Reduced frequency effects on the near-wake of an oscillating elliptic airfoil

An experimental study was carried out to investigate the reduced frequency effect on the near-wake of an elliptic airfoil oscillating in pitch. The airfoil was sinusoidally pitched around the center of the chord between -5° and +25° angles of attack at an airspeed of 3.4 m/s. The chord Reynolds number and reduced frequencies were 3.3 X104, and 0.1, 0.7, respectively. Phase-averaged axial velocity and turbulent intensity profiles are presented to show the reduced frequency effects on the near-wake behind the airfoil oscillating in pitch. Axial velocity defects in the near-wake region have a tendency to increase in response to a reduced frequency during pitch up motion, whereas it tends to decrease during pitch down motion at a positive angle of attack. Turbulent intensity at positive angles of attack during the pitch up motion decreased in response to a reduced frequency, whereas turbulent intensity during the pitch down motion varies considerably with downstream stations. Although the true instantaneous angle of attack compensated for a phase-lag is large, the wake thickness of an oscillating airfoil is not always large because of laminar or turbulent separation.     

NORM workers: a challenge for internal dosimetry programmes

The mining, milling and processing of uranium and thorium bearing minerals may result in radiation doses to workers. The control of occupational exposures from these natural sources of radiation imposes a challenge to regulators and radiation protection advisers. A survey pilot programme, which included six mines in Brazil and a monazite plant, was established, consisting of the collection and analysis of concentrations of uranium, thorium and polonium in urine, faeces and air samples. Results from workers were compared to background data from their families living in the same area and from residents from the population of Rio de Janeiro. Positive exposure results were identified among the coal miners, the niobium miners and the monazite sand workers. Difficulties in the application of internal dosimetry programmes are discussed in relation to the control of NORM workers.     

Observations of infrared bands of asymmetrical ozone isotopologues 16O16O18O and 16O18O18O

Infrared spectra (0.003 cm(-1) resolution) of 16O16O18O and 16O18O18O ozone isotopologues have been recorded and analyzed in the range 600-5000 cm(-1). Several thousand rovibrational lines belonging to 32 absorption bands have been measured and assigned. An accurate determination of band centers through the rovibrational analysis has been done, 12 bands being observed for the first time to our knowledge. In addition to atmospheric retrieval applications, these results are also useful for a validation of potential energy surfaces and for the study of isotope effects in dynamic processes of ozone.     

Fabrication of CdO–Bi2O3 Ceramics

The phase formation in the CdO-rich part (10 wt % Bi₂O₃) of the CdO–Bi₂O₃ system was studied by x-ray diffraction, IR spectroscopy, electron microscopy, and other techniques. The results indicate that the grinding of the starting powder mixtures in a planetary mill leads to an inhomogeneous Bi₂O₃ distribution and a high defect density in the CdO and Bi₂O₃ particles. Sintering in the range 910–990 K gives rise to the formation of the _h phase, whose content depends strongly on the mixture composition and sintering conditions. At sintering temperatures above its melting point, the _h phase acts as a binder of CdO grains.     

Peptide rearrangement during quadrupole ion trap fragmentation: added complexity to MS/MS spectra

The emergence of proteomics has placed great interest in the understanding of the mechanisms of MS/MS fragmentation of peptides under low-energy collision-induced dissociation. In this work, we describe the presence of anomalous fragments, which correspond to neutral loss elimination of internal amino acids from ions of the b series in quadrupole ion trap MS/MS spectra from naturally occurring peptides. Internal amino acid elimination occurred preferentially with aliphatic amino acids. The phenomenon was more apparent when doubly charged precursors were fragmented and was inhibited when peptides were N-acetylated at the N-terminus. Fragmentation of isomeric peptides where some internal amino acids were relocated in N-terminal position produced MSn spectra indistinguishable from those of the original peptides, indicating that some b ions underwent a structural rearrangement process. Formation of anomalous fragments required a minimum activation time. Our data are consistent with a nucleophile attack of the N-terminal nitrogen over the electrophilic carbonyl carbon at one peptide bond, forming a cyclic b ion intermediate that, by reopening at preferential sites, exposes internal amino acids to the C-terminal side.     

