Sub-millimeter-long carbon nanotubes repeatedly grown on and separated from ceramic beads in a single fluidized bed reactor

A semi-continuous fluidized-bed process is reported which rapidly converts acetylene into carbon nanotubes (CNTs). Catalysts are first immobilized on ceramic beads and CNTs are then grown on the beads and then separated from them in a repetitive process accomplished within a single reactor simply by switching gases at a fixed temperature. CNTs of 6–10 nm diameter, three walls on average, 0.4 mm length and 99 wt.% purity were synthesized at an yield of over 70% in a reactor residence time shorter than 0.3 s. The easy and efficient production of such CNTs with in situ separation from the catalysts may accelerate the development of CNT-based nanotechnology industries.     

Triple‐junction effect and its electric field relaxation in three dielectrics

This paper analyzes the electric field distribution near a wedge‐like edge in arrangements consisting of three dielectrics using analytical and numerical methods. The electric potential behaves exponentially as rⁿ (r is the distance from the edge) near the edge, leading to an infinitely high field with decreasing r for all cases. The value of the analytically derived exponent n agreed well with that obtained from the numerical field calculations. It has also been demonstrated that rounded contact of the spacer with a zero contact angle can make the electric field constant without showing an exponential rise near the edge. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 167(1): 1– 8, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20670     

Development of bioactive materials based on surface chemistry

All bioactive materials developed up to 1990 were based on calcium phosphate. It was later revealed that materials that form bonelike apatite on their surfaces in the living body bond to living bone through the apatite layer, and that apatite formation on a material is induced by various functional groups on its surface. Based on these findings, bioactive titanium was prepared by forming sodium titanates on its surface via NaOH and heat treatments, and applied to an artificial total hip joint. Porous titanium metal able to exhibit osteoconductivity as well as osteoinductivity was prepared by forming anatase on its surface via NaOH, HCl and heat treatments. Various bioactive materials with different physical properties are expected to be derived from ceramics, metals and organic polymers by modifying their surfaces with functional groups effective for apatite nucleation.     

Bioactive bone cement: comparison of AW-GC filler with hydroxyapatite and beta-TCP fillers on mechanical and biological properties

The density of lipophorin was determined in adult females of Rhodnius prolixus on different days after a meal. Several populations od lipoproteins, differing in density but always in the range of HDL, were found in the hemolymph. The density of the major population was analyzed and a complex profile of density variation was found associated with the principal metabolic events in these insects digestion and oogenesis. During the initial three days after the blood meal, with the onset of the digestive process, the density of lipophorin decreased from 1.1185 g/l to 1.1095 g/l, associated with the transfer of lipids from midgut to the lipophorin particles. During the period of intense vitellogenesis and lipid uptake by the ovary, the lipophorin density started to increase and reached the value, 1.1322 g/l, and remained stable up to the end of oogenesis. As soon as the requirement of lipids to build up the oocytes ceased, the density of lipophorin decreased to its initial value associated with the transfer of lipids from fat body to lipophorin. Soon after the blood meal the midgut was the main source of lipids capable of replenishing the lipophorin particles, while the fat body assumed this function during the succeeding days and reached its maximum capacity around day 10, as estimated by the rate of lipid transfer. The principal lipids transferred were phospholipids and diacylglycerols. Except in the protein/lipid ratio no major changes were observed among different lipids isolated from lipophorin of different densities.     

Pervaporation separation of water/ethanol mixtures through polysaccharide membranes. II. The permselectivity of chitosan membrane

The separation of water/alcohol mixtures through chitosan membrane was investigated. The degree of the deacetylation of chitosan did not affect the selectivity of the membrane in the separation of the water/ethanol mixture. The selectivity of the chitosan membrane was affected by the specific salts such as CoSO₄, ZnSO₄, and MnSO₄ and it increased when the salts were present in the feed mixture or the membrane was pretreated with the salt solution. This behavior would be explained by the contraction of the “holes” produced by the thermal motion of polymer chains and this contraction would be correlated with the conformation change of chitosan molecule due to the formation of complexes with metal ions.     

