Halford E.,University of Oxford |
Winter B.,University of Oxford |
Mills M.D.,SAI Ltd |
Thompson S.P.,SAI Ltd |
And 6 more authors.
Rapid Communications in Mass Spectrometry | Year: 2014
RATIONALE Imaging mass spectrometry is a powerful analytical technique capable of accessing a large volume of spatially resolved, chemical data from two-dimensional samples. Probing the entire surface of a sample simultaneously requires a detector with high spatial and temporal resolutions, and the ability to observe events relating to different mass-to-charge ratios. METHODS A commercially available time-of-flight mass spectrometer, designed for matrix-assisted laser desorption/ionization (MALDI) analysis, was combined with the novel pixel imaging mass spectrometry (PImMS) camera in order to perform multi-mass, microscope-mode imaging experiments. A number of minor modifications were made to the spectrometer hardware and ion optics so that spatial imaging was achieved for a number of small molecules. RESULTS It was shown that a peak width of Δm50% < 1 m/z unit across the range 200 ≤ m/z ≤ 800 can be obtained while also achieving an optimum spatial resolution of 25 μm. It was further shown that these data were obtained simultaneously for all analytes present without the need to scan the experimental parameters. CONCLUSIONS This work demonstrates the capability of multi-mass, microscope-mode imaging to reduce the acquisition time of spatially distributed analytes such as multi-arrays or biological tissue sections. It also shows that such an instrument can be commissioned by effecting relatively minor modifications to a conventional commercial machine. Copyright © 2014 John Wiley & Sons, Ltd.
Karambakhsh A.,Islamic Azad University at Tehran |
Afshar A.,Islamic Azad University at Tehran |
Malekinejad P.,SAI Company
Journal of Materials Engineering and Performance | Year: 2012
In this research, color anodizing of Ti-6Al-4V alloy was performed in phosphoric acid solution of 0.4 M concentration and within 30 s in different voltages (10-120 V) of a DC power supply. The effect of anodizing voltages on the color and thickness of anodized layers on Ti-6Al-4V alloy surface was surveyed. Thickness and refractive index of layers were measured by spectrophotometery and reflectance curves. According to the results, thickness of layers increased with increasing anodizing voltage and was in the range of 38-167 nm. Also the refractive index of anodic film was approximately constant at about 2 and increased inconsiderably with increasing anodizing voltage. Corrosion resistance of the anodized samples in 20 and 50 V was surveyed in physiological solutions of Ringer's solution, Artificial Saliva solution, and Ringer's + 150 mM H 2O 2 solution at the temperature of 37 °C by potentiodynamic polarization method. The anodized sample in 50 V indicated lower corrosion rate than the non-anodized sample as well as the sample which was anodized in 20 V in all solutions. The non-anodized sample indicated the highest corrosion rate of about 0.25 μA cm -2. © 2010 ASM International.
Hill R.,Ford Motor Company |
Blenkinsopp P.,Ford Motor Company |
Thompson S.,SAI Ltd |
Vickerman J.,University of Manchester |
Fletcher J.S.,University of Manchester
Surface and Interface Analysis | Year: 2011
We have built a mass spectrometer which utilizes a new method of time-of-flight analysis to provide rapid data acquisition with simultaneous high spatial resolution and high mass resolution. The mass analysis is performed by sampling the secondary beam into a two-stage time-of-flight system. This removes the requirement for a pulsed primary beam as a ToF reference. No tradeoff exists between spatial and mass resolution, and acquisition speed is not limited by the primary beam duty cycle. The analyzer comprises the combination of a shaped field buncher and a nonlinear reflectron. This configuration allows the inclusion of a collision cell and an intermediate time-of-flight selection gate. So, the analyzer can operate in ms-ms mode as well as in normal time-of-flight mode. The instrument is equipped with 40 kV C60 and liquid metal cluster primary beams, which can run in d.c. mode, or, when charge neutralization is required, in slow pulsed mode. Data acquisition is continuous, eliminating loss of data during depth profiling etch cycles. The instrument has an automated sample entry system with heating to 670 K and cooling to 105 K, and includes a novel method of freeze-fracture for tissue samples or other organic samples in aqueous suspension. Copyright © 2010 John Wiley & Sons, Ltd.