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A survey of Potato virus Y (PVY) was conducted in farmers' fields in 9 Korean provinces, Gyeonggi-do, Gangwon-do, Gyeongsangnam-do, Gyeongsangbuk-do, Jeollanam-do, Jeollabuk~io, Chungchcongnam-do, Chungcheongbuk-do and Jeju-do from 1998 to 2000. One hundred and fifty nine samples from potato and tobacco were collected and analyzed. Based on ELISA results, three samples PVY-tob, PVY-potlii and PVY-pot-chw representing PVYN and PVYo, respectively, were further subjected to biological, serological and molecular analysis. Host range studies showed that PVY-pot-chw is symptomatically distinguishable from PVY-tob and PVY-pot-j isolates, both of which were symptomatically indistinguishable. However, all the three isolates failed to infect 10 capsicum varieties systemically. Isolates PVY-tob and PVY-pot-j reacted strongly wlth monoclonal antibody (MAb), anti-PVYN while PVY-pot-chw failed to react wlth the MAb but reacted strongly wlth anti-PVYo'c. Interestingly, both PVY-tob and PVY-pot-j isolates did not react with anti-Pvyo,C indicating that isolate PVY-pot-chw is serologically distinguishable from both PVY-tob and PVY-potlii. In order to ascertain the taxonomic status of the three isolates, the 3' untranslated terminal regions (3'-UTR) were sequenced. Alignment of the sequences revealed 990/0 sequence identity between PVY-tob and PVY-pot-j, both of which had 780/0 nt sequences identical to PVY-pot-chw. Phylogenetic analysis of the aligned 3'-UTRs clustered PVY-tob and PVY-pot-j in the PVY~ subgroup, and PVY-pot~:hw in the PVYO subgroup.

Patients with sensorineural hearing loss can recover their hearing using a cochlear implant (CI). However, there is a need to develop next-generation CIs to overcome the limitations of conventional CIs caused by extracorporeal devices. Recently, artificial basilar membranes (ABMs) are actively studied for next-generation CIs. The ABM is an acoustic transducer that mimics the mechanical frequency selectivity of the BM and acoustic-to-electrical energy conversion of hair cells. This paper presents recent progress in biomimetic ABMs. First, the characteristics of frequency selectivity of the ABMs by the trapezoidal membrane and beam array are addressed. Second, to reflect the latest research of energy conversion technologies, ABMs using various piezoelectric materials and triboelectric-based ABMs are discussed. Third, in vivo evaluations of the ABMs in animal models are discussed according to the target position for implantation. Finally, future perspectives of ABM studies for the development of practical hearing devices are discussed.

In this paper, we present a flexible artificial basilar membrane (FABM) that mimics the passive mechanical frequency selectivity of the basilar membrane. The FABM is composed of a cantilever array made of piezoelectric aluminum nitride (AlN) on an SU-8 substrate. We analyzed the orientations of the AlN crystals using scanning electron microscopy and x-ray diffraction. The AIN crystals are oriented in the c-axis (0 0 2) plane and effective piezoelectric coefficient was measured as 3.52 pm V−1. To characterize the frequency selectivity of the FABM, mechanical displacements were measured using a scanning laser Doppler vibrometer. When electrical and acoustic stimuli were applied, the measured resonance frequencies were in the ranges of 663.0–2369 Hz and 659.4–2375 Hz, respectively. These results demonstrate that the mechanical frequency selectivity of this piezoelectric FABM is close to the human communication frequency range (300–3000 Hz), which is a vital feature of potential auditory prostheses.

A piezoelectric micromachined ultrasonic transducer (pMUT) is an ideal device for portable medical diagnosis systems, intravascular ultrasound systems, and ultrasonic cameras because of its favorable characteristics including small size, acoustic impedance matching with the body, low power consumption, and simple integration with the systems. Despite these advantages, practical applications are limited because of insufficient acoustic pressure of the pMUT caused by the thin active piezoelectric layer. Here, we report the fabrication of a thick piezoelectric Pb(Zr,Ti)O3 (PZT) film-based pMUT device having high deflection at low driving voltage using the granule spraying in vacuum (GSV) process. Pre-patterned high-density thick (exceeding 8 μm) PZT films were grown on 6-inch-diameter Si/SiO2/Ti/Pt silicon-on-insulator wafers at room temperature at a high deposition rate of ∼5 μm min−1. The fabrication process using the proposed GSV process was simple and fast, and the deflection of the pMUT exhibited a high...

