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Search Results: 1 - 10 of 222210 matches for " Philip L. Smith "
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Regioselective Synthesis and Biological Evaluation of 1-Hydroxyl Modified Ailanthinone Derivatives as Antimalarials  [PDF]
Mahendra D. Chordia, William F. McCalmont, Kirsten S. Smith, Philip L. Smith
Open Journal of Synthesis Theory and Applications (OJSTA) , 2013, DOI: 10.4236/ojsta.2013.24012

The triterpene quassinoid ailanthinone is a structurally intricate natural product possessing highly potent antimalarial activity against multidrug resistance plasmodium parasites. Although the mechanism of action of ailanthinone is not completely understood, it is presumed to disrupt regular ribosomal functions by inhibiting parasite protein synthesis. Natural scarcity and low solubility of many quassinoids have impeded their development as potential clinical candidates, but exquisite potency of ailanthinone against Plasmodium remains compelling in the global fight against malaria. Herein, we report the highly selective synthesis of 1-hydroxyl derivatives of ailanthinone, including ester, carbonate, carbamate and sulfonate derivatives. The key feature of the synthesis is a one-step regioselective modification of the 1-hydroxyl group in favor of two other hydroxyl groups at C12 and C13. Derivatives were obtained via direct reaction with acyl/sulfonyl chlorides in the presence of a tertiary amine base without any protection-deprotection. In vitro antimalarial evaluations of these derivatives were compared with chloroquine and mefloquine against the Plasmodium falciparum clones, D6, W2, and TM91C235. The results demonstrate that modification of the 1-hydroxyl group is achievable, and the antimalarial activity of these derivatives relative to the parent product is significantly retained, thus paving the way for synthesis of derivatives with improved biological availability and/or increased potency.

The Effect of Catena Position on Greenhouse Gas Emissions from Dambo Located Termite (Odontotermes transvaalensis) Mounds from Central Zimbabwe  [PDF]
George Nyamadzawo, Jephita Gotosa, Justice Muvengwi, Menas Wuta, Justice Nyamangara, Philip Nyamugafata, Jeff L. Smith
Atmospheric and Climate Sciences (ACS) , 2012, DOI: 10.4236/acs.2012.24044
Abstract: Methane (CH4), carbon dioxide (CO2) and nitrous oxide (N2)O) are greenhouse gases (GHGs) which cause global warming. Natural sources of GHGs include wetlands and termites. Previous studies have quantified GHG emissions from upland termites and no study has reported GHG emissions from seasonal wetlands (dambo) located termite mounds. The objective of this study was to evaluate the effect of dambo catena position on termite mound distribution and GHG emissions. It was hypothesized that mound density and GHG emissions from Odontotermes transvaalensis mounds, vary with catena position. The evaluated catena positions were margin, mid-slope, lower slope and bottom. Mound density was significantly lower in the bottom when compared to the other catena positions. The mean GHG fluxes were 88 μg m2 hr-1, 0.78 mg m2 hr-1 and 1361 mg m2 hr-1 for N2) O, CH4 and CO2 respectively. Fluxes varied with catena position and were 0.48, 0.72, 1.35 and 0.79 mg m-2 hr-1 for CH4 , and 1173.7, 1440.7, 1798.7 and 922.8 mg m-2 hr-1 for CO2 in the margin, mid-slope, lower slope and the bottom catena position respectively. For N2) O, there were no significant differences between catena positions. It was concluded that dambo located Odontotermes transvaalensis termite mounds are an important source of GHGs, and emissions varied with catena position for CO2 and CH4.
Single Top from Technipion Production
Philip Baringer,Pankaj Jain,Douglas W. Mckay,Lesley L. Smith
Physics , 1997, DOI: 10.1103/PhysRevD.56.2914
Abstract: We investigate the contribution of technicolor mechanisms to the production of single top quarks at hadron colliders. Technipions with mass larger than the top mass will decay predominantly to a top quark plus a bottom antiquark. We investigate two promising sub-processes: technipion plus W-boson via gluon-gluon fusion and technipion plus quark production via quark gluon interaction. The decay chain of technipion to top plus bottom quarks and then top to W plus bottom yields final states for the two subprocesses with, respectively, two W's and two bottom quarks and one W, two bottom quarks and a light quark. We calculate the total cross sections and the $p_{T}$ distributions for these technipion production mechanisms at Tevatron and LHC energies for a range of technipion masses, starting at 200 GeV. We study the backgrounds to our processes and the kinematic cuts that enhance the signal to background ratio and we report event rate estimates for the upgraded Tevatron and the LHC. Only the LHC has the potential to observe these processes.
