Nanostructure and mechanical properties of aromatic polyamide and reactive organoclay nanocomposites

Aromatic polyamide/organoclay nanocomposites were synthesized using the solution blending technique. Treatment of montmorillonite clay with p-phenylenediamine produced reactive organophilic clay for good compatibility with the matrix. Polyamide chains were prepared by condensing a mixture of 1,4-phenylenediamine and 4-4′-oxydianiline with isophthaloyl chloride under anhydrous conditions. These chains were end capped with carbonyl chloride using 1% extra acid chloride near the end of reaction to develop the interactions with organoclay. The dispersion and structure–property relationship were monitored using FTIR, XRD, FE-SEM, TEM, DSC and tensile testing of the thin films. The structural investigations confirmed the formation of delaminated and disordered intercalated morphology with nanoclay loadings. This morphology of the nanocomposites resulted in their enhanced mechanical properties. The tensile behavior and glass transition temperature significantly augmented with increasing organoclay content showing a greater interaction between the two disparate phases.     

Growth and characterization of Ni:DLC composite films using pulsed laser deposition technique

The structure and surface morphology of Ni-incorporated diamond like carbon (Ni:DLC) films have been investigated. These films were deposited on Si substrates using pulsed laser deposition (PLD) technique. A KrF Excimer laser (λ = 248 nm) was used for co-ablation from multi component Ni–graphite target. The concentration of Ni was varied by ablating the Ni part of the target with various numbers of laser pulses. The SEM and AFM analysis reveals that the surface is composed of segregates of Ni which increases with the increase in Ni content during the growth process. The structural investigations by XRD and Raman spectroscopy provided information about the orientation of the incorporated constituent and the ordering of the carbon species. Maximum height of the nano structures which were observed on the surface was ∼50 nm. The G-peak of the graphite was shifted towards higher wave number due to enhancement in SP² sites which have been increased due to the increase in the Ni concentration. A small change in the surface roughness ranging from 7.78 nm to 13.1 nm due to increased Ni concentration was also observed.     

Bile tolerance, taurocholate deconjugation, and binding of cholesterol by Lactobacillus gasseri strains

Bile tolerance, deconjugation of sodium taurocholate, and the cholesterol-binding ability of 28 strains of Lactobacillus gasseri were examined. There was significant variation among strains in growth in media containing bile and also variation in the ability to bind cholesterol. Cultures grown for 12 h at 37 degrees C bound significantly more cholesterol than did cells from a 48-h incubation. Variation among strains in the ability to deconjugate sodium taurocholate was not significantly different. Maximal deconjugation of sodium taurocholate was achieved with the cells during the stationary phase of growth (12 h). Statistical analysis showed no significant correlation between bile tolerance and sodium taurocholate deconjugation, bile tolerance and cholesterol-binding ability, or sodium taurocholate deconjugation and cholesterol-binding ability.     

Ranging Accuracy in Dynamic Spectrum Access Networks

Theoretical analysis of time-of-arrival (TOA)-based high-precision ranging algorithm for the dynamic spectrum access networks (DSANs) is performed. The asymptotic frequency-domain Cramer-Rao bound (CRB) of the ranging algorithm that takes the frequency-dependent feature (FDF) and phase of multipath components (MPCs) into account is derived through Whittle formula. The effects of FDF-MPCs and related parameters such as absolute bandwidth and operating center frequency on the ranging accuracy are investigated. The results show that the impacts of the FDF-MPCs on the ranging accuracy can be significant and it is recommended utilizing as large absolute bandwidth as possible at low operating center frequencies to obtain high-precision distance information of the users in the DSANs     

Inhibition of vascular smooth muscle cell proliferation by ribozymes that cleave c-myb mRNA

Proliferation of injured smooth muscle cells contributes to the reocclusion or restenosis of coronary arteries that often occurs following angioplasty procedures. We have identified and optimized nuclease-resistant ribozymes that efficiently cleave c-myb RNA. Three ribozymes targeting different sites in the c-myb mRNA were synthesized chemically and delivered to rat aortic smooth muscle cells with cationic lipids; all three inhibited serum-stimulated cell proliferation significantly. RNA molecules with two base substitutions in the catalytic core that render the ribozyme catalytically inactive had little effect on smooth muscle cell proliferation. Ribozymes with scrambled binding arm sequences also failed to affect cell cycle progression of vascular smooth muscle cells. Furthermore, inhibition of rat smooth muscle cell proliferation correlated with a reduction in intact c-myb mRNA. Efficacy of the chemically-modified ribozyme was compared directly to phosphorothioate antisense oligodeoxynucleotides targeting the same site in the c-myb RNA; the ribozyme had superior efficacy and showed greater specificity than the antisense molecules. Exogenously delivered ribozymes also inhibited porcine and human smooth muscle cell proliferation effectively. Ribozymes targeting c-myb or other regulators of smooth muscle cell proliferation may represent novel therapeutics for the treatment of restenosis after coronary angioplasty.     

