Effects of single pulse energy on the properties of ceramic coating prepared by micro-arc oxidation on Ti alloy

NASA Astrophysics Data System (ADS)

Wang, Jun-Hua; Wang, Jin; Lu, Yan; Du, Mao-Hua; Han, Fu-Zhu

2015-01-01

The effects of single pulse energy on the properties of ceramic coating fabricated on a Ti-6Al-4V alloy via micro-arc oxidation (MAO) in aqueous solutions containing aluminate, phosphate, and some additives are investigated. The thickness, micro-hardness, surface and cross-sectional morphology, surface roughness, and compositions of the ceramic coating are studied using eddy current thickness meter, micro-hardness tester, JB-4C Precision Surface roughness meter, scanning electron microscopy (SEM) and X-ray diffraction (XRD). Single pulse energy remarkably influences the ceramic coating properties. The accumulative time of impulse width is an important parameter in the scientific and rational measurement of the film forming law of ceramic coating. The ceramic coating thickness approximately linearly increases with the cumulative time of impulse width. Larger impulse width resulted in higher single pulse energy, film forming rates and thicker ceramic coating thickness. The sizes of oxide particles, micro-pores and micro-cracks slightly increase with impulse width and single pulse energy. The main surface conversion products generated during MAO process in aqueous solutions containing aluminate are rutile TiO2, anatase TiO2, and a large amount of Al2TiO5. The effects of single pulse energy on the micro-hardness and phase composition of ceramic coating are not as evident as those of frequency and duty cycle.

Design of a self-calibration high precision micro-angle deformation optical monitoring scheme

NASA Astrophysics Data System (ADS)

Gu, Yingying; Wang, Li; Guo, Shaogang; Wu, Yun; Liu, Da

2018-03-01

In order to meet the requirement of high precision and micro-angle measurement on orbit, a self-calibrated optical non-contact real-time monitoring device is designed. Within three meters, the micro-angle variable of target relative to measuring basis can be measured in real-time. The range of angle measurement is +/-50'', the angle measurement accuracy is less than 2''. The equipment can realize high precision real-time monitoring the micro-angle deformation, which caused by high strength vibration and shock of rock launching, sun radiation and heat conduction on orbit and so on.

Study of nanometer-level precise phase-shift system used in electronic speckle shearography and phase-shift pattern interferometry

NASA Astrophysics Data System (ADS)

Jing, Chao; Liu, Zhongling; Zhou, Ge; Zhang, Yimo

2011-11-01

The nanometer-level precise phase-shift system is designed to realize the phase-shift interferometry in electronic speckle shearography pattern interferometry. The PZT is used as driving component of phase-shift system and translation component of flexure hinge is developed to realize micro displacement of non-friction and non-clearance. Closed-loop control system is designed for high-precision micro displacement, in which embedded digital control system is developed for completing control algorithm and capacitive sensor is used as feedback part for measuring micro displacement in real time. Dynamic model and control model of the nanometer-level precise phase-shift system is analyzed, and high-precision micro displacement is realized with digital PID control algorithm on this basis. It is proved with experiments that the location precision of the precise phase-shift system to step signal of displacement is less than 2nm and the location precision to continuous signal of displacement is less than 5nm, which is satisfied with the request of the electronic speckle shearography and phase-shift pattern interferometry. The stripe images of four-step phase-shift interferometry and the final phase distributed image correlated with distortion of objects are listed in this paper to prove the validity of nanometer-level precise phase-shift system.

A mechanically driven form of Kirigami as a route to 3D mesostructures in micro/nanomembranes.

PubMed

Zhang, Yihui; Yan, Zheng; Nan, Kewang; Xiao, Dongqing; Liu, Yuhao; Luan, Haiwen; Fu, Haoran; Wang, Xizhu; Yang, Qinglin; Wang, Jiechen; Ren, Wen; Si, Hongzhi; Liu, Fei; Yang, Lihen; Li, Hejun; Wang, Juntong; Guo, Xuelin; Luo, Hongying; Wang, Liang; Huang, Yonggang; Rogers, John A

2015-09-22

Assembly of 3D micro/nanostructures in advanced functional materials has important implications across broad areas of technology. Existing approaches are compatible, however, only with narrow classes of materials and/or 3D geometries. This paper introduces ideas for a form of Kirigami that allows precise, mechanically driven assembly of 3D mesostructures of diverse materials from 2D micro/nanomembranes with strategically designed geometries and patterns of cuts. Theoretical and experimental studies demonstrate applicability of the methods across length scales from macro to nano, in materials ranging from monocrystalline silicon to plastic, with levels of topographical complexity that significantly exceed those that can be achieved using other approaches. A broad set of examples includes 3D silicon mesostructures and hybrid nanomembrane-nanoribbon systems, including heterogeneous combinations with polymers and metals, with critical dimensions that range from 100 nm to 30 mm. A 3D mechanically tunable optical transmission window provides an application example of this Kirigami process, enabled by theoretically guided design.