The Relationship between Diver Experience Levels and Perceptions of Attractiveness of Artificial Reefs - Examination of a Potential Management Tool
Anne E. Kirkbride-Smith, Philip M. Wheeler, Magnus L. Johnson
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0068899
Abstract: Artificial reefs are increasingly used worldwide as a method for managing recreational diving since they have the potential to satisfy both conservation goals and economic interests. In order to help maximize their utility, further information is needed to drive the design of stimulating resources for scuba divers. We used a questionnaire survey to explore divers’ perceptions of artificial reefs in Barbados. In addition, we examined reef resource substitution behaviour among scuba divers. Divers expressed a clear preference for large shipwrecks or sunken vessels that provided a themed diving experience. Motives for diving on artificial reefs were varied, but were dominated by the chance of viewing concentrated marine life, increased photographic opportunities, and the guarantee of a ‘good dive’. Satisfaction with artificial reef diving was high amongst novices and declined with increasing experience. Experienced divers had an overwhelming preference for natural reefs. As a management strategy, our results emphasize the capacity of well designed artificial reefs to contribute towards the management of coral reef diving sites and highlight a number of important areas for future research. Suggested work should validate the present findings in different marine tourism settings and ascertain support of artificial reefs in relationship to level of diver specialization.
Determining Airborne Concentrations of Spatial Repellent Chemicals in Mosquito Behavior Assay Systems
Nicholas J. Martin, Philip A. Smith, Nicole L. Achee, Gerald T. DeLong
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0071884
Abstract: Background Mosquito behavior assays have been used to evaluate the efficacy of vector control interventions to include spatial repellents (SR). Current analytical methods are not optimized to determine short duration concentrations of SR active ingredients (AI) in air spaces during entomological evaluations. The aim of this study was to expand on our previous research to further validate a novel air sampling method to detect and quantitate airborne concentrations of a SR under laboratory and field conditions. Methodology/Principal Findings A thermal desorption (TD) gas chromatography-mass spectrometry (GC-MS) method was used to determine the amount of dichlorodiphenyltrichloroethane (DDT) in samples of air. During laboratory experiments, 1 L volumes of air were collected over 10 min intervals from a three-chamber mosquito behavior assay system. Significantly higher levels of airborne DDT were measured in the chamber containing textiles treated with DDT compared to chambers free of AI. In the field, 57 samples of air were collected from experimental huts with and without DDT for onsite analysis. Airborne DDT was detected in samples collected from treated huts. The mean DDT air concentrations in these two huts over a period of four days with variable ambient temperature were 0.74 μg/m3 (n = 17; SD = 0.45) and 1.42 μg/m3 (n = 30; SD = 0.96). Conclusions/Significance The results from laboratory experiments confirmed that significantly different DDT exposure conditions existed in the three-chamber system establishing a chemical gradient to evaluate mosquito deterrency. The TD GC-MS method addresses a need to measure short-term (<1 h) SR concentrations in small volume (<100 L) samples of air and should be considered for standard evaluation of airborne AI levels in mosquito behavior assay systems. Future studies include the use of TD GC-MS to measure other semi-volatile vector control compounds.
Impact of Chlorine Dioxide Gas Sterilization on Nosocomial Organism Viability in a Hospital Room
John J. Lowe,Shawn G. Gibbs,Peter C. Iwen,Philip W. Smith,Angela L. Hewlett
International Journal of Environmental Research and Public Health , 2013, DOI: 10.3390/ijerph10062596
Abstract: To evaluate the ability of ClO 2 to decontaminate pathogens known to cause healthcare-associated infections in a hospital room strains of Acinetobacter baumannii, Escherichia coli, Enterococcus faecalis, Mycobacterium smegmatis, and Staphylococcus aureus were spot placed in duplicate pairs at 10 sites throughout a hospital room and then exposed to ClO 2 gas. Organisms were collected and evaluated for reduction in colony forming units following gas exposure. Six sterilization cycles with varied gas concentrations, exposure limits, and relative humidity levels were conducted. Reductions in viable organisms achieved ranged from 7 to 10-log reductions. Two sterilization cycles failed to produce complete inactivation of organisms placed in a bathroom with the door closed. Reductions of organisms in the bathroom ranged from 6-log to 10-log reductions. Gas leakage between hospital floors did not occur; however, some minor gas leakage from the door of hospital room was measured which was subsequently sealed to prevent further leakage. Novel technologies for disinfection of hospital rooms require validation and safety testing in clinical environments. Gaseous ClO 2 is effective for sterilizing environmental contamination in a hospital room. Concentrations of ClO 2 up to 385 ppm were safely maintained in a hospital room with enhanced environmental controls.
