Frequency-Domain Measurements of Diffusing Photon Propagation in Solid Phantoms

Photon propagation in a highly scattering medium such as living tissue is well described by the photon diffusion equation. In a homogeneous and isotropic case, the equation has analytically been solved for a medium with a simple geometrical shape. We report frequency-domain measurements using slab-shaped solid phantoms. Comparison of the results with computer simulations proves the validity of extrapolated boundary conditions.     

Calculation of Photon Path Distribution Based on Photon Behavior Analysis in a Scattering Medium

We calculated the photon path distribution (PPD) in a scattering medium based on a theoretical analysis, which utilizes the relationship between the photon intensity and photon pathlength. This PPD is defined by local photon pathlengths for photons having total pathlengths of l between the light input points and detection points. The PPD of photons that consist of the impulse response at time t (= l/c) was calculated for a 2-D model. Precise analysis of photon migration in the scattering medium is essential in order to carry out image reconstruction of diffuse optical tomography (DOT). We show the PPD at time t (the total pathlength l = ct) and demonstrate its effectiveness. Our method for describing photon migration is intuitive and allows finding weight functions in DOT.     

ESR,XPS, UV-VIS and FT-IR investigations on the interaction of no and O2 with highly dispersed C60 supported on silica,titania and alkali cation-exchanged Y-zeolites

The characteristics of the radical sources in highly dispersed C₆₀ samples supported on silica, titania ad alkali cation-exchanged Y-zeolite were investigated in the presence and absence of NO and O₂by means of ESR, FT-IR and UV-diffuse reflectance spectroscopies, the results of which were compared with those of the bulk C₆₀ sample. In the presence of O₂, C₆₀ dispersed onto supports was found to easily generate ESR signals in ambient conditions or under UV-irradiation. The intensity of the ESR signal of the C₆₀ samples were found to strongly depend on the dispersibility of C₆₀, the kind of support and the degassing temperature. Based on these results, the nature of these ESR active species in C₆₀ was discussed in detail for the first time. The addition of NO led to a dramatic decrease in the intensity of the ESR signal, its extent also strongly depending on the kind of support, i.e., silica or Y-zeolite and the exchanged-alkali cations on zeolite, i.e., H⁺, Na⁺, Cs⁺, while such a decrease was not observed for the bulk C₆₀.     

Allocation of buffer capacities in queueing networks with arbitrary topologies

Two algorithms are developed to allocateM buffers toN service stations connected arbitrarily in a feed-forward manner. All service times and the interarrival times are assumed to be exponentially distributed. Both methodologies are easy-to-use tools to explore alternative buffer storage configurations and parameter settings during the initial design stages of production systems, communications networks, and flexible manufacturing systems.This research was done while the author was on a sabbatical leave of absence at North Carolina State University, Raleigh, North Carolina.     

Modification of α-santonin VI. Synthesis of (+)-deoxyvernolepin

(+)-Deoxyvernolepin is synthesized from α-santonin via angular methyl activation and subsequent furan ring opening.     

Preparation of macroreticular-type oleophilic anion exchange resin membrane and its permselectivity to halides and thiocyanate

Macroreticular-type oleophilic anion exchange resin membranes containing high-molecular-weight ammonium ions such as tri-n-octylbenzylammonium and tri-n-dodecylbenzylammonium as fixed site were freshly prepared. These membranes were wetted well with water-immiscible organic solvents even in aqueous surroundings. The properties of the membrane, i.e. porosity, water and organic solvent content, capacity and conductivity were determined. The permselectivity of the membrane impregnated with nitrobenzene or o-nitrophenyloctylether to halide and thiocyanate ions was evaluated by measurement of bi-ionic membrane potential and electrodialysis. p]The sequence of the permselectivity was Cl^? < Br^? < I^? < SCN^?, and was consistent with the Hofmeister anion series. The value of the permselectivity was 10–100 times larger than that of usual hydrophilic anion exchange membranes. It was found that the permselectivity of the present membrane was strongly dependent on the separation factor, which was in turn affected by the hydrophobicity of the membrane. The effect of the ion association between fixed ion-exchange site and counter ion on the specific conductance of the membrane was also discussed.     

Formose reaction by polymer-supported thiazolium salts

Thiazolium salt polymers synthesized by quaternization of 4-(4′-vinylphenyl)thiazole (VPT) polymers with methyl iodide had a highly catalytic activity for “the formose reaction.” Their catalytic activities were comparable to that of a low molecular weight analog, 3-methyl-4-phenylthiazolium iodide (MPTI). In the reaction catalyzed by the polymer catalyst, a main product, dihydroxyacetone (DHA), was detected by gas-liquid chromatography. The polymer catalysts were easily recovered from the reaction mixture and reused with a sustained catalytic activity. © 1992 John Wiley & Sons, Inc.     

Block-Copolymerisation. 9. Mitt. Polymerisation des NCA von Methyl-D-glutamat mit telechelem Polystyrol,das Glycolgruppen als aktive Kettnenden enthält

Ohne Zusammenfassung     

Reduction of Rejection Floor of Filter for Ultimate Spectral Efficiency in DWDM Systems

The requirement of the rejection floor level in the wavelength filter was clarified to achieve the ultimate spectral efficiency in DWDM systems. A cascaded filter can satisfy this condition.