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In the present study, the photocatalytic activity of TiO

The mechanisms and kinetics of the sonochemical degradation of organic molecules in water are relatively complex since several parameters such as physicochemical properties, substrate concentration, water matrix, reactor geometry, ultrasound properties (frequency, power, emission system) all typically affect the process. In this work, simple kinetic models were used to predict the degradation of 2-chlorophenol and sodium dodecylbenzene sulphonate in aqueous solutions and verified against experimental data taken from previous studies. A pseudo-first order kinetic expression can adequately describe the degradation of the phenolic substrate, while a heterogeneous model based on the Langmuir-Hinshelwood equation is suitable for the surfactant degradation.

Introduction The purpose of this study is to present the five-year survival and function of the renal allograft of recipients who were diagnosed with BK viremia and viruria during the first year after renal transplantation. Patients and Methods BK virus was studied in 32 new renal allograft recipients, from the first postoperative day until 18 months after the transplantation. Real-time polymerase chain reaction was used to detect and quantitate BK viral load in serum and urine samples. Results Qualitative analysis with PCR for the DNA of BK virus showed 31 (31/228, 14%) positive serum samples originating from 20 (20/32, 62%) renal allograft recipients and 57 (57/228, 25%) positive urine samples originating from 23 (23/32, 72%) recipients. During the follow up period of 5 years, renal allograft function remained stable (eGFR 18 th month: 53.9 ± 23.9 mL/min/1.73 m 2 and eGFR 5 th year: 52.6 ± 20.6 mL/min/1.73 m 2 ). Comparison of recipients that presented with either BK viremia or viruria with a group that did not present viral reactivation did not reveal a statistically significant difference in eGFR. Furthermore, recipients with significantly high viral load in serum or urine did not present renal allograft dysfunction. Conclusion BK virus is potentially pathogenic in renal allograft recipients. It is certain that there is a reactivation of the virus in a high percentage of transplanted patients mostly in the first year after the surgery, without however a negative effect of the transient viremia and viruria in renal allograft function.

Reaction calorimetry measurements have been performed and used for the calculation of the heat of reaction, the thermal mass of the reactor and for the development of a global kinetic model for the homogeneous catalytic decomposition of hydrogen peroxide, which is a commonly encountered unwanted reaction in numerous oxidation processes. The use of this model targets the assessment of the thermal risk associated with the runaway behaviour of this reaction at industrial conditions.

This work presents the challenges and directions in biomaterials research. Biomaterials have been playing an important role in the treatment of disease and the improvement of healthcare. Metals were used in dentistry while synthetic polymers have been used for vascular grafts; polymethylmethacrylate and stainless steel have been used in total hip replacements. Controlled drug delivery systems largely involve biomedical polymers and are used by tens of million of people annually. Furthermore, in tissue engineering, by combining polymers with mammalian cells, it is now possible to engineer skin for patients who have burns or skin ulcers. Until recently, biomaterials were adopted from other areas of science and technology with little design for biomedical use, which did not help to completely resolve issues in biocompatibility, mechanical properties, degradation, etc. Modern biomaterial science is laying the foundation for a fundamental design by taking into consideration cell-matrix interactions, cellular signaling processes, and developmental biology. Concepts that are shaping future directions are biomaterials for specific biomedical applications made from naturally occurring or man-made building blocks or novel applications for biomaterials, such as diagnostics and array technologies.

Promising approaches to regenerate corneas, heart valves, and thymus have been presented in recent press releases. These are described here: Tsai et al. in The New England Journal of Medicine presented a promising technology to reconstruct damaged ocular surfaces; CryoLife wants to conduct clinical trials for the use of its Synergaft tissue-engineered replacement heart valves in heart reconstruction surgery for children requiring replacement of the pulmonary heart valve; NIST Researchers at Cytomatrix and Massachusetts General Hospital have generated an "artificial thymus" that can efficiently generate large quantities of a wide range of human T-lymphocyte cells, a key element of the body's immune system.