Electrodeposition is a versatile method, which enables the fabrication of a variety of wire-like nanoarchitectures such as nanowires, nanorods, and nanotubes. By means of template-assisted electrodeposition, segmented Au/Co/Au nanowires are grown in anodic aluminum oxide templates from two different electrolytes. To tailor the properties of the cobalt segments, several electrochemical conditions are studied as a function of current density, pulse deposition, and pH. The morphology, crystal structure, and magnetic properties are accordingly investigated. Changes in the deposition conditions affect the cobalt electrocrystallization process directly. Cobalt tends to crystallize mainly in the hexagonal close-packed structure, which is the reason cobalt might not accommodate satisfactorily on the face-centered cubic Au surface or vice versa. We demonstrate that by modifying the electrolyte and the applied current densities, changes in the texture and the crystalline structure of cobalt lead to a good quality connection between dissimilar segments. In particular, lowering the bath pH, or using pulse plating at a high overpotential, produces polycrystalline fcc Co and thus well-connected Co/Au bimetallic junctions with smooth interface. These are crucial factors to be carefully considered taking into account that nanowires are potential building blocks in micro- and nanoelectromechanical systems.

Energy distribution under the human skin during ultrasound power transfer using a 15×15 MEMS transducer array with 2.2 MHz driving frequency is presented in this paper. When the surface pressure of the array element is 96 kPa, intensity at 2 mm under the skin is 0.96 W/cm2; intensity increases to 24 W/cm2 when the surface pressure increases to 0.48 MPa. In other words, the simulation results show that the larger the surface pressure, the larger the intensity. The simulated and the measured power density values at 7 mm in the vertical direction of the transducer surface in degassed water are 96.72 mW/cm2 and 94.08 mW/cm2, respectively. Temperature change due to ultrasound radiation on the skin is discussed, and the feasibility of ultrasonic power transfer for implantable medical devices specially implanted just underneath the skin is presented.

Field disease incidences of squash virus diseases in Jeonnam province were estimated to be 76.1% and of delayed planting on August-September (retarding culture) and on February-March (semi-forcing culture) on glass house were 55.0% and 0%, respectively, in 2000. Disease incidences of individual squash plant within a field were 100% and 3.6%, respectively, in wild culture and retarding culture. Total of 61 samples suspected to be infected with viruses were collected in 2000 and tested by RT-PCR using specific oligonulceotide primer sets designed for the detection of Cucumber green mottle mosaic virus (CGMMV), Kyuri green mottle mosaic virus (KGMMV), Zucchini yellow mosaic virus (ZYMV), Papaya ring spot virus (PRSV), Watermelon mosaic virus (WMV), and Cucumber mosaic virus (CMV). Each specific primer set for WMV, ZYMV, and PRSV amplified expected size of DNA fragments from 16, 10, and 2 samples in wild culture, respectively. Double or triple infection were observed in 7 samples tested. In contrast, each specific primer set for WMV, ZYMV, and PRSV confirmed virus infection from 7, 6, and 6 samples, respectively, in samples collected from semi-forcing culture. Double infection of WMV and PRSV was observed in only one sample. However, no DNA fragment was amplified from RT-PCR using CGMMV, KGMMV, and CMV specific oligonucleotide primer sets indicating no CGMMV, KGMMV, or CMV infection in squash fields in Jeonnam province in 2000.

Here, we present a method for fabrication of full three-dimensional porous microstructures (microscaffolds) using photocurable polymer. The structures were coated with nickel and titanium for magnetic manipulation and biocompatibility, respectively. Fabricated microstructures were controlled by external magnetic fields for remote actuation. Human embryonic kidney 293 cells were cultured in the microstructures to demonstrate their feasibility for cell transportation. The fabricated microstructures described here are suitable for targeted cell transportation platforms.

