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41.
Maria Kamariotaki Alexandra Karaliota Despina Stabaki Thomas Bakas Spyros P. Perlepes Nick Hadjiliadis 《Transition Metal Chemistry》1994,19(2):241-247
Summary The synthesis and study of a number of new iron(III) complexes of the ligands 3-hydroxy-2(1H)-pyridinone (3,2-opoH), 2,3-dihydroxybenzoic
acid (2,3-dhbH3) and 3,4-dihydroxybenzoic acid (3,4-dhbH3) are described. These complexes have the formulae [Fe(3,2-opo)2Cl]·PrnOH, K[Fe(2,3-dhbH)2(H2O)2], [Fe(2,3-dhb)(H2O)2], K[Fe-(3,4-dhbH)2(H2O)2], [Fe(3,4-dhb)(H2O)2] and K6[Fe(3,4-dhb)3]·3H2O. The complexes were characterized by elemental analyses. X-ray powder patterns, t.g.a./d.t.g. techniques, magnetic susceptibilities
and spectroscopic (u.v.-vis., i.r. and variable-temperature 57Fe-M?ssbauer) studies. Monomeric octahedral structures are assigned for the 1∶2 2,3-dhbH2− complex and the 1:3 3,4-dhb3− compound. Dinuclear and/or oligonuclear structures are tentatively proposed for the remaining complexes in the solid state.
In [FeL(H2O)2] (L3− = 2,3-dhb3− or 3,4-dhb3−), iron(III) appears to be 5-coordinate. Both oxygens of 3,2-opo− participate in coordination, while the dihydroxybenzoato ligands exhibit various coordination modes, depending mainly on
the positions of the hydroxy groups, their anionic charge and the ligand∶metal molar ratio used. 相似文献
42.
Virginie Papadopoulou Meng-Xing Tang Costantino Balestra Robert J. Eckersley Thodoris D. Karapantsios 《Advances in colloid and interface science》2014
Bubbles can form in the body during or after decompression from pressure exposures such as those undergone by scuba divers, astronauts, caisson and tunnel workers. Bubble growth and detachment physics then becomes significant in predicting and controlling the probability of these bubbles causing mechanical problems by blocking vessels, displacing tissues, or inducing an inflammatory cascade if they persist for too long in the body before being dissolved. By contrast to decompression induced bubbles whose site of initial formation and exact composition are debated, there are other instances of bubbles in the bloodstream which are well-defined. Gas emboli unwillingly introduced during surgical procedures and ultrasound microbubbles injected for use as contrast or drug delivery agents are therefore also discussed. After presenting the different ways that bubbles can end up in the human bloodstream, the general mathematical formalism related to the physics of bubble growth and detachment from decompression is reviewed. Bubble behavior in the bloodstream is then discussed, including bubble dissolution in blood, bubble rheology and biological interactions for the different cases of bubble and blood composition considered. 相似文献
43.
Inductively coupled plasma atomic emission spectrometry (ICP-AES) is a powerful, sensitive analytical technique with numerous applications in chemical characterization including that of ancient pottery, mainly due to its multi-element character, and the relatively short time required for the analysis. A critical step in characterization studies of ancient pottery is the selection of a suitable decomposition procedure for the ceramic matrix. The current work presents the results of a comparative study of six decomposition procedures applied on a standard ceramic potsherd reference material, SARM 69. The investigated decomposition procedures included three microwave-assisted decomposition procedures, one wet decomposition (WD) procedure by conventional heating, one combined microwave-assisted and conventional heating WD procedure, and one fusion procedure. Chemical analysis was carried out by ICP-AES. Five major (Si, Al, Fe, Ca, Mg), three minor (Mn, Ba, Ti) and two trace (Cu, Co) elements were determined and compared with their certified values. Quantitation was performed at two different spectral lines for each element and multi-element matrix-matched calibration standards were used. The recovery values for the six decomposition procedures ranged between 75 and 110% with a few notable exceptions. Data were processed statistically in order to evaluate the investigated decomposition procedures in terms of recovery, accuracy and precision, and eventually select the most appropriate one for ancient pottery analysis. 相似文献
44.
Fast screening of trace amounts of the perfluorooctane sulfonate anion (PFOS) in water samples was performed following a simple, fast and efficient sample preparation procedure based on vortex-assisted liquid-liquid microextraction (VALLME) prior to liquid chromatography-mass spectrometry. VALLME initially uses vortex agitation, a mild emulsification procedure to disperse microvolumes of octanol, a low density extractant solvent, in the aqueous sample. Microextraction under equilibrium conditions is thus achieved within few minutes. Subsequently, centrifugation separates the two phases and restores the initial microdrop shape of the octanol acceptor phase, which can be collected and used for liquid chromatography-single quadrupole mass spectrometry analysis. Several experimental parameters were controlled and the optimum conditions found were: 50 μL of octanol as the extractant phase; 20 mL aqueous donor samples (pH=2); a 2 min vortex extraction time with the vortex agitator set at a 2500 rpm rotational speed; no ionic strength adjustment. Centrifugation for 2 min at 3500 rpm yielded separation of the two phases throughout this study. Enhanced extraction efficiencies were observed at low pH which was likely due to enhanced electrostatic interaction between the negatively PFOS molecules and the positively charged octanol/water interface. The effect of pH was reduced in the presence of sodium chloride, likely due to electrical double layer compression. The linear response range for PFOS was from 5 to 500 ng L(-1) (coefficient of determination, r(2), 0.997) and the relative standard deviation for aqueous solutions containing 10 and 500 ng L(-1) PFOS were 7.4% and 6.5%, respectively. The limit of detection was 1.6 ng L(-1) with an enrichment factor of approximately 250. Analysis of spiked tap, river and well water samples revealed that matrix did not affect extraction. 相似文献
45.
