Measurement of helium isotopes in soil gas as an indicator of tritium groundwater contamination

The focus of this study was to define the shape and extent of tritium groundwater contamination emanating from a legacy burial ground and to identify vadose zone sources of tritium using helium isotopes (3He and 4He) in soil gas. Helium isotopes were measured in soil-gas samples collected from 70 sampling points around the perimeter and downgradient of a burial ground that contains buried radioactive solid waste. The soil-gas samples were analyzed for helium isotopes using rare gas mass spectrometry. 3He/4He ratios, reported as normalized to the air ratio (RA), were used to locate the tritium groundwater plume emanating from the burial ground. The 3He (excess) suggested that the general location of the tritium source is within the burial ground. This study clearly demonstrated the efficacy of the 3He method for application to similar sites elsewhere within the DOE weapons complex.     

Enhanced mixture analysis of poly(ethylene glycol) using high-field asymmetric waveform ion mobility spectrometry combined with fourier transform ion cyclotron resonance mass spectrometry

The combination of high-field asymmetric waveform ion mobility spectrometry (FAIMS) with Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) makes possible lower detection limits, increased sensitivity, and increased dynamic range in the analysis of poly(ethylene glycol) (PEG) samples of low molecular weight. The signal gain obtained using FAIMS depends on ion identity, with a range between 1.8x and 14x obtained for various molecular ions of PEG 600. A 1.7-fold reduction in noise is obtained using FAIMS due to the elimination of chemical noise. The improved detection performance is predominantly due to a reduction in adverse Coulomb effects as a result of ions being selectively introduced into the mass spectrometer. The high ion transmission obtained using FAIMS combined with the high sensitivity of FTICR-MS detection make possible separation of multiple gas-phase conformers of PEG molecular cations that have low abundance (less than 0.2% relative abundance) and that have not been detected previously. Mixed dications of PEG that have the same nominal mass but differ by the number polymer subunits (m/Delta m up to 25,000) can be separately introduced into the mass spectrometer using FAIMS. Interactions of the carrier gas with the metal ions that are attached to the PEG molecules appear to be the most significant factor in these FAIMS separations.     

Delayed onset of photochromism in molybdenum oxide films caused by photoinduced defect formation

We report the photochromic properties of amorphous MoO₃ films deposited by dc sputtering with different O₂ flow rates. The kinetics of film coloration under UV light irradiation is determined using optical transmission spectroscopy. Changes in the absorbance and refractive index were derived from the analysis of transmittance spectra. The absorbance spectra exhibited a growing broad peak centered around 830 nm, which was induced by the UV irradiation. In the early stages of irradiation, the absorbance of the films did not change but their refractive indices did change. This induction time was correlated with the O₂ partial pressure during the film deposition, which was controlled by the O₂ flow rate. The origins of this observation are discussed.     

Integrated Workflow for the Label-Free Isolation and Genomic Analysis of Single Circulating Tumor Cells in Pancreatic Cancer

As pancreatic cancer is the third deadliest cancer in the U.S., the ability to study genetic alterations is necessary to provide further insight into potentially targetable regions for cancer treatment. Circulating tumor cells (CTCs) represent an especially aggressive subset of cancer cells, capable of causing metastasis and progressing the disease. Here, we present the Labyrinth–DEPArray pipeline for the isolation and analysis of single CTCs. Established cell lines, patient-derived CTC cell lines and freshly isolated CTCs were recovered and sequenced to reveal single-cell copy number variations (CNVs). The resulting CNV profiles of established cell lines showed concordance with previously reported data and highlight several gains and losses of cancer-related genes such as FGFR3 and GNAS. The novel sequencing of patient-derived CTC cell lines showed gains in chromosome 8q, 10q and 17q across both CTC cell lines. The pipeline was used to process and isolate single cells from a metastatic pancreatic cancer patient revealing a gain of chromosome 1q and a loss of chromosome 5q. Overall, the Labyrinth-DEPArray pipeline offers a validated workflow combining the benefits of antigen-free CTC isolation with single cell genomic analysis.     

