result in controlling nausea and emesis caused by a MEC regimen in patients without stress. However, the addition of D and, mainly, A improves its anti-emetic effect in patients with obvious stress. [source] A comparative study on interpolation methods for controlled cardiac CTINTERNATIONAL JOURNAL OF IMAGING SYSTEMS AND TECHNOLOGY, Issue 2 2007Deepak Bharkhada Abstract Bai et al. recently proposed to acquire random fan-beam/cone-beam projections with a linear/planar detector from a circular scanning locus for controlled cardiac computed tomography (CT). After specifying a uniform acquisition geometry required by FBP (filtration-backprojection), we rebin the random fan-beam/cone-beam data via nearest-neighbor, quadrilateral and triangle-based linear interpolation methods. The fan-beam and parallel-beam FBP algorithms are employed for rebinned fan-beam projections. The FDK (Feldkamp,Davis,Kress) and t-FDK (tent-FDK) methods are employed for rebinned cone-beam data. Also, nonuniform weighting fan-beam/FDK methods are used to reconstruct without rebinning. As a benchmark, the images are reconstructed using uniform weighting fan-beam/FDK method from data collected at the specified uniform grid. To evaluate the different methods, effects of increasing the number of projections and adding Poisson noise are studied. The root mean square error (RMSE) is used to quantify the image quality by numerical tests with the cardiac phantom. Our results show that it is helpful to perform data interpolation for improvements of the image quality in controlled cardiac CT from random projections. Our simulations indicate that triangular interpolation gives the most satisfactory result for improved image quality whereas quadrilateral interpolationgives the best noise performance. © 2007 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 17, 91,98, 2007 [source] Generation of core/shell iron oxide magnetic nanoparticles with polystyrene brushes by atom transfer radical polymerizationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 20 2007I. Garcia Abstract The functionalization of nanoparticle surfaces is required to improve the dispersion of an inorganic material inside an organic matrix. In this work, polystyrene (PS) brushes were grown on the surface of iron oxide magnetic nanoparticles with atom transfer radical polymerization and a grafting-from approach. After polymerization, the magnetic nanoparticles had a graft density of 0.9 PS chains/nm2. A sacrificial initiator was used to obtain a satisfactory result for the control of the polymerization, as its addition had to generate a sufficient concentration of persistent radicals (deactivator). A variety of techniques, such as Fourier transform infrared spectroscopy, thermogravimetric analysis, gel permeation chromatography, water contact-angle measurements, and atomic force microscopy, were used to characterize the nanoparticles. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4744,4750, 2007 [source] Wide-range length metrology by dual-imaging-unit atomic force microscope based on porous aluminaMICROSCOPY RESEARCH AND TECHNIQUE, Issue 3 2004Dongxian Zhang Abstract A new dual-imaging-unit atomic force microscope (DIU-AFM) was developed for wide-range length metrology. In the DIU-AFM, two AFM units were combined, one as a reference unit, and the other a test one. Their probes with Z piezo elements and tips were horizontally set in parallel at the same height to reduce errors due to geometric asymmetry. An XY scanner was attached to an XY block that was able to move in the X direction with a step of about 500 nm. A standard porous alumina film was employed as the reference sample. Both reference sample and test sample were installed at the center of the XY scanner on the same surface and were simultaneously imaged. The two images had the same lateral size, and thus the length of the test sample image could be accurately measured by counting the number of periodic features of the reference one. The XY block together with the XY scanner were next moved in the X direction for about 1.5 ,m and a second pair of reference and test images were obtained by activating the scanner. In this way, a series of pairs of images were acquired and could be spliced into two wide-range reference and test images, respectively. Again, the two spliced images were of the same size and the length of test image was measured based on the reference one. This article presents a discussion about the structure and control of the DIU-AFM system. Some experiments were carried out on the system to demonstrate the method of length calculation and measurement. Experiments show a satisfactory result of wide-range length metrology based on the hexagonal features of the porous alumina with a periodic length of several