Perceived Air Quality,Sick Building Syndrome (SBS) Symptoms and Productivity in an Office with Two Different Pollution Loads

Abstract Perceived air quality, Sick Building Syndrome (SBS) symptoms and productivity were studied in an existing office in which the air pollution level could be modified by introducing or removing a pollution source. This reversible intervention allowed the space to be classified as either non-low-polluting or low-polluting, as specified in the new European design criteria for the indoor environment CEN CR 1752 (1998). The pollution source was a 20-year-old used carpet which was introduced on a rack behind a screen so that it was invisible to the occupants. Five groups of six female subjects each were exposed to the conditions in the office twice, once with the pollution source present and once with the pollution source absent, each exposure being 265 min in the afternoon, one group at a time. They assessed the perceived air quality and SBS symptoms while performing simulated office work. The subject-rated acceptability of the perceived air quality in the office corresponded to 22% dissatisfied when the pollution source was present, and to 15% dissatisfied when the pollution source was absent. In the former condition there was a significantly increased prevalence of headaches (P= 0.04) and significantly lower levels of reported effort (P=0.02) during the text typing and calculation tasks, both of which required a sustained level of concentration. In the text typing task, subjects worked significantly more slowly when the pollution source was present in the office (P=0.003), typing 6.5% less text than when the pollution source was absent from the office. Reducing the pollution load on indoor air proved to be an effective means of improving the comfort, health and productivity of building occupants.     

Surface modification of cellulose fibers. I. Spectroscopic characterization of surface-modified cellulose fibers and their copolymerization with styrene

Two coupling agents based on trichloro-s-triazine with different terminal unsaturated groups were synthesized in order to improve the bonding between cellulose fibers and an unsaturated polyester matrix. The products of the reactions between hydroxyl groups of cellulose and reactive species of coupling agents were analysed by Fourier-transform infrared spectroscopy (FTIR) and by elemental microanalyses. ESCA was used for surface characterization of treated fibers. The coupling agents were found to be concentrated on the fiber surface. Polymerization of styrene was carried out in the presence of treated fibers. That the unsaturated groups of the treated fibers were able to copolymrize with styrene was shown by FTIR. Further evidence of the presence of grafted polystyrene on the surfaces of the cellulose fibers was provided by ESCA measurements.     

Evaluation of Discretisation and Integration Methods for the Analysis of Hydrodynamic Bearings With and Without Surface Texturing

Surface texturing has been demonstrated to improve tribological performance of hydrodynamic bearings. Because the texturing increases complexity of a surface, numerical methods are required. However, no comparison study has so far been conducted to determine which methods are most accurate with the least number of grid/mesh points. Knowing this would allow for the analysis and optimisation of bearings with complex geometries. In this work, performance of four discretisation methods (finite difference, finite element, finite volume and spectral element (SE)) in approximating the pressure function and three integration methods (Newton–Cotes formulas and Gauss quadrature) in approximating the load capacity, coefficient of friction and film height was evaluated in a systematic manner. Three slider bearing geometries were used: inclined surface without texturing and two parallel surfaces textured with trapezoidal and quadratic dimples. For the evaluation, pressure function, load capacity, coefficient of friction were calculated analytically using the Reynolds equation. Differences between the analytical values and their approximations produced by the numerical methods were calculated versus the number of grid/mesh points. The numbers of points were determined for the differences below 5, 1 and 0.1 %. Results showed that the SE method and the Gauss quadrature were most accurate regardless of the bearing geometry and used up to 28 times fewer points as compared to other methods.     

Framework for application management with dynamic aspects J-EARS case study

The cost of computer system maintenance rises together with the increasing complexity of such systems. The use of an autonomic system architecture saves money by delegating some forms of maintenance to the systems themselves. The aim of this paper is to describe the results of creating a tool which introduces elements of adaptivity to Java applications using dynamic aspects. The impact of introducing aspects on the performance of various Application Servers is also discussed. Finally, benefits and problems arising from the use of the tool are presented, basing on sample use cases.     

Magnetic Properties of Nickel–Zinc Ferrite Toroids Prepared from Nanoparticles

Toroids comprised of silica-coated 10 nm diameter nickel–zinc (Ni–Fe) ferrite nanoparticles (Ni_0.5Zn_0.5Fe₂O₄) have been fabricated by careful control of both the coating process and subsequent densification by viscous sintering. A narrow processing window is identified between a maximum temperature at which the nanoparticles coarsen, losing their super-paramagnetic properties, and a lower temperature required for viscous flow densification. Key to the successful fabrication was drying and cold isostatic pressing of the silica-coated nanoparticles; other routes invariably led to cracking during either drying or sintering. The super-paramagnetic blocking temperature, the coercive field, and remanent magnetization could all be controlled over a wide range by varying the thickness of the silica coating from 1 to 15 nm. The dipole–dipole coupling distance is estimated to be 4 nm. The high-frequency (1–500 MHz) properties were sensitive to the sintering temperature as well as the thickness of the silica coating. Toroids sintered at 1000°C or less exhibited no high-frequency magnetic losses and their permeability decreased with increasing temperature, suggesting that the permeability was controlled by thermally activated magnetization relaxation.     

An integrated multichannel waveform generator for large-scale spatio-temporal stimulation of neural tissue

We present an ASIC designed for electrical stimulation of neural tissue using multielectrode arrays. The ASIC is foreseen for applications in systems that require simultaneous stimulation and recording of signals from various types of neural tissue, both in vitro and in vivo. The developed ASIC comprises 64 independent stimulation channels, which are capable to generate arbitrarily defined bipolar current or voltage waveforms, controlled in real time with time resolution of 12.5 μs and amplitude resolution of 7 bits. The amplitude range of output signal can be scaled over a very wide range, which ensures compatibility with various electrode arrays of different size and geometry. Each channel is also equipped with a stimulation artifact suppressor controlled in real time, which reduces the dead time of the system after each stimulation pulse.     

The profile of volatile compounds and polyphenols in wines produced from dessert varieties of apples

The aim of this study was to determine the influence of apple variety (Šampion, Idared and Gloster) on the polyphenol profile, volatile composition and sensory characteristics of apple wines. Apples were harvested from the orchard in Garlica Murowana (Poland) and the experiments were conducted on a laboratory scale. Statistically significant differences were detected in the chemical composition of the analyzed wines. The highest antioxidant activity was found in Šampion wines, which was associated with a relatively high concentration of chlorogenic acid and procyanidins. These samples also contained high amounts of acetaldehyde, ethyl acetate and methanol. Idared wines showed a similar polyphenol profile, but they had lower antioxidant capacity and were characterized by a high level of butanol and acetic acid. Gloster wines were distinguished from other samples by a lower concentration of polyphenols and higher concentration of fusel alcohols. During sensory evaluation, wines produced from Idared apples scored the highest value for overall quality.