Adhesion of CVD diamond films on silicon substrates of different crystallographic orientations

In order to gain insight into the adhesion mechanisms of diamond films, we examine Si substrates with three different crystallographic orientations at the various stages of the deposition process. This allows one to distinguish the surface phenomena involved in diamond deposition from those due to gaseous plasma processes. We find that the initial ultrasonic scratching treatment produces partial graphitization of the diamond powder, and it controls the crystallite size through the carbon residues. On the other hand, an increased surface roughness due to H-atom etching correlates with increased adhesion. The deposited film adhesion is found to increase in the sequence Si(111)相似文献   

Analog circuit simulation of magnetic dipole behavior according tothe Langevin-Weiss theory of ferromagnetism

An analog electronic circuit designed to illustrate the principles of ferromagnetism by simulating the behavior of elementary magnetic dipoles as described by the Langevin-Weiss theory is presented. The device is intended to help undergraduate students master the fundamental ideas that explain the properties of ferromagnetic materials. The circuit design is described and related to the concepts used in the Langevin-Weiss theory, which is briefly outlined. Results obtained with the simulator are presented as oscilloscope traces and illustrate some of its possible uses     

Membrane formation with presence of Lewis acid–base complexes in polymer solution

This work investigated membrane formation using Lewis acid–base complexes in a polymer solution, which consisted of poly(ether sulfone) (PES), Lewis acid–base complexes formed by N‐methyl‐2‐pyrrolidone (NMP, Lewis base), and dicarboxylic or monocarboxylic acids from a homologous series (Lewis acids). The solutions were characterized by viscosity measurements, IR spectroscopy, cloud point determination, and light transmission experiments. The membranes were characterized by scanning electron microscopy and gas permeation tests. The results indicated that the solvent–additive interaction, which is a function of their capacity to form complexes, and the acid chain length directly affect the viscosity and miscibility region. Consequently, these parameters combined with the complex dissociation influence the precipitation velocity of the polymer solutions, which will then affect the membrane transport properties. It is also pointed out that the membranes prepared by using 25 wt % PES at the same acid/NMP molar ratios and with different acids presented permeability coefficients in agreement with the binodal shift obtained in pseudoternary phase diagrams. Furthermore, when these solutions were exposed to the environment for a long period of time, the demixing onset sequence also agreed with the miscibility region for all solutions, except for the adipic acid solution because of its extremely high viscosity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2022–2034, 2002     

Spectrum of liver diseases in HIV infection

BACKGROUND: Most earlier reports on the spectrum of liver diseases in HIV-infected individuals originated from the West. OBJECTIVE: To study the spectrum of liver diseases in HIV-infected individuals. METHODS: Seventy four consecutive HIV-positive patients (57 men; age range 23-75 years, mean 34) were studied prospectively with clinical evaluation, liver function tests, ultrasonography, radioisotope liver scan, markers of hepatitis B (HBV) and C (HCV) viruses, and liver histology whenever necessary. RESULTS: Thirty four patients (45%) were chronic alcoholics. Mean (SD) absolute lymphocyte count was 2521 (1271)/mm3; count < 2000/ mm3 was present in 20 patients. Serum bilirubin, transaminases and alkaline phosphatase levels were elevated in 13%, 13% and 24% of patients, respectively. Ultrasonography detected an abscess in two patients (tuberculous-1, amebic-1). Evidence of exposure to HBV was present in 81% (HBsAg-12, hepatitis B core and/or surface antibody-48); anti-HCV antibody was positive in 29.7%. Five patients with liver tuberculosis (granuloma-4, abscess-1) had AFB either in liver tissue or lymph nodes. CONCLUSION: Chronic alcoholism, HBV and HCV infection, hepatic tuberculosis, and evidence of other liver disease were common in patients with HIV infection.     

Compositional differences of coriander fruit oils from various origins

The composition of the volatile oil of coriander fruit of different geographical origins was investigated by means of gas-liquid chromatography, column chromatography and coupled gas chromatography-mass spectrometry. The 18 most important components were identified and quantified.     

Application of a first order perturbation method to the analysis of almost periodic multiport network chains

Contents Propagation parameters of cascaded multiconductor transmission structures can be easily determined when the chain is strictly periodic. If periodicity is somehow perturbed, which is usually the real case, the evaluation of the chain propagation parameters becomes very complex, especially when the number of cascaded sections is large. To handle this situation we propose an approach based on a standard first order perturbation method allowing a simple relationship to be found between the chain parameters and those characterizing its component cells. The method is first developed for general 2n-port networks and later particularized for the special case of two-port transmission-line systems. Graphs with numerical results are presented allowing the accuracy of the method to be checked.

