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A fast and sensitive direct extraction (DE) method developed in our group can efficiently extract proteins in 30 min from a 5 cm-long hair strand. Previously, we coupled DE to downstream analysis using gel electrophoresis followed by in-gel digestion, which can be time-consuming. In searching for a better alternative, we found that a combination of DE with a bead-based method (SP3) can lead to significant improvements in protein discovery in human hair. Since SP3 is designed for general applications, we optimized it to process hair proteins following DE and compared it to several other in-solution digestion methods. Of particular concern are genetically variant peptides (GVPs), which can be used for human identification in forensic analysis. Here, we demonstrated improved GVP discovery with the DE and SP3 workflow, which was 3 times faster than the previous in-gel digestion method and required significantly less instrument time depending on the number of gel slices processed. Additionally, it led to an increased number of identified proteins and GVPs. Among the tested in-solution digestion methods, DE combined with SP3 showed the highest sequence coverage, with higher abundances of the identified peptides. This provides a significantly enhanced means for identifying proteins and GVPs in human hair.

The performance of three algorithms for predicting nominal molecular mass from an analyte’s electron ionization mass spectrum is presented. The Peak Interpretation Method (PIM) attempts to quantify the likelihood that a molecular ion peak is contained in the mass spectrum, whereas the Simple Search Hitlist Method (SS-HM) and iterative Hybrid Search Hitlist Method (iHS-HM) leverage results from mass spectral library searching. These predictions can be employed in combination (recommended) or independently. The methods were tested on two sets of query mass spectra searched against libraries that did not contain the reference mass spectra of the same compounds: 19,074 spectra of various organic molecules searched against the NIST17 mass spectral library and 162 spectra of small molecule drugs searched against SWGDRUG version 3.3. Individually, each molecular mass prediction method had computed precisions (the fraction of positive predictions that were correct) of 91, 89, and 74%, respectively. The methods become more valuable when predictions are taken together. When all three predictions were identical, which occurred in 33% of the test cases, the predicted molecular mass was almost always correct (>99%).

This work presents methods for identifying and then creating a mass spectral library for disulfide-linked peptides originating from the NISTmAb, a reference material of the humanized IgG1k monoclonal antibody (RM 8671). Analyses involved both partially reduced and non-reduced samples under neutral and weakly basic conditions followed by nanoflow liquid chromatography tandem mass spectrometry (LC–MS/MS). Spectra of peptides containing disulfide bonds are identified by both MS1 ion and MS2 fragment ion data in order to completely map all the disulfide linkages in the NISTmAb. This led to the detection of 383 distinct disulfide-linked peptide ions, arising from fully tryptic cleavage, missed cleavage, irregular cleavage, complex Met/Trp oxidation mixtures, and metal adducts. Fragmentation features of disulfide bonds under low-energy collision dissociation were examined. These include (1) peptide bond cleavage leaving disulfide bonds intact; (2) disulfide bond cleavage, often leading to extensive fragmentation; and (3) double cleavage products resulting from breakages of two peptide bonds or both peptide and disulfide bonds. Automated annotation of various complex MS/MS fragments enabled the identification of disulfide-linked peptides with high confidence. Peptides containing each of the nine native disulfide bonds were identified along with 86 additional disulfide linkages arising from disulfide bond shuffling. The presence of shuffled disulfides was nearly completely abrogated by refining digest conditions. A curated spectral library of 702 disulfide-linked peptide spectra was created from this analysis and is publicly available for free download. Since all IgG1 antibodies have the same constant regions, the resulting library can be used as a tool for facile identification of “hard-to-find” disulfide-bonded peptides. Moreover, we show that one may identify such peptides originating from IgG1 proteins in human serum, thereby serving as a means of monitoring the completeness of protein reduction in proteomics studies. Data are available via ProteomeXchange with identifier PXD023358.

It is frequently recounted that shortly before Michelangelo died, the eighty-eight-year-old artist sat before a fire and burned many drawings. Critical examination reveals various motivations for such a destructive act and elicits suggestions for what Michelangelo might have burned. Mainly because of old age and significant changes in his artistic practice, Michelangelo made far fewer drawings in his final two decades than earlier in his career. Therefore, he may have destroyed less than is usually imagined and nothing that would have impaired the completion of his current projects, most important of which was New Saint Peter’s.

