Woven graphite fiber structures for use in ultra-light weight heat exchangers

Lightweight, robust woven graphite-fiber structures were developed for heat exchangers which provide high conductivity paths along the direction of the graphite fibers. These structures were produced and characterized for air permeability/pressure drop and thermal (heat transfer) performance. Results indicate that the materials are suitable for use in ultra-light weight heat exchanger applications such as vehicle radiators or other areas where light weight, compact, conformable heat transfer devices are needed.     

An integrated high voltage digital-to-analog converter for a reconfigurable antenna array

This paper presents an integrated high voltage digital-to-analog converter, which is fabricated in a 0.35 \({\upmu }\) m high voltage CMOS technology (AMS H35), and can be applied in high voltage applications up to 115 V. The high voltage output is controlled by 8-bit digital input code. In order to improve the accuracy and decrease the required area, it is implemented by a low voltage DAC and a high voltage amplifier for boosting the controllable output voltage. Since the current consumption from the high voltage power supply is only 80 \({\upmu }\) A, it can be powered by a charge pump which generates 115 V from a battery with 3.7 V DC. Combining with a 8*8 external high voltage switch array, the proposed high voltage digital-to-analog converter can drive up to 64 individual channels of antenna array with a voltage from 0 to 115 V. It will greatly reduce the complexity and cost of mobile applications which use tunable microwave devices and require high voltages. The feasibility is proved by post-simulation result and experimental test result. The proposed concept of the high voltage ASIC is also proved by a demonstrator.     

Applications of the multidimensional equations to complex fuel assembly problems

For the analysis of reactors with complex fuel assemblies or fine mesh applications as pin by pin neutron flux reconstruction, the usual approximation of the neutron transport equation by the multigroup diffusion equation does not provide good results. A classical approach to solve the neutron transport equation is to apply the spherical harmonics method obtaining a finite approximation known as the P_L equations. In this line, a nodal collocation method for the discretization of these equations on a rectangular mesh is used in this paper to analyse reactors with MOX fuel assemblies. Although the 3D P_L nodal collocation method becomes feasible due to the improvements in computer hardware, a complete treatment of the detailed structure of the fuel assemblies in actual three-dimensional geometry is still prohibitive, thus, an assembly homogenization method is necessary. A homogenization method compatible with our multidimensional P_L code is proposed and tested performing heterogeneous and homogenized calculations. In this work, we apply the method to 2D complex fuel assembly configurations.     

Probiotics in Goat Milk Products: Delivery Capacity and Ability to Improve Sensory Attributes

Dairy foods, particularly those of bovine origin, are the predominant vehicles for delivery of probiotic bacteria. Caprine (goat) milk also possesses potential for successful delivery of probiotics, and despite its less appealing flavor in some products, the use of goat milk as a probiotic carrier has rapidly increased over the last decade. This review reports on the diversity, applicability, and potential of using probiotics to enhance the sensory properties of goat milk and goat milk‐based products. A brief conceptual introduction to probiotic microorganisms is followed by an account of the unique physicochemical, nutritive, and beneficial aspects of goat milk, emphasizing its advantages as a probiotic carrier. The sensory properties of probiotic‐enriched goat milk products are also discussed. The maintenance of probiotic viability and desirable physicochemical characteristics in goat milk products over shelf life is possible. However, the unpleasant sensory features of some goat milk products remain a major disadvantage that hinder its wider utilization. Nevertheless, certain measures such as fortification with selected probiotic strains, inclusion of fruit pulps and popular flavor compounds, and production of commonly consumed tailor‐made goat milk‐based products have potential to overcome this limitation. In particular, certain probiotic bacteria release volatile compounds as a result of their metabolism, which are known to play a major role in the aroma profile and sensory aspects of the final products.     

Safety assessment of dairy microorganisms: the Lactococcus genus

The Lactococcus genus includes 5 species. Lactococcus lactis subsp. lactis is the most common in dairy product but L. garviae has been also isolated. Their biotope is animal skin and plants. Owing to its biochemical characteristics, strains of L. lactis are widely used in dairy fermented products processing. Cases of human infections due to lactococci are very seldom reported even if Lactococcus garviae can be involved in fish diseases. Then L. lactis can be considered as safe and it is most commonly considered as Generally Recognized as Safe.     