A mechanically driven form of Kirigami as a route to 3D mesostructures in micro/nanomembranes

PubMed Central

Zhang, Yihui; Yan, Zheng; Nan, Kewang; Xiao, Dongqing; Liu, Yuhao; Luan, Haiwen; Fu, Haoran; Wang, Xizhu; Yang, Qinglin; Wang, Jiechen; Ren, Wen; Si, Hongzhi; Liu, Fei; Yang, Lihen; Li, Hejun; Wang, Juntong; Guo, Xuelin; Luo, Hongying; Wang, Liang; Huang, Yonggang; Rogers, John A.

2015-01-01

Assembly of 3D micro/nanostructures in advanced functional materials has important implications across broad areas of technology. Existing approaches are compatible, however, only with narrow classes of materials and/or 3D geometries. This paper introduces ideas for a form of Kirigami that allows precise, mechanically driven assembly of 3D mesostructures of diverse materials from 2D micro/nanomembranes with strategically designed geometries and patterns of cuts. Theoretical and experimental studies demonstrate applicability of the methods across length scales from macro to nano, in materials ranging from monocrystalline silicon to plastic, with levels of topographical complexity that significantly exceed those that can be achieved using other approaches. A broad set of examples includes 3D silicon mesostructures and hybrid nanomembrane–nanoribbon systems, including heterogeneous combinations with polymers and metals, with critical dimensions that range from 100 nm to 30 mm. A 3D mechanically tunable optical transmission window provides an application example of this Kirigami process, enabled by theoretically guided design. PMID:26372959

Slopes To Prevent Trapping of Bubbles in Microfluidic Channels

NASA Technical Reports Server (NTRS)

Greer, Harold E.; Lee, Michael C.; Smith, J. Anthony; Willis, Peter A.

2010-01-01

The idea of designing a microfluidic channel to slope upward along the direction of flow of the liquid in the channel has been conceived to help prevent trapping of gas bubbles in the channel. In the original application that gave rise to this idea, the microfluidic channels are parts of micro-capillary electrophoresis (microCE) devices undergoing development for use on Mars in detecting compounds indicative of life. It is necessary to prevent trapping of gas bubbles in these devices because uninterrupted liquid pathways are essential for sustaining the electrical conduction and flows that are essential for CE. The idea is also applicable to microfluidic devices that may be developed for similar terrestrial microCE biotechnological applications or other terrestrial applications in which trapping of bubbles in microfluidic channels cannot be tolerated. A typical microCE device in the original application includes, among other things, multiple layers of borosilicate float glass wafers. Microfluidic channels are formed in the wafers, typically by use of wet chemical etching. The figure presents a simplified cross section of part of such a device in which the CE channel is formed in the lowermost wafer (denoted the channel wafer) and, according to the present innovation, slopes upward into a via hole in another wafer (denoted the manifold wafer) lying immediately above the channel wafer. Another feature of the present innovation is that the via hole in the manifold wafer is made to taper to a wider opening at the top to further reduce the tendency to trap bubbles. At the time of reporting the information for this article, an effort to identify an optimum technique for forming the slope and the taper was in progress. Of the techniques considered thus far, the one considered to be most promising is precision milling by use of femtosecond laser pulses. Other similar techniques that may work equally well are precision milling using a focused ion beam, or a small diamond-tipped drill bit.

Method for forming precision clockplate with pivot pins

DOEpatents

Wild, Ronald L [Albuquerque, NM

2010-06-01

Methods are disclosed for producing a precision clockplate with rotational bearing surfaces (e.g. pivot pins). The methods comprise providing an electrically conductive blank, conventionally machining oversize features comprising bearing surfaces into the blank, optionally machining of a relief on non-bearing surfaces, providing wire accesses adjacent to bearing surfaces, threading the wire of an electrical discharge machine through the accesses and finishing the bearing surfaces by wire electrical discharge machining. The methods have been shown to produce bearing surfaces of comparable dimension and tolerances as those produced by micro-machining methods such as LIGA, at reduced cost and complexity.

