3,305,897 research outputs found
The Mass Transportation Commission demonstration program
No full textThe Third Progress Report marks the completion of six months experiments in the program conducted by the Mass Transportation Commission, with the cooperation of the Office of Transportation of the Housing and Home Finance Agency. As of mid-June, experiments with two railroads, six bus companies and the Metropolitan Transit Author- ity were in progress. In addition, two bus experiments have been completed. This Progress Report contains considerable material which should be of wide interest to all concerned with the future of public transportation. Among the more notable items included are (a)up-to-date information on the Boston and Maine lines indicating that passenger volume has continued to increase,(b)revenue figures indicating that total fares paid by new riders have off-set the overall experimental fare reduction,(c)a survey of Boston and Maine passengers, analyzing the diversion of new passengers from highway and other forms of public transportation,(d)an analysis of the terminated Lynnfield bus experiment,and (e)parking data survey information on the MTA parking lot experiment which offer grounds for concluding that this particular experiment has resulted in substantially increased use of rapid transit facilities. In addition to presenting new material developed between mid-April and mid-June, this Report has been prepared as a self-contained, six-months' summary study incorporating much of the basic information first two Progress Reports
The Application of Mass Spectrometry in Molecular Dosimetry: Ethylene Oxide as an Example
No full textMass spectrometry plays an increasingly important role in the search for and quantification of novel chemically specific biomarkers. The revolutionary advances in mass spectrometry instrumentation and technology empower scientists to specifically analyze DNA and protein adducts, considered as molecular dosimeters, derived from reactions of a carcinogen or its active metabolites with DNA or protein. Analysis of the adducted DNA bases and proteins can elucidate the chemically reactive species of carcinogens in humans and can serve as risk-associated biomarkers for early prediction of cancer risk. In this article, we review and compare the specificity, sensitivity, resolution, and ease-of-use of mass spectrometry methods developed to analyze ethylene oxide (EO)-induced DNA and protein adducts, particularly N7-(2-hydroxyethyl)guanine (N7-HEG) and N-(2- hydroxyethyl)valine (HEV), in human samples and in animal tissues. GC/ECNCI-MS analysis after HPLC cleanup is the most sensitive method for quantification of N7-HEG, but limited by the tedious sample preparation procedures. Excellent sensitivity and specificity in analysis of N7-HEG can be achieved by LC/MS/MS analysis if the mobile phase, the inlet (split or splitless), and the collision energy are properly optimized. GC/ECNCI- HRMS and GC/ECNCI-MS/MS analysis of HEV achieves the best performance as compared with GC/ECNCI-MS and GC/EI-MS. In conclusion, future improvements in high- throughput capabilities, detection sensitivity, and resolution of mass spectrometry will attract more scientists to identify and/or quantify novel molecular dosimeters or profiles of these biomarkers in toxicological and/or epidemiological studies
Cluster secondary ion mass spectrometry microscope mode mass spectrometry imaging
No full textRATIONALE: Microscope mode imaging for secondary ion mass spectrometry is a technique with the promise of simultaneous high spatial resolution and high-speed imaging of biomolecules from complex surfaces. Technological developments such as new position-sensitive detectors, in combination with polyatomic primary ion sources, are required to exploit the full potential of microscope mode mass spectrometry imaging, i.e. to efficiently push the limits of ultra-high spatial resolution, sample throughput and sensitivity. METHODS: In this work, a C60 primary source was combined with a commercial mass microscope for microscope mode secondary ion mass spectrometry imaging. The detector setup is a pixelated detector from the Medipix/Timepix family with high-voltage post-acceleration capabilities. The system’s mass spectral and imaging performance is tested with various benchmark samples and thin tissue sections. RESULTS: The high secondary ion yield (with respect to ’traditional’ monatomic primary ion sources) of the C60 primary ion source and the increased sensitivity of the high voltage detector setup improve microscope mode secondary ion mass spectrometry imaging. The analysis time and the signal-to-noise ratio are improved compared with other microscope mode imaging systems, all at high spatial resolution. CONCLUSIONS:We have demonstrated the unique capabilities of a C60 ion microscope with a Timepix detector for high spatial resolution microscope mode secondary ion mass spectrometry imaging
Exploring Mass Message Customization
No full textThe paper begins with the exploratory concept of ‘mass customization’ and then moves on to discuss the possibility of applying it in business communication. Further, it gives a brief framework within which to fit this concept. The author then argues the relevance of the concept in today’s workplace. However, this paper does not discuss the details of the ‘process of mass message customization.’ It just hints to possible areas for further research and exploration.
