Search results for "complex"
showing 10 items of 5889 documents
Multi-class determination of antimicrobials in meat by pressurized liquid extraction and liquid chromatography–tandem mass spectrometry
2008
A multi-residue method using pressurized liquid extraction (PLE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed for determining trace levels of 31 antimicrobials, including beta-lactams, lincosamides, macrolides, quinolones, sulfonamides, tetracyclines, nitroimidazoles and trimethoprim. The extraction method required pre-homogeneization of the meat with EDTA-washed sand and subsequent one-static-cycle extraction for 10 min with 40 ml of water at 1500 psi and 70 degrees C. The effect of operation temperature, pressure, flush volume, and static cycles on PLE performance was studied. Average recoveries ranged from 75 to 99% with relative standard deviations <1…
Bio-metal-organic frameworks for molecular recognition and sorbent extraction of hydrophilic vitamins followed by their determination using HPLC-UV
2020
A bio-metal-organic framework (bio-MOF) derived from the amino acid L-serine has been prepared in bulk form and evaluated as sorbent for the molecular recognition and extraction of B-vitamins. The functional pores of bio-MOF exhibit high amounts of hydroxyl groups jointly directing other supramolecular host-guest interactions thus providing the recognition of B-vitamins in fruit juices and energy drinks. Single-crystal X-ray diffraction studies reveal the specific B-vitamin binding sites and the existence of multiple hydrogen bonds between these target molecules and the framework. It offered unique snapshots to accomplish an efficient capture of these solutes in complex aqueous matrices. Fo…
Immunoassays for pyraclostrobin analysis in processed food products using novel monoclonal antibodies and QuEChERS-based extracts
2013
Strobilurins are a family of synthetic natural-derived pesticides widely used for fungi control in many crops. As part of a larger research project, a collection of monoclonal antibodies to one of the most relevant strobilurins, i.e. pyraclostrobin, has been generated using functionalized haptens with the spacer arm located at different sites. The toxophore aliphatic moiety, as observed with other strobilurins, and the planar aromatic two-ring system characteristic of this molecule were revealed as the best tethering sites for high-affinity monoclonal antibody production. A central derivatization position did not generate a good immune response, but such derivatives were useful as heterolog…
Atomic fluorescence determination of inorganic arsenic in soils after microwave-assisted distillation
2000
Abstract An inexpensive microwave-assisted distillation procedure has been developed for quantitative determination of inorganic arsenic in soils by atomic fluorescence spectrometry (AFS). After reduction of As(V) to its trivalent state with potassium iodide, inorganic arsenic was distilled as AsCl 3 that was finally determined by atomic fluorescence after hydride generation with NaBH 4 in HCl medium. The different parameters that control the distillation: concentration and volume of HCl, time of distillation, sample weight, and oven load, were studied. The methodology developed has a detection limit of 0.015 μg l −1 , which corresponds to a concentration of 0.006 μg of As per gram of soil,…
Pulsed EPR determination of water accessibility to spin-labeled amino acid residues in LHCIIb.
2009
Membrane proteins reside in a structured environment in which some of their residues are accessible to water, some are in contact with alkyl chains of lipid molecules, and some are buried in the protein. Water accessibility of residues may change during folding or function-related structural dynamics. Several techniques based on the combination of pulsed electron paramagnetic resonance (EPR) with site-directed spin labeling can be used to quantify such water accessibility. Accessibility parameters for different residues in major plant light-harvesting complex IIb are determined by electron spin echo envelope modulation spectroscopy in the presence of deuterated water, deuterium contrast in …
Weak and strong recognition by 2-way randomized automata
1997
Languages weakly recognized by a Monte Carlo 2-way finite automaton with n states are proved to be strongly recognized by a Monte Carlo 2-way finite automaton with no(n) states. This improves dramatically over the previously known result by M.Karpinski and R.Verbeek [10] which is also nontrivial since these languages can be nonregular [5]. For tally languages the increase in the number of states is proved to be only polynomial, and these languages are regular.
High spatial resolution analysis of the iron oxidation state in silicate glasses using the electron probe
2018
The iron oxidation state in silicate melts is important for understanding their physical properties, although it is most often used to estimate the oxygen fugacity of magmatic systems. Often high spatial resolution analyses are required, yet the available techniques, such as μrXANES and μMössbauer, require synchrotron access. The flank method is an electron probe technique with the potential to measure Fe oxidation state at high spatial resolution but requires careful method development to reduce errors related to sample damage, especially for hydrous glasses. The intensity ratios derived from measurements on the flanks of FeLα and FeLβ X-rays (FeLβf/FeLαf) over a time interval (time-depend…
The Importance of the Nurse’s Role in the Management of Complex Diabetic Outpatients: It is the Time to Manage Patient’s Multidimensions
2018
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Development of trackable metal-based drugs: new generation of therapeutic agents
2016
International audience; In medicinal chemistry, the aim is not only to conceive ever more efficient molecules, but also to understand their mechanism of action. In very recent years, a new promising strategy was developed to tackle this issue: the conception of trackable therapeutic agents. Metal-based drugs are ideal to exploit this expanding area of research.
Differenza, autonomia, complessità organizzazionale. Dialettica del pensiero complesso in Edgar Morin
2012
"I know that humanity needs politics. That this politics needs anthroposociology. That anthroposociology needs to be linked to the science of nature...". Edgar Morin (1921), the "traveler of complexity", as he himself likes to call himself, proposes to "reorganize our mental system", the "structure of knowledge", precisely starting from the "revelation of the true structure of reality". The philosophical significance of Morin's thought, compared to the scientific approach, can be seen in the fact that it proposes to make the reality of our universe rise to the dignity of ontological principles, concepts elaborated within the gnoseological and epistemological. This research aims to present t…