Cognition

To the worth of all seas

2009-12-22T07:22:00.001+03:30

My precious Oxford
To the worth of all seas

THz technique

2009-12-20T05:43:00.004+03:30

THz frequencies are employed for interrogation at nanoscale, for their key energy and timescales, since electrons dynamics in nanostructures fall in THz frequency region. Photonics are key players for development of THz devices such as quantum cascade laser QCL or THz single photon detector.

Oxford Terahertz Photonics group
http://www-thz.physics.ox.ac.uk/spectrometer/References.html
- Cutting-edge terahertz technology, M Tonouchi, Nat. Photon., 1:97-105 (2007)
- Terahertz pulse imaging in reflection geometry of human skin cancer and skin tissue, RM Woodward, BE Cole, VP Wallace, RJ Pye, DD Arnone, EH Linfield, M Pepper Phys. Med. Biol., 47:3853 (2002)
- Thz-wave spectroscopy applied to the detection of illicit drugs in mail, A Dobroiu, Y Sasaki, T Shibuya, C Otani, K Kawase Proc. IEEE, 95:1566 (2007)

Oxford University is also home to two Interdisciplinary Research Collaboration (IRC) centres - Quantum Information Processing (QIP) and Bio-nanotechnology. QIP is a cross-disciplinary team working with industry to harness the latest developments in this field so as to manipulate, store and communicate information. The Bio-nanotechnology IRC investigates naturally occurring biomolecular nanosystems and applies this knowledge to produce artificial electronic and optical devices.
Begbroke Science Park: http://www.begbroke.ox.ac.uk/research/nanotechnology.php

THz Technique

Time domain THz technique can probe the properties of charge carriers, contacts, defects, scattering events and other phenomena in carbon nanotubes and related nanoscale materials and devices, with sub-picosecond resolution.

This schematic diagram shows some of the phenomena that can be explored: (clockwise from top left) electron–electron scattering; electron–phonon scattering; the role of structural defects; and the relative importance of single-electron and plasmon excitation. A carbon nanotube FET is also shown.

Bradley F. Habenicht & Oleg V. Prezhdo, Nanotube devices: Watching electrons in real time, Nature Nanotechnology 3, 190 - 191 (2008) Published online: 23 March 2008

Seasons Greeting

2009-12-17T07:08:00.002+03:30

http://www.sbs.ox.ac.uk/seasonsgreetings/default.htm

Oxford's BegBroke Science Park

2009-12-08T06:30:00.003+03:30

Begbroke Science Park Clean Room - Oxford

Hydrodynamic Voltammetry

The transport-limited current at microchannel electrodes may be quantitatively predicted by using the hopscotch algorithm to solve the mass-transport equation descibing the transport of electroactive material by convection and diffusion in a direction both axial and normal to the electrode surface. In particular, axial diffusion effects are found to be substantial for electrodes of micrometer dimensions in length, and the result of such effects is to propagate concentration depletion effects dramatically upstream of the electrode. The theoretical predictions were found to be in quantitative agreement with experiment.

Peter Dobson, Hydrodynamic Voltammetry with Microelectrodes. Channel Microband Electrodes: Theory and Experiment, J. Phys. Chem. 1993,97, 10410-10415

Si NanoWire Biosensor

2009-11-30T04:43:00.005+03:30

Silicon nanowire SiNW FETs could be used to detect binding and unbinding of proteins to their corresponding ligands linked to nanowire surfaces in aqueous solutions. Proteins and nucleic acids also have been detected by using carbon nanotubes and SiNW FETs, respectively.

fig 1 - Detection of ATP binding. (A) Conductance (G) vs. ATP concentration for SiNWs modified with Abl (red curve) and a device prepared in an identical fashion, except Abl was not coupled to the surface (black curve). Regions 1, 2, and 3 correspond to 0.1, 3, and 20 nM ATP, respectively. Arrows indicate the points where solution is changed. (Inset) Scanning electron micrograph of a typical SiNW FET device. The nanowire is highlighted by a white arrow and is contacted on either end with Ti/Au metal electrodes. (Scale bar: 500 nm.) (B) Change in conductance (ΔG) vs. ATP concentration for Abl-modified SiNW (red) and SiNW without Abl (black).

ATP Sensing. Typical time-dependent data recorded from an Abl-modified SiNW device (Fig. 1) exhibited reversible, concentration-dependent increases in conductance upon introducing buffer solutions containing ATP. The reversibility of these concentration-dependent increases was evident from the corresponding decreases in conductance to baseline value upon introducing buffer solution without ATP. The observed increases in conductance are consistent with the binding of negatively charged ATP to Abl. Specifically, a p-type SiNW FET will exhibit an increase (decrease) in conductance when the gate-voltage is negative (positive) because of the accumulation (depletion) of carriers. Binding of negatively charged ATP to the Abl kinase increases the negative surface-charge density and increases conductance similar to a negative gate voltage.

Wang U W et al, Label-free detection of small-molecule–protein interactions by using nanowire nanosensors, PNAS March 1, 2005 vol. 102 no. 9 3208-3212

Fig 2-Nanowire with excitation at the bottom end and top end (no plasmon excitement)

Nanowire Nanosensors for Highly Sensitive and Selective Detection of Biological and Chemical Species

fig 3- NW nanosensor for pH detection. (A) Schematic illustrating the conversion of a NW FET (field effect transistor) into NW nanosensors for pH sensing. The NW is contacted with two electrodes, a source (S) and drain (D), for measuring conductance. Zoom of the APTES-modified SiNW surface illustrating changes in the surface charge state with pH. (B) Real-time detection of the conductance for an APTES-modified SiNW for pHs from 2 to 9; the pH values are indicated on the conductance plot. (inset, top) Plot of the time-dependent conductance of a SiNW FET as a function of the back-gate voltage. (inset, bottom) Field-emission scanning electron microscopy image of a typical SiNW device. (C) Plot of the conductance versus pH; the red points (error bars equal ± 1 SD) are experimental data, and the dashed green line is linear fit through this data. (D) The conductance of unmodified SiNW (red) versus pH. The dashed green curve is a plot of the surface charge density for silica as a function of pH.

