The Invisible World Wilson, Catherine
2020, 1995, 2020-12-08, Letnik:
2
eBook
In the seventeenth century the microscope opened up a new world of observation, and, according to Catherine Wilson, profoundly revised the thinking of scientists and philosophers alike. The interior ...of nature, once closed off to both sympathetic intuition and direct perception, was now accessible with the help of optical instruments. The microscope led to a conception of science as an objective, procedure-driven mode of inquiry and renewed interest in atomism and mechanism. Focusing on the earliest forays into microscopical research, from 1620 to 1720, this book provides us with both a compelling technological history and a lively assessment of the new knowledge that helped launch philosophy into the modern era. Wilson argues that the discovery of the microworld--and the apparent role of living animalcula in generation, contagion, and disease--presented metaphysicians with the task of reconciling the ubiquity of life with human- centered theological systems. It was also a source of problems for philosophers concerned with essences, qualities, and the limits of human knowledge, whose positions are echoed in current debates about realism and instrument-mediated knowledge. Covering the contributions of pioneering microscopists (Leeuwenhoek, Swammerdam, Malpighi, Grew, and Hooke) and the work of philosophers interested in the microworld (Bacon, Descartes, Leibniz, Malebranche, Locke, and Berkeley), she challenges historians who view the abstract sciences as the sole catalyst of the Scientific Revolution as she stresses the importance of observational and experimental science to the modern intellect.
Formula Omitted stacked dielectric-based metal-insulator-metal capacitors with different thermal and nitrogen plasma treatments (NPTs) were explored in this letter. As the Formula Omitted dielectric ...crystallizes from amorphous phase after a thermal treatment, capacitance density increasing from 7.7 to 11.9 Formula Omitted was obtained at the price of aggravating leakage current and wider distribution in device characteristics. With NPT to well passivate grain-boundary-related defects in the crystalline Formula Omitted film, devices still keep a satisfactory capacitance level of 11.2 Formula Omitted while exhibiting suppressed leakage current by a factor of 53, a lower quadratic voltage coefficient of capacitance Formula Omitted of 30 Formula Omitted, near frequency dispersion-free capacitance, a better temperature coefficient of capacitance of 82 Formula Omitted, and more controllable device uniformity. The mechanism for the improved electrical characteristics was further confirmed by atomic force microscope. These results suggest that NPT paves a new avenue to further advance the performance of crystalline dielectric-based devices.
Category: Hindfoot Introduction/Purpose: Lateralising calcaneal osteotomy (LCO) for pes cavus is generally regarded to be harder to shift than a medialising calcaneal osteotomy for pes planus. Whilst ...this may be due to tight tissues as in pes cavus, no attempt has been made to define a particular structure that could limit the lateral shift in a LCO. Some surgeons recommend releasing the flexor retinaculum routinely with a LCO to avoid a tarsal tunnel syndrome, suggesting that perhaps it is the flexor retinaculum that is the main restrictor to the lateral shift in a LCO. The purpose of our study was to define the structures that restrain the lateral shift in a calcaneal osteotomy in a cadaveric study. Methods: Calcaneal osteotomies were carried out by a single orthopaedic surgeon on 10 embalmed, below-knee cadavers. LCOs were performed using standard lateral approach and the lateral calcaneal shift was measured before and after the release of flexor retinaculum in 4 cadavers. Further exploratory dissection around the osteotomy site, however, revealed that abductor hallucis muscle must be the main restraint to the lateral shift of the calcaneus. Subsequently, LCO was performed on another 6 cadavers and the abductor hallucis muscle fascia as well as the plantar fascia was released. The lateral shift was measured before and after the fascia releases, and compared with those of the flexor retinaculum release. Results: The average shift with a LCO by itself in the first 4 cadavers was similar to the last 6 (4.5 mm and 5.5 mm respectively). Releasing the flexor retinaculum created a further 3 mm lateral shift on average; however, release of abductor hallucis muscle fascia and the plantar fascia increased lateral shift by an additional 7 mm on average; which is an extra 4 mm shift on average compared with those of flexor retinaculum release. Conclusion: The results of this study suggest that the abductor hallucis muscle along with the plantar fascia is one of the main structures limiting the lateral shift in LCO, and release of fascia over this muscle as well as the plantar fascia should be an essential part of the lateralizing calcaneal osteotomy.
A method is proposed to compute and synthesize a microrelief to produce a new nano-optical element for forming 3D images with full parallax at the zero order of diffraction. The synthesis of ...nano-optical elements requires the use of multilevel structures. A method is developed for the first time to compute the phase function of such nano-optical elements. Optical security elements that produce the new security feature are synthesized using electron-beam technology. The accuracy of microrelief formation is 10 nm in terms of depth. A sample optical security element is manufactured, which when illuminated by white light, forms a 3D image at the zero order of diffraction. Photos and video of the new 3D visual effect exhibited by real optical elements are presented. The optical elements developed can be replicated using standard equipment employed for manufacturing security holograms. The new optical security feature is easy to control visually, safely protected against counterfeiting, and designed to protect banknotes, documents, ID cards, etc.
Nanomaterials exhibit structural and functional heterogeneity among individual nanoparticles, thus requiring a capability to study single nanoparticles. While electron microscopes often provide ...static images of their chemical composition, morphology and structure, imaging the chemical activity of single nanoparticles is highly desirable for exploring the structure-activity relationship
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a bottom-up strategy, to understand their microscopic reaction mechanisms and kinetics, and to identify a minority subpopulation with extraordinary activity. Recently, various optical microscopes have been emerging as powerful techniques towards this goal, owing to their non-invasive nature, excellent sensitivity, diversified spectroscopic principles and sufficient spatial and temporal resolution. In this review, we first introduce the motivational concept and the strength of using optical microscopy to study the chemical activity of single nanoparticles. In the second section, five types of commonly used optical microscopy, fluorescence microscopy, dark-field microscopy, surface plasmon resonance microscopy, Raman microscopy and photothermal microscopy are described, with an emphasis on their applicable nanomaterials and mechanisms for application. Recent achievements of these techniques in nanosensing, nanoelectrochemistry and nanocatalysis are surveyed and summarized in the subsequent sections, respectively. We finally conclude with our perspective on the remaining challenges and the future trends in this field.
Chemical activity of single nanoparticles can be imaged and determined by monitoring the optical signal of each individual during chemical reactions with advanced optical microscopes. It allows for clarifying the functional heterogeneity among individuals, and for uncovering the microscopic reaction mechanisms and kinetics that could otherwise be averaged out in ensemble measurements.
Nearly all single-particle cryo-EM structures resolved to better than 4-Å resolution have been determined using 300-keV transmission electron microscopes (TEMs). We demonstrate that it is possible to ...obtain reconstructions of macromolecular complexes of different sizes to better than 3-Å resolution using a 200-keV TEM. These structures are of sufficient quality to unambiguously assign amino acid rotameric conformations and identify ordered water molecules.
Transmission electron microscopy (TEM) of rapidly frozen biological specimens, or cryo-EM, would benefit from the development of a phase plate for in-focus phase contrast imaging. Several types of ...phase plates have been investigated, but rapid electrostatic charging of all such devices has hindered these efforts. Here, we demonstrate electron phase manipulation with a high-intensity continuous-wave laser beam, and use it as a phase plate for TEM. We demonstrate the laser phase plate by imaging an amorphous carbon film. The laser phase plate provides a stable and tunable phase shift without electrostatic charging or unwanted electron scattering. These results suggest the possibility for dose-efficient imaging of unstained biological macromolecules and cells.
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