HeLa cell transfection using a novel sonoporation system

Sonoporation has been shown to have an important role in biotechnology for gene therapy and drug delivery. This paper presents a novel microfluidic sonoporation system that achieves high rates of cell transfection and cell viability by operating the sonoporation chamber at resonance. The paper presents a theoretical analysis of the resonant sonoporation chamber design, which achieves sonoporation by forming an ultrasonic standing wave across the chamber. A piezoelectric transducer (PZT 26) is used to generate the ultrasound and the different material thicknesses have been identified to give a chamber resonance at 980 kHz. The efficiency of the sonoporation system was determined experimentally under a range of sonoporation conditions and different exposures time (5, 10, 15, and 20 s, respectively) using HeLa cells and plasmid (peGFP-N1). The experimental results achieve a cell transfection efficiency of 68.9% (analysis of variance, ANOVA, p < 0.05) at the resonant frequency of 980 kHz at 100 V(p-p) (19.5 MPa) with a cell viability of 77% after 10 s of insonication.     

控制器局域网(CAN)的原理及其实施

CAN总线(控制器局域网)是适用于多数以CAN与ISO 11898作为物理层的理想的高级工业协议。其成本、性能及可升级性都为系统设计提供了极大的灵活性;LIN总线(局域互联网络)是一种低成本的新型串行通信系统,适用于汽车中的分布式电子控制系统,完善了现有的各种汽车多路网络。从本期开始,我们将精选部分有关CAN／LIN的技术文章,连续刊登在“CAN／LIN专栏”中,供广大读者参考。     

在数字调制系统中进行精确的非线性测量

随着日益增加的智能手机和无线互联网3G覆盖范围以及4G系统即将引入带来的持续压力,数字通信射频组件的设计活动越来越丰富。设计活动的前沿在于功率放大器（PA）的开发。PA设计工程师面对的首要问题是功率所增加的效率（PAE）。高PAE意味着：     

Local oscillator chain for 1.55 to 1.75THz with 100-/spl mu/W peak power

We report on the design and performance of a fix-tuned /spl times/2/spl times/3/spl times/3 frequency multiplier chain that covers 1.55-1.75THz. The chain is nominally pumped with 100mW at W-band. At 120K the measured output power is larger than 4/spl mu/W across the band with a peak power of 100/spl mu/W at 1.665THz. A similar chain operated at room temperature produced a peak power of 21/spl mu/W. These power levels now make it possible to deploy multipixel heterodyne imaging arrays in this frequency range.     

An All-Fiber Coupled Multicolor Microspherical Light Source

We present results on the realization of an all-taper coupled, multicolor microspherical light source fabricated from the erbium-doped fluoride glass ZBLALiP. Whispering gallery mode lasing at 1555 nm and fluorescent emissions from the ultraviolet to the infrared (IR) have been observed. A tapered fiber is used to launch 980-nm pump light into the microresonator cavity and to collect the resulting IR lasing. A separate, half-taper fiber is used to outcouple the upconversion spectrum over several hundred nanometers. A number of discrete emissions from 400 to 850 nm have been observed in the upconversion spectrum, indicating the suitability of this scheme as a miniature device with a 450-nm-wide band and reasonable output coupling efficiency.     

Potential GPRS 900/180-MHz and WCDMA 1900-MHz interference to medical devices

This study compared the potential for interference to medical devices from radio frequency (RF) fields radiated by GSM 900/1800-MHz, general packet radio service (GPRS) 900/1800-MHz, and wideband code division multiple access (WCDMA) 1900-MHz handsets. The study used a balanced half-wave dipole antenna, which was energized with a signal at the standard power level for each technology, and then brought towards the medical device while noting the distance at which interference became apparent. Additional testing was performed with signals that comply with the requirements of the international immunity standard to RF fields, IEC 61000-4-3. The testing provides a sense of the overall interference impact that GPRS and WCDMA (frequency division duplex) may have, relative to current mobile technologies, and to the internationally recognized standard for radiated RF immunity. Ten medical devices were tested: two pulse oximeters, a blood pressure monitor, a patient monitor, a humidifier, three models of cardiac defibrillator, and two models of infusion pump. Our conclusion from this and a related study on consumer devices is that WCDMA handsets are unlikely to be a significant interference threat to medical electronics at typical separation distances.     

A 21-mW 8-b 125-MSample/s ADC in 0.09-mm/sup 2/ 0.13-/spl mu/m CMOS

This paper presents an 8-b two-step subranging analog-to-digital (ADC) using interpolation, averaging, offset compensation, and pipelining techniques to accomplish an effective number of bits of 7.6 b at 125 MSample/s. The 0.13-/spl mu/m CMOS ADC occupies 0.09 mm/sup 2/ and consumes 21 mW.     

On the effect of pavement microtexture on thin film traction

The descent of a tread element of a tire rolling on a pavement on which a thin viscous fluid film is present is modeled. The tread element is assumed to be flat or curved and the pavement is assumed to possess a microtexture. Asymptotic results for the load supported by the tread element and the descent time are derived for different texture patterns. It is shown that the texture pattern as well as amplitude can significantly change the performance from that predicted by a smooth pavement assumption.     

Mathematical modelling of quasi-resonant converters

A method to determine the small-signal control-to-output transfer function of quasi-resonant converters operating with continuous current is presented. The design of the feedback loop and compensation network becomes easier by this approach. Investigation is carried out using the boost converter topology