Gas-liquid dispersions in structured packing with high-viscosity liquids

Gas holdup in bubble columns containing structured packing was determined for varying liquid phase viscosity and different construction materials of the packing. Three columns, containing packing made from smooth nickel plate, perforated nickel plate and plastic sheets, respectively, were tested. The gas holdup in a column with no internals was also measured for comparison purposes. The effect of viscosity on gas holdup was studied by using water, aqueous glycerol and aqueous CMC solutions as the liquid phase; some of the solutions showed non-Newtonian behavior.The experimental results of gas void fraction were correlated in terms of superficial gas velocity and liquid viscosity through a simple homographic expression. The geometric characteristics of the structured packings were found to influence gas holdup, thus yielding slightly different equations for each structured packing. This effect is discussed in detail. Nevertheless, for engineering purposes a single equation representing all the data is also proposed, which permits the prediction of gas holdup in structured packing with sufficient accuracy.     

An in situ cell to study phase transitions in individual aerosol particles on a substrate using scanning transmission x-ray microspectroscopy

A new in situ cell to study phase transitions and chemical processes on individual aerosol particles in the x-ray transmission microscope at the PolLux beamline of the Swiss light source has been built. The cell is machined from stainless steel and aluminum components and is designed to be used in the standard mount of the microscope without need of complicated rearrangements of the microscope. The cell consists of two parts, a back part which contains connections for the gas supply, heating, cooling devices, and temperature measurement. The second part is a removable clip, which hosts the sample. This clip can be easily exchanged and brought into a sampling unit for aerosol particles. Currently, the cell can be operated at temperatures ranging from -40 to +50 °C. The function of the cell is demonstrated using two systems of submicron size: inorganic sodium bromide aerosols and soot originating from a diesel passenger car. For the sodium bromide we demonstrate how phase transitions can be studied in these systems and that O1s spectra from aqueous sodium bromide solution can be taken from submicron sized particles. For the case of soot, we demonstrate that the uptake of water onto individual soot particles can be studied.     

A Comparison of Resilient Overlay Multicast Approaches

Overlay-based multicast has been proposed as a key alternative for large-scale group communication. There is ample motivation for such an approach, as it delivers the scalability advantages of multicast while avoiding the deployment issues of a network-level solution. As multicast functionality is pushed to autonomous, unpredictable end systems, however, significant performance loss can result from their higher degree of transiency when compared to routers. Consequently, a number of techniques have recently been proposed to improve overlays' resilience by exploiting path diversity and minimizing node dependencies. Delivering high application performance at relatively low costs and under high degree of transiency has proven to be a difficult task. Each of the proposed resilient techniques comes with a different trade-off in terms of delivery ratio, end-to-end latency and additional network traffic. In this paper, we review some of these approaches and evaluate their effectiveness by contrasting the performance and associated cost of representative protocols through simulation and wide area experimentation.     

Genotype-phenotype association in infants with cystic fibrosis at the time of diagnosis

The relationship between the most common disease-causing mutations, the clinical manifestation, and lung function was prospectively assessed in 60 infants (33 females, 27 males) with cystic fibrosis at time of diagnosis (age: 7.2 months; range: 0.8-23.8 months). Lung function was assessed by infants whole-body plethysmography. Age at time of diagnosis was independent from the genotype. Weight gain from birth until the time of diagnosis expressed in percent predicted of a normal population was lower in the 3905insT group (57.9 +/- 19.0%) compared with deltaF508 homozygotes (62.5 +/- 20.6%; n.s.) and the R553X group (85.9 +/- 10.9%; p < 0.005). Differences regarding lung function within the genetic groups are mainly related to pulmonary hyperinflation, measured by thoracic gas volume (TGV), present in 8 of 9 infants with 3905insT, differentiating this frameshift mutation (TGV of 7.0 +/- 3.6 SD-S) from the R553X mutation (TGV 2.1 +/- 4.6 SD-S; p < 0.02). It is concluded that the variable disease findings in infants with cystic fibrosis is clinically and functionally reflected by features already present at time of diagnosis. The degree of pulmonary hyperinflation is, at least partly, influenced by the genotype.     

Accessing the scientific literature. The reality of virtual scholarship

OBJECTIVE: The purpose of this study was to evaluate HDL-C values and their relationship to high total cholesterol values during childhood. PATIENTS AND METHODS: We have studied 4,547 children and adolescents of both sexes between 4 and 6 years of age. RESULTS: We found HDL-C values > 50, 65 and 75 mg/dl in 66.28%, 26.17% and 7.81%, respectively. Of the cases studied, 44.8% had TC > 174.9 mg/dl and 15.17% higher than 199.9 mg/dl. The positive predictive value (PPV) to detect LDL-C > 129.9 mg/dl was 67.1 and 26.4 for values of TC > 199.9 and 174.9, respectively. The PPV to detect a LDL-C/HDL-C > 2.19 of the TC > 199.9 and 174.9 mg/dl was 54.78 and 23.95, respectively. CONCLUSIONS: The HDL-C of children and adolescents is often high and this could be responsible for the high TC values. Most of the children with TC values between 174.9 and 199.9 mg/dl have neither an increase in LDL-C nor in the LDL-C/HDL-C ratio.     

Schematic-Driven Substrate Noise Coupling Analysis in Mixed-Signal IC Designs

This paper presents an approach to reduce substrate cross-talk noise between noisy and sensitive circuitry in mixed-signal integrated circuits at different stages of design and layout development. Silencer! a new, fully automated, schematic-driven substrate noise coupling analysis tool is introduced to accomplish this task. The tool seamlessly enables substrate noise coupling analysis in a standard mixed-signal design flow. Two different methods, fast scalable macro-models and a boundary element solver are integrated into Silencer!. These methods allow extractions of a substrate network from geometric layout information. Simulation results obtained with Silencer! are accurate to within 10% of measured integrated circuits