Ion beam modification of ePTFE for improving the blood compatibility

Expanded polytetrafluoroethylene (ePTFE), which is a durable biomaterial because of its excellent biological inertness, is now widely used for prostheses in clinical medicine. However, conversely, the inert nature of ePTFE results in poor adaptability to the surrounding tissue due to lack of a cell-adhesive property. In this study, the surface of ePTFE was modified with ion beam irradiation to improve the blood compatibility. The surface modification of ePTFE sheets by He⁺, Ne⁺, Ar⁺ and Kr⁺ ion beams was performed at an energy of 150 keV with fluences of 1 × 10¹⁴, 5 × 10¹⁴ and 1 × 10¹⁵ ions/cm². To investigate anti-thrombogenicity, Ca²⁺-replenished platelet-rich plasma (PRP) was placed in contact with the surfaces for 10 min. Compared to the non-modified ePTFE surface, platelet response was inhibited on the surfaces modified with He⁺, Ne⁺ and Ar⁺: 5 × 10¹⁴ and 1 × 10¹⁵ ions/cm², and Kr⁺: 5 × 10¹⁴ ions/cm²; however, platelet response was promoted on the surfaces modified with He⁺, Ne⁺ and Ar⁺: 1 × 10¹⁴ ions/cm², and Kr⁺: 1 × 10¹⁴ and 1 × 10¹⁵ ions/cm². The significant morphological changes in ePTFE surface associated with ion beam modification are thought to be one of the reasons for the inhibition of platelet response. Endothelial cells were cultured on the surfaces for 3 days to evaluate the cellular response. Endothelial cell growth was significantly promoted on all of the surfaces of ion beam-modified ePTFE, although the non-modified ePTFE surface dramatically inhibited this growth. It is concluded that ion beam modification of ePTFE surface can improve the blood compatibility through not only the promotion of endothelial cell growth but also the inhibition of platelet response.     

In situ binary sol–gel reaction of various trifunctional alkoxysilane in the silane‐grafted polyolefin matrix and its effect upon the mechanical properties

The vinyltrimethoxysilane‐grafted ethylene‐propylene copolymer/trifunctional methoxysilane (EPR‐g‐VTMS/RTMS) composites were prepared via in situ silica sol–gel reactions. Five trifunctional methoxysilane compounds (n‐hexyltrimethoxysilane, n‐decyltrimethoxysilane, n‐tetradecyltrimethoxysilane, n‐octadecyltrimethoxysilane, and phenyltrimethoxysilane) have been selected for this study. The water‐cross‐linked EPR‐g‐VTMS/RTMS composites were characterized by attenuated total reflectance‐Fourier transform infrared spectroscopy, gel content, solid‐state ²⁹Si CP/MAS NMR, wide‐angle x‐ray scattering, tensile strength, and field emission scanning electron microscopy measurements. The type of RTMS additive has a substantial influence on the nature of siloxane band networks and eventually the mechanical tensile properties. This finding suggests that the interaction and/or entanglement between the EPR‐g‐VTMS matrix and the substituent of the RTMS additives are crucial for the modifying mechanical properties. Moreover, for the water‐cross‐linked EPR‐g‐VTMS/CnTMS (n = 6, 10, 14, and 18) composites, the joint evidence provided by attenuated total reflectance‐Fourier transform infrared spectroscopy, ²⁹Si CP/MAS NMR, and wide‐angle x‐ray scattering results suggested the formation of ladder‐type poly(n‐alkyl silsesquioxane)s and the presence of the highly ordered structure with a thickness equal to the length of two n‐alkyl groups in all‐trans conformation. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers.     