Reconstructing and analyzing periodic human motion from stationary monocular views

We have shown previously that it is possible to accurately reconstruct periodic motions in 3D from a single camera view, using periodicity as a physical constraint from which to perform geometric inference. In this paper we explore the suitability of the reconstruction techniques for real human motion. We examine the degree of periodicity of human gait empirically, and develop algorithmic tools to address some of the challenges arising from this type of motion, including reconstructing motions that deviate from pure periodicity, properly handling the trajectories of multiple points on an articulated body, and proposing a distance function for measuring the difference between two reconstructions. Importantly, we illustrate the usefulness of these techniques by applying them to the tasks of view-invariant activity classification, clinical gait analysis and person identification.     

Alternative responses to dissonance.

50 male and 50 female Ss were placed in an experimental situation in which they found their judgments contradicted by a respected associate of the same sex. Ss were free to resolve the dissonance by conforming to the contrary judgments of the associate, rejecting the associate as one who was less competent than he had been thought to be, underrecalling the disagreements, or, devaluating the importance of the topics about which disagreements had occurred. Female Ss made less use of rejection than did male Ss and were more inclined to tolerate the conflict. Other findings suggest that individuals are inclined to employ the 4 responses as alternative means of reducing dissonance rather than as supplementary means. Finally, correlations relating the MA scale to conformity, underrecall, and tolerance were significantly different for the 2 sexes, suggesting that the effect of anxiety upon Ss' choice of dissonance reducing response depends upon the sex of the Ss. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Model-based control of titer and glycosylation in fed-batch mAb production: Modeling and control system development

Therapeutic monoclonal antibodies (mAbs) are typically manufactured using mammalian cell cultures in fed-batch bioreactors, with increasing emphasis on meeting productivity and product quality attribute targets that depend strongly on such process variables as nutrient feed rates and bioreactor operating conditions. In this article, we identify, categorize, and address the challenges of achieving both productivity and product quality goals simultaneously, by developing a multivariable, model-based control system that can satisfy multiple production objectives in a fed-batch cell culture process. Here, we discuss model development and present theoretical concepts of observability and controllability that are essential to understanding and handling effectively these intrinsic challenges. Subsequently, we evaluate via simulation the performance of the outer-loop model predictive control and demonstrate the overall capability to satisfy complex production objectives in a laboratory scale bioreactor, as a first step toward the ultimate goal of creating an advanced control system for fed-batch mAb manufacturing processes.     

Temperature Distribution in Fluidized Beds of Porous Particles with Liquid Injection

Liquid injection in fluidized beds is used to add reactants or to improve the heat management in the reactor. This injection will increase the complexity of reactor due to the formation of agglomerates. In this work the effect of the injection on the particle temperature distribution in a fluidized bed of porous particles is determined experimentally using particle image velocimetry and infra-red thermography. The main property of the porous particles influencing the distribution is the specific surface area. In addition, the porosity has a large effect on the defluidization of the fluidized bed.     

Regulating Zinc Nucleation Sites and Electric Field Distribution to Achieve High-Performance Zinc Metal Anode via Surface Texturing

Understanding zinc (Zn) deposition behavior and improving Zn stripping and plating reversibility are significant in developing practical aqueous Zn ion batteries (AZIBs). Zn metal is abundant, cost-effective, and intrinsically safe compared with Li. However, their similar inhomogeneous growth regime harms their practicality. This work reports a facile, easily scalable, but effective method to develop a textured Zn with unidirectional scratches on the surface that electrochemically achieves a high accumulated areal capacity of 5530 mAh cm⁻² with homogenized Zn deposition. In symmetric cells, textured Zn presents a stable cycling performance of 1100 hours (vs 250 h of bare Zn) at 0.5 mA cm⁻² for 0.5 mAh cm⁻² and lower nucleation and plating overpotentials of 120.5 and 41.8 mV. In situ optical microscopy and COMSOL simulation disclose that the textured surface topography can 1) homogenize the electron field distribution on the Zn surface and regulate Zn nucleation and growth, and 2) provides physical space to accommodate Zn deposits, prevent the detachment of “dead” Zn, and improve the structural sufficiency of Zn anode. Moreover, differential electrochemical mass spectrometry analysis find that the textured Zn with regulated interfacial electron activity also presents a higher resistance toward hydrogen evolution and other parasitic reactions.