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排序方式: 共有207条查询结果,搜索用时 31 毫秒
201.
Kilic O Digonnet MJ Kino GS Solgaard O 《The Journal of the Acoustical Society of America》2011,129(4):1837-1850
This work reports on an optical hydrophone that is insensitive to hydrostatic pressure, yet capable of measuring acoustic pressures as low as the background noise in the ocean in a frequency range of 1 Hz to 100 kHz. The miniature hydrophone consists of a Fabry-Perot interferometer made of a photonic-crystal reflector interrogated with a single-mode fiber and is compatible with existing fiber-optic technologies. Three sensors with different acoustic power ranges placed within a sub-wavelength sized hydrophone head allow a high dynamic range in the excess of 160 dB with a low harmonic distortion of better than -30 dB. A method for suppressing cross-coupling between sensors in the same hydrophone head is also proposed. A prototype was fabricated, assembled, and tested. The sensitivity was measured from 100 Hz to 100 kHz, demonstrating a sound-pressure-equivalent noise spectral density down to 12 μPa/Hz(1/2), a flatband wider than 10 kHz, and very low distortion. 相似文献
202.
Skála T Tsud N Orti MÁ Menteş TO Locatelli A Prince KC Matolín V 《Physical chemistry chemical physics : PCCP》2011,13(15):7083-7089
The deposition of ceria on a preoxidized W(110) crystal at 870 K has been studied in situ by photoelectron spectroscopy and low-energy electron diffraction. Formation of an epitaxial layer of crystalline cerium tungstate Ce(6)WO(12)(100), with the metals in the Ce(3+) and W(6+) chemical states, has been observed. The interface between the tungsten substrate and the tungstate film consists of WO suboxide. At thicknesses above 0.89 nm, cerium dioxide grows on the surface of Ce(6)WO(12), favoured by the limited diffusion of tungsten from the substrate. 相似文献
203.
Holographic pixel super-resolution in portable lensless on-chip microscopy using a fiber-optic array
Bishara W Sikora U Mudanyali O Su TW Yaglidere O Luckhart S Ozcan A 《Lab on a chip》2011,11(7):1276-1279
We report a portable lensless on-chip microscope that can achieve <1 μm resolution over a wide field-of-view of ~ 24 mm(2) without the use of any mechanical scanning. This compact on-chip microscope weighs ~ 95 g and is based on partially coherent digital in-line holography. Multiple fiber-optic waveguides are butt-coupled to light emitting diodes, which are controlled by a low-cost micro-controller to sequentially illuminate the sample. The resulting lensfree holograms are then captured by a digital sensor-array and are rapidly processed using a pixel super-resolution algorithm to generate much higher resolution holographic images (both phase and amplitude) of the objects. This wide-field and high-resolution on-chip microscope, being compact and light-weight, would be important for global health problems such as diagnosis of infectious diseases in remote locations. Toward this end, we validate the performance of this field-portable microscope by imaging human malaria parasites (Plasmodium falciparum) in thin blood smears. Our results constitute the first-time that a lensfree on-chip microscope has successfully imaged malaria parasites. 相似文献
204.
Wang S Zhao X Khimji I Akbas R Qiu W Edwards D Cramer DW Ye B Demirci U 《Lab on a chip》2011,11(20):3411-3418
Ovarian cancer is asymptomatic in the early stages and most patients present with advanced levels of disease. The lack of cost-effective methods that can achieve frequent, simple and non-invasive testing hinders early detection and causes high mortality in ovarian cancer patients. Here, we report a simple and inexpensive microchip ELISA-based detection module that employs a portable detection system, i.e., a cell phone/charge-coupled device (CCD) to quantify an ovarian cancer biomarker, HE4, in urine. Integration of a mobile application with a cell phone enabled immediate processing of microchip ELISA results, which eliminated the need for a bulky, expensive spectrophotometer. The HE4 level detected by a cell phone or a lensless CCD system was significantly elevated in urine samples from cancer patients (n = 19) than healthy controls (n = 20) (p < 0.001). Receiver operating characteristic (ROC) analyses showed that the microchip ELISA coupled with a cell phone running an automated analysis mobile application had a sensitivity of 89.5% at a specificity of 90%. Under the same specificity, the microchip ELISA coupled with a CCD had a sensitivity of 84.2%. In conclusion, integration of microchip ELISA with cell phone/CCD-based colorimetric measurement technology can be used to detect HE4 biomarker at the point-of-care (POC), paving the way to create bedside technologies for diagnostics and treatment monitoring. 相似文献
205.
In this study, steady-state laminar forced flow and heat transfer in a horizontal smooth trapezoidal duct having different corner angles were experimentally investigated in the Reynolds number range from 102 to 103. Flow is hydrodynamically fully developed and thermally developing under a uniform surface temperature condition. Based on the present experimental data of laminar flow in the thermal entrance region, new engineering correlations were presented for the heat transfer and friction coefficients for each corner angle. The results have shown that as the Reynolds number increases heat transfer coefficient increases but Darcy friction factor decreases. Also, it is observed that average Nusselt number increases while average Darcy friction factor decreases with increasing corner angle of the duct. 相似文献
206.
Cai Z Riedel H Thaw Saw NM Kütük O Mewis I Jäger H Knorr D Smetanska I 《Applied biochemistry and biotechnology》2011,164(4):443-453
Plant cell cultures provide a large potential for the production of secondary metabolites. Through the application of different
physical and chemical cell stress factors, we investigated the production of the secondary metabolites in plant cell cultures.
The effects of pulsed electric field (PEF) and ethephon on growth and secondary metabolism, particularly anthocyanins and
phenolic acids synthesis, were investigated by using suspension culture of Vitis vinifera L. cv. Gamay Fréaux as a model system. Anthocyanins were measured by spectrophotometer and extracellular phenolic acids were
determined by high-performance liquid chromatography. The compounds were identified by liquid chromatography–mass spectrometry
and nuclear magnetic resonance. After the treatments with PEF and ethephon, the concentrations of anthocyanins and phenolic
acids in cell culture were higher than in the control, without loss of biomass. The combination of PEF treatment and ethephon
improved secondary metabolites formation. Production levels of extracellular phenolic acids, 3-O-glucosyl-resveratrol were increased by PEF and ethephon treatments. The results show that PEF induced a defense response
of plant cells and may have altered the cell/membrane’s dielectric properties. PEF, an external stimulus or stress, is proposed
as a promising new abiotic elicitor for stimulating secondary metabolites biosynthesis in plant cell cultures. 相似文献
207.
Öztürk Tuğçe Pınar Gelir Ali Keshtiban Nahid Aghabalapoor Yargı Önder Özdemir Onur B. Mucur Selin Pıravadılı Seçgin Alper 《Journal of Solid State Electrochemistry》2023,27(4):885-894
Journal of Solid State Electrochemistry - The motion of the ion pairs under the applied electric field is an important phenomenon in the storage properties of the capacitive devices. In this study,... 相似文献