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Full-Text Articles in Physical Sciences and Mathematics
Foam Flotation Enrichment Of Enantiomers, Daniel W. Armstrong, Eve Y. Zhou, Shushi Chen, Kang Le, Yubing Tang
Foam Flotation Enrichment Of Enantiomers, Daniel W. Armstrong, Eve Y. Zhou, Shushi Chen, Kang Le, Yubing Tang
Chemistry Faculty Research & Creative Works
Adsorptive bubble separation methods are known to be useful for processing large amounts of material at a relatively low cost These techniques have been used to enrich components from both heterogeneous and homogeneous solutions. There is a need for economical process-scale enantiomeric separations. Thus far there has been little evidence to support the feasibility of using an adsorptive bubble process to enrich enantiomers. We demonstrate that foam-forming chiral collectors can be used in conjunction with an inexpensive glass device to enantiomerically enrich some pharmaceutically important compounds as well as derivatized and underivatized amino acids. Factors that appeared to affect this …
A Magnetic, Neutron Diffraction, And Mössbauer Spectral Study Of The Nd₂Fe₁₇₋ₓalₓ Solid Solutions, Gary J. Long, Gaya Kanishka Marasinghe, Sanjay R. Mishra, Oran Allan Pringle, Zhongbo Hu, William B. Yelon, D. P. Middleton, K. H. J. Buschow, Fernande Grandjean
A Magnetic, Neutron Diffraction, And Mössbauer Spectral Study Of The Nd₂Fe₁₇₋ₓalₓ Solid Solutions, Gary J. Long, Gaya Kanishka Marasinghe, Sanjay R. Mishra, Oran Allan Pringle, Zhongbo Hu, William B. Yelon, D. P. Middleton, K. H. J. Buschow, Fernande Grandjean
Chemistry Faculty Research & Creative Works
The magnetic properties of a series of Nd2Fe17-xAlx solid solutions, with x equal to 2.04, 4.01, 5.97, 7.94, and 9.06, have been studied by magnetic measurements, neutron diffraction, and Mössbauer spectroscopy. Magnetization studies indicate that the Curie temperature increases from 330 K in Nd2Fe17 to a maximum of ~470 K at an x of 3.5. The compounds crystallize in the Th2Zn17 structure with lattice parameters and unit cell volumes which increase linearly with increasing aluminum content. The neutron diffraction results indicate that aluminum atoms are excluded from the 9d …
Comparative Mössbauer Effect Study Of Several R₂Fe₁₇ And R₂Fe₁₇Nₓ Compounds, Gary J. Long, Sanjay R. Mishra, Oran Allan Pringle, Fernande Grandjean, K. H. Buschow
Comparative Mössbauer Effect Study Of Several R₂Fe₁₇ And R₂Fe₁₇Nₓ Compounds, Gary J. Long, Sanjay R. Mishra, Oran Allan Pringle, Fernande Grandjean, K. H. Buschow
Chemistry Faculty Research & Creative Works
The Mössbauer spectra of Sm2Fe17 and Ho 2Fe17 and their nitrides have been measured between 295 and 85 K and analyzed with a model which is consistent with our earlier work on R2Fe17 and R2Fe17Nx compounds, where R is Pr, Nd, and Th. This model is completely consistent throughout these rare-earth compounds and is in agreement with the crystallographic changes occurring upon nitrogenation and with the prediction of band structure calculations. The dramatic increase in Curie temperature in the nitrides results from the expansion of the crystallographic …
Use Of A Macrocyclic Antibiotic, Rifamycin B, And Indirect Detection For The Resolution Of Racemic Amino Alcohols By Ce, Daniel W. Armstrong, Kumber Rundlett, George L. Reid
Use Of A Macrocyclic Antibiotic, Rifamycin B, And Indirect Detection For The Resolution Of Racemic Amino Alcohols By Ce, Daniel W. Armstrong, Kumber Rundlett, George L. Reid
Chemistry Faculty Research & Creative Works
Ansamycins are a very specific class of macrocyclic antibiotics of which the rifamycins are among the better-known members. Rifamycins bind to and inhibit DNA polymerase. Rifamycin B (the most easily obtained ansamycin) is negatively charged and is shown to associate with and enantioselectively resolve several chiral amino alcohols including terbutaline, isoproterenol, bamethan, metaproterenoi, synephrine, metanephrine, salbutamol, epinephrine, norphenylephrine, ephedrine, ψ-ephedrine, octopamine, norepinephrine, normetanephrine, metoprolol, alprenolol, atenolol, and oxprenolol. A description of the structure and properties of rifamycins, in general, and rifamycin B, in particular, is given. The complexation and chiral recognition of the aforementioned racemic compounds by rifamycin B is …
Macrocyclic Antibiotics As A New Class Of Chiral Selectors For Liquid Chromatography, Daniel W. Armstrong, Yublng Tang, Shushi Chen, Yiwen Zhou, Christina Bagwlll, Jing Ran Chen
Macrocyclic Antibiotics As A New Class Of Chiral Selectors For Liquid Chromatography, Daniel W. Armstrong, Yublng Tang, Shushi Chen, Yiwen Zhou, Christina Bagwlll, Jing Ran Chen
