Selective hydrolysis of polyunsaturated fatty acid-containing oil withGeotrichum candidum lipase

Polyunsaturated fatty acids (PUFA), especially docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), can be concentrated in glycerides by hydrolyzing tuna oil withGeotrichum candidum lipase, the main components in the resulting oil being triglycerides. The reaction mechanism of this selective hydrolysis was investigated. Although the lipase acted well on the esters of oleic, linoleic, and α-linolenic acids, it did not affect the esters of γ-linolenic acid, arachidonic acid, EPA, and DHA as much. The action of PUFA-glycerides was mono-> di- > triglycerides. Furthermore, the condensation of PUFA-partial glycerides and PUFA occurred even in the presence of a large amount of water, and the partial glycerides converted to the triglycerides by transacylation. These results suggested that the PUFA-rich triglycerides were accumulated in the glyceride fraction by the following mechanism: The PUFA-partial glycerides generated by the hydrolysis were converted to PUFA-triglycerides by condensation and transacylation reactions. As the PUFA-triglycerides formed were the poor substrates of lipase, they were accumulated in the reaction mixture.     

Production of structured lipids containing essential fatty acids by immobilizedRhizopus delemar lipase

An attempt was made to produce structured lipids containing essential fatty acid by acidolysis with 1,3-positional specificRhizopus delemar lipase. The lipase was immobilized on a ceramic carrier by coprecipitation with acetone and then was activated by shaking for 2 d at 30°C in a mixture of 5 g safflower or linseed oil, 10 g caprylic acid, 0.3 g water and 0.6 g of the immobilized enzyme. The activated enzyme was transferred into the same amount of oil/caprylic acid mixture without water, and the mixture was shaken under the same conditions as for the activation. By this reaction, 45–50 mol% of the fatty acids in oils were exchanged for caprylic acid, and the immobilized enzyme could be reused 45 and 55 times for safflower and linseed oils, respectively, without any significant loss of activity. The triglycerides were extracted withn-hexane after the acidolysis and then were allowed to react again with caprylic acid under the same conditions as mentioned above. When acidolysis was repeated three times with safflower oil as a starting material, the only products obtained were 1,3-capryloyl-2-linoleoylglycerol and 1,3-capryloyl-2-oleoyl-glycerol, with a ratio of 86∶14 (w/w). Equally, the products from linseed oil were 1,3-capryloyl-2-α-linolenoyl-glycerol, 1,3-caprylol-2-linoleoyl-glycerol, and 1,3-capryloyl-2-oleoly-glycerol (60∶22∶18, w/w/w). All fatty acids at the 1,3-positions in the original oils were exchanged for caprylic acid by the repeated acidolyses, and the positional specificity ofRhizopus lipase was also confirmed to be strict.     

Dynamic percolation phenomenon of poly(methyl methacrylate)/surface fluorinated carbon black composite

The electrical resistivity of polymer filled with conductive filler, such as carbon black (CB) particles, is greatly decreased by incorporating the conductive filler. This is called the percolation phenomenon and the critical CB concentration is called the percolation threshold concentration (Φ*). For CB particle–filled insulating polymer composite at lower than Φ*, the conductive CB network is constructed in the polymer matrix when the composite is maintained at a temperature higher than the glass‐transition temperature or the melting temperature of the polymer matrix. This phenomenon is called dynamic percolation and the time to reach the substantial decrease in resistivity is called percolation time (t_p). To investigate the relationship between the dynamic percolation process and the surface state of CB particles, we used three kinds of carbon black particles such as original carbon black (CB0) and fluorinated carbon black (FCB010 and FCB025)–filled poly(methyl methacrylate) (PMMA). It was observed that the dynamic percolation curves for CB0‐filled PMMA and FCB‐filled PMMA composites shifted to a shorter percolation time with increases in both the annealing temperature and the filler concentration. However, the dynamic percolation curves of FCB‐filled PMMA showed a gradually decreasing trend compared to that of CB0‐filled PMMA composites. The activation energy calculated from an Arrhenius plot of the t_p against the inverse of the annealing temperature was decreased by surface fluorine treatment. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1151–1155, 2003     

Structure and properties of highly stereoregular isotactic poly(methyl methacrylate) and syndiotactic poly(methyl methacrylate) blends treated with supercritical CO2

