Analytical Sciences » W-CAS Older News

Imaging the Structure, Symmetry, and Surface-Inhibited Rotation of Polyoxometalate Ions on Graphene Oxide

Tue, 16 Nov 2010 09:57:30 GMT

Jeremy Sloan†, Zheng Liu‡, Kazu Suenaga‡, Neil R. Wilson†, Priyanka A. Pandey†, Laura M. Perkins§, Jonathan P. Rourke, and Ian J. Shannon§ ^† Department of Physics, University of Warwick, Coventry, CV4 7AL, U.K. Nano Letters, October 26th 2010.

Atomic-resolution imaging of discrete [γ-SiW₁₀O₃₆]⁸⁻ lacunary Keggin ions dispersed onto monolayer graphene oxide (GO) films by low voltage aberration corrected transmission electron microscopy is described. Under low electron beam dose, individual anions remain stationary for long enough that a variety of projections can be observed and structural information extracted with ca. ±0.03 nm precision. Unambiguous assignment of the orientation of individual ions with respect to the point symmetry elements can be determined. The C_2v symmetry [γ-SiW₁₀O₃₆]⁸⁻ ion was imaged along its 2-fold C₂ axis or orthogonally with respect to one of two nonequivalent mirror planes (i.e., σ_v). Continued electron beam exposure of a second ion imaged orthogonal to σ_v causes it to translate and/or rotate in an inhibited fashion so that the ion can be viewed in different relative orientations. The inhibited surface motion of the anion, which is in response to H-bonding-type interactions, reveals an important new property for GO in that it demonstrably behaves as a chemically modified (i.e., rather than chemically neutral) surface in electron microscopy. This behavior indicates that GO has more in common with substrates used in imaging techniques such as atomic force microscopy and scanning tunneling microscopy, and this clearly sets it apart from other support films used in transmission electron microscopy.

Localized High Resolution Electrochemistry and Multifunctional Imaging: Scanning Electrochemical Cell Microscopy

Wed, 20 Oct 2010 09:30:55 GMT

Neil Ebejer, Mathias Schnippering, Alexander W. Colburn, Martin A. Edwards, and Patrick R. Unwin*

Department of Chemistry, University of Warwick

Analytical Chemistry, 15 October 2010

We describe highly localized electrochemical measurements and imaging using a simple, mobile theta pipet cell. Each channel (diameter <500 nm) of a tapered theta pipet is filled with electrolyte solution and a Ag/AgCl electrode, between which a bias is applied, resulting in a conductance current across a thin meniscus of solution at the end of the pipet, which is typically deployed in air or a controlled gaseous environment.

Opening of the newly built FTICR Laboratory by Professor Fred McLafferty of Cornell University

Wed, 06 Oct 2010 10:48:54 GMT

Thursday 9 September saw the official opening of the newly built Ion Cyclotron Resonance Laboratory at Millburn House, which houses state-of-the-art Fourier transform ion cyclotron resonance (FTICR) mass spectrometers.

Opening in pictures here!

Warwick Analytical Graduate School (WAGS)

Tue, 27 Jul 2010 13:32:48 GMT

Following the success of the Warwick Analytical Science Summer School in 2008, The Warwick Centre for Analytical Science will be holding a series of specialised workshops in September and November/December (information to follow at a later date) which we would like to invite you to attend. The September workshops will each be running over two days, beginning at lunch time on the first day and ending at lunch time or soon after on the second day. Lunch is provided on both days of the workshop and an evening meal will be provided on the first day. For EPSRC funded students there are free places available on the workshops and reimbursement for accommodation and daily allowance. Our speakers are renowned experts in their field and will be offering students information on cutting edge methodologies and techniques.

Web page: http://www2.warwick.ac.uk/fac/sci/wcas/wags/

Behavior of key peptide which triggers Alzheimer's disease can be detected directly

Tue, 24 Nov 2009 09:37:37 GMT

Alzheimer's Peptide Aβ1-42, an amyoid beta peptide, is found in plaques in the brains of Alzheimer's disease patients, and accumulation of this very hydrophobic peptide is thought to be the direct cause of the disease. However, the reason for accumulation is not clear. A common theory is that the balance between production and degradation of this peptide is disrupted in the disease. One method whereby degradation of the peptide can be inhibited is by modification into a form which is resistant to enzymatic degradation (proteolysis). In peptides, isomerization of aspartic acid into isoaspartic acid (where the peptide bond is via the side-chain beta carbon rather than the normal backbone alpha carbon) is known to inhibit enzymatic degradation, and may be the elusive Alzheimer's "trigger", which results in decreased degradation and therefore accumulation of the peptide. Nadia Sargaeva of Prof. Peter O'Connor's group has developed a new mass spectrometric method for detecting this isomerization and tested it out on the worst variant of the amyloid beta peptide, the full length version containing amino acids 1-42.

