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Search Results: 1 - 10 of 86986 matches for " Justin W. Gorski "
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XRF Standardless Comparison of Mining Head and Tail Grades to Screen and Display Ore Processing Recoveries  [PDF]
Nicholas E. Pingitore Jr, Juan W. Clague, Daniel Gorski
American Journal of Analytical Chemistry (AJAC) , 2016, DOI: 10.4236/ajac.2016.711070
Abstract: Separation of target elements or minerals from their host rock or ore is essential to successful mining operation. The inevitable loss of a portion of the desired material that accompanies each step in the extraction process must be documented to develop the operational protocol. Superposition of the characteristic X-ray fluorescence spectra of head (crushed rock ore particles, pre-processing) and tail (post-processing particles) samples provides a direct visual comparison of relative peak sizes, and thereby the relative concentrations, of elements of interest. If the head and tail peaks are identical, none of the element was recovered in the extraction process. At the other extreme if the tail peak “flat lines”, i.e., there is no peak, there was 100% recovery of that element. Standardless visual comparison is valid if the same mass of identical starting material is incorporated into the head and tail sample analysis pucks, and XRF analytical conditions are identical. The considerable time and expense of acquiring and calibrating the standards associated with XRF analysis of 75 or more elements are avoided, a significant advantage during initial broad screening of an experimental extraction procedure. Full quantitation by XRF or an alternate technique can proceed at a later project stage, if desired. The approach retains and presents all features of the original data, thus eliminating questions about data quality, standards and their calibration, and data manipulation in processing from raw counts to concentrations in printout tables. This form of display is ideal for both the mining professional and such less technical groups as corporate staff, investors, regulators, and the public. Examples presented herein are for heap leaching; the protocol can be applied as well to any of the other traditional ore processing and beneficiation procedures, e.g., gravity concentration, magnetic and electrical separation, froth flotation, and ore sorting.
Remarkably Consistent Rare Earth Element Grades at Round Top Yttrofluorite Deposit  [PDF]
Nicholas E. Pingitore Jr., Juan W. Clague, Daniel Gorski
Advances in Materials Physics and Chemistry (AMPC) , 2018, DOI: 10.4236/ampc.2018.81001
Abstract: The peraluminous rhyolite that forms Round Top Mountain (approximately 375 m high × nearly 2 km in diameter), near Sierra Blanca, Hudspeth County, west Texas, USA, is enriched in yttrium and heavy rare earth elements (YHREEs), as well as Li, Be, U, Th, Sn, F, Rb, Cs, Nb, and Ta. Texas Mineral Resources Corp. (USA) proposes to release the YHREEs from their unique yttrofluorite host via heap leaching with dilute sulfuric acid. The inexpensive process also releases portions of valuable byproduct Be, Li, and U from accessory minerals amid the insoluble feldspars and quartz that comprise 90% - 95% of the surface-exposed rhyolite mountain. The objective of this study is to determine the consistency of mineralization grade, an important consideration in mine planning and preliminary economic analysis. The method is to plot elemental analyses of Y, Dy, Ho, Tm, Yb, Ce, Pr, Nd, Eu, Gd, Tb, U, and Nb from more than 1400 reverse circulation cuttings taken from 64 exploration drill holes against sample depth. The result of inspection of the plots reveals a remarkably homogeneous distribution of minor and trace elements throughout the sampled portion of the massive, 1.6-billion-tonne laccolith. The plots drive the conclusion that Round Top mine feedstock should remain constant for the life of the mine (multiple decades). Thus mining mechanics could be optimized at the start of operations and not require expensive later changes. The physical and chemical design of the heap leach and recovery and purification of target elements from pregnant leach solution also could be perfected during early development.
Complement Inhibition Promotes Endogenous Neurogenesis and Sustained Anti-Inflammatory Neuroprotection following Reperfused Stroke
Andrew F. Ducruet, Brad E. Zacharia, Sergey A. Sosunov, Paul R. Gigante, Mason L. Yeh, Justin W. Gorski, Marc L. Otten, Richard Y. Hwang, Peter A. DeRosa, Zachary L. Hickman, Paulina Sergot, E. Sander Connolly
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0038664
Abstract: Background and Purpose The restoration of blood-flow following cerebral ischemia incites a series of deleterious cascades that exacerbate neuronal injury. Pharmacologic inhibition of the C3a-receptor ameliorates cerebral injury by attenuating post-ischemic inflammation. Recent reports also implicate C3a in the modulation of tissue repair, suggesting that complement may influence both injury and recovery at later post-ischemic time-points. Methods To evaluate the effect of C3a-receptor antagonism on post-ischemic neurogenesis and neurological outcome in the subacute period of stroke, transient focal cerebral ischemia was induced in adult male C57BL/6 mice treated with multiple regimens of a C3a receptor antagonist (C3aRA). Results Low-dose C3aRA administration during the acute phase of stroke promotes neuroblast proliferation in the subventricular zone at 7 days. Additionally, the C3a receptor is expressed on T-lymphocytes within the ischemic territory at 7 days, and this cellular infiltrate is abrogated by C3aRA administration. Finally, C3aRA treatment confers robust histologic and functional neuroprotection at this delayed time-point. Conclusions Targeted complement inhibition through low-dose antagonism of the C3a receptor promotes post-ischemic neuroblast proliferation in the SVZ. Furthermore, C3aRA administration suppresses T-lymphocyte infiltration and improves delayed functional and histologic outcome following reperfused stroke. Post-ischemic complement activation may be pharmacologically manipulated to yield an effective therapy for stroke.
