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Micropropagation of matureTaxus marieiwas achieved using bud explants derived from approximately 1,000-year-old field-grown trees. Bud explants derived from 1-year-old stecklings raised from rooted cuttings of these trees were included in this study for comparison. Steckling-derived explants collected in different seasons showed high survival rates and good growth performance in vitro, whereas the survival of mature tree-derived explants was highly season dependent, with satisfactory survival in early spring only. During successive subculturing, tissue browning was observed in cultures of both origins, but the problem was circumvented by supplementing the basal medium with 1 g l–1activated charcoal and 100 mg l–1silver nitrate. The steckling-derived cultures performed better than mature tree-derived cultures in terms of shoot multiplication and rooting ability. New shoots of both origins exhibited plagiotropic growth, but steckling-derived shoots had a smaller plagiotropic angle (near vertical) than mature tree-derived shoots. In both cases, the plagiotropic angles decreased after these subcultures were maintained in shoot multiplication conditions for half a year. Orthotropic growth was restored in 25% and 10% of the steckling- and mature tree-derived cultures, respectively.

A standard PID controller has three adjustable parameters, i.e., the proportional gain, and the integral and derivative time constants. Usually, conventional frequency domain techniques of single-loop feedback control design use only gain and phase margin specifications to determine these parameters. As a result, there remains one degree of freedom in selecting controller parameter to meet the specification of gain and phase margins. Motivated by the availability of analytical and/or efficient numerical methods of computing integral of square error (ISE) for systems with/without a time delay, we suggest in this paper to adjust the remaining degree of freedom in PID parameters to minimize a quadratic cost functional. Instead of solving a constrained nonlinear optimization problem, we formulate the design problem in a form such that it can be easily solved by a path-following algorithm while giving the global optimum.

The problem of evaluating a cross-covariance functional of the form 12πi∫-i∞i∞F(s)G(-s)dsarises, e.g., in parametric optimization oflinear systems and in optimal linear filtering. In this paper, an algorithm is presented for computing cross-covariance functionals for linear systems with multiple commensurate time delays. The algorithm is based on converting a crosscovariance functional into an equivalent auto-covariance one. Then by utilizing an existing partialfraction-expansion scheme for a class of two-dimensional rational transfer functions, the evaluation ofa cross-covariance functional is reduced to the determination ofsymbolic inversion ofa polynomial matrix and the spectral factorization of a finite-degree real-coefficient polynomial. It is shown that the presented algorithm can be extended to systems having non-commensurate time delays through either introducing fictitious delays or adjusting time delays with rational approximation such that the resulted delays are commensurate. In order to illustrate the effectiveness of the algorithm, an example is provided.

The National Institutes of Health sponsored a randomized, double-blind, multicenter, placebo-controlled trial of flunarizine (FNR) in epileptic patients receiving concomitant phenytoin (PHT) or carbamazepine (CBZ). Because of FNR's long half-life (up to 7 weeks), a parallel rather than crossover design was used. Each patient received an individualized loading dose and maintenance dosage targeted at a 60-ng/ml plasma FNR concentration. Of 93 patients randomized, 92 provided seizure data for the full 25-week treatment period; one placebo-treated patient dropped out for personal reasons. Fifty-four patients received CBZ only, nine received PHT only, and 30 received both CBZ and PHT. Eighty-seven patients had a history of complex partial seizures, and 60 had secondarily generalized seizures. Eight patients discontinued FNR prematurely, all because of adverse neurologic or psychiatric signs or symptoms; depression was the specific cause in three cases. Calculated maintenance dosages, based on single-dose pharmacokinetic profiles, ranged from 7 to 138 mg/day (mean, 40 mg/day). Plasma FNR concentrations generally exceeded the target, with the highest concentrations observed immediately after loading; excluding the first three treatment weeks and all concentrations after a FNR dosage change, the median plasma FNR concentration was 71.7 ng/ml. The percent reduction from baseline seizure rate was statistically greater (p0.002) in the FNR-treated group (mean, 24.4) than in the placebo-treated group (mean, 5.7).

Felbamate (2-phenyl-1,3-propanediol dicarbamate) has a favorable preclinical profile in animal models of epilepsy. We present the results of a double-blind, randomized, placebo-controlled clinical trial in patients with partial seizures. Criteria for entry included a requirement for four or more partial seizures per month despite concomitant therapeutic blood levels of phenytoin and carbamazepine. Fifty-six patients (mean age, 31.4 years; 32 men, 24 women) completed the trial. The mean seizure frequencies for the 8-week periods analyzed were felbamate 34.9, placebo 40.2. Felbamate was statistically superior to placebo in seizure reduction, percent seizure reduction, and truncated percent seizure reduction. The mean felbamate dosage was 2,300 mg/d. Plasma felbamate concentrations ranged from 18.4 to 51.9 mg/l, mean 32.5 mg/l. Adverse experiences during felbamate therapy were minor and consisted primarily of nausea and CNS effects. This trial indicates that felbamate is safe and effective in the treatment of comedicated patients with severely refractory epilepsy.

