The compound dimethyl sulfide (DMS) links terrestrial and oceanic sulfur with the atmosphere because of its volatility. Atmospheric DMS is responsible for cloud formation and radiation backscattering and has been implicated in climate control mitigation. The enzyme DMS -monooxygenase degrades DMS and has been classified as a two-component FMNH-dependent monooxygenase.
View Article and Find Full Text PDFRev Sci Instrum
November 2015
In situ characterization of micro- and nanoscale defects in polycrystalline thin-film materials is required to elucidate the physics governing defect formation and evolution during photovoltaic device fabrication and operation. X-ray fluorescence spectromicroscopy is particularly well-suited to study defects in compound semiconductors, as it has a large information depth appropriate to study thick and complex materials, is sensitive to trace amounts of atomic species, and provides quantitative elemental information, non-destructively. Current in situ methods using this technique typically require extensive sample preparation.
View Article and Find Full Text PDFThis paper presents the design and characterization of a three-axis thermomechanical actuator-based endoscopic scanner for obtaining two-photon images. The scanner consisted of two sub-systems: 1) an optical system (prism, gradient index lens, and optical fiber) that was used to deliver and collect light during imaging and 2) a small-scale silicon electromechanical scanner that could raster scan the focal point of the optics through a specimen. The scanner can be housed within a 7 mm Ø endoscope port and can scan at the speed of 3 kHz × 100 Hz × 30 Hz along three axes throughout a 125 × 125 × 100 m volume.
View Article and Find Full Text PDFIn the initial steps of their metabolic pathway, methanotrophic bacteria oxidize methane to methanol with methane monooxygenases (MMOs) and methanol to formaldehyde with methanol dehydrogenases (MDHs). Several lines of evidence suggest that the membrane-bound or particulate MMO (pMMO) and MDH interact to form a metabolic supercomplex. To further investigate the possible existence of such a supercomplex, native MDH from Methylococcus capsulatus (Bath) has been purified and characterized by size exclusion chromatography with multi-angle light scattering and X-ray crystallography.
View Article and Find Full Text PDFParticulate methane monooxygenase (pMMO) catalyzes the oxidation of methane to methanol in methanotrophic bacteria. As a copper-containing enzyme, pMMO has been investigated extensively by electron paramagnetic resonance (EPR) spectroscopy, but the presence of multiple copper centers has precluded correlation of EPR signals with the crystallographically identified monocopper and dicopper centers. A soluble recombinant fragment of the pmoB subunit of pMMO, spmoB, like pMMO itself, contains two distinct copper centers and exhibits methane oxidation activity.
View Article and Find Full Text PDFThis paper presents the design and fabrication of a multi-axis microelectromechanical system (MEMS) force sensor with integrated carbon nanotube (CNT)-based piezoresistive sensors. Through the use of proper CNT selection and sensor fabrication techniques, the performance of the CNT-based MEMS force sensor was increased by approximately two orders of magnitude as compared to current CNT-based sensor systems. The range and resolution of the force sensor were determined as 84 μN and 5.
View Article and Find Full Text PDFCrit Rev Biochem Mol Biol
April 2013
Particulate methane monooxygenase (pMMO) is an integral membrane metalloenzyme that oxidizes methane to methanol in methanotrophic bacteria, organisms that live on methane gas as their sole carbon source. Understanding pMMO function has important implications for bioremediation applications and for the development of new, environmentally friendly catalysts for the direct conversion of methane to methanol. Crystal structures of pMMOs from three different methanotrophs reveal a trimeric architecture, consisting of three copies each of the pmoB, pmoA, and pmoC subunits.
View Article and Find Full Text PDFParticulate methane monooxygenase (pMMO) is an integral membrane metalloenzyme that converts methane to methanol in methanotrophic bacteria. The enzyme consists of three subunits, pmoB, pmoA, and pmoC, organized in an α(3)β(3)γ(3) trimer. Studies of intact pMMO and a recombinant soluble fragment of the pmoB subunit (denoted as spmoB) indicate that the active site is located within the soluble region of pmoB at the site of a crystallographically modeled dicopper center.
