The Reaction of Alkynes with Model Gold Catalysts: Generation of Acetylides,Self-coupling and Surface Decomposition

Catalysis Letters - Alkynes are one of the most important groups of building blocks in organic chemistry as they work as nucleophiles upon deprotonation of its acidic hydrogen. On the surface of a...     

Space charge behavior in polymer film based on increment of capacitance under AC high field

Polymer materials have excellent dielectric and insulation properties; however, those properties in AC high field region have not been known well. Recently we established an evaluation method of high‐field AC dissipation current waveform of polymer materials 1 . AC dissipation current waveforms of polyethylene and polypropylene films show nonlinear distortion in AC high‐field region. This nonlinearity was thought to be related to the behavior of AC space charge formation in the sample near electrodes. The properties of space charge formed under AC high field at power frequency seem to differ from those formed under DC high field. The measurement of AC space charge distribution is not so easy due to the resolution limit of the space charge measurement. We studied the dielectric properties of biaxially oriented polypropylene (BOPP) film under AC high field up to 120 °C. It was found that tan δ, AC dissipation current (Ixr), and unbalanced component of capacitive current (ΔIxc) increased when the temperature became higher. In particular, ΔIxc increased above some threshold field and was considered to be due to the AC space charge formation. This AC space charge layer near electrode is thought to be formed due to carrier injection under AC high‐field application. Usually, the carrier mobility becomes smaller on lowering the temperature. Most of the carriers injected from the electrode are trapped near the electrode in the sample film. But in the high‐temperature region, the carrier mobility becomes larger and the carrier injection starts to increase from lower field. Many more carriers are injected from the electrode. It is thought that some of the injected carriers are trapped inside the sample film; the others go through the sample to the opposite side. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 141(2): 8–16, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10018     

Recombinant scrapie-like prion protein of 106 amino acids is soluble

The N terminus of the scrapie isoform of prion protein (PrPSc) can be truncated without loss of scrapie infectivity and, correspondingly, the truncation of the N terminus of the cellular isoform, PrPC, still permits conversion into PrPSc. To assess whether additional segments of the PrP molecule can be deleted, we previously removed regions of putative secondary structure in PrPC; in the present study we found that deletion of each of the four predicted helices prevented PrPSc formation, as did deletion of the stop transfer effector region and the C178A mutation. Removal of a 36-residue loop between helices 2 and 3 did not prevent formation of protease-resistant PrP; the resulting scrapie-like protein, designated PrPSc106, contained 106 residues after cleavage of an N-terminal signal peptide and a C-terminal sequence for glycolipid anchor addition. Addition of the detergent Sarkosyl to cell lysates solubilized PrPSc106, which retained resistance to digestion by proteinase K. These results suggest that all the regions of proposed secondary structure in PrP are required for PrPSc formation, as is the disulfide bond stabilizing helices 3 and 4. The discovery of PrPSc106 should facilitate structural studies of PrPSc, investigations of the mechanism of PrPSc formation, and the production of PrPSc-specific antibodies.     

The effects of FR167653 in extended liver resection with ischemia in dogs

PURPOSE: We assess the neovascularity of clinically localized prostate cancer by immunohistochemistry using the monoclonal antibody CD34 in an attempt to identify associations between angiogenesis and disease progression following radical prostatectomy. MATERIALS AND METHODS: Microvascularity was evaluated using the CD34 monoclonal antibody in archival paraffin embedded radical prostatectomy specimens from 149 patients followed from 3 to 10 years (mean 6.6). Vessels were quantified by counting a minimum of 2 selected microscopic fields (200x, 0.754 mm.2) from each tumor, area of prostatic intraepithelial neoplasia and prostatic hyperplasia, and given a numerical value representing the microvessel density count. RESULTS: Mean microvessel density count did not vary significantly with age or race. There was a significant association between the count and nuclear grade, Gleason sum and pathological stage. Cox survival analysis shows that microvessel density is significantly related to time to recurrence when considered as a continuous variable (p=0.03) as well as dichotomous variable (p=0.007) (microvessel density count less than 90 and 90 or greater). The 5-year recurrence-free survival was significantly higher for patients with a count less than 90 (71%) than for those with a count 90 or greater (51%) (p=0.006). The 5-year recurrence-free survival was also significantly different when microvessel density was used as a continuous variable (p=0.02). Controlling for stage, Gleason sum, race and nuclear grade, microvessel density remained significant in predicting recurrence (p=0.03) but when pretreatment prostate specific antigen was included in the model the count was no longer significant. The microvessel density count in the tumor area significantly increased with increasing Gleason sum and nuclear grade but it did not increase significantly in the adjacent benign prostate or areas of prostatic intraepithelial neoplasia in the same specimen. CONCLUSIONS: Microvascularity or neovascularity as measured by the CD34 antigen may be a prognostic marker of recurrence for prostate cancer patients after radical prostatectomy but more study in prostate specific antigen era patients with sufficient followup is needed.     