The desorption of C12E8 out of an overcrowded interface due to the sudden shrinkage of a pendant bubble in a quiescent surfactant solution is studied. A video-enhanced pendant bubble tensiometry is utilized for the measurement of the relaxation in surface tension due to the desorption of surfactant. The desorption process is found to be diffusive−kinetic mixed controlled. Rate constants of adsorption/desorption are computed by comparing these tension profiles with numerical solutions, which consider both bulk diffusion and kinetic desorption processes. The values of the kinetic rate constants of C12E8 obtained from the desorption experiment are nearly the same as that obtained from the clean adsorption study (Lin, S. Y., et al., Langmuir 1996, 12, 6530). The concept that there exists a shift in controlling mechanism from diffusion control at dilute concentration to mixed diffusion−kinetic control at more elevated bulk concentration for C12E8 is therefore confirmed.

The recent serial section electron microscopic studies by Adamson and Michel (1993) on microves gels of frog mesentery have revealed that the large pores in the junction strand of the interendothelial cleft are widely separated 150 nm wide orifice-like breaks whose gap height 20 nm is the same as the wide part of the cleft. In this paper a modified version of the model in Weinbaum et al. (1992) is first developed in which this orifice structure is explored in combination with a random or ordered fiber matrix layer that is at the luminal surface and/or occupies a fraction of the wide part of the cleft. This basic orifice model predicts that for the measured Lp to be achieved the fiber layer must be confined to a relatively narrow region at the entrance to the cleft where it serves as the primary molecular filter. The model provides a much better fit of the permeability P for intermediate size solutes between 1 and 2 nm radius than the previous model in Weinbaum et al., where the junction strand breaks were treated as finite depth circular or rectangular pores, but like the previous model significantly underestimates P for small ions. However, it is shown that if a small frequent pore of 1.5 nm radius with characteristic spacing comparable to the diameter of the junction proteins or a continuous narrow slit of approximately 1.5 to 2.3 nm gap height is also present in the continuous part of the junction strand, small ion permeability can also be satisfied. The 1.5 nm radius pore does not significantly change Lp, whereas the continuous narrow slit provides a contribution to Lp that is comparable to, or in the case of the 2.3 nm slit greater than, the widely spaced 150 nm orifices. Thus, for the narrow slit the contribution to Lp from the orifices can be as low as 1.0×10−7 cm/s/cm H2O and it is also possible to satisfy the 2.5 fold increase in permeability that occurs when the matrix is enzymatically removed from the luminal side of the cleft, Adamson (1990). The likelihood of each of these cleft structures is discussed.

Several families of UV-cured polyurethane acrylates were synthesized and the effects of polyol type and molecular weight on their physical properties were investigated. Increasing polyol molecular weight led to a lower polyol glass transition temperature, a smaller amount of a separate urethane acrylate phase, and a larger chain length between crosslinks. The first two effects were reflected in lower modulus and strength at room temperature while the larger chain length between crosslinks led to higher elongation at break (room temperature) and lower modulus at high temperatures. The use of different polyols (polycarbonate, polytetramethylene oxide, polypropylene oxide, and polycaprolactone) primarily affected the room temperature modulus due to differences in the position and breadth of the polyol glass transition. The properties of materials based on isocyanatoethyl methacrylate (IEM) and toluene diisocyanate-2-hydroxyethyl melhacrylate (TDI-HEMA) were also compared.

The thermodynamically more stable diastereomeric rotational isomer I, of 3-(o-tolyl)-5-methyl-2-thioxo-4-oxazolidinone, which is first crystallized out in solution, shows that the ortho methyl substituent is cisoid to the methyl group of the hetero ring, and the thermodynamically less stable isomer II, crystallized later, has both methyl groups in transoid conformation, as is found in X-ray studies. The carbonyl and thiocarbonyl bonds are found to be longer in isomer II than in isomer I, which is attributed to the favored conjugation interaction of carbonyl, thiocarbonyl groups with the lone pair electrons of nitrogen, that may cause the lessened stability of isomer II.

The adsorption of C12E8 onto a clean air−water interface is studied by using a video-enhanced pendant bubble tensiometry. The controlling mechanism for mass transfer changes as a function of bulk concentration; it shifts from diffusion control at dilute concentration to mixed diffusion−kinetic control at more elevated bulk concentration. The adsorption of C12E8 is found to be anticooperative from the equilibrium surface tension data compared with the prediction of the (generalized) Frumkin model. Relaxation profiles of surface tension for C12E8 molecules absorbing onto a freshly created air−water interface for 21 different bulk concentrations are obtained. Comparison is made for the entire relaxation period of the tension data and the model predictions. Values of the diffusion coefficient and the adsorption/desorption rate constants of C12E8 are calculated from these dynamic surface tension profiles.