Extraction of genomic DNA and detection of single nucleotide polymorphism genotyping utilizing an integrated magnetic bead-based microfluidic platform

This study presents a new magnetic bead-based microfluidic platform, which integrates three major modules for rapid leukocytes purification, genomic DNA (gDNA) extraction and fast analysis of genetic gene. By utilizing microfluidic technologies and magnetic beads conjugated with CD_15/45 antibodies, leukocytes in a human whole blood sample can be first purified and concentrated, followed by extraction of gDNA utilizing surface-charge switchable, DNA-specific, magnetic beads in the lysis solution. Then, specific genes associated with genetic diseases can be amplified by an on-chip polymerase chain reaction (PCR) process automatically. The whole pretreatment process including the leukocytes purification and gDNA extraction can be performed in an automatic fashion with the incorporation of the built bio-separators consisting of microcoils array within less than 20 min. The detection of single nucleotide polymorphism (SNP) genotyping of methylenetetra-hydrofolate reductase (MTHFR) C677T region associated with an increased risk of genetic diseases was further performed to demonstrate the capability of the proposed system. The extracted gDNA can be transported into a micro PCR chamber for on-chip fast nucleic acid amplification of detection genes with minimum human intervention. Hence, the developed system may provide a powerful automated platform for pretreatment of human leukocytes, gDNA extraction and fast analysis of genetic gene.     

Architectural design and FPGA implementation of radix-4 CORDIC processor

A new scaled radix-4 CORDIC architecture that incorporates pipelining and parallelism is presented. The latency of the architecture is n/2 clock cycles and throughput rate is one valid result per n/2 clocks for n bit precision. A 16 bit radix-4 CORDIC architecture is implemented on the available FPGA platform. The corresponding latency of the architecture is eight clock cycles and throughput rate is one valid result per eight clock cycles. The entire scaled architecture operates at 56.96 MHz of clock rate with a power consumption of 380 mW. The speed can be enhanced with the upgraded version of FPGA device. A speed-area optimized processor is obtained through this architecture and is suitable for real time applications.     

Nano-texturing of magnetic recording sliders via laser ablation

To increase the storage density of hard disk drives, the flying height of the slider needs to be reduced to <10 nm. This requires super-smooth surfaces of the disk and slider. As the roughness decreases, stiction and adhesion are found to increase substantially leading to failures of the head/disk interface. Texturing the slider surface is a well-known approach to this issue. In this study we investigated laser ablation as a potential process for texturing magnetic recording sliders. It was found that straight laser machining caused unwanted re-deposition of material. These deposits could be significantly reduced by using a chemical etching enhanced laser process.     

A pneumatic micropump incorporated with a normally closed valve capable of generating a high pumping rate and a high back pressure

This study reports on a new pneumatic micropump integrated with a normally closed valve that is capable of generating a high pumping rate and a high back pressure. The micropump consists of a sample flow microchannel, three underlying pneumatic air chambers, resilient polydimethylsiloxane (PDMS) membrane structures and a normally closed valve. The normally closed valve of the micropump is a PDMS-based floating block structure located inside the sample flow microchannel, which is activated by hydraulic pressure created by the peristaltic motion of the PDMS membranes. The valve is used to effectively increase pumping rates and back pressures since it is utilized to prevent backflow. Experimental results indicate that a pumping rate as high as 900 μL/min at a driving frequency of 90 Hz and at an applied pressure of 20 psi (1.378 × 10⁵ Nt/m²) can be obtained. The back pressure on the micropump can be as high as 85 cm-H₂O (8,610.5 Nt/m²) at the same operation conditions. The micropump is fabricated by soft lithography processes and can be easily integrated with other microfluidic devices. To demonstrate its capability to prevent cross contamination during chemical analysis applications, two micropumps and a V-shape channel are integrated to perform a titration of two chemical solutions, specifically sodium hydroxide (NaOH) and benzoic acid (C₆H₅COOH). Experimental data show that mixing with a pH value ranging from 2.8 to 12.3 can be successfully titrated. The development of this micropump can be a promising approach for further biomedical and chemical analysis applications.     

