Application of space periodic variation of light polarization in imaging polarimetry

The application of space periodic variation of light polarization for measurement and calculation of the distribution of the phase retardation between two eigenwaves propagating inside a linearly birefringent media and the distribution of the azimuth angle of the first eigenvector is described. The measuring method proposed does not require any mechanical movements or rotations of any optical elements. Application of a liquid crystal (LC) modulator instead of a quarter-wave plate gives an opportunity to introduce the required phase shift. The space periodic modulation of the polarization of light is achieved by the use of a Wollaston prism placed inside the path of the light beam. Then a fast Fourier transform is used for further calculations. The number of measurements of the light intensity at the output of the system is minimized to two. These assumptions make the proposed method very fast, which is especially important in measurements of the objects with optical anisotropy that is changing in time.     

The effect of organic loading on process performance and membrane fouling in a submerged membrane bioreactor treating municipal wastewater

The results of experiments on municipal wastewater primary effluent are presented for a pilot-scale submerged membrane bioreactor (SMBR). The SMBR pilot plant employed an ultrafiltration membrane with a nominal pore size of 0.035 microm and was operated at a constant membrane flux of 30 L/m(2)h. The mixed liquor suspended solids (MLSS) concentration was maintained at 8+/-2 g/L and steady-state fouling rates were determined for 10, 5, 4, 3, and 2-d MCRTs, corresponding to food-to-microorganism (F/M) ratios of 0.34, 0.55, 0.73, 0.84, and 1.41 gCOD/gVSS d, respectively. Membrane fouling rates increased as the F/M was increased. Steady-state membrane fouling rates were correlated with total soluble microbial products (SMP) concentrations. The membrane fouling rates did not correlate well with soluble COD measured on a 0.45 microm membrane filtrate of mixed liquor or with soluble COD rejection (effluent COD/soluble COD).     

Numerical determination and experimental verification of the optimum autofrettage pressure for a complex aluminium high‐pressure valve to foster crack closure

The determination of the optimum autofrettage pressure enables a clear improvement of the fatigue life for an internally highly pressurized component. The autofrettage process induces residual compressive stress after the release of a single static overload pressure, leading to plastic deformation at the inner wall whereas the outer part is only elastically stressed. This autofrettage pressure is clearly above the subsequent pulsating operating pressure range. Due to the complex geometry of the aluminium valve body, a detailed elastic–plastic finite element analysis is used to determine the critical area and the optimum autofrettage pressure. Based on an experimental stress–strain curve, three important load steps are simulated in a non‐linear way. The FKM guideline is used to assess fatigue life and crack initiation with detailed subsequent experimental verification. Even if small cracks occur, residual compressive stresses prohibit crack growth (nonpropagating crack), which can be analytically verified by fracture mechanical considerations (crack closure effect).     

Formation and stabilization of combustion-generated environmentally persistent free radicals on an Fe(III)2O3/silica surface

Previous studies have shown environmentally persistent free radicals (EPFRs) form when chlorine- and hydroxy-substituted benzenes chemisorb on Cu(II)O-containing surfaces under postcombustion conditions. This paper reports the formation of EPFRs on silica particles containing 5% Fe(III)(2)O(3). The EPFRs are formed by the chemisorption of substituted aromatic molecular adsorbates on the metal cation center followed by electron transfer from the adsorbate to the metal ion at temperatures from 150 to 400 °C. Depending on the nature of the adsorbate and the temperature, two organic EPFRs were formed: a phenoxyl-type radical, which has a lower g-value of 2.0024-2.0040, and a second semiquinone-type radical, with a g-value of 2.0050-2.0065. Yields of EPFRs were ～10× lower for iron than copper; however, the half-lives of EPFRs on iron ranged from 24 to 111 h, compared to the half-lives on copper of 27 to 74 min. The higher oxidation potential of Fe(III)(2)O(3) is believed to result in greater decomposition of the adsorbate, resulting in the lower EPFR yields, but increased stabilization of the EPFR once formed, resulting in the longer half-lives.     

Infiltration of highly aligned carbon nanotube arrays with molten polystyrene

Highly aligned carbon nanotube/polystyrene (HACNT/PS) composites were prepared conveniently via polymer impregnation of aligned arrays, avoiding conventional solution or melt processes that involve high-shear blending. Detailed scanning electron microscopy (SEM), X-Ray diffraction (XRD) and differential scanning calorimetry (DSC) studies show that the alignment of the multi-wall nanotubes is retained after polymer impregnation. A range of key parameters were investigated, including the amount of molten polymer required for complete infiltration, the maximum mass fraction of CNTs in dense composites, and the effect of CNTs on the glass transition temperature (T_g) of the polymer. This approach may be adapted to the fabrication of large scale, highly anisotropic, thin or multilayer CNT composites using other molten polymers.     