To develop a general model to describe the N-oxidation of the family of pyridines, the homogeneous catalytic N-oxidation of 2-methylpyridine has been studied. The reaction was performed in a semibatch reactor, dosing with hydrogen peroxide. The N-oxidation is accompanied by the competitive decomposition of hydrogen peroxide. The system was modeled taking into consideration the fast reversible reactions that result in intermediates, which react further to form the final products. Calorimetric information was used for the calculation of the concentration of reactants. These were subsequently used for the calculation of the reaction rates. It was found that each reaction proceeds through more than one path. The model parameters were evaluated. In spite of the complexity of the reaction system and the generalised expressions used the model can reproduce experimental data efficiently.

Chronic ulcerative dermatopathy (CUD) also known as chronic erosive dermatopathy, hole-in-the-head, head and lateral line erosion syndrome (HLLE) and lateral line depigmentation (LLD) is a chronic disease of unknown aetiology that affects the lateral line canals of the head and the trunk of various fish species. It has been described only in freshwater species although there are reports that it also affects marine fish. Here, we describe the disease in cultured sharpsnout sea bream using histology and scanning electron microscopy and identify several marine species as CUD sensitive. The results of this study correlate the development of the disease with the use of borehole water, indicating that the aetiology is probably associated with water quality rather than nutritional imbalance or infectious agents.

Over the past 20 yr, great strides have been made toward understanding the role of fluid hemodynamic forces in the vascular wall homeostasis at the molecular level. In vivo studies have demonstrated that blood vessels are adaptive to physiological changes in blood flow, with vessels tending to enlarge in areas of high flow and tending to reduce their lumen diameter in low-flow regimes (1,2). Furthermore, altered hemodynamics have been implicated in the pathogenesis of many cardiovascular disorders, such as thrombosis, atherosclerosis, and vessel wall injury. Vascular endothelial cells serve as a barrier between perfused tissues and flowing blood, and they are believed to act as a sensor of the local biomechanical environment. The hemodynamic forces generated in the vasculature include frictional wall shear-stress, cyclic strain, and hydrostatic pressure (3). For the purpose of this chapter, we will focus on methods for examining the link between fluid wall shear-stress and endothelial cell function. Advances in our understanding of the effects of shear-stress on endothelial cell function require that cell populations be exposed to controlled, well-defined, flow-induced shear-stress environments. Since in vivo studies have the inherent problem that they cannot quantitatively define the shearing forces or separate their effects from the other components of the hemodynamic system, in vitro flow studies using cultured cells are extensively used.

New, absolute values of the thermal conductivity of two refrigerants, R134a and R141b, in the liquid phase at saturation are reported. The measurements have been performed in transient hot-wire instruments making use of electrically insulated tantalum wires within the temperature range 240–307 K. The results are estimated to have an accuracy of ±1%.

New absolute measurements of the viscosity of n-decane and binary mixtures of n-heptane with n-decane are presented. The measurements, performed in a vibrating-wire instrument, cover a temperature range 290–330 K and pressures up to 70 MPa. The concentrations studied are 40 and 70% by weight of n-heptane. The overall uncertainty in the reported viscosity data is estimated to be ±0.5%. The present measurements together with other n-heptane+n-alkane viscosity and thermal conductivity measurements, are used to develop a consistent semiempirical scheme for the correlation and prediction of these mixture properties from those of the pure components.

A previously-described method is used for the simultaneous correlation of the coefficients of selfdiffusion, viscosity and thermal conductivity for acetonitrile, carbon disulphide, tetrachloromethane, cyclohexane, ethene and trichloromethane at densities above the critical density. The method, which has been developed from consideration of exact hard-sphere theory of transport properties, introduces just two molecular parameters; a characteristic volume v 0 and a roughness factor R, which take into account departure from spherical shape and molecular roughness. Values are given for these parameters. For a given compound, V 0 is temperature dependent but has the same value, at a given temperature, for the different properties. The R factor has a different value for each property, but these are independent of temperature and density.