The structure and properties of highly stereoregular isotactic poly(methyl methacrylate) (it-PMMA) and syndiotactic poly(methyl methacrylate) (st-PMMA) blends with crystalline stereocomplex formed by supercritical CO₂ treatment at temperatures ranging from 35 to 130 °C were investigated by means of differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), and dynamic mechanical analysis (DMA) measurements. The melting temperature, T_m, and the heat of fusion, ΔH_m, had maximum values at about 200 °C and 25 J/g, respectively. The degree of crystallinity evaluated by WAXD ranged in value from 32 to 38%. The fringed-micellar stereocomplex crystallites were formed in case of treatment temperatures below 90 °C, and the orderliness perpendicular to the helix axis of the fringed-micellar crystallites was considered to be increased with increasing treatment temperature. In case of treatment temperature of 130 °C, the fringed-micellar crystallites and the lamellar crystallites with high orderliness parallel to the helix axis coupled with the perpendicular orderliness were formed, and the respective double endothermic peaks, T_m¹ and T_m³, were observed in DSC due to the melting of the two kinds of stereocomplex crystallites. The it-PMMA/st-PMMA blends containing the fringed-micellar crystallites maintained high values of storage modulus, E′, up to higher temperature compared with the amorphous blends. The E′ of the blend treated with CO₂ at 130 °C decreased twice at temperatures corresponding to T_m¹ and T_m³.     

Characteristics of an actuator-driven pulsed water jet generator to dissecting soft tissue

This paper reports characteristics of an actuator-driven pulsed water jet generator applied, in particular, to dissect soft tissues. Results of experiments, by making use of high speed recording of optical visualization and varying nozzle diameter, actuator time interval, and their effects on dissection performance are presented. Jet penetration characteristics are compared with continuous water jet and hence potential assessment of pulsed water jets to clinical applications is performed.     

Effects of Bearing Type on Seismic Response of Small Base Isolation System Using Friction Bearings

In this study, dynamic characteristics of the small base isolation system using new friction bearings are investigated by excitation experiment, and compared to other one using previous bearings. Peak amplitude of the acceleration response waves on the small base isolation system is decreased to about 10%-25% compared to the input waves. Also root mean square amplitude is decreased to about 10%-40%. In case of the ball embedded a cylindrical sponge, the new bearing, the damping ratio increases with increasing width of the cylindrical sponge. The natural frequency does not change. On the other hand, in case of the marble plate that is previous bearing, the damping ratio increases with increasing curvature radius of the marble plate, the natural frequency also increases. Therefore, the small base isolation system using new friction bearing provides better performance. The responses of the base isolation system indicate nonlinier effects by friction force.     

Carrier separation analysis for clarifying carrier conduction and degradation mechanisms in high-k stack gate dielectrics

The carrier conduction and the degradation mechanism in n⁺gate p-channel metal-insulator-semiconductor field-effect-transistors with HfAlO_X (Hf: 60 at.%, Al: 40 at.%)/SiO₂ dielectric layers have been investigated using carrier separation method. Since gate current depends on substrate bias and both electron and hole currents are independent of temperature over the range of 25–150 °C, the conduction mechanism for both currents is controlled by a tunneling process. As the interfacial SiO₂ layer (IL) thickness increases in a fixed high-k layer thickness (T_high-k), a dominant carrier in the leakage current changes from hole to electron around 2.2-nm-thick IL. This is due to an asymmetric barrier height for electrons and holes at the SiO₂/Si interface. On the contrary, in the case of a fixed IL thickness of 1.3 nm, the hole current is dominant in the leakage current, regardless of T_high-k. It is shown that the dominant carrier in the leakage current depends on the structure of the high-k stack. Both electron and hole currents for the stress-induced-leakage-current (SILC) state increase slightly relative to the initial currents, which means that the trap generation in the high-k stack occurs near both the conduction band edge of n⁺poly-Si gate and the valence band edge of Si substrate. The electron current at soft breakdown (SBD) state dramatically increases over that for the SILC state, while the hole currents for both the SILC state and SBD are almost the same. This indicates that the defect sites generated in the high-k stack after SBD are located at energies near the conduction band edge of n⁺poly-Si gate. Both the defect generation rate and the defect size in the HfAlO_X/SiO₂ stacks are large compared with those in SiO₂. It is inferred that, in high-k dielectric stack, the defect generation mainly occurs in the high-k side rather than the IL side, and the defect size larger than the case of SiO₂ could be related to a larger dielectric constant of the high-k layer.     