Read the paper

Pat Unwin's and Julie Macpherson's electrochemistry group make the cover of Chemical Communications

Mon, 16 Nov 2009 10:06:21 GMT

Ioana Dumitrescu, Patrick R. Unwin and Julie V. Macpherson make the cover of Chem.Commun with their feature article on Electrochemistry at carbon nanotubes (CNTs): It is a large and growing field, but one in which there is still uncertainty about the fundamental activity of CNTs as electrode materials. On the one hand, there are many reports which focus on the favourable electrochemical properties of CNT electrodes, such as enhanced detection sensitivity, electrocatalytic effects and reduced fouling. On the other hand, other studies suggest that CNTs may be no more electroactive than graphitic powder. Furthermore, it has been proposed that the catalytic nanoparticles from which CNTs are formed may dominate the electrochemical characteristics in some instances. A considerable body of the literature presumes that the CNT sidewall is inert and that edge-plane-graphite-like open ends and defect sites are responsible for the electron transfer activity observed. In contrast, studies of well characterised single-walled nanotube (SWNT) electrodes, either as individual tubes or as two-dimensional networks, suggest sidewall activity. This review highlights how the various discrepancies in CNT electrochemistry may have arisen, by taking a historical view of the field and identifying crucial issues that still need to be solved. When assessing the behaviour of CNT electrodes, it is vitally important that careful consideration is given to the type of CNT used (SWNT or multi-walled), the quality of the material (presence of impurities), the effect of chemical processing steps in the fabrication of electrodes and the experimental arrangements adopted. Understanding these key features is an essential requirement to develop a fundamental understanding of CNT electrochemistry, to allow a wide range of electroanalytical applications, and to move the field forward rationally. As part of this process, high resolution electrochemical and electrical imaging techniques are expected to play a significant role in the future, as well as theoretical developments which examine the fundamentals of electron transfer at different types of CNTs and their characteristic surface sites. http://dx.doi.org/10.1039/b909734a

12 Tesla Magnet Installation in pictures!

Thu, 03 Sep 2009 12:15:01 GMT

Annals of Applied Statistics accept Dr Fabio Rigat's manuscript on "Semi-parametric dynamic time series modelling with applications to detecting neural dynamics" for publication

Thu, 20 Aug 2009 08:09:28 GMT

The Annals of Applied Statistics , one of the top international journals on the interface of methodological and applied statistics (impact factor 2.448) has recently accepted for publication the manuscript "Semi-parametric dynamic time series modelling with applications to detecting neural dynamics" , by Fabio Rigat and Jim Q.Smith. This paper proposes novel methodology for modeling of streams of experimental data when the dynamics of the systems being studied are not well understood. Several applications are illustrated using neural data, comprising non-invasive electroencephalograms (EEG) recordings, behavioural experiments and in-vivo multiple spike train recordings.

Peter O'Connor Group constructing 12T ESI FTICR mass spectrometer

Wed, 19 Aug 2009 14:17:10 GMT

The lab is currently building a 12 Tesla FTICR mass spectrometrer with the following features.

1. Electrospray ion source.

2. Focusing quadrupole (Q0) and mass filtering quadrupole (Q1)

3. Hexapole collision cell with linac extraction electrodes.

4. Currently a transfer hexapole (H1) is incorporated, but this will be changed to a turning quadrupole in the near future. See below.

5. A thin gate valve.

6. A long transfer hexapole. This may be changed to a sectioned hexapole for decreased time-of-flight lag effects.

7. A shimmed, capacitively coupled open cylindrical ICR cell.

In the near future, several modifications are very likely.

1. The transfer hexapole (H1) will be replaced with a couple of hexapoles and a turning quadrupole.

2. The ESI source will be mounted at 90 degrees from the current arrangement.

3. One or more other chambers will be added. In the case below, a MS/MS chamber for MAF, PD, or ETD is included, but it could also be a MALDI source if one is deemed necessary.

Key role for Professor Peter O'Connor (WCAS) in Chemistry Department collaboration with Bruker developing extreme performance mass spectrometry

Tue, 18 Aug 2009 14:24:57 GMT

COVENTRY, United Kingdom--(BUSINESS WIRE)--Bruker Daltonics announced today the establishment of a long-term collaborative programme for developing both applications and fundamental instrument technology in the area of extreme resolution mass spectrometry.

Building on over 14 years of experience in high performance mass spectrometry at the Department of Chemistry at Warwick, the University’s recent acquisition of both the new Bruker solariX™ 12 Tesla FTMS system and the maXis™ UHR-TOF system again puts the department at the forefront of technology for high performance mass spectrometry. At the core of the new instruments are dramatic improvements, up to an order of magnitude, in previous performance standards. These advances help address the University’s most challenging analyses including very complex mixtures in applications such as chemistry, medicinal discovery, protein interactions and petroleomics.

The collaboration is unusual in that it embraces not only topical applications innovation but also fundamental instrument development, the latter headed by Warwick Professor Peter O’Connor, who recently arrived from Boston University, and is one of the world’s most accomplished FTMS instrument development scientists. “We are very excited to be able to benefit from Peter’s ideas, and have arranged a technical fast-track for his developments to appear in our FTMS products,” commented Dr. Michael Schubert, Executive Vice President for R&D at Bruker Daltonics.

Professor Peter Sadler, Head of Chemistry at the University, whose research interests focus on metals in biology and medicine, the design and mechanism of action of metallodrugs, especially the role of proteins in metal-induced signal transduction said: “In my field state-of-the-art analysis of metal speciation holds the key to major breakthroughs in understanding both how metal ions control natural biological processes, and how metal complexes can be designed as novel therapeutic agents. Moreover, this new Bruker mass spec equipment, and the associated collaboration, will allow our newly established EPSRC Warwick Centre for Analytical Science to compete strongly at the forefront of the field.”

“We are delighted that Professors Sadler and O’Connor, who both have outstanding track records in the design and implementation of cutting-edge mass spectrometry, have chosen Bruker as a supplier and collaborative partner. It is especially gratifying to see real instrument development receiving such an energetic renewal in the UK,” commented Dr. Ian Sanders, Executive Vice President for Worldwide Sales and Marketing at Bruker Daltonics.

The solariX and maXis will be highlighted at the 18^th International Mass Spectrometry Conference (www.imsc-bremen-2009.de) in Bremen, Germany from August 30 to September 4, 2009. For more information on IMSC 2009 and related Bruker Daltonics activities, please visit www.bdal.com/imsc.

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