Fast Mass Microscopy: Mass Spectrometry Imaging of a Gigapixel Image in 34 Minutes
No full text[Image: see text] Mass spectrometry imaging (MSI) maps the spatial distributions of chemicals on surfaces. MSI requires improvements in throughput and spatial resolution, and often one is compromised for the other. In microprobe-mode MSI, improvements in spatial resolution increase the imaging time quadratically, thus limiting the use of high spatial resolution MSI for large areas or sample cohorts and time-sensitive measurements. Here, we bypass this quadratic relationship by combining a Timepix3 detector with a continuously sampling secondary ion mass spectrometry mass microscope. By reconstructing the data into large-field mass images, this new method, fast mass microscopy, enables orders of magnitude higher throughput than conventional MSI albeit yet at lower mass resolution. We acquired submicron, gigapixel images of fingerprints and rat tissue at acquisition speeds of 600,000 and 15,500 pixels s(–1), respectively. For the first image, a comparable microprobe-mode measurement would take more than 2 months, whereas our approach took 33.3 min
PRIMARY STRUCTURE OF SUPEROXIDE DISMUTASE FROM PSEUDOALTEROMONAS HALOPLANKTIS BY A COMBINATION OF AUTOMATIC EDMAN DEGRADATION AND ESI/Q-TOF MASS SPECTROMETRY
No full textSuperoxide dismutase (SOD) is a metalloenzyme that has a protective effect against toxic superoxide radicals in both aerobic and anaerobic organisms. SODs have been classified into two families on the basis of their different structural folding and metal content (Cu/Zn in one family and Fe or Mn in the other one). SODs isolated from extremophilic organisms are suitable models to study the structure-function relationships and the molecular and evolutive mechanisms for the adaptation of proteins to extreme environments. We have previously isolated a SOD from the psychrophilic eubacterium Pseudoalteromonas haloplanktis (PhSOD), isolated from Antarctic marine sediments and adapted to grow at low temperatures. This enzyme has a specific activity of 6500 U/mg and according to preliminary characterization, PhSOD could be classified as a Fe-SOD. In this communication the rapid characterization of primary structure of PhSOD was determined using a combined approach based on automatic Edman degradatiion and electrospray ionization mass spectrometry (ESI-MS/MS). The information gathered by this approach combined with automated recording and interpretatiion of data enabled full primary structure determination of SOD with minimal time and material consumption (200 ug/10 nmoles). The primary structure of PhSOD was obtained using the following experimental steps: i) verification of the protein purity and identity by SDS-PAGE and ESI-MS; ii) enzymatic cleavage by endoproteinase Asp-N; iii) sequence determination of Asp-N peptides by Edmann degradation and iv) overlapping with tryptic peptides analysed by Q-Tof mass spectrometry and by homology with reference proteins. ESI-MS analysis of native PhSOD, obtained from RP-HPLC as the last purification step, showed that its molecular mass was 21328.50 +/- 0.40. Automated Edman degradation of peptides obtained from endoproteinase Asp-N and separated by RP-HPLC, provided most of the amino acid sequence of PhSOD. However, with this first set of data, various amino acid residues were not determined. In addition, there was the need to confirm the presence, in some positions, of seryl and threonyl residues which were obtained in low yield by automatic Edman degradation. Therefore, to complete and confirm the amino acid sequence, we decided to map the entire sequence by mass spectrometry, analysing a new set of peptides derived from trypsin hydrolysis. These peptides were separated by CapLC and analysed on-line by Q-Tof, which provided their molecular masses and the "de novo sequencing data" when it was necessary. However, the sequence of PhSOD is not complete. It remains to be assigned residue 57, which was not identified during the automatic Edman degradation. Indeed, no canonic PTH-amino acid was present. This implicates the presence of post-modification, which is likely in this class of enzymes. Future research plan includes the determination of such residue using Q-Tof mass spectrometry
High-mass-resolution MALDI mass spectrometry imaging of metabolites from formalin-fixed paraffin-embedded tissue.
No full textFormalin-fixed and paraffin-embedded (FFPE) tissue specimens are the gold standard for histological examination, and they provide valuable molecular information in tissue-based research. Metabolite assessment from archived tissue samples has not been extensively conducted because of a lack of appropriate protocols and concerns about changes in metabolite content or chemical state due to tissue processing. We present a protocol for the in situ analysis of metabolite content from FFPE samples using a high-mass-resolution matrix-assisted laser desorption/ionization fourier-transform ion cyclotron resonance mass spectrometry imaging (MALDI-FT-ICR-MSI) platform. The method involves FFPE tissue sections that undergo deparaffinization and matrix coating by 9-aminoacridine before MALDI-MSI. Using this platform, we previously detected ∼1,500 m/z species in the mass range m/z 50-1,000 in FFPE samples; the overlap compared with fresh frozen samples is 72% of m/z species, indicating that metabolites are largely conserved in FFPE tissue samples. This protocol can be reproducibly performed on FFPE tissues, including small samples such as tissue microarrays and biopsies. The procedure can be completed in a day, depending on the size of the sample measured and raster size used. Advantages of this approach include easy sample handling, reproducibility, high throughput and the ability to demonstrate molecular spatial distributions in situ. The data acquired with this protocol can be used in research and clinical practice
A micropixelated ion-imaging detector for mass resolution enhancement of a QMS instrument
No full textAn in-vacuum position-sensitive micropixelated detector (Timepix) is used to investigate the time-dependent spatial distribution of different charge state (and hence different mass-to-charge (m/z)) ions exiting an electrospray ionization (ESI)-based quadrupole mass spectrometer (QMS) instrument. Ion images obtained from the Timepix detector provide a detailed insight into the positions of stable and unstable ions of the mass peak as they exit the QMS. With the help of image processing algorithms and by selecting areas on the ion images where more stable ions impact the detector, an improvement in mass resolution by a factor of 5 was obtained for certain operating conditions. Moreover, our experimental approach of mass resolution enhancement was confirmed by in-house-developed novel QMS instrument simulation software. Utilizing the imaging-based mass resolution enhancement approach, the software predicts instrument mass resolution of ?1,0000 for a single-filter QMS instrument with a 210-mm long mass filter and a low operating frequency (880?kHz) of the radio frequency (RF) voltage
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
The encyclopedia of mass spectrometry.