Scale effects and a method for similarity evaluation in micro electrical discharge machining

NASA Astrophysics Data System (ADS)

Liu, Qingyu; Zhang, Qinhe; Wang, Kan; Zhu, Guang; Fu, Xiuzhuo; Zhang, Jianhua

2016-08-01

Electrical discharge machining(EDM) is a promising non-traditional micro machining technology that offers a vast array of applications in the manufacturing industry. However, scale effects occur when machining at the micro-scale, which can make it difficult to predict and optimize the machining performances of micro EDM. A new concept of "scale effects" in micro EDM is proposed, the scale effects can reveal the difference in machining performances between micro EDM and conventional macro EDM. Similarity theory is presented to evaluate the scale effects in micro EDM. Single factor experiments are conducted and the experimental results are analyzed by discussing the similarity difference and similarity precision. The results show that the output results of scale effects in micro EDM do not change linearly with discharge parameters. The values of similarity precision of machining time significantly increase when scaling-down the capacitance or open-circuit voltage. It is indicated that the lower the scale of the discharge parameter, the greater the deviation of non-geometrical similarity degree over geometrical similarity degree, which means that the micro EDM system with lower discharge energy experiences more scale effects. The largest similarity difference is 5.34 while the largest similarity precision can be as high as 114.03. It is suggested that the similarity precision is more effective in reflecting the scale effects and their fluctuation than similarity difference. Consequently, similarity theory is suitable for evaluating the scale effects in micro EDM. This proposed research offers engineering values for optimizing the machining parameters and improving the machining performances of micro EDM.

Fabrication of 3D electro-thermal micro actuators in silica glass by femtosecond laser wet etch and microsolidics

NASA Astrophysics Data System (ADS)

Li, Qichao; Shan, Chao; Yang, Qing; Chen, Feng; Bian, Hao; Hou, Xun

2017-02-01

This paper demonstrates a novel electro-thermal micro actuator's design, fabrication and device tests which combine microfluidic technology and microsolidics process. A three-dimensional solenoid microchannel with high aspect ratio is fabricated inside the silica glass by an improved femtosecond laser wet etch (FLWE) technology, and the diameter of the spiral coil is only 200 μm. Molten alloy (Bi/In/Sn/Pb) with high melting point is injected into the three-dimensional solenoid microchannel inside the silica glass , then it solidifys and forms an electro-thermal micro actuator. The device is capable of achieving precise temperature control and quick response, and can also be easily integrated into MEMS, sensors and `lab on a chip' (LOC) platform inside the fused silica substrate.

Exploiting microRNA Specificity and Selectivity: Paving a Sustainable Path Towards Precision Medicine.

PubMed

Santulli, Gaetano

2015-01-01

In his State of the Union address before both chambers of the US Congress, President Barack Obama called for increased investment in US infrastructure and research and announced the launch of a new Precision Medicine Initiative, aiming to accelerate biomedical discovery. Due to their well-established selectivity and specificity, microRNAs can represent a useful tool, both in diagnosis and therapy, in forging the path towards the achievement of precision medicine. This introductory chapter represents a guide for the Reader in examining the functional roles of microRNAs in the most diverse aspects of clinical practice, which will be explored in this third volume of the microRNA trilogy.

Exploiting microRNA Specificity and Selectivity: Paving a Sustainable Path Towards Precision Medicine

PubMed Central

2016-01-01

In his State of the Union address before both chambers of the US Congress, President Barack Obama called for increased investment in US infrastructure and research and announced the launch of a new Precision Medicine Initiative, aiming to accelerate biomedical discovery. Due to their well-established selectivity and specificity, microRNAs can represent a useful tool, both in diagnosis and therapy, in forging the path towards the achievement of precision medicine. This introductory chapter represents a guide for the Reader in examining the functional roles of microRNAs in the most diverse aspects of clinical practice, which will be explored in this third volume of the microRNA trilogy. PMID:26663175

A novel AFM-based 5-axis nanoscale machine tool for fabrication of nanostructures on a micro ball

NASA Astrophysics Data System (ADS)

