Electron microscopic visualization of collagen aggregates without chemical staining.

Lateral, uni-directional aggregates of collagen, segment-long-spacing crystallites (SLS), were made by dialyzing collagen solutions against acetic acid containing ATP, and were examined by transmission electron microscopes without electron staining. There detected were at least 20 dark (electron dense) cross-striations within SLS. The banding pattern was compared with the biochemical and biophysical properties of the amino acid side chains along the collagen molecule. The banding pattern of unstained SLS was mostly correlated with the intramolecular distribution of basic amino acid residues. Since basic amino acids have relatively large side chains, the distribution of mass (molecular weight of amino acids) along the molecule (local density profile) partially explained the cross-striation. Addition of fractions of molecular weight of ATP to basic residues made the local density profile much better correlate to the banding pattern. We conclude that the electron microscopic banding pattern of unstained SLS was generated by the local amount of material or local density profile along the collagen aggregates, which was enhanced by ATP bound to positively charged basic residues. The concept that the electron density correlates with the amount of material is fundamental in electron microscopy, and it has been proven with biological materials in this paper.     

Development of a colon delivery capsule and the pharmacological activity of recombinant human granulocyte colony-stimulating factor (rhG-CSF) in beagle dogs

A peroral dosage form was examined to deliver recombinant human granulocyte colony-stimulating factor (rhG-CSF) to the colon in beagle dogs. A new gelatin capsule with its inside surface coated with ethylcellulose was prepared for this purpose. RhG-CSF was dissolved with propylene glycol and was filled in the capsule. Several kinds of ethylcellulose-gelatin capsules with an ethylcellulose layer of thickness 46 to 221 mm were used. The capsule was filled with propylene glycol solution containing fluorescein as an absorption marker, castor oil derivative and citric acid. The hardness of the capsule was tested after the gelatin layer was dissolved using a hardness tester and was dependent on the thickness of the ethylcellulose layer of the capsule. The time, Tmax, at which plasma fluorescein level reaches its maximum following oral administration of ethylcellulose capsules was used as a parameter for the in-vivo disintegration time of the ethylcellulose capsule into the colon. Capsules of thickness 84 mm with a Tmax of 4-6 h were filled with rhG-CSF solution containing fluorescein and were administered to dogs. After administration, blood samples were collected for 96 h and the blood total leucocyte (BTL) counts were measured as a pharmacological index of rhG-CSF. The maximum BTL count appeared at 10 h then gradually decreased and returned to its normal level at 48 h. These results suggest the usefulness of ethylcellulose capsules for the delivery of rhG-CSF to the colon and the possibility of a new oral rhG-CSF dosage form has been elucidated.     

Biotransformation of isoflavones by Aspergillus niger as biocatalyst

Biotransformation of the isoflavones, 6,7,4′‐trimethoxyisoflavone ( 1 ) and 5,7,4′‐trimethoxyisoflavone ( 2 ) by Aspergillus niger was investigated. Compound 1 was transformed to 4′‐hydroxy‐6,7‐dimethoxyisoflavone ( 3 ) and 2 to 4′‐hydroxy‐5,7‐dimethoxyisoflavone ( 4 ). This suggested that 1 and 2 were demethylated at the C‐4′ position with regioselectivity by Aspergillus niger. Copyright © 2006 Society of Chemical Industry     

Boron-doped hydrogenated amorphous carbon films grown by surface-wave mode microwave plasma chemical vapor deposition

We report the effects of boron (B) doping on optical and structural properties of the hydrogenated amorphous carbon thin films grown by surface-wave mode microwave plasma (SW-MWP) chemical vapor deposition (CVD) on n-type silicon and quartz substrates at room temperature. Argon and acetylene were used as a carrier and carbon source gases respectively. Analytical methods such as X-ray photoelectron spectroscopy (XPS), Nanopics 2100/NPX200 surface profiler, JASCO V-570 UV/VIS/NIR spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopy were employed to investigate the properties of the films. Low atomic concentration of B (0.08 at.%) was found in the doped film. The optical band gap of the undoped film was 2.6 eV and it decreased to 1.9 eV for the B-doped film. Structural property shows the crystalline structure of the film and it has changed after incorporating B as a dopant. The structural modifications of the films leading to being more graphite in nature were confirmed by the Raman and FT-IR characterization.     

Field test results of multi-channel digital tv transmission at 15 and 30 Mb/s through an intelsat satellite using a PSK/FDMA system

This paper describes field test results of multi-channel digital TV transmission using a PSK/FDMA system and the related subjective test results of received TV pictures. The picture quality of the multi-channel 15 or 30 Mb/s transmission for both NTSC and PAL systems through the INTELSAT POR satellite are subjectively evaluated for various bit-error rates. In addition, subjective evaluations were made at various values of earth-station e.i.r.p. to compare the picture quality of digital transmissions with that of current half-transponder FM transmission.     

Dynamic driving/braking force distribution in electric vehicles with independently driven four wheels

A novel algorithm for the dynamic driving/braking force distribution is proposed for electric vehicles (EV) with four in‐wheel motors. In such EVs, the vehicle lateral motion can be controlled by a yaw moment, generated by the torque difference between wheels. This method is known as DYC (Direct Yaw moment Control) in ordinary engine vehicle engineering; however, the torque difference can be generated more directly with in‐wheel motors. One problem of DYC is its instability on slippery roads, such as wet or snowy asphalt. To achieve high stability, the loads of wheels are preferably equal. The load on each wheel can be evaluated as the square root of the sum of squares of driving/braking force and side force. Therefore, the driving/braking forces, or motor torques, should be distributed depending on the side forces of the wheels, to minimize the load imbalance between wheels. The proposed algorithm can solve this optimization problem approximately with little calculation cost, and thus this method can be applied for real‐time calculation within a control period. Approximate solutions obtained with the proposed method are evaluated by comparison with numerical solutions that require much calculation time. The difference between these solutions is shown to be negligible, indicating the effectiveness of the proposed method. © 2001 Scripta Technica, Electr Eng Jpn, 138(1): 79–89, 2002     

Cost reduction of polycrystalline diamond compact bits through improved durability

This work reports the results of laboratory drilling tests conducted in order to measure improvements due to design and cutter modifications on PDC bits intended for use in geothermal well drilling. These tests, using 142.88 mm-dia. PDC full face bits, concentrated on improvements in bit life and cost performance. The tests were performed using granite drilling samples and a laboratory drilling machine at atmospheric conditions. The results from changes in bit and cutter shape are reported in the work.