Hironao Okada

Association of increased pathogenicity of Asian H5N1 highly pathogenic avian influenza viruses in chickens with highly efficient viral replication accompanied by early destruction of innate immune responses.

ABSTRACT The Asian H5N1 highly pathogenic avian influenza (HPAI) viruses have been increasing in pathogenicity in diverse avian species since 1996 and are now widespread in Asian, European, and African countries. To better understand the basis of the increased pathogenicity of recent Asian H5N1 HPAI viruses in chickens, we compared the fevers and mean death times (MDTs) of chickens infected with the Asian H5N1 A/chicken/Yamaguchi/7/04 (CkYM7) strain with those infected with the H5N1 Duck/Yokohama/aq10/03 (DkYK10) strain, using a wireless thermosensor. Asian H5N1 CkYM7 caused peracute death in chickens before fever could be induced, whereas DkYK10 virus induced high fevers and had a long MDT. Real-time PCR analyses of cytokine mRNA expressions showed that CkYM7 quickly induced antiviral and proinflammatory cytokine mRNA expressions at 24 h postinfection (hpi) that suddenly decreased at 32 hpi. In contrast, these cytokine mRNA expressions increased at 24 hpi in the DkYK10 group, but decreased from 48 hpi onward to levels similar to those resulting from infection with the low-pathogenicity H5N2 A/chicken/Ibaraki/1/2004 strain. Sequential titrations of viruses in lungs, spleens, and kidneys demonstrated that CkYM7 replicated rapidly and efficiently in infected chickens and that the viral titers were more than twofold higher than those of DkYK10. CkYM7 preferentially and efficiently replicated in macrophages and vascular endothelial cells, while DkYK10 grew moderately in macrophages. These results indicate that the increased pathogenicity in chickens of the recent Asian H5N1 HPAI viruses may be associated with extremely rapid and high replication of the virus in macrophages and vascular endothelial cells, which resulted in disruption of the thermoregulation system and innate immune responses.

Wafer Level Surface Activated Bonding Tool for MEMS Packaging

A wafer level surface activated bonding (SAB) tool has been developed for microelectromechanical systems (MEMS) packaging at low temperature. The tool accommodates 8 in. diam wafers. The principle features of the tool are the automatic parallel adjustment for 8 in. wafers to a margin of error within ± 1 μm and the X, Y, and θ axis alignments with an accuracy of ±0.5 μm. We have approached a new integration technique for the integration of ionic crystals with transparent and nontransparent thin intermediate layers using this tool. Various sizes of patterned and bare silicon, Al silicate glass, and quartz wafers cleaned by a low energy argon ion source in a vacuum have been successfully bonded by this technique at low temperature. Radioisotope fine leak and vacuum seal tests of sealed silicon cavities show leak rates of 1.0 X 10 -9 and 2.6 X 10 -16 Pa/m 3 s, respectively, which are lower than the American military standard encapsulation requirements for MEMS devices in harsh environments. Void-free interfaces with bonding strengths comparable to bulk materials are found. Low adhesion between SAB-processed ionic crystals without adhesive layers is believed to be due to radiation-induced discontinuous polarization.

Room temperature vacuum sealing using surface activated bonding method

We have demonstrated that room temperature bonding of Si/Si and Si/Cu using surface activated bonding (SAB) method could be successfully applied to vacuum sealing of microcavities. This method will make it possible to seal various MEMS devices on silicon or non-silicon substrates in vacuum by bonding of silicon cap wafers, because the method can be applied to diverse combinations of materials including silicon, metal films and compound semiconductors. In addition, the SAB vacuum sealing can overcome the problem that the sealed cavity pressure increases during heating due to the accumulation of gaseous products originating at the bonding interface. In this study, the quality of vacuum sealing by SAB is examined by estimating the pressure of the sealed cavity; for that, resonant quality factors of microcanti-levers placed in the vacuum-sealed cavity are measured. As a result, the cavities sealed with Si/Si bonding have a good sealing quality with the pressure increase rate of around 2/spl times/10/sup -15/ Pa m/sup 3//sec and their pressure is being maintained at less than 3 Pa. Also, it has been found that the pressure increase rate of Si/Cu sealing is larger than that of Si/Si sealing and is estimated as about 2/spl times/10/sup -14/ Pa m/sup 3//sec.