Absorbing the Rapid Growth of Shopping Centres in Poland after the Political Change

The aim of this paper is to present the development of shopping centres in Poland after its political transition. From that time, all types of shopping centres were built, starting from the very basic first generation and developing into the most current formats. In the article, types of shopping centres are compared to their western origins. Planning laws and procedures that apply to the processes are also described, with an example of a law that was introduced to specifically control growth of shopping centres. Apart from that current trends and growth possibilities in the present market situation are discussed. As a result, a very rapid development process was observed, with little hampering from the planning policies. This may be used as a point of reference for other countries that have not yet encountered that process.     

Pruning backpropagation neural networks using modern stochastic optimisation techniques

Approaches combining genetic algorithms and neural networks have received a great deal of attention in recent years. As a result, much work has been reported in two major areas of neural network design: training and topology optimisation. This paper focuses on the key issues associated with the problem of pruning a multilayer perceptron using genetic algorithms and simulated annealing. The study presented considers a number of aspects associated with network training that may alter the behaviour of a stochastic topology optimiser. Enhancements are discussed that can improve topology searches. Simulation results for the two mentioned stochastic optimisation methods applied to non-linear system identification are presented and compared with a simple random search.     

Synthesis of solid epoxy resins base on BPC II and bisphenol A using conventional heating equipment and microwave

New solid state epoxy resins based on diglycidyl ether of 1,1‐dichloro‐2,2 bis (4‐hydroxyphenyl), ethylene (BPC) and BPA epoxy resins in the reaction with BPC and BPA were developed. Solid epoxy resins were synthesised by the use of two different heating methods: conventional and microwave reactor. The use of microwave radiation as novel heating medium as an alternative to the conventional methods, which provide a quicker and more effective synthesis. The solid epoxies have high melting points higher than 100°C and the polycondensation degree remains between n = 4–12. Epoxy value stays low and occurs around 0,02–0,1. BPA epoxy resins and diglycidylether of BPC II were compared in terms of reaction speed. It can be seen that the reaction of BPC diglycidylether occurs approximately 20% quicker given the same reaction conditions of temperature, and balance of catalyst. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3850–3854, 2006     

Influence of nanoparticles of platinum on chicken embryo development and brain morphology

Platinum nanoparticles (NP-Pt) are noble metal nanoparticles with unique physiochemical properties that have recently elicited much interest in medical research. However, we still know little about their toxicity and influence on general health. We investigated effects of NP-Pt on the growth and development of the chicken embryo model with emphasis on brain tissue micro- and ultrastructure. The embryos were administered solutions of NP-Pt injected in ovo at concentrations from 1 to 20 μg/ml. The results demonstrate that NP-Pt did not affect the growth and development of the embryos; however, they induced apoptosis and decreased the number of proliferating cells in the brain tissue. These preliminary results indicate that properties of NP-Pt might be utilized in brain cancer therapy, but potential toxic side effects must be elucidated in extensive follow-up research.     

DQF-MT MRI of connective tissues: application to tendon and muscle

Object

The sequence combining DQF (double quantum filtering) with magnetisation transfer (DQF-MT) was tested as an alternative to the DQF sequence for characterising tendon and muscle by MR imaging.

Materials and methods

DQF-MT images of tendon–muscle phantoms were obtained at 4.7 T using ultra-short time to echo (UTE) methods in order to alleviate the loss of SNR due to the short T₂ of the tissues. Two different sampling schemes of the k-space, Cartesian or radial, were employed. In vivo images of the human ankle on a clinical 1.5 T scanner are also presented. Parameters providing optimal tendon signal as well as optimal contrast between this tissue and muscle were determined.

Results

Two sets of parameters resulting in different contrasts between the tissues were found. For the first set (short creation time τ = 10 μs and magnetisation exchange time t _LM = 100 ms), DQF-MT signals in muscle and tendon were detected, with that of the tendon being the larger one. For the second set (long creation time τ = 750 μs and magnetisation exchange time 10 μs < t _LM < 100 ms), the DQF-MT signal was detected only in the tendon, and the decay of the double quantum coherence was slower than that observed for the first one, which allowed us to acquire DQF-MT MR images on a clinical 1.5 T MR scanner with minimal software interventions. In favourable conditions, the DQF-MT signal in the tendon could represent up to 10 % of the single-quantum signal.

Conclusion

Dipolar interaction within macromolecules such as collagen and myosin is at the origin of the DQF-MT signal observed in the first parameter set. This should enable the detection of muscle fibrosis.