The moderating role of equity sensitivity on the optimism and stress relationship

Research supports optimism as a predictor of how well individuals are able to cope with stress (Chang, Rand, & Strunk, 2007; Riolli & Savicki, 2003). Additionally perceived inequity is considered as a stressor (Taris, Peeters, Le Blanc, Scheurs, & Schaufeli, 2001) and the extent to which individuals perceive inequity is determined by equity sensitivity (Miles, Hatfield, Huseman, 1989). The present research proposes a new framework in which the relationship between optimism and feelings of inequity is moderated by equity sensitivity. The final part of the framework analyzes perceived inequity’s relationship to perceived stress. The results indicated that optimism’s relationship was actually mediated by positive affect. There was mixed support for a significant interaction between optimism and equity sensitivity in its relationship to perceived inequity. Perceived inequity was a predictor of stress

Bio-mass for biomass: biological mass spectrometry techniques for biomass fast pyrolysis oils

Biomass fast pyrolysis oils, or bio-oils, are a promising renewable energy source to supplement or replace petroleum-based products and fuels. However, there is a current lack of understanding about the pyrolysis process which creates a bottleneck towards making biomass pyrolysis an economically feasible option. In order to address this bottleneck, this research focuses on developing high resolution mass spectrometry (HRMS) techniques to address biomass pyrolysis at the molecular-level. The first attempt at analyzing bio-oils with HRMS employs laser desorption ionization and LTQ-Orbitrap MS to successful identify over 100 compounds. These compounds consist of 3-6 oxygens and have double-bond equivalents (DBE) of 9-17. A petroleomic analysis and comparison of the bio-oil to the low-mass components in hydrolytic lignin suggest that these compounds are dimers and trimers of depolymerized lignin. A wider variety of bio-oil compounds, specifically volatile and non-volatile compounds, could be characterized with electrospray ionization (ESI). Specifically, (-) ESI allows for the characterization of over 800 molecular compounds, of which about 40 of these were previously known in GC-MS. These compounds include cellulose- and hemicellulose-derived pyrolysis products as well as lignin-derived pyrolysis products. A comparative study of three common HRMS was also performed to validate the methodology and to investigate differences in mass discrimination and resolution. This led to the development of a novel spectral stitching technique that combines datasets from different HRMS together. By stitching the datasets together inherent instrument limitations (e.g. like mass discrimination and resolution) can be addressed. The resulting stitched mass spectrum gives rise to a more comprehensive picture of bio-oil. Lastly, a pioneering technique that utilizes HRMS to monitor biomass fast pyrolysis in real-time has been developed. A fast-scanning time-of-flight mass spectrometer with a soft ionization source and a drop-in micropyrolyzer is used to provide insights into biomass pyrolysis that are not possible with traditional techniques. For example, metastable intermediates of cellulose pyrolysis could be identified and monitored with this novel approach. Also, fundamental pyrolysis studies, such as the effect of biomass shape and thickness, are possible with this technique due to the high sensitivity and time resolution of the time-of-flight mass spectrometer