Characteristics of a small planar loop antenna

Small planar-type loop antennas used in pagers have fixed directivity patterns. As a result, the received signal strength depends on the orientation of the antenna. A new type of small planar loop antenna (PLA) is, therefore, proposed. The position of the conductor posts can be changed and MOSFETs are adopted for switching the conductor posts. If the positions of the posts can be switched at will, then the dependence of the received signal on the orientation of the antenna can be minimized. Fundamental experiments were performed in order to investigate the characteristics of polarization switching. Polarization directivity was measured while switching each conductor alternately. The receiving characteristics are affected by a cable connected to the receiver. Therefore, the transmission characteristics are measured by using an internal oscillator. As a result, meaningful results were obtained and the possibility of polarization diversity was shown     

Photonic generation of millimetre- and submillimetre-waves using rectangular-waveguide-output uni-travelling-carrier photodiode module

The generation of millimetre- and submillimetre-waves by uni-travelling-carrier photodiode module with WR-8 output port is investigated in a frequency range of up to 800 GHz. A steep decrease of the output power with increasing frequency is observed, implying that an additional loss in the electrical waveguide has a considerable influence.     

Continuous intra-arterial infusion therapy via the occiptial artery for head and neck tumors: second choice treatment

We report three cases in which continuous intra-arterial infusion therapy via the occipital artery was combined with radiotherapy for head and neck tumors. An angiographic catheter was inserted into the feeding artery of the tumor retrogradely via the occipital artery under fluoroscopic guidance. Patients treated were maxillary sinus cancer, tongue cancer and hemangiosarcoma. No complications occurred due to this procedure in any of the three patients. This procedure was considered very useful when the approach from the superficial temporal artery was not possible due to prior treatment.     

Purification and characterisation of antioxidative peptides from unfractionated rice bran protein hydrolysates

Crude rice bran protein (CRBP) was prepared by alkaline extraction and then treated with 0.6 m HCl to remove phytic acid. The phytate‐free rice bran protein (PFRBP) was hydrolysed with proteases M, N, S, P and pepsin under optimal conditions. Hydrolysates obtained from various hydrolysis periods were subjected to analysis for their degree of hydrolysis (DH) and functional properties. The hydrolysates were fractionated by reversed‐phase column chromatography on Kaseigel ODS resin (120–140 μm) using a stepwise gradient of aqueous ethanol, and their activities were measured. The 40% ethanol fraction of protease P 4 h‐hydrolysate was separated by successive reversed‐phase high‐performance liquid chromatography and the amino acid sequences of isolated antioxidative peptides were determined by a protein sequencer and matrix‐assisted laser desorption ionisation‐time of flight mass spectrometry. Crude rice bran protein had higher antioxidative activity than PFRBP, due to the presence of phytic acid. Phytate contents of rice bran, CRBP and PFRBP were 2.5%, 1.42% and 0%, respectively. The activity of PFRBP increased upon protease digestion. Protease M hydrolysates showed the highest DH, but the lowest antioxidative activity. Hydrolysates with DH below 10% had higher antioxidative activity than those above 20%. This result indicates that the antioxidative activity of the hydrolysates is inherent to their characteristics amino acid sequences of peptides depending on the protease specificities.     

Comparison of carbonaceous aerosols in Tokyo before and after implementation of diesel exhaust restrictions

We compared the status of carbonaceous aerosols in Tokyo before and after the implementation of a diesel vehicle regulation intended to reduce the quantity of particulate carbon from diesel engines in one of the largest scale ever attempts at vehicle exhaust control. Radiocarbon (14C) in elemental carbon (EC) and total carbon (TC) were analyzed to identify fossil fuel carbonaceous particles emitted from diesel-powered vehicles. One-sided paired-month t-tests showed no distinct difference in the absolute concentrations of particles in terms of total mass (19.5 to 18.0 microg m(-3); p = 0.321), EC (3.6 to 3.3 microg m(-3); p = 0.272), and TC (6.3 to 6.2 microg m(-3); p = 0.418) for the finest particles (d(a) < 1.1 microm) after the implementation of the regulation. The ratios of the concentrations of the chemical constituents were, however, altered after the regulation. EC/TC was significantly decreased from 56.7% to 50.2% (p = 0.039). Although it was not statistically significant, the percentage of fossil carbon in EC also decreased (67.8% to 63.8%; p = 0.104). Since EC is predominantly of combustion origin, the observed decrease was likely due to the decrease in fossil EC emissions from diesel-powered vehicles. The decrease in EC/TC after the implementation of the regulation was also likely to have resulted from attachment to diesel vehicle exhaust systems of particulate filters as required as part of the regulation by the Tokyo Metropolitan Government. The EC/TC of fossil carbon of the finest particles decreased from 66.2% to 55.2% (p = 0.066), but EC/TC of biomass carbon did not decrease but rose slightly from 43.6% to 44.5% (p > 0.5). Thus, the relative ratios of components of carbonaceous aerosol particles, such as 14C, could provide a better understanding of the atmospheric pollution status, despite short-term fluctuations, than do measurements of absolute concentrations.