Determination of surface charge density of α-alumina by Acid - base titration
Justin W. Ntalikwa
Bulletin of the Chemical Society of Ethiopia , 2007,
Abstract: The surface charge density (so) of colloidal alpha alumina suspended in various 1:1 electrolytes was measured using acid-base titration. An autotitrator capable of dispensing accurately 25 ± 0.1 mL of titrant was used. The pH and temperature in the titration cell were monitored using single junction electrodes and platinum resistance thermometers, respectively. A constant supply of nitrogen gas in the cell was used to maintain inert conditions. The whole set up was interfaced with a computer for easy data acquisition. It was observed that the material exhibits a point of zero charge (PZC), this occurred at pH of 7.8 ± 0.1, 7.6 ± 0.2, 8.5 ± 0.1, 8.3 ± 0.1 for NaCl, NaNO3, CsCl and CsNO3 systems, respectively. It was also observed that below PZC, so increases with increase in electrolyte concentration (Co) whereas above PZC, so decreases with increase in Co. It was concluded that so of this material is a function of pH and Co and that its polarity can be varied through zero by varying these parameters. KEY WORDS: Alumina, Surface charge density, Acid-base titration, Point of zero charge Bull. Chem. Soc. Ethiop. 2007, 21(1), 117-128.
Determination of surface charge density of α-alumina by acid-base titration
Justin W. Ntalikwa
Bulletin of the Chemical Society of Ethiopia , 2007,
Abstract: The surface charge density (σo) of colloidal alpha alumina suspended in various 1:1 electrolytes was measured using acid-base titration. An autotitrator capable of dispensing accurately 25 plus or minus 0.1 μL of titrant was used. The pH and temperature in the titration cell were monitored using single junction electrodes and platinum resistance thermometers, respectively. A constant supply of nitrogen gas in the cell was used to maintain inert conditions. The whole set up was interfaced with a computer for easy data acquisition. It was observed that the material exhibits a point of zero charge (PZC), this occurred at pH of 7.8 plus or minus 0.1, 7.6 plus or minus 0.2, 8.5 plus or minus 0.1, 8.3 plus or minus 0.1 for NaCl, NaNO3, CsCl and CsNO3 systems, respectively. It was also observed that below PZC, σo increases with increase in electrolyte concentration (Co) whereas above PZC, σo decreases with increase in Co. It was concluded that σo of this material is a function of pH and Co and that its polarity can be varied through zero by varying these parameters.
On the Rank of Multi-graded Differential Modules
Justin W. DeVries
Mathematics , 2010,
Abstract: A \mathbb{Z}^d-graded differential R-module is a \mathbb{Z}^d-graded R-module equipped with an endomorphism, \delta, that squares to zero. For R=k[x_1,...,x_d], this paper establishes a lower bound on the rank of such a differential module when the underlying R-module is free. We define the Betti number of a differential module and use it to show that when the homology H(D)=ker(\delta)/im(\delta) of D is non-zero and finite dimensional over k then there is an inequality rank_R D >= 2^d.
HLA-DM Mediates Epitope Selection by a “Compare-Exchange” Mechanism when a Potential Peptide Pool Is Available
Andrea Ferrante, Matthew W. Anderson, Candice S. Klug, Jack Gorski
PLOS ONE , 2008, DOI: 10.1371/journal.pone.0003722
Abstract: Background HLA-DM (DM) mediates exchange of peptides bound to MHC class II (MHCII) during the epitope selection process. Although DM has been shown to have two activities, peptide release and MHC class II refolding, a clear characterization of the mechanism by which DM facilitates peptide exchange has remained elusive. Methodology/Principal Findings We have previously demonstrated that peptide binding to and dissociation from MHCII in the absence of DM are cooperative processes, likely related to conformational changes in the peptide-MHCII complex. Here we show that DM promotes peptide release by a non-cooperative process, whereas it enhances cooperative folding of the exchange peptide. Through electron paramagnetic resonance (EPR) and fluorescence polarization (FP) we show that DM releases prebound peptide very poorly in the absence of a candidate peptide for the exchange process. The affinity and concentration of the candidate peptide are also important for the release of the prebound peptide. Increased fluorescence energy transfer between the prebound and exchange peptides in the presence of DM is evidence for a tetramolecular complex which resolves in favor of the peptide that has superior folding properties. Conclusion/Significance This study shows that both the peptide releasing activity on loaded MHCII and the facilitating of MHCII binding by a candidate exchange peptide are integral to DM mediated epitope selection. The exchange process is initiated only in the presence of candidate peptides, avoiding possible release of a prebound peptide and loss of a potential epitope. In a tetramolecular transitional complex, the candidate peptides are checked for their ability to replace the pre-bound peptide with a geometry that allows the rebinding of the original peptide. Thus, DM promotes a “compare-exchange” sorting algorithm on an available peptide pool. Such a “third party”-mediated mechanism may be generally applicable for diverse ligand recognition in other biological systems.
