Determination of sildenafil by various methods and in various media is reviewed in this paper. The methods used consist of ultraviolet (UV) spectroscopy, thin layer chromatography (TLC), and high-performance liquid chromatography (HPLC). These methods were used to determine the amount of sildenafil in pharmaceutical preparations, soft drinks, and biological liquids. HPLC was used for evaluation of pharmacokinetic parameters of sildenafil. It is concluded that HPLC is the most reliable and applicable method in this regard. 

In this paper, by using Mond-Pecaric method we provide some inequalities for connections of positive definite MATRICES. Next, we discuss specifications of the obtained results for some special cases. In doing so, we use a-arithmetic, a-geometric and a-harmonic operator means.

In this paper, by using the notion of fuzzy subsets, the concept of F-permutation is introduced. Then by applying this notion the concepts of presentation of an F-polygroup, graph of an F-permutation and F-permutation MATRICES are investigated.

In this paper we give more results about inner radius spectrum of operators on Hilbert spaces with several examples. Also, we established an inequality for inner radius spectrum of a positive operator matrix and its minimum moduli block matrix.

In this paper, the inverse eigenvalue problem for the bordered diagonal MATRICES are reconsidered whose elements are equal to zero except for the first row, the first column and the diagonal elements. The necessary and sufficient conditions for existence of a symmetric bordered diagonal matrix from special spectral data have been determined. A new algorithm to make such MATRICES is derived and some numerical examples are given to illustrate the efficiency of the method.

In 2009 B. Zheng et al. proposed two modified Gauss-Seidel (MGS) methods for linear system with M-MATRICES. In this paper, we use the preconditioners introduced by B. Zheng et al. For modified Jacobi method. The comparison theorems and numerical examples show that the proposed methods are superior to the classical Jacobi method.

In this paper we consider the special classes of Sonnenschein MATRICES, namely the Karamata MATRICES...

In this paper, a recursive algorithm is presented to generate some exponent MATRICES which correspond to Tanner graphs with girth at least 6. For a J ´ L exponent matrix E, the lower bound Q (E) is obtained explicitly such that (J, L) QC LDPC codes with girth at least 6 exist for any CIRCULANT permutation matrix (CPM) size m ³ Q (E). The results show that the exponent MATRICES constructed with our recursive algorithm have smaller lower-bound than the ones proposed recently with girth 6.

This paper is concerned with the problem of finding a lower bound for certain matrix operators such as Hausdorff and Hilbert MATRICES on sequence spaces lp(w) and Lorentz sequence spaces d(w,p), which is recently considered in [7,8], similar to [13] considered by J. Pecaric, I. Peric and R. Roki. Also, this study is an extension of some works which are studied before in [1,2,7,8].