Instrumentation Micro/nano

In principle, it can be envisaged that a thermal probe could be used in conjunction with an optical microscope that would image the sample surface to facilitate selection of the locations for analysis in other words, an atomic force microscope is not strictly necessary. In practice, all micro/nano-TA to date has been performed using an AFM, so we will consider this option only in this section. In its modern form micro/nano-TA can be interfaced with a wide range of AFMs, and so exact details of the procedure will vary from instrument to instrument, here we will discuss generic requirements. 

At the time of writing there is only one manufacturer of micro/nano-TA equipment Anasys Instruments, (www.anasysinstruments.com). They supply the hardware and software for local thermal analysis and thermal imaging that can be interfaced with the most popular types of atomic force microscope. More recently they have launched an instrument based on an optical microscope, the Vesta system, which is simpler to use than an atomic force microscope but the spatial resolution is limited to approximately 1.5 micrometers, see Fig. 7.22. The Wollaston probes are supplied by Veeco (www.veeco.com) and are, therefore, compatible only with Veeco AFMs. The nanoprobes are supplied by Anasys Instruments and can be used with most popular makes of AFM. In addition, Anasys Instruments supply calibration kits containing temperature standards. More recently they have launched an instrument based on an optical microscope, the Vesta system, which is simpler to use than an atomic force microscope, but the spatial resolution is limited to approximately 1.5 pm. 

Column diameter is an important parameter to consider in life science applications in which sample amounts are very limited and the components of interest may not be abundant. Researchers have reviewed micro HPLC instrumentation and its advantages.910 Nano LC-MS offers 1000- to 34,000-time reductions in the dilution of a sample molecular zone eluted from nano LC columns of 25 to 150 [Mi IDs in comparison to a 4.6 mm ID column. This represents a large enhancement of ion counts in comparison to counts obtained for the same amount of sample injected into a conventional 4.6 mm column. Solvent consumption for an analysis run or sample amount required for injection in a nano LC application may be reduced 1000 to 34,000 times compared to amounts required by an analytical column operated at a 1 mL/min flow rate. 

Two basic requirements must be met for the instrumental technique when it is applied in art conservation research sensitivity, for obtaining relevant data from small samples on the nano, micro or mill (-gram, -meter) scale and specificity, for unambiguously identifying compounds and quantifying the analytes from the complex mixtures of substances that form the materials present in the monument or artwork. Other requirements are also desirable for an analytical method when it is applied to objects of artistic, historic, and archaeological nature according to Lahanier et al. [2], these are ... 

From a practical point of view, the discussion on flow-rate can be summarized as follows. In LC-APCI-MS, the typical flow-rate is 0.5-1.0 ml/min. For routine applications of LC-ESI-MS in many fields, extreme column miniaturization comes with great difficulties in sample handling and instrument operation. In these applications, LC-MS is best performed with a 2-mm-ID column, providing an optimum flow-rate of 200 pFmin, or alternatively with conventional 3-4.6-mm-ID columns in combination with a moderate split. In sample limited cases, further reduction of the column inner diameter must be considered. Packed microcapillary and nano-LC columns with micro-ESI and nano-ESI are rontinely applied inproteomics stndies (Ch. 17.5.2). 

Current micro LC applications are primarily in micropurifications of pro-teins/peptides and in proteomics research. Chapter 4 discusses the stringent instrumentation requirements for micro and nano LC, which must have instruments with very low dispersion and dwell volumes. 

Low-dispersion HPLC systems are necessitated by the increasing trend of using shorter and narrower HPLC columns, which are more susceptible to the deleterious effects of extra-column band-broadening. HPLC manufacturers are designing newer analytical HPLC systems with improved instrumental bandwidths compatible with 2-mm i.d. columns by using micro injectors, smaller i.d. connection tubing, and detector flow cells. A new generation of ultra-low dispersion systems dedicated for micro and nano LC is also available. 

This aspect has led to the production of micro- and nanoelectrospray sources, where the chromatographic eluate flow is in the range 1-10 2 pL/min. A typical instrument setup for nano-ESI experiments is shown in Fig. 1.10. In this case, the supplementary gas flow for spray generation is no longer present and the spray formation is only due to the action of the electrical field. The sprayer capillary, with an internal... 

A significant reduction of the column ID put stringent demands on the instrumentation for micro-LC as all volumetric extra-column dispersion contributions must be down scaled accordingly. Initial developments in this area were achieved on modified standard LC instruments. For approximately 10 years, dedicated instrumentation for micro-, capillary-, and nano-LC has become commercially available and was recently discussed [33]. 

In situ TEM can be performed to study the optical, electrical, and mechanical properties of materials. The instrumentation involved considers several types of specimen holders. At present, the main types of specimen probes used in industry are electrical probing (TEM-STM) [32], micro-force (TEM-nanoindenter) [33], nano-force (TEM-AEM) [34, 35], optical, scanning fiber, multiple electrical wire. 

Hoppe, K., Fahmer, W.R., Fink, D. et al. 2008. An ion track based approach to nano- and micro-electronics. Nuclear Instruments and Methods in Physics Research B 266 1642-1646. 

Rosiak, J. M., Janhc, I., Kadubowski, S. et al. 2003. Nano-, micro- and macroscopic hydrogels synthesized by radiation technique. Nuclear Instruments and Methods in Physics Research B 208 325-330. 

As mentioned above, ESI instruments were coupled to liquid chromatography. The biggest impact in ESI MS has been the adaptation to reduced flow capabilities in the 10-500 nl/min range. Wilm and Mann [115] and Emmett and Caprioli [116] developed such improvements in parallel. The combination of nano-flow LC with micro-capillary reversed phase HPLC and nano-ES has i) dramatically improved the sensitivity of ESI-MS/MS and ii) enabled the automation of protein identification by using an auto sampler for loading of samples onto the LC [117]. 

Hardness and mechanical moduli of polymer blends were determined with a Micro materials Nano Test 600 apparatus (UK), applying the procedure of spherical indentation with 10% partial unloading. R=5 pm stainless steel spherical indenter probed the surface layer of material with the loading speed of dP/dt=0.2 mN/s, reaching depths up to 8.0 pm. More information on the instrumentation can be found elsewhere [13]. 

Instruments are available from several manufactmers, including TA Instruments and GE Healthcare Life Sciences. Some companies use micro in their instrument names, some use nano, and some use the Greek letter p in their names. For the sake of simplicity, the term micro will be used unless a specific instrument is discussed by name. 

An increase in the accuracy of creep measurements has always been of importance but recently it has become a focal research problem for two reasons. First, the development of novel highly precise instruments for measuring creep rates is necessary in the context of increased interest in studies being performed on the micro-, submicro-, and even nano-levels. Second, it may a priori be assumed that creep behavior of polymeric materials is associated intimately with their basic physical characteristics, namely, molecular dynamics and supermolecular structure. However, the common widespread methods of the deformation measurements provide a rather smoothed picture and often allow no discerning of the fine effects depending on the changes in dynamics and structure of materials. 

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