Application of the Tracer Method for Surface Area Measurement

The application of C-14-labelled stearic acid uptake for surface area determination was investigated in the case of 15 different adsorbents.

It was stated, that the stearic acid uptake did not correspond to the surface area values, obtained by the B.E.t. method. Only part of the uptaken stearic acid was physically adsorbed: partly it was linked to the surface chemically. Beacuse of the irreversible character of the adsorption, the stearic acid uptake cannot generally used for surface area determination.     

Use of Phosphoantimonic Acid for Arsenic Determination by Activation Analysi

A methed was elaborated to determine arsenic amount in skin samples by neutron activation analysis and high-resolution gamma spectrometry including sample preparation after mineralization by sorption on silicagel saturated with phosphoantimonic acid. The samples were irradiated in the VVR-S reactor core in a flux of 10¹³ neutrons · cm^?2 · s^?1, mineralized with a mixture of nitric and sulphuric acids, the gamma spectrum was measured after passing through an ion-exchanger containing 0.5 mol P₂O₅ to 1 mol Sb₂O₅ (SP-2) by a gamma-spectroscopy system PLURIMAT 20 with a Ge(Li) detector, and the ⁷⁶As photopeak of E_γ = 0.559 MeV was measured. The values of the results obtained varied in the range of (4?5 )× 10^?1 ppm arsenic. The sensitivity of the proposed determination method is l×10^?3 μg arsenic.     

Enrichment of Lithium,Potassium, Copper,and Uranium Isotopes by Electromigration in a Cation Exchange Membrane

The ion exchange membrane can be used as an effective medium of electromigration for the separation of isotopes by the following reasons.     

Further Development of Automatic Activation Analysis System (AAAS) with Fast Neutrons

Improvement of results of activation analysis has been achieved by using a device for simultaneous rotation of the sample around tow axes: one parallel and the other perpendicular to the target during the irradiation. A change of the construction of the container resulted in the increase of its volume and a decrease in the mean sample-to-target distance. The distribution of the neutron flux along the axis of the container during the irradiation has been measured. An arrangement for automatic loading and unloading of sample is also described.     

An Automatic Activation Analysis System (AAAS) with the Use of Fast Neutron Generator

The described system is designed for automatic activation analysis with 14 MeV neutrons. The automatization comprises all operations and time control of the activation cycle. There is a possibility of independent programming of the irradiation time, the decay timè and seven consecutive measuring periods in large range (3 sec to 80 min) by means of a special time control unit. The dispatch of containers with samples is done with a very simple pneumatic device. The design and effectivity of shieldings against fast neutrons are also described.     

Determination of the Products of Irradiation of Natural Molybenum By Deuterons with Energy up to 13 MeV by Means of Semiconductor Gamma- and X-Ray Spectrometry

Introduction

Among the products of irradiation of natural molýbdenum by deuterons with energies up to 13 MeV, by means γ and X-ray speclrometry were identified these radlonudldes: ⁹⁹Nb, ^92mNb, ^95m+gNb ⁹⁶Nb, ⁹⁹Mo, ¹⁰¹Mo, ⁹²Tc, ^93m+gTc, ^94m+g^>Tc, ^95m+gTc, ⁹⁶Tc, ^97mTc, ^99mTc,¹⁰¹Tc, and ⁸⁹Zr. With the more intensive lines of γ transitions of ⁹⁰Nb, ⁹⁶Nb, ^93m+gTc, ^94m+gTc, ^95m+gTc, ⁹⁹Tc and ^97mTc accurate photon energies have been established and for the lines 1475.7 and 1520.5 keV of ⁹³Tc, 820.2 keV of ^95mTc, and 96.4 keV of ^97mTc also the absolute intensities of the emitted γ were determined. By means of aluminium foils, by which the set of Mo foils had been interlaid, the atomic recoil in forward and backward direction ivas established for the 17.82 mg/cm² Mo foils and deuteron energy up to 12.7 MeV and the ion current of 3.4 μA.     

Substoichiometric Determation of Silver Traces in Palladium with Adsorptive Sampling

A substoichiometic analytical method of high sensitivity combined with adsorptive sampling has been worked out for the determination of traces of silver in palladium making use of the selective deposition of microquantities of silver from aqueous solutions of palladium salts on cathodically polarized platioum surfaces. The stability and reporducibility of the saturation values of deposited silver are practially independent of the content and concentration of silver and palladium in the solution. The sensitivity proved to be 0.01 ppm, the accuracy ± 30 per cent.     