tens of nanometers. Using this method the DIU-AFM is capable of realizing nanometer-order accuracy length metrology when covering a wide range from micron to several hundreds of microns, or even up to millimeter order. Microsc. Res. Tech. 64:223,227, 2004. © 2004 Wiley-Liss, Inc. [source] Assessment of left ventricular systolic function using tissue Doppler imaging in children after successful repair of aortic coarctationCLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 1 2010Tomasz Florianczyk Summary Aim:, Assessment of left ventricular systolic function in children after the successful repair of aortic coarctation using tissue Doppler imaging (TDI). Methods:, The study group consisted of 32 patients (mean age 12·0 ± 4·2 years) after the aortic coarctation repair. The TDI parameters and the conventional echocardiographic endocardial and midwall indices of the left ventricular systolic function were analysed and compared with the results obtained from 34 healthy children. Results:, The systolic mitral annulus motion velocity, systolic myocardial velocity of the medial segment of the left ventricular septal wall, left ventricular strain and Strain Rate (SR) in the study group were significantly higher than in the control group, respectively: 6·92 ± 0·75 cm s,1 versus 6·45 ± 0·83 cm s,1; 5·82 ± 1·03 cm s,1 versus 5·08 ± 1·11 cm s,1; ,28·67 ± 6·04% versus ,22·53 ± 6·44% and ,3·20 ± 0·76 s,1 versus ,2·39 ± 0·49 s,1. Except midwall shortening fraction the conventional endocardial and midwall echocardiographic indices in the study group were significantly higher in comparison to the healthy controls. The left ventricular systolic meridional fibre stress and end-systolic circumferential wall stress did not differ between the examined groups. There were no differences of the TDI or conventional parameters between hypertensive and normotensive patients. Conclusions:, Left ventricular systolic performance in children after the surgical repair of aortic coarctation reveals tendency to rise in late follow-up despite a satisfactory result after surgery. Higher systolic strain and SR in children treated due to coarctation of the aorta may suggest the increased preserved left ventricular performance despite normalization of afterload. [source] Device Closure of Congenital Ventricular Septal DefectsCONGENITAL HEART DISEASE, Issue 2 2007Karim A. Diab MD ABSTRACT Ventricular septal defect is the most common congenital heart malformation. Surgical closure, when indicated, has been practiced for over 50 years with good results; however, surgical closure is still associated with significant morbidity and mortality. Over the past decade, several occluding devices have been developed that made catheter device closure an attractive alternative to surgery with widely satisfactory results. In this article, a comprehensive review of percutaneous and perventricular (hybrid) device closure of each type of ventricular septal defect is presented. [source] Deep Phenol Peeling and Fat Injection: Treatment Option for Perioral Wrinkles in a Scleroderma PatientDERMATOLOGIC SURGERY, Issue 7 2005Yitzhack Ramon MD Background Scleroderma is characterized by abnormal growth of connective tissue, often manifested with hard and tight skin. The viscous properties of the skin are impaired, and the main histologic changes include a thicker dermis, absence of pilosebaceous units, and a decreased space between collagen bundles. Often these patients have wound healing problems. Objective The objective was to demonstrate a case of scleroderma that had deep phenol perioral peeling and fat injection into the lips. According to our bibliographic search, this is the first report in the English literature of using these modalities in scleroderma patients. Methods A 64-year-old woman suffering from scleroderma for more than 20 years came for improvement of her perioral appearance. We decided to manage her deep perioral wrinkles by deep peeling using the Baker formula and concomitantly to use autologous fat injection to augment her thin lips. Results The healing of our patient after these two interventions was uneventful, and satisfactory results have been obtained. Conclusion Based on our experience, this intervention may be suggested for patients suffering from scleroderma after a detailed explanation of the possible wound healing difficulties is provided to the patients. [source] Wire Scalpel for Surgical Correction of Soft Tissue Contour Defects by Subcutaneous DissectionDERMATOLOGIC SURGERY, Issue 2 2000Marlen A. Sulamanidze MD Background. Increasing demand exists for cosmetic correction of soft tissue contour defects. Treatments include simple tissue augmentation techniques or more complex surgeries with consequent relevant recuperation time for the patient. The