networks of protein interactions

2009-11-30T04:30:00.002+03:30

Systems Biology and New Technologies Enable Predictive and Preventative Medicine

A network perturbation model of galactose utilization in yeast. This model reflects the integration of mRNA levels for the 6000 yeast genes in each of 20 different genetic and environmental perturbations, as well as thousands of protein/protein and protein/DNA interactions from the literature. The software program Cytoscape (54) integrated these data into a network where the nodes represent proteins (encoded by genes) and the lines represent interactions (blue straight lines, protein/protein interactions; yellow lines with arrows, protein/DNA interactions). A gray scale represents the levels of mRNA, with black being abundant levels and white very low levels. The red node indicates that this network model reflects the knockout of the corresponding gene (and protein) gal 4—a key transcription factor. rProtein, ribosomal protein; nt, nucleotide; synth, synthesis.

Hood et al, Science 22 October 2004: Vol. 306. no. 5696, pp. 640 - 643

Oxford's Begbroke science park

2009-11-29T20:59:00.003+03:30

"We must improve at translating good ideas into commercial success."
(Sir Digby-Jones, Director-General of the CBI)

When the size of the structure is decreased, surface to volume ratio increases considerably and the surface phenomena predominate over the chemistry and physics in the bulk (Sammy)

Innovation is key to meeting many of today’s development challenges, and the primary force for innovation is fundamental research. Without it, there would be no science to apply. Faraday's experiments on electricity, for example, were driven by curiosity but eventually brought us electric light. No amount of R&D on the candle could ever have done that. Electric light came from innovation driven by fundamental science.

Faith of Silica nanoparticles in wastewater treatment

2009-11-14T22:21:00.005+03:30

Fate of Silica Nanoparticles in Simulated Primary Wastewater Treatment

Peter Dobson et al, Environ. Sci. Technol., 2009, 43 (22) pp 8622-8628

Through novel application of small-angle neutron scattering, we examined the fate of silica nanoparticles (SiO2NPs) during simulated primary wastewater treatment, by measuring, in real time, the colloidal behavior of SiO2NPs in wastewater (sewage). We examined the effects of surface functionality on SiO2NP fate in wastewater, by comparing both unfunctionalized (uncoated or “bare”) SiO2NPs and SiO2NPs functionalized with a thin coating of a nonionic surfactant (Tween 20), which is widely used in personal care and household product formulations containing engineered oxide nanoparticles. Our results show new evidence that the surface functionality of SiO2NPs plays a crucial role in their flocculation and sedimentation behavior in wastewater, and thus the likely efficacy of their removal from the effluent stream during primary wastewater treatment. Uncoated SiO2NPs did not flocculate in wastewater over typical residence times for primary treatment. Conversely, surface-functionalized (Tween-coated) SiO2NPs underwent rapid flocculation in wastewater. Our results show that the surface-functionalized SiO2NPs are likely to be removed by sedimentation to sewage sludge (typically recycled to land), whereas uncoated SiO2NPs will continue through the effluent stream. While nanoparticle design is driven by use purpose, this study shows new potential for exploiting surface functionalization of nanoparticles to modify their environmental pathways.

http://www.isis.stfc.ac.uk/science/earth-science-and-environment/managing-nanoparticle-waste-in-sewage9094.html
http://pubs.acs.org/doi/abs/10.1021/es901399q
http://www.nerc.ac.uk/research/programmes/nanoscience/

How do model hydrophobic polymers respond to interfaces having a range of chemistries from hydrophobic to hydrophilic?
To what surfaces do such polymers “stick”, and what is the magnitude of the binding free energy?
What conformational changes occur upon adsorption onto different surfaces?
How different are the dynamics at the interface, and to what extent are they influenced by the interfacial chemistry?

Water-mediated interactions drive the polymer to adsorb strongly at a hydrophobic interface and repel it from hydrophilic ones. At hydrophilic surfaces, van der Waals interactions between the polymer and the surface mitigate this water-mediated repulsion, leading to weak adsorption of the polymer. Although the polymer is strongly adsorbed to hydrophobic surfaces, it is also most dynamic there. Translational diffusion and conformational dynamics are faster at hydrophobic surfaces compared to those at hydrophilic ones.

Unwanted adsorption is a significant problem in a range of applications from separation processes (e.g.,membrane fouling6) tomarine coatings (7-10) to implants.(1,2) Alternatively, one may be interested in controlling and engineering binding in a specific manner leading to an alignment of molecules or pattern formation with applications in sensing and detection.(3-6)

The thermodynamics of adsorption are then governed by the interplay of intermolecular interactions between them. In aqueous systems, the structural organization of water molecules near a given surface and a solute induces water-mediated interactions between them.17 These water-induced interactions contribute in
addition to the direct surface-solute interactions and can be attractive (e.g., hydrophobic) or repulsive depending on the chemistry and the nature of the surface and the solute. In situations where the solute molecule is conformationally flexible,
additional important questions arise regarding preferred conformations in the adsorbed state and the dynamics of conformational transitions at the interface.