Determination of the D2O Content in Water by Infrared Spectrometry

A method for determining deuterium oxide content in the concentration range of 1 to 100% with a precision of 1 to 0.1 percentage unit is described. Measurements were made with a glass cell 0.6 mm thick using the infrared spectrum region from 4000 to 4400 cm^?1. It was found that glass windows can be also used for absorption cells in the range between 2300 and 3800 cm^?1 in which very intense OD and OH bands appear.     

New observation of the , 1Δg, and 2Πg states and molecular constants with all Li2, Li2, and LiLi data

This paper reports our new observation of the , 1³Δ_g (v = 2–4), and 2³Π_g (v = 2–8) states of ⁶Li⁷Li by continuous wave perturbation facilitated optical–optical double resonance spectroscopy. Combining our new experimental term values of ⁶Li⁷Li with the available experimental data of ⁶Li₂ and ⁷Li₂, molecular constants and potential energy curves by Rydberg–Klein–Rees and direct-potential-fit techniques have been determined. Born-Oppenheimer breakdown parameters of the Li₂ 1³Δ_g and 2³Π_g states are calculated.     

A Sensitive and Precise Method for Estimation of Free Thyroxine in Serum as a Thyroid Function Test Using L-Thyroxine-125I

A method for free thyroxine estimation in serum, using labelled thyroxine and Sephadex G-25 has been developed.

The experiment has been carried out by incubating labelled thyroxine with serum samples and separating the free thyroxine from bound protein in the serum by gel filtration after complete equilibrium between exogenous and endogenous thyroxine. Factors affecting the free thyroxine ratio such as volume of serum used, concentration of labelled thyroxine, time and temperature of incubation were studied and the optimum conditions for the test were selected.

The sensitivity of the technique was determined by carrying out twelve estimations of the free thyroxine ratio on samples of pooled normal serum, pooled hypothyroid serum, and pooled hyperthyroid semm. In addition free thyroxine ratio leas determined for 23 hypothyroidisms, 99 euthyroid patients, 40 untreated thyrotoxicosis and 50 normal serum samples. A good correlation with the thyroid status of the patients (as determined) clinically and with radioiodine techniques was observed.     

Nuclear reactions of C on a liquid hydrogen target measured with the superconducting TOF spectrometer

Reaction cross sections with various kinds of breakup channels for neutron-rich carbon isotopes ^18-20C and for ⁹Be impinging on a liquid hydrogen target were investigated at 40 MeV/nucleon. The nuclides of interest were produced via projectile fragmentation from a 63 MeV/nucleon ⁴⁰Ar beam and were separated in flight at the RIKEN projectile fragment separator (RIPS). The combination of the large-acceptance superconducting TOF spectrometer, TOMBEE (TOF Mass analyzer for exotic BEam Experiment), with a liquid hydrogen target, CRYPTA (CRYogenic ProTon and Alpha target system), enables simultaneous measurements of several reaction channels: the reaction cross sections (σR), individual elemental fragmentation cross sections (σΔZ), charge-changing cross sections (σcc), neutron-removal cross sections (σ−xn), and charge-pickup cross sections (σΔZ+1) for ^19,20C; σΔZ, σ−xn, and σΔZ+1 for ¹⁸C; and σR for ⁹Be. The present σR of ⁹Be on proton, σR=397±23 mb, measured in the inverse kinematics, was consistent with the previous measurements using proton beams at different laboratories. The σR of ¹⁹C and ²⁰C on proton were determined to be σR=754±22 mb and σR=791±34 mb, respectively. Taking into account the beam energy and target dependence of σR, the present σR are found to be considerably enhanced compared with those measured at around 1 GeV/nucleon. The σΔZ+1 appears to increase with the mass number of the projectiles, and it significantly contributes to σR in the present energy range. The finite-range optical-limit and few-body Glauber model analyses were performed for σR to study the nuclear matter density distributions and to derive the relative strength of the s-wave components of the valence neutrons in ¹⁹C and ²⁰C. A neutron halo structure of ¹⁹C is confirmed with an s-wave dominance of the valence neutron when the effect of the charge-pickup reaction is taken into account. The large σ−n of ¹⁹C and σ−2n of ²⁰C also support the decoupled structures of ¹⁸C +n and ¹⁸C+2n, respectively. The σcc of ¹⁹C and ²⁰C agree with each other within their experimental uncertainties, which might indicate a similar proton density distribution in ¹⁹C and ²⁰C. The σΔZ decreases monotonically without the even-odd effect as the number of removed protons increases.     

Part 1: The Principles of the Method

Although the principle of the concentration measurement of the elements having great neutron cross sections, e.g. Li, B, Cd, by the method of thermal neutron flux attenuation is well known, some difficulties are encountered in its practical application. These arise mainly because of the influence of the geometry conditions on the measurement.     