Viscosity and thermal conductivity coefficients for binary, ternary, and quaternary n-alkane mixtures are predicted over extended ranges of temperature and pressure, in excellent agreement with experiment, by extension of a method recently described for the correlation of n-alkane transport coefficients. The outstanding advantage of this approach is that there are no adjustable parameters. Furthermore, in contrast with other mixture viscosity equations, this scheme does not require experimental viscosity coefficient data for the pure components under the same conditions of temperature and pressure.

New absolute measurements of the viscosity of binary mixtures of n-heptane with n-hexane and n-nonane are presented. The measurements, performed in a vibrating-wire instrument, cover a temperature range 290–335 K and pressures up to 75 MPa. The concentrations studied are 40 and 70% by weight of n-heptane. The accuracy of the reported viscosity data is estimated to be ±0.5%. The present measurements, together with other n-heptane + n-alkane viscosity and thermal-conductivity measurements, are used to develop a consistent semiempirical scheme for the correlation and prediction of these mixture properties from those of the pure components.

A previously described method, based on considerations of hard-sphere theory, is used for the simultaneous correlation of the coefficients of viscosity, self-diffusion, and thermal conductivity for then-alcohols, from methanol ton-decanol, in excellent agreement with experiment, over extended temperature and pressure ranges. Generalized correlations are given for the roughness factors and the characteristic volume. The overall average absolute deviations of the experimental viscosity, self-diffusion, and thermal conductivity measurements from those calculated by the correlation are 2.4, 2.6, and 2.0%, respectively. Since the proposed scheme is based on accurate density values, a Tait-type equation was also employed to correlate successfully the density of then-alcohols. The overall average absolute deviation of the experimental density measurements from those calculated by the correlation is ±0.05%.

New absolute measurements, by the transient hot-wire technique, of the thermal conductivity of some alkyl ethers and alkanones are presented. The alkyl ethers studied are tert-butyl methyl ether, di-iso-propyl ether and di-butyl ether, while the alkanones studied are 2-butanone, 4-methyl pentan-2-one, and 2-octanone. The temperature range examined was 295–350 K, and the pressure atmospheric. The overall uncertainty in the reported thermal conductivity data is estimated to be better than ±1%, an estimate confirmed by the measurement of the thermal conductivity of water.

New absolute measurements of the viscosity of n-heptane, n-nonane, and n-undecane are presented. The measurements were performed with a vibrating-wire instrument at temperatures of 303.15 and 323.15 K and pressures up to 70 MPa. The overall uncertainty in the reported viscosity data is estimated to be ±0.5%. A recently developed semiempirical scheme for the correlation and prediction of the thermal conductivity, viscosity, and self-diffusion coefficients of n-alkanes is applied to the prediction of the viscosity of n-heptane, n-nonane, and n-undecane. The comparison of these predicted values with the present high-pressure measurements demonstrates the predictive power of this scheme.

New absolute measurements of the viscosity of benzene, toluene, and m-xylene are presented. The measurements were performed in a recently developed vibrating-wire instrument, at temperatures of 303.15 and 323.15 K and pressures up to 80 MPa. The overall uncertainty in the reported viscosity data is estimated to be ±0.5%.

The design and operation of a new vibrating-wire viscometer for the measurement of the viscosity of liquids at pressures up to 100 MPa are described. The design of the instrument is based on a complete theory so that it is possible to make absolute measurements with an associated error of only a few parts in one thousand. Absolute measurements of the viscosity of n-hexane are reported at 298.15 K at pressures up to 80 MPa. The overall uncertainty in the reported viscosity data is estimated to be ±0.5%, an estimate confirmed by the comparison of values of viscosity of slightly inferior accuracy.