Fabrication of nanostructured polycarbonate/poly(methyl methacrylate) blends with improved optical and mechanical properties by high‐shear processing

The structure and properties of polycarbonate (PC)/poly(methyl methacrylate) (PMMA) blends fabricated using a high‐shear extruder at different shear rates were investigated. It was found that the morphologies of the blends were greatly dependent on the shear rate exerted during melt processing. High‐shear processing leads to a nanostructured PC/PMMA blend, in which PMMA domains with a size of less than 50 nm are homogeneously dispersed in the PC matrix. The prepared nanostructured blends exhibit not only excellent optical properties with a transmittance of more than 90% in the visible region but also a higher modulus than pure PC. In contrast, the PMMA domain size ranges from submicron to micrometer for the same blends processed at a low‐shear rate. These blends are opaque and display much lower elongation at break compared with the blends processed at a high‐shear rate. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

层层自组装法制备碳纳米管薄膜研究进展

综述了近年来通过层层自组装法制备碳纳米管薄膜的一些最新研究进展,重点介绍了通过物理吸附和化学吸附两种方式来制备碳纳米管组装膜,并对如何提高碳纳米管薄膜的电化学稳定性方面进行了论述。     

Characterization and CO2 sorption properties of poly[methacryloxypropylheptacyclopentyl‐T8‐silsesquioxane‐ co‐3‐methacryloxypropyltris(trimethylsiloxy)silane]

Poly[methacryloxypropylheptacyclopentyl‐T8‐silsesquioxane (MAPOSS)‐co‐3‐methacryloxypropyltris(trimethylsiloxy)silane (SiMA)] was synthesized through free radical polymerization. The physical and carbon dioxide (CO₂) sorption properties of the copolymer membranes were investigated in terms of the MAPOSS content. As the MAPOSS content increases, the membrane density increased, suggesting a decrease in the fractional free volume. In addition, the thermal stability was improved with increasing the MAPOSS content. These are because of the polyhedraloligomericilsesquioxane (POSS) units that restrict the high mobility of poly(SiMA) segments. The glass transition temperature, T_g of the copolymers was single T_g based on the differential scanning calorimetry, suggesting that the copolymers were random and not phase separation. Based on the CO₂ sorption measurement, the POSS units play a role in reducing Henry's dissolution by suppressing the mobility of the poly(SiMA) component, while POSS units increase the nonequilibrium excess free volume, which contributes to the Langmuir dissolution. Based on these results, the introduction of MAPOSS unit is one of the effective ways to improved the thermal stability and CO₂ sorption property due to the enhancement of the polymer rigidity. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Electrical Properties of Pre-Alloyed Cu-P Containing Electrically Conductive Adhesive

In this study, a pre-alloyed Cu-P powder with a trace amount of P (0.002 at.%) was used as a metallic filler in a phenolic resin-based electrically conductive adhesive (ECA). The electrical property of the Cu-P-filled ECA was investigated for long-term stability and reliability by aging at high temperature exposure at 125°C and 85°C/85% RH for 1000 h, respectively. Results showed that the electrical resistivity of the Cu-P-filled ECA could be maintained consistently low after high temperature exposure at 125°C for 1000 h or aging at 85°C/85% RH for 1000 h, compared with the rapidly increased resistivity of Cu-filled ECA over time. A significantly low final resistivity at an order of magnitude of 10^?4 Ω·cm could be maintained in Cu-P-filled ECA even after aging at 85°C/85% RH for 1000 h.     

Contribution of Nitrated Polycyclic Aromatic Hydrocarbons in Diesel Particles to Human Lung Cancer Induction

By following the prognosis of 112 patients with carcinomas, we found that the deposition of 1-nitropyrene (1-NP), 1,3-dinitropyrene (1,3-DNP), and 3-nitrofluoranthene (3-NF) in lung tissues influenced their 5-year-survival after determination of chemicals. Lung specimens were divided into two groups of higher and lower chemical concentrations at levels of 18 pg/g for 1-NP, 15 for 1,3-DNP, and 35 for 3-NF, and the findings were statistically analyzed by adjusting for age, gender, stage, smoking status and cell type. The 5-year-survival of patients was significantly lower in the higher concentration group than the lower group. In addition, the higher concentration group correlated significantly with poor cell differentiation. The results suggest that tumors can be induced by continuous deposition of small amounts of environmental carcinogens in human lungs.