Accurate control is necessary to enhance the practical usage of microrobots during in-vivo applications to achieve their goal. Electromagnetic in-vivo manipulation of microrobots in a low Reynolds number flow imposes uncertainties and nonlinearities which cannot be completely known and modeled to the robot dynamics. This paper presents a controller based on time delay estimation (TDE) of uncertainties. The controller does not use any information of the system and estimates the unknown terms. Our Simulation shows that the TDE controller is robust for magnetic steering of microrobots. Experiments demonstrate the successful simulation results and the ability of the simply implementable control scheme by step inputs and complex paths.

We developed a simple method for real-time detection of the neurite outgrowth using microfluidic device. Our microfluidic device contains three compartmentalized channels which are for cell seeding, hydrogel and growth factors. Collagen gel is filled in the middle channel and pheochromocytoma (PC12) cells are seeded in the left channel. To induce differentiation of PC12 cells, 50 ng/ml to1000 ng/ml of nerve growth factor (NGF) is introduced into the right channel. After three days of NGF treatment, PC12 cells begin to extend neurites and formed neurite network from sixth day. Quantification of neurite outgrowth is analyzed by measuring the total area of neurites. On sixth day, the area is doubled compared to the area on third day and increases by 20 times on ninth day.

Hyper-networked Li(4)Ti(5)O(12)/carbon hybrid nanofiber sheets that contain both a faradaically rechargeable battery-type component, namely Li(4)Ti(5)O(12), and a non-faradaically rechargeable supercapacitor-type component, namely N-enriched carbon, are prepared by electrospinning and their dual function as a negative electrode of lithium-ion batteries (LIBs) and a capacitor is tested for a new class of hybrid energy storage (denoted BatCap). An aqueous solution composed of polyvinylpyrrolidone, lithium hydroxide, titanium(IV) bis(ammonium-lactato)dihydroxide and ammonium persulfate is electrospun to obtain hyper-networked nanofiber sheets. Next, the sheets are exposed to pyrrole monomer vapor to prepare the polypyrrole-coated nanofiber sheets (PPy-HNS). The hyper-networked Li(4)Ti(5)O(12)/N-enriched carbon hybrid nanofiber sheets (LTO/C-HNS) are then obtained by a stepwise heat treatment of the PPy-HNS. The LTO/C-HNS deliver a specific capacity of 135 mAh g(-1) at 4000 mA g(-1) as a negative electrode for LIBs. In addition, potentiodynamic experiments are performed using a full cell with activated carbon (AC) as the positive electrode and LTO/C-HNS as the negative electrode to estimate the capacitance properties. This new asymmetric electrode system exhibits a high energy density of 91 W kg(-1) and 22 W kg(-1) at power densities of 50 W kg(-1) and 4000 W kg(-1), respectively, which are superior to the values observed for the AC [symbol: see text] AC symmetric electrode system.

A novel soybean-infecting sobemovirus termed Soybean yellow common mosaic virus (SYCMV) was characterized. The virus has a single, positive-strand RNA genome of 4152 nucleotides. The virus contains four putative open reading frames encoding P1 (78-566 nt), polyprotein ORF2a (524-2248 nt), polymerase domain ORF2b (1852-3417 nt), and CP (3227-4030 nt). The entire nucleotide sequence of SYCMV showed 31.2-71.3% nucleotide identity with the previously known eleven species of sobemovirus. In host range analysis of SYCMV, in which twenty one species and three different Nicotiana tabacum cultivars belonging to seven families were inoculated with the virus, SYCMV had a narrow host range, infecting only Glycine max and G. soja. Based on the obtained sequence, full-length clones of SYCMV were constructed. Symptoms produced by inoculation with clones were indistinguishable from those produced by inoculation with sap from symptomatic plants. Viral RNA accumulation of SYCMV was detected in the upper leaves by Northern blotting. This indicated that full-length clones of SYCMV were sufficient to produce disease symptoms. Genomic organization, the predicted amino acid sequence, and phylogenetic analyses with known sobemoviruses confirmed the assignment of SYCMV as a new member of the genus Sobemovirus.

