Carl D.R.,University of Utah |
Carl D.R.,Heritage Research Group |
Armentrout P.B.,University of Utah
ChemPhysChem | Year: 2013
The sequential bond energies of Mg2+(H2O)x complexes, in which x=2-10, are measured by threshold collision-induced dissociation in a guided ion beam tandem mass spectrometer. From an electrospray ionization source that produces an initial distribution of Mg 2+(H2O)x complexes in which x=7-10, complexes down to x=3 are formed by using an in-source fragmentation technique. Complexes smaller than Mg2+(H2O)3 cannot be formed in this source because charge separation into MgOH+(H2O) and H3O+ is a lower-energy pathway than simple water loss from Mg2+(H2O)3. The kinetic energy dependent cross sections for dissociation of Mg2+(H2O)x complexes, in which x=3-10, are examined over a wide energy range to monitor all dissociation products and are modeled to obtain 0 and 298 K binding energies. Analysis of both primary and secondary water molecule losses from each sized complex provides thermochemistry for the sequential hydration energies of Mg2+ for x=2-10 and the first experimental values for x=2-4. Additionally, the thermodynamic onsets leading to the charge-separation products from Mg2+(H2O)3 and Mg2+(H 2O)4 are determined for the first time. Our experimental results for x=3-7 agree well with quantum chemical calculations performed here and previously calculated binding enthalpies, as well as previous measurements for x=6. The present values for x=7-10 are slightly lower than previous experimental results and theory, but within experimental uncertainties. On a collision course: Threshold collision-induced dissociation and guided ion beam tandem mass spectrometry are used to determine the binding enthalpies for Mg2+(H2O)x complexes in which x=2-10 (see picture). The dominant process that takes place for all Mg2+(H 2O)x complexes is the loss of a single water molecule. Moreover, the first experimental hydration energies for Mg2+(H 2O)2 to Mg2+(H2O)4 are determined. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source
Selcuk S.,Heritage Research Group
ACS Symposium Series | Year: 2014
An overview of core competencies and skills that are desired specifically within the chemical industry is presented in this chapter. The core competencies discussed below are desired in almost all work environments. Until these competencies are addressed as a part of an academic curriculum, self-education and self-preparation will help you transition smoothly from an academic mind-set to that of an industrial chemist or chemical engineer. Learn how the chemical industry of interest functions and develop yourself within that industry by focusing on these core competencies. © 2014 American Chemical Society. Source
Kriech A.J.,Heritage Research Group
Journal of occupational and environmental hygiene | Year: 2010
Field studies were conducted at paving and roofing sites to compare the German Institute for Occupational Safety and Health of the German Social Accident Insurance (IFA) Fourier transform infrared spectroscopy method 6305 with the National Institute for Occupational Science and Health (NIOSH) benzene soluble fraction method 5042 plus total organic matter. Sampling using both methods was performed in multiple bitumen-related workplace environments. To provide comparable data all samplings were performed in parallel, and the analytical data were related to the same representative bitumen condensate standard. An outline of the differences between the sampling and analytical methods is provided along with comparative data obtained from these site investigations. A total of 55 bitumen paving sampler pairs were reported and statistical comparisons made using the 35 pairs of detectable data. First, the German inhalable aerosol data and the NIOSH benzene soluble fraction (BSF) method showed a correlation coefficient of R2= 0.88 (y((BSF))= 0.60 x((aerosol))). Second, the aerosol data compared with total particulate matter (TPM) show a R2 of 0.83 (y((TPM))= 1.01 x((aerosol))). Finally, total organic matter (TOM) and "aerosol + vapor" data yielded a R2 of 0.78 (y((TOM))= 0.44 x((aerosol+vapor))). Twenty-nine pairs of roofing data were also collected; 37% were below the limit of detection. When comparing the TOM data with the aerosol + vapor data, using the 13 of 29 pairs where both samplers showed detectable results, the relationship was y((TOM))= 0.74 x((aerosol+vapor)) (R2= 0.91). The slopes within these equations provide predictive factors between these sampling and analysis methods; intended for use with large sets of data, they are not applicable to single point measurements. Source
Heritage Research Group | Date: 2014-03-11
Asphalt binders which contain polysilazanes that are produced by reacting chlorosilanes with ammonia and other optional solvents. Sources for the chlorosilanes include waste chlorosilanes such as direct process residue. The polysilazanes function as anti-stripping agents.
Heritage Research Group | Date: 2014-03-11
Guardrail support brackets for use in securing safety guardrails during the construction of MSE wall systems. The guardrail support brackets include a clamping portions that secure the support brackets to the top of adjacent wall panels, vertical support posts that are coupled to the clamping portions in such a manner to allow the vertical support posts to extend above or below the clamping portions, and guardrail supports that secure elongate guardrail elements to the vertical support posts.