Formation of 8-hydroxyguanosine (8-OHdG) is normally used as a biomarker of oxidative damage in in vitro and in vivo systems. 8-OHdG was detected in all 22 cases of lung tissues with carcinomas, and levels increased with the increasing age of the patients, suggesting a correlation between age and the presence of diesel-originating carbon particles in lung tissues. In the inhatlacheal intratracheal administration diesel particles without most organic chemicals into mice, & OHdG formation was elevated more than by a single admummion of benzo[a]p,mne, 1-NP and 1,8-DNP. These results suggest that olbaneceous particles, but not mutagens or carcinogens, promote the formation of & OHdG, and that as a mechanism, alveolar mamphages may be assoCiated with oxidative damage, involving the generation of a hydroxyl radical during phagocytosis in the lungs.     

Immunological Effects of Oenothein B,an Ellagitannin Dimer,on Dendritic Cells

Oenothein B is a unique macrocyclic ellagitannin dimer that has been found in various medicinal plants belonging to Onagraceae, Lythraceae, and Myrtaceae, with diverse biological activities. The immunological effects of tannins in terms of cytokine-release from macrophages and monocytes have been discussed, while the effects on other immunocompetent cells have been the subject of minimal investigation. We evaluated the immunomodulatory effects induced by tannin treatment in human dendritic cells (DCs), which play a critical role in the initial immune response, by measuring the changes in cytokine production, cell differentiation, and cell viability. Oenothein B showed significant down-regulation of the expression of cell surface molecules, CD1a and CD83, suggesting the inhibition of DC differentiation and/or maturation. The suppressive effect on DCs was associated with the induction of apoptosis without the activation of caspase-3/7, 8, and 9, and this was supported by the morphological features indicating significant nuclear condensation. Oenothein B also markedly suppressed the production of inflammatory cytokines, such as IL-1β and IL-6, in a dose-dependent manner. These data may, in part, be able to explain the traditional use of tannin-containing medicinal plants for the treatment of a variety of inflammatory diseases, including inflammatory bowel disease, celiac disease, and rheumatoid arthritis.     

Serial Changes of Serum Growth Factor Levels and Liver Regeneration after Partial Hepatectomy in Healthy Humans

This study aimed to investigate the associations of the serial changes of serum levels of various growth factors with liver regeneration after hepatectomy in healthy liver donors. Sixteen healthy liver donors who underwent conventional liver resection were included. Serum levels of various growth factors before hepatectomy and on postoperative day (POD) 1, 3, 5 and 7 were measured. Liver volume data calculated by multi-detector computed tomography using workstation. The ratio of remnant liver volume on POD 0 to liver volume before the operation was 51% ± 20%. The ratio of liver volume on POD 14 to liver volume on POD 0 were inversely correlated with remnant liver volume on POD 0 (r = −0.91). The ratio of liver volume on POD 14 to liver volume on POD 0 were significantly correlated with serum hepatocyte growth factor (HGF) levels on POD 1 (r = 0.54), serum leptin levels on POD 1 (r = 0.54), and serum macrophage colony-stimulating factor (M-CSF) levels on POD 5 (r = 0.76) and POD 7 (r = 0.80). These results suggest that early-phase elevation of serum levels of HGF, leptin and M-CSF may be associated with the acceleration of liver regeneration after hepatectomy in humans.     

A windows software for simulation of the membrane excitation in nerve and skeletal muscle fiber.

A windows 95/98 software program for simulating membrane excitation in nerve and skeletal muscle fiber has been developed. This program simulates (1) the action potentials of the nerve under two conditions (space clamped conditions and conducting conditions), (2) the membrane currents of the nerve under voltage clamped conditions, and (3) the propagated action potentials of skeletal muscle fiber. Since users can utilize quadruple precision in the simulation of propagated action potentials, such simulation can be done for a long period (60 ms in skeletal muscle at 2 degrees C). In addition, users can change the conditions such as the capacitance of the membrane, the maximum conductance of the channel, etc., arbitrarily without quitting the program. It is also possible to easily modify the time and the voltage dependence of the gate particles in order to confirm the effects of various changes on the action potential or the membrane current. This program also has an analysis mode in which the current-voltage relationship of a channel can be measured automatically.