Fabrication of three‐dimensionally ordered microporous membrane by wet phase separation

We report a novel porous fluorinated polyimide membrane with a cylinder structure fabricated by a wet phase inversion process, which is formed by a ternary system, polyimide/solvent/water. The porous polyimide membranes consisted of a thin top porous layer and three‐dimensionally ordered cylinder micropores. The porous membrane‐forming solvents were N‐methylpyrrolidone containing nonsolvent additives such as alcohol, and the height and width of the cylinder structure were controlled by the solvents. Water fluxes through the porous polyimide membranes were measured using a stirred dead‐end filtration cell, and the fluxes of the porous membrane with the cylinder‐type structure were approximately three times greater than those of the membrane with the finger‐type structure. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3016–3021, 2004     

Dehydrogenative polycondensation of telechelically bis(dimethylsilyl)functionalized oligo(dimethylsiloxane)s or aromatics and 1,3,3,5,5,7,7,7-octamethyltetrasiloxane

Telechelically bis(hydrodimethylsilyl)-functionalized oligo(dimethylsiloxane)s or aromatics were found to give polymers constituting of alternating disilylene and oligodimethylsiloxane or 4,4′-diylaromatics as repeating units by dehydrogenative coupling reaction in the presence of palladium dibenzylideneacetone complex. The same catalyst gave polysilylenes with trisiloxane pendant from 1,1-dihydro-1,3,3,5,5,7,7,7-octamethyltetrasiloxane. Received: 18 October 1996/Accepted: 31 October 1996     

Repeatable change in electrical resistance of Si surface by mechanical and electrical nanoprocessing

The properties of mechanically and electrically processed silicon surfaces were evaluated by atomic force microscopy (AFM). Silicon specimens were processed using an electrically conductive diamond tip with and without vibration. After the electrical processing, protuberances were generated and the electric current through the silicon surface decreased because of local anodic oxidation. Grooves were formed by mechanical processing without vibration, and the electric current increased. In contrast, mechanical processing with vibration caused the surface to protuberate and the electrical resistance increased similar to that observed for electrical processing. With sequential processing, the local oxide layer formed by electrical processing can be removed by mechanical processing using the same tip without vibration. Although the electrical resistance is decreased by the mechanical processing without vibration, additional electrical processing on the mechanically processed area further increases the electrical resistance of the surface.     

Adhesion improvement of HIVIPP C targets on Au backings

Accurate measurement of the cross-section of the ¹²C(α, γ)¹⁶O reaction is very important in nuclear astrophysics. Enriched ¹²C targets prepared with the high energy vibrationl powder plating [HIVIPP] method for this purpose have been used successfully. Initially, however, the ¹²C deposits for studying this small cross-section partially peeled from their Au backings when irradiated with beam currents≥2 times the 7 μA pulsed α-beam used previously. This problem was solved when the amorphous ¹²C powders were converted to graphite by heat-treatment in a high-temperature furnace. We investigated powder heat treatments at temperatures of 2600-3500 °C to reveal, which conditions resulted in uniform and highly adhesive depositions on Au backings.     

Feasibility study on 1.6 μm continuous-wave modulation laser absorption spectrometer system for measurement of global CO2 concentration from a satellite

A feasibility study is carried out on a 1.6 μm continuous-wave modulation laser absorption spectrometer system for measurement of global CO(2)concentration from a satellite. The studies are performed for wavelength selection and both systematic and random error analyses. The systematic error in the differential absorption optical depth (DAOD) is mainly caused by the temperature estimation error, surface pressure estimation error, altitude estimation error, and ON wavelength instability. The systematic errors caused by unwanted backscattering from background aerosols and dust aerosols can be reduced to less than 0.26% by using a modulation frequency of around 200 kHz, when backscatter coefficients of these unwanted backscattering have a simple profile on altitude. The influence of backscattering from cirrus clouds is much larger than that of dust aerosols. The transmission power required to reduce the random error in the DAOD to 0.26% is determined by the signal-to-noise ratio and the carrier-to-noise ratio calculations. For a satellite altitude of 400 km and receiving aperture diameter of 1 m, the required transmission power is approximately 18 W and 70 W when albedo is 0.31 and 0.08, respectively; the total measurement time in this case is 4 s, which corresponds to a horizontal resolution of 28 km.     