Patient preferences and factors related to the pre-procedure process at a large, urban county hospital  [PDF]
Lukejohn W. Day, Michelle Nazareth, Justin L. Sewell
Open Journal of Gastroenterology (OJGas) , 2013, DOI: 10.4236/ojgas.2013.31002
Abstract:

Background: Evaluation of the pre-procedural process prior to endoscopic procedures has never been conducted. Methods: Prospective cross-sectional, multi-language survey was administered to outpatients undergoing endoscopy at a large, diverse county hospital that examined patients’ pre-procedural preferences. Multivariate logistic regression was used to assess the relationship between patient preferences and several patient-related variables. Results: 128/156 outpatients completed the survey. The majority of respondents were female (53.1%), did not speak English (61.7%), were of Asian (39.1%) or Hispanic (29.7%) racial background, and had a mean age of 56.1 ± 15.7 years. Most patients underwent colonoscopy (48.4%) with 90.6% of patients knowing the indication for their procedure. While waiting for their endoscopic procedure, 42.2% of patients preferred waiting in a gurney while 28.1% preferred to wait in a chair. In terms of being comfortable wearing a hos- pital gown and sitting in a chair or gurney in the pre-procedure area, mean patient anxiety scores were 5.2 ± 3.3 and 6.1 ± 3.2, respectively (scale of 1 - 10). Race was associated with several pre-procedural patient preferences; Hispanics were less comfortable than Asians wearing a hospital gown while sitting in a chair with other patients prior to their procedure (OR = 0.3, CI 0.1 - 1.0) while Whites and African-Americans were less likely than Asians to prefer sitting in a chair as compared to a gurney before their procedure (OR = 0.09, CI 0.008 - 0.9 and OR = 0.07, CI 0.007 - 0.8, respectively). Patients who had undergone a prior endoscopic procedure were less comfortable wearing a hospital gown and sitting in a chair (OR = 0.3, CI 0.1 - 0.7) or gurney (OR = 0.4, CI 0.2 - 1.0) in the pre-procedure area. Conclusion: A patient’s race and having had a prior endoscopic procedure were the most powerful predictors on pre-procedure patient preferences while sex, type of endoscopic procedure and patient knowledge of the indication for their procedure were not. Our study highlights the importance of patient preferences and factors involved in the pre procedure process at a large, diverse county hospital.

A Multi-Stage CUDA Kernel for Floyd-Warshall
Ben Lund,Justin W Smith
Computer Science , 2010,
Abstract: We present a new implementation of the Floyd-Warshall All-Pairs Shortest Paths algorithm on CUDA. Our algorithm runs approximately 5 times faster than the previously best reported algorithm. In order to achieve this speedup, we applied a new technique to reduce usage of on-chip shared memory and allow the CUDA scheduler to more effectively hide instruction latency.
Selective Enrichment Media Bias the Types of Salmonella enterica Strains Isolated from Mixed Strain Cultures and Complex Enrichment Broths
Lisa Gorski
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0034722
Abstract: For foodborne outbreak investigations it can be difficult to isolate the relevant strain from food and/or environmental sources. If the sample is contaminated by more than one strain of the pathogen the relevant strain might be missed. In this study mixed cultures of Salmonella enterica were grown in one set of standard enrichment media to see if culture bias patterns emerged. Nineteen strains representing four serogroups and ten serotypes were compared in four-strain mixtures in Salmonella-only and in cattle fecal culture enrichment backgrounds using Salmonella enrichment media. One or more strain(s) emerged as dominant in each mixture. No serotype was most fit, but strains of serogroups C2 and E were more likely to dominate enrichment culture mixtures than strains of serogroups B or C1. Different versions of Rappaport-Vassiliadis (RV) medium gave different patterns of strain dominance in both Salmonella-only and fecal enrichment culture backgrounds. The fittest strains belonged to serogroups C1, C2, and E, and included strains of S. Infantis, S. Thompson S. Newport, S. 6,8:d:-, and S. Give. Strains of serogroup B, which included serotypes often seen in outbreaks such as S. Typhimurium, S. Saintpaul, and S. Schwarzengrund were less likely to emerge as dominant strains in the mixtures when using standard RV as part of the enrichment. Using a more nutrient-rich version of RV as part of the protocol led to a different pattern of strains emerging, however some were still present in very low numbers in the resulting population. These results indicate that outbreak investigations of food and/or other environmental samples should include multiple enrichment protocols to ensure isolation of target strains of Salmonella.
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