search for new simple techniques to correct scars and age-related wrinkles and folds is therefore one of the main goals of cosmetic dermatologic surgery. Objective. To improve the cosmetic outcome of patients suffering from soft tissue contour defects by the use of a novel surgical instrument and technique, subcutaneous dissection by wire scalpel. Methods. Fifty-four patients were treated with the wire scalpel technique with no skin incisions to correct a total of 132 depressed cosmetic defects of the face. Forehead lines, glabellar, nasolabial and oral commissure folds, upper lip wrinkles, and acne scars were treated. A 2-month to 4-year follow-up allowed subjective and photographic evaluation of results. Results. Good or satisfactory results were obtained in 79.7% and 16.6% of the cases, respectively. Minor complications did not change the overall positive outcome of the surgery. Conclusion. Subcutaneous dissection by wire scalpel is a simple, safe, and effective method to improve the contour appearance of patients affected with scars or age-related contour defects. [source] CLINICAL USE OF THE NEWLY DEVELOPED ELECTRONIC RADIAL ULTRASOUND ENDOSCOPEDIGESTIVE ENDOSCOPY, Issue 1 2006Masami Ogawa Background:, Endoscopic ultrasonography (EUS) is widely accepted as a diagnostic tool for bilio-pancreatic and gastrointestinal tract diseases. Recently, an ultrasound endoscope with an electronic radial scan transducer has been developed. To evaluate the clinical usefulness of this system, its image quality, advantages and disadvantages were evaluated. Materials and methods:, Ultrasound endoscope with electronic radial scan transducer and its monitor unit were used. The direction of the imaging plane was similar to that of the mechanical radial models. Color Doppler function and tissue harmonic imaging were feasible by this system. To evaluate this endoscope, we investigated the image quality and distance resolution by in-vitro study using thin papers, and 50 patients were examined by this system. Results:, Comparison with the mechanical radial endoscope GF-UM2000 revealed that the image quality was almost equivalent. However, the ultrasound penetration of the electronic radial scanner was better and more satisfactory with less echoic reduction. In addition, the blood-flow signal could be obtained by using the color Doppler function. In contrast, the diameter of the new endoscope was bigger than the advanced mechanical radial models, the monitor unit was bigger than that of the mechanical radial system, and the operation of this unit was complicated. Conclusion:, A prototype of the ultrasound endoscope with electronic radial scan showed satisfactory results regarding the image quality, ultrasound penetration, and clinical diagnosis. The blood flow could be investigated by using the color Doppler function, which is useful to diagnose lesions and detect involvement of the blood vessels in cancers. [source] Barrett's esophagus: combined treatment using argon plasma coagulation and laparoscopic antireflux surgeryDISEASES OF THE ESOPHAGUS, Issue 4 2003M. Pagani SUMMARY, The treatment of Barrett's esophagus is still controversial. Actually, the only method to prevent the development to cancer is endoscopic surveillance, which ensures good results in terms of long-term survival. An ideal treatment capable of destroying columnar metaplasia, followed by squamous epithelium regeneration could potentially result in a decrease of the incidence of adenocarcinoma. Recently most ablative techniques were used, such as photodynamic therapy, ablation therapy with Nd-YAG laser or argon plasma coagulation and endoscopic mucosal resection. We started a prospective study in January 1998, enrolling 94 patients affected by Barrett's esophagus and candidates for antireflux repair in order to assess the effectiveness and the results of endoscopic coagulation with argon plasma combined with surgery in the treatment of uncomplicated Barrett's esophagus. All patients underwent endoscopic treatment with argon plasma; we observed complete response in 68 patients (72.34%), 27 of them (39.7%) underwent antireflux surgery and the other 41 continued medical therapy. Post-operatively 19 patients (70%) underwent regular surveillance endoscopies and in two cases metaplasia recurred. The final objective of these combined treatments should be the complete eradication of metaplastic mucosa. Our experience was that argon plasma coagulation combined with antireflux surgery or proton pump inhibitor therapy gave satisfactory results, even if follow-up is too short to evaluate the potential evolution of metaplasia to cancer. For this reason, we recommend that this technique should be done only in specialized centres and that these patients continue their endoscopic surveillance