Significance of the detection of staphylococcal enterotoxin A gene in low fat milk which caused a serious outbreak of food poisoning

In June 2000, there was a large-scale outbreak of food poisoning after consumption of Snow Brand low fat milk. In the evening of a day the incident made public, some cartons of low fat milk were brought to our laboratory for examination. Next day, we detected only staphylococcal enterotoxin (SE) A gene among SE (A-E) genes by PCR in left-over milk samples or samples from the same lots that patients had consumed. We presumed that the outbreak was caused by the intake of SEA. We subsequently confirmed the presence of SEA in these samples. To investigate the existence of SE (A-E) genes in milk, we examined 100 samples of commercial low fat milk and milk by PCR, but none of the genes was detected. We estimated the detection limit of SEA gene in low fat milk by PCR. Four strains of SEA-producing Staphylococcus aureus cultures were serially diluted in low fat milk. The SEA gene was detected at levels of 5.5 x 10(2) to 1.6 x 10(4) cfu/mL of S. aureus. These amounts of S. aureus are higher than the values in raw milk reported previously. Therefore we consider that SE genes in low fat milk should usually be undetectable by our PCR. This study shows that quick detection of SE genes by PCR is very helpful to analyze outbreaks, especially if no significant bacterium can be cultured.     

Involvement of Ras in Bruton's tyrosine kinase-mediated JNK activation

Defects in Bruton's tyrosine kinase (Btk) result in B cell immunodeficiencies in humans and mice. Recent studies showed that Btk is required for maximal activation of JNK, a family of stress-activated protein kinases, induced by several extracellular stimuli including interleukin (IL)-3. On the other hand, IL-3-induced JNK activation is dependent on Ras. In the present study we have investigated whether Ras is involved in Btk-mediated JNK activation in BaF3 mouse pro-B cells. Overexpression of wild-type Btk protein in these cells enhanced JNK activation upon IL-3 stimulation, whereas expression of kinase-dead Btk partially suppressed JNK activation. Induced expression of the dominant negative Ras(N17) in the cells overexpressing wild-type Btk suppressed JNK activation. Importantly, overexpression of Btk enhanced the level of the GTP-bound, active form of Ras in response to IL-3 stimulation. Btk overexpression also increased the Shc-Grb2 association induced by IL-3 stimulation. Expression of either N17Ras or V12Ras did not impose any effects on Btk kinase activity. These data collectively indicate that Ras plays a role of an intermediary signaling protein in Btk-mediated JNK activation induced by the IL-3 signaling pathway.     

A mesenchymal malignant mesothelioma that changed from mixed type to purely sarcomatous type]

STUDY OBJECTIVE: To evaluate the long-term efficacy of laparoscopic Burch urethropexy. DESIGN: Pilot study. SETTING: Private practice. PATIENTS: Thirty-five consecutive women (average age 45.5 yrs, average parity 2.3, average weight 67.7 kg) treated for genuine stress incontinence between May 1992 and July 1994. INTERVENTIONS: Urethropexy was performed with curved needle suturing in 7 women, straight needle suturing in 5, and Stamey needle suturing in 23. Twenty-five (71.4%) patients had concomitant pelvic surgery. MEASUREMENTS AND MAIN RESULTS: Wilcoxon two-sample, chi2, and Fisher's exact tests were performed to determine which variables were significantly associated with surgical success. Average operating time was 190 minutes, hospitalization 24 hours, and catheterization 5 days. The cure rate of stress incontinence was 89% 3 months and 86% 1 year after surgery. At average follow-up of 34 months, only 68.6% of patients reported complete or almost complete cure, 11.4% were improved, and 20% were complete failures. The only operative variable approaching statistical significance for predicting surgical success was type of suture needle (p = 0.07), with the Stamey needle group having the highest cure rate. Women who were cured or almost cured had a significantly shorter follow-up than those who were improved or failures (p = 0.001). CONCLUSION: The success rate of laparoscopic Burch urethropexy compares with that of open Burch procedure at 1 year, but drops considerably thereafter.