Selective Ion Permeation Across Membranes Prepared from Steroidal Crown Ethers

Five crown ethers covalently-linked to the cholesterol skeleton were synthesized. Thermal analysis established that four of them have a cholesteric liquid-crystal phase. In particular, the monobenzo-13–crown-4 covalently-linked through an ethylene spacer to the cholesterol skeleton shows a stable cholesteric mesophase even at room temperature. The stable cholesteric mesophase at room temperature was also obtained by mixing two steroidal crown compounds. These mixed systems were embedded in a polymer matrix and the polymer/liquid-crystal composite membranes were subjected to ion-permeation experiments. It was found that the permeation selectivity is basically explained by the hole-size selectivity in the crown-metal interaction. In particular, composite membranes containing a monobenzo-13–crown-4 unit showed the remarkably high Li⁺ selectivity. It was concluded on the basis of examination of activation parameters that ion permeation occurs across channel-like stacks of crown ether rings.     

Report of two cases presenting with myelodysplastic syndrome during treatment of recurrent breast cancer

Two women with recurrent breast cancer presenting with myelodysplastic syndrome (refractory anemia) during chemotherapy were reported. At diagnosis of myelodysplastic syndrome, white blood cell count, hemoglobin and platelet count were 3,300/mm3, 4600/mm3, 5.5 g/dl, 6.3 g/dl, 1.1 x 10(4)/mm3 and 6.8 x 10(4)/mm3, respectively, in case 1 and 2. Bone marrow taps showed hypercellular marrows with dysplastic changes of erythrocytes, granulocytes and megakaryocytes in both cases. Before the occurrence of the myelodysplastic syndrome, both patients received various cytotoxic agents (mitomycin C: 77 mg, 108 mg; cyclophosphamide: 34,400 mg, 40,000 mg; doxorubicin: 340 mg, 460 mg; methotrexate: 410 mg, 700 mg; and vincristine: 9.5 mg, 14 mg, in case 1 and 2, respectively). One patient died 2 months after the onset of the myelodysplastic syndrome, and the other died 3 months after due to progression of metastatic breast cancer. Risk-benefits analysis of chemotherapy, especially adjuvant chemotherapy, should be performed in cases of breast cancer.     

Receiver sensitivity temperature dependence of small detectable area Hi-Lo germanium avalanche photodiode

Optical receiver sensitivity temperature dependence is measured in different detectable area (80, 30 ?m-diameter) Hi-Lo Ge APD modules at 450 Mbit/s bit rates. A 30 ?m-diameter device has a little power penalty against temperature increase compared with an 80 ?m-diameter device, with 2.4 dB receiver sensitivity improvement at 45°C.     

A Si bipolar 1.4-GHz time space switch LSI for B-ISDN

A 155-MB/s 32×32 Si bipolar switch LSI designed for wide application in the broadband ISDN was implemented. The operating speed is 1.4 GHz using an A-BSA Si bipolar process. Its throughput is 5.0 Gb/s by handling four 1.4-GHz interfaces, each of which supports an eight-channel multiplexed data stream. To realize a highly integrated high-speed bipolar LSI, power consumption and chip area should be reduced. Two technologies were developed for the LSI: (1) an active pull-down circuit with an embedded bias circuit in each gate, and (2) a modified standard cell with overlapped cell-channel structure. Using these technologies, total power consumption and chip area were reduced to 60% and 70%, respectively, of what is expected when conventional emitter-coupled logic (ECL) technologies and standard cell structures are used. The LSI evaluation results show that the developed LSI has sufficient performance to realize a large-scale B-ISDN switching system     

A real-time motion estimation and compensation LSI with wide searchrange for MPEG2 video encoding

