ENDOR and ESEEM studies of a cyanide adduct of transferrin

Information about the ligand environment of the iron binding sites in a cyanide adduct of transferrin was obtained by an analysis of powder-type ENDOR and ESEEM spectra. The low-spin cyanide adduct of transferrin is formed only in the C-terminal site of the protein and is characterized by a rhombic EPR spectrum. Earlier work demonstrated that three cyanide groups are necessary to form the adduct, but it wasn\u27t clear whether these groups were coordinated directly to the metal or to cationic sites on the protein. The ENDOR spectra of the \sp{13}CN adduct showed one set of \sp{13}C ENDOR resonances which probably corresponds to only one or two of the CN groups, the other(s) being ENDOR silent. Simulations of the ENDOR line positions indicate a substantial isotropic coupling and smaller dipolar couplings. From an analysis of the orientation dependent dipolar term it is concluded that the carbon giving rise to the ENDOR signals lies along the g\sb{\rm xx} axis of the g-tensor. The iron-carbon distance was calculated based on a point dipole model and a model in which the ground state metal-based d\sb{\rm xy} orbital of the electron was considered explicitly. ESEEM studies with C\sp{15}N indicated that there are at least two equivalent CN groups coordinated to the iron center. The maximum hyperfine coupling for the nitrogen was observed near g\sb{\rm xx} which is consistent with the ENDOR results which placed the carbon of the cyanide group on the g\sb{\rm xx} axis. There is a substantial hyperfine contribution along g\sb{\rm zz} which indicates that the CN bond is not aligned along the g\sb{\rm xx} axis. The lack of resolved couplings in the spectrum along g\sb{\rm yy} makes it impossible to determine the nitrogen position exactly. The ESEEM spectra of the C\sp{14}N adduct were complicated, presumably because the Zeeman and hyperfine terms did not cancel at the spectrometer frequencies used. The ESEEM and ENDOR spectra of the D\sb2O solvent exchanged adduct demonstrated that water does not coordinate directly to the iron. The ESEEM of the g\sp\prime = 4.3 signal which arises from the high-spin N-terminal site was also studied and the observed ESEEM resonances were attributed to histidine nitrogen

Ice in the Antarctic polar stratosphere

On six occasions during the 1987 Airborne Antarctic Ozone Experiment, the Polar Stratospheric Cloud (PSC) ice crystals were replicated over the Palmer Peninsula at approximately 70 deg South. The sampling altitude was approximately 60 to 65 thousand feet, the temperature range was -83.5 to -72C and the atmosphere was subsaturated in all cases. The collected crystals were predominantly complete and hollow prismatic columns with maximum dimensions up to 217 microns. Evidence of scavenging of submicron particles was detected on several crystals. While the replicated crystal sizes were larger than anticipated, their relatively low concentration results in a total surface area less than one tenth that of the sampled aerosol particles. The presence of large crystals suggest that PSC ice crystals can play a very important role in stratospheric dehydration processes

Thermodynamics of Water Superheated in the Microwave Oven

A simple visual demonstration is proposed that provokes thinking about the elementary thermodynamics of heating and boiling. Water is conveniently heated above its normal boiling point in a microwave oven in a glass microwave oven teapot. Water stops boiling soon after heating is interrupted, but subsequently added rough particles can still act as nucleation centers for a brief, spectacular burst of steam bubbles. The heat to make those steam bubbles obviously comes from the water itself, so that one can conclude that the boiling water was superheated, which is confirmed with a thermometer. Besides illustrating chemical thermodynamics, the demonstration also shows why safety precautions are usually taken in the laboratory to prevent superheating. Details of the observations are discussed by giving background on the nucleation of steam bubbles

Programs for calculating cell parameters in electron and X-ray diffraction

Ten programs for calculating cell parameters from single crystal electron diffraction patterns are presented. Most of the programs, written for use with a programmable desk calculator, are also applicable to X-ray diffraction work. The programs can be used to calculate d-spacings from electron diffraction plate measurements, and to determine cell data (including interplanar angles and zone angles) for all crystal systems. A program for rhombohedral-hexagonal conversions and one for matching crystal data from standards with apparent crystal parameters found in diffraction patterns are included. Because they allow rapid determination of data not present in X-ray listings or elsewhere in the literature, the programs facilitate identification of unknowns

