Fluidized bed electrowinning of zinc from chloride electrolytes

The fluidized bed electrowinning of zinc from chloride electrolytes has been studied in a laboratory cell. The cell was operated at superficial current densities in the range 1200–7500 A/m² with catholytes containing up to 62 kg/m³ Zn and up to 28 kg/m³ HCl. Anolytes examined contained 58 kg/m³ NaCl and up to 100 kg/m³ HCl and, in some instances, had the same composition as the catholyte. Both “pure” catholytes and ones with deliberate additions of impurities (Ni, Co and Sb) were used. Pure solutions yielded current efficiencies and power consumptions comparable to or better than those of cells with conventional electrodes. Antimony (particularly in combination with Ni and Co) had a detrimental effect on cell performance; this detrimental effect was largely alleviated by simultaneous additions of glue.     

What Do the Data Say?

For too long now the statistical analysis of data has been a slave to the behavioral paradigm. Because many psychologists choose not to adhere to that particular outlook, it would be desirable to have a different way of discovering what the data are trying to tell us. One different method would be to discard the deterministic model, to eschew the conceptualization that the data are controlled by independent variables. Pursuant to this suggestion, a new way of analyzing data is now being proposed, existential statistics. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cyclic, low-dose total body irradiation for metastatic neuroblastoma

Total body irradiation (TBI) can be thought of as a systemic anticancer agent. It therefore might best be given like an adjuvant drug, i.e. in tolerable doses, cyclically. The therapeutic ration between normal bone marrow stem cells and suitably sensitive cancer cells should be widened by these means. Fourteen children with advanced (State IV) neuroblastomas were given 100-150 rad TBI in 50 rad daily fractions along with each three-week cycle of standard triple-agent chemotherapy, (vincristine, DTIC, cyclophosphamide). Two patients died of toxicity and one is still undergoing therapy. Four of the remaining 12 survive free of disease for 12+ to 31+ months. The regimen is well tolerated, but prolonged, pronounced bone marrow depression, especially thrombocytopenia, comonly occurs after doses of 300-450 rad.     

Predicting the stereochemistry of diphenylphosphino benzoic acid (DPPBA)-based palladium-catalyzed asymmetric allylic alkylation reactions: a working model

Palladium-catalyzed asymmetric allylic alkylation has proven to be a powerful method for the preparation of a wide variety of chiral compounds and the rapid assembly of complex molecular architecture from simple starting materials. While many types of catalyst systems have been successfully employed with certain systems, diphenylphosphino benzoic acid (DPPBA) based ligands have found use over a broad range of substrate classes. This Account highlights the mechanistic aspects considered when designing reactions with DPPBA-based ligands and presents a working model for the a priori prediction of their stereochemical outcome.     

Gamma bang time analysis at OMEGA

Absolute bang time measurements with the gas Cherenkov detector (GCD) and gamma reaction history (GRH) diagnostic have been performed to high precision at the OMEGA laser facility at the University of Rochester with bang time values for the two diagnostics agreeing to within 5 ps on average. X-ray timing measurements of laser-target coupling were used to calibrate a facility-generated laser timing fiducial with rms spreads in the measured coupling times of 9 ps for both GCD and GRH. Increased fusion yields at the National Ignition Facility (NIF) will allow for improved measurement precision with the GRH easily exceeding NIF system design requirements.     

GEANT4 simulations of Cherenkov reaction history diagnostics

This paper compares the results from a GEANT4 simulation of the gas Cherenkov detector 1 (GCD1) with previous simulations and experimental data from the Omega laser facility. The GCD1 collects gammas emitted during a deuterium-tritium capsule implosion and converts them, through several processes, to Cherenkov light. Photon signals are recorded using subnanosecond photomultiplier tubes, producing burn reaction histories. The GEANT4 GCD1 simulation is first benchmarked against ACCEPT, an integrated tiger series code, with good agreement. The simulation is subsequently compared with data from the Omega laser facility, where experiments have been performed to measure the effects of Hohlraum materials on reaction history signals, in preparation for experiments at the National Ignition Facility.     

2D soft x-ray system on DIII-D for imaging the magnetic topology in the pedestal region

A new tangential two-dimensional soft x-ray imaging system (SXRIS) is being designed to examine the edge island structure in the lower X-point region of DIII-D. Plasma shielding and/or amplification of the calculated vacuum islands may play a role in the suppression of edge-localized modes via resonant magnetic perturbations (RMPs). The SXRIS is intended to improve the understanding of three-dimensional (3D) phenomena associated with RMPs. This system utilizes a tangential view with a pinhole imaging system and spectral filtering with beryllium foils. SXR emission is chosen to avoid line radiation and allows suitable signal at the top of a H-mode pedestal where T(e)～1-2?keV. A synthetic diagnostic calculation based on 3D SXR emissivity estimates is used to help assess signal levels and resolution of the design. A signal-to-noise ratio of 10 at 1 cm resolution is expected for the perturbed signals, which are sufficient to resolve most of the predicted vacuum island sizes.     

Enhanced Terahertz Receiver Using a Distributed Bragg Reflector Coupled to a Photoconductive Antenna

We report the use of a terahertz (THz) receiver fabricated using a photoconductive antenna mounted upon a distributed Bragg reflector (DBR). It is shown that the relative performance of the device is in accordance with the reflectivity curves of the DBR. At maximum reflectivity the device improved upon the reference THz signal by up to 30%. In addition, we characterize the saturation of the device with laser pump power and it is shown that the device exhibits an improved optical efficiency when compared to the reference receiver.     

Describing Network Traffic Using the Index of Variability

Commonly used measures of traffic burstiness do not capture the fluctuation of traffic variability over the entire range of time-scales. In this paper, we present a measure of variability, called the Index of Variability (Hv(tau)), that depicts the degree of variability (burstiness) of a typical network traffic process at each time-scale and is analytically tractable for many traffic models. As an illustration, we derive the closed-form expressions of Hv(tau) for two traditional traffic models and generate a variety of two-dimensional (2D) and three-dimensional (3D) Index-of-Variability curves. These curves demonstrate that the Index of Variability can help in determining the complexities of the network traffic variability over the network performance relevant time-scales. We then introduce a practical method for estimating the Index-of-Variability curve from a given traffic trace. Using this method, we estimate the Index-of-Variability curves for 12 long NLANR network traffic traces. The results indicate that the variability of real network traffic varies with time-scales and that the Index of Variability has the ability to discern qualitative differences between traffic traces obtained from different networks. Thus, the Index of Variability offers the potential to gain insights into the dynamics of network traffic that existing tools do not offer.     

Shaping futures: A dialogue on chemical engineering education

Engineering as a discipline, profession, practice, and area of study continues to add substantial value in an increasingly complex world. With continually evolving complexity around the planet, such as the need for massive energy transition, global health technologies, or sustainable food systems, how might engineering education practices and theory be considered within these rapid and necessary changes? This paper presents an experiment of co-creation through experiential reflection about the state of chemical engineering education. Four chemical engineering professors engaged in a dialogue, facilitated by a researcher in education, through collaborative and actionable research. This dialogue uncovered innovative possibilities, educational themes, experiences, and opportunities for others in the profession to consider. The process of dialogue also encouraged the development of an imaginative future sense-making, known as futuring, through a collective experience. The findings reveal instructive perspectives on the shape of chemical engineering education that should be of value not only to engineers, but also other professionals, practitioners, or those in various science, technology, and math fields.