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Anwendung einer störungsmethode erster Ordnung für die Untersuchung fastperiodischer Ketten aus Mehrtornetzwerken

Übersicht Die Berechnung der Wellenparameter von Ketten aus Mehrleiter-Übertragungsystemen bietet keine Schwierigkeit im Fall streng periodischer Ketten. Wird die Periodizität gestört, wie es in der Praxis häufig vorkommt, so wird die Berechnung sehr mühsam, besonders dann, wenn die Kette viele Glieder enthält. Um diese Schwierigkeit zu überwinden, schlagen wir die Anwendung einer gewöhnlichen Störungsmethode erster Ordnung vor, die es gestattet, eine einfache Beziehung zwischen den Wellenparametern der Kette und den Wellenparametern der einzelnen Glieder zu gewinnen.Die Methode wird zuerst für allgemeine 2n-Tore entwickelt und danach auf den Sonderfall der Zweitor-übertragungssysteme angewandt.Die Genauigkeit des Verfahrens läßt sich aus der graphischen Darstellungen numerischer Ergebnisse ablesen.

     

Direct liquefaction of hydrolytic eucalyptus lignin in the presence of sulphided iron catalysts

The liquefaction of hydrolytic eucalyptus lignin has been studied in hydrogen donor and non-donor solvents in the presence of ferrocene and of ferrocene associated with sulphur or carbon disulphide. With the exception of tetralin, all reactions were carried out at supercritical conditions of the solvent. It was found that the yields of heavy oils increase significantly with the increase in hydrogen pressure in the non-donor solvents. The oil yields also increase with the density of the solvent but level out at densities higher than 0.30 g/ml. The consumption of molecular hydrogen is significant in the non-donor solvents; in the donor solvents the hydrogen is mostly transferred from the solvent itself. In the non-donor solvents, the oil yields depend strongly on the efficiency of the catalyst, but not in the donor solvents.     

Exploiting Unique Alignment of Cobalt Ferrite Nanoparticles,Mild Hyperthermia,and Controlled Intrinsic Cobalt Toxicity for Cancer Therapy

Nanoparticle-based magnetic hyperthermia is a well-known thermal therapy platform studied to treat solid tumors, but its use for monotherapy is limited due to incomplete tumor eradication at hyperthermia temperature (45 °C). It is often combined with chemotherapy for obtaining a more effective therapeutic outcome. Cubic-shaped cobalt ferrite nanoparticles (Co–Fe NCs) serve as magnetic hyperthermia agents and as a cytotoxic agent due to the known cobalt ion toxicity, allowing the achievement of both heat and cytotoxic effects from a single platform. In addition to this advantage, Co–Fe NCs have the unique ability to form growing chains under an alternating magnetic field (AMF). This unique chain formation, along with the mild hyperthermia and intrinsic cobalt toxicity, leads to complete tumor regression and improved overall survival in an in vivo murine xenograft model, all under clinically approved AMF conditions. Numerical calculations identify magnetic anisotropy as the main Co–Fe NCs’ feature to generate such chain formations. This novel combination therapy can improve the effects of magnetic hyperthermia, inaugurating investigation of mechanical behaviors of nanoparticles under AMF, as a new avenue for cancer therapy.     

Toughening of Epoxy Resin by Methyl Methacrylate/2‐Ethylhexyl Acrylate Copolymers: The Effect of Copolymer Composition

MMA‐EHA copolymers with different compositions and with a low amount of AA were synthesized and used as impact modifier for epoxy networks. The effect of the copolymers on the tensile and dynamic mechanical properties as well as impact resistance of the epoxy network was evaluated. The addition of 10 phr of low‐molar‐mass MMA‐EHA copolymer with defined composition resulted in a significant increase in impact resistance without any significant changes in the tensile strength, modulus, and glass transition temperature. The morphology of the modified epoxy network depends upon the copolymer composition.

     

Seasonal variation of physical,chemical and sensory characteristics of sea bream (Sparus aurata) reared under intensive conditions in Southern Europe

This study describes the variability of important quality traits in gilthead sea bream produced under intensive conditions in Southern Europe and purchased in a French market (Nantes). Chemical, sensory and histological characteristics were performed on 18 samples delivered over a year. All fish presented far lower dioxin and DL-PCBs or heavy metals concentrations than the maximum limit level set by EC Regulation, being totally safe for human consumption. Fat content and nutritional values reflected by n-3 and n-6 polyunsaturated fatty acids (PUFA) levels were parameters with high variability according to the season or the fish farm. Values of n-3 PUFA ranged from 0.9% to 8.6% and those of n-6 PUFA from 9.3% to 16.6%, corresponding to a respective variation of n-3/n-6 ratio between 0.1 and 0.6. Increased fat levels in flesh lead to a more intense odour, a fatty fish flavour and a whiter appearance of the cooked fillet. Flesh total amino acid composition was rather stable whereas the small differences detected on firmness by the sensory panel were weakly related to histological characteristics. Rearing techniques of the farm seems to modulate the major characteristics of the fish.