Mount St. Helens aerosol evolution

Stratospheric aerosol samples were collected using a wire impactor during the year following the eruption of Mount St. Helens. Analysis of samples shows that aerosol volume increased for 6 months due to gas-to-particle conversion and then decreased to background levels in the following 6 months

Antarctic polar stratospheric aerosols: The roles of nitrates, chlorides and sulfates

Nitric and hydrochloric acids have been postulated to condense in the winter polar stratosphere to become an important component of polar stratospheric clouds. One implication is that the removal of NO(y) from the gas phase by this mechanism allows high Cl(x) concentrations to react with O3, because the formation of ClNO3 is inhibited. Contributions of NO3 and Cl to the stratospheric aerosol were determined during the 1987 Airborne Antarctic Ozone Experiment by testing for the presence of nitrates and chlorides in the condensed phase. Aerosol particles were collected on four 500 micron diameter gold wires, each pretreated differently to give results that were specific to certain physical and chemical aerosol properties. One wire was carbon-coated for concentration and size analyses by scanning electron microscopy; X-ray energy dispersive analyses permitted the detection of S and Cl in individual particles. Three more wires were coated with Nitron, barium chloride and silver nitrate, respectively, to detect nitrate, sulfate and chloride in aerosol particles. All three ions, viz., sulfates, nitrates and chlorides were detected in the Antarctic stratospheric aerosol. In terms of number concentrations, the aerosol was dominated by sulfates, followed by chlorides and nitrates. An inverse linear regression can be established between nitrate concentrations and ozone mixing ratio, and between temperature and nitrates

Predicting the Pursuit of Post-Secondary Education: Role of Trait Emotional Intelligence in a Longitudinal Study

Trait Emotional Intelligence (EI) is a constellation of emotional self-perceptions and dispositions related to perceiving, understanding, using, and managing emotions of self and others. Although higher trait EI has been implicated in post-secondary success among university students. There is lack of evidence for whether it predicts the pursuit of post-secondary education (PSE) in emerging adulthood. This was the first study to investigate the role of trait EI in PSE pursuit using a large, nationally-representative sample of Canadian young adults who participated in the National Longitudinal Survey for Children and Youth (NLSCY). Participants in this dataset reported on their PSE status at three biennial waves (age 20–21, 22–23, and 24–25), and completed a four-factor self-report scale for trait EI (Emotional Quotient Inventory: Mini) at ages 20–21 and 24–25. Higher trait EI subscale scores were significantly associated with greater likelihood of PSE participation both concurrently, and at 2- and 4-year follow-ups. Overall, these associations were larger for men than women. The finding that these links persisted over a multi-year period is particularly promising, as it represents an important validation step toward further investment in socioemotional competencies as part of youth development interventions

Nature, origin, transport and deposition of andosol parent material in south-central Chile (36-42°S)

Author Posting. © Elsevier B.V., 2007. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in CATENA 73 (2008): 10-22, doi:10.1016/j.catena.2007.08.003.The andosols of south-central Chile (36-42°S) are developed on yellow-brown loams that cover the region with a thickness of several meters. In the literature, several hypotheses concerning the nature, origin, mode of transport and deposition of the andosol parent material have been advanced but no general agreement has been found. In this paper, we test these hypotheses by analyzing new representative outcrops located around Icalma (38°50’S) and Puyehue (40°40’S) lakes by a plurimethodological approach. Our data demonstrate that the andosol parent material has the typical mineralogical and geochemical signature of the regional volcanism and that these deposits are postglacial in age. The grain size of the deposits and the morphology of the coarse grains evidence that most of these particles haven’t been re-transported by wind but are direct volcanic ash falls deposited throughout the Late Glacial and Holocene. Because of the prevailing westerly winds, most of them have been transported to the East. Following the deposition of the volcanic particles, weathering and pedogenetic processes have transformed part of the volcanic glasses and plagioclases into allophane and have wiped out the original layering. This work demonstrates that most of the andosols that occur in the Andes and in the eastern part of the Intermediate Depression of south-central Chile are developed on volcanic ashes directly deposited by successive volcanic eruptions throughout the Late Glacial and Holocene.This research is supported by the Belgian OSTC project EV/12/10B "A continuous Holocene record of ENSO variability in southern Chile"