The sonochemical degradation of phenol, 2-chlorophenol and 3,4-dichlorophenol in aqueous solutions as a function of several operating conditions has been investigated. Experiments were performed at initial substrate concentrations of 0.1, 0.5 and 1 g l(-1), liquid phase volumes of 0.05, 0.07 and 0.08 l, electric power outputs of 125, 187.5 and 250 W, liquid bulk temperatures of 20, 35, 50 and 70 degrees C and an ultrasound frequency of 20 kHz. Substrate concentration was determined as a function of time by means of high performance liquid chromatography. At the conditions under consideration, the rate of degradation follows first order kinetics with respect to the substrate concentration and increases with increasing electric power and decreasing liquid volume. The relative reactivity appears to decrease in the order: 2-chlorophenol3,4-dichlorophenolphenol. Measurements of liquid phase total organic carbon content showed that degradation by-products are more recalcitrant than the original substrate. The rate of 2-chlorophenol degradation was also found to decrease with decreasing liquid bulk temperature and increasing initial concentration. Addition of t-butanol as a hydroxyl radical scavenger only partially inhibited degradation, thus implying that degradation is likely to proceed via both radical-induced and thermal reactions. Addition of Fe2+ ions at concentrations as low as about 0.2 x 10(3) g l(-1) resulted in increased degradation rates; this is attributed to iron being capable of readily decomposing hydrogen peroxide (generated by water sonolysis) in a Fenton-like process to form hydroxyl radicals as well as being an effective oxidation catalyst. The implications of the use of ultrasound in wastewater treatment are also discussed.

Discusses research on medical applications of nanotechnology in the European Union. Nanobiotechnology is based on the idea that the ability to design synthetic materials on a nanoscale base toward molecular architecture of biologically relevant molecules will ultimately lead to the integration of artificial and biological matter. This concept has applications in the environment, biomedical sensors, and artificial tissues. Biomaterials and medical devices represent a fast emerging market that is estimated at about US$260 billion worldwide, with Europe's share being about 30%. Biomaterial and tissue engineering research are of high quality and in strong competition with the United States, who is still the world leader. The biomimetic approach to developing advanced materials is a new field that provides different solutions to existing challenges. In all living organisms, nature produces a plethora of materials, architectures, systems, and functions, which have been optimized during a long and tough evolution process. An essential feature of these highly structured materials is their structural organization in many scales, as is the case of ceramics and composites found in animal shells or in bone and dental tissues.

Acoustic noise levels for fast MRI pulse sequences were surveyed on 14 systems with field strengths ranging from 0.2 T to 3 T. A microphone insensitive to the magnetic environment was placed close to the magnet isocenter and connected via an extension cable to a sound level meter outside the scan room. Measured noise levels varied from 82.5 +/- 0.1 dB(A) for a 0.23 T system to 118.4 +/- 1.3 dB(A) for a 3 T system. Further measurements on four of the closed-bore systems surveyed showed that: 1) pulse sequence parameters (particularly FOV and TR) were more influential in determining noise level than field strength, 2) the noise level was found to vary along the z-direction with a maximum near the bore entrance, and 3) in one of two systems tested there was a significant increase in noise with a volunteer present instead of a test object. The results underline the importance of hearing protection for patients and for staff spending extended periods in the scan room.

The attachment, proliferation, morphology, and differentiation of two cell types-skeletal muscle cells and chondrocytes-were investigated on different compositions of poly(ethylene glycol) and poly(butylene terephthalate) segmented block copolymers. Four weight percentages (40, 55, 60, and 70%) and two different molecular weights (300 and 1000 Da) of poly(ethylene glycol) were tested. Varying the weight percentage and molecular weight of poly(ethylene glycol) resulted in different behaviors for skeletal muscle cells and chondrocytes. The attachment of skeletal muscle was the highest (similar to tissue culture polystyrene) when copolymers containing 55 wt % of poly(ethylene glycol) were used, regardless of the poly(ethylene glycol) molecular weight. Maximum proliferation and differentiation of skeletal muscle cells was achieved when copolymers containing 55 wt % and 300 Da molecular weight of poly(ethylene glycol) were used. In contrast, the weight percentage and molecular weight of poly(ethylene glycol) had no significant effect on chondrocyte attachment and proliferation; the attached chondrocytes retained a differentiated phenotype only when a 70 wt % of poly(ethylene glycol) was used. Cell behavior was correlated with the surface properties of the copolymer films, as indicated by contact-angle measurements. These results suggest that an optimized wt % and molecular weight of poly(ethylene glycol) will be useful depending on the specific cell type.

