Desorption electrospray ionization-mass spectrometry (DESI-MS) was evaluated for the detection of proteins ranging in molecular weight from 12 KDa to 66 KDa. Proteins were uniformly deposited on a solid surface without pretreatment and analyzed with a DESI source coupled to a quadrupole ion trap mass spectrometer. DESI parameters optimized for protein detection included solvent flow rate, temperature of heated capillary tube, incident and reflection angle, sheath gas pressure, and ESI voltage. Detection limits were obtained for all protein standards and they were found to decrease with decreasing protein molecular weight: for cytochrome-C (12.3 KDa) and lysozyme (14.3 KDa) a detection limit of 4 ng/mm 2 was obtained; for apomyoglobin (16.9 KDa) 20 ng/mm 2 ; for β-lactoglobulin B (18.2 KDa) 50 ng/mm 2 ; and for chymotrypsinogen-A (25.6 KDa) 100 ng/mm 2 . The DESI-MS analysis of higher molecular weight proteins such as ovalbumin (44.4 KDa) and bovine serum albumin (66.4 KDa) yielded mass spectra of low signal-to-noise ratio (S/N), making their detection and molecular weight determination difficult. In this study, DESI-MS proved to be a rapid and robust method for accurate MW determination for proteins up to 17 KDa under ambient conditions. Finally, we demonstrated the DESI-MS detection of the bacteriophage MS 2 capsid protein from crude samples with minimal sample preparation.

Desorption electrospray ionization (DESI) mass spectrometry (MS) was used to differentiate seven bacteria species on the basis of their measured DESI-mass spectral profile. Both gram-positive and gram-negative bacteria were tested and included Escherichia coli, Staphyloccocus aureus, Enterococcus sp., Bordetella bronchiseptica, Bacillus thuringiensis, Bacillus subtilis and Salmonella typhimurium. Distinct DESI-mass spectra, in the mass range of 50-500 u, were obtained from whole bacteria in either positive or negative ion modes in less than 2 mins analysis time. Positive ion DESI-mass spectral fingerprints were compared using principal components analysis (PCA) to investigate reproducibility for the intraday and the day-to-day measurements and the method selectivity to differentiate the bacteria studied. Detailed study of variances in the assay revealed that a large contribution to the DESI-mass spectral fingerprint variation was the growth media preparation procedure. Specifically, experiments conducted with the growth media prepared using the same batch yielded highly reproducible DESI-mass spectra, both in intraday and in day-to-day analyses (i.e. one batch of growth media used over a 3-day period versus a new batch every day over the same 3-day period). Conclusions are drawn from our findings in terms of strategies for rapid biodetection with DESI-MS.

This study explored the effects of optimism, intrinsic motivation, and family relations on vocational identity in college students in the United States and South Korea. The results yielded support for the hypothesized multivariate model. Across both cultures, optimism was an important contributing factor to vocational identity, and intrinsic motivation partially mediated the link from optimism to vocational identity. In addition, family relations moderated the mediation effect of intrinsic motivation with American students but not Korean students. With Korean students, family relations moderated the direct link from optimism to vocational identity. These results have significant implications for counseling to promote vocational identity development for diverse college students.

The purpose of this study was to explore correlates of chronic career indecision with multivariate modeling. We examined the effects of neuroticism and negative career thoughts and feelings on lack of information, which is one of the core elements of chronic career indecision. The sample included 310 first-semester students who had entered university study without a declared academic major. The results yielded support for the hypothesized multivariate model. Negative career thoughts and feelings explained a large amount of the variance in lack of information. The influence of neuroticism on lack of information was indirect and fully mediated by negative career thoughts and feelings. These results have significant implications for counseling for chronic career indecision.

The purpose of this study was to examine resilience and decision-making strategies as predictors of difficulties experienced during the career decision-making process. College students (N = 364) responded to measures of resilience, career decisionmaking strategies, and career decision difficulties. Results indicated that resilience and decision-making strategies accounted for 46% of the variance in career decision difficulties. Resilience had a greater influence on problems encountered during decision making than on problems encountered at the outset of the process. Different decision-making strategies appeared to be related to difficulties encountered at different stages of the decision-making process. For example, aspiration for an ideal occupation was positively associated only with lack of readiness. Procrastination was the only strategy related to all three decision difficulties: lack of readiness, lack of information, and inconsistent information. The results indicated the importance of decreasing procrastination at all stages of decision making and the need to promote resilience to deal with decision difficulties.