Apoptosis in labial salivary glands from Sj?gren''s syndrome (SS) patients: comparison with human T lymphotropic virus-I (HTLV-I)-seronegative and -seropositive SS patients

Patients with solitary rectal ulcer syndrome (SRUS) frequently present with a mass that can be misinterpreted as cancer. In contrast, the occurrence and characteristics of SRUS-like histopathology produced by underlying malignancy have not been reported in detail. We report seven patients whose rectal mass that was induced by infiltrating carcinoma showed only histopathologic changes of SRUS on initial mucosal biopsy specimens. Carcinoma was evident in subsequent specimens after one to five repeat biopsies with delay in diagnosis from 1 week to 18 months in six patients. In one patient, infiltrating carcinoma was suggested on the first biopsy specimen by immunohistochemistry for cytokeratin. Three of the patients had primary rectal adenocarcinoma, two had metastatic carcinoma from stomach or ovary, and two had direct invasion of anal squamous cell carcinoma or prostatic adenocarcinoma. We conclude that the histopathology of SRUS may occasionally represent a characteristic but nonspecific mucosal reactive change to a deeper seated malignancy. The terminology "solitary rectal ulcer syndrome/mucosal prolapse changes" with a cautionary note may be useful for reporting biopsy results to emphasize the possibility of underlying primary or metastatic malignancy in the differential diagnosis.     

Microscopic observations and inflammatory cytokine productions of human macrophage phagocytising submicron titanium particles

This study was performed to microscopically observe and measure inflammatory cytokine production by human macrophages phagocytosing submicron titanium (Ti) particles. Observations with secondary electron microscopy (SEM), SEM/electron probe microanalysis (EPMA) and transmission electron microscopy (TEM) indicated that macrophages [phorbol-12-myristate-13-acetate (PMA)-differentiated THP-1 cells] at 24 h in culture actively phagocytosed and accumulated submicron Ti particles in intracellular phagosomes, in which refinement of Ti particles occurred. The macrophages were also cultured for 24 h in four media with and without submicron Ti particles and lipopolysaccharide (LPS; components of bacteria). Whilst neither stimulus reduced cell viability, submicron Ti particles and LPS activation independently and synergistically caused the macrophages to produce three inflammatory cytokines (TNF-α, IL-1β and IL-6) at high levels in the culture supernatants. The inflammatory and osteolysis conditions caused by macrophages phagocytosing submicron Ti particles would be worsened by challenge with LPS in patients wearing Ti prostheses.     

Cathode catalysts for fuel cell development: A theoretical study based on band structure calculations for tungsten nitride and cobalt tungsten nitrides

Band structure calculations were performed for tungsten nitride, cobalt tungsten nitrides, and platinum slabs. The major requirements for the development of a superior cathode catalyst are: (1) that the Fermi level of the cathode catalyst is close to the energy level of the lowest unoccupied molecular orbital of O₂, the lowest unoccupied atomic orbital of an oxygen atom, and the lowest unoccupied atomic orbital of a hydrogen atom so that they can readily interact with one another; and (2) that the cathode catalysts have smaller ΔE value which represent the difference between the Fermi level and the peak position of the density of states of the O_p orbital of O₂ adsorbed on the catalyst. The active site structures of cobalt tungsten nitrides for activation of the oxygen reduction reaction were found to have the surface structure of Co–O–Co, which lowered the unoccupied orbital of the oxygen atom to approximately that of the Fermi level. However, this structure concomitantly lowered the Fermi level, which resulted in an increase in ΔE. Consequently, the optimal cathode catalyst regarding the surface conformation contains a Co–O–Co structure that is dispersed on the surface of the cobalt tungsten nitride. The cobalt tungsten oxynitride exhibited a catalytic activity for the oxygen reduction reaction. A linear dependence is observed between the ΔE and the oxygen reduction reaction offset potentials of the tungsten nitride, cobalt tungsten nitride, cobalt tungsten oxynitride, and platinum.