Optimization of biomass fast pyrolysis for the production of monomers

Fast pyrolysis is a promising method for producing advanced biofuels and chemicals from lignocellulosic biomass. The process will however require further optimization to produce fuels and chemicals at a price competitive to conventional fossil fuel-derived products. Research in this dissertation focuses on both pre- and post-processes for optimizing fast pyrolysis to produce increased yields of valuable anhydrosugars and phenolic monomers. The concept of alkali and alkaline earth metal (AAEM) passivation using sulfuric acid had only previously been demonstrated in batch micropyrolyzer trials. A bench-scale, continuous-flow auger pyrolyzer was used in this work to demonstrate AAEM passivation on both woody and herbaceous feedstocks. Alkali and alkaline earth metal passivation of red oak and switchgrass increased total sugars by more than 105% and 260%, respectively. Light oxygenates simultaneously decreased by nearly 50% from each feedstock. The synchronous increase in sugars and decrease in light oxygenates provides evidence of the hypothesis that AAEM passivation prevents pyranose ring fragmentation and promotes glycosidic bond cleavage in holocellulose. An undesirable consequence of AAEM passivation was an increase in biochar from both lignin and carbohydrates. Demonstration of the enhanced production of sugars from AAEM passivated feedstocks in a continuous auger pyrolyzer at the kilogram scale is an important step in determining the feasibility of using fast pyrolysis to produce sugars from lignocellulosic biomass. Lignin-derived biochar increased from AAEM passivated feedstocks which led to suspicions that thermally active AAEMs catalyze lignin pyrolysis. Effect of thermally active AAEMs on lignin pyrolysis was therefore investigated in more detail. Experimental results indicated that sodium was the most active AAEM on lignin pyrolysis in which it increased overall volatile aromatic monomers by over 16% compared to the control. Alkali metals as a group both increased char and decreased alkenyl side chains amongst volatile aromatics. Alkenyl side chains are known to result from the cleavage of certain bonds within the lignin structure. Therefore AAEMs are predicted to catalyze the cleavage of linkages within the lignin structure during pyrolysis. The rate at which pyrolysis vapors are cooled in bio-oil collection equipment has been noted to have an influence on bio-oil composition, however prior to this research has never been quantified. A novel cold-gas quench system was developed that utilizes liquid nitrogen to quickly quench pyrolysis products, which produced a more than seven fold increase in cooling rate compared to a conventional shell and tube condenser. The increased cooling rate and elimination of radial temperature gradients in the quench system increased levoglucosan yield from cellulose by 23% compared to the conventional system

Novel instrumentation for tracking molecular products in fast pyrolysis of carbohydrates with sub-second temporal resolution

Despite recent advances, little has been experimentally established regarding the detailed chemical processes that occur during biomass pyrolysis reactions. We developed a new technique that allows for the monitoring of each molecular product from fast pyrolysis with ∼0.2 s temporal resolution. This was achieved by directly coupling a micropyrolyzer with a time-of-flight mass spectrometer via a soft ionization. Molecular products studied were produced in thin-film pyrolysis of a series of glucose-based carbohydrates. Unprecedented details of the pyrolysis reaction process were revealed, including the timescale of molecular product formation and the existence of metastable intermediates. Small carbohydrates are completely pyrolyzed within one second and as short as one-half second for glucose pyrolysis. Individual time profiles could be extracted and examined for each molecular product. Additionally, the effect of sample dimensions on the pyrolysis of cellulose and α-cyclodextrin, as both thin films and particles, was studied. A surprising time delay of one second is observed for the thin-film pyrolysis of cellulose and α-cyclodextrin, which is attributed to the transition to the molten phase. When a large amount of cellulose or α-cyclodextrin is pyrolyzed, random fluctuations of temporal profiles are observed and explained as coming from aerosol ejections. This is well correlated with the high abundance of non-volatile products such as cellobiosan that cannot be detected in typical GC–MS or pyrolysis GC–MS analysis

Regiospecific analysis of Mono and Diglycerides in Glycerolysis products by GC x GC TOF-MS.

Comprehensive bidimensional gas chromatography coupled with time-of-flight mass spectrometry (GC × GC-TOF-MS) was used for the characterization of regiospecific mono- and diglycerides (MG-DG) content in the glycerolysis products derived from five different lipids included lard (LA), sun flower seed oil (SF), corn oil (CO), butter (BU), and palm oil (PA). The combination of fast and high temperature non-orthogonal column set namely DB17ht (6 m × 0.10 mm × 0.10 μm) as the primary column and SLB-5 ms (60 cm × 0.10 mm × 0.10 μm) as the secondary column was applied in this work. System configuration involved high oven ramp temperature to obtain precise mass spectral identification and highest effluent’s resolution. 3-Monopalmitoyl-sn-glycerol (MG 3-C16) was the highest concentration in LA, BU and PA while monostearoyl-sn-glycerol (MG C18) in CO and 1,3-dilinoleol-rac-glycerol (DG C18:2c) in SF. Principal component analysis accounted 82% of variance using combination of PC1 and PC2. The presence of monostearoyl-sn-glycerol (MG C18), 3-Monopalmitoyl-sn-glycerol (MG 3-C16), 1,3-dilinoleol-rac-glycerol (DG C18:2c), 1,3-dipalmitoyl-glycerol (DG 1,3-C16), and 1,3-dielaidin (DG C18:1t) caused differentiation of the samples tested