Zinc Oxide nanostructures are capable of applying numerous applications such as optoelectronics, sensors, varistors, and electronic devices. There are several techniques to gorw ZnO nanostructures, including vapor-liquid-solid method, chemical vapor deposition, physical vapor deposition, metal organic chemical vapor deposition and solution process. Recently reported solution method is a simple way to grow ZnO nanowires at a low temperature. One distinctive advantage with the solution method is low processing temperature so that flexible polymer materials can be used as a substrate to grow ZnO nanowires. In this study, ZnO nanowires have been fabricated on PET film by solution method with various molarities to see the effect of different molarities on ZnO nanowire growth. The solution temperature was 80°C and ZnO nanowires were grown for 6 hours for each case. The ZnO seed layer was sputtered at room temperature for 33 min. prior to ZnO nanowire growth. These ZnO nanowires were characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and photoluminescence (PL) measurements at room temperature using a He-Cd 325-nm laser as the excitation source. We also measured the current using current Atomic Force Microscopy (I-AFM) and presented the possibility to use ZnO nanowires as a power source for micro/nano scale devices. As a result, we found that the characterization of ZnO nanowires changes according to the solution molarity.

ZnO nanowires can convert mechanical energy into electrical energy and we investigated energy conversion of ZnO nanowires grown on a silicon substrate. First, we numerically studied the output voltages of ZnO nanowires while varying diameters and lengths of ZnO nanowires. Second, we measured the currents of ZnO nanowires grown at low temperature using a solution method. The currents were measured using a Current Atomic Force Microscope (I-AFM). ZnO nanowires produced output current pulses when scanned by I-AFM in contact mode because of the piezoelectric effect of ZnO nanowires when the I-AFM tip applied a lateral force to ZnO nanowires.

Thin film structures have found a wide variety of applications in electromechanical technologies. As the design flexibility for these structures increases, so does the demand for design software that can provide some good insights into the behavior of the structure before it is fabricated. In this study, a finite element code based on a combination of equivalent single-plate theory and classical laminated plate theory was used to predict the dynamic response of thin film structures in micro length scale. As a benchmark for the code development, thin film structures were also fabricated using MEMS technology, and their fundamental frequencies were characterized. It was demonstrated that the model predictions matched fairly well with the experimental data for the small membranes with widths less than 200 microm, but underestimated them for large ones with widths greater than 500 microm. The model also demonstrated that the fundamental frequencies increased with the thickness of the layers. The areas that need to be investigated further in order to improve the predicative capability of the calculations include effects of residual stress, dc bias voltage, parasitic capacitance, interaction of membrane vibration with the supports of the structure, and accurate measurement of the dimensions and material properties of the thin films.

We design and fabricate segmented annular arrays (SAAs) using piezoelectric micromachined ultrasonic transducers (pMUTs) to demonstrate the feasibility of acoustic focusing of ultrasound. The fabricated SAAs have 25 concentric top-electrode signal lines and eight bottom-electrodes for grounding to enable electronic steering of selectively grouped ultrasonic transducers from 2393 pMUT elements. Each element in the array is connected by top-crossover-to-bottom metal bridges, which reduce the parasitic capacitance. Circular-shaped pMUT elements, 120 μm in diameter, are fabricated using 1 μm-thick sol–gel lead zirconate titanate on a silicon wafer. To utilize the high-density pMUT array, a deep reactive ion etching process is used for anisotropic silicon etching to realize the transducer membranes. The resonant frequency and effective coupling coefficient of the elements, measured with an impedance analyzer, yields 1.517 MHz and 1.29%, respectively, in air. The SAAs using pMUTs are packaged on a printed circuit board and coated with parylene C for acoustic intensity measurements in water. The ultrasound generated by each segmented array is focused on a selected point in space. When a 5 Vpp, 1.5 MHz square wave is applied, the maximum spatial peak temporal average intensity () is found to be 79 mW cm−2 5 mm from the SAAs' surface without beamforming. The beam widths (−3 dB) of ultrasonic radiation patterns in the elevation and azimuth directions are recorded as 3 and 3.4 mm, respectively. The results successfully show the feasibility of focusing ultrasound on a small area with SAAs using pMUTs.

