12 research outputs found
Tandem Mass Spectrometry Measurement of the Collision Products of Carbamate Anions Derived from CO2 Capture Sorbents: Paving the Way for Accurate Quantitation
The reaction between CO2 and aqueous amines to produce a charged carbamate product plays a crucial role in post-combustion capture chemistry when primary and secondary amines are used. In this paper, we report the low energy negative-ion CID results for several anionic carbamates derived from primary and secondary amines commonly used as post-combustion capture solvents. The study was performed using the modern equivalent of a triple quadrupole instrument equipped with a T-wave collision cell. Deuterium labeling of 2-aminoethanol (1,1,2,2,-d4-2-aminoethanol) and computations at the M06-2X/6-311++G(d,p) level were used to confirm the identity of the fragmentation products for 2-hydroxyethylcarbamate (derived from 2-aminoethanol), in particular the ions CNâ, NCOâ and facile neutral losses of CO2 and water; there is precedent for the latter in condensed phase isocyanate chemistry. The fragmentations of 2-hydroxyethylcarbamate were generalized for carbamate anions derived from other capture amines, including ethylenediamine, diethanolamine, and piperazine. We also report unequivocal evidence for the existence of carbamate anions derived from sterically hindered amines (Tris(2-hydroxymethyl)aminomethane and 2-methyl-2-aminopropanol). For the suite of carbamates investigated, diagnostic losses include the decarboxylation product (âCO2, 44 mass units), loss of 46 mass units and the fragments NCOâ (m/z 42) and CNâ (m/z 26). We also report low energy CID results for the dicarbamate dianion (âO2CNHC2H4NHCO2â) commonly encountered in CO2 capture solution utilizing ethylenediamine. Finally, we demonstrate a promising ion chromatography-MS based procedure for the separation and quantitation of aqueous anionic carbamates, which is based on the reported CID findings. The availability of accurate quantitation methods for ionic CO2 capture products could lead to dynamic operational tuning of CO2 capture-plants and, thus, cost-savings via real-time manipulation of solvent regeneration energies
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Audiological and genetic studies on large families with non-syndromic deafness
Recent progress in gene identification for non-syndromic deafness demonstrates the efficacy of using a large family approach. To assess if clinical and genetic heterogeneity exists in families with non-syndromic hearing impairment we have identified five large Chinese families suitable for investigating clinical and genetic heterogeneity. Five Chinese families spanning 5-6 generations and comprising 48 to 172 members were identified. The auditory phenotype was investigated with pure tone audiometry and DPOAEs. Age at onset of hearing loss was compared between generations by using life-table analysis and the Wilcoxon test in a family. All statistical analyses were performed using the SAS statistical package. Screening for GJB2 and mitochondrial mutations was performed. Two families showing maternal inheritance were found to have the mitDNA A1555G mutation. Subjects with the A1555G mutation exhibit a normal to profound, progressive deafness. Anticipation of the hearing loss was observed in one of these two families. The other three families are segregating for a late onset form of progressive hearing loss with normal vestibular function. DPOAEs from a group of possible gene carriers with normal audiograms in two families have shown a substantial difference from that of controls. Our data show the existence of clinical and genetic heterogeneity in the five large Chinese deaf families. Marked differences in severity of hearing loss, along with a lack of exposure to aminoglycosides and the presence of anticipation in the mitDNA deafness suggest the presence of a modifier. DPOAEs may be a sensitive test for a subclinical change in carriers. Identification of gene(s) for deafness should allow us to better understand the molecular basis of deafness and to improve patient care
Efficiency Measurement for Production and Wastewater Abatement Activity Using Network Data Envelopment Analysis: The Case of Korean Industrial Complex
Mesostructured or Alumina-mesostructured Silica SBA-16 as Potential Support for NOx Reduction and Ethanol Oxidation
Sustainable Mesoporous Carbons as Storage and Controlled-Delivery Media for Functional Molecules
Energyâefficient hybrid A/C and freshwater production system proposed for high latent load spaces
Search for a low mass neutral Higgs boson in Z0 decay
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