Growth and characterization of NLO based L-arginine maleate dihydrate single crystal.
Single crystals of L-arginine maleate dihydrate (LAMD) were successfully grown from aqueous solution by solvent evaporation technique. As-grown crystals were analyzed by different instrumentation techniques such as X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) spectra and UV-vis near infrared (NIR) transmittance spectra. Thermal behavior has been studied with TGA/DTA analyses. The optical second harmonic generation (SHG) conversion efficiency of LAMD was determined using Kurtz powder technique and found to be 1.5 times that of KDP.
Synthesis, structure and properties of a new nonlinear optical material: zinc cadmium tetrathiocyanate
In this communication, a new nonlinear optical crystal of coordination complex, zinc cadmium tetrathiocyanate (ZnCd(SCN)4), is reported. It was successfully synthesized through several reactions in water. For the crystal structure, optical and thermal characterization were determined by elemental analysis, X-ray diffraction, infrared spectroscopy, differential scanning calorimeter, thermogravimetric analysis, and transmission spectrum. It belongs to the tetragonal system, space group I4, with a = 11.135(2), c = 4.3760(10) A, and z = 2. It exhibits powder SHG efficiencies superior to that of cadmium mercury thiocyanate (CMTC) and over 10 times that of urea, and the UV transparency cutoff is 290 nm, which is shifted to violet band 90 nm, compared with that of CMTC.
DIFFERENTIAL CALCULUS OF SEVERAL VARIABLES WITH MATHEMATICA OR MAPLE
The use of Computer Algebra Systems (CAS) in Mathematical Laboratories at Engineering Schools is increasing. Therefore, it has become necessary to undertake a new educational approach in the teaching of many mathematical topics. Obviously it is not possible to give the same lectures as in the 1950,s. The CAS allows us to experiment and teach in “a different way”. The students' mathematical knowledge at the beginning of their studies in the University is completely different. Moreover we have fewer credits assigned to Mathematical topics in engineering curriculum. The objective of he authors, professors of different Spanish Universities, is to try to demonstrate a new way to use the CAS, concretely Maple and Mathematica, as a support in the teaching of Differential Calculus of Several Variables. They take advantage of the computer's graphical capacities to sketch the graphs of surfaces defined in explicit, parametric or implicit form. They survey the general topics: limits, partial derivatives, differentiability, chain rule, implicit functions and extreme values. For each topic, they give a few basic instructions of the CAS used; afterwards they give several examples, in increasing order of difficulty, and finally the students must solve exercises and try to establish a general procedure for a quite general problem. In this paper we have included several examples used in this survey.