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71.
Dinatural transformations, which generalise the ubiquitous natural transformations to the case where the domain and codomain functors are of mixed variance, fail to compose in general; this has been known since they were discovered by Dubuc and Street in 1970. Many ad hoc solutions to this remarkable shortcoming have been found, but a general theory of compositionality was missing until Petri?, in 2003, introduced the concept of g-dinatural transformations, that is, dinatural transformations together with an appropriate graph: he showed how acyclicity of the composite graph of two arbitrary dinatural transformations is a sufficient and essentially necessary condition for the composite transformation to be in turn dinatural. Here we propose an alternative, semantic rather than syntactic, proof of Petri?'s theorem, which the authors independently rediscovered with no knowledge of its prior existence; we then use it to define a generalised functor category, whose objects are functors of mixed variance in many variables, and whose morphisms are transformations that happen to be dinatural only in some of their variables.We also define a notion of horizontal composition for dinatural transformations, extending the well-known version for natural transformations, and prove it is associative and unitary. Horizontal composition embodies substitution of functors into transformations and vice-versa, and is intuitively reflected from the string-diagram point of view by substitution of graphs into graphs.This work represents the first, fundamental steps towards a substitution calculus for dinatural transformations as sought originally by Kelly, with the intention then to apply it to describe coherence problems abstractly. There are still fundamental difficulties that are yet to be overcome in order to achieve such a calculus, and these will be the subject of future work; however, our contribution places us well in track on the path traced by Kelly towards a calculus of substitution for dinatural transformations.  相似文献   
72.
73.
Electronic textiles are a promising candidate for futuristic multifunctional clothes. However, the fabrication of robust and reproducible printed electrodes with high mechanical durability, high biocompatibility, and stable electrical performance under various mechanical deformations continues to pose a challenge. In this study, a silk fabric with printed carbon nanotube (CNT) patterns is used to produce a smart electronic textile (E-textile) for multifunctional applications. The printed CNT electrodes are used in triboelectric devices, electrically activated heaters, real-time electrophysiological sensors, and tactile sensors. The E-textile can be used as an electrically activated thermal patch to generate heat on cloth for providing warmth to the human skin and for therapy. Owing to the micro hierarchical pores of the fabric, skin contact generates a power density of about 0.7 mW cm−2 via effective contact electrification.  相似文献   
74.
The characteristics of synchronous and phase difference bubble pairs in axisymmetric configuration near a boundary are investigated experimentally by the spark discharge method. Their destructive forces on nearby boundaries are measured using a polyvinylidene fluoride sensor. The bubble pair interactions and deformed features in the boundary vicinity are dissimilar to those in bulk water. Moreover, significant discrepancies between in-phase and out-of-phase pair interactions and their intensities of impulses are also witnessed. The interbubble distance (η), stand-off distance from the boundary (γ), and phase offset (τ) are crucial parameters affecting the shape evolutions and impulsive forces. From the qualitative analysis of sensor acquisition and high-speed imaging, it is observed that bubble periods are either prolonged or shorter than their corresponding isolated single cavity according to different parameters and arrangements. Additionally, the strongest impingements are produced by in-phase pairs. The impulses of phase difference bubble pairs are remarkably lower than in-phase pairs and even lower than a single bubble in some arrangements.  相似文献   
75.