Geng, Yanquan; Wang, Yuzhang; Yan, Yongda; Zhao, Xuesen

2017-11-01

This paper presents a novel atomic force microscopy (AFM)-based 5-axis nanoscale machine tool developed to fabricate nanostructures on different annuli of the micro ball. Different nanostructures can be obtained by combining the scratching trajectory of the AFM tip with the movement of the high precision air-bearing spindle. The center of the micro ball is aligned to be coincided with the gyration center of the high precision to guarantee the machining process during the rotating of the air-bearing spindle. Processing on different annuli of the micro ball is achieved by controlling the distance between the center of the micro ball and the rotation center of the AFM head. Nanostructures including square cavities, circular cavities, triangular cavities, and an annular nanochannel are machined successfully on the three different circumferences of a micro ball with a diameter of 1500 μm. Moreover, the influences of the error motions of the high precision air-bearing spindle and the eccentric between the micro ball and the gyration center of the high precision air-bearing spindle on the processing position error on the micro ball are also investigated. This proposed machining method has the potential to prepare the inertial confinement fusion target with the expected dimension defects, which would advance the application of the AFM tip-based nanomachining approach.

Benefits of Model Updating: A Case Study Using the Micro-Precision Interferometer Testbed

NASA Technical Reports Server (NTRS)

Neat, Gregory W.; Kissil, Andrew; Joshi, Sanjay S.

1997-01-01

This paper presents a case study on the benefits of model updating using the Micro-Precision Interferometer (MPI) testbed, a full-scale model of a future spaceborne optical interferometer located at JPL.

Isolation of guard cells from fresh epidermis using a piezo-power micro-dissection system with vibration-attenuated needles.

PubMed

Terpitz, Ulrich; Zimmermann, Dirk

2010-01-01

The Eppendorf Piezo-Power Microdissection (PPMD) system uses a tungsten needle (MicroChisel) oscillating in a forward-backward (vertical) mode to cut cells from surrounding tissue. This technology competes with laser-based dissection systems, which offer high accuracy and precision, but are more expensive and require fixed tissue. In contrast, PPMD systems can dissect freshly prepared tissue, but their accuracy and precision is lower due to unwanted lateral vibrations of the MicroChisel. Especially in tissues where elasticity is high, these vibrations can limit the cutting resolution or hamper the dissection. Here we describe a cost-efficient and simple glass capillary-encapsulation modification of MicroChisels for effective attenuation of lateral vibrations. The use of modified MicroChisels enables accurate and precise tissue dissection from highly elastic material.

A Contamination-Free Ultrahigh Precision Formation Flying Method for Micro-, Nano-, and Pico-Satellites with Nanometer Accuracy

NASA Astrophysics Data System (ADS)

Bae, Young K.

2006-01-01

Formation flying of clusters of micro-, nano- and pico-satellites has been recognized to be more affordable, robust and versatile than building a large monolithic satellite in implementing next generation space missions requiring large apertures or large sample collection areas and sophisticated earth imaging/monitoring. We propose a propellant free, thus contamination free, method that enables ultrahigh precision satellite formation flying with intersatellite distance accuracy of nm (10-9 m) at maximum estimated distances in the order of tens of km. The method is based on ultrahigh precision CW intracavity photon thrusters and tethers. The pushing-out force of the intracavity photon thruster and the pulling-in force of the tether tension between satellites form the basic force structure to stabilize crystalline-like structures of satellites and/or spacecrafts with a relative distance accuracy better than nm. The thrust of the photons can be amplified by up to tens of thousand times by bouncing them between two mirrors located separately on pairing satellites. For example, a 10 W photon thruster, suitable for micro-satellite applications, is theoretically capable of providing thrusts up to mN, and its weight and power consumption are estimated to be several kgs and tens of W, respectively. The dual usage of photon thruster as a precision laser source for the interferometric ranging system further simplifies the system architecture and minimizes the weight and power consumption. The present method does not require propellant, thus provides significant propulsion system mass savings, and is free from propellant exhaust contamination, ideal for missions that require large apertures composed of highly sensitive sensors. The system can be readily scaled down for the nano- and pico-satellite applications.

Polymer micromold and fabrication process

DOEpatents

Lee, Abraham P.; Northrup, M. Allen; Ahre, Paul E.; Dupuy, Peter C.

1997-01-01

A mold assembly with micro-sized features in which the hollow portion thereof is fabricated from a sacrificial mandrel which is surface treated and then coated to form an outer shell. The sacrificial mandrel is then selectively etched away leaving the outer shell as the final product. The sacrificial mandrel is fabricated by a precision lathe, for example, so that when removed by etching the inner or hollow area has diameters as small as 10's of micros (.mu.m). Varying the inside diameter contours of the mold can be accomplished with specified ramping slopes formed on the outer surface of the sacrificial mandrel, with the inside or hollow section being, for example, 275 .mu.m in length up to 150 .mu.m in diameter within a 6 mm outside diameter (o.d.) mold assembly. The mold assembly itself can serve as a micronozzle or microneedle, and plastic parts, such as microballoons for angioplasty, polymer microparts, and microactuators, etc., may be formed within the mold assembly.

