Anion exchange membranes prepared from chloromethylstyrene and 2-methyl-5-vinylpyridine

Strongly basic anion exchange membranes were prepared by the radical copolymerization of chloromethylstyrene and 2-methyl-5-vinylpyridine. The formation of a three-dimensional structure and the presence of the quarternary pyridinium group were confirmed by infrared spectrum analysis and its strongly basic anion exchange properties. Their electrochemical properties and morphology were compared with those of the anion exchange membranes prepared from chloromethylstyrene-divinylbenzene and 2-methyl-5-vinylpyridine-divinylbenzene. The chloromethylstyrene-2-methyl-5-vinylpyridine membranes were proved to have larger anion exchange capacity, smaller electric resistance, larger water content, and higher permeability than the chloromethylstyrene-divinylbenzene and 2-methyl-5-vinylpyridine-divinylbenzene membranes. Also, the membranes have heterogeneity in the cross-linking structure.     

Morphology and albumin secretion of adult rat hepatocytes cultured on a hydrophobic porous expanded polytetrafluoroethylene membrane

Repeated addition of insulin, together with an initial addition of the reduced form of glutathione (GSH) and a chelator, aurintricarboxylic acid (ATA), was proposed as a strategy for the dynamic control of apoptosis in serum-free culture of Chinese hamster ovary (CHO) cells. Insulin suppressed cell death in serum-free culture by means of lowering intracellular reactive oxygen species levels via an increase in the specific glucose consumption rate. This effect of insulin addition was found not only at 0 h but also at 48 h during serum-free cultivation. In consideration of the reduction of insulin by GSH, insulin was again added at 24 h following the initial addition during the serum-free cultivation. The repeated addition of insulin decreased cell death and increased the production of tissue plasminogen activator compared with the single addition at 0 h.     

Microscopic computer tomography measurement of nonaxisymmetricallydistributed optical fiber refractive index

A nonaxisymmetrically distributed method for measuring the refractive index of an optical fiber is described. The light intensity distribution is observed with a microscope when an optical fiber is latterally illuminated by collimated light. The integrated refractive-index difference along the projective line is obtained by performing two integrations of the light intensity. The fiber is rotated, and the observation and calculations are repeated at each angle of rotation. The refractive-index pattern over the fiber cross section is reconstructed by computer tomography     

Design of stabilized digital inverse systems

As is well known, due to the existence of unstable limiting zeros and/or the minimum phase property of continuous-time systems, there are many cases that the discretized systems are of non-minimum phase. In this case, it is impossible to construct a stable digital inverse by usual methods. However, in this paper, we will show that if the inter-sample output is used in the design, one can always construct a stable digital inverse system.     

All-optical bit-pattern matching with photonic switching arrays

An all-optical XOR logic circuit is demonstrated using photonic switching arrays that integrate multiple-quantum-well reflection modulators and phototransistors. The switching element performs a Boolean logic A B operation on two binary input light signals that are separately incident on the phototransistor and modulator. The XOR logic function is derived by optical coupling of the switching elements. The device features high contrast that enables high-speed bit pattern matching in parallel     

Generation of 0.64-THz-width optical sidebands by a novel electrooptic modulator for the purpose of forming ultrashort optical pulses

A novel type of electrooptic phase modulator suitable for deep modulation at higher frequencies has been designed and constructed. This modulator can produce an extremely broad optical sideband, which is useful for forming ultrashort optical pulses. In experiments, phase modulation with a modulation index of 34 rad has been successfully obtained at 9.35 GHz, and thereby optical sidebands extending over as wide as 640 GHz have been attained. The sidebands produced are broad enough to form single-picosecond pulses using the chirping-compression method.     

A voltage source PWM rectifier-inverter with feedforward control of instantaneous power

In general, diode rectifiers with electrolytic capacitors on the dc side have been used as dc power supplies for voltage source inverters. This type of rectifiers, however, causes many problems such as poor power factor and harmonics. Recently, voltage source PWM rectifier-inverters have been studied to provide the following advantages; (1) harmonic-free on both ac sides; (2) unity power factor on the input ac side; (3) power flow of either direction or power regeneration; (4) reduction of the dc capacitor. It is, however, difficult for a conventional one to regulate the capacitor voltage on transient states because of having only a voltage feed-back loop. This paper describes a voltage source PWM rectifier-inverter with feed-forward control of instantaneous power. Based on the pq theory, the instantaneous power which is calculated in the control circuit of the inverter is fed forward to the control circuit of the rectifier. The feed-forward control of instantaneous power makes a great contribution to sufficiently suppress voltage fluctuation of the dc capacitor on transient states. Transient characteristics are discussed and some interesting experimental results of a laboratory model are shown.