We describe the creation of a mass spectral library of acylcarnitines and conjugated acylcarnitines from the LC–MS/MS analysis of six NIST urine reference materials. To recognize acylcarnitines, we conducted in-depth analyses of fragmentation patterns of acylcarnitines and developed a set of rules, derived from spectra in the NIST17 Tandem MS Library and those identified in urine, using the newly developed hybrid search method. Acylcarnitine tandem spectra were annotated with fragments from carnitine and acyl moieties as well as neutral loss peaks from precursors. Consensus spectra were derived from spectra having similar retention time, fragmentation pattern, and the same precursor m/zand collision energy. The library contains 157 different precursor masses, 586 unique acylcarnitines, and 4 332 acylcarnitine consensus spectra. Furthermore, from spectra that partially satisfied the fragmentation rules of acylcarnitines, we identified 125 conjugated acylcarnitines represented by 987 consensus spectra, which appear to originate from Phase II biotransformation reactions. To our knowledge, this is the first report of conjugated acylcarnitines. The mass spectra provided by this work may be useful for clinical screening of acylcarnitines as well as for studying relationships among fragmentation patterns, collision energies, structures, and retention times of acylcarnitines. Further, these methods are extensible to other classes of metabolites.

We describe a patient who presented with a history of unexplained exertional dyspnea and pulmonary infiltrates. She was evaluated for interstitial lung disease, presumed to be idiopathic and underwent an [...]

The article explores various aspects of a drawing found on the back of a drawn portrait of the Egyptian ruler Cleopatra, by the Italian Renaissance artist Michelangelo. Particular focus is given to speculations that the drawing was completed by the artist Tommaso de' Cavalieri, a friend and admirer of Michelangelo. The exhibition "Michelangelo: Sacred and Profane, Master Drawings from the Casa Buonarroti," to be held at the Museum of Fine Arts, Boston from April 21st through June 30, 2013 is also discussed.

3‐Methacryloxypropyltrimethoxysilane (MPTMS) was converted to silsesquioxane oligomers by hydrolysis/condensation in three dental monomer solutions. The molecular mass distribution and molecular structures of these oligomers was studied by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry. Each dental monomer imparted distinct characteristics on the oligomeric silsesquioxane produced. Ethoxylated bisphenol A dimethacrylate (EBPADMA) produced low‐mass oligomer silsesquioxanes that showed complete hydrolysis and a very high degree of intramolecular condensation (i.e., there were no methoxy and few silanol groups remaining on the oligomers). 1,6‐Bis(methacryloxy‐2‐ethoxycarbonylamino) 2,4,4‐trimethylhexane also produced fully hydrolyzed oligomeric silsesquioxanes but with twice the average molecular mass as the EBPADMA. Finally, triethylene glycol dimethacrylate produced higher mass oligomeric silsesquioxanes than EBPADMA even though it showed incomplete hydrolysis. The degree of hydrolysis increased with increasing mass, as did the degree of intramolecular condensation. Oligomers with degrees of polymerization below 8 were poorly hydrolyzed and showed little if any intramolecular condensation. Those with degrees of polymerization of 9 or greater were almost completely hydrolyzed with a high level of intramolecular condensation. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1842–1847, 2006

Electrospray ionization Fourier transform ion cyclotron resonance (ESI-FTICR) mass spectrometry and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry were applied to a complex silsesquioxane-siloxane copolymer resin. The wide-polydispersity starting material was fractionated into 21 separate fractions in order to facilitate the analysis by mass spectrometry. ESI-FTICR exact mass measurements were able to identify the specific oligomers present in the lowest mass fractions and showed that very few unreacted silanol groups remained, that is, topologically closed structures predominated. MALDI-TOFMS was able to show that gel-permeation chromatography substantially underestimated the molecular masses of the higher mass fractions. Mass autocorrelation was able to show that the silsesquioxane monomer appeared only in even numbers in any given oligomer. This is a natural consequence of the highly condensed nature of the resin. Copyright © 2001 John Wiley & Sons, Ltd.

Polyethylene’s inert nature and difficulty to dissolve in conventional solvents at room temperature present special problems for sample preparation and ionization in mass spectrometric analysis. We present a study of ionization behavior of several polyethylene samples with molecular masses up to 4000 Da in laser desorption ionization (LDI) time-of-flight mass spectrometers equipped with a 337 run laser beam. We demonstrate unequivocally that silver or copper ion attachment to saturated polyethylene can occur in the gas phase during the UV LDI process. In LDI spectra of polyethylene with molecular masses above ~1000 Da, low mass ions corresponding to metal—alkene structures are observed in addition to the principal distribution. By interrogating a well-characterized polyethylene sample and a long chain alkane, C94H190, these low mass ions are determined to be the fragmentation products of the intact metal—polyethylene adduct ions. It is further illustrated that fragmentation can be reduced by adding matrix molecules to the sample preparation.