Incorporation of Radioiodine in Thyroid Hormones for the Determination of T3/T4 Ratio Using Paper Chromatography

A precise and accurate method is being developed for the determination of T₃/T₄ ratio. This method depends on using serum of different thyroid cases for the assesment of T₃/T₄ ratio. It has been found that the best temperature of storage is 0.0 °C to 4 °C before extracting the iodinated tyrosines and thyronines.

Iodination with ¹²⁵I was done according to our previous technique to render the separated thyronine radioactive. Scanning method helped for the determination of T₃/T₄ ratio. The results were confirmed by sensitivity and recovery test and statistically analyzed. 100 cases were investigated comprising hypo-, eu-, and hyperthyroid cases.     

Determination of the (Na) Sternheimer antishielding factor by Na NMR spectroscopy on sodium oxide chloride, Na3OCl

The (Na⁺) Sternheimer antishielding factor γ_∞ (Na⁺) was determined by ²³Na NMR spectroscopy on sodium oxide chloride, Na₃OCl. The quadrupolar coupling constant of the sodium ion in Na₃OCl was determined to QCC=11.34 MHz, which presents the largest coupling constant of a sodium nucleus observed so far. Applying a simple point charge model, the largest principal value of the electric field gradient at the sodium site was calculated to V_zz=−6.76762·10²⁰ V/m². From these values we calculated the (Na⁺) Sternheimer antishielding factor to γ_∞ (Na⁺)=−5.36. In sodium oxide, Na₂O, we observed an isotropic chemical shift of δ_CS=55.1 ppm, referenced to 1 M aqueous NaCl (δ=0 ppm).     

On the Development of a Method for Determining the Concentration of Hydrogen in Materials Based on Nuclear Backscattering Spectrometry

Metal hydrides and their alloys are widely used in nuclear power engineering and are regarded as promising hydrogen accumulators. Due to the nature of materials used in reactors, nondestructive methods are required to determine the concentration of hydrogen and its content in hydrides under the influence of a harsh environment. In this paper, a technique based on nuclear backscattering spectrometry is proposed, which allows determination of the hydrogen content in a sample at a depth of up to 100 μm. The profiles of the hydrogen distribution in Al, Mg, Ti, Zr, and their hydrides are measured. Estimation of the radiation damage to the sample is performed using the example of polymer impregnation of the protective coating.     

基于M2因子测量的大气湍流参数的确定方法

基于广义惠更斯-菲涅尔原理以及大气湍流理论,推导出部分相干光束在大气湍流中传输的光束传输M ^{2因子的解析表达式.定量分析了表征大气湍流参数的折射率结构常数 C2_n}和涡旋内尺度 l _{0对 M ^{2因子的影响,并由此提出了一种通过实验测量大气湍流中光束的 M 2因子,进而确定出大气湍流参数的新方法.研究结果表明,由于大气湍流对相干性好的光束影响更为明显,在测量中可采用具有高相干性的基模高斯光束作为测量光源,而测量装 关键词： 2因子')" href="#">光束传输 M 2因子 大气湍流参数 湍流折射率结构常数 湍流涡旋内尺度}}     

Transition prediction for supersonic and hypersonic boundary layers on a cone with angle of attack

Transition prediction for boundary layers has always been one of the urgent problems waiting for a solution for the development of aero-space technology, yet there is no reliable and effective method due to the complexity of the problem. The e ^N method has been regarded as an effective method for the transition prediction of boundary layers. However, it heavily relies on experiment or experience. And in cases with three-dimensional base flow, for instance, the boundary layer on a cone with angle of attack, the result of its application is not satisfactory. The authors have found its cause and proposed the method for its improvement, which did yield the fairly satisfactory result for a given test case, and also did not rely so much on experiment or experience. However, before people can really apply this method to practical problems, more test cases have to be studied. In this paper, more test cases for the application of the improved e ^N method to problems of transition prediction of supersonic and hypersonic boundary layers on cones with angle of attack will be studied. The results are compared with those obtained by experiments and/or direct numerical simulations, confirming that the improved e ^N method is effective and reliable. We also find that there may be more than one ZARF for each meridian plane, and which one should be chosen for the e ^N method has been clarified. Supported by the National Natural Science Foundation of China (Grant Nos. 10632050 and 90716007), the Special Foundation for the Authors of National Excellent Doctoral Dissertations (Grant No. 200328), and the Foundation of Liu-Hui Center of Applied Mathematics of Nankai University and Tianjin University Contributed by ZHOU Heng