Mössbauer studies of iron-bearing minerals in coal and coal ash

⁵⁷Fe Mössbauer spectroscopy has been used to characterize the iron-bearing minerals present in some British Columbia coals. The minerals observed in a range of samples include pyrite/marcasite, siderite, jarosite, rozenite or melanterite, and Fe²⁺ -bearing clay minerals such as illite. The presence of jarosite is confirmed through the magnetic hyperfine interaction observed at 4.2 K. The absence of magnetic ordering at 4.2 K for the ferrous sulphate component indicates the presence of rozenite, FeS0₄ · 4H₂0, or melanterite, FeS0₄ · 7H₂0, rather than szomolnokite, FeS0₄ · H₂0 or FeS0₄. The effects of ashing on two of the coals is also studied.     

Electrical transport properties of polycrystalline HgTe films grown from mercury-rich HgTe

Measurements of the Hall coefficient and the d.c. conductivity were made on polycrystalline films prepared from mercury-rich HgTe. It was found that, in addition to grain boundary potential barrier scattering, the contribution of ionized impurity scattering is also quite significant. The effect of excess mercury in HgTe is to increase the mobility and to reduce compensating effects.     

Characterization of information improvement due to N revisions and its generalization by a functional equation

The idea of information improvement was introduced by Thiel [3]. This idea was further extended by the first author to information improvement due to 2 and N revisions and specifically states that different experimenters (a finite number) are required to proceed with given distributions P and U and are permitted to choose a suitable revision. We attempted to provide a measure of information corresponding to Theil's measure which reflected the effect of all revisions. In this paper, the authors have studied a joint characterization of information improvement of N revisions and its generalization by considering a suitable functional equation.     

Some statistical inferences regarding population diversity in terms of the hypoentropy measure

We consider a measure of the diversity of a population based on the λ-measure of hypoentropy introduced by Ferreri (1980). Our purpose is to study its asymptotic distribution for testing hypotheses. A numerical example based on real data is given. This work was partially supported by the Dirección General de Investigación Cientifica y Técnica (DGICYT) under the contract PS89-0019.     

Ultrasonic study of silver nanoparticles for various applications

ABSTRACT

Acoustic properties of aqueous solution of AgNO₃ at various concentrations, in presence of Tannic Acid at a fixed concentration (1 × 10^?4 M/L) are studied by ultrasonic method. Tannic acid, a compound derived from plant extracts, is used as the reducing and stabilizing agent to synthesize Ag-NPs and also enables variation of the mean size of Ag-NPs by taking a suitable concentration ratio of AgNO₃ and Tannic acid in distilled water. Ag-NPs are synthesized at room temperature and further stabilized with the aid of sonication. The temperature dependence of acoustic properties is studied and discussed in this paper. Acoustic properties were measured using multi-frequency nano fluid interferometer. It is found that there is a systematic increase in ultrasonic velocity upto 60 ^oC for almost all the concentrations studied and thereafter its value decreases, while this velocity decreases with increasing concentration of AgNO₃ in solution at higher concentrations only. This study is important to find optimum concentration required for a particular application. The present result will be useful as data for various applications.     

Phosphorylation of activation functions AF-1 and AF-2 of RAR alpha and RAR gamma is indispensable for differentiation of F9 cells upon retinoic acid and cAMP treatment

The role of RAR alpha 1 and RAR gamma 2 AF-1 and AF-2 activation functions and of their phosphorylation was investigated during RA-induced primitive and parietal differentiation of F9 cells. We found that: (i) primitive endodermal differentiation requires RAR gamma 2, whereas parietal endodermal differentiation requires both RAR gamma 2 and RAR alpha 1, and in all cases AF-1 and AF-2 must synergize; (ii) primitive endodermal differentiation requires the proline-directed kinase site of RAR gamma 2-AF-1, whereas parietal endodermal differentiation additionally requires that of RAR alpha 1-AF-1; (iii) the cAMP-induced parietal endodermal differentiation also requires the protein kinase A site of RAR alpha-AF-2, but not that of RAR gamma; and (iv) the AF-1-AF-2 synergism and AF-1 phosphorylation site requirements for RA-responsive gene induction are promoter context-dependent. Thus, AF-1 and AF-2 of distinct RARs exert specific cellular and molecular functions in a cell-autonomous system mimicking physiological situations, and their phosphorylation by kinases belonging to two main signalling pathways is required to enable RARs to transduce the RA signal during F9 cell differentiation.     

Prospects for gene therapy in human prostate cancer

Prostate cancer is the most common neoplasm in men and a significant cause of mortality in affected patients. Despite significant advances, current methods of treatment are effective only in the absence of metastatic disease. Gene therapy offers a renewed hope of using the differential characteristics of normal and malignant tissue in constructing treatment strategies. Several clinical trials in prostate cancer gene therapy are currently under way, using immunomodulatory genes, anti-oncogenes, tumor suppressor genes and suicide genes. A continued understanding of the etiological mechanisms involved in the establishment and progression of prostate cancer, along with advances in gene therapy technology, should make gene therapy for prostate cancer therapeutically valuable in the future.     

On the information improvement due to 2 and N revisions

The idea of information improvement was introduced by Theil in 1967. This idea is further extended in this paper to information improvement due to 2 and N revisions. These measures are characterized by a generalized functional equation. Some related properties of information improvement due to N revisions are also mentioned.     

Comparative study of the profit of a two server system including patience time and instruction time

The paper is concerned with two unit cold standby systems having one regular repairman and one expert repairman. The expert is called only if the regular repairman is not able to complete the repair within some toletable (patience) time. In model 1, it is assumed that an expert, on his arrival, gives instructions to the regular repairman for completing the repair, in model 2, it is assumed that the expert himselg takes over the system and the regular repairman leaves the repair in the presence of the expert. In model 3, there is no provision of calling the expert. Techniques of the semi-Markov processes and regenerative processes are used to obtain various measures of system effectiveness and profit incurred. A pairwise comparison of model 1 is made with model 2 and model 3 through graphs.