New dielectric films are prepared by both pyrolytic and photolytic conversion of β-chloroethyl-silsesquioxane (BCESSQ). Film thickness, refractive index, composition, density and morphology are characterized using a palette of techniques including ellipsometry, Rutherford backscattering and forward recoil spectrometry, X-ray reflectivity, and atomic force and electron microscopies. After annealing at 350°C, BCESSQ films, initially 200 nm thick reach about 55% of their original thickness after 20 min. For films heated in air for 4 h, the atom fractions of carbon and hydrogen monotonically decrease to 10 and 30%, respectively, as annealing temperature increases from 225 to 450°C. The BCESSQ reactivity is reflected in the loss of chlorine at 400°C. At 450°C, the film density is 1.88 g/cm3, or 84% of thermally-grown silicon oxide. Upon exposure to ultraviolet ozone radiation, films ranging from ca. 200 to 700 nm are found to convert to ormosil films within 30 min. Surprisingly, the chlorine concentration is found to decrease more quickly than the hydrogen and carbon concentrations, suggesting that the ormosil film evolves HCl leaving a vinyl group of SiCHCH2. This reaction pathway differs from the thermal case. For films prepared by pyrolytic and photolytic methods, atomic force and electron microscopy studies show that the surface is smooth and featureless, the bulk is void free when view at a magnification of 50 000×, and the ormosil/substrate interface is continuous.

This article relates the history of a little known Michelangelo project for a reliquary tabernacle in the church of San Silvestro in Capite, Rome. A primary object of the essay is to explain the social dynamics contained in this history and to reveal the interplay of personal, political, and professional relations that are involved even in a minor undertaking by a major artist. Particularly important is the cast of characters involved and the blurring of the boundaries of patronage, favor, and friendship. Ultimately the project is interesting for the view it provides of Michelangelo in a dense web of social relations at an unusually busy moment in the artist's career.

The Risen Christ by Michelangelo in the church of Santa Maria sopra Minerva in Rome is one of the artist's least admired works. While modern observers frequently have found fault with the statue, it satisfied its patrons enormously and was widely admired by contemporaries. Not least, the sculpture has suffered from the manner in which it is presently displayed and from biased photographic reproduction that emphasizes unfavorable and inappropriate views of Christ. In this paper, I examine the Risen Christ afresh by restoring it to its original context and discussing its unusual and moving iconography. Thus, it is possible to comprehend the effect of the Christ as a devotional object, to appreciate its success as a work of art, and to account for some of the modern distaste.

A method has been developed to characterize large populations of individual respirable particles. With the use of custom data collection and data correlation computer software, the same set of particles can be analyzed in multiple instruments. The method is demonstrated by the analysis of a sample of hard‐metal particles. A series of particles are analyzed by Auger electron spectroscopy, and then the same particles are analyzed by scanning electron microscopy‐energy dispersive spectroscopy.

The author suggests that the marble busts "Lachesis" and "Atropos" were made by Florentine sculptor/architect Francesco da Sangallo, assistant and close associate of Michelangelo. He explains that the design of the marble busts are Michelangelesque in character. He examines other works by da Sangallo including the tomb of Bishop Angelo Marzi in SS. Annunziata, Florence, Italy. He emphasizes the significance of the extreme realism of the sculptor's style to Renaissance art.

In this article, the author argues that the Italian Renaissance sculptor Michelangelo Buonarroti deliberately made his statue of "David" too heavy to be lifted to its intended location on a buttress of the Florence Cathedral. In addition, the author suggests that the realization that the nude sculpture could not be placed on the cathedral gave Michelangelo the freedom to carve a wholly original work that launched his career as a successful artist.

Highlights the existence of discoveries proclaiming to be those of Michelangelo. Varieties of findings; Situation with Michelangelo's paintings and works; Demographics of situation.

Describes the painting `Venus and the Organ Player,' featured at the Titian exhibition in Venice in 1990. Apparition-like quality of the scene showing a well-dressed man pausing in the midst of playing an instrument to stare at the private parts of a goddess; Suspension between sound and silence, the visible and invisible; Symbolism of the dog in the painting; Meaning of the painting.