program. [source] Empirical estimate of fundamental frequencies and damping for Italian buildingsEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 8 2009Maria Rosaria Gallipoli Abstract The aim of this work is to estimate the fundamental translational frequencies and relative damping of a large number of existing buildings, performing ambient vibration measurements. The first part of the work is devoted to the comparison of the results obtained with microtremor measurements with those obtained from earthquake recordings using four different techniques: horizontal-to-vertical spectral ratio, standard spectral ratio, non-parametric damping analysis (NonPaDAn) and half bandwidth method. We recorded local earthquakes on a five floors reinforced concrete building with a pair of accelerometers located on the ground and on top floor, and then collected microtremors at the same location of the accelerometers. The agreement between the results obtained with microtremors and earthquakes has encouraged extending ambient noise measurements to a large number of buildings. We analysed the data with the above-mentioned methods to obtain the two main translational frequencies in orthogonal directions and their relative damping for 80 buildings in the urban areas of Potenza and Senigallia (Italy). The frequencies determined with different techniques are in good agreement. We do not have the same satisfactory results for the estimates of damping: the NonPaDAn provides estimates that are less dispersed and grouped around values that appear to be more realistic. Finally, we have compared the measured frequencies with other experimental results and theoretical models. Our results confirm, as reported by previous authors, that the theoretical period,height relationships overestimate the experimental data. Copyright © 2008 John Wiley & Sons, Ltd. [source] On the accuracy of simplified methods for the analysis of isolated bridgesEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 3 2001P. Franchin Abstract To foster the use of seismic isolation in structures, existing guidelines strive to formulate design methods which are simple and accessible to non-specialized engineers. On the other hand, not all of the simplifying provisions adopted by the norms can be said to have been adequately tested to provide a consistent level of accuracy. The study attempts, in particular, to elucidate three aspects related to the methods of analysis for linear or linearized isolated bridges on which little or no advice can be found in the norms. The first one is about the way one has to account for the fact that damping matrices of isolated bridges are never of proportional type. The present study demonstrates, through a number of typical applications, that classical modal analysis, using real modes and the diagonal terms of the modal damping matrices, still provide a fully acceptable approximation. The second and third aspects are related to the use of linearization expressions extended to the analysis of hyperstatic bridges. Parametric analyses conducted in the study show that none of the formulas in current use gives satisfactory results for both the displacement and the force responses, a requirement for a reliable design of an isolated bridge. How to use the equivalent linear parameters, and in particular the isolators equivalent damping ratios, in the context of a modal analysis, is treated next. This problem is seldom if ever mentioned in the norms where at most a formula is given for constructing modal damping ratios based on the damping ratios of the isolators. A rational, approximate procedure is discussed in this paper, applicable to all types of structures with non-proportional damping, which in the case of bridges can be shown to reduce to the expression provided in the Japanese bridge design guidelines. Copyright © 2001 John Wiley & Sons, Ltd. [source] A Reality Check for Data SnoopingECONOMETRICA, Issue 5 2000Halbert White Data snooping occurs when a given set of data is used more than once for purposes of inference or model selection. When such data reuse occurs, there is always the possibility that any satisfactory results obtained may simply be due to chance rather than to any merit inherent in the method yielding the results. This problem is practically unavoidable in the analysis of time-series data, as typically only a single history measuring a given phenomenon of interest is available for analysis. It is widely acknowledged by empirical researchers that data snooping is a dangerous practice to be avoided, but in fact it is endemic. The main problem has been a lack of sufficiently simple practical methods capable of assessing the potential dangers of data snooping in a given situation. Our purpose here is to provide such methods by