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Abstract  

A one day representative mixed diet of an adult Korean was collectedfrom the data based on the food intake of 108 healthy subjects between theages 20 and 50. Sampling for the Korean total diet was carried out by usinga market basket study based on the Korean standard food consumption schemereported by the Korean Nutrition Society. Average consumption frequency ofdifferent food items for a one day representative mixed diet of an adult Koreanand the amount of each item to prepare a one day Korean representative totaldiet are surveyed. The analytical methods involve both instrumental and radiochemicalneutron activation techniques developed for the determination of the elementsCs, I, Sr, Th and U in various kinds of food samples. Concentrations of traceelements including 5 important elements for radiological protection, U, Th,Cs, Sr and I in the Korean total diet and the 4 most frequently consumed Koreanfoodstuffs have been analyzed by neutron activation analysis. Detection limitsfor U, Th, Sr and I were improved to ppb levels by radiochemical separationafter neutron irradiation. Five biological NIST reference materials were alsoanalyzed for quality control of the analysis. Seventeen trace elements inthe Korean total diet and four Korean representative foodstuffs were alsoanalyzed quantitatively by instrumental neutron activation analysis.

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Let M be the closed, simply connected, 4-manifold with nonnegative sectional curvature, called a nonnegatively curved 4-manifold, with an effective and isometric Z m-action for a positive integer m ≧ 617. Assume that Z m acts trivially on the homology of M. The goal of this short paper is to prove that if the fixed point set of any nontrivial element of Z m has at most one two-dimensional component, then M is homeomorphic to S 4, #i l=1S 2 × S 2, l = 1, 2, or #j k = 1 ± CP 2, k = 1, 2, 3, 4, 5. The main strategy of this paper is to give an upper bound of the Euler characteristic χ(M) under the homological assumption of a Z m-action as above by using the Lefschetz fixed point formula.

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The thermal behaviors of three pentaerythritol tetranitrate (PETN) base polymer bonded explosives (PBX), Detasheet A (EL506A, red) and Datasheet C (EL506C, yellow-green) that supply by DuPont Co., PBXN-301 were investigated using thermal techniques in this work. The thermal properties of PETN base polymer bonded explosives, such as vacuum thermal stability (VTS), time to ignition, auto-ignition and shelf life of PBX that calculation from Arrhenius equation by the length of time for 5% decomposition were also examined. By comparing the thermal properties, VTS and shelf life of PETN base polymer bonded explosives, the application and storage of Datasheet C (EL506C, yellow-green) should be considered carefully, owing to the ingredients of Datasheet C (EL506 C, yellow-green) containing nitrocellulose. Binders that using in this study seems play no significant effect on the decomposition for polymer bonded explosives, because the decomposition temperature of binders is always higher than that of PETN.

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Integral solutions toy 2=x 3+k, where either thex's or they's, or both, are in arithmetic progression are studied. When both thex's and they's are in arithmetic progression, then this situation is completely solved. One set of solutions where they's formed an arithmetic progression of length 4 had already been constructed. In this paper, we construct infinitely many sets of solutions where there are 4x's in arithmetic progression and we disprove Mohanty's Conjecture [8] by constructing infinitely many sets of solutions where there are 4, 5 and 6y's in arithmetic progression.

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Let L=Po(d/dt)n+P1(d/dt)n−1+...+Pn denote a formally self-adjoint differential expression on an open intervalI=(a, b) (−∞≦a<b≦∞). Here the Pk are complex valued with (n — k) continuous derivatives onI, and P0(t)≠ 0 onI. We discuss integrability of functions which are adjoint to certain fundamental solutions ofLy=λy, and a related consequence.

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Jia and Nathanson [2] give a simple and explicit construction of minimal asymptotic bases of orderh for everyh=2. They constructed minimal asymptotic bases from partition of N by means of powers of 2. In this paper, we extend the results of that paper to asymptotic bases constructed from partitions of N by means ofg-adic representations forg=2. Corollary 3 shows that given partition N=W 0?W 1?...?W h-1 such that eachW i contains infinitely many pairs of consecutive integers we can construct a minimal asymptotic bases of orderh in infinitely many way.

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Abstract  

Wastes containing radioactive materials have been produced ever since ore recovery and processing began; however, such materials did not become of public concern until the large-scale activities involving uranium and thorium ores and nuclear fission during and after World War II. Efforts to provide disposal sites for radioactive wastes, especially those associated with nuclear weapons and nuclear energy, have been largely unsuccessful for the past 40 years or so and are nearing crisis proportions as the new millennium begins — its eventual resolution is believed to require greater reliance on stewardship and a larger governmental presence.

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A (D3C)2O (d6-acetone) target was irradiated with semi-monoenergetic neutrons generated from 9Be(p,n)9B reaction with 20 MeV protons to convert 13C and oxygen nuclides in the target into 14C. With both liquid scintillation counting (LSC) and accelerator mass spectrometry (AMS) we measured the (D3C)2O (d6-acetone) liquid targets, which were combustible and easy to afford CO2 for the AMS measurements. The 14C yield measured by the LSC method turned out to be 80 times larger than that by the AMS method. This large discrepancy may be attributed to the loss of 14C atoms during the sample pretreatment in the AMS method such as combustion and cryogenic trapping of CO2. It means that 14C newly produced by nuclear reactions can exist in various chemical forms, i.e., C3D6O, CO, CO2, hydrocarbons, etc., and a simple sample pretreatment right after production can cause serious isotopic fractionation. Therefore, using the AMS method, extreme caution in sample pretreatment should be exercised when the 14C yield produced immediately by nuclear reaction is measured.

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Abstract  

The purpose of this paper is to give a complete classification of real hypersurfces M in complex space forms M n(c), c≠0 in terms of an η-parallel curvature tensor and a certain commutative condition defined on the distribution T 0={XT x M| Xξ} of M in M n(c).

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Abstract  

A procedure is presented to provide sequential determination of isotopic strontium, thorium, plutonium, uranium, and americium in a single biological sample. The method begins with digestion and dissolution of the sample. Tracers and/or carriers are added to the sample for the purpose of chemical yield monitoring. Strontium is first separated from the actinides and from most of the interfering constituents of the sample by precipitation as carbonates. Strontium isotopes are purified, and 89Sr and 90Sr are measured by gas proportional counting. Actinides are separated and purified by ion exchange chromatography, co-precipitated with neodymium fluoride, filtered, and counted by alpha-particle spectrometry.

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