The objective of the current study is to investigate the size effect on the performance of piezoelectric micromachined ultrasonic transducers (pMUTs). pMUTs with twenty different dimensions were designed and fabricated. The length/width aspect ratios of the membranes range from 5 to 22. For each design, multiple samples were fabricated in order to collect statistically meaningful data. The performance of pMUTs was characterized by the impedance and phase angle measurements combined with equivalent circuit analysis. The circuit has four electrical components, L1 (motional inductance), C1 (motional capacitance), R1 (motional resistance), and C0 (parallel capacitance), and their values were determined by fitting the circuit equation to the experimental data. The experimental results showed that effective coupling coefficient ( keff 2) increase, and resonance frequency ( fs) and quality factor (Q ) decrease with increasing the width of the membrane.

In this study, a finite element code based on a combination of equivalent single-plate theory and classical laminated plate theory was used to study the dynamic behavior of the thin film membrane structures. The structure studied was piezoelectric micromachined ultrasonic transducer (pMUT) fabricated with MEMS technology. The membrane has two different shapes, square and rectangular. Two different types of boundary conditions were considered for modeling, namely, simply supported vs. clamped. It is demonstrated that the model generates correct qualitative trend for the mechanical responses of pMUT structure. Quantitatively, for relatively larger (greater than 1 mm) thin membrane structures, the measured fundamental frequencies fall between the predictions based on clamped and simply supported boundary conditions. However, for smaller structures, both predictions overestimate them. The possible reasons for this discrepancy include the interaction of membrane vibration with the supports of the structure, residual stress, DC bias voltage, parasitic capacitance, and uncertainty of the dimensions and material properties of the constituent thin films

The assessment of musculoskeletal disorders prevalent among industrial workers involved in manual tasks is a difficult and time-consuming process. This paper presents the integration of the rapid upper limb assessment (RULA) algorithm, a well-established ergonomic tool, with a virtual assembly tool (VADE), to facilitate the identification of potential upper limb injuries in assembly processes and identification of potential solutions. In this context, a parametric human model was embedded into the virtual assembly system. The posture of the worker is analyzed continuously (at each frame) in real-time, as he/she performs the task. This allows the engineer to try out different postures and assembly processes quickly to identify the best work environment set-up. One pilot study is presented in this paper to demonstrate the application of this concept. This pilot study (conducted jointly with an industry partner) clearly illustrates the validity and utility of this method in identifying and reducing manual assembly process related musculoskeletal stresses.Copyright © 2003 by ASME

Accurate control systems are critical for safe and practical utilization of microrobots for in vivo operations. There exist uncertainties from the microrobot dynamics and nonlinearities from the magnetic driving force in the electromagnetic in vivo manipulation of microrobots, especially in low Reynolds number fluid flow. We describe the modeling and implementation of a closed-loop control system for a magnetically actuated microrobot based on time-delay estimation (TDE). The microrobot consisted of a cylindrical magnet, 0.5 mm in diameter and 1 mm in length, and the controller used optical sensing for position feedback. In addition, we describe an analytical model to determine the magnetic field components and the field gradients of a custom set of coils used to actuate the microrobot. Simulations were carried out to investigate the properties of the TDE control system, and it was subsequently tested experimentally, demonstrating that it provides robust control of the microrobot trajectory and does not exhibit chattering to follow step inputs.

A strategy for fabricating organic photovoltaic (OPV) devices based on PCDTBT nanofibers and PC70BM is described. Electrospinning techniques are used to prepare PCDTBT nanofibers and OPV devices in ambient air. The diameters of the PCDTBT nanofibers are approximately twice the exciton diffusion length, 20 nm. The active layer exhibits 100% photoluminescence quenching due to the small nanofiber diameter, indicating that the excitons are efficiently dissociated. The electrospun PCDTBT nanofibers absorb more photons at longer wavelengths, leading to improved photon harvesting. OPV devices composed of PCDTBT nanofibers show a high short circuit current of 11.54 mA cm(-2) and a high power conversion efficiency of 5.82%. The increase in the short circuit current is attributed to enhanced photon harvesting and charge transport. This method may be applied to the fabrication, in ambient air, of large-area active layers composed of other new conjugated polymers to yield high-performance OPV devices.

