This paper describes the design and fabrication of fiber-optic nanoprobes developed for optical detection in single living
cells. It is critical to fabricate probes with well-controlled nanoapertures for optimized spatial resolution and optical
transmission. The detection sensitivity of fiber-optic nanoprobe depends mainly on the extremely small excitation volume that
is determined by the aperture sizes and penetration depths. We investigate the angle dependence of the aperture in shadow
evaporation of the metal coating onto the tip wall. It was found that nanoaperture diameters of approximately 50 nm can be
achieved using a 25° tilt angle. On the other hand, the aperture size is sensitive to the subtle change of the metal evaporation
angle and could be blocked by irregular metal grains. Through focused ion beam (FIB) milling, optical nanoprobes with well-defined
aperture size as small as 200 nm can be obtained. Finally, we illustrate the use of the nanoprobes by detecting a fluorescent
species, benzo[a]pyrene tetrol (BPT), in single living cells. A quantitative estimation of the numbers of BPT molecules detected
using fiber-optic nanoprobes for BPT solutions shows that the limit of detection was approximately 100 molecules. 相似文献
The high rate of charge trapping in thin-film silicon nitride causes its electrical properties to change with stressing level
and time. The rate of shift of the high-frequency CV curves of Al/SiNxHy/cSi capacitors was used here to measure nitride charging rate and to compare PECVD nitrides deposited under various conditions
of plasma power and gas mixture in the same parallel-plate reactor. By operating the plasma under high power to activate the
NH3 or N2 and under low SiH4 flow to ensure that all of the SiH4 reacts with N, it is possible to deposit N-rich nitride that has no detectable Si—H bonding,
which bonding others have correlated with charge trapping. Nitride deposited under these conditions using NH3 and 13 MHz rf power had charging rates for both gate polarities that were 20 times lower than those of nitride that had a
“stoichiometric” N/Si ratio of 4/3 and that had its H distributed among Si—H and N—H bonds. MIS capacitors made with the latter
nitride also had a high negative initial flat-bond voltage, indicating the presence of grown-in positive charge. This charge
was large enough to invert the surface ofp-Si substrates. N-rich nitride free of Si—H that was deposited either using N2 or using low-frequency rf power (≤400 kHz) had higher charging rates than did that deposited from NH3 at 13 MHz. Also, the low-frequency material contained grown-in positive charge that is attributed to H+ implanted by the high ion bombardment energy of the low-frequency plasma. 相似文献
For micro-gyroscopes, the angular rate detection components have to oscillate forwards and backwards alternatively. An innovative design of micro-electromagnetic drive module is proposed to make a Π-type thin disc reciprocally and efficiently rotate within a certain of angular interval. Twelve EM (Electromagnetic) poles, with iron cores at the center and wound by electroplated copper wires, enclosing the thin disc are designed to provide the magnetic drive power. Isotropic etching technique is employed to fabricate the high-aspect-ratio trench, housing of the follow-up electroplated copper, so that the contact angle of wire against trench can be increased and the potential defect of cavities and pores within the wire can be prevented. On the other hand, a Π-type thin disc, with a central bearing and a set of auxiliary bushing, is designed to conduct the pitch motion as an angular excitation, in addition to spinning, is exerted on the gyroscope. That is, the angular motion of the disc is two-dimensional: spinning, driven by the EM poles, and tilting, to respond to the exerted angular rate due to Coriolis effect.The efficacy of the micro-magnetic drive module is verified by theoretical analysis and computer simulations by the commercial software, Ansoft Maxewll. In comparison with the conventional planar windings in micro-scale systems, the magnetic drive force is increased by 150%. 相似文献
We have developed a palladium(0)‐catalyzed tandem process which involves the cross‐coupling reaction of N‐tosylhydrazones with dibromide compounds followed by a sequence of intramolecular 5‐exo‐trig, 3‐exo‐trig cyclization, ring opening, and β‐hydride elimination to produce 6‐endo‐trig cyclized products. The strategy was successfully applied for the regioselective synthesis of substituted benzo[b]naphtho[2,1‐d]thiophenes, naphtho[1,2‐b]benzofurans, and benzo[a]carbazoles in moderate to excellent yields.
Topics in Catalysis - CO2 reforming of methanol for producing hydrogen was experimentally carried out in a fixed-bed reactor on 10%Ni/SiO2. The 10%Ni/SiO2 was completely reduced during H2... 相似文献