How Surface Wettability Affects the Binding, Folding, and Dynamics of
Hydrophobic Polymers at Interfaces, Langmuir article, Received April 3, 2009. Revised Manuscript Received April 27, 2009
pubs.acs.org/Langmuir
(1) Pavithra, D.; Doble, M. Biomed. Mater. 2008, 3.
(2) Wisniewski, N.; Reichert, M. Colloids Surf., B 2000, 18, 197–219.
(3) Hayden, O.; Lieberzeit, P. A.; Blaas, D.; Dickert, F. L. Adv. Funct. Mater.
2006, 16, 1269–1278.
(4) Choi, I.; Kang, S. K.; Lee, J.; Kim, Y.; Yi, J. Biomaterials 2006, 27, 4655–
4660.
(5) Mrksich, M.; Dike, L. E.; Tien, J.; Ingber, D. E.; Whitesides, G. M. Exp.
Cell Res. 1997, 235, 305–313.
(6) Shi, H. Q.; Tsai, W. B.; Garrison, M. D.; Ferrari, S.; Ratner, B. D. Nature
1999, 398, 593–597.
(7) Dobretsov, S.; Dahms, H. U.; Qian, P. Y. Biofouling 2006, 22, 43–54.
(8) Genzer, J.; Efimenko, K. Biofouling 2006, 22, 339–360.
(9) Yebra, D. M.; Kiil, S.; Dam-Johansen, K. Prog. Org. Coat. 2004, 50, 75–104.
(10) Schmidt, D. L.; Brady, R. F.; Lam, K.; Schmidt, D. C.; Chaudhury, M. K.
Langmuir 2004, 20, 2830–2836.

Static ion mass spectrometry of adsorbed protein, Anal. Chem. 1003, 65, 1431-1430

Static secondary ion mass spectrometry (SIMS) was used to analyze proteins adsorbed to biomaterial surfaces. A spectral interpretation protocol was established by examining homopolymers of 16 amino acids. This protocol allows for the assignment of peaks unique to the various amino acids. Static SIMS was used to analyze plasma proteins adsorbed to titanium. The various factors that contributed to the relative intensities observed in the spectra were explored.

Proteins are composed of 20 amino acids. The molar 5% C, 0, and N in most proteins is remarkably constant. Proteins, except for a few specific structural proteins, have
similar amino acid contents. In a study comparing the frequency of occurrence of each amino acid residue in the primary structure of 207 unrelated proteins, the number of times an amino acid is observed in a randomly chosen portion of the molecule is related only to its frequency; that is, proteins do not exhibit characteristic sequences at the local leve1. However, a concern for specific higher order distributions (apolar, polar, charged, etc.) is expressed, because such
distributions lead to specific chain folding and protein c~nformation.I~t ~i s manifestations of this higher order distribution, related to protein orientation and conformation at surfaces, that is of interest in the biological reaction of proteins at interfaces. This study provides some of the groundwork needed to explore amino acid distributions within the outermost 20 A of a protein layer.

33) Paynter, R. W.; Ratner, B. D. In Surface and Interfacial Aspects
of Biomedical Polymers; Andrade, J. D., Ed.; Plenum: New York, 1985;
(34) Klapper, M. H. Biochem. Biophys. Res. Commun. 1977,78,1018 -1024

New Normal

2009-11-13T01:42:00.000+03:30

"The UK as a whole has four of the world's top six universities, and they typically spin out around 200 companies a year. Whilst London is best defined as a global talent hub, it can also be described as the world's largest science park, with financial and legal advice close at hand."

(Baroness Valentine, in the occasion of the Nanotechnology Knowledge Transfer Network (NanoKTN) and UK Trade & Investment (UKTI) in the London Hilton Park Lane, Nov 2009)

The gloomy time will pass, and good times will come back. This much is certain, when we finally enter the post crisis period, the business and economic context will not have returned to pre crisis context. The New Normal business scene will have changed. The result will be an environment that while different from the past, is no less rich in possibilities for those who are intelligently prepared. (Ian Davis)

Invent the future

2009-10-13T02:42:00.000+03:30

The best way to predict the future is to invent it.

Alan Kay (1940– ), American computer scientist

cited in www.askoxford.com

Four generations of nanotechnology products: Roco

2009-10-04T15:48:00.001+03:30

Four generations of nanotechnology products and their respective manufacturing methods and research foci are identified: Passive nanostructures; active nanostructures; three-dimensional (3-D) nanosystems and systems of nanosystems; and heterogeneous molecular nanosystems. Designing new atomic and molecular assemblies is expected to increase in
importance, including macromolecules “by design” nanoscale machines, and directed multiscale selfassembling. Although expectations from nanotechnology may be overestimated in short-term, the long-term implications on healthcare, productivity
and environment appear to be underestimated.

http://www.nsf.gov/crssprgm/nano/reports/mcr_04-0101_visionnt@aiche_final.pdf

Knowledge Transfer Partnership KTP

2009-10-04T14:45:00.004+03:30

Oxford University's Knowledge Transfer Partnership (KTP) office initiates and supports the University's KT partnerships between academics, companies and high-calibre graduates seeking to make an impact in the business environment. It enables companies to access the University's research expertise and facilities, academics to apply their knowledge to developing solutions to real-world problems and graduates to develop their business skills in tandem with involvement in hi-tech research at the University.

Knowledge Transfer Partnerships are part-funded by the Government, which reimburses a proportion of the University's costs. The company pays the rest - typically, for an SME, one third of the cost of the project plus its own business overheads.

For more details of the KTP scheme visit contact us at ktp@begbroke.ox.ac.uk, download our handout summarising the benefits of KTPs to each of the partners, or visit the schemes national websites at www.dti.gov.uk/ktp | www.ktponline.co.uk/

SAFENANO INITIATIVES:

Our most notable development being launch of a new 'Projects mini-section' of the
SAFENANO site, which details all of our past and ongoing projects, and provides access to many of the full reports which were produced as aresult of these. We'd appreciate your feedback on the information included in this section, so follow this link to have a look , and let us know your thoughts via our contact us link!