Prots: A fragment based protein thermo‐stability potential

Designing proteins with enhanced thermo‐stability has been a main focus of protein engineering because of its theoretical and practical significance. Despite extensive studies in the past years, a general strategy for stabilizing proteins still remains elusive. Thus effective and robust computational algorithms for designing thermo‐stable proteins are in critical demand. Here we report PROTS, a sequential and structural four‐residue fragment based protein thermo‐stability potential. PROTS is derived from a nonredundant representative collection of thousands of thermophilic and mesophilic protein structures and a large set of point mutations with experimentally determined changes of melting temperatures. To the best of our knowledge, PROTS is the first protein stability predictor based on integrated analysis and mining of these two types of data. Besides conventional cross validation and blind testing, we introduce hypothetical reverse mutations as a means of testing the robustness of protein thermo‐stability predictors. In all tests, PROTS demonstrates the ability to reliably predict mutation induced thermo‐stability changes as well as classify thermophilic and mesophilic proteins. In addition, this white‐box predictor allows easy interpretation of the factors that influence mutation induced protein stability changes at the residue level. Proteins 2012; © 2011 Wiley Periodicals, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/89526/1/23163_ftp.pd

Simultaneous analysis of free amino acids and biogenic amines in honey and wine samples using in loop orthophthalaldeyde derivatization procedure

This work presents a RP-HPLC method for the simultaneous quantification of free amino acids and biogenic amines in liquid food matrices and the results of the application to honey and wine samples obtained from different production processes and geographic origins. The developed methodology is based on a pre-column derivatization with o-phthaldialdehyde carried out in the sample injection loop. The compounds were separated in a Nova-Pack RP-C18 column (150 mm × 3.9 mm, 4 μm) at 35 °C. The mobile phase used was a mixture of phase A: 10 mM sodium phosphate buffer (pH 7.3), methanol and tetrahydrofuran (91:8:1); and phase B: methanol and phosphate buffer (80:20), with a flow rate of 1.0 ml/min. Fluorescence detection was used at an excitation wavelength of 335 nm and an emission wavelength of 440 nm. The separation and quantification of 19 amino acids and 6 amines was carried out in a single run as their OPA/MCE derivatives elute within 80 min, ensuring a reproducible quantification. The method showed to be adequate for the purpose, with an average RSD of 2% for the different amino acids; detection limits varying between 0.71 mg/l (Asn) and 8.26 mg/l (Lys) and recovery rates between 63.0% (Cad) and 98.0% (Asp). The amino acids present at the highest concentration in honey and wine samples were phenylalanine and arginine, respectively. Only residual levels of biogenic amines were detected in the analysed samples

Comparison of product distribution, content and fermentability of biomass in a hybrid thermochemical/biological processing platform

Thermochemical processing is a promising method for the rapid depolymerization of biomass. This study investigated switchgrass, corn stover, red oak, hybrid poplar, and loblolly pine in terms of heteropolymer and elemental composition, and the distribution and composition of the fast pyrolysis products. Corn stover differed from other biomass types in that less of the biomass was recovered as sugar or phenolic oil (PO) and more of the biomass was recovered as bio-char and bio-gas. The sugar-rich aqueous stream recovered from the bio-oil heavy fraction was characterized in terms of sugar content and distribution, inhibitor content, and ability to support production of ethanol by Escherichia coli KO11 + lgk as a model biorenewable product. Levoglucosan was the most abundant sugar from each type of biomass, followed by either xylose or cellobiosan. For hybrid poplar, cellobiosan accounted for 30 wt% of the total sugar pool. Each of the sugar streams also contained a variety of inhibitors, particularly 5-hydroxymethylfurfural (5-HMF) and methylcyclopentenolone. Methylcyclopentenolone, maple lactone, was found to decrease the specific growth rate of E. coli by 50% when present at 0.72 wt%, indicating that it is less toxic than furfural, acetic acid and guaiacol. Sugars produced from switchgrass contained 4-fold less contaminants on a per-sugar basis than those from poplar and pine. All of the sugar streams contained too many inhibitors to be used at an industrially feasible concentration without additional detoxification. The poplar-derived pyrolytic sugar syrup was particularly inhibitory, possibly due to the high abundance of aromatic hydrocarbons, such as xylenes, and anisoles