Crystallization and agglomeration kinetics of nickel ammonium sulphate in an MSMPR crystallizer

Precipitation of nickel ammonium sulphate achieved by mixing solutions of nickel sulphate and ammonium sulphate in a 5 1 MSMPR crystallizer is used to investigate both crystallization and agglomeration kinetics from the steady-state crystal size distribution. An iterative non-linear parameter estimation procedure is used to deduce the kinetic rate parameters in the solution of the agglomeration model suggested by Liao and Hulburt from the data-set obtained by size analysis of the product crystals. The results obtained are correlated in terms of conventional power law kinetic expressions.     

Acoustic emission technique for leak detection in an end shield of a pressurised heavy water reactor

This paper discusses the successful application of the Acoustic Emission Technique (AET) for detection and location of leak paths present on the inaccessible side of an end shield of a Pressurised Heavy Water Reactor (PHWR). The methodology was based on the fact that air and water leak AE signals have different characteristic features. Baseline data was generated from a sound end-shield of a PHWR for characterizing the background noise. A mock up end-shield system with saw cut leak paths was used to verify the validity of the methodology. It was found that air leak signals under pressurisation (as low as 3 psi) could be detected by frequency domain analysis. Signals due to air leaks from various locations of a defective end-shield were acquired and analysed. It was possible to detect and locate leak paths. Presence of detected leak paths were further confirmed by alternate test.     

On liquid motion in a circular cylinder with horizontal axis

Summary The flow pattern of the slosh motion of a homogeneous, nonviscous (inviscid) and incompressible fluid with a free surface, contained in a rigid circular canal, has been dealt with analytically and experimentally. The axis of the canal is perpendicular to the direction of gravity. Considered are transverse (lateral to axis) oscillations of the liquid. The shape of the free liquid surface is determined numerically by means of a simple procedure. Theoretically calculated streamlines (path lines) are found to be in good qualitative agreement with experimentally observed trajectories of small spheres, made of plastic material and immersed in the liquid. The plastic particles and the liquid (water with a solution of salt added) have the same density.     

De nouveaux stannures ternaires de rhodium et d'elements des terres rares: TR1+xRh2Sn4−x, 0 ⩽ x ⩽ 0,5, TR = La - SmNew ternary stannides: TR1+xRh2Sn4−x, 0≦x≦0.5, TR = La - Sm

New ternary stannides are reported: RE_1+xRh₂Sn_4?x, 0 ? x ? 0,5 (RE = La ? Sm). NdRh₂Sn₄ has been characterized by single - crystal X-ray diffraction analysis. Its structure is of a new type with space group Pnma and Z = 4: a = 18,535(3), b = 4,463(1), $\text{c}\text{= 7,229(1)}\text{A}\text{?}$, D_x = 9,16 g.cm^?1, μ(AgKα) = 13,6 mm^?1, F(000) = 1300, R = 0,040 for 496 independent reflexions (R_w = 0,047). One of the tin sites can be partly occupied by rare earths atoms. The structure types of NdRh₂Sn₄ and Y₂Rh₃Sn₅ are closely related. LaRh₂Sn₄ does not exhibit superconductivity above 1.4 K.     

Si/SiGe n-MODFETs on thin SiGe virtual substrates prepared by means of He implantation

Si/SiGe n-type modulation-doped field-effect transistors grown on a very thin strain-relieved Si/sub 0.69/Ge/sub 0.31/ buffer on top of a Si(100) substrate were fabricated and characterized. This novel type of virtual substrate has been created by means of a high dose He ion implantation localized beneath a 95-nm-thick pseudomorphic SiGe layer on Si followed by a strain relaxing annealing step at 850/spl deg/C. The layers were grown by molecular beam epitaxy. Electron mobilities of 1415 cm/sup 2//Vs and 5270 cm/sup 2//Vs were measured at room temperature and 77 K, respectively, at a sheet carrier density of about 3/spl times/10/sup 12//cm/sup 2/. The fabricated transistors with Pt-Schottky gates showed good dc characteristics with a drain current of 330 mA/mm and a transconductance of 200 mS/mm. Cutoff frequencies of f/sub t/=49 GHz and f/sub max/=95 GHz at 100 nm gate length were obtained which are quite close to the figures of merit of a control sample grown on a conventional, thick Si/sub 0.7/Ge/sub 0.3/ buffer.     

Calorimetric determination of the enthalpy change for the binding of methyl orange to poly(vinylpyrrolidone) in aqueous solution

Thermodynamic parameters have been determined for the interaction of methyl orange and poly(vinylpyrrolidone) in aqueous solutions containing tris, tris and hydrochloric acid, or water only. Enthalpy changes were determined by use of a flow microcalorimeter. Free energy changes were calculated from the results of equilbrium dialysis studies. The results are interpreted in terms of the behaviour of poly(vinylpyrrolidone) in these systems. Analysis of data shows that the hydrophobic interactions in the systems are in the order: tris > wateronly > tris-HC1.