Analysis of pressure signals using a Singular System Analysis (SSA) methodology

Pressure signals are used for control and monitoring the safety in nuclear power plants. These pressure transmitters are tested periodically. In particular, we are only interested in the transmitters checked to analyse the response times. The noise analysis is a very efficient tool to obtain adequate response times, but although this method can produce accurate results if performed properly, inherent problems in the tests can produce invalid results, for example if the test signal is oscillatory. An approach to remove the oscillatory contamination contribution from the pressure transmitter signal is the Singular Spectrum Analysis (SSA). This method is based on the fact that the dynamics associated with the signal can be described statistically in a linear way by its principal axes.

Many or most directions in the embedding space can be associated with noise and typically a small number of these principal directions can explain the main dynamic characteristics of the signal; these principal directions are related with the singular values of the correlation matrix signal.

This methodology has been applied successfully to several pressure signals of a typical Pressurized Water Reactor which show an oscillatory contribution of 0.6 Hz. The SSA method removes this oscillatory contamination very efficiently.     

Optimization of sucrose phosphorylase production by Leuconostoc mesenteroides

Environmental optimization of the Leuconostoc mesenteroides ATCC 12291 sucrose phosphorylase fermentation process was undertaken. The effects of pH control, fermentation temperature and medium composition on growth, culture viscosity, sucrose utilization pattern and dynamics of enzyme fermentation were studied. Optimized fermentations were run at controlled pH 7 at 32°C yielding high enzyme levels. Applications of sucrose phosphorylase are discussed.     

Visual stimulation facilitates penile responses to vibration in men with and without erectile disorder.

This study compared reflexogenic and psychogenic penile responses in men with and without erectile disorder. It was hypothesized that men with psychogenic erectile dysfunction respond minimally to vibrotactile stimulation. An enhancement of penile responses was expected when vibration was combined with erotic film. Patients were 50 men with psychogenic erectile dysfunction, 45 men with organic erectile dysfunction, and 50 sexually functional men. The combination of film and vibration resulted in stronger penile responses than the stimuli presented separately. Men with psychogenic erectile dysfunction and sexually functional men did not differ in responses to film and film-and-vibration conditions. As predicted, responses of the 2 groups were different in the vibration condition. Interpretations are provided in terms of attention and appraisal. The findings are relevant to the development of psychophysiological diagnostic procedures. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Biomagnification of organic pollutants in benthic and pelagic marine food chains from the Baltic Sea

The trophic transfer of organic pollutants with varying physical chemical properties was determined in both a pelagic and benthic food chain using delta 15N as a continuous variable for assessing trophic levels. The trophic transfer of organic pollutants through the entire food chain in terms of food chain magnification factors (FCMFs) was quantified from the slope of the regression between ln [concentration] and delta 15N. Organic pollutants with statistically significant FCMFs >1 were considered to biomagnify within the food chain, whereas those with FCMFs <1 were considered to trophically dilute. Statistically significant FCMFs >1 were found for PCB congeners and organochlorine pesticides in the Baltic food chains whereas statistically significant FCMFs <1 were found for PAHs and PCNs due to trophic dilution resulting from metabolism. FCMFs were generally greater in the pelagic food chain than in the benthic food chain. However, estimated FCMFs for the benthic food chain are likely in error, as the delta 15N method suggested a food chain structure which was not consistent with the known dietary patterns of the species. Biomagnification factors (BMFs) were additionally calculated as the ratio of the lipid normalized concentrations in the predator and prey species with adjustment for trophic level and were generally consistent with the FCMFs with BMF >1 for PCBs and organochlorines.     

Development of a finite volume inter-cell polynomial expansion method for the neutron diffusion equation

Heterogeneous nuclear reactors require numerical methods to solve the neutron diffusion equation (NDE) to obtain the neutron flux distribution inside them, by discretizing the heterogeneous geometry in a set of homogeneous regions. This discretization requires additional equations at the inner faces of two adjacent cells: neutron flux and current continuity, which imply an excess of equations. The finite volume method (FVM) is suitable to be applied to NDE, because it can be easily applied to any mesh and it is typically used in the transport equations due to the conservation of the transported quantity within the volume. However, the gradient and face-averaged values in the FVM are typically calculated as a function of the cell-averaged values of adjacent cells. So, if the materials of the adjacent cells are different, the neutron current condition could not be accomplished. Therefore, a polynomial expansion of the neutron flux is developed in each cell for assuring the accomplishment of the flux and current continuity and calculating both analytically. In this polynomial expansion, the polynomial terms for each cell were assigned previously and the constant coefficients are determined by solving the eigenvalue problem with SLEPc. A sensitivity analysis for determining the best set of polynomial terms is performed.