A mechanically driven form of Kirigami as a route to 3D mesostructures in micro/nanomembranes

DOE PAGES

Zhang, Yihui; Yan, Zheng; Nan, Kewang; ...

2015-09-08

Assembly of 3D micro/nanostructures in advanced functional materials has important implications across broad areas of technology. Existing approaches are compatible, however, only with narrow classes of materials and/or 3D geometries. This article introduces ideas for a form of Kirigami that allows precise, mechanically driven assembly of 3D mesostructures of diverse materials from 2D micro/nanomembranes with strategically designed geometries and patterns of cuts. Theoretical and experimental studies demonstrate applicability of the methods across length scales from macro to nano, in materials ranging from monocrystalline silicon to plastic, with levels of topographical complexity that significantly exceed those that can be achieved usingmore » other approaches. A broad set of examples includes 3D silicon mesostructures and hybrid nanomembrane-nanoribbon systems, including heterogeneous combinations with polymers and metals, with critical dimensions that range from 100 nm to 30 mm. Lastly, a 3D mechanically tunable optical transmission window provides an application example of this Kirigami process, enabled by theoretically guided design.« less

Micro-precise spatiotemporal delivery system embedded in 3D printing for complex tissue regeneration.

PubMed

Tarafder, Solaiman; Koch, Alia; Jun, Yena; Chou, Conrad; Awadallah, Mary R; Lee, Chang H

2016-04-25

Three dimensional (3D) printing has emerged as an efficient tool for tissue engineering and regenerative medicine, given its advantages for constructing custom-designed scaffolds with tunable microstructure/physical properties. Here we developed a micro-precise spatiotemporal delivery system embedded in 3D printed scaffolds. PLGA microspheres (μS) were encapsulated with growth factors (GFs) and then embedded inside PCL microfibers that constitute custom-designed 3D scaffolds. Given the substantial difference in the melting points between PLGA and PCL and their low heat conductivity, μS were able to maintain its original structure while protecting GF's bioactivities. Micro-precise spatial control of multiple GFs was achieved by interchanging dispensing cartridges during a single printing process. Spatially controlled delivery of GFs, with a prolonged release, guided formation of multi-tissue interfaces from bone marrow derived mesenchymal stem/progenitor cells (MSCs). To investigate efficacy of the micro-precise delivery system embedded in 3D printed scaffold, temporomandibular joint (TMJ) disc scaffolds were fabricated with micro-precise spatiotemporal delivery of CTGF and TGFβ3, mimicking native-like multiphase fibrocartilage. In vitro, TMJ disc scaffolds spatially embedded with CTGF/TGFβ3-μS resulted in formation of multiphase fibrocartilaginous tissues from MSCs. In vivo, TMJ disc perforation was performed in rabbits, followed by implantation of CTGF/TGFβ3-μS-embedded scaffolds. After 4 wks, CTGF/TGFβ3-μS embedded scaffolds significantly improved healing of the perforated TMJ disc as compared to the degenerated TMJ disc in the control group with scaffold embedded with empty μS. In addition, CTGF/TGFβ3-μS embedded scaffolds significantly prevented arthritic changes on TMJ condyles. In conclusion, our micro-precise spatiotemporal delivery system embedded in 3D printing may serve as an efficient tool to regenerate complex and inhomogeneous tissues.

Silicon microfabricated beam expander

NASA Astrophysics Data System (ADS)

Othman, A.; Ibrahim, M. N.; Hamzah, I. H.; Sulaiman, A. A.; Ain, M. F.

2015-03-01

The feasibility design and development methods of silicon microfabricated beam expander are described. Silicon bulk micromachining fabrication technology is used in producing features of the structure. A high-precision complex 3-D shape of the expander can be formed by exploiting the predictable anisotropic wet etching characteristics of single-crystal silicon in aqueous Potassium-Hydroxide (KOH) solution. The beam-expander consist of two elements, a micromachined silicon reflector chamber and micro-Fresnel zone plate. The micro-Fresnel element is patterned using lithographic methods. The reflector chamber element has a depth of 40 µm, a diameter of 15 mm and gold-coated surfaces. The impact on the depth, diameter of the chamber and absorption for improved performance are discussed.