Elsewhere the fields of regulation, guidance and standards have seen a number of new developments emerge in the last week. This has been particularly true within the US, where the ASTM announced revision of its nanotechnology standard E2490 'Guide for Measurement of Particle Size Distribution of Nanomaterials in Suspension by Photon Correlation Spectroscopy' following conduction of a large-scale inter-laboratory
study, and the EPA also released a draft for consideration of 'Nanomaterial Case Studies: Titanium Dioxide'. This document aims to take a comprehensive environmental assessment (CEA) approach to evaluating NPs in products, which combines a product life-cycle framework with the risk assessment paradigm (the applications included
in the case study being sunscreen and water treatment). Overall, it provides both a source of information for interested parties, and an insight into the current thinking being employed by EPA toward consideration of the EHS issues surrounding regulatable products. On a more global scale, the Project on Emerging Nanotechnologies this week also announced the conference date and agenda for the project 'Regulating Nanotechnologies in the EU and US', which will include the
launch of its major report on "Transatlantic Regulatory Cooperation: Securing the Promise of Nanotechnologies". Finally the IEST has announced issue of new guidance for the design of AMC filtration systems.

Public engagement and interation was also in the headlines this week, with the launch of a pilot site for the new UK-based Nano&Me initiative, announcement from the CNSE that it has appointed a new co-ordinator for its NanoHealth Initiative, news from the InForm project announcing its plans to provide a boost for formulation science in nanotechnology.

Standards & Regulations

ASTM revises nanotechnology standard E2490
http://www.safenano.org/SingleNews.aspx?NewsID=782

ASTM International has announced a revision to its nanotechnology standard E2490.

IEST issues guideline for the design of AMC filtration systems http://www.safenano.org/SingleNews.aspx?NewsID=786

The Institute of Environmental Sciences and Technology (IEST) has provided guidance for the design of filtration systems to eliminate trace amounts of airborne molecular contamination (AMC).

Government & Policy

Nanomaterial Case Studies: Nanoscale Titanium Dioxide
http://www.safenano.org/SingleNews.aspx?NewsID=788

EPA releases draft document 'Nanomaterial Case Studies: Nanoscale Titanium Dioxide in Water Treatment and Topical Sunscreen'

Nanotoxicology & Ecotoxicology

Nanoparticles Affect Brain Development In Mice
http://www.safenano.org/SingleNews.aspx?NewsID=783

Japansese researchers report that maternal exposure to nanoparticles of titanium dioxide (TiO2) affects the expression of genes related to the central nervous system in developing mice

InForm project provides boost to formulation science for nanotechnologies
http://www.safenano.org/SingleNews.aspx?NewsID=785

A new 1.7 million euro EU funded project involving 17 world-leading research institutions will encourage the transfer of ideas and knowledge in formulation science for nano.

Call For Papers: Nanotechnology Exposure Assessment
http://www.safenano.org/SingleNews.aspx?NewsID=787

The International Journal of Occupational and Environmental Health is seeking submissions for a special issue exploring Human and Environmental Exposure Assessment for Nanomaterials.

Searching for engineered nanomaterials in the environment
http://www.safenano.org/SingleNews.aspx?NewsID=791

An article published in ES&T discusses the shift in environmental research related to nanomaterials away from the lab towards looking for real nanomaterials in the environment.

Identifying critical research needs for the eco-responsible development of nanotechnology http://www.safenano.org/SingleNews.aspx?NewsID=792

An article published in ACS Nano summarises the outcomes of the recent ICON - sponsored environmental workshop & identifies the critical research needs for eco-responsible nanotechnology development.

Nanotechnology Standards

2009-10-04T15:02:00.000+03:30

Nanotechnology Standards

Nano database

2009-10-04T14:40:00.002+03:30

http://community.safenano.org/blogs/rob_aitken/archive/2009/05/20/326.aspx#328
Rob Aitken:Stress testing
OECD database is a very impressive and ambitious attempt to gather together information about all of the relevant nano EHS studies which have been carried out or are currently underway. Having just gone live, it is perhaps inappropriate at this time to expect too much from this database, even though it was constructed largely from the previous database from Woodrow Wilson. Having previously worked with that database as part of our EMERGNANO project, I know well the issues which have to be addressed in order to clean the data such that it may be usefully used in analysis or future studies. In addition the need to continually add to the data, and keep it up to date is also paramount. In our EMERGNANO study we took great care to dig below the entry level data available in the database in order to identify those projects which were really relevant and were making real contributions towards resolving the questions relevant to the safety of nanomaterials. My hope had been that OECD would be similarly judicious in their data cleaning activities.

I have to say that my first attempt to derive useful information from this database has not filled me with a great level of confidence. The reason I was using the database was to prepare a talk for EuroNanoforum 2009 which will be held in Prague in June of this year. I am giving a key note speech there in the EHS session and in which I intend to lay out the European landscape. I looked at the OECD database as an information source by which to find all of the projects funded under the framework (FP7) programme. From other activities within that programme (more later) I know of approximately 15 projects with a total funding of something close to 50 million Euros which are under way or about to start. I had had understood that these projects had been added to the OEACD database.

Well it may be that they are, but they are not very easy to find! A search of funding source reveals some interesting reading. First search term “EC”, one project found ENREHS (one of IOM’s). That’s good but the “country” is identified as EC although the project is lead from the UK. Hmmmm. Second term “European”, one project found, which was in fact a regional government funded French project not an EC project. Third attempt “EU”, thirteen projects found. Ah, excellent! Closer examination however shows that only five of the relevant FP7 projects were in that search including one which came up twice. The remainder of the thirteen comprised various other national or barely relevant projects.

Next term “FP7” no projects found. Help, where are the rest of the projects? Eventually after much digging I found 10 of the 15 projects, there may be more!

