Quantitative infrared spectroscopy of minor constituents of the Earth's atmosphere

We obtain quantitative laboratory spectroscopic measurements of molecular constituents which are of importance in understanding the health of the Earth's atmosphere, and, in particular, emphasize those species which are important for understanding stratospheric kinetics or are used for long term monitoring of the stratosphere. Our measurements provide: (1) line and band intensity values which are needed to establish limits of detectability for as yet unobserved species and to quantify the abundance of those species which are observed; (2) line-positions, -half widths and pressure induced shifts are all needed for remote sensing techniques, and (3) data on the above basic molecular parameters at temperatures and pressures appropriate for the real atmosphere

Inhomogeneous models of the Venus clouds containing sulfur

Based on the suggestion that elemental sulfur is responsible for the yellow color of Venus, calculations are compared at 3.4 microns of the reflectivity phase function of two sulfur containing inhomogeneous cloud models with that of a homogeneous model. Assuming reflectivity observations with 25% or less total error, comparison of the model calculations leads to a minimum detectable mass of sulfur equal to 7% of the mass of sulfuric acid for the inhomogeneous drop model. For the inhomogeneous cloud model the comparison leads to a minimum detectable mass of sulfur between 17% and 38% of the mass of the acid drops, depending upon the actual size of the large particles. It is concluded that moderately accurate 3.4 microns reflectivity observations are capable of detecting quite small amounts of elemental sulfur at the top of the Venus clouds

The Kinetics of Early T and B Cell Immune Recovery after Bone Marrow Transplantation in RAG-2-Deficient SCID Patients

The kinetics of T and B cell immune recovery after bone marrow transplantation (BMT) is affected by many pre- and post-transplant factors. Because of the profoundly depleted baseline T and B cell immunity in recombination activating gene 2 (RAG-2)-deficient severe combined immunodeficiency (SCID) patients, some of these factors are eliminated, and the immune recovery after BMT can then be clearly assessed. This process was followed in ten SCID patients in parallel to their associated transplant-related complications. Early peripheral presence of T and B cells was observed in 8 and 4 patients, respectively. The latter correlated with pre-transplant conditioning therapy. Cells from these patients carried mainly signal joint DNA episomes, indicative of newly derived B and T cells. They were present before the normalization of the T cell receptor (TCR) and the B cell receptor (BCR) repertoire. Early presentation of the ordered TCR gene rearrangements after BMT occurred simultaneously, but this pattern was heterogeneous over time, suggesting different and individual thymic recovery processes. Our findings early after transplant could suggest the long-term patients' clinical outcome. Early peripheral presence of newly produced B and T lymphocytes from their production and maturation sites after BMT suggests donor stem cell origin rather than peripheral expansion, and is indicative of successful outcome. Peripheral detection of TCR excision circles and kappa-deleting recombination excision circles in RAG-2-deficient SCID post-BMT are early markers of T and B cell reconstitution, and can be used to monitor outcome and tailor specific therapy for patients undergoing BMT

Regrets Associated with Providing Healthcare: Qualitative Study of Experiences of Hospital-Based Physicians and Nurses

Regret is an unavoidable corollary of clinical practice. Physicians and nurses perform countless clinical decisions and actions, in a context characterised by time pressure, information overload, complexity and uncertainty

Role of Active Site Rigidity in Activity: MD Simulation and Fluorescence Study on a Lipase Mutant

Relationship between stability and activity of enzymes is maintained by underlying conformational flexibility. In thermophilic enzymes, a decrease in flexibility causes low enzyme activity while in less stable proteins such as mesophiles and psychrophiles, an increase in flexibility is associated with enhanced enzyme activity. Recently, we identified a mutant of a lipase whose stability and activity were enhanced simultaneously. In this work, we probed the conformational dynamics of the mutant and the wild type lipase, particularly flexibility of their active site using molecular dynamic simulations and time-resolved fluorescence techniques. In contrast to the earlier observations, our data show that active site of the mutant is more rigid than wild type enzyme. Further investigation suggests that this lipase needs minimal reorganization/flexibility of active site residues during its catalytic cycle. Molecular dynamic simulations suggest that catalytically competent active site geometry of the mutant is relatively more preserved than wild type lipase, which might have led to its higher enzyme activity. Our study implies that widely accepted positive correlation between conformation flexibility and enzyme activity need not be stringent and draws attention to the possibility that high enzyme activity can still be accomplished in a rigid active site and stable protein structures. This finding has a significant implication towards better understanding of involvement of dynamic motions in enzyme catalysis and enzyme engineering through mutations in active site