Alexandros Katranidis Diaa Atta Ramona Schlesinger Knud H. Nierhaus Theodora Choli‐Papadopoulou Ingo Gregor Michael Gerrits Georg Büldt Jörg Fitter 《Angewandte Chemie (International ed. in English)》2009,48(10):1758-1761
It's not easy being green : Real‐time visualization of labeled ribosomes and de novo synthesized green fluorescent protein molecules using single‐molecule‐sensitive fluorescence microscopy demonstrates that the mutant GFPem is produced with a characteristic time of five minutes. Fluorescence of the fastest GFP molecules appears within one minute (see picture).
46.
Despina Livadiotou Anna Maria Fadel Constantinos A. Tsoleridis Julia Stephanidou-Stephanatou 《Tetrahedron》2012,68(22):4202-4209
The synthesis of a number of novel, fully conjugated, planar pentacyclic 5H-indolo[3′,2′:4,5]pyrido[1,2-a][1,3]benzimidazoles (8) and 11H-pyrido[3″,2″:4′,5′]imidazo[1′,2′:1,6]pyrido[3,4-b]indoles (12) by a one-pot reaction of pyranoindolones with substituted o-phenylenediamines or 2,3-diaminopyridines is described. In the case of 2,3-diaminopyridines the reaction proceeds regioselectively affording only regioisomers 12. Structural assignments of the new compounds as well as complete assignment of 1H and 13C NMR signals were based on the analysis of their 1H and 13C NMR (1D and 2D), IR, MS and elemental analysis data. Plausible mechanisms are proposed. 相似文献
47.
In this paper a formula which is derived in [4, p.273] for a rectilinear congruence Σ is expressed in terms of well-known Σ and its middle envelope. Further motivated by this formula we study some specific congruences. 相似文献
48.
Michelle?Letarte Despina?Voulgaraki Deborah?Hatherley Mildred?Foster-Cuevas Nigel?J?Saunders A?Neil?BarclayEmail author 《BMC biochemistry》2005,6(1):2
Background
Protein microarrays represent an emerging class of proteomic tools to investigate multiple protein-protein interactions in parallel. A sufficient proportion of immobilized proteins must maintain an active conformation and an orientation that allows for the sensitive and specific detection of antibody and ligand binding. In order to establish protein array technology for the characterization of the weak interactions between leukocyte membrane proteins, we selected the human leukocyte membrane protein CD200 (OX2) and its cell surface receptor (hCD200R) as a model system. As antibody-antigen reactions are generally of higher affinity than receptor-ligand binding, we first analyzed the reactivity of monoclonal antibodies (mAb) to normal and mutant forms of immobilized CD200R. 相似文献49.
Maria V. Papadopoulou Shyamaprosad Goswami Andrew D. Hamilton 《Journal of heterocyclic chemistry》1995,32(2):675-681
Open chain podands 2a-c and macrocycles 2d-e have been synthesized as potential candidates for 4-aminopterin recognition and binding, featuring H? bonding characteristics and “stacking interaction” 2e. Preliminary binding studies between 6, 7 , and 8 (simpler analogs of the above 2a-e ) as “bosts” and appropriate “guests”, showed that carbamates 2a and 2e are the most promising receptors for 4-aminopterin binding. 相似文献
50.
Alexiadou DK Ioannou AK Kouidou-Andreou SA Voulgaropoulos AN Girousi ST 《Analytical and bioanalytical chemistry》2008,392(3):533-539
Amplicons corresponding to the GC-rich p53 exon 5 and its analogues, synthesized by substituting 60% of cytosine by 5-methyl-cytosine, or 60% of guanosine by inosine
and GC-poor p53 exon 6 were synthesized and investigated electrochemically, in the presence and absence of proflavine, by differential pulse
voltammetry (DPV). Incorporation of base analogues and the thermal stability of the resulting amplicons were tested in the
presence of a fluorescent probe (Sybr–Green). Peak current at 1.0 V was lower for methylated than for unmethylated PCR amplicons
and was similarly affected by proflavine intercalation. In contrast, considerable peak current differences were observed in
the presence of proflavine for unmodified exon 5 v.s. exon 6 or inosine-containing amplicons. Thermal analysis verified the
expected shifts in melting temperature (T
m) due to the base analogue incorporation and GC-content variations. In conclusion, methylated and unmethylated PCR amplicons
could be distinguished in model DNA systems using differential pulse voltammetry (DPV) and use of proflavine could serve as
an electrochemical probe for identifying different DNA conformations. 相似文献