specifying a straightforward procedure for testing the null hypothesis that the best model encountered in a specification search has no predictive superiority over a given benchmark model. This permits data snooping to be undertaken with some degree of confidence that one will not mistake results that could have been generated by chance for genuinely good results. [source] A Glassy Carbon Electrode Modified with Multiwalled Carbon Nanotube/Chitosan Composite as a New Sensor for Simultaneous Determination of Acetaminophen and Mefenamic Acid in Pharmaceutical Preparations and Biological SamplesELECTROANALYSIS, Issue 15 2010Ali Babaei Abstract A new chemically modified electrode is constructed based on multiwalled carbon nanotube/chitosan modified glassy carbon electrode (MWCNTs-CHT/GCE) for simultaneous determination of acetaminophen (ACT) and mefenamic acid (MEF) in aqueous buffered media. The measurements were carried out by application of differential pulse voltammetry (DPV), cyclic voltammetry (CV) and chronoamperometry (CA) methods. Application of DPV method showed that the linear relationship between oxidation peak current and concentration of ACT and MEF were 1,,M to 145,,M, and 4,,M to 200,,M, respectively. The analytical performance of this sensor has been evaluated for detection of ACT and MEF in human serum, human urine and a pharmaceutical preparation with satisfactory results. [source] Electroanalysis of Bisphenol A at a Multiwalled Carbon Nanotubes-gold Nanoparticles Modified Glassy Carbon ElectrodeELECTROANALYSIS, Issue 22 2009Xinman Tu Abstract A sensitive electrochemical method was developed for the determination of bisphenol A (BPA) at a glassy carbon electrode (GCE) modified with a multiwalled carbon nanotubes (MWCNTs)-gold nanoparticles (GNPs) hybrid film, which was prepared based on the electrostatic interaction between positively charged cetyltrimethylammonium bromide (CTAB) and negatively charged MWCNTs and GNPs. The MWCNT-GNPs/GCE exhibited an enhanced electroactivity for BPA oxidation versus unmodified GCE and MWCNTs/GCE. The experimental parameters, including the amounts of modified MWCNTs and GNPs, the pH of the supporting electrolyte, scan rate and accumulation time, were examined and optimized. Under the optimal conditions, the differential pulse voltammetric anodic peak current of BPA was linear with the BPA concentration from 2.0×10,8 to 2×10,5 mol L,1, with a limit of detection of 7.5,nmol L,1. The proposed procedure was applied to determine BPA leached from real plastic samples with satisfactory results. [source] Simultaneous Determination of Nickel and Cadmium by Adsorptive Stripping VoltammetryELECTROANALYSIS, Issue 12 2008B. Gholivand Abstract A sensitive and fast method for the simultaneous determination of trace amounts of nickel and cadmium in real samples has been described using differential pulse adsorptive stripping voltammetry (DPASV) by adsorptive accumulation of the N,N,-bis(salicylaldehydo)4-carboxyphenylenediamine (BSCPDA),complex on the hanging mercury drop electrode (HMDE). As supporting electrolyte 0.02,mol L,1 ammonia buffers containing ligand has been used. Optimal analytical conditions were found to be: BSCPDA concentration of 42,,M, pH,9.6 and adsorption potential at ,50,mV versus Ag/AgCl. With an accumulation time of 20,s, the peaks current are proportional to the concentration of nickel and cadmium over the 1,180, and 0.5,200,ng mL,1 with detection limits of 0.06 and 0.03,ng mL,1 respectively. The sensitivity of method for determination of nickel and cadmium were obtained 0.54 and 0.98,nA mL ng,1, respectively. The procedure was applied to simultaneous determination of nickel and cadmium in some real and synthetic artificial samples with satisfactory results. [source] Differential Pulse Voltammetric Determination of Uric Acid on Carbon-Coated Iron Nanoparticle Modified Glassy Carbon ElectrodesELECTROANALYSIS, Issue 10 2008Shengfu Wang Abstract A carbon-coated iron nanoparticles (CIN, a new style fullerence related nanomaterial) modified glassy carbon electrode (CIN/GCE) has been developed for the determination of uric acid (UA). Electrochemical behaviors of UA on CIN/GCE were explored by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). It was found that the voltammetric response of UA on CIN/GC was enhanced dramatically because of the strong accumulation effect of CIN and the large working area of the CIN/GC electrode. The parameters including the pH of supporting electrolyte, accumulation potential and time, that govern the analytical performance of UA have been studied and optimized. The DPV signal of UA on CIN/GCE increased linearly with its concentration in the range from 5.0×10,7 to 2.0×10,5 M, with a detection limit of 1.5×10,7 M (S/N=3). The CIN/GCE was