A new design methodology and fabrication process for two-dimensional (2D) piezoelectric micromachined ultrasonic transducer (pMUT) arrays using a top-crossover-to-bottom (TCTB) structure was developed. Individual sensing and actuation of pMUT elements from a small number of connection lines was enabled by the TCTB structure, and the parasitic coupling capacitance of the array was significantly reduced as a result. A 32 × 32 pMUT array with a TCTB structure was fabricated, resulting in 64 connection lines over an area of 4.8 × 4.8 mm2. The top electrodes for each pMUT element were re-connected by metal bridging after bottom-electrode etching caused them to become disconnected. A deep reactive ion etching process was used to compactify the array. Each pMUT element was a circular-shaped K31-type ultrasonic transducer using a 1 µm thick sol–gel lead zirconate titanate (PZT: Pb1.10 Zr0.52 Ti0.48) thin film. To characterize a single element in the 2D pMUT array, the resonant frequency and coupling coefficient of 20 pMUT elements were averaged to 3.85 MHz and 0.0112, respectively. The maximum measured ultrasound intensity in water, measured at a distance of 4 mm, was 4.6 µW cm−2 from a single pMUT element driven by a 5 Vpp sine wave at 2.22 MHz. Potential applications for development of a TCTB-arranged 2D pMUT array include ultrasonic medical imaging, ultrasonic communication, ultrasonic range-finding and handwriting input systems.

The study presented in this paper assessed the frequency selectivity of an artificial basilar membrane (ABM) constructed using a piezoelectric beam array with narrow supports. Three ABM samples were constructed. Each ABM contained 16 beams with various lengths in a one-dimensional array. To experimentally assess the frequency selectivity of the ABM, mechanical vibration induced either by an electrical or an acoustic stimulus was measured with a scanning laser-Doppler vibrometer. The electro-mechanical and acousto-mechanical transfer functions were defined for the same purpose. The tonotopy of each beam array was visualized by post-processing the experimental results. Finite element analyses were conducted to numerically compute the resonance frequencies, identify the associated vibrational modes, and evaluate the harmonic responses of the beams. The influence of the residual stresses existing in the beams was reflected in the geometric models by introducing three different levels of arc-shaped lateral deformations in the beams. The harmonic analyses revealed that each beam of the ABM samples presented independent band-pass characteristics. The experiments and simulations commonly showed a frequency selectivity of the fabricated ABMs in the range of 2?20?kHz. Therefore, the device is suitable for development of a totally implantable artificial cochlea, implementing a mechanical frequency analyzer. This work is part of research to develop a prototype of a totally implantable artificial cochlea.

Peanut stunt virus (PSV) is a member of the genus Cucumovirus inthe family Bromoviridae. Other members of the genus are its typemember Cucumber mosaic virus (CMV) and Tomato aspermy virus(TAV). PSV like other cucumoviruses has a tripartite genome ofpositive strand RNAs, designated RNA1, RNA2 and RNA3, inother decreasing size. PSV is an economically important pathogenand occurs worldwide in legume plants. Since PSV was firstdescribed in the United States in 1966, many strains of PSV havebeen characterized. In Korea, there has been previous record on PSVinfection of peanut, black locast, red goosefoot and white clover(The Korean Society of Plant Pathology 2009)., In Sangju County ofSouth Korea in 2005, a PSV (PSV-K1) was first detected using RT-PCR from naturally infected soybean showing yellow mosaic on theleaves and virus particles were isolated from these infected leaves(Fig. 1A). Purified virus preparations were revealed the presence ofsmall isometric virions of 28 nm in diameter (Fig. 1B).The nucleotide sequence of full-length RNA3 from PSV strainK1 was determined. PSV-K1 RNA3 is 2089 nucleotides (nt)organized into two putative ORFs and 5'- and 3'-untranslatedregions (UTRs) of 52 and 229nt, respectively. Two large openreading frames (ORFs) encoded a putative movement protein (MP)(nt 53 −925) and a coat protein (CP) (nt 1183 −1860) predicted to be a31-kDa protein (P31) and a 25-kDa protein (P25), respectively.ORF3a (MP) is separated from the next ORF3b (CP) by an IR non-coding region (internal region) 257nt in length (nt 926 −1182).Multiple sequence alignments were generated using DNAMAN7.0 (Lynnon Biosoft, Quebec, Canada) on the basis of completenucleotide sequences of PSV RNA3, and a phylogenetic tree wasconstructed by the neighbor-joining algorithm (Fig. 2). Bootstrapanalysis was performed with 1,000 replicates. The resulting tree ofRNA3 revealed that PSV-K1 RNA3 is more closely related to that ofPSV-ER (94.6%) than to those of other cucumoviruses. Percentnucleotide sequence identities of RNA3 from PSV-K1 ranged from58.7 to 94.6% with RNA3 sequences of members of the genusCucumovirus. PSV was first divided into two subgroups based on awide range of comparative analyses, including serology, competi-tion hybridization and sequence comparison (Hu et al., 1997).Recently, the complete nucleotide (nt) sequence of PSV-Mi andPSV-Rp strain was determined, and based on nt sequence diversity,the establishment of a subgroup and was proposed (Yan et al., 2005and Kiss et al., 2008).Phylogenetic analyses of PSV-K1 show clearly that this strain isrelated to representatives of subgroup containing PSV-ER B. ased onthese data, we conclude that PSV is closely related to PSV-ER strainfrom cowpea and it is the first report of PSV on soybean in Korea.