NP Body Domain and PB2 Contribute to Increased Virulence of H5N1 Highly Pathogenic Avian Influenza Viruses in Chickens

ABSTRACT The molecular basis of pathogenicity of H5N1 highly pathogenic avian influenza (HPAI) viruses in chickens remains largely unknown. H5N1 A/chicken/Yamaguchi/7/2004 virus (CkYM7) replicates rapidly in macrophages and vascular endothelial cells in chickens, causing sudden death without fever or gross lesions, while H5N1 A/duck/Yokohama/aq10/2003 virus (DkYK10) induces high fever, severe gross lesions, and a prolonged time to death, despite the 98% amino acid identity between the two viruses. To explore the molecular basis of this difference in pathogenicity, a series of eight single-gene reassortant viruses from these HPAI viruses were compared for pathogenicity in chickens. Two reassortants possessing the NP or PB2 gene from DkYK10 in the CkYM7 background reduced pathogenicity compared to other reassortants or CkYM7. Inversely, reassortants possessing the NP or PB2 gene of CkYM7 in the DkYK10 background (rgDkYK-PB2Ck, rgDkYK-NPCk) replicated quickly and reached higher titers than DkYK10, accompanied by more rapid and frequent apoptosis of macrophages. The rgDkYK-NPCk and rgDkYK-PB2Ck reassortants also replicated more rapidly in chicken embryo fibroblasts (CEFs) than did rgDkYK10, but replication of these viruses was similar to that of CkYM7 and DkYK10 in duck embryo fibroblasts. A comparison of pathogenicities of seven rgDkYK10 mutants with a single amino acid substitution in NPDk demonstrated that valine at position 105 in the NPCk was responsible for the increased pathogenicity in chickens. NPCk, NP105V, and PB2Ck enhanced the polymerase activity of DkYK10 in CEFs. These results indicate that both NP and PB2 contribute to the high pathogenicity of the H5N1 HPAI viruses in chickens, and valine at position 105 of NP may be one of the determinants for adaptation of avian influenza viruses from ducks to chickens.

A digital output piezoelectric accelerometer using a Pb(Zr, Ti)O3 thin film array electrically connected in series

A digital output piezoelectric accelerometer is proposed to realize an ultra-low power consumption wireless sensor node. The accelerometer has patterned piezoelectric thin films (piezoelectric plates) electrically connected in series accompanied by CMOS switches at the end of some of the piezoelectric plates. The connected piezoelectric plates amplify the output voltage without the use of amplifiers. The CMOS switches turn on when the output voltage of the piezoelectric plates is higher than the CMOS threshold voltage. The piezoelectric accelerometer converts the acceleration into a number of on-state CMOS switches, which can be called the digital output. The proposed digital output piezoelectric accelerometer, using Pb(Zr, Ti)O3 (PZT) thin films as the piezoelectric material, was fabricated through a microelectromechanical system (MEMS) microfabrication process. The output voltage was found to be amplified by the number of connected piezoelectric plates. The DC output voltage obtained by using an AC to DC conversion circuit is proportional to the number of connections. The results show the potential for realizing the proposed digital output piezoelectric accelerometer.

Wireless sensor system for detection of avian influenza outbreak farms at an early stage

We developed a prototype wearable wireless node with a thermister and an accelerometer for a chicken, and evaluated the availability of a method for detecting chickens infected with the highly pathogenic avian influenza (HPAI) viruses using data at the early stage. Chicken infection experiments by using the wireless node showed that weakness and fever of the infected chickens were detectable before chickens showed clinical signs and gross lesions, and death of infected chickens was noticed by the sudden decrease in body temperature. This study indicates a possibility that the wearable wireless node would be a useful tool for detecting the HPAI outbreaks at the farms, and sudden increase in fever, weakness and the death in a chicken house would be the early signal for the outbreaks.