The search for the ideal biocatalyst

While the use of enzymes as biocatalysts to assist in the industrial manufacture of fine chemicals and pharmaceuticals has enormous potential, application is frequently limited by evolution-led catalyst traits. The advent of designer biocatalysts, produced by informed selection and mutation through recombinant DNA technology, enables production of process-compatible enzymes. However, to fully realize the potential of designer enzymes in industrial applications, it will be necessary to tailor catalyst properties so that they are optimal not only for a given reaction but also in the context of the industrial process in which the enzyme is applied

Characterisation of a new family of carboxyl esterases with an OsmC domain

Proteins in the serine esterase family are widely distributed in bacterial phyla and display activity against a range of biologically produced and chemically synthesized esters. A serine esterase from the psychrophilic bacterium Pseudoalteromonas arctica with a C-terminal OsmC-like domain was recently characterized; here we report on the identification and characterization of further putative esterases with OsmC-like domains constituting a new esterase family that is found in a variety of bacterial species from different environmental niches. All of these proteins contained the Ser-Asp-His motif common to serine esterases and a highly conserved pentapeptide nucleophilic elbow motif. We produced these proteins heterologously in Escherichia coli and demonstrated their activity against a range of esterase substrates. Two of the esterases characterized have activity of over two orders of magnitude higher than other members of the family, and are active over a wide temperature range. We determined the crystal structure of the esterase domain of the protein from Rhodothermus marinus and show that it conforms to the classical α/β hydrolase fold with an extended ‘lid’ region, which occludes the active site of the protein in the crystal. The expansion of characterized members of the esterase family and demonstration of activity over a wide-range of temperatures could be of use in biotechnological applications such as the pharmaceutical, detergent, bioremediation and dairy industries

INTENSITY AND POSITION MEASUREMENTS OF CARBON DIOXIDE LINES IN THE 4370 TO 4640 cm−1cm^{-1} REGION

Author Institution: NASA AMES Research Center, , MS 245/4, Moffett Field, CA 94035-1000.$^{1}$B. Bezard, C. de Bergh, D. Crisp, and J.-P. Maillard, Nature 245, 508 (1990). $^{2}$C. R. Pollock, F.R. Petersen, D. A. Jennings, and J. S. Wells, J. Mol. Spectrosc. 99, 357 (1983).A set of 14 spectra of the carbon dioxide absorption bands in the 4300 to 4700 $cm^{-1}$ region were obtained with a BOMEM DA3.002 FTS and a White cell using absorption path lengths between 507 and 1307 meters. The principal purpose of this work was to make the first laboratory measurements of the transition moment and Herman-Wallis intensity parameters of the $^{12} C^{16} O_{2}$ $(31^{1}O)_{IV} -(00^{\circ}00)$ band at $4416.15 cm^{-1}$. This weak band was recently found to be prominent in the thermal emission spectrum of the dark side of $Venus^{1}$. Our measured rotationless transition moment of this band is $R^{2} = (1.41\pm0.14)$ $x10^{-11}$ $Debye^{2}$. Line positions for this band were calibrated using the 2-0 $band^{2}$ of CO. The spectra of CO and $CO_{2}$ were recorded simultaneously with a small amount of added CO to the $CO_{2}$. In this spectral region we have also recorded data which is suitable for intensity and positional work on the $(31^{1}0)_{III} - (00^{\circ}0)$, $(32^{2}0)_{III} - (01^{1}0)$ and $(40^{\circ}0)_{IV} - (01^{1}0)$ bands of $^{12}C^{16}O_{2}$ and the $(00^{\circ}2)_{I} - (00^{\circ}0)$ band of $^{13}C^{16}O^{18}O$

INFRARED SPECTROSCOPY WITH AN OPTICAL PARAMETRIC OSCILLATOR: THE SHIFT AND STRENGTH OF THE S2S_{2}(1) HYDROGEN LINE

$^{1}$A.R.W. McKellar, Ap. J. 185, L53 (1973). $^{2}$A.R.W. McKellar. Can. J. Phys. 51, 389 (1973).""Author Institution: Ames Research CenterA tunable laser was used in combination with a 25-m base-path White cell and a 5-m spectrometer to obtain measurements of the equivalent width and frequency of the $S_{2}$(l) line of hydrogen over the density range of one to four amagat. The long optical path permits ratioing (I/I$^{\circ}$) to be done with a single detector. The equivalent widths analyzed in terms of a Galatry line shape yield a line strength in excellent agreement with the ab initio calculations. The pressure shift of the $S_{2}$(l) frequency is approximately twice that measured for the $S_{1}$(l) line. This result indicates a perturbation of the vibrational force constant and is consistent with results obtained with hydrogen $deuteride.^{1,2}