Electron microscopy of tRNA crystals. I. Thin crystals negatively stained with uranyl acetate

The first attempt to study crystal structures of tRNA by electron microscopy is described. Sufficiently thin crystals were prepared from yeast tRNAphe. The thickness of the thinnest was estimated at 130 A corresponding to a bilayer of the molecules. The L-shaped structure seemed to be maintained even after the negative staining with uranyl acetate. Optically filtered images from electron micrographs were compared with those simulated from the drawing of the molecular model by optical transform. The results suggest that the observed images reflect the real molecular arrangements within the crystal lattice although the shape of tRNA molecules seems to be somewhat modified by the uneven staining.     

Protein binding effects of salivary excretion of phenobarbital in dogs

The salivary excretion of phenobarbital was investigated by collecting parotid saliva (Pr) and mandibular-sublingual saliva (MS) separately after intravenous administration in beagle dogs. (1) The alterations in the proportions of saliva secreted by the different glands were produced by salivation stimulants such as citric acid, ascorbic acid, sodium chloride and sodium glutamate. (2) The phenobarbital concentrations in both Pr amd MS were lower than those in plasma. The drug concentrations in MS were significantly lower than in Pr with stimulus of 10% citric acid of 15% sodium chloride (p less than 0.05). There was a significant correlation between phenobarbital concentration in each saliva and plasma specimen ( p less than 0.05). (3) The stimulation with 10% citric acid produced higher saliva /plasma drug concentration ratios (S/P ratios: 0.923 +/- 0.175 for Pr, 0.633 +/- 0.073 for MS) than that with 15% sodium chloride (S/P ratios: 0.597 +/- 0.071 for Pr, 0.509 +/- 0.067 or MS). (4) The S/P ratios were hardly influenced by salivary flow rates, at least under the experimental conditions examined in this study. (5) The increased S/P ratios were observed with higher salivary pH and then the equation of Matin et al. 3) seemed to hold for the average values of salivary pH and S/P ratio. (6) The stimulation with 10% citric acid produced higher protein concentration in saliva and higher S/P ratio than that with 15% sodium chloride following alternate stimulations in the same dog.     

Mode behaviour in a tapered multimode fibre

A derivation based on ray tracing and the local plane-wave approximation is used to show the behaviour of waveguide modes in a linearly tapered multimode fibre having a step-index profile. The azimuthal mode order l is invariant through the taper, and, for suitably designed tapers, the changes in the radial mode order m and the lateral component u are negligible. A formula for designing such tapers is presented.     

Measurement of nonlinear distortion in photodiodes

The 2nd-order nonlinear distortion of avalanche photodiodes (TIXL-55, C-20817) was found to be less than ?60 dB for an incident average optical power of ?20 dBm modulated at a peak depth of 75%. p-i-n photodiodes (HP 5082-4207) were found to have 2nd-order-distortion levels below the noise level. A method using three independent optical signal sources was employed in the measurement.     

Electrical responses of chalcogenide films in the photodoping process

The photodoping process in Al/AsS₂/Ag tri-layer films has been studied through measurements of electrical impedance, photodoped-layer thickness, and photocurrent. Frequency dependence of the impedance suggests that the sample under photodoping can be approximated by an equivalent electrical circuit. A thickness of photodoped layers, which is estimated from the impedance, is in agreement with a geometrical thickness measured by an atomic force microscope for chemically etched samples. Under the photodoping (with zero bias voltages), a photocurrent remains constant at ~ 5 pA, and near the completion it increases to ~ 1 nA, which is followed with a gradual decrease. By applying a bias voltage between the top (semi-transparent Al) and bottom (Ag) electrodes, we can change a photodoping rate by an order. This rate change is attributable to the modulation of an effective electric field in the doped layer, which induces the motion of Ag ions.     

Recognition and effective degradation of 17beta-estradiol by anti-estradiol-antibody-immobilized TiO(2) nanoparticles

Polyelectrolyte polyacrylic acid (PAA), used in the chemical modification of titanium dioxide (TiO(2)) nanoparticles, allows TiO(2) nanoparticles to remain in suspension at neutral pH. The anti-17beta-estradiol (E2) antibody was immobilized on PAA-modified TiO(2) (PAA-TiO(2)) nanoparticles via covalent bonding between the carboxylic acid of PAA and the amino group of the antibody. The anti-E2-antibody-immobilized TiO(2) (E2Ab-PAA-TiO(2)) nanoparticles can form a suspension at neutral pH, with a particle size of less than 100 nm. The E2-PAA-TiO(2) nanoparticles caused the photocatalytic degradation of a typical TiO(2) substrate, methylene blue. The anti-E2 antibody immobilized on the TiO(2) surface recognized and bound E2 in the solution, thereby improving the efficiency of E2 degradation compared with that of PAA-TiO(2) nanoparticles. These results demonstrate that the E2Ab-PAA-TiO(2) nanoparticles developed in this study can be used in water treatment technology. Furthermore, this strategy of immobilizing proteins on nanoscale TiO(2) particles creates new applications not only in the treatment of environmental waste, but also in medical and public sanitation processes.     

Clinical evaluation of nitrite test for the detection of bacteriuria

A nitrite test for bacteriuria was compared with routine microscopic examination in 1,318 clinical urine specimens and with bacterial culture in 132. Sensitivity, specificity, positive predictive value and accuracy rate are as follows; for diagnosis of bacteriuria more than 10(4) CFU/ml, 53.4%, 88.6%, 90.4 and 65.2%, respectively; for more than 10(5) CFU/ml, 55.4%, 87.8%, 88.4% and 67.2%, respectively. The positive rate for the nitrite test was 21.4% for bacteriuria of > or = 10(4) CFU/ml in gram positive cocci and 56.9% in gram negative rods. False negative results were obtained from gram positive cocci without nitrate reductive activity or from patients with acute uncomplicated cystitis because of insufficient incubation time in urinary tract. However, this simple test is valuable in the detection of bacteriuria in clinical practice with high specificity.     

Generation of 10 GHz similariton pulse trains from 1.2 km-long erbium-doped fibre amplifier for application to multi-wavelength pulse sources

A 10 GHz similariton pulse train is generated from a 1.2 km-long erbium-doped fibre amplifier and applied to a multi-wavelength pulse source. Slicing the spectrum of the similariton pulse train, a 10 Gbit/s transmitter was constructed, which has excellent Q-factors of over 25.3 dB in the entire bandwidth. Such uniform characteristics of the sliced pulse train originate from the high spectral flatness of the similariton.     

A mixed dispatching rule approach in FMS scheduling

Short-term scheduling in flexible manufacturing systems (FMSs) is a difficult problem because of the complexities and dynamic behavior of FMSs. To solve this problem, a dispatching rule approach is widely used. In this approach, however, a single dispatching rule is usually assigned for all machines in a system during a given scheduling interval. In this paper, a mixed dispatching rule which can assign a different dispatching rule for each machine is proposed. A search algorithm which selects an appropriate mixed dispatching rule using predictions based on discrete event simulation is developed for this approach. The search algorithm for the mixed dispatching rule is described in detail. The effectiveness (in meeting performance criteria) of the mixed dispatching rule and the efficiency of the search algorithm relative to exhaustive search (complete enumeration) is demonstrated on an FMS model. The mixed dispatching rule approach performs up to 15.9% better than the conventional approach, and is 4% better on average. The statistical significance of the results is dicussed.