Ultra-Low Power Event-Driven Wireless Sensor Node Using Piezoelectric Accelerometer for Health Monitoring

We describe a low power consumption wireless sensor node designed for monitoring the conditions of animals, especially of chickens. The node detects variations in 24-h behavior patterns by acquiring the number of the movement of an animal whose acceleration exceeds a threshold measured in per unit time. Wireless sensor nodes when operated intermittently are likely to miss necessary data during their sleep mode state and waste the power in the case of acquiring useless data. We design the node worked only when required acceleration is detected using a piezoelectric accelerometer and a comparator for wake-up source of micro controller unit.

A digital output piezoelectric accelerometer for ultra-low power wireless sensor node

We have developed a novel piezoelectric accelerometer with digital output for ultra-low power wireless sensor nodes. The accelerometer is composed of an array of piezoelectric parallel-plate capacitor structures that are joined together in series and connected to a CMOS switch array. This composition makes it possible to realize a digital output accelerometer in which the number of on-state CMOS switches increases with increasing acceleration. The switches can be turned on by the voltage generated due to the piezoelectric effect and then the acceleration can be directly converted to digital output without an A/D converter. In this study, we have designed this type of accelerometer and developed its fabrication process utilizing SOI wafer and solgel derived PbZrTiO3 (PZT) thin films. And a wireless sensor node integrated with the fabricated accelerometer device has been demonstrated. Evaluating the devices, it has been shown that an ultra-low power accelerometer can be realized with improving the piezoelectric property of the piezoelectric thin film.

Toward the World Smallest Wireless Sensor Nodes With Ultralow Power Consumption

Pursuit of the lowest size-limit of wireless sensor nodes may not only reduce power consumption and production cost, but also enables its layout-free ubiquitous applications, i.e., in our green sensor networks to compress energy consumption through visibility and optimization. In this paper, we engaged in developing the world smallest wireless sensor node with ultralow power consumption from both electrical block integration and physical interconnection points-of-view. A customized IC for signal processing and data transmission, which has universal interface to sensors and power management capability, was designed and then fabricated by using 0.18 μm 1.8 V/3.3 V 1P6M logic process. By introducing buried bump interconnection technology, we have successfully obtained one of the worlds smallest wireless sensor nodes, as small as 3.9 mm × 3.9 mm × 3.5 mm, for humidity and temperature monitoring. The sensor node also features an general purpose interface, available for analog and digital sensors, and the ultrasmall footprint of above sensor node enables its layout-free distribution or integration inside other remote sensing systems. Although the adopted antenna size was 2 cm × 5 cm, its flexibility enables free attach to any curved surfaces. Experimental results demonstrated that besides preferred ultralow power consumption and data transmission distance, configuration of above sensor nodes enables its easy assembly with stand-alone power source and flexible antenna for wide variety of applications.

Development of a Wireless Sensor for the Measurement of Chicken Blood Flow Using the Laser Doppler Blood Flow Meter Technique

Here, we report the development of an integrated laser Doppler blood flow micrometer for chickens. This sensor weighs only 18 g and is one of the smallest-sized blood flow meters, with no wired line, these are features necessary for attaching the sensor to the chicken. The structure of the sensor chip consists of two silicon cavities with a photo diode and a laser diode, which was achieved using the microelectromechanical systems technique, resulting in its small size and significantly low power consumption. In addition, we introduced an intermittent measuring arrangement in the measuring system to reduce power consumption and to enable the sensor to work longer. We were successfully able to measure chicken blood flow for five consecutive days, and discovered that chicken blood flow shows daily fluctuations.