Stability of Ibuprofen in its Inclusion Complex with β-Cyclodextrin

The ibuprofen--cyclodextrin inclusion complex was prepared by theco-precipitation method. The identity of the obtained product was verified by X-ray and thermogravimetric techniques. The effect of -cyclodextrin on the stability of ibuprofen was analysed.     

The method of lines for parabolic differential-functional equations

Parabolic differential–functional equations with initial-boundaryconditions of Dirichlet type are studied. Spatial derivativesoccurring in the original problem are replaced by suitable differencesand the problem is transformed into an initial-boundary valueproblem for a system of ordinary differential–functionalequations. The Pen-on-type estimation for the right-hand sideof the original equation with respect to the functional argumentis assumed. The convergence of the numerical method of linesis proved. The differential inequalities technique is applied.     

Hidden symmetries of energy-conserving differential equations

Hidden symmetries of second-order differential equations whichare invariant under a one-parameter Lie point group and areof the energy-conserving form are analysed as an inverse problemfor some particular cases. These hidden symmetries occur asadditional one-parameter lie point group symmetries in the reducedfirst-order differential equations.     

Solid Phase Microextraction (SPME)

Solid phase microextraction (SPME) was developed to address the need for a fast, solvent-free and field compatible sample preparation method. It has been applied to a range of applications including environmental, industrial hygiene, process monitoring, clinical, forensic, food and drug analysis. In SPME, coated fibers are used to isolate and concentrate analytes into a range of coating materials. After extraction, the fibers are transferred, with the help of the syringe-like handling device, to analytical instruments for separation and quantification of the target analytes.In the past 20 years the number of instrumental techniques available to the chemist has grown exponentially. In order to help our readers keep up with this rapidly growing field, tutorial articles on chemical instrumentation will be a regular feature of The Chemical Educator. The articles are designed to serve as a brief introduction to emerging instrumetal techniques with an outline of the underlying principles and major applications. —Martin Schimpf, Series Editor     

The Urbanik generalized convolutions in the non-commutative probability and a forgotten method of constructing generalized convolution

The paper deals with the notions of weak stability and weak generalized convolution with respect to a generalized convolution, introduced by Kucharczak and Urbanik. We study properties of such objects and give examples of weakly stable measures with respect to the Kendall convolution. Moreover, we show that in the context of non-commutative probability, two operations: the q-convolution and the (q,1)-convolution satisfy the Urbanik??s conditions for a generalized convolution, interpreted on the set of moment sequences. The weak stability reveals the relation between two operations.     

Hidden symmetries and nonlocal group generators for ordinary differential equations

Hidden symmetries of ordinary differential equations (ODEs)are studied with nonlocal group generators. General forms aregiven for an exponential nonlocal group generator of an ODEthat is reduced from a higher-order ODE, which is expressedin canonical variables and which is invariant under a two-parameterLie group. The nonlocal group generator identifies a type Ihidden symmetry. Type II hidden symmetries are found in somereduction pathways of an ODE invariant under a solvable, nonabelian,three-parameter Lie group. The algorithm for the appearanceof the type II hidden symmetry is stated. General forms forthe reduced nonlocal group generator, which identifies the typeII hidden symmetry, are presented when the other two commutingoriginal group generators are in normal form.     

OXYGEN LIMITATION OF DIRECT TUMOR CELL KILL DURING PHOTODYNAMIC TREATMENT OF A MURINE TUMOR MODEL

The relationship between levels of in vivo accumulated photosensitizer (Photofrin II), photodynamic cell inactivation upon in vitro or in vivo illumination, and changing tumor oxygenation was studied in the radiation-induced fibrosarcoma (RIF) mouse tumor model. In vivo porphyrin uptake by tumor cells was assessed by using 14C-labeled photosensitizer, and found to be linear with injected photosensitizer dose over a range of 10 to 100 mg/kg. Cellular photosensitivity upon exposure in vitro to 630 nm light also varied linearly with in vivo accumulated photosensitizer levels in the range of 25 to 100 mg/kg injected Photofrin II, but was reduced at 10 mg/kg. Insignificant increases in direct photodynamic cell inactivation were observed following in vivo light exposure (135 J/cm2, 630 nm) with increasing cellular porphyrin levels. These data were inconsistent with expected results based on in vitro studies. Assessment of vascular occlusion and hypoxic cell fractions following photodynamic tumor treatment showed the development of significant tumor hypoxia, particularly at 50 and 100 mg/kg of Photofrin II, following very brief light exposures (1 min, 4.5 J/cm2). The mean hyupoxic cell fractions of 25 to 30% in these tumors corresponded closely with the surviving cell fractions found after tumor treatment in vivo, indicating that these hypoxic cells had been protected from PDT damage. Inoculation of tumor cells, isolated from tumors after porphyrin exposure, into porphyrin-free hosts, followed by in vivo external light treatment, resulted in tumor control in the absence of vascular tumor bed effects at high photosensitizer doses only.(ABSTRACT TRUNCATED AT 250 WORDS)