Preparation of fine polymer particles containing metallocene derivatives

This article deals with preparations of fine particles of metallocene copolymers by emulsifierfree emulsion polymerization of vinylferrocene (VFc), ferrocenylmethyl methacrylate (FMMA), 1-ferrocenylethyl methacrylate (1-FEMA), 2-ferrocenylethyl methacrylate (2-FEMA), and 1-ruthenocenylethyl methacrylate (1-REMA) with acrylonitrile (AN), styrene (St), and methyl methacrylate (MMA) in water/ethanol medium. As a result, spherical copolymer particles containing metallocene derivatives have been successfully synthesized in the particle size of ca. 120 to 600 nm. The contents of ferrocenyl or ruthenocenyl groups in copolymer particles increased with increasing concentration of charged metallocene derivatives, while the amounts of metallocene derivatives incorporated into particles are much lower than the charged ratio. © 1994 John Wiley & Sons, Inc.     

Enhanced antiviral activity of soybean β-conglycinin-derived peptides by acylation with saturated fatty acids

Abstract: Peptide mixtures prepared from soybean β‐conglycinin (7S‐peptides) were acylated with saturated fatty acids of different chain length (6C‐18C) in order to improve their antiviral activity against Feline calicivirus (FCV) strain F9 which is a typical norovirus surrogate. Among the fatty acids varieties, it was revealed that 7S‐peptides acylated with myristic and palmitic acids potently inhibited FCV replication. Myristorylation and palmitoylation of 7S‐peptides kept host cells viability at 91.51% and 98.90%, respectively. The infectivity of FCV on Crandell–Reese feline kidney cells was further determined after exposure of initial titer of 10^6.47 TCID₅₀/mL. Myristoylated and palmitoylated 7S‐peptides significantly (P < 0.006) reduced FCV infectivity as compared to native 7S‐peptides. Native 7S‐peptides showed 25% FCV inhibitory activity while myristoylated and palmitoylated 7S‐peptides exhibited 98.59% and 99.98% reduction in FCV infectivity, respectively. Myristoylated and palmitoylated 7S‐peptides demonstrated higher anti‐FCV activity in a wide range of concentration with complete reduction at 25 μg/mL. Surface hydrophobicity was significantly (P < 0.05) increased after attachment of long hydrocarbon fatty acids to 7S‐peptides as supported by changes in fluorescence intensity. Enzymatic hydrolysis together with acylation will give an insight into surface and physiological functional lipopeptides derived from soy β‐conglycinin.     

Nanostructured positively charged bioactive TiO<Subscript>2</Subscript> layer formed on Ti metal by NaOH,acid and heat treatments

Nanometer-scale roughness was generated on the surface of titanium (Ti) metal by NaOH treatment and remained after subsequent acid treatment with HCl, HNO₃ or H₂SO₄ solution, as long as the acid concentration was not high. It also remained after heat treatment. Sodium hydrogen titanate produced by NaOH treatment was transformed into hydrogen titanate after subsequent acid treatment as long as the acid concentration was not high. The hydrogen titanate was then transformed into titanium oxide (TiO₂) of anatase and rutile by heat treatment. Treated Ti metals exhibited high apatite-forming abilities in a simulated body fluid especially when the acid concentration was greater than 10 mM, irrespective of the type of acid solutions used. This high apatite-forming ability was maintained in humid environments for long periods. The high apatite-forming ability was attributed to the positive surface charge that formed on the TiO₂ layer and not to the surface roughness or a specific crystalline phase. This positively charged TiO₂ induced apatite formation by first selectively adsorbing negatively charged phosphate ions followed by positively charged calcium ions. Apatite formation is expected on the surfaces of such treated Ti metals after short periods, even in living systems. The bonding of metal to living bone is also expected to take place through this apatite layer.     

Bubble behavior in vertical tube banks installed in a fluidized bed

Fluidized bed combustion is one of the advantageous technologies for coal and/or incineration firing especially with respect to the environmental protection of emissions, such as NO_x/SO_x. Bed material movement in such a fluidized bed has a prime importance in the heat transfer process. Thus, quantitative measurement of the bed material movement and the void fraction are indispensable for better understanding of the fluidized bed. In this investigation, neutron radiography is applied to visualize the bed material movement in a simulated fluidized bed heat exchanger installed with vertical tubes. Bubble behavior and void fraction profile are obtained by the image processing technique. Bubble movement is highly restrained by these vertical tubes, so that the bubbles rise up along the tube. The bubble diameter is well correlated by the modified Mori and Wen's correlation taking into account the pitch of the tube arrangement. The bubble rise velocity and void fraction are well correlated by applying the drift‐flux model. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(8): 727–739, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.10127