Chemistry Faculty Research & Creative Works
There are a large number of antibiotic macrocycles which include several different structural types. Three representative macrocyclic compounds were covalently linked to silica gel and evaluated by HPLC for their ability to resolve racemic mixtures as well as for their stability and loadability. Over 70 compounds were resolved. In some cases separations were achieved that have not been reported on any other chiral stationary phase (CSP). These stationary phases appear to be multimodal in that they can be used in both the normal-phase and reversed-phase modes. Different compounds are resolved in each mode. There does not appear to be any …
A Mössbauer Effect Study Of The Microscopic Magnetic Properties Of Th₂Fe₁₇ And Its Nitride, Th₂Fe₁₇N₂.₆, Gary J. Long, Oran Allan Pringle, Fernande Grandjean, T. H. Jacobs, K. H. Buschow
A Mössbauer Effect Study Of The Microscopic Magnetic Properties Of Th₂Fe₁₇ And Its Nitride, Th₂Fe₁₇N₂.₆, Gary J. Long, Oran Allan Pringle, Fernande Grandjean, T. H. Jacobs, K. H. Buschow
Chemistry Faculty Research & Creative Works
The Mössbauer spectra of Th2Fe17 and Th2Fe17N2.6 have been measured at various temperatures between 85 and 295 K and analyzed with a model that is based on the Wigner-Seitz cell environment of each iron site, the orientation of the magnetization, and the magnetic moments as determined from either neutron-diffraction measurements or band-structure calculations. Upon nitrogenation of Th2Fe17, the 85 K weighted average isomer shift increases from 0.037 to 0.156 mm/s and further the isomer shifts of the four crystallographically distinct sites increase in agreement with the increase observed …
A Prospective Community-Based Study Of Stroke In Warsaw, Poland, Anna Czlonkowska, Danuta Ryglewicz, Thomas Weissbein, Maria Baranska-Gieruszczak, Daniel B. Hier
A Prospective Community-Based Study Of Stroke In Warsaw, Poland, Anna Czlonkowska, Danuta Ryglewicz, Thomas Weissbein, Maria Baranska-Gieruszczak, Daniel B. Hier
Chemistry Faculty Research & Creative Works
Background and Purpose Poland is a Country with High Morbidity and Mortality Rates from Cardiovascular Diseases. No Recent Studies Have Evaluated the Contribution of Cerebrovascular Diseases to This Morbidity and Mortality. Our Aim Was to Accurately Determine Stroke Incidence Rates in Warsaw, Poland. Methods a 2-Year Prospective and Population-Based Stroke Registry Was Maintained for Health Care Units 2 and 3 in Warsaw, Poland (Population, 182 285). Case Subjects Were Ascertained by Surveying Hospital Admissions, Outpatient Visits, and Death Certificates. Results during the 2 Years of the Study (1991 to 1992), 633 Cases of First-Event Strokes Were Registered, 462 of Which …
Gender And Aphasia In The Stroke Data Bank, Daniel B. Hier, William B. Yoon, J. P. Mohr, Thomas R. Price, Philip A. Wolf
Gender And Aphasia In The Stroke Data Bank, Daniel B. Hier, William B. Yoon, J. P. Mohr, Thomas R. Price, Philip A. Wolf
Chemistry Faculty Research & Creative Works
Aphasia Was Present in 19.4% of the Men and 22.5% of the Women in the Stroke Data Bank. There Were No Gender Differences in Aphasia Incidence among the Intracerebral Hemorrhages. Aphasia Was More Frequent among Women with Infarcts (37.0%) Than Men (28.3%). When Stroke Mechanism Was Controlled For, There Was an Excess of Aphasia among the Women with Stroke Due to Cardiac Embolism. When Stroke Site Was Controlled For, There Were No Gender Differences in Aphasia Frequency. Wernicke′s, Global, and Anomic Aphasias Were More Common in Women Than Men; Broca′s Aphasia Was Somewhat More Common in Men. Although There Were …
Distribution Of Sedimentary Phosphorus In Gulf Of Mexico Estuaries, Weng Huanxin, Bob J. Presley, Daniel W. Armstrong
Distribution Of Sedimentary Phosphorus In Gulf Of Mexico Estuaries, Weng Huanxin, Bob J. Presley, Daniel W. Armstrong
Chemistry Faculty Research & Creative Works
Sediment samples were collected from all the major bays and estuaries along the US Gulf of Mexico Coastline in 1986-1988 by the NOAA NS & T Program (NOAA (1989), The National Status and Trends Program for marine environmental quality; NOAA/OMA, Rockville, MD, USA). These have been analyzed for total phosphorus as well as leachable Al-P, Ca-P and Fe-P. Total phosphorus concentration ranges from 1·8 to 45·9 μmol/g and averages 11·3 μmol/g. Higher values were found in Louisiana estuaries than in those in Texas but the highest values occur in the phosphate rock mining region of southern Florida. Ca-P is the …