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71.
Tsiafoulis CG Exarchou V Tziova PP Bairaktari E Gerothanassis IP Troganis AN 《Analytical and bioanalytical chemistry》2011,399(6):2285-2294
The rapid and accurate determination of specific metabolites present in biofluids is a very demanding task which is essential
in both medicine and chemistry. l-carnitine (3-hydroxy-4-N-trimethylammonium butyrate) is an important metabolite which participates in a series of biological paths and therefore its
determination is of diagnostic importance. A single quantum coherence filtering 1H NMR methodology was used for the accurate and rapid determination of l-carnitine in human serum samples. The methodology is based on spectral simplification, and specifically on the distinction
of the N-methyl proton signal of l-carnitine that is greatly overlapped in the 1H-NMR spectrum of serum. The quantitative results provided by the proposed method are in excellent agreement with those obtained
by the enzymatic method, which is widely used. The proposed method is rapid (~20 min of experimental time), selective, sensitive,
and has good analytical characteristics (accuracy, reproducibility). Selected protein precipitation methods were also investigated
and sample pretreatment with EtOH is suggested. 相似文献
72.
In this work, is given the Combined Standard Uncertainty (CSU) calculation procedure, which can be applied in spectrophotometric measurements. For the assessment of the computations, different approaches are discussed, such as the contribution to the Combined Standard Uncertainty of the reproducibility, the repeatability, the total bias, the calibration curve, and the type of the measurand. Results of inter-laboratory measurements confirmed the assumptions. For the minimization of the errors propagation a controlled experimental procedure was applied by this laboratory, called “errors propagation break-up” (ERBs). The uncertainty of sample concentration from a reference curve dominates the Combined Standard Uncertainty. The contribution of the method and the laboratory bias (total bias) to the CSU is insignificant under controlled conditions of a measurement. This work develops a simple methodology that can be utilized to evaluate the uncertainty and errors control on routine methods used both by academic researchers or the industrial sector. 相似文献
73.
Oberacher H Pitterl F Siapi E Steele BR Letzel T Grosse S Poschner B Tagliaro F Gottardo R Chacko SA Josephs JL 《Journal of mass spectrometry : JMS》2012,47(2):263-270
Mass spectral libraries represent versatile tools for the identification of small bioorganic molecules. Libraries based on electron impact spectra are rated robust and transferable. Tandem mass spectral libraries are often considered to work properly only on the instrument that has been used to build the library. An exception from that rule is the 'Wiley Registry of Tandem Mass Spectral Data, MSforID'. In various studies with data sets from different kinds of tandem mass spectrometric instruments, the outstanding sensitivity and robustness of this tandem mass spectral library search approach was demonstrated. The instrumental platforms tested, however, mainly included various tandem-in-space instruments. Herein, the results of a multicenter study with a focus on upfront and tandem-in-time fragmentation are presented. Five laboratories participated and provided fragment ion mass spectra from the following types of mass spectrometers: time-of-flight (TOF), quadrupole-hexapole-TOF, linear ion trap (LIT), 3-D ion trap and LIT-Orbitrap. A total number of 1231 fragment ion mass spectra were collected from 20 test compounds (amiloride, buphenin, cinchocaine, cyclizine, desipramine, dihydroergotamine, dyxirazine, dosulepin, ergotamine, ethambutol, etofylline, mefruside, metoclopramide, phenazone, phentermine, phenytoin, sulfamethoxazole, sulfamoxole, sulthiame and tetracycline) on seven electrospray ionization instruments using 18 different instrumental configurations for fragmentation. For 1222 spectra (99.3%), the correct compound was retrieved as the best matching compound. Classified matches (matches with 'relative average match probability' >40.0) were obtained for 1207 spectra (98.1%). This high percentage of correct identifications clearly supports the hypothesis that the tandem mass spectral library approach tested is a robust and universal identification tool. 相似文献
74.
75.
Rosario M. P. Colodrero Aurelio Cabeza Dr. Pascual Olivera‐Pastor Dr. Antonia Infantes‐Molina Dr. Eleni Barouda Konstantinos D. Demadis Prof. Miguel A. G. Aranda Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(27):6612-6618
Breathe easy : Reversible H2O and NH3 gas uptake by 2D calcium tetraphosphonates (see figure) is accompanied by framework structural changes similar to those previously reported for some carboxylate‐based hybrids. This breathing mechanism is accompanied by a volume increase of 55 %, while maintaining the topology and crystallinity of the material.
76.