Undeterred I pressed on, which of my projects are in here? No rather than that, I thought I would search for Lang Tran’s projects. I found three. That might surprise those of you had been under the impression that Lang was one of the most active and widely known researchers working in this area in Europe! It is interesting. The three which were found were “Nanoparticles an occupational hygiene review” in which I was the principal investigator. Project status described as “project is underway” (the project finished in 2004) The second one “A scoping study to indentify hazard data needs for addressing the risks presented by nanoparticles and nanotubes”, principal investigator Lang Tran, status project is underway (the project finished in 2006) The third one a risk assessment for particle exposure principal investigator Tran Lang status correctly identified as project is underway although the name under which this project is better known is PARTICLE_RISK which is not apparent from the data entry. No mention then of the CELLPEN and HARN projects which Lang has led for DEFRA over the last couple of years or of the various other projects of which Lang has been a co-author including EMERGNANO and REFNANO. Nor is there any reference to the ENPRA FP7 project which has just been funded which should also appear in this list.

Its also interesting looking at some of the projects which are on the list. You can do this by selecting all projects. I’ve pull out just a few examples, one, “The tenth annual green chemistry and engineering conference: student scholarships” this entry starts 2006, ends 2007 is to support students to attend this particular conference.

A second one, “A continuous monitor for arsenic in drinking water”?

A third one, “A fundamental study of transport within a single nanoscopic channel.” This project is about quantifying mass transport through nanoporous media and while undoubtedly it is a worthy piece of science and does have some relevance its immediate application towards risk assessment management is probably some time away. Nevertheless this project is identified as having substantial relevance.

“A nanocontact sensor for heavy metal.”, I could go on

These are just a four projects selected from the first page of twenty entries in a total of six hundred and ninety one entries. It is fair to say that the relevance of some of these projects to NANO EHS is rather mixed.

This is not intended to be overly critical of what OECD have done here. On the contrary I think what they have started is something that will in due course become an excellent tool for both researchers and policymakers in this area. However until the data contained within the database can be thoroughly cleaned and validated, a process which will take some considerable time and effort, and kept up to date, then use of the data contained therein for policy making and research prioritisation must be highly suspect.

Bioaffinity Based Biosensor and immunosensor

2009-07-04T23:38:00.004+04:30

Oxford Univ Begbroke Science Park

Bioaffinity Based Biosensor and immunosensor

Biosensor is a detection device with high analytical specificity made of layers of biological elements with biorecognition quality that are immobilized on a substrate having reversible interactions with the analyte and a signal transducer.

Immunosensors are biosensors that have antibodies as biological element.

AFM functionalised tip as force sensor
AFM’s functionalised tip with eg. biotin
The force of adhesion due to rupture can be calculated from deflection measure

Self assembled monolayers SAMs

SAMs are long chain monolayers of diverse functionalities organised on surface of noble metals or SiO2 for use as sensor arrays
Two main coupling schemes
thiol coupling
silane coupling

Advantageous techniques for characterisation of self-assembled monolayers SAMs

-ToF SIMS with elemental and molecular fingerprinting; detect distribution and location of biomolecules

-Tip enhanced Raman Spectroscopy, FT-Raman Spectroscopy for molecular recognition

-AFM tapping mode for imaging biofunctionalised surfaces, high resolution, ability to operate in liquid medium, topographical information, images of individual molecule measure molecular dimensions

-AFM as force sensing tool; AFM with functionalised tip, f-d mode probes functionality, elastic property, adhesion strength, and range of inter-atomic/molecular interactions for molecular recognition

-XPS complemented with Ellipsometric and contact angle measurement can confirm the presence of immobilized molecules

Time of Flight SIMS

SIMS secondary ion mass spectroscopy analyses mass of ions and molecular fragments ejected from surface (dept of 10-20 Å)

TOF-SIMS uses pulse primary ion beam at low fluence to ionize and desorbe the sample surface

ToF analyzer detects time of flight of secondary ions to mass spectrometer having different velocities

Mass spectrum counts of secondary ions emitted to determine molecular species.

Highly focused primary ion beam (ca 1 μ dia ) images visualising molecular distribution on the surface

MICROCANTILEVERS AS BIOLOGICAL SENSORS

Microlever Dynamic mode in micro balance method (resonance due to oscillation) measures resonant frequency changes due to added mass

Microlever Static mode in surface stress method (deflection due to bending) mode measures deflection of lever, displacement of the tip due to changes of stress or mass loading (operates both in air and liquid)

Refs:

Myhra S (Oxford Univ), A review of enabling technologies based on scanning probe microscopy relevant to bioanalysis, Biosensors and Bioelectronics, Volume 19, Issue 11, 15 June 2004, Pages 1345-1354

Bruno Pettinger, Tip-enhanced Raman scattering: Influence of the tip-surface geometry on optical resonance and enhancement, Surface Science 603 (2009) 1335–1341

Thomas Ederth (Oxford Univ), Computation of Lifshitz-van der Waals Forces between
Alkylthiol Monolayers on Gold Films, Langmuir 2001, 17, 3329-3340

Al2O3 and Si C

2009-04-25T21:59:00.003+04:30

FRACTURE, STRENGTH AND DAMAGE TOLERANCE OF CERAMIC NANOCOMPOSITES

Objectives
The objectives of the project were to investigate ceramic “nanocomposites”, principally Al2O3 / SiC:
1. To identify strengthening and damage-tolerance mechanisms
2. To optimise design of nanocomposites
3. To optimise processing of nanocomposites
Substantial progress was made in all three of these areas. We now have a “recipe” for producing a sintered (rather than hot-pressed) Al2O3 / SiC “nanocomposite”, with improved strength, toughness, damage tolerance and wear resistance, and have made good progress in understanding the mechanisms of property improvement. Since the research program focused on the links between processing, microstructure, and mechanical properties, this report deals with processing issues first, followed by mechanical property investigations, finally dealing with the mechanisms linking the two via microstructure and leading to property improvements Processing Two aspects of processing were investigated: (a) the feasibility of using sintering to produce Al2O3 / SiC nanocomposites with enhanced properties, and (b) production of hot-pressed composites with very fine SiC particle size.