This paper presents a motion estimation and compensation large scale integration (LSI) for the MPEG2 standard. An embedded RISC processor and special hardware modules enable the LSI to achieve a sufficient ability to perform real-time operation and provide the availability to realize many kinds of block matching algorithms. Using a three-step hierarchical telescopic search algorithm, a single chip accomplishes real-time motion estimation with search ranges of ±32.5×±32.5 pixels for motion vectors. The chip was fabricated using 0.5-μm CMOS technology and has an area of 16.5×16.5 mm² and 2.0 M transistors     

In situ observations of chemically induced grain-boundary migration and discontinuous precipitation in the aluminum-zinc system

In situ observations are reported for chemically induced grain-boundary migration (CIGM) and discontinuous precipitation (DP) in the Al-Zn system. In each case, it is found that the migration of the grain boundary is a steady continuous process, at least on the scale of the resolution of the electron optical techniques employed. However, there are significant differences; the grain-boundary velocities are such that a diffusion field must exist in the parent crystal for the case of CIGM but little or no volume diffusion penetration for steady DP. For CIGM, it is argued that the coherency strain energy in the diffusion field is sufficient for the development of a small residual chemical force; for steady DP, a large fraction of the total chemical force is available to act directly across the grain boundary. In the latter case, agreement is obtained between observed and calculated dynamic boundary shapes, using a method in which the chemical force (corrected for losses due to continuous precipitation in the parent phase) is balanced against capillary forces. Formerly with McMaster University     

Probabilistic distributions of pin gaps within a wire-spaced fuel subassembly and sensitivities of the related uncertainties to pin gap

Probabilistic fuel pin gap distributions within a wire-spaced fuel subassembly and sensitivities of the related uncertainties to fuel pin gaps are discussed. The analyses consist mainly of expressing a local fuel pin gap in terms of sensitivity functions of the related uncertainties and calculating the corresponding probabilistic distribution through taking all the possible combinations of the distribution of uncertainties. The results of illustrative calculations show that with the reliability level of 0.9987, the maximum deviation of the pin gap at the cladding hot spot of a center fuel subassembly is 8.05% from its nominal value and the corresponding probabilistic pin gap distribution is shifted to the narrower side due to the external confinement of a pin bundle with a wrapper tube.     

Hydrolysis mechanism of crosslinks formed between hydroxymethylated 2-substituted 4,6-diamino-s-triazines and cotton

Hydrolysis resistance and mechanism of reaction products of hydroxymethylated 2-substituted (X) 4,6-diamino-s-triazines (MXT) with cotton fabrics has been studied. Finishing reagents used were MXT having the following substituents: X = CH₃O? (MMT), (CH₃)₂CHO? (MIPT), CH₃? (MAG), C₂H₅NH? (MEM), HOC₂H₄NH? (MHEM), and (HOC₂H₄)₂N? (MBHEM). For comparison, trimethylolmelamine (TMM), dimethylolurea (DMU), dimethylolethyleneurea (DMEU), and dimethylol-ethyltriazone (DMET) were used. Hydrolysis was carried out in buffer and NaOH solutions of various pH's for 30 min at 80°C. The order of hydrolysis resistance of crosslinked reagents was determined from the nitrogen contents retained. It was as follows: pH 1, MROT < MRNT < MRT; pH ≧ 2, MROT > MRT > MRNT; pH ≦ 13, MROT > MRNT; pH 14, MROT < MRT < MRNT, where MROT is hydroxymethylated 2-alkoxy (MMT, MIPT), MRT is hydroxymethylated 2-alkyl (MAG), and MRNT is hydroxymethylated 2-alkylamino-4,6-diamino-s-triazine (MEM, MHEM, MBHEM). This fact can be explained in terms of the basicity constant (p^K_b) of crosslinked MXT with cotton (approximately p^K_b) of 2-substituted 4,6-diamino-s-triazine (XT). The hydrolysis rates of crosslinked MMT, MAG, and MEM were determined at pH 2. The activation energies were 21.8 for MMT, 20.9 for MAG, and 21.0 kcal/mole for MEM.