Electrochemical Micromachining with Fiber Laser Masking for 304 Stainless Steel

NASA Astrophysics Data System (ADS)

Li, Xiaohai; Wang, Shuming; Wang, Dong; Tong, Han

2017-10-01

In order to fabricate micro structure, the combined machining of electrochemical micro machining (EMM) and laser masking for 304 stainless steel was studied. A device of composite machining of EMM with laser masking was developed, and the experiments of EMM with laser masking were carried out. First, by marking pattern with fiber laser on the surface of 304 stainless steel, the special masking layer can be formed. Through X ray photoelectron spectroscopy (XPS), the corrosion resistance of laser masking layer was analyzed. It is proved by XPS that the iron oxide and chromium oxide on the surface of stainless steel generates due to air oxidation when laser scanning heats. Second, the localization and precision of EMM are improved, since the marking patterns forming on the surface of stainless steel by laser masking play a protective role in the process of subsequent EMM when the appropriate parameters of EMM are selected. At last, the shape and the roughness of the machined samples were measured by SEM and optical profilometer and analyzed. The results show that the rapid fabrication of micro structures on the 304 stainless steel surface can be achieved by EMM with fiber laser masking, which has a good prospect in the field of micro machining.

Bone remodeling in onlay beta-tricalcium phosphate and coral grafts to rat calvaria: microcomputerized tomography analysis.

PubMed

Anavi, Yakir; Avishai, Gal; Calderon, Shlomo; Allon, Dror M

2011-08-01

This study was conducted to establish the efficiency of microcomputerized tomography (micro-CT) in detection of trabecular bone remodeling of onlay grafts in a rodent calvaria model, and to compare bone remodeling after onlay grafts with beta-tricalcium phosphate (TCP) or coral calcium carbonate. Ten rats received calvarial onlay blocks-5 with TCP and 5 with coral calcium carbonate. The grafts were fixed with a titanium miniplate screw and were covered with a collagen resorbable membrane. Three months after surgery, the calvaria were segmented, and a serial 3-dimensional micro-CT scan of the calvarium and grafted bone block at 16-micrometer resolution was performed. Image analysis software was used to calculate the percentage of newly formed bone from the total block size. Newly formed bone was present adjacent to the calvarium and screw in all specimens. The mean area of newly formed bone of the total block size ranged from 34.67%-38.34% in the TCP blocks, and from 32.41%-34.72% in the coral blocks. In the TCP blocks, bone remodeling was found to be slightly higher than in the coral blocks. Micro-CT appears to be a precise, reproducible, specimen-nondestructive method of analysis of bone formation in onlay block grafts to rat calvaria.

Automated 3D bioassembly of micro-tissues for biofabrication of hybrid tissue engineered constructs.

PubMed

Mekhileri, N V; Lim, K S; Brown, G C J; Mutreja, I; Schon, B S; Hooper, G J; Woodfield, T B F

2018-01-12

Bottom-up biofabrication approaches combining micro-tissue fabrication techniques with extrusion-based 3D printing of thermoplastic polymer scaffolds are emerging strategies in tissue engineering. These biofabrication strategies support native self-assembly mechanisms observed in developmental stages of tissue or organoid growth as well as promoting cell-cell interactions and cell differentiation capacity. Few technologies have been developed to automate the precise assembly of micro-tissues or tissue modules into structural scaffolds. We describe an automated 3D bioassembly platform capable of fabricating simple hybrid constructs via a two-step bottom-up bioassembly strategy, as well as complex hybrid hierarchical constructs via a multistep bottom-up bioassembly strategy. The bioassembly system consisted of a fluidic-based singularisation and injection module incorporated into a commercial 3D bioprinter. The singularisation module delivers individual micro-tissues to an injection module, for insertion into precise locations within a 3D plotted scaffold. To demonstrate applicability for cartilage tissue engineering, human chondrocytes were isolated and micro-tissues of 1 mm diameter were generated utilising a high throughput 96-well plate format. Micro-tissues were singularised with an efficiency of 96.0 ± 5.1%. There was no significant difference in size, shape or viability of micro-tissues before and after automated singularisation and injection. A layer-by-layer approach or aforementioned bottom-up bioassembly strategy was employed to fabricate a bilayered construct by alternatively 3D plotting a thermoplastic (PEGT/PBT) polymer scaffold and inserting pre-differentiated chondrogenic micro-tissues or cell-laden gelatin-based (GelMA) hydrogel micro-spheres, both formed via high-throughput fabrication techniques. No significant difference in viability between the construct assembled utilising the automated bioassembly system and manually assembled construct was observed. Bioassembly of pre-differentiated micro-tissues as well as chondrocyte-laden hydrogel micro-spheres demonstrated the flexibility of the platform while supporting tissue fusion, long-term cell viability, and deposition of cartilage-specific extracellular matrix proteins. This technology provides an automated and scalable pathway for bioassembly of both simple and complex 3D tissue constructs of clinically relevant shape and size, with demonstrated capability to facilitate direct spatial organisation and hierarchical 3D assembly of micro-tissue modules, ranging from biomaterial free cell pellets to cell-laden hydrogel formulations.