After cardiovascular intervention, smooth muscle cells (SMC) are directly exposed to blood flow and thus their behavior might be affected by fluid hemodynamic forces. The aim of this study was to determine the effect of fluid shear stress on the growth rate of SMC. Human aortic smooth muscle cells (hASMC) were seeded on fibronectin-coated glass slides and were exposed to different levels of shear stress using parallel plate flow chambers. After 24 h, cell numbers in the stationary and sheared cultures were measured by a Coulter counter. Results demonstrated that increasing shear stress significantly reduces the proliferation rate of hASMC (P0.05). Comparable lactate dehydrogenase levels in the media of stationary and flow cultures provided evidence that the reduction of cell number was not due to cell injury. Proliferating cell nuclear antigen (PCNA) immunofluorescence studies indicated that the cell cultures were not growth arrested 24 h after exposure to shear stress, and that the differences in PCNA staining between stationary control and flow cultures were comparable to the cell counts.

This study emphasizes the importance of multicellular cultures in providing appropriate signals for vascular organization of skeletal tissues. Eucomed, the European Medical Technology Industry Association, represents directly and indirectly more than 3,500 business entities in Europe and beyond. The Eucomed mission is to create and maintain a suitable framework by enabling the manufacturers of medical technology and other related economic actors to operate, innovate, and market in an open and competitive marketplace, with the ultimate objective to improve the access of patients and clinicians to modern and reliable medical technology products. The paper shows a recent example of the role of Eucomed on the tissue engineering industry as illustrated in its response to the proposal of a regulation launched by the European Commission on 4 May 2005. The proposal covers human-tissue-engineered products, bringing them under the scope of medicinal products. Eucomed's position is that since human-tissue-engineering products are not medicinal products, they cannot be regulated by the existing, unchanged rules for medicinal products. Existing requirements for clinical investigation and for good manufacturing practices for medicinal products should be appropriately adapted from the technical point of view, while maintaining their general ethical requirements. Eucomed has also put forward suggestions to address the specificity of combination products, in particular hybrid products made of human-tissue-engineered products and medical devices.

The degradation of 2-chloropyridine in synthetic aqueous solutions by means of ultraviolet and ultrasound irradiation has been investigated. The effect of varying operating conditions (initial substrate concentrations from 100-500 mg/l, temperatures from 5-50°C and liquid volumes from 50-500 ml) on degradation efficiency was evaluated. Light irradiation was generally more effective than ultrasound-driven degradation and complete substrate removal could be achieved in relatively short treatment times. On the other hand, ultrasound efficiency could be improved coupling cavitation with the Fenton reagents and selecting optimal reaction temperatures. The kinetics of 2-chloropyridine photodegadation at the conditions in question was found to be first order with respect to substrate concentration with reaction rates increasing with increasing temperature and decreasing concentration and liquid volume. The extent of total organic carbon photodegradation was substantially lower than that of the substrate itself indicating the formation of relatively stable by-products.

The supply of donated organs and tissue that are used to treat diseases and disorders is far outnumbered by the need. Recently, there has been a lot of interest in the use of stem cells to treat such disorders, because these cells have a large proliferative potential while they can differentiate into every cell in the body under the appropriate stimuli. Recent reports on applications to Duchenne Muscular Dystrophy and myocardial infarction from the University of Pittsburgh and the University of Dusseldolf have provided some evidence that autologous or homologous stem cell transplantation could one day treat lethal human diseases. In addition to these uses of stem cells, there is research evidence that stem cells can be potentially used to treat spinal cord injury, burns, osteoarthritis, diabetes, Parkinson's and Alzheimer diseases. There are, however, many controversial issues, involving ethics, science, politics, and religion, associated with stem cell research from sacrificed human embryos.

The paper describes the progress made in the development of an instrument for the measurement of the thermal conductivity of molten materials at high temperatures. The instrument is designed to provide experimental data of unique accuracy at temperatures up to 1500 K on a wide range of materials, some of which will be suitable as standard reference substances. In particular, the paper concentrates upon the method of analysis of the experimental data and upon those critical aspects of the experimental technique which will enable a high accuracy to be achieved. Demonstrations of the validity of the method of treating one correction and of its behavior under typical conditions are included.