George Z. Kyzas Eleni A. Deliyanni Kostas A. Matis Nikolaos K. Lazaridis Dimitrios N. Bikiaris Athanasios C. Mitropoulos 《Composite Interfaces》2018,25(5-7):415-454
AbstractBiomedicine and pharmacy identify highly important scientific fields within the present time. However, increased advancements in these sciences have influenced the identification of increased levels in environmental degradation through pollution. Pharmaceutical production has influenced increased scientific and public concern regarding the increasing rate of pollution attributed to high levels of toxicological properties within the products. Pharmaceutical compounds are not fully removed through the integration of wastewater treatment plants (WWTP). This renders pharmaceutical compounds, municipal effluents together with hospitals as the major culprits in the development of the majority of the sources that enhance environmental degradation. A wide range of the compounds have been the identified within WWTP effluents, surface water together with ground and drinking water on a global scale. All above has influenced the research development in technological field developing new ways for efficient removal of pharmaceuticals from wastewater produced from the pharmaceuticals or biomedical industries. This situation may be altered through the utilization of adsorbents. Therefore more studies have been published investigating the use of nanocomposite biomaterials for removing the pharmaceutical compounds existing in biomedical effluents. 相似文献
77.
The axisymmetric and plane extrusion flows of a liquid foam are simulated assuming that the foam is a homogeneous compressible
Newtonian fluid that slips along the walls. Compressibility effects are investigated using both a linear and an exponential
equation of state. The numerical results confirm previous reports that the swelling of the extrudate decreases initially as
the compressibility of the fluid is increased and then increases considerably. The latter increase is sharper in the case
of the exponential equation of state. In the case of non-zero inertia, high compressibility was found to lead to a contraction
of the extrudate after the initial expansion, similar to that observed experimentally with liquid foams and to decaying oscillations
of the extrudate surface. The time-dependent calculations show that the oscillatory steady-state solutions are stable. These
steady-state oscillatory solutions are not affected by the length of the extrudate region nor by the boundary condition along
the wall. 相似文献
78.
Liatsou Ioanna Christodoulou Eleni Pashalidis Ioannis 《Journal of Radioanalytical and Nuclear Chemistry》2018,317(2):1065-1070
Journal of Radioanalytical and Nuclear Chemistry - The present study deals with the preparation of oxidized biochar fibres derived from Luffa cylindrica sponges and the subsequent adsorption of... 相似文献
79.
Eleni Hadjiconstantinou Nicos Christofides Aristide Mingozzi 《Annals of Operations Research》1995,61(1):21-43
We consider the basic Vehicle Routing Problem (VRP) in which a fleet ofM identical vehicles stationed at a central depot is to be optimally routed to supply customers with known demands subject only to vehicle capacity constraints. In this paper, we present an exact algorithm for solving the VRP that uses lower bounds obtained from a combination of two relaxations of the original problem which are based on the computation ofq-paths andk-shortest paths. A set of reduction tests derived from the computation of these bounds is applied to reduce the size of the problem and to improve the quality of the bounds. The resulting lower bounds are then embedded into a tree-search procedure to solve the problem optimally. Computational results are presented for a number of problems taken from the literature. The results demonstrate the effectiveness of the proposed method in solving problems involving up to about 50 customers and in providing tight lower bounds for problems up to about 150 customers. 相似文献
80.
Andreadou I Tsantili-Kakoulidou A Spyropoulou E Siatra T 《Chemical & pharmaceutical bulletin》2003,51(10):1128-1131
We have previously reported on the synthesis of novel indole derivatives containing an amine-triazole moiety (1a-d, 2a-c), and their antioxidant activity on in vitro non-enzymatic rat hepatic microsomal lipid peroxidation. Some of the compounds showed protective activity against oxidative injury of ischemic myocardium. In the present paper we investigated the interactions of these derivatives with reactive oxygen species, in order to find a mechanism of their antioxidant capacity and to identify structural characteristics responsible for these properties. These interactions were compared with melatonin, which is also an indole derivative. The antioxidant profiles of the compounds were established by different in vitro protocols as follows: 1) by the interaction of the compounds with the 1,1-diphenyl-2-picrylhydrazyl (DPPH) stable free radical, 2) their scavenging effects on superoxide anions using an enzymic system of xanthine-xanthine oxidase, 3) their inhibitory effects on xanthine oxidase and 4) their ability to scavenge hydroxyl radicals by comparison with dimethyl sulfoxide (DMSO) for *OH. All compounds were found to interact with DPPH, most of them to be superoxide anion scavengers and to be strong hydroxyl radical scavengers. Derivatives 1a and 1d substituted on the nitrogen of the indolic nucleus were found to have better antioxidant properties than the reference compounds used and melatonin. 相似文献