Surface acoustic wave (SAW)-based acoustofluidics has shown significant promise to manipulate micro/nanoscale objects for biomedical applications, e.g. cell separation, enrichment, and sorting. A majority of the acoustofluidic devices utilize microchannels with rectangular cross-section where the acoustic waves propagate in the direction perpendicular to the sample flow. A region with weak acoustic wave intensity, termed microchannel anechoic corner (MAC), is formed inside a rectangular microchannel of the acoustofluidic devices where the ultrasonic waves refract into the fluid at the Rayleigh angle with respect to the normal to the substrate. Due to the absence of a strong acoustic field within the MAC, the microparticles flowing adjacent to the microchannel wall remain unaffected by a direct SAW-induced acoustic radiation force (ARF). Moreover, an acoustic streaming flow (ASF) vortex produced within the MAC pulls the particles further into the corner and away from the direct ARF influence. Therefore, a residue of particles continues to flow past the SAWs without intended deflection, causing a decrease in microparticle manipulation efficiency. In this work, we introduce a cross-type acoustofluidic device composed of a half-circular microchannel, fabricated through a thermal reflow of a positive photoresist mold, to overcome the limitations associated with rectangular microchannels, prone to the MAC formation. We investigated the effects of different microchannel cross-sectional shapes with varying contact angles on the microparticle deflection in a continuous flow and found three distinct regimes of particle deflection. By systematically removing the MAC out of the microchannel cross-section, we achieved residue-free acoustofluidic microparticle manipulation via SAW-induced ARF inside a half-circular microchannel. The proposed method was applied to efficient fluorescent coating of the microparticles in a size-selective manner without any residue particles left undeflected in the MAC.  相似文献   
76.
Terahertz time-domain spectroscopy is a useful tool for material characterization because it provides both temporal and frequency domain information. In this work, we perform terahertz time-domain spectroscopy for evaluation of commercial moisturizing cream cosmetics. By measurement of terahertz transmission, the change of complex refractive index by exposure of the cosmetic samples in ambient condition is obtained. The tendency of terahertz transmission change is different from that of mass change, which implies that terahertz response becomes a new characterization tool for moisturizing cosmetics. Our results show that terahertz time-domain spectroscopy has potential application on cosmetic testing.  相似文献   
77.
Studying the complex quantum dynamics of interacting many-body systems is one of the most challenging areas in modern physics. Here, we use machine learning (ML) models to identify the symmetrized base states of interacting Rydberg atoms of various atom numbers (up to six) and geometric configurations. To obtain the data set for training the ML classifiers, we generate Rydberg excitation probability profiles that simulate experimental data by utilizing Lindblad equations that incorporate laser intensities and phase noise. Then, we classify the data sets using support vector machines (SVMs) and random forest classifiers (RFCs). With these ML models, we achieve high accuracy of up to 100% for data sets containing only a few hundred samples, especially for the closed atom configurations such as the pentagonal (five atoms) and hexagonal (six atoms) systems. The results demonstrate that computationally cost-effective ML models can be used in the identification of Rydberg atom configurations.  相似文献   
78.
79.
We carried out first-principles electronic structure calculation to study the structural stability and magnetic properties of Mn-doped WS2 ultra-thin films within the density functional theory. Adopting various configurations of Mn doping into WS2 bilayer, we find that the magnetic phase can be manipulated among the ferromagnetic, antiferromagnetic, or ferrimagnetic phases by altering doping level and growth environment. Magnetic phase and strength are determined by magnetic coupling of Mn dopants 3d electrons which can be attributed crucially to the exchange interaction mediated by neighboring S atoms 3p electrons. Accompanying to the magnetic phase transition, the electronic structure reveals that transport properties switch from semiconducting with various bandgap to half-metallic states. This result implicates possible way to develop magnetic semiconductors based on Mn doped 2D WS2 ultra-thin films for spintronics applications.  相似文献   
80.
We report a phenomenological observation of electric-field-induced formation and manipulation of liquid ball on an outer wall of the pulled pipette by using the quartz tuning fork-based atomic force microscope (QTF-AFM). The dye molecule solution with excitation wavelength of 488 nm and detection efficiency of 95% is used to investigate the movement characteristics of liquid droplets when the electric field is applied. The ejected liquid solution forms a microscale liquid droplet at the apex of the pipette by the application of electric field, containing dye molecules, which climbs up along the negatively charged outer surface of the pipette due to the electro-osmosis effect. With positive or negative bias voltages, we manipulate a liquid ball to slide upward or downward, respectively. This field-induced transport of a liquid droplet may be useful to nano-biotechnology or droplet-based microfluidic technology, for example, noncontact delivery and manipulation of liquid solution in the form of separated droplets.  相似文献   
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