Relocation of micro-earthquakes in the Yeongdeok offshore area, Korea using local and Ocean bottom seismometers

NASA Astrophysics Data System (ADS)

HAN, M.; Kim, K. H.; Park, S. C.; Lin, P. P.; Chen, P.; Chang, H.; Jang, J. P.; Kuo, B. Y.; Liao, Y. C.

2016-12-01

Seismicity in the East Sea of Korea has been relatively high during the last four decades of instrumental earthquake observation period. Yeongdeok offshore area is probably the most seismically active area in the East Sea. This study analyzes seismic signals to detect micro-earthquakes and determine their precise earthquake hypocenters in the Yeoungdeok offshore area using data recorded by the Korea National Seismic Network (KNSN) and a temporary ocean bottom seismographic network (OBSN-PNU) operated by Korea Meteorological Administration and Pusan National University, respectively. Continuous waveform data recorded at four seismic stations in the study area of KNSN between January 2007 and July 2016 are inspected to detect any repeating earthquakes by applying a waveform cross-correlation detector. More than 1,600 events are triggered. Events outside the study area or in poor waveform quality are removed from further analysis. Approximately 500 earthquakes are selected, most of which have gone unreported because their magnitudes are lower than the detection threshold of the routine earthquake monitoring. Events in the study area are also under bad azimuthal coverage because all stations are located on land and thus biased to the west. OBSN-PNU comprised three ocean bottom seismometers and operated to observe micro-earthquakes in the study area between February and August 2016. The same technique applied to the KNSN data has been applied to the OBSN-PNU data to detect micro-earthquakes. Precise earthquake hypocenters are determined using phase arrival times and waveform similarities. Resultant hypocenters are clustered to form a few lineaments. They are compared to the local geological and geophysical features to understand micro-earthquake activity in the area.

Grinding aspheric and freeform micro-optical molds

NASA Astrophysics Data System (ADS)

Tohme, Yazid E.

2007-02-01

Fueled by the need for better performing optics, glass optics are now replacing plastic optics in many industrial and consumer electronic devices. One of these devices is the mobile phone camera. The optical sub-assembly in a mobile phone includes several micro lenses that are spherical and/or aspherical in shape and require form tolerances in the submicron range. These micro glass lenses are mass produced by a replication process known as glass press molding. The process entails the compression of a glass gob between two precise optical quality molds at an elevated temperature, usually near the transition temperature of the glass material. The elevated forces and temperatures required in the glass molding process limits the materials of the molds to very tough materials such as tungsten carbide or silicon carbide. These materials can withstand large pressing forces at high temperatures without any significant deformation. These materials offer great mechanical properties for glass press molding but they are also a challenge to machine to submicron accuracy. The work in this paper discusses a deterministic micro grinding manufacturing process referred to as wheel normal grinding, which is utilized to produce these optical quality molds. Wheel normal grinding is more accurate and more deterministic than most other grinding techniques and can produce molds to the form and finish tolerances required for optical molding. This method relies on the ability to recognize and compensate for grinding wheel wear and machine repeatable errors. Results will be presented to illustrate the accuracy of this micro grinding technique.

Pre-stressed piezoelectric bimorph micro-actuators based on machined 40 µm PZT thick films: batch scale fabrication and integration with MEMS

NASA Astrophysics Data System (ADS)

Wilson, S. A.; Jourdain, R. P.; Owens, S.

