Usual Conditions (usual + condition)

Distribution by Scientific Domains


Selected Abstracts


Note on the existence and uniqueness of optimum lifting surfaces with reduced tip vorticity

MATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 10 2002
J. A. Sparenberg
In linearized optimization theory, lifting surfaces shed tip vorticity of which the strength has in general infinite square root singularities. Here we impose, besides the usual condition on the force action of the lifting surfaces, also a condition on the strength of their shed vorticity by which it remains bounded. Then the existence of a unique optimum under both conditions is proved. Copyright © 2002 John Wiley & Sons, Ltd. [source]


Urinary fluoride excretion in children drinking fluoridated school milk

INTERNATIONAL JOURNAL OF PAEDIATRIC DENTISTRY, Issue 4 2000
C.E. Ketley
Summary.Objective. To determine fluoride excretion under various conditions of fluoride intake and to estimate the fractional urinary excretion of fluoride in individual children participating in a school milk fluoridation scheme. Design. In the first part of the study, individual urine samples were collected from each of eight 4 to 5-year-old children for a continuous period of 55 h. For each child (n = 8) and for each day (n = 3) the maximum urinary fluoride concentration (p.p.m.F), the maximum fluoride excretion rate (,gF/h) and the total daily fluoride excretion (mg) were calculated. The second part of the study was carried out to determine the 24 h fractional percentage of fluoride excreted following administration of a known dose of fluoride in the absence of other sources. Results. Under usual conditions of fluoride intake (i.e. milk containing 0·5 mg fluoride, customary diet and toothbrushing with fluoride toothpaste) the children's daily fluoride excretion was 0·33 mg. The fractional urinary fluoride excretion of a 0·5-mg fluoride tablet was 30%. Conclusions. It is concluded that the children's mean 24 h fluoride excretion was somewhere between that reported in low fluoride conditions and that reported in optimally fluoridated areas. The fractional urinary fluoride excretion was found to be in agreement with the findings of other workers. [source]


Laser desorption/ionization techniques in the characterization of high molecular weight oil fractions.

JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 9 2006
Part 1: asphaltenes
Abstract The molecular weight distribution of the asphaltene fractions of two types of crude oils from two different Italian fields (samples 1 and 2) was investigated. The analytical tools used to perform these analyses were matrix assisted laser desorption ionization (MALDI) and laser desorption ionization (LDI) mass spectrometry. After observing that the use of the matrix (as well as the addition of Ag+) did not improve the quality of the data compared to that obtained in LDI conditions, all further measurements were performed with the latter technique. Operating under usual conditions of laser power and delay time, a very low resolution was observed, showing only macroscopic differences between the two samples in the molecular weight distribution of the different components. An accurate study on the possible reasons of this undesirable behavior indicates that it can originate from space charge phenomena occurring either in the ion source region or during the flight. A valid parameterization of the delay time and the laser power allowed higher quality spectra to be obtained. Surface-enhanced laser desorption ionization (SELDI) measurements were also performed using normal phase (silica) as the sample holder surface. Under these conditions, better results are obtained, proving that the sample,surface interaction is important to achieve, by means of laser irradiation, a homogeneous set of product ions. Both asphaltene samples were fractionated in five subfractions by gel-permeation chromatography (GPC) to obtain a better separation of the molecular weight distributions; the related spectra confirmed these findings. By using different approaches, relevant and reproducible differences between the asphaltene fractions of the two oil samples were observed. Copyright © 2006 John Wiley & Sons, Ltd. [source]


An Evaluation of a Polyethersulfone Hollow Fiber Plasma Separator by Animal Experiment

ARTIFICIAL ORGANS, Issue 1 2001
Zhao Chang-sheng
Abstract: Membrane plasma separators are being used routinely for therapy in various diseases. In this study, a newly developed plasma separator made of polyethersulfone (PES) hollow fibers was evaluated for its plasma filtration efficiency and blood compatibility by animal experiment. Hemolysis did not occur under the usual conditions of plasma separation. The sieving coefficients of total protein and albumin were over 95%, and the total cholesterol was over 90% throughout the perfusions. Decreases in white blood cells, platelets, fibrinogen, and coagulation factors were observed during the early stage of plasma separation, but appear to be within acceptable ranges for clinical use. [source]