Sintering Previous investigations on Al2O3 / SiC nanocomposites by other workers suggested that it is difficult to obtain near fully dense products using the pressureless sintering route. However, the flexibility of this route (in terms of the geometrical complexity of manufactured products) and its relative costeffectiveness are compelling, so a main aim of the project was to investigate this method of fabrication. For a full report on this aspect of the project see [1].

Ultra-fine SiC composites. We have been able to fabricate a range of alumina/SiC nanocomposites with mean SiC particle sizes ranging from 12 nm to 120 nm. These were fabricated by two routes, the first a conventional powder processing and the second using a novel polymer precursor route where ultrafine SiC was generated by the pyrolysis of a polycarbosilane [2,3,4,5].

Publications
1. C.C Anya and S.G. Roberts, Pressureless sintering and elastic constants of Al2O3-SiC ‘nanocomposites’, J.Eur.Cer.Soc. in press.
2. B. Su and M. Sternitzke, A novel processing route for alumina/SiC nanocomposites by Si-polymer pyrolysis, 4th Europ. Ceram. Conv. (Ed. A. Bellosi), Vol. 4 p. 109-116 (1995).
3. L. Carroll, M. Sternitzke and B. Derby, Silicon carbide particle size effects in alumina based nanocomposites, Acta Mater. 44 (1996) 4543.
4. M. Sternitzke, E. Dupas, P. Twigg and B. Derby, Surface mechanical properties of alumina based nanocomposites, submitted to Acta Mater.
5. C.C. Anya and S.G. Roberts, Indentation fracture toughness & surface flaw analysis of sintered alumina/SiC ‘nanocomposites’ J.Eur. Cer.Soc. 16 (1996) 1107

http://www-sgrgroup.materials.ox.ac.uk/abstracts/J77542.pdf

Langmuir monolayers

2009-04-25T21:50:00.001+04:30

A Langmuir–Blodgett film contains one or more monolayers of an organic material, deposited from the surface of a liquid onto a solid by immersing (or emersing) the solid substrate into (or from) the liquid. A monolayer is adsorbed homogeneously with each immersion or emersion step, thus films with very accurate thickness can be formed. This thickness is accurate because the thickness of each monolayer is known and can therefore be added to find the total thickness of a Langmuir-Blodgett Film. The monolayers are assembled vertically and are usually composed of amphiphilic molecules (see Chemical polarity) with a hydrophilic head and a hydrophobic tail (example: fatty acids). Langmuir–Blodgett films are named after Irving Langmuir and Katharine B. Blodgett, who invented this technique while working in Research and Development for General Electric Co. An alternative technique of creating single monolayers on surfaces is that of self-assembled monolayers.

Langmuir-Blodgett Films should not be confused with Langmuir films, which tends to describe an organic monolayer submersed in an aqueous solution .

http://en.wikipedia.org/wiki/Langmuir-Blodgett_film

Electron microscopy

2009-04-25T19:51:00.002+04:30

Electron microscopy and microanalysis are an integral part of many research activities of other groups in the Department, including processing, polymers and ceramics, and there is a strong interaction with the modelling group.

In recent years the Oxford EM&M Group has undergone major growth, including expansion into the Begbroke site and the installation of the world's first double aberration-corrected TEM/STEM. The group includes Professors Cockayne and Kirkland and Drs Hutchison, Jenkins and Nellist as academic staff, and is expanding into new research areas, and seeking collaborations. It has a well-developed formal and informal postgraduate training programme, in modular form, and a seminar series. An innovative schools outreach programme has a remotely accessible SEM (Oxford CyberSEM), supported by modules aimed at the school curriculum. Collaborations with JEOL through the JEOL Applications Laboratory at the Begbroke Site of the University involve the new aberration corrected FEG(S)TEM and the remote microscopy project.

http://www-em.materials.ox.ac.uk/

flexural rigidity - a measure of the resistance of the lithosphere to bending on long (i.e. > 105 years) time-scales.

flexural response function - the wavenumber parameter that modifies the Airy response to loads to produce the flexural response.

Better photocells from bigger Buckyballs: Now, a group of scientists collaborating from several research institutions, namely the Georgetown University, Washington DC, Luna Innovations Inc., Virginia, the Friedrich-Alexander-Universität, Erlangen, Germany, the National Renewable Energy Laboratory, Colorado, and the University of Santa Barbara have developed a novel fullerene species for this application [Ross, et al., Nature Materials (2009), doi:10.1038/NMAT2379].

Au/CeOx/TiO2(110)

2009-04-25T19:45:00.002+04:30

High catalytic activity of Au/CeOx/TiO2(110) controlled by the nature of the mixed-metal oxide at the nanometer level

Mixed-metal oxides play a very important role in many areas of
chemistry, physics, materials science, and geochemistry. Recently,
there has been a strong interest in understanding phenomena
associated with the deposition of oxide nanoparticles on the
surface of a second (host) oxide. Here, scanning tunneling microscopy,
photoemission, and density-functional calculations are used
to study the behavior of ceria nanoparticles deposited on a
TiO2(110) surface. The titania substrate imposes nontypical coordination
modes on the ceria nanoparticles. In the CeOx/TiO2(110)
systems, the Ce cations adopt an structural geometry and an
oxidation state (+3) that are quite different from those seen in bulk
ceria or for ceria nanoparticles deposited on metal substrates. The
increase in the stability of the Ce3+ oxidation state leads to an
enhancement in the chemical and catalytic activity of the ceria
nanoparticles. The codeposition of ceria and gold nanoparticles on
a TiO2(110) substrate generates catalysts with an extremely high
activity for the production of hydrogen through the water–gas
shift reaction (H2O+CO3H2+CO2) or for the oxidation of carbon
monoxide (2CO + O2 3 2CO2). The enhanced stability of the Ce3+
state is an example of structural promotion in catalysis described
here on the atomic level. The exploration of mixed-metal oxides at
the nanometer level may open avenues for optimizing catalysts
through stabilization of unconventional surface structures with
special chemical activity.

