Study on the Preparation Technology of CuO Nanometric Powders by Homogeneous Precipitation in High Intensity Ultrasonic Field

2009 ◽  
Vol 79-82 ◽  
pp. 325-328
Author(s):  
Guang Li ◽  
Cheng Wen Chai
Keyword(s):  
High Intensity ◽  
Ultrasonic Field ◽  
Homogeneous Precipitation ◽  
Preparation Technology ◽  
Reaction Velocity ◽  
Ultrasound Field ◽  
Intensity Field ◽  
Speed Up ◽  
Partical Size ◽  
Xrd And Tem

Nanopowder CuO was prepared by a new method which involves homogeneous precipitation in high intensity field, and powder so obtained was examined by XRD and TEM. The mechanism and effects of conditions of treatment on process and final products are also discussed. These results indicate that not only the reaction velocity was speed up dramatically under ultrasound field but also the particle size of production was greatly affected by the intensity of ultrasound field, the greater the ultrasound field, the smaller the partical size.

High Intensity Focused Ultrasound (HIFU) Transducer Characterization Using Acoustic Streaming

2007 ◽  
Author(s):  
Prasanna Hariharan ◽  
Ronald A. Robinson ◽  
Matthew R. Myers ◽  
Rupak K. Banerjee
Keyword(s):  
High Intensity ◽  
Focused Ultrasound ◽  
Optical Measurement ◽  
Measurement Techniques ◽  
Acoustic Streaming ◽  
Acoustic Power ◽  
High Intensity Focused Ultrasound ◽  
Medical Ultrasound ◽  
Intensity Field ◽  
Streaming Velocity

A new, non-perturbing optical measurement technique was developed to characterize medical ultrasound fields generated by High Intensity Focused Ultrasound (HIFU) transducers using a phenomenon called ‘acoustic streaming’. The acoustic streaming velocity generated by HIFU transducers was measured experimentally using Digital Particle Image Velocimetry (DPIV). The streaming velocity was then calculated numerically using the finite-element method. An optimization algorithm was developed to back-calculate acoustic power and intensity field by minimizing the difference between experimental and numerical streaming velocities. The intensity field and acoustic power calculated using this approach was validated with standard measurement techniques. Results showed that the inverse method was able to predict acoustic power and intensity fields within 10% of the actual value measured using standard techniques, at the low powers where standard methods can be safely applied. This technique is also potentially useful for evaluating medical ultrasound transducers at the higher power levels used in clinical practice.

scholarly journals Single-Molecule Detection of DNA in a Nanochannel by High-Field Strength-Assisted Electrical Impedance Spectroscopy

Micromachines ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 189 ◽  
Author(s):  
Porpin Pungetmongkol ◽  
Takatoki Yamamoto
Keyword(s):  
Single Molecule ◽  
High Intensity ◽  
High Sensitivity ◽  
Electrical Impedance Spectroscopy ◽  
Random Coil ◽  
Label Free ◽  
Electrode Gap ◽  
Label Free Detection ◽  
Intensity Field ◽  
Nanogap Electrodes

Many researchers have fabricated micro and nanofluidic devices incorporating optical, chemical, and electrical detection systems with the aim of achieving on-chip analysis of macromolecules. The present study demonstrates a label-free detection of DNA using a nanofluidic device based on impedance measurements that is both sensitive and simple to operate. Using this device, the electrophoresis and dielectrophoresis effect on DNA conformation and the length dependence were examined. A low alternating voltage was applied to the nanogap electrodes to generate a high intensity field (>0.5 MV/m) under non-faradaic conditions. In addition, a 100 nm thick gold electrode was completely embedded in the substrate to allow direct measurements of a solution containing the sample passing through the gap, without any surface modification required. The high intensity field in this device produced a dielectrophoretic force that stretched the DNA molecule across the electrode gap at a specific frequency, based on back and forth movements between the electrodes with the DNA in a random coil conformation. The characteristics of 100 bp, 500 bp, 1 kbp, 5 kbp, 10 kbp, and 48 kbp λ DNA associated with various conformations were quantitatively analyzed with high resolution (on the femtomolar level). The sensitivity of this system was found to be more than about 10 orders of magnitude higher than that obtained from conventional linear alternating current (AC) impedance for the analysis of bio-polymers. This new high-sensitivity process is expected to be advantageous with regard to the study of complex macromolecules and nanoparticles.

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