Effect of phosphatidylserine content on the partition coefficients of diazepam and flurazepam between phosphatidylcholine-phosphatidylserine bilayer of small unilamellar vesicles and water studied by second derivative spectrophotometry

The affinity of the psychotropic benzodiazepine drugs diazepam (DZ) and flurazepam (FZ) to phosphatidylserine (PS) was examined since PS is abundantly contained in brain membranes. The effect of PS content on the partition coefficients (K(p)s) of these drugs between phosphatidylcholine (PC)-PS bilayer membranes of small unilamellar vesicles (SUV) and water was measured using second derivative spectrophotometry. The second derivative spectra of DZ and FZ measured in the solutions containing various amounts of PC-PS SUV clearly showed derivative isosbestic points and a distinct derivative intensity change depending on the amount of the SUV added. The derivative intensity differences (AD) of the drugs before and after addition of the SUV suspension were measured at a specific wavelength. Using the AD values, the Kp values were calculated and obtained with relative standard deviation of below 10%. The Kp values of both drugs increased according to the PS content in the PS-PC bilayer membranes of the SUV proving that both have higher affinity to the PC-PS bilayer membranes than to PC membranes. The effect was much larger for FZ, i.e., the Kp value of FZ at 30 mol% PS content increased to about five times the value for the PC SUV. This can be explained by the fact that at the experimental pH of 7.4, 80% of FZ molecules are in a cationic form (pKa=8.1), so that these molecules are highly accessible to the negatively charged PS molecules. The results support the rapid and high distribution of DZ and FZ in the central nervous system after their administration.     

Cyclodextrin-enclosed substances of Brazilian propolis

By using beta-cyclodextrin-inclusion as a unique technique, an efficient separation of pharmacologically active phenolic compounds from Brazilian propolis was achieved to provide one new compound, 3-(3-hydroxy-3-methyl-butyl)-5-prenyl-4-hydroxycinnamic acid, together with two common cinnamic acid derivatives, artepillin C and capillartemisin A, and two known flavanols, aromadendrin and 3,5,7-trihydroxy-4'-methoxyflavanol.     

A molecular orbital treatment of the electronic spectra of some tryptamines

The electronic absorption spectra of tryptamine, 5-methoxytryptamine, 6-fluorotryptamine, N-acetyl-5-hydroxytryptamine, gramine, and melatonin were investigated. The observed transitions were π–π*, and the values of band maxima and intensity reflected an extent of interaction between the indole ring and the alkylamine side chain. Molecular orbital calculations at the level of INDO /S –CI were performed on all the studied molecules. State functions and transition energies were calculated. The correspondence between the experimental and theoretical results was satisfactory. © 1992 John Wiley & Sons, Inc.     

Single exposure photography applied to a slow flow field

A speckle photography technique has been applied to measuring the velocity profiles of laminar and turbulent flow through pipes of circular cross-section. A single exposure photography technique has been used to visualize slow fluid flow. The fluids used were seeded with tracer particles whose size range from 20 to about 120 μm in diameter. A mathematical expression representing the recorded intensity is presented. A single exposure with a long exposure time was taken on a holographic film material. The recorded intensity was represented by the convolution product of the image formed and a rectangular function representing a one-dimensional continuous motion. The analysis shows that the intensity distribution of the Fourier spectrum of the diffracted image follows a sinc² function on a noise background representing the scattered light of the tracer particles.     

Relationship between the cohesive strength and the tack of elastomers

The autohesion (tack) and cohesion of a random styrene-butadiene elastomer have been examined as a function of test temperature and speed using a T-peel geometry. Both properties have been reduced to a single master curve by horizontally shifting the data with the same set of shift factors. The cohesive strength increases with increasing reduced test rate Ra_T and appears to approach a plateau at the highest rates. Tack also increases with Ra_T but decreases abruptly at a critical rate and peeling the occurs in a stick-slip fashion. Tack again increases at sufficiently high test rates. In the range of rates where tack is maximized, its value is essentially the same as its cohesive strength. Above or below this range, tack is substantially less than the elastomer's cohesive strength. Mechanisms are proposed to explain why relative tack (i.e., tack divided by cohesive strength) is not a simple measure of the extent of completion of a tack bond and may indeed be equal to one in spite of incomplete tack bond formation.     

The extended law of corresponding states and the intermolecular potentials for He?He and Ne?Ne

A direct inversion procedure is used to obtain the pair interaction potentials for He and Ne from the extended law of corresponding states over the temperature range from absolute zero to the onset of ionization. We have used the experimentally reduced viscosity collision integrals obtained from the corresponding states correlation and performed an INVERT to determine the reduced potential energy curve corresponding to the collision integral. This directly determined potential is in excellent agreement with the potential independently obtained from molecular beam scattering measurements. © 1995 by John Wiley & Sons, Inc.     

Solving a multi-objective multi-skilled manpower scheduling model by a fuzzy goal programming approach

Manpower scheduling is an intricate problem in production and service environments with the purpose of generating fair schedules that consider employers’ objectives and employees’ preferences as much as possible. However, sometimes, vagueness of information related to employers’ objectives and employees’ preferences leads to the fuzzy nature of the problem. This paper presents a multi-objective manpower scheduling model regarding the lack of clarity on the target values of employers’ objectives and employees’ preferences. Hence, a fuzzy goal programming model is developed for the presented model. Afterwards, two fuzzy solution approaches are used to convert the fuzzy goal programming model to two single-objective models. Finally, the results obtained by both single-objective models are compared with each other to select the solution that has the greatest degree of the satisfaction level of employers’ objectives and employees’ preferences.     

Identification problems for degenerate parabolic equations

This paper deals with multivalued identification problems for parabolic equations. The problem consists of recovering a source term from the knowledge of an additional observation of the solution by exploiting some accessible measurements. Semigroup approach and perturbation theory for linear operators are used to treat the solvability in the strong sense of the problem. As an important application we derive the corresponding existence, uniqueness, and continuous dependence results for different degenerate identification problems. Applications to identification problems for the Stokes system, Poisson-heat equation, and Maxwell system are given to illustrate the theory.     

S-Noetherian Rings of the Forms 𝒜[X] and 𝒜[[X]]

Let 𝒜 = (A _n ) _n≥0 be an ascending chain of commutative rings with identity, S ? A ₀ a multiplicative set of A ₀, and let 𝒜[X] (respectively, 𝒜[[X]]) be the ring of polynomials (respectively, power series) with coefficient of degree i in A _i for each i ∈ ?. In this paper, we give necessary and sufficient conditions for the rings 𝒜[X] and 𝒜[[X]] to be S ? Noetherian.