Influence of ammonia concentration on the microstructure,electrical and raman properties of low temperature chemical bath deposited ZnO nanorods

Nanostructured zinc oxide synthesized using an easy and low temperature chemical bath deposition method are among the most promising low cost semiconducting nanostructures investigated for a variety of applications. We successfully report the effects of ammonia solution in the growth of ZnO nanorods at a temperature of 60 °C. Successive addition of ammonia altered the degree of supersaturation of the growth solution, causing a significant deviation in the morphology and crystal orientation of ZnO nanorods. Field emission scanning Electron Microscopy images revealed changes in surface morphology of ZnO nanorods with respect to addition of specific amounts of ammonia. X-ray diffraction analysis revealed wurtzite crystal structure of ZnO which was further supported by X-ray photoelectron studies, optical absorbance and Raman spectra that also revealed the existence of wurtzite ZnO. The current-voltage measurement showed the electrical properties of the synthesized ZnO nanorods. The vertically grown nanorods with flat tops, effect more rectifying Schottky contacts to be realized on comparison to needle like structures.     

Environmentally Adaptive Polymer Hydrogels: Maintaining Wet-Soft Features in Extreme Conditions

Hydrogels have been widely explored to adapt to different application circumstances. As typical wet-soft materials, the high-water content of hydrogels is beneficial to their wide biomedical applications. Moreover, hydrogels have been displaying considerable application potential in some high-tech areas, like brain-computer interface, intelligent actuator, flexible sensor, etc. However, traditional hydrogel is susceptive to freezing below zero, dehydration, performance swelling-induced deformation, and suffers from mechanical damage in extremely mechanical environments, which result in the loss of wet-soft peculiarities (e.g., flexibility, structure integrity, transparency), greatly limiting their applications. Therefore, reducing the freezing point, improving the dehydration/solution resistance, and designing mechanical adaptability are effective strategies to endow hydrogels with the extreme environmental adaptability, thus broadening their application fields. This review systematically summarizes research advances of environmentally adaptive hydrogels (EAHs), comprising anti-freezing, dehydration-resistant, acid/base/swelling deformation-resistant, and mechanical environment adaptive hydrogels (MEAHs). Firstly, fabrication methods are presented, including the deep eutectic solvent/ionic liquid substituent, the addition of salts, organogel, polymer network modification, and double network (DN) complex/nanocomposite strategy, etc. Meanwhile, the features of different approaches are overviewed. The mechanisms, properties, and applications (e.g., intelligent actuator, wound dressing, flexible sensor) of EAHs are demonstrated. Finally, the issues and future perspectives for EAHs’ researches are demonstrated.     

In Vivo Photoacoustic Imaging of Livers Using Biodegradable Hyaluronic Acid‐Conjugated Silica Nanoparticles

The diagnosis of liver diseases is generally carried out via ultrasound imaging, computed tomography, and magnetic resonance imaging. The emerging photoacoustic imaging is an attractive alternative to diagnose even early stage of liver diseases providing high‐resolution anatomical and functional information in deep tissue noninvasively. However, the liver has insufficient photoacoustic contrast due to low optical absorbance in the near‐infrared windows. Here, a new hyaluronate–silica nanoparticle (HA–SiNP) conjugate for liver‐specific delivery and imaging for the diagnosis of liver diseases is developed. The HA–SiNP conjugates show high liver‐specific targeting efficiency, strong optical absorbance near‐infrared windows, excellent biocompatibility, and biodegradability. The liver‐specific targeting efficiency is verified by in vitro cellular uptake test, and in vivo and ex vivo photoacoustic imaging. In vivo photoacoustic imaging shows that photoacoustic amplitude in the liver injected with HA–SiNP conjugates is 4.4 times higher than that of the liver injected with SiNP. The biocompatibility and biodegradability of HA–SiNP conjugates are verified by cell viability test, optical spectrum analysis of urine, and inductively coupled plasma‐mass spectroscopy (ICP‐MS) analysis. Taken together, HA–SiNP conjugates may be developed as a promising liver targeted photoacoustic imaging contrast agent and liver‐targeted drug delivery agent.     

基于PIC16F877A的永磁无刷直流电机的控制器设计

随着科技的发展,对无刷直流电动机的性能提出更高的要求.本文在研究无刷直流电动机数学模型、导通方式的基础上,以单片机PIC16F877A为核心设计控制系统硬件电路和软件程序,硬件电路包括电机转子位置检测电路、PIC16F877A最小系统、转子位置检测电路、IGBT驱动保护电路和系统信息反馈电路,并利用MPLAB软件编译平台编写控制系统软件程序.通过对实验结果的分析：可知本文所设计的控制系统性能可靠、结构简单,能够实现对无刷直流电机的可靠控制.