[en] Assay conditions for the short-term, radiochemical, in vitro determination of the spontaneous rate of juvenile hormone biosynthesis by isolated corpora allata from Leptinotarsa decemlineata have been further improved permitting the measurement of juvenile hormone biosynthesis by individual pairs of corpora allata. Using the new assay conditions, the activities of adult corpora allata during maturation were found to be significantly higher in reproductive, long-day animals than in pre-diapause, short-day beetles. During diapause no activity was detectable, whereas corpora allata from post-diapause beetles were reactivated totally after 5 days. Simultaneous determination of the in vitro rates of juvenile hormone biosynthesis and corpus allatum volumes revealed no clear correlation. (Auth.)

[en] The views of the Third World that need to be given consideration in international nuclear policy-making are presented in the following topical sections: background summary of developing countries energy needs and sources, incentives for nuclear power development in developing countries, the need for nuclear cooperation, the Non-proliferation Treaty, erosion of confidence of the recipient states in the reliability of international cooperation agreements, and perceptions of the Third World regarding energy and proliferation

[en] We study the commutativity of certain class of rings, namely rings with unity 1 and right s-unital rings under each of the following properties [yx^m - xⁿ f(y)x^p,x]=0, [yx^m+xⁿf(y)x^p,x]=0, where f(t) is a polynomial in t²Z[t] varying with pair of ring elements x,y and m,n,p are fixed non-negative integers. Moreover, the results have been extended to the case when m and n depend on the choice of x and y and the ring satisfies the Chacron's Theorem. (author). 14 refs

[en] To evaluate the feasibility of the material used in nuclear reactor technology, seventy one metal bearing ore samples were collected from various localities of Pakistan. These were analyzed by employing various instrumental analytical techniques such as atomic absorption, visible spectrophotometry, x-ray fluorescence, flame photometry, radiometry and inductively coupled plasma-emission spectrometry 'ICP'. The concentration of uranium, thorium and zirconium were found up to 0.190%, 10.5% and 3.3% respectively. Calcium, magnesium, sodium, potassium, iron, aluminium and silica were the major ore constituents, like manganese, strontium, barium, zinc, hafnium and lead were present at trace levels in the samples. The solvent extraction methods for the extraction of the thorium and zirconium from their ore leached solutions using 30% and 40% (v/v) di-n-butyl sulfoxide (DBSO) in xylene from 2M HNO/sub 3/ and 7M HNO/sub 3/ aqueous solutions have been developed respectively. The stoichiometric compositions of the extracted complexes of thorium and zirconium with DBSO were determined by slope analysis and found to be 1:2 and 1:1 respectively. The process of thorium extraction was found exothermic in the temperature range studies (30-55) deg. C whereas, eligible effect on the extraction of zirconium was noted up to 50 deg. C. Zirconium/sup 95/ radio tracer was used to follow the extraction of zirconium while a spectrophotometric method has been developed and employed for the determination of thorium as chromogenic reagent. Absorbance was measured at 544 nm. The process of thorium extraction was found exothermic. The percent purity for extracted thorium was found to be > 98% whereas, for zirconium it was noted > 96%. The recycling capacity of the organic solvent for thorium and zirconium have been checked and found to be quite satisfactory. On the basis of data obtained at laboratory scale extraction studies, pilot plant schemes for the extraction and the refining of these metals from their ores have been worked out. (Orig./A.B.) 330 refs

[en] In the present paper we first establish the commutativity theorem for semiprime ring satisfying the polynomial identity [xⁿ,y]x^r = ±y^s[x,y^m]y^t for all x,y in R, where m,n,r,s and t are fixed nonnegative integers, and further, we investigate commutativity of rings with unity under some additional hypothesis. Moreover, it is also shown that the above result is true for s-unital. Also, we provide some counter examples which show that the hypothesis of our theorems are not altogether superfluous. The results of this paper generalize some of the well-known commutativity theorems for rings which are right s-unital. (author). 21 refs

No abstract available

[en] Nuclear power is now being accepted as a fully competitive source of electric power in large sized units in many industrialized countries. If we examine growth of nuclear capacity in recent years, we find that there has been a steady increase in unit sizes and this trend is likely to continue. Under these circumstances countries which are unable to use large plants may find it increasingly difficult to benefit from cheap nuclear power until their grids become extensive enough to absorb such large units. This paper examines the prospects of intermediate size power reactors (200 - 500 MW), by reviewing the problems associated with their availability and competitiveness and suggests how some of these problems could be met.

[en] The subject is discussed under the following topics: Energy Needs and Developing Countries; Atoms for Peace Plan and the Golden Era of Cooperation; NPT and the Development of Safeguards; London Suppliers Club and Its Guidelines; Case Histories in Erosion of Confidence; Impact of Forced Renegotiation of Contracts; Non-Proliferation Treaty; Perceptions in the Third World; and Cooperation Between Third World and Advanced Countries

[en] The IAEA is a unique organization within the UN system dealing with the promotion as well as regulation of a new technology to ensure that its increasing use remains both safe and peaceful. It has succeeded to an admirable extent in the performance of such dual functions owing to the co-operation and spirit of consensus demonstrated by the Member States and its pragmatic evolution despite many difficulties over the past four decades. In this brief article, an attempt has been made to identify some of the major milestones and turning points in the growth of the IAEA

[en] Coal fired thermal power plants face serious challenges due to high temperature corrosion of structural materials by oxidation, sulfidation and ash corrosion. The present work is an attempt for corrosion study of stainless steel during the combustion of coal for a length of time. The composition of coal was determined by CHNS-O elemental analyzer and the coal that contained about 50% carbon were selected for corrosion studies of 304-S.S i.e. from Chakwal, Jhelum and Mianwali. The sulfur content of these coals varied from 4 ∼ 8%. In the experiment, ash was prepared from coal in open stainless steel container under excessive oxidation condition. The sulfur content in ash was found to be in the range of 1 ∼ 3% by XRF analysis. 304-S.S samples were engulfed in the ash bed which was placed in porcelain crucible. These samples were kept at 650 degree C for 400 hours. The change in weight after every 100 hour was measured. It was found that coal of Jhelum showed minimum weight change per unit area. The corrosion rate has been calculated 0.3153mpy and proved to be best coal from least material degradation point of view. The film comprised mainly of iron oxide product as detected by XRD analysis. Second experiment was also performed in a sealed S.S container to study the high temperature corrosion behavior of 304-S.S under sulfur content of about 4.76%. In the experiment calculated amount of sulfur was added into ash before sealing of container and kept in Muffle furnace at 650 degree C for 240 hours. The S.S samples exposed to ash with corrosive SO₃ gas were studied by XRD which showed iron oxide as well as iron sulfide peaks. Formation of film by corrosion has been observed from SEM micrographs and corrosion rate has been calculated from the film thickness. It was found corrosion rate of 304-S.S is minimum i.e. 5mpy when ash of Jhelum's coal was fired and maximum corrosion rate of 34mpy was found for Chakwal's coal ash. The ash content of these coal samples was also determined as described by ASTM-D3174. It was found that the coal of Jhelum contained minimum ash i.e. 19% compared to other samples. It is concluded that coal from Jhelum is superior in the given coal samples from Punjab. (author)