Results 1 - 10 of 6914
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[en] A comparative study between the standard Washburn macroscale method for determination of the capillary wetting rate in a nonwoven textile fibre mesh and the polarization optical video-microscopy-based microscale method for investigation of the wetting process in single fibres is reported. The study was performed with profiled polyester fibres associated with superior wicking performance. Both methods resulted in very similar values of the wetting rate, which confirms that for textile materials based on such type of fibres the microstructure of a single fibre dictates liquid transport properties on the micro- as well as on the macroscale. Consequently, for such materials the microscale method is fully competitive with the standard macroscopic approaches. (paper)
[en] In the past two decades or so, there has been a renaissance of optical microscopy research and development. Much work has been done in an effort to improve the resolution and sensitivity of microscopes, while at the same time to introduce new imaging modalities, and make existing imaging systems more efficient and more accessible. In this review, we look at two particular aspects of this renaissance: computational imaging techniques and compact imaging platforms. In many cases, these aspects go hand-in-hand because the use of computational techniques can simplify the demands placed on optical hardware in obtaining a desired imaging performance. In the first main section, we cover lens-based computational imaging, in particular, light-field microscopy, structured illumination, synthetic aperture, Fourier ptychography, and compressive imaging. In the second main section, we review lensfree holographic on-chip imaging, including how images are reconstructed, phase recovery techniques, and integration with smart substrates for more advanced imaging tasks. In the third main section we describe how these and other microscopy modalities have been implemented in compact and field-portable devices, often based around smartphones. Finally, we conclude with some comments about opportunities and demand for better results, and where we believe the field is heading. (review)
[en] "Quanten 8" contains the lectures on the general meeting of the Heisenberg Society in September 2019. The physicist Thomas Klar reports on the discovery of the highest resolution optical microscopy with the help of lasers, which was awarded the Nobel Prize for Chemistry to Eric Betzig, Stefan Hell and William Moerner. Barbara Blum-Heisenberg impressively describes how music and philosophy worked as sources of creativity for her father Werner Heisenberg. The original German version of the lecture Heisenberg gave in 1955 on the occasion of Niels Bohr's 70th birthday in Copenhagen is also printed. He describes the development of the interpretation of quantum theory therein, which became known as the Copenhagen Interpretation.
[de]"Quanten 8" enthält die Vorträge der Mitgliederversammlung der Heisenberg-Gesellschaft im September 2019. Der Physiker Thomas Klar berichtet über die mit dem Nobelpreis für Chemie an Eric Betzig, Stefan Hell und William Moerner ausgezeichnete Entdeckung der höchstauflösenden optischen Mikroskopie mit Hilfe des Lasers. Barbara Blum-Heisenberg schildert eindrücklich, wie Musik und Philosophie bei ihrem Vater Werner Heisenberg als Quellen der Kreativität wirkten. Weiterhin ist die deutsche Urfassung des Vortrages, den Heisenberg 1955 zum 70. Geburtstag von Niels Bohr in Kopenhagen gehalten hat, abgedruckt. Er beschreibt darin die Entwicklung der Deutung der Quantentheorie, die als Kopenhagener Interpretation bekannt wurde.
[en] We describe a unique and convenient approach to multimodal hyperspectral optical microscopy, herein achieved by coupling a portable and transferable hyperspectral imager to various optical microscopes. The experimental and data analysis schemes involved in recording spectrally and spatially resolved fluorescence, dark field, and optical absorption micrographs are illustrated through prototypical measurements targeting selected model systems. Namely, hyperspectral fluorescence micrographs of isolated fluorescent beads are employed to ensure spectral calibration of our detector and to gauge the attainable spatial resolution of our measurements; the recorded images are diffraction-limited. Moreover, spatially over-sampled absorption spectroscopy of a single lipid (18:1 Liss Rhod PE) layer reveals that optical densities on the order of 10-3 may be resolved by spatially averaging the recorded optical signatures. We also briefly illustrate two applications of our setup in the general areas of plasmonics and cell biology. Most notably, we deploy hyperspectral optical absorption microscopy to identify and image algal pigments within a single live Tisochrysis lutea cell. Overall, this work paves the way for multimodal multidimensional spectral imaging measurements spanning the realms of several scientific disciples.
[en] We investigated the interactions between selected organic tanning agents and type I fibrillar collagen as a model fibrillar substrate to enable the fast direct evaluation and validation of interpretations of tanning activity. Type I fibrillar collagen (1%) as gel was used as substrate of tanning and tannic acid, resorcinol- and melamine-formaldehyde and their combination at three concentrations as crosslinking agents (tannins). To evaluate the stability of collagen during tanning, the crosslinked gels at 2.8, 4.5 and 9.0 pHs were freeze-dried as discs which were characterized by FTIR, shrinkage temperature, enzymatic degradation and optical microscopy, and the results were validated by statistical analyses. The best stability was given by combinations between resorcinol- and melamine-formaldehyde at isoelectric pH
[en] The micro-cellular foaming of two Low-density Polyethylene (LDPE) composites as the temperature increased from 140 °C to 160 °C was investigated through visualization technology with the XTL-550E OM (optical Microscopy), with which, in situ observations during heating were carried out. The results demonstrated that the relationships of N-t and D-t followed the Boltzmann and Logistic functions with higher correction coefficients beyond 0.97 through non-linear fitting. Also, the three stages (Less-foamed, Fine-foamed and Over-foamed) were obtained by the first and second derivatives of the fitting curve: (1) the first stage was the less-foamed with the rate and driving force for the cell formation as well as the growth increase with temperature; (2) the second stage was the fine-foamed with competitive interaction between the formation rate and the growth rate; (3) the third stage was the over-foamed with the formation rate and driving force at an almost zero value. Moreover, the demarcation points of the three stages by the derivatives were almost consistent with the results through the fitting equation (t 0.5 and t max) and experimentation. By contrast, certain differences existed for the three stages in the two LDPE composites. These were attributed to the heterogeneous nucleation and strengthening towards the LDPE matrix of the nano-Montmorillonite (nano-OMMT). (paper)
[en] In the field of optical microscopy, height valuations, or calibrations, are critical to ensure accuracy and traceability. Height assessment, however, may be controversial, particularly for measurements on large steps or narrow grooves. Thus, standard setting and instrument operations are essential. In this paper, the limited energy lost (LEL) method, which is a Chinese solution, and the well-known ISO W/3 method were both applied in a two-year round robin test to verify their theoretical compatibility and promote their corresponding applications throughout China. The results show that the LEL method successfully predicted outlier growth for progressively narrowing grooves. In addition, compared with the W/3 method, 71% of the results from 24 measurements showed improved repeatability when applying the LEL method. This paper supports the LEL method with evidence from a large sample, after its original publishing in 2016 and the subsequent publication, as a key part of China’s standard on confocal microscopy, in 2017. These results indicate that dynamic model-based valuation might be the future trend for 3D optical micro-nano metrology. (paper)
[en] Since its invention in 1930, Zernike phase contrast has been a pillar in optical microscopy and more recently in x-ray microscopy, in particular for low-absorption-contrast biological specimens. We experimentally demonstrate that hard-x-ray Zernike microscopy now reaches a lateral resolution below 30 nm while strongly enhancing the contrast, thus opening many new research opportunities in biomedicine and materials science.