No full textVolume 9: Historical Perspectives, Part A: The Development of Mass Spectrometry of The Encyclopedia of Mass Spectrometry describes and analyzes the development of many aspects of Mass Spectrometry. Beginning with the earliest types of Mass Analyzers, Historical Perspectives explores the development of many different forms of analytical processes and methods. The work follows various instruments and interfaces, to the current state of detectors and computerization. It traces the use of Mass Spectrometry across many different disciplines, including Organic Chemistry, Biochemistry, and Proteomic.Online resource; title from PDF title page (Ebsco, viewed June 19, 2015).ReferencesCurt Brunnée; References; Angus Ewan Cameron; References; Richard M. Caprioli; References; Brian T. Chait; References; Robert N. Clayton; References; Norman David Coggeshall; References; Melvin Barnet Comisarow; References; William Compston; References; R. Graham Cooks; References; Robert J. Cotter; References; Willi Dansgaard; References; Anne Dell; References; Arthur Jeffrey Dempster; References; M. Bonner Denton; References; Vernon Hamilton Dibeler; References; Carl Djerassi; References; Henry Edmison Duckworth; References; Geoffrey Eglinton; References; Christie George Enke.ReferencesSamuel Epstein; References; Heinz Ewald; References; Henry Marshall Fales; References; John Bennett Fenn; References; Catherine Clarke Fenselau; References; Frank Henry Field; References; Robert E. Finnigan; References; Russell Elwell Fox; References; Joe Louis Franklin, Jr.; References; Jean H. Futrell; References; Simon James Gaskell; References; Johannes Geiss; References; Roland S. Gohlke; References; Michael leaf Gross; References; Michael Guilhaus; References; Alexander Norman Halliday; References; Alexander George Harrison; References; John Michael Hayes; References.ReferencesChava Lifshitz; References; Frederick Pettit Lossing; References; Alexander A. Makarov; References; Boris Alexandrovich Mamyrin; References; Raymond E. March; References; Alan G. Marshall; References; Hisashi Matsuda; References; Josef Heinrich Elisabeth Mattauch; References; James A. McCloskey; References; Fred W. McLafferty; References; Seymour Meyerson; References; Fred Loomis Mohler; References; Howard Redfern Morris; References; James Douglas Morrison; References; Milam Stephen Burnaby Munson; References; Nicolaas Martinus Maria Nibbering; References; Alfred Otto Carl Nier.References.Cover; The Encyclopedia ofMass Spectrometry; Contents; Foreword; Preface to Volume 9, Part B; Introduction to Part B: Criteria for Inclusion in these Biographies of Notable People in Mass Spectrometry; References; Arthur John Ahearn; References; Claude Jean Allègre; References; Francis William Aston; References; Kenneth Tompkins Bainbridge; References; Michael Barber; References; Hans-Dieter Beckey; References; Alfred Benninghoven; References; John Herbert Beynon; References; Klaus Biemann; References; Walker Bleakney; References; John Hamilton Bowie; References; Harrison Scott Brown.William J. HenzelReferences; David Michael Hercules; References; Zdenecaronk Herman; References; Richard Franz Karl Herzog; References; Franz Hillenkamp; References; Heinrich Hintenberger; References; John Alfred Hipple, Jr.; References; John Leonard Holmes; References; Richard Edward Honig; References; Evan Charles Horning and Marjorie Groothuis Horning; References; Robert Samuel Houk; References; Donald Frederick Hunt; References; Mark G. Inghram; References; Keith R. Jennings; References; Michael Karas; References; Paul Kebarle; References; Charles Kemball; References; Frederick W. Lampe.Volume 9: Historical Perspectives, Part A: The Development of Mass Spectrometry of The Encyclopedia of Mass Spectrometry describes and analyzes the development of many aspects of Mass Spectrometry. Beginning with the earliest types of Mass Analyzers, Historical Perspectives explores the development of many different forms of analytical processes and methods. The work follows various instruments and interfaces, to the current state of detectors and computerization. It traces the use of Mass Spectrometry across many different disciplines, including Organic Chemistry, Biochemistry, and Proteomic.Elsevie
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