View Article and Find Full Text PDFThis paper focuses on the design and implementation of a percutaneous catheter-based device to provide physicians with an externally controlled tool capable of manipulating and cutting specific chordae tendinae within the hear to alleviate problems associated with some forms of mitral valve regurgitationt. In the United States alone, approximately 500,000 people develop ischemic or functional MR per year, and the chordae tendinae cutting procedure and device are needed because many patients do not have the required level of health necessary to survive open-heart surgery. A deterministic design process was used to generate several design concepts and then evaluate and compare each concept based on a set of functional requirements.
View Article and Find Full Text PDFProlyl 4-hydroxylases (P4H) catalyze the post-translational hydroxylation of proline residues and play a role in collagen production, hypoxia response, and cell wall development. P4Hs belong to the group of Fe(II)/alphaKG oxygenases and require Fe(II), alpha-ketoglutarate (alphaKG), and O(2) for activity. We report the 1.
View Article and Find Full Text PDFIsolated renal infections with fungal organisms of the class Zygomycetes are rare, but these infections are most frequently seen in patients who are immunocompromised. We report the case of a 45-year-old African American man who presented with symptoms of right-sided pyelonephritis, including fever, dysuria, and flank pain. The patient's history was significant only for sickle cell trait, and no evidence of immunosuppression was identified.
View Article and Find Full Text PDFThe biogenesis of the topaquinone (TPQ) cofactor of copper amine oxidase (CAO) is self-catalyzed and requires copper and molecular oxygen. A dopaquinone intermediate has been proposed to undergo 1,4-addition of a copper-associated water molecule to form the reduced form of TPQ (TPQ(red)), followed by facile oxidation by O(2) to yield the mature TPQ (TPQ(ox)). In this study, we have incorporated a lysine residue in the active site of Arthrobacter globiformis CAO (AGAO) by site-directed mutagenesis to produce D298K-AGAO.
View Article and Find Full Text PDFA novel, highly accurate, all electronic technique for phase locking arrays of optical fibers is demonstrated. We report the first demonstration of the only electronic phase locking technique that doesn't require a reference beam. The measured phase error is lambda/20.
View Article and Find Full Text PDFA suitable ergometer that is generally favored for estimating maximal oxygen consumption (VO2 max) under field conditions or in environments where testing equipment is limited is the step test. Recently a mathematical model was reported to standardize the height of stepping for individuals of various heights. We designed a study to validate this model using a three-minute single-stage step test for predicting VO2 max in women.
View Article and Find Full Text PDFPhysical fitness has been reported to be inversely related to coronary heart disease and other health related problems. One of the most valid means of assessing physical fitness is the test of aerobic capacity. Aerobic capacity is the greatest rate at which the body can consume oxygen and represents the most efficient integration of the various physiological processes which make up the oxygen transport system.
View Article and Find Full Text PDFThis study investigated the relationship between inherent muscle length and torque production in 59 healthy women. We recorded nondominant ankle range-of-motion values for each subject. These values were partitioned into quartiles for two knee positions.
View Article and Find Full Text PDFTo ascertain the use of professional personnel in health care among secondary school athletics in Alabama, a survey was sent to all high schools in the state. Smaller schools (classified 1A) are located an average of 10.8 miles from the nearest medical facility, while for larger schools (classified 4A) the average is 3.
View Article and Find Full Text PDFPhys Sportsmed
January 1986
In brief: A sports medicine survey of 119 public high schools in Alabama showed that the smaller schools are farther from medical facilities and have less space and equipment for injury management than larger schools. Primary care or family physicians are used most often as team physicians, but the availability of physicians at practice and at sports events other than football is limited. Many schools have no team physician, most lack athletic trainers, and about half of the coaches do not feel prepared to handle a medical emergency.
View Article and Find Full Text PDFIn brief: The authors analyzed 1,877 high school football injuries to determine differences between game and practice injuries. The results indicate that games are more dangerous per time unit of exposure than practice. Significantly more contusions, especially to the trunk, occurred during games, and strains occurred more frequently during practice.
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