Park J et al, PNAS March 31, 2009 vol. 106 no. 13, 4975–4980

Nanoparticles LPSiNPs and TiO2

2009-04-16T17:41:00.003+04:30

Researchers from California and Massachusetts have come up with a new type of non-toxic nanoparticle (NP) that is efficiently broken down and excreted by the kidneys once it has delivered its drug cargo to the target organ [Park, et al., Nat. Mater. (2009), doi: 10.1038/nmat2398].

There is already a significant amount of research on drug delivery using NPs, but some of these systems suffer from major drawbacks, such as the body’s immediate rejection of NPs before they can deliver their payload, or biodegradability and toxicity of the NPs or their by-products. However, the use of NPs for drug delivery remains of major interest because these small bodies have some exceptional properties. NPs have a large specific capacity for loading drugs, they are easily detected while they are in the body, and they are retained by the blood stream long enough for them to reach their target and offload the drug.

The new 126 nm luminescent porous Si NPs (LPSiNPs) are fabricated by electrochemical etching of single-crystal Si wafers, followed by ultrasonication and filtration to obtain NPs with 5-10 nm pore diameters. Silicon oxide grown onto the surface of LPSiNPs gives them an intrinsic photoluminescence at 650-900 nm. This makes them suitable for in vivo applications as organs and tissues exhibit very low adsorption in this region and any photoluminescence can be attributed to the LPSiNPs. The luminescent material is much more photostable than fluorescein or cyanin fluorophores and has a quantum yield comparable to other water-soluble luminescent silicon-silica NPs.

In vivo tests have been carried out by the researchers who incorporated an anti-cancer drug – doxorubicin – into LPSiNPs (DOX-LPSiNPs) and injected the DOX-LPSiNPs into mice. Photoluminescence indicates that the DOX-LPSiNPs reach the tumor, where they build up. Histology of the tissues also confirms the presence of the drug together with LPSiNPs inside the tumor. The LPSiNPs then break down, most probably into soluble silicic acid and are completely eliminated from the body by renal clearance within 1-4 weeks of injection, without any signs of toxicity in the major organs of the mice.

http://www.materialstoday.com/archive/2009/12-04/news01.html

TiO2 particles in various concentrations were added into culture plated with confluent cells. After incubation for 24 hours the cell viability was then quantified with Live/Dead cytotoxicity Viability stain (Molecular Probes). The cell viabilities were then normalized with cells without treatment. Vertical lines denote ± 1 SD (n = 4 for all test samples and cells). Significance of differences between cancer cells versus 3T3 cells: P < .05.

LLC cancer cells derived from mouse tumour tissues
JHU prostate cancer cells
B16F1 and B16F10 skin melanoma cancer cells
3T3 fibroblast cells (as control)

........we find that TiO2 nanoparticles have low cytotoxicity to B16F10 and B16F1 melanoma cells as well as 3T3 fibroblasts. These findings are in agreement with many recent published results. Specifically, various sizes and concentrations of TiO2 particles have been reported to be nontoxic in cell monolayer uptake models in vitro,[40] and [41] in vitro inhalation models,3 and in vivo models.[5] and [10] However, in the case of the JHU prostate tumor cells and LLC cells, we found that there are significant differences in viability levels for uncoated TiO2 particles at concentrations of 1 mg/mL for LLC cells and 0.1 mg/mL for JHU prostate tumor cells. Our results have shown that TiO2 particles possess cell-specific toxicity, depending on the concentrations and surface functionality of the particular particles.

Thevenot P et al, Univ of Texas, Surface chemistry influences cancer killing effect of TiO2 nanoparticles, Nanomedicine: Nanotechnology, Biology and Medicine, Volume 4, Issue 3, September 2008, Pages 226-236

Solar control glass reduce the amplitude of radio waves

2009-04-16T17:31:00.002+04:30

It is a well known phenomenon that the amplitude of radio waves propagating through solar control glass is greatly reduced, because the electrical conductive film on the surface of solar control glass reflects the incident radio waves withfrequencies lower than that of the plasma oscillation of free electrons in the conductive film. As a result of the moment method analysis of the scattering problem in the spectral domain, it was found that the amplitude of radio waves was not damped when the conductive film was divided into discontinuous segments with a periodic array because the motion of free electrons induced by the magnetic field of incident radio waves is restricted in the divided film. The effect of dividing the conductive film of solar control glass has been examined experimentally in the television wave region.

H. Nakashima et al, Effect of segmentation of conductive coatings on the radio wave
transmission through solar control sheet glass,
Journal of Non-Crystalline Solids 178 (1994) 176-181

‘Casimir–Lifshitz’ force

2009-04-08T16:45:00.003+04:30

Space is not completely empty; the vacuum teams with quantum mechanical energy fluctuations able to generate an attractive force between objects that are very close to each other. This ‘Casimir–Lifshitz’ force can cause static friction or ‘stiction’ in nanomachines, which must be strongly reduced. Until now only attractive interactions have been reported but in theory, if vacuum is replaced by certain media, Casimir–Lifshitz forces should become repulsive. This has now been confirmed experimentally. Repulsion, weaker than the attractive force, was measured in a carefully chosen system of interacting materials immersed in fluid. The magnitude of both forces increases as separation decreases. The repulsive forces could conceivably allow quantum levitation of objects in a fluid and lead to new types of switchable nanoscale devices with ultra-low static friction. Levitation depends only on the dielectric properties of the various materials. The cover illustrates repulsion between a tiny gold sphere and a silica substrate (left). Replace the silica with gold (right), and the force becomes attractive.