used for the determination of UA in samples with satisfactory results. The proposed CIN/GCE electrochemical sensing platform holds great promise for simple, rapid, and accurate detection of UA. [source] Disposable Screen-Printed Edge Band Ultramicroelectrodes for the Determination of Trace Amounts of Nitrite IonELECTROANALYSIS, Issue 10 2006Jen-Lin Chang Abstract The application of linear scan voltammetry for sensitive determination of nitrite by using a disposable screen-printed edge band carbon ultramicroelectrode (designated as SPUME) was reported in this study. The measurement with the SPUME can be performed in solutions of low ionic strength, e.g., natural waters, because the ohmic loses are negligible. The limiting oxidation current of nitrite showed a wide linear range up to 3,mM at the SPUME. A relative standard deviation of 2.46% (n=5) for analyzing 5,,M nitrite indicated a detection limit (S/N=3) of 0.38,,M. Real sample analysis of mineral and ground water samples as well as bratwurst food product showed satisfactory results. Since the SPUME is low cost and easy for mass production, the disposable nature further offers to application in diverse field of electroanalytical chemistry. [source] Trace Determination of Chromium by Square-Wave Adsorptive Stripping Voltammetry on Bismuth Film ElectrodesELECTROANALYSIS, Issue 21 2004Eleni Chatzitheodorou Abstract This works reports the use of adsorptive stripping voltammetry (AdSV) for the trace determination of chromium on a rotating-disk bismuth-film electrode (BFE). During the reductive accumulation step, all the chromium species in the sample were reduced to Cr(III) which was complexed with cupferron and the complex was accumulated by adsorption on the surface of a preplated BFE. The stripping step was carried out by using a square-wave (SW) potential-time voltammetric signal. Electrochemical cleaning of the bismuth film was employed, enabling the same bismuth film to be used for a series of measurements in the presence of dissolved oxygen. The experimental variables as well as potential interferences were investigated and the figures of merit of the method were established. Using the selected conditions, the 3, limit of detection for chromium was 100,ng L,1 (for 120,s of preconcentration) and the relative standard deviation was 3.6% at the 2,,g L,1 level (n=8). Finally, the method was applied to the determination of chromium in real samples with satisfactory results. [source] The Electrochemical Behavior of ,-Ketoglutarate at the Hanging Mercury Drop Electrode in Acidic Aqueous Solution and Its Practical Application in Environmental and Biological SamplesELECTROANALYSIS, Issue 12 2004Li Yang Abstract The voltammetric behavior of ,-ketoglutarate (,-KG) at the hanging mercury drop electrode (HMDE) has been investigated in acetate buffer solution. Under the optimum experimental conditions (pH,4.5, 0.2,M NaAc-HAc buffer solution), a sensitive reductive wave of ,-KG was obtained by linear scan voltammetry (LSV) and the peak potential was ,1.18,V (vs. SCE), which was an irreversible adsorption wave. The kinetic parameters of the electrode process were ,=0.3 and ks=0.72,1/s. There was a linear relationship between peak current ip, ,-KG and ,-KG concentration in the range of 2×10,6,8×10,4,M ,-KG. The detection limit was 8×10,7,M and the relative standard deviation was 2.0% (C,-KG=8×10,4,M, n=10). Applications of the reductive wave of ,-KG for practical analysis were addressed as follows: (1) It can be used for the quantitative analysis of ,-KG in biological samples and the results agree well with those obtained from the established ultraviolet spectrophotometric method. (2) Utilizing the complexing effect between ,-KG and aluminum, a linear relationship holds between the decrease of peak current of ,-KG ,ip and the added Al concentration C in the range of 5.0×10,6,2.5×10,4,M. The detection limit was 2.2×10,6,M and the relative standard deviation was 3.1% (C=4×10,5,M, n=10). It was successfully applied to the detection of aluminum in water and synthetic biological samples with satisfactory results, which were consistent with those of ICP-AES. (3) It was also applied to study the effect of AlIII on the glutamate dehydrogenase (GDH) activity in the catalytically reaction of ,-KG+NH+NADH,L -glutamate+NAD++H2O by differential pulse polarography (DPP) technique. By monitoring DPP reductive currents of NAD+ and ,-KG, an elementary important result was found that Al could greatly affect the activity of GDH. This study could be attributed to intrinsic understanding of the aluminum's toxicity in enzyme reaction processes. [source] Measurement of dissociation rate of biomolecular complexes using CEELECTROPHORESIS, Issue 3 2009Peilin Yang Abstract Fluorescence anisotropy (FA), non-equilibrium