Power Doppler findings in nasopharingeal angiofibroma

Three fractions of polysaccharides that have high biological activity were extracted from Chinese bamboo leaves (Indocalamus Tesselatus) with 0.9% sodium chloride, 1% ammonium oxalate and 85% ethanol. Their component sugars were investigated by paper chromatography developed with n-butanol-pyridine-water (6:4:3 by vol), and by gas chromatography with crown ester stationary-phase-fused silica capillary column. Their monosaccharide compositions are different from each other with glucuronic acid, galactose, arabinose, mannose, glucose, and xylose (52, 18, 9, 7 and 6%, respectively) in one fraction, only glucuronic acid in another and glucuronic acid, fucose, arabinose and xylose (36, 31, 24 and 9%, respectively) in the third fraction. The protection effect of two polysaccharides against experimental hepatitis was studied in mice.     

The effect of etomidate induction on plasma cortisol levels in children undergoing cardiac surgery

Loyalty to one's extended family, a well-known Japanese tradition, has broken down following World War II. Child rearing in Japan, therefore, has been changing gradually and clearly. Traditionally, child rearing was taught to young mothers by the grandmothers. However, recently young couples are no longer living with their parents. Therefore, there are no advisers nor consultants available at home for their child rearing. Commercialism has certainly invaded the field of child rearing, including too many guidebooks and even baby-sitting companies. Children's lives have become much more competitive, busy and unnatural in comparison with those of 20-30 years ago. This might be one cause of the increased incidence of bullying, school phobia and psychological disorders in children.     

Ozonation of synthetic versus natural textile tannins: recalcitrance and toxicity towards Phaeodactylum tricornutum.

A sound in-plant pollution control strategy can only be defined by paying due attention to bio-recalcitrance and toxicity. In this context the levels of toxicity and inert COD introduced to textile dyebath discharges by two alternative auxiliary chemicals, namely natural tannin (NT) and synthetic tannin (ST), were investigated. The effect of 40 minutes ozonation at 1,000 mg h(-1) at pH 3.5 on the segregated effluent streams containing the above-mentioned tannin formulations was evaluated in terms of changes in toxicity and recalcitrance. The effect of ozonation on the COD distribution of raw and ozonated NT and ST samples according to their molecular weight cut-offs was also assessed. Both untreated tannin formulations exerted high acute toxicity towards marine microalgae Phaeodactylum tricornutum. Moderate decrease in the toxicity levels of both tannins was observed upon ozonation. The raw NT formulation with a COD content more than twice that of its alternative raw ST had an initially inert soluble COD content of only 25 mg/L, while the initially inert COD was 135 mg/L for ST. As the initially inert soluble COD content of NT was considerably lower, this textile auxiliary did not need chemical pretreatment to improve its biodegradability. On the other hand, the initially inert soluble COD content of ST was reduced by 70% by ozone pretreatment. In terms of residual COD contents achievable after passing through a biological treatment system, raw NT and pretreated ST formulations yielded 100 and 95 mg/L COD, respectively. The highest proportion of COD (46% for NT and 88% for ST) was found in the <1 kDa range. The same fraction increased to 93% for NT after ozonation, while for ST no significant change was observed in the COD distribution of the molecular weight cut-offs after ozonation.     

Scheme for reducing size of coefficient memory in FFT processor

Long fast Fourier transforms (FFTs) are required in applications such as orthogonal frequency division multiplexing, radars and sonars. It is highly desirable to reduce the size and power requirements of the FFT so as to realise single chip long FFT-based systems targeting portable applications. Presented here is a novel technique to reduce the coefficient memory almost by a factor of four by exploiting the relationships among the coefficient values thereby significantly reducing the area and power requirements of the hardware     

Castleman's disease. A case report

Angiofollicular lymph node hyperplasia or Castleman's Disease (CD) is a rare lymphoproliferative disorder that manifests itself as a local or generalized tumor-like condition affecting both lymph nodes and non-nodal tissues, usually in the chest and abdomen. Hyaline vascular and plasma cell types have been identified histologically. A new clinical form of CD with multisystemic involvement has been defined as multicentric Castleman's disease. It is very rare in childhood. In this paper we present an eight-year-old boy with multicentric Castleman's disease.