Quantum fluctuations create intermolecular forces that pervade macroscopic bodies1, 2, 3. At molecular separations of a few nanometres or less, these interactions are the familiar van der Waals forces4. However, as recognized in the theories of Casimir, Polder and Lifshitz5, 6, 7, at larger distances and between macroscopic condensed media they reveal retardation effects associated with the finite speed of light. Although these long-range forces exist within all matter, only attractive interactions have so far been measured between material bodies8, 9, 10, 11. Here we show experimentally that, in accord with theoretical prediction12, the sign of the force can be changed from attractive to repulsive by suitable choice of interacting materials immersed in a fluid. The measured repulsive interaction is found to be weaker than the attractive. However, in both cases the magnitude of the force increases with decreasing surface separation. Repulsive Casimir–Lifshitz forces could allow quantum levitation of objects in a fluid and lead to a new class of switchable nanoscale devices with ultra-low static friction13, 14, 15.

Measured long-range repulsive Casimir–Lifshitz forces, Nature 457, 170-173 (8 January 2009) |

Nanotech food

2009-04-07T01:10:00.001+04:30

Maynard serves up the complexities of nanoscience in enticing, digestible, bite-size morsels. It is a friendly, funny, 25-minute travel guide to the technology that promises to ignite the next industrial revolution. In the video, Maynard shows products that use nanotechnology today. And he travels into the future to demonstrate how nanotechnology will change virtually everything—in medicine, energy, materials, travel and electronics.

Nanotechnology is the ability to measure, see, manipulate and manufacture things usually between 1 and 100 nanometers. A nanometer is one billionth of a meter. A human hair is roughly 100,000 nanometers wide.

http://penmedia.org/video/maynard.html

Electronagativity, polarisability and band gap in Oxides

2009-03-16T12:28:00.005+03:30

The earliest studies of conjugated molecular materials established that the mechanism behind electroluminescence was recombination of electron-hole pairs in a radiative process. This provided evidence for the existence of a band-gap within these materials, allowing comparison with inorganic semiconductors studied in the well understood eld of solid state physics. More recently, the possibility of controlling the band-gap of organic semiconductors has allowed the use of a variety of conjugated polymers in many applications, including highly sensitive chemical sensors, eld-eect transistors (OFETs), solar cells (OPVs) and high effciency organic light-emitting diodes (OLEDs).

Patric Wallace Parkinson, (Brasenose College), Ultrafast Electronic Processes at
Nanoscale Organic-Inorganic Semiconductor Interfaces, Michaelmas 2008, Doctrola Thesis

Electronagativity, polarisability and band gap in Oxides

Electronegativity, polarisability and band gap in oxides Oxygen in the oxidation state of -2 exists in oxides and oxidic compounds where the bonding is ionic, covalent or metallic. In these different types of bonding situations it has distinctly different parameters which relate to electronegativity, polarisability, etc. No other element exhibits such versatile behaviour(3,4) and it is this behaviour that imparts many of the properties to oxidic glasses. It arises, in a crude way, from oxygen being able to exist not only as bridging or nonbridging but also to exist with a degree of negative charge which can be varied, for example, by adjusting the glass composition. This negative charge should not be thought of as static but fluctuating depending on movement relative to the silicon atoms to which it is linked, and also on the proximity, movement and nature of constituent metal ions.

XA-XB=(Q/n)½

where n is the number of bonds. (For oxides, 1·1 eV must be added for each oxygen in order to correct for the double bond in the O2 molecule.)

Calculations show that in covalent oxides such as P2O5, xO is 3·5. This is the usual value quoted for oxygen in textbooks. However, for oxides where there is appreciable ionicity, there is a fall in xO. Indeed, for Cs2O, xO has fallen to 2·2. The important point that should be noted is that the oxygen atom (or rather oxide ion) has less attraction for the negative charge in the bonding as its own negative charge increases. Bearing in mind that in glass the negative charge on nonbridging oxygen atoms is greater than for bridging, it follows that there would be a decrease in oxygen electronegativity, on average throughout the network, as the proportion of basic oxide in the glass is increased.

If there is a similar trend for the band gap electronegativity, X*opt, then the smaller value of X*opt that results would have the effect of raising the top of the
valence band and this would account for the lower frequency onset of ultraviolet absorption for glasses, e.g. soda–lime–silica glasses compared with vitreous
silica.

Duffy J A, Ultraviolet transparency of glass: a chemical approach in terms of band theory, polarisability and electronegativity, Phys. Chem. Glasses, 2001, 42 (3), 151–7

MY ASHMOLEAN

2009-04-01T10:15:00.000+04:30

MY MUSEUM

This is an exciting time for the Ashmolean. In November 2009 we will unveil the Museum’s transformation, a redevelopment that is doubling our display space, and which the Oxford Times has called the ‘most significant’ in the Ashmolean’s 326-year history.

The My Ashmolean My Museum appeal has been launched to ask for your support as we reach the final stages of this historic expansion.

The architect of the new Ashmolean is Rick Mather, and the Guardian placed Rick’s ‘subtle yet major extension’ in its top five architectural highlights of 2009. His design has created 39 superb new galleries in which to display the Ashmolean’s rich and varied collections, as well as an Education Centre with its own entrance on St Giles, and Oxford’s first rooftop café.

These state-of-the-art facilities, together with inventive and engaging new displays, will allow us to build upon the position we occupy as a museum of local, national and international importance. Despite these momentous changes, entry to the Ashmolean will remain free.

The cost of the Ashmolean’s transformation is £61 million. So far we have raised nearly eighty per cent of that goal, thanks to the generous backing of the Heritage Lottery Fund, the Linbury Trust, and a number of other charitable trusts and individuals.

We are grateful to those who have already shown their support, and we hope that you will help us to reach our target. Every pound really does count.

http://www.ashmolean.org/appeal/