A low phase noise voltage controlled oscillator (VCO) is proposed by employing two positive feedback loops. One of them is used to enhance the output signal swing of the VCO while the other cancels the noise of active devices to reduce the noise contribution of those devices to the phase noise of the VCO. The proposed VCO is fabricated in a 0.18 μm 1P6M CMOS process. The measurement result shows that the phase noise is 126.6 dBc/Hz at 1 MHz offset frequency from the oscillation frequency of 3.8 GHz while dissipating 5.1 mA from a 1.0 V supply voltage with a FOM of 191.1 dBc/Hz.

The battery–supercapacitor hybrid electrode, consisting of both faradaic rechargeable battery components and non-faradaic rechargeable supercapacitor components in a single electrode, is successfully developed using Li4Ti5O12–activated carbon (LTO–AC) hybrid nanotubes in a negative electrode for an advanced energy storage device. Li4Ti5O12 and PVA-derived activated carbon are hybridized with morphological control over the one-dimensional (1D) tubular structures via an in situ sol–gel reaction combined with electrospinning, followed by a hydrothermal reaction and appropriate heat treatment. The prepared LTO–AC hybrid nanotubes are tested at a variety of charge–discharge rates as anode materials for use in lithium-ion rechargeable batteries that deliver a specific capacity in the range of 128–84 mA h g−1 over a 100–4000 mA g−1 charge–discharge rate in the potential range 1.0–2.5 V vs. Li/Li+. The hybridized LTO–AC hybrid nanotubes electrode is included in a new type of hybrid energy storage cell, denoted as BatCap, as the negative electrode using commercialized activated carbon (AC) as the positive electrode. The hybrid BatCap cell exhibits a high energy density of 32 W h kg−1 and a high power density of 6000 W kg−1, comparable to the properties of a typical AC symmetric capacitor.

One-dimensional conjugated polymers can be used to build unperturbed percolation pathways that transport electric charges in the active layer of an organic photovoltaic (OPV) cell. Electrospinning is known to be a facile method for the preparation of 1-D nanofibers, but the diameters of electrospun conjugated polymers have previously been too large for OPV cells. In particular, it has not been possible to electrospin poly(3-hexylthiophene) (P3HT) to produce homogeneous nanofibers. We report a new method for the preparation of homogeneous P3HT nanofibers with diameters less than 100 nm and examine the photoluminescence (PL) properties of these nanofibers as a preliminary test of their use in an OPV cell. Nanofibers of P3HT with diameters less than 100 nm can be successfully and simply electrospun by using the proposed method, in particular without adopting a dual nozzle system, with the aid of an auxiliary polymer, polyethylene oxide (PEO), and a polar solvent mixture consisting of chloroform, dimethylformamide (DMF), and acetic acid. After removal of the auxiliary polymer, a composite film composed of virgin P3HT nanofibers and PCBM was found to exhibit almost 100% PL quenching. These results suggest that the proposed method can be used to produce P3HT nanofibers with an efficient photo-energy conversion structure that is useful in OPV cells.

not Available.