Two distinct electronic sites in the Cu-O plane of the (La,Sr)CuO(4) pseudogap state
Robert X. Smith,Philip L. Kuhns,Arneil P. Reyes,Gregory S. Boebinger
Physics , 2011,
Abstract: The pseudogap state is widely regarded as a precursor to high-temperature superconductivity yet remains poorly understood. Using high field (30 T) NMR, we report two electronically distinct oxygen sites within the copper-oxygen (Cu-O) planes of an underdoped cuprate in the pseudogap state. At temperatures well above the bulk superconducting transition, roughly 25% of the oxygen sites evidence superconducting pair formation, the remaining evidence antiferromagnetic ordering on the nearest neighbor Cu sites. Any superconducting fluctuations are slower than the microsecond timescales of the NMR probe, a confirmation that the (nearly) static bimodality of electronic sites in the Cu-O plane - first reported using scanning tunneling microscopy on surfaces - extends throughout the bulk pseudogap state.
Complete Primate Skeleton from the Middle Eocene of Messel in Germany: Morphology and Paleobiology
Jens L. Franzen, Philip D. Gingerich, J?rg Habersetzer, J?rn H. Hurum, Wighart von Koenigswald, B. Holly Smith
PLOS ONE , 2009, DOI: 10.1371/journal.pone.0005723
Abstract: Background The best European locality for complete Eocene mammal skeletons is Grube Messel, near Darmstadt, Germany. Although the site was surrounded by a para-tropical rain forest in the Eocene, primates are remarkably rare there, and only eight fragmentary specimens were known until now. Messel has now yielded a full primate skeleton. The specimen has an unusual history: it was privately collected and sold in two parts, with only the lesser part previously known. The second part, which has just come to light, shows the skeleton to be the most complete primate known in the fossil record. Methodology/Principal Findings We describe the morphology and investigate the paleobiology of the skeleton. The specimen is described as Darwinius masillae n.gen. n.sp. belonging to the Cercamoniinae. Because the skeleton is lightly crushed and bones cannot be handled individually, imaging studies are of particular importance. Skull radiography shows a host of teeth developing within the juvenile face. Investigation of growth and proportion suggest that the individual was a weaned and independent-feeding female that died in her first year of life, and might have attained a body weight of 650–900 g had she lived to adulthood. She was an agile, nail-bearing, generalized arboreal quadruped living above the floor of the Messel rain forest. Conclusions/Significance Darwinius masillae represents the most complete fossil primate ever found, including both skeleton, soft body outline and contents of the digestive tract. Study of all these features allows a fairly complete reconstruction of life history, locomotion, and diet. Any future study of Eocene-Oligocene primates should benefit from information preserved in the Darwinius holotype. Of particular importance to phylogenetic studies, the absence of a toilet claw and a toothcomb demonstrates that Darwinius masillae is not simply a fossil lemur, but part of a larger group of primates, Adapoidea, representative of the early haplorhine diversification.
Prevalence of sacral dysmorphia in a prospective trauma population: Implications for a "safe" surgical corridor for sacro-iliac screw placement
Erik A Hasenboehler, Philip F Stahel, Allison Williams, Wade R Smith, Justin T Newman, David L Symonds, Steven J Morgan
Patient Safety in Surgery , 2011, DOI: 10.1186/1754-9493-5-8
Abstract: Prospective observational cohort study on a consecutive series of 344 skeletally mature trauma patients of both genders enrolled between January 1, 2007, to September 30, 2007, at a single academic level 1 trauma center. Inclusion criteria included a pelvic CT scan as part of the initial diagnostic trauma work-up. The prevalence of sacral dysmorphia was determined by plain radiographic pelvic films and CT scan analysis. The anatomy of sacral corridors was analyzed on 3 mm reconstruction sections derived from multislice CT scan, in the axial, coronal, and sagittal plane. "Safe" potential surgical corridors at S1 and S2 were calculated based on these measurements.Radiographic evidence of sacral dysmorphia was detected in 49 patients (14.5%). The prevalence of sacral dysmorphia was not significantly different between male and female patients (12.2% vs. 19.2%; P = 0.069). In contrast, significant gender-related differences were detected with regard to radiographic analysis of surgical corridors for SI-screw placement, with female trauma patients (n = 99) having significantly narrower corridors at S1 and S2 in all evaluated planes (axial, coronal, sagittal), compared to male counterparts (n = 245; P < 0.01). In addition, the mean S2 body height was higher in dysmorphic compared to normal sacra, albeit without statistical significance (P = 0.06), implying S2 as a safe surgical corridor of choice in patients with sacral dysmorphia.These findings emphasize a high prevalence of sacral dysmorphia in a representative trauma population and imply a higher risk of SI-screw misplacement in female patients. Preoperative planning for percutaneous SI-screw fixation for unstable pelvic and sacral fractures must include a detailed CT scan analysis to determine the safety of surgical corridors.Percutaneous sacro-iliac (SI) screw fixation represents an established standard and widely used technique in the management of unstable posterior pelvic ring injuries and sacral fractures [1-4]. T
Philip R. Smith
Essays in Economic & Business History , 2000,
Abstract: Obituary of Jack Blicksilver (1926-1999).
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