2010-09-01

The projected force-displacement capability of piezoelectric ceramic films in the 20-50 µm thickness range suggests that they are well suited to many micro-fluidic and micro-pneumatic applications. Furthermore when they are configured as bending actuators and operated at ~ 1 V µm - 1 they do not necessarily conform to the high-voltage, very low-displacement piezoelectric stereotype. Even so they are rarely found today in commercial micro-electromechanical devices, such as micro-pumps and micro-valves, and the main barriers to making them much more widely available would appear to be processing incompatibilities rather than commercial desirability. In particular, the issues associated with integration of these devices into MEMS at the production level are highly significant and they have perhaps received less attention in the mainstream than they deserve. This paper describes a fabrication route based on ultra-precision ceramic machining and full-wafer bonding for cost-effective batch scale production of thick film PZT bimorph micro-actuators and their integration with MEMS. The resulting actuators are pre-stressed (ceramic in compression) which gives them added performance, they are true bimorphs with bi-directional capability and they exhibit full bulk piezoelectric ceramic properties. The devices are designed to integrate with ancillary systems components using transfer-bonding techniques. The work forms part of the European Framework 6 Project 'Q2M—Quality to Micro'.

Bubble-on-fiber (BoF): a built-in tunable broadband acousto-optic sensor for liquid-immersible in situ measurements.

PubMed

Xu, Hongsong; Wang, Guanyu; Ma, Jun; Jin, Long; Oh, Kyunghwan; Guan, Bai-Ou

2018-04-30

A new type of tunable broadband fiber-optic acousto-optic sensor was experimentally demonstrated by utilizing a bubble-on-fiber (BoF) interferometer. A single micro-bubble was generated by injecting a heating laser at λ = 980 nm on the metalized facet of an optical fiber. The BoF formed a spherical micro-cavity in water whose acoustic deformation was precisely detected by using a narrowband DFB laser at 1550 nm. The heating light and the interrogating light were fed into a single fiber probe by wavelength division multiplexing (WDM) realizing a small footprint all-fiber configuration. The diameter of the BoF was stabilized with a variation less than 0.5 nm by fast servo-control of the heating laser power. The stabilized BoF served as a Fabry-Pérot cavity that can be deformed by acoustic perturbation, and a minimum detectable pressure level of as low as ~1 mPa/Hz 1/2 was achieved in a frequency range of over 60 kHz in water at room temperature. Our proposed BoF technology can provide a tunable, flexible and all-fiber solution to detect minute acoustically driven perturbations combining high-precision interferometry. Due to the very small form-factor, the technique can find applications of liquid-immersible in situ measurements in bio-molecular/cell detection and biochemical phenomena study.

Ionization Electron Signal Processing in Single Phase LArTPCs II. Data/Simulation Comparison and Performance in MicroBooNE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adams, C.; et al.

The single-phase liquid argon time projection chamber (LArTPC) provides a large amount of detailed information in the form of fine-grained drifted ionization charge from particle traces. To fully utilize this information, the deposited charge must be accurately extracted from the raw digitized waveforms via a robust signal processing chain. Enabled by the ultra-low noise levels associated with cryogenic electronics in the MicroBooNE detector, the precise extraction of ionization charge from the induction wire planes in a single-phase LArTPC is qualitatively demonstrated on MicroBooNE data with event display images, and quantitatively demonstrated via waveform-level and track-level metrics. Improved performance of inductionmore » plane calorimetry is demonstrated through the agreement of extracted ionization charge measurements across different wire planes for various event topologies. In addition to the comprehensive waveform-level comparison of data and simulation, a calibration of the cryogenic electronics response is presented and solutions to various MicroBooNE-specific TPC issues are discussed. This work presents an important improvement in LArTPC signal processing, the foundation of reconstruction and therefore physics analyses in MicroBooNE.« less

Fabrication of unique 3D microparticles in non-rectangular microchannels with flow lithography

NASA Astrophysics Data System (ADS)

Nam, Sung Min; Kim, Kibeom; Park, Wook; Lee, Wonhee

Invention of flow lithography has offered a simple yet effective method of fabricating micro-particles. However particles produced with conventional techniques were largely limited to 2-dimensional shapes projected to form a column. We proposed inexpensive and simple soft-lithography techniques to fabricate micro-channels with various cross-sectional shapes. The non-rectangular channels are then used to fabricate micro-particles using flow lithography resulting in interesting 3D shapes such as tetrahedrals or half-pyramids. In addition, a microfluidic device capable of fabricating multi-layered micro-particles was developed. On-chip PDMS valves are used to trap and position the particle at the precise location in microchannel with varying cross-section. Multilayer particles are generated by sequential monomer exchange and polymerization along the channel. While conventional multi-layered particles made with droplet generators require their layer materials be dissolved in immiscible fluids, the new method allows diverse choice of materials, not limited to their diffusibility. The multilayer 3D particles can be applied in areas such as drug delivery and tissue engineering.

Ultraprecision finishing of micro-aspherical surface by ultrasonic assisted polishing; Technical Digest

NASA Astrophysics