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1.
The bulk synthesis of fluorescent colloidal SU‐8 polymer rods with tunable dimensions is described. The colloidal SU‐8 rods are prepared by shearing an emulsion of SU‐8 polymer droplets and then exposing the resulting non‐Brownian rods to ultrasonic waves, which breaks them into colloidal rods with typical lengths of 3.5–10 µm and diameters of 0.4–1 µm. The rods are stable in both aqueous and apolar solvents, and by varying the composition of apolar solvent mixtures both the difference in refractive index and mass density between particles and solvent can be independently controlled. Consequently, these colloidal SU‐8 rods can be used in both 3D confocal microscopy and optical trapping experiments while carefully tuning the effect of gravity. This is demonstrated by using confocal microscopy to image the liquid crystalline phases and the isotropic–nematic interface formed by the colloidal SU‐8 rods and by optically trapping single rods in water. Finally, the simultaneous confocal imaging and optical manipulation of multiple SU‐8 rods in the isotropic phase is shown.  相似文献   

2.
By exploiting the thermoplastic and photosensitive nature of SU‐8 photoresists, different types of hierarchical pillar arrays with variable aspect ratios are fabricated through capillary force lithography (CFL), followed by photopatterning. The thermoplastic nature of SU‐8 enables the imprinting of micropillar arrays with variable aspect ratios by CFL using a single poly(dimethylsiloxane) mold, simply by tuning the initial film thickness of SU‐8 on a substrate. The pillar array is subsequently photopatterned through a photomask, followed by post‐exposure baking above the glass transition temperature (Tg) of SU‐8. The pillars in the exposed region become highly crosslinked and, therefore, neither soluble nor able to reflow above Tg, whereas the pillars in the unexposed regions can reflow and flatten out. Two developing strategies are investigated after UV exposure of the SU‐8 pillar arrays including i) solvent development and drying and ii) thermal reflow to create bilevel hierarchical structures with short pillars and single‐level, dual‐scaled, high‐aspect‐ratio (up to 7.7) pillars in a microdot array, respectively.  相似文献   

3.
A new generation of beam deflection technique is the basis for the development of electron beam (EB) technologies, which are not realisable with conventional methods. A high frequency 3D‐beam deflection makes possible multi‐field, multi‐pool and multi‐process technologies for EB welding und EB surface treatment, which result in a clear higher productivity and new combinations of properties.  相似文献   

4.
The limiting dilution assay (LDA) is a clonogenic drug efficacy test designed to determine a value for drug efficacy based on an all‐or‐none (positive or negative) response within replicates. It also attempts to calculate minimum cell numbers for cells to form colony in each drugged conditions, wherein a large value implies high drug efficacy (as a large number of extant cells are required to start a colony). However, traditional LDAs are time‐consuming to set up, often requiring many replicates for statistical analysis, and manual colony identification under a microscope to determine a positive or negative response is tedious and is susceptible to human error. To address these issues, a high‐throughput miniaturized LDA assay is developed using a micropillar/microwell chip platform using an automatic colony identification method. Three glioblastoma multiforme (GBM) brain tumor isolates (448T, 464T, and 775T) are used to test this new assay, using the c‐Met kinase inhibitors SU11274 and PHA665752 as the target drugs. The results show that the minimum cell number of 775T is larger than that of the other two cell types (SU11274 and PHA665752) in both the sampled drugs, a result that is in good agreement with the results of previous conventional experiments using 96 well plates.  相似文献   

5.
The present study shows the influence of two different electron beam deflection techniques on surface deformation, microstructure and hardness after an electron beam surface remelting of a spray‐formed hypereutectic aluminium alloy (AlSi17Fe5Cu4Mg). Due to the specific rapid heating and cooling rates on the one hand and the high content of alloying elements on the other hand, the surface microstructure was modified by phase formation, grain refinement and an oversaturation of aluminium solid solution. As a result the hardness was threefold increased (284 HV 0.1) compared to the untreated base material (104 HV 0.1). This hardness increase was significantly higher than the level of the conventional heat treatment (e. g. age hardening approx. 170 HV 0.1). The remelting process largely influenced the wear behaviour under abrasive (scratch test) and abrasive‐adhesive (pin‐on‐disc test) load conditions. Remelted surface layers generated by meander deflection technique showed the most improvement regarding their wear performance.  相似文献   