Permeation of naproxen from saturated solutions and commercial formulations through synthetic membranes

The release of naproxen through synthetic membranes, mounted in modified Franz-type diffusion cells, was evaluated, either from saturated solutions or from commercially available topical formulations containing 10% naproxen. The results obtained showed that the porous type synthetic membranes chosen (cellulose acetate and polyethersulphone) can be used for assessing product performance in quality control procedures. The formulations interacted with the solid membranes (silicone and EVA) to change their diffusional characteristics. However, transfer in the membrane, and not the formulation was rate controlling. These membranes could not therefore be used in assessing product release performance for quality control.     

Harmonic ultrasonic field of medical phased arrays: simulations and measurements

With the introduction of harmonic imaging, the design of new array transducers for tissue and contrast imaging became indispensable. Hence, prior knowledge of harmonic beams is essential to attain optimal harmonic performances. For that purpose, a new numerical algorithm that solves the parabolic nonlinear wave equation is developed. The algorithm is based on finite differences and performs exclusively in time domain. Pulsed harmonic fields emitted by a medical transducer were measured and computed at different mechanical indices. Simulations and measurements showed very good agreement for all the harmonic components.     

Effect of crosslinking, thermal treatment and UV irradiation on the mechanical properties and in vitro degradation behavior of several natural proteins aimed to be used in the biomedical field

Gelatine (GEL), soy (SI), casein (CAS) and sodium-caseinate (NaCAS) solutions were cast to produce protein films. All the proteins were chemically modified by adding glyoxal to the film-forming solutions in amounts varying from 0 to 0.9% (w/w based on the protein content). After casting, the same films were also submitted to a heat treatment performed at 80 °C or UV irradiation. The effect of those chemical/physical modifications on the mechanical properties and on the hydrolytic stability of the protein films was evaluated. As a result, a large variety of protein films with different mechanical properties and degradation profiles were developed. CAS and NaCAS even when chemically/physically modified do not resist to hydrolysis longer than 2 weeks. GEL, only when chemically modified with glyoxal, become water resistant. Due to its hydrolytic stability, SI become a very attractive material for biomedical applications where long term treatments are a requisite.     

In vitro degradation and cytocompatibility evaluation of novel soy and sodium caseinate-based membrane biomaterials

Soy- and casein-based membranes are newly proposed materials disclosing a combination of properties that might allow for their use in a range of biomedical applications. Two of the most promising applications are drug delivery carrier systems and wound dressing membranes. As for all newly proposed biomaterials, a cytotoxic scanning must be performed as a preliminary step in the process of the determination of the compatibility with biological systems (biocompatibility). In this study, the cytotoxicity of both soy- and casein-based protein biomaterials has been evaluated and correlated with the materials degradation behavior. It was possible to show, through morphological and biochemical tests that these natural origin materials do not exert any cytotoxic effect over cells, and in some cases can in fact enhance cell proliferation. The different treatments to which the membranes were subjected during their processing (that include crosslinking with glyoxal and tannic acid, and physical modification by thermal treatment) seemed to have a clear effect both on the materials mechanical properties and on their in vitro biological behavior.     

Nanohybrid scratch resistant coatings for teeth and bone viscoelasticity manifested in tribology

We cover teeth surfaces with nanohybrid coatings containing an inorganic ceramic and an organic copolymer constituents. We report the first ever values of scratch penetration depth and scratch recovery for bare and coated teeth. We find that uncoated teeth undergo viscoelastic recovery (healing) after microscratching – the first manifestation of bone viscoelasticity in tribology. The coatings fill "valleys" in teeth surfaces. In each case a large improvement in the scratch resistance as compared to uncoated teeth is seen. The extent of the improvement depends on the inorganic/organic component ratios in the nanohybrids. Electronic Publication