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Single-Molecule Manipulation by Magnetic Tweezers
Published in Shuo Huang, Single-Molecule Tools for Bioanalysis, 2022
The magnetic tweezers arrangement is based on an inverted microscope (Eclipse Ti-U, Nikon, Japan) equipped with a 4× air objective and a 100× oil-immersion objective. A piezo objective actuator (PI, Germany) is used to finely adjust the focal plane of the objective. A motorized linear translation stage (PI, Germany) is used to adjust the distance between the permanent magnets and the sample. A collimated LED lamp (Thorlabs, USA) is installed at the back port of the microscope to illuminate the sample (Figure 5.16a). Both the piezo objective actuator and the motorized stage are controlled by a custom LabVIEW program. Microscopic images are captured and analyzed in real time to get the three-dimensional location of the paramagnetic bead. Calibration of the setup must be performed prior to the measurement.
Three-Dimensional Evaluation of Paper Surfaces Using Confocal Microscopy
Published in Terrance E. Conners, Sujit Banerjee, Surface Analysis of Paper, 2020
Marie-Claude Béland, Patrice J. Mangin
The actual resolution of a focal plane is highly dependent on particular acquisition conditions (e.g., image format, wavelength of light source, objective used, pinhole size, depth of the focal plane within the object, and signal-to-noise ratio). Consequently, it is not easily determined. The theoretical resolution is often given in terms of the full-width-half-maximum (FWHM) value of the intensity curves obtained for a point form object. The FWHM represents the distance from the point form object where the intensity has decreased to half its peak value. The performance of Leica objectives in the reflection mode is shown in Figure 5 for a wavelength of 488 nm. Resolution improves with increasing numerical aperture (larger lens opening). At a constant numerical aperture, the axial resolution is better for an air objective than for an oil immersion objective. Using a 16X air objective with a 0.45 numerical aperture gives a lateral resolution of about 0.5 μm and an axial resolution of approximately 2.5 μm. Changing the magnification changes these calculated resolution values.
Optical Signal Transduction with an Emphasis on the Application of Surface Plasmon Resonance (SPR) in Antibody Characterisation
Published in Richard O’Kennedy, Caroline Murphy, Immunoassays, 2017
Caroline Murphy, Aoife Crawley, Hannah Byrne, Kara Moran, Jenny Fitzgerald, Richard O’Kennedy
SPR sensors are also being constructed using silver sensing layers (as opposed to gold). Gold requires a layer of titanium (Ti) or chromium (Cr) between it and the glass, so the thicker sensing layer causes a broadening of the SPR signal. Silver attaches easily to glass substrates and hence the SPR signal produced has a very sharp curve and therefore displays better sensitivities. Unfortunately, when using silver, harmful sulphidisation and oxidation may affect the ligand if the silver is not properly protected using 11-mercaptoundecanoic acid (11-MUA) [78]. The prism configuration of SPR imaging is limited by physical constraints and can result in poor spatial resolution. A solution that has shown promise, proposes an ‘objective-type surface plasmon resonance imaging (SPRI)’ approach that utilises a high numerical aperture oil immersion objective and an inverted microscope [79].
Colourful 3D anti-counterfeiting label using nanoscale additive manufacturing
Published in Virtual and Physical Prototyping, 2023
Sida Peng, Shengzhi Sun, Yi Zhu, Jianrong Qiu, Huayong Yang
The printed microstructures were characterised by an optical microscope (VHX-5000, Keyence) and a field emission scanning electron microscopy (SEM, HITACHI SU-70) at an accelerating voltage of 3.0 kV. The absorption spectra of photoresists were obtained with an ultraviolet spectrophotometer (Lambda 950, PerkinElmer). Micro-region fluorescent spectra were explored by an optical microscope (Hangzhou SPL Photonics Co., Ltd) under excitation with a 366 nm semiconductor CW laser source. The fluorescence was collected by a 20× objective lens and coupled to a fibre optic spectrometer (QEPro, Ocean Optics). During the measurement, the ultraviolet pump intensity was set below the damage threshold of the printed samples. The internal quantum efficiency was measured by UV–NIR absolute PL quantum yield spectrometer (Quantaurus-QY Plus, Hamamatsu Photonics, Japan). The fluorescent images of 2D patterns were taken by a commercial microscope (DM 2500, Leica) with an objective lens (100×, NA = 1.30, Leica) under excitation with UV light. 3D fluorescent patterns were taken by a commercial inverted microscope (LSM880 AxioObserver, Carl Zeiss) with an oil-immersion objective (63×, NA = 1.40, Carl Zeiss). The depth of focus is around 0.40 μm for each z-layer. The samples were excited by semiconductor CW lasers with different wavelengths (405 nm for the blue channel, 488 nm for the green channel and 561 nm for the red channel).
Enhancement of coking potential of coals with improvised crushing mechanism
Published in International Journal of Coal Preparation and Utilization, 2022
Ajinkya Meshram, P S Dash, D Nag, R Singh
Coals are organo-sedimentary rocks originating from a variety of plant materials and different tissues. Because of this mixture, coal becomes heterogeneous and complex rock reflecting the original constituents and the conditions of depositions during formation. The usual means of examining coal is by optical microscope with reflected light under oil immersion. Under the microscope the coal can be seen as more fundamental organic constituents, each of which has a certain homogeneity of appearance called macerals. The coals are categorized into three major groups, namely, Vitrinite, Liptinite, and Inertinite. The relative compositions of these macerals define the nature of coals as coking or non-coking. The coke making process is a complex process of devolatilization of coal where not only chemical but physical structure of coal changes to form a hard-porous mass called coke. During the coke making, macerals like vitrinite and liptinite react to give rise to mosaic texture and thus called reactive macerals, whereas the inertinite does not participate much in the reaction but imparts strength to the coke matrix.
Difference in structural chemistry of non-coking and coking coal using acid treatment demineralization technique
Published in International Journal of Coal Preparation and Utilization, 2022
Soumitra Ghorai, Bidisha Ghosh, Vimal Kumar Chandaliya, Rashmi Singh, Pratik Swarup Dash, Dipakranjan Mal
The most widespread method of petrographic examination of coal in sedimentary rocks is the use of reflected white light microscopy on polished surfaces of high quality under oil immersion to enhance component or maceral reflectance differences. Oil immersion Microscopic analysis of coal which includes ‘Determination of Maceral composition of coal (IS 9127: Part 3: 2002)’ and ‘Mean Random Reflectance of vitrinite (IS 9127: Part 5: 2004/ISO 7404–5: 1994)’ was carried out at Coal and Coke Petrography laboratory of Tata Steel. Polished epoxy mounted pellets were prepared for petrographic studies as per IS 9127: Part 2: 2002 from – 1 mm size of representative coal samples using the cold setting compound. Pellets were studied under 50X oil immersion lens and 10X objective lens using Leica DMRX reflected light microscope. Point counting method (500 counts per pellet) was used to quantify different maceral groups. Vitrinite Mean Random Reflectance (Ro) was measured in monochromatic light (wavelength: 546 nm) and finally V-step distribution was calculated.