6.
A new method based on the atomic force microscope has been developed to measure the lateral flexibility of single wood pulp fibres. In this method, individual wet pulp fibres from earlywood and latewood of Pinus radiata were placed on a newly designed two-point support, and the load and the deflection of fibres were measured under three-point bending test using a modified cantilever probe. The lateral flexibility values of the fibres were then calculated using propped cantilever beam theory. The results obtained indicate that earlywood fibres are substantially more flexible, and have a greater range of flexibility values than latewood fibres.  相似文献   

7.
Shaft fatigue testing involves long test times (~3 months), high energy consumption and high test equipment maintenance costs owing to the high bending and twisting moments required (~1600 Nm), high number of cycles (~107) and large sample sizes (~30). To reduce testing time, we designed, manufactured and evaluated a resonant plate test bench. Using finite element analysis and topological optimization, we redesigned the traditional resonant flat plates for higher resonant frequency and lower deflection at the plate free ends. We found that the optimal topology is an I‐beam; it doubles the frequency of flexion tests, up to 100 Hz, and exhibits 2 mm of deflection under a load of 1 kN. To measure the moments induced on the shaft sample during testing, we measured the surface deflection of the resonant plates. Tests on a calibration axle showed that the induced shaft moment has very high linear correlation (R2 > 0.99) with the plate's surface deformation. We used our test bench to evaluate fatigue resistance for a type of crankshaft manufactured by a local company. We found that their fatigue resistance limit was 1250 Nm at 107 cycles and that their mean useful life was 104 cycles when they are subjected to a 1400 Nm moment. These results agree with previous results on this type of crankshaft using other methods.  相似文献   

8.
Interfacial fracture toughness measurements of thin film-substrate systems are of importance in many applications. In the microelectronics industry, the interfacial adhesion between the dielectric-barrier-metal layers on a semiconductor chip is critical for chip reliability. In this paper, we propose a thermally-driven patterned buckling delamination test that does not use a pre-existing weak interface. The test relies on causing a patterned film to debond from its substrate by inducing a compressive stress due to heating of the film on a thick silicon substrate. The compressive stress causes the film to buckle and debond from the substrate. A model for the propagation of the buckling-induced debond is then developed to estimate interfacial fracture toughness. The efficacy of the thermally-driven buckling test is demonstrated on a model Al/SU8/Si film-substrate system wherein the Al film debonds along its interface to SU8. The interfacial toughness of the Al/SU8 interface is estimated using the proposed test and is compared to the toughness for the same system obtained using an alternative test with a weakened interface to validate the developed elastic-plastic model for buckling-induced debond propagation.  相似文献   

9.
Nemoto S  Tsuchiya M 《Applied optics》2005,44(25):5215-5223
A low-loss deflection prism for a laser beam is proposed, and its various characteristics such as beam quality, transmittance, deflection angle, and polarization state are presented. The prism having a trapezoidal form is made from BK7 glass and is designed for a He-Ne laser beam. When a p-polarized beam is incident on the slant surface of the prism at the Brewster angle, the totally reflected and transmitted beam is deflected by 90 degrees, and the measured transmittance is nearly 98%. The theoretical transmittances of the proposed prism are compared with those of a Pellin-Broca prism.  相似文献   

10.
In ordinary oscilloscopes, the brilliance of the trace depends strongly on the deflection speed of the beam. With the circuit described here, a uniform optimal brightness of the oscillograms is obtained independently of the shape of the curve and the frequency of repetition. Thus even steep slopes are well visible from a distance, and manual adjustment of the brightness becomes superfluous. This is especially important in lecture demonstrations. A protective circuit limits the cathode current so that a standing beam cannot burn out the screen. The circuits were designed for large color picture tubes, but they are also suitable, in a simplified form, for improving monochromatic oscilloscopes [1]. In lage picture tubes, the relation between the beam deflection and the deflection currents is not linear. The resulting distortions on the screen call for proper correction signals. These while depending on x- and y-beam positions, must not be influenced by the deflection frequency.  相似文献   

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