CE of equilibrium mixtures (NECEEM) and high-speed CE were evaluated for measuring dissociation kinetics of peptide,protein binding systems. Fyn-SH3-SH2, a protein construct consisting of the src homology 2 (SH2) and 3 (SH3) domain of the protein Fyn, and a fluorescein-labeled phosphopeptide were used as a model system. All three methods gave comparable half-life of,53,s for Fyn-SH3-SH2:peptide complex. Achieving satisfactory results by NECEEM required columns over 30,cm long. When using Fyn-SH2-SH3 tagged with glutathione S -transferase (GST) as the binding protein, both FA and NECEEM assays gave evidence of two complexes forming with the peptide, yet neither method allowed accurate measurement of dissociation rates for both complexes because of a lack of resolution. High-speed CE, with a 7,s separation time, enabled separation of both complexes and allowed determination of dissociation rate of both complexes independently. The two complexes had half-lives of 22.0±2.7 and 58.8±6.1,s, respectively. Concentration studies revealed that the GST-Fyn-SH3-SH2 protein formed a dimer so that complexes had binding ratios of 2:1 (protein-to-peptide ratio) and 2:2. Our results demonstrate that although all methods are suitable for 1:1 binding systems, high-speed CE is unique in allowing multiple complexes to be resolved simultaneously. This property allows determination of binding kinetics of complicated systems and makes the technique useful for discovering novel affinity interactions. [source] CE-based noncompetitive immunoassay for immunoglobulin G in bovine colostrum productsELECTROPHORESIS, Issue 21 2007Jin Zhao Abstract A CE-based noncompetitive immunoassay for IgG in bovine colostrum products was established. FITC-labeled protein G (FITC-PrG) was tagged through noncovalent bindings to the Fc region of the mouse monoclonal antibovine IgG (Ab). The FITC-PrG, Ab, and IgG formed a sandwiched immunocomplex FITC-PrG-Ab-IgG under optimal incubation conditions. The immunocomplex was separated and analyzed by CZE with LIF detection in less than 2,min in an uncoated fused-silica capillary. Addition of PEG 20,000 (PEG 20M) in the running buffer significantly suppressed analyte adsorption and thus improved the reproducibility and the resolution. The precision of the method was 5.1% (n,=,7). A linear relationship was established for the IgG concentration in the range of 1,5,mg/L with a linear correlation coefficient (r,=,0.9917). The LOD was 0.1,mg/L (S/N,=,3). The method was successfully applied for the determination of IgG in bovine colostrum products and satisfactory results were achieved. [source] Simultaneous determination of Zr(IV) and Hf(IV) by CE using precolumn complexation with a [PW11O39]7, ligandELECTROPHORESIS, Issue 10 2007Sadayuki Himeno Professor Abstract A CE method was developed for the simultaneous determination of Zr(IV) and Hf(IV) at trace levels. A lacunary Keggin-type [PW11O39]7, ligand reacted quantitatively with a mixture of trace amounts of Zr(IV) and Hf(IV) to form the so-called ternary Keggin-type anions [P(ZrIVW11)O40]5, and [P(HfIVW11)O40]5, in 0.010,M monochloroacetate buffer (pH,2.2). Since both ternary anions possessed different electrophoretic mobilities and high molar absorptivities in the UV region, Zr(IV) and Hf(IV) were determined simultaneously with direct UV detection at 258,nm. Each peak height was linearly dependent on the concentration of Zr(IV) or Hf(IV) in the range of 5.0×10,7,1.0×10,5,M; a detection limit of 2×10,7,M was achieved. The utility of the proposed CE method was demonstrated for the simultaneous determination of Zr(IV) and Hf(IV) in natural water samples with satisfactory results. [source] Comparison of the effectiveness of five extraction methods for Clavibacter michiganensis subsp. sepedonicus and Ralstonia solanacearum from potato tubersEPPO BULLETIN, Issue 2 2001J. Martin In the EU Control Directives, the recommended extraction procedure for testing potatoes for Clavibacter michiganensis subsp. sepedonicus and Ralstonia solanacearum comprises incubation followed by differential centrifugation. This method can be qualified as complex because of the number of different steps required. This study evaluates five different extraction methods for each bacterium from both a technical point of view and for the quality of the results. Results showed that in the case of C. m. sepedonicus the clarification step should be avoided. The incubation/shaking method with three subsamples gives at least as satisfactory results as the official EU procedure. It also has other advantages, facilitating immunofluorescence readings due to the reduced quantity of plant debris, and improving the speed and the reliability of the analysis. [source] | |||||||||||||||||||||||||||||||||||||||||||||||||