A two-dimensional composite plate model was developed as part of the design methodology for micro-scale thin membrane structures in general and pMUTs in particular. The model was compared with a one-dimensional beam model developed earlier and experimental measurements. The two-dimensional model was shown to converge to the one-dimensional model for the structures with a large aspect ratio. Compared to the experimental data, the qualitative trends regarding the dependence of transducer performance on the aspect ratio predicted by the model were validated by the experimental measurements in all cases except that of the electromechanical coupling factor k2eff. The quantitative agreement between model and experimental data was quite good for all parameters at a transducer width of 180 µm, and became worse as the transducer width became smaller. The resonance frequency was predicted very well by the model, and did not depend on the aspect ratio. With the enhanced flexibility provided by the two-dimensional model, some optimization study was also performed. It was found that among different geometries, a square membrane, i.e. a membrane with the aspect ratio equal to 1, appears to have the highest effective coupling coefficient. On the other hand, for a given square membrane, the electrode which covers about 25% of the membrane, i.e. 50% of the width and length measured from the center, possesses the optimized coupling coefficient. In practice, the model can be used to first optimize the dimension of the membrane for pMUTs to obtain the targeted frequencies and then the electrode coverage area for optimized coupling coefficient.

The objective of the current study was to characterize and model the performance of piezoelectric micromachined ultrasonic transducers (pMUTs) with large length/width aspect ratios. Single-element pMUTs with 20 different dimensions corresponding to aspect ratios ranging from 5:1 to 23:1 were designed. Multiple samples were fabricated for each design so that statistically meaningful data could be obtained. The pMUTs were characterized by the impedance measurement combined with an equivalent circuit analysis. A one-dimensional composite beam model was also used to correlate the equivalent circuit components with the structural parameters, and gain insight into the performance characteristics of pMUTs. The resonant frequencies were observed to decrease with the width of the membrane, but have no appreciable length dependence. With the correction of parasitic capacitance, the effective coupling coefficients were observed to increase with the width up to around 150 µm and then decrease. However, they did not show clear and consistent length dependence. The variation of the coupling coefficient as a function of width of the membrane was shown to be mainly due to the relative ratios between the electrode and membrane widths rather than membrane width itself. Although the model presented in this study was a simple one-dimensional electro-mechanical model, it did seem to offer both good qualitative and quantitative insights into the performance of pMUTs and provide a convenient tool for designing thin membrane transducers with a large aspect ratio. The model can also take into consideration the residual stress effect and offer an even more realistic prediction.

Cell therapy refers to a treatment that involves the delivery of cells or cellular material by means of injection, grafting, or implantation in order to replace damaged tissue and restore its function, or to aid the body in fighting disease. However, limitations include poor targeting delivery and low therapeutic efficacy due to low cell survival. Hence, novel approaches are required to increase cell delivery efficiency and enhance therapeutic efficacy via selective cell differentiation at target areas. Here, we present a stamping magnetoelectric microscale biorobot (SMMB) consisting of neuron-like cell spheroids loaded with magnetoelectric nanoparticles. The SMMB enables not only effective targeted delivery of cells to multiple target areas (via minimally invasive stamping employing magnetic actuation) but also facilitates selective neuronal differentiation via magnetoelectric (ME) stimulation. This ensures rapid colonization and enhances efficacy. SMMBs were fabricated using SH-SY5Y cells. Magnetoelectric nanoparticles for ME stimulation responded to an alternating magnetic field that ensured targeted cell differentiation. Multi-target cell therapy facilitated the targeted delivery and selective differentiation of SH-SY5Y cells to multiple regions using a single SMMB with rotating and alternating magnetic fields for delivery and ME stimulation. This promising tool may overcome the limitations of existing cell therapy for neurodegenerative diseases., Materials Horizons, 9 (12), ISSN:2051-6347, ISSN:2051-6355