Electro-optical properties of 4,4-bis-[omega-(4-cyanobiphenyl-4yloxy)alkyloxy]biphenyls nematics

Electro-optical properties of nematics of the trimer series 4,4-bis-[omega-(4-cyanobiphenyl-4yloxy)alkyloxy]biphenyls have been investigated by the method of orientational elastic deformations in electric fields. The number n of CH2 groups in the oxyalkyl fragment was varied from n 2 to n 10. A strong odd-even effect was observed in the optical anisotropy Deltan and in the values of the threshold potential V0 for the trimer nematics. These effects are, respectively, caused by oscillations of the degree of inter- and intra-molecular orientational order when n is varied. The great difference in the dependences of Deltan and V0 on n is discussed and compared with data for dimers.     

On inversion of linear descriptor-variable control systems containing input derivatives

Linear control systems of the form E = Ax + Bv, y = Cx + Dv,are considered, where v is a column composed of the controlu and its first k derivatives, and E is a singular square matrix.This problem is this: find a system R = Fz + Gw, Lv = Hz + Jw,where w is some linear combination of y (the output of the originalsystem) and its derivatives. For the solution of this problem,a method (based on the use of matrix generalized inverse) isdeveloped that can be applied both to time-invariant and totime-varying systems. For the time-invariant case, a numericalprocedure is presented that either yields a system of the desiredform in which the coefficient matrices are of the smallest possibledimensions or shows that there is no such system.     

PHOTOCONTROL OF HYPOCOTYL ELONGATION IN LIGHT-GROWN Cucumis sativus L. PHOTOSYNTHETIC REQUIREMENT FOR A FLUENCE RATE DEPENDENT PHYTOCHROME RESPONSE

We investigated the role of photosynthesis in the photocontrol of extension growth of the hypocotyl of light-grown Cucumis sativus L. Previous work [Gaba and Black (1985b) Plant Physiol. 79 , 1011] demonstrated that the inhibition of cucumber hypocotyl elongation is a fluence rate dependent response in red light. However, the relative contributions of phytochrome and photosynthesis to the photon flux dependent inhibition response were not clear. Here we have shown that photoperception by the foliar cotyledons as well as the hypocotyl itself are responsible for fluence rate dependence in red light. The inhibitor of photosynthesis diuron [3-(3,4-dichlorophenyl)-1, 1-dimethylurea] reduced both the magnitude of inhibition and the fluence rate dependency in red light, indicating an involvement of photosynthesis. Furthermore, the growth of non-pigmented seedlings (treated with the herbicide norflurazon) was less inhibited by red light, with no fluence rate dependency. In particular, inhibition due to cotyledon photoperception was completely lost in non-pigmented (norflurazon-treated) plants, and much reduced by diuron treatment. Hypocotyl-perceived red light inhibition was only slightly reduced by treatment with norflurazon and diuron. Photosynthesis was compared directly to photo-inhibition of growth: the photon flux response curve of oxygen evolution of green Cucumis cotyledons was distinctly different from that of hypocotyl inhibition. In conclusion, photosynthesis is an essential requirement for the cotyledon-perceived inhibition, but the response itself is not due to photosynthesis.     

CHEMICAL SENSITIZATION OF TABULAR－GRAIN EMUL－SIONS IN THE PRESENCE OF SENSITIZING DYE

Investigations sensitometry,were made via the study of crystal morphologies,turbidity measurement spectrometry,and dye leaching test.     

INTENSITY STUDY OF LIF SPECTRUM FOR THE B0u→X0g SYSTEM OF A TELLURIUM NATURAL SAMPLE

The fluorescence spectrum of a tellurium sample in its natural isotopic abundance, induced by the 4764.8 Å line of an argon ion laser is studied. The study of natural tellurium samples allows us to bring out and analyze the intensity of three fluorescence series not previously reported. Photographic plates and densitometric techniques were used when recording experimental intensities. The radiative transition probabilities for the observed fluorescence series were calculated by using hybrid Perturbed-Morse-Oscillator (PMO)-Rydberg–Klein–Rees (RKR)- Long Range potential energy curves for the B0⁺_u and X0⁺_g states and a function for the transition dipole moment in the framework of the r-centroid approximation. Radiative lifetimes of the rovibrational levels for the upper state pumped by the laser line have also been calculated. The transition probabilities and lifetimes are in good agreement with the corresponding observed measurements usually within the experimental uncertainty.     

A simple convex optimization problem with many applications

This paper presents an algorithm for the solution of a simpleconvex optimization problem. This problem is a generalizationof several other optimization problems which have applicationsto resource allocation, optimal capacity expansion, and vehiclescheduling. The algorithm is based on a constraint-relaxationapproach. It is easily implemented and transparent, and canbe used to solve even fairly large problems by hand calculator.     

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)     

UNUSUALLY HIGH AFFINITY OF Zn(II)-TETRADIBENZOBARRELENOOCTABUTOXY- PHTHALOCYANINE FOR LOW-DENSITY LIPOPROTEINS IN A TUMOR-BEARING MOUSE

Abstract— An important factor in determining the efficacy of photosensitizing compounds in photodynamic therapy of tumors is the level to which tumors take up the photosensitizers after systemic injection. This parameter seems to be related to the transport modalities of the photosensitizer in the bloodstream. In this work the photosensitizer Zn(II)-tetradibenzobarreleno-octabutoxyphthalocyanine was shown to have an unprecedentedly high association with low-density lipoproteins (71% of the phthalocyanine in the plasma) when delivered in Cremophor micelles to tumor-bearing mice. This was accompanied by a particularly high tumor uptake at 24 h post-injection.