Search results for "liquid"
showing 10 items of 4351 documents
HPLC: a tool for the analysis of T-2 toxin and HT-2 toxin in cereals.
1984
An analytical procedure for the determination of trichothecenes in various cereals is described. HPLC was performed with a reversed-phase (C18) column eluted with methanol:water (60:40, v/v). Compounds were detected with a refractive index detector. The elution patterns of free and contaminated samples were compared. The recovery of added T-2 toxin (2 and 5 micrograms/g) in rye and wheat was approximately 80%. The application of this method allows for combined use with other sensitive methods such as mass spectrometry and gas chromatography. The described method is operationally simple, relatively inexpensive, and requires no derivatization.
Characterization of the trimeric, self-recognizing Geodia cydonium lectin I.
1983
A D-galactose-specific lectin I was extracted from the sponge Geodia cydonium and purified by affinity chromatography. The molecular weight of lectin I as determined by high-pressure liquid gel chromatography, was found to be 36500 +/- 1300. Disc gel electrophoresis in the presence and in the absence of sodium dodecyl sulfate showed that lectin I is a trimer composed of three different subunits (Mr: 13800, 13000 and 12200); two of the three subunits are linked by one disulfide bond. Isoelectric focusing gave a pI of 5.6 for the native molecule and a pI of 4.4 and of 7.4 for the subunits. The three subunits carry carbohydrate side chains, composed of D-galactose (94%) and of arabinose (5%). …
Isolation of oligopeptides from the water-soluble extract of goat cheese and their identification by mass spectrometry
2001
A procedure for the separation and identification of small peptides from the water-soluble fraction of a goat cheese was developed. The water-soluble extract was ultrafiltered (1000 Da membrane cutoff), and peptides were isolated by sequential chromatography: size exclusion chromatography (HPLC-grade water), anion exchange chromatography (phosphate buffer gradient), and semipreparative reverse-phase high-performance liquid chromatography (water/acetonitrile gradient). The fractions obtained were analyzed by combined mass spectrometry methods including electrospray ionization, liquid secondary ionization, and tandem mass spectrometry to identify and to confirm the sequences of 28 tri- to oct…
Nortriptyline hydrochloride skin absorption: development of a transdermal patch.
2007
The influence of propylen glycol (PG), ethanol, and oleic acid (OA) on nortriptyline hydrochloride (NTH) penetration through human epidermis was studied in vitro at two different pH values (5.5 and 7.4). The influence of lactic acid and polysorbate 80 was studied for a pH of 5.5. Permeation studies through Heat Separated Epidermis, as well as the enhancing effect of the different vehicles, showed a pH dependency. A pH value of 5.5 in the donor solution decreases significantly the permeability coefficient (Kp) with respect to a pH value of 7.4 (0.011+/-0.004 x 10(-6) versus 0.36+/-0.04 x 10(-6)cm/s). The vehicles showed an increasing enhancement effect in the order: polysorbate 80>ethanol/PG…
High-performance and ion-exchange chromatography and chromatofocusing of the human uterine progesterone receptor: its application to the identificati…
1984
Two independent lines of evidence were used to identify the human uterine progesterone receptor. First, three differently tritiated progestogens (Org 2058, R 5020, progesterone) were used for reversible labelling of the receptor. Secondly, the highly potent affinity label 21-[3H]dehydro Org 2058 was used to label covalently the steroid-specific binding site of the receptor. The labelled cytosols were chromatographed on a Mono Q high-performance anion-exchange column in the absence or presence of a high molar excess of the respective unlabelled competitor steroids. In the case of 21-[3H]dehydro Org 2058, Org 2058 was used as the unlabelled competitor. After elution with a NaCl gradient, the …
The spectra of mixed $^3$He-$^4$He droplets
2005
The diffusion Monte Carlo technique is used to calculate and analyze the excitation spectrum of $^3$He atoms bound to a cluster of $^4$He atoms, by using a previously determined optimum filling of single-fermion orbits with well defined orbital angular momentum $L$, spin $S$ and parity quantum numbers. The study concentrates on the energies and shapes of the three kinds of states for which the fermionic part of the wave function is a single Slater determinant: maximum $L$ or maximum $S$ states within a given orbit, and fully polarized clusters. The picture that emerges is that of systems with strong shell effects whose binding and excitation energies are essentially determined over configur…
Nuclear quantum effects in liquid water from path-integral simulations using anab initioforce-matching approach
2014
We have applied path integral simulations, in combination with new ab initio based water potentials, to investigate nuclear quantum effects in liquid water. Because direct ab initio path integral simulations are computationally expensive, a flexible water model is parameterized by force-matching to density functional theory-based molecular dynamics simulations. The resulting effective potentials provide an inexpensive replacement for direct ab inito molecular dynamics simulations and allow efficient simulation of nuclear quantum effects. Static and dynamic properties of liquid water at ambient conditions are presented and the role of nuclear quantum effects, exchange-correlation functionals…
Ionic liquids in bio-refining : synthesis and applications
2013
Fossil fuel resources are not limitless so alternative renewable recourses are needed to fill the void that inevitably will be created once the supplies of this resource start do dwindle. Biomass has the potential to fill this void. Today only a small part of the world annual production of biomass is utilized by humankind, while the rest is allowed to decay naturally. To utilize this renewable resource in the production of fuel and chemicals, the so called bio-refineries specialized in fractionation and making use of all component of the biomass are needed. Ionic liquids could aid in this task. Ionic liquids (ILs) have shown great potential in the field of biomass processing in general and …