Search results for "Molar"
showing 10 items of 1069 documents
Fractal Dimension of Transdermal-Delivery Drug Models: 4-Alkylanilines
2008
Abstract The pathways that exist in porous membranes used to deliver drugs form fractal percolating paths. For a homologous series of 4-alkylanilines, the fractal dimension D is calculated as a model for transdermal-delivery drugs. Program TOPO is used for the calculation of the solvent-accessible surface AS, which is denoted by the centre of a probe, which is allowed to roll on the outside while maintaining contact with the bare molecular surface S. AS depends on the probe radius R. For 4-alkylanilines, the quadrupole moment Θ is doubled. The hydrophobic contribution to AS is doubled while its hydrophilic part remains constant. D increases 11%. Geometric descriptor and topological index re…
Optimization of Labeling PSMAHBED with Ethanol-Postprocessed 68Ga and Its Quality Control Systems
2017
Radiolabeling of the prostate-specific membrane antigen (PSMA) inhibitor Glu-NH-CO-NH-Lys(Ahx) using the 68Ga chelator HBED-CC (PSMAHBED) allows imaging of prostate cancer lesions because of high expression of PSMA in prostate carcinoma cells and in bone metastases and lymph nodes related to the disease. The aim of this work was to optimize labeling of 68Ga-PSMAHBED using the efficient cation-exchange postprocessing of 68Ga as well as the development of a thin-layer chromatography (TLC)-based quality control system. Methods: Labeling was optimized for online ethanol-postprocessed 68Ga eluate investigating various parameters, such as buffer molarity (0.1-1 M), temperature (25°C-90°C), tracer…
Capillary electrophoresis for analyzing pesticides in fruits and vegetables using solid-phase extraction and stir-bar sorptive extraction.
2005
Two procedures based on solid-phase extraction (SPE) and stir-bar sorptive extraction (SBSE) in combination with micellar electrokinetic chromatography (MEKC)--diode array detection (DAD) were compared for the simultaneous extraction of acrinathrin, bitertanol, cyproconazole, fludioxonil, flutriafol, myclobutanil, pyriproxyfen, and tebuconazole in lettuce, tomato, grape, and strawberry. Selectivity and resolution of the MEKC procedure were studied changing the pH and the molarity of the buffer, the type and the concentration of surfactant, and the methanol content in the mobile phase. A buffer consisting of 6 mM sodium tetraborate decahydrate with 75 mM of cholic acid sodium solution (pH 9.…
MALDI-TOF characterization of macromonomers
1996
Methacryloyl endfunctionalized oligostyrene macromonomers were characterized by matrix assisted laser desorption ionization/time of flight (MALDI-TOF) spectroscopy and by isocratic and gradient high performance liquid chromatography (HPLC). The molar mass distribution derived by the different techniques coincide for the investigated oligomers. Mixing experiments revealed that the MALDI-TOF peak areas do not necessarily represent the mixing ratio of the components. Combination of gradient HPLC and MALDI-TOF has resolved the chemical composition of the coupling products formed by reaction of the living anion with oxygen.
Large scale fractionation of pullulan and dextran
2006
Abstract A recently developed large scale fractionation technique named continuous spin fractionation (CSF) was applied to fractionate pullulan and dextran. 450 g of pullulan with a broad molecular weight distribution were fractionated using water as solvent and acetone as precipitant. In this study, we have in five CSF runs prepared three fractions with apparent M ¯ w * values ranging from 17.6 to 413 kg mol−1. Seventy grams of dextran were fractionated with a mixed solvent of water plus methanol. Five fractionation steps resulted in four samples with M ¯ w values between 4.36 and 18.2 kg mol−1.
Entrapment of A Beta 1-40 peptide in unstructured aggregates
2012
Recognizing the complexity of the fibrillogenesis process provides a solid ground for the development of therapeutic strategies aimed at preventing or inhibiting protein-protein aggregation. Under this perspective, it is meaningful to identify the possible aggregation pathways and their relative products. We found that Aβ-peptide dissolved in a pH 7.4 solution at small peptide concentration and low ionic strength forms globular aggregates without typical amyloid β-conformation. ThT binding kinetics was used to monitor aggregate formation. Circular dichroism spectroscopy, AFM imaging, static and dynamic light scattering were used for structural and morphological characterization of the aggre…
Influence of pH on the benzodiazepine-human serum albumin complex. Circular dichroism studies.
1974
The influence of pH on the binding of benzodiazepine derivatives to HSA was studied by circular dichroism measurements and by gel filtration. The binding of nearly all benzodiazepines is increased by rising the pH from 6.60 to 8.20. For flurazepam, clonazepam, and nitrazepam this increase in binding is due to an increase of the affinities, while for the other substances the affinity remains constant and the number of binding sites is increased from one to two. The changes in binding of the benzodiazepines by rising the pH are explained by a cationic amino acid residue near or at the benzodiazepine binding site of the HSA molecule. This second binding site is not detectable by circular dichr…
Influence of smoking upon the postoperative course of lower third molar surgery
2006
Our objective was to determine whether smoking influences the postoperative course (pain and trismus) of lower third molar surgery, with a clinical evaluation of surgical wound condition and analysis of the possible differences between smokers and nonsmokers. The study subjects were randomly distributed into two groups (smokers and nonsmokers) and subjected to lower third molar extraction in the Unit of Oral and Maxillofacial Surgery (Madrid Complutense University, Spain). The study variables were trismus after 7 days, the intensity of pain and the need for rescue medication during a period of one week. The surgical wound was also assessed (color, presence of plaque, etc.). Two cases of pos…
Modelling the influence of nanoparticles in the phase behaviour of an epoxy/polystyrene mixture
2007
Abstract The cloud point temperatures of four series of epoxy/polystyrene blends have been experimentally determined as a function of polymer mass and system composition. The phase diagrams show an UCST behaviour, increasing incompatibility as the molar mass increases. The Flory–Huggins theory with a concentration-dependent interaction parameter has been developed to study the compatibility of two polymers in presence of spherical nanoparticles. This theory has been first compared with the experimental cloud point curve in absence of nanoparticles, and secondly it has been used to predict the thermodynamic behaviour in presence of different volume fraction of nanoparticles. Nanoparticles co…
On the Role of Drop Break Up for Coalescence Processes and Morphology Development in Polymer Blends under Shear
2005
Drop sizes and drop-size distributions were determined as a function of time at constant shear rates, γ, by means of an optical shear cell in combination with an optical light microscope after preshearing the samples at high γ. The systems under investigation were PIB 3/PDMS 152 (PIB: polyisobutylene, PDMS: poly(dimethylsiloxane), numbers: average molar masses in kg/mol) and COP 26*/PDMS 48 (COP: poly(dimethyl-co-methylphenylsiloxane), asterisk: apparent molar mass); all measurements refer to 25 °C. Systems and conditions were chosen such that shear rates in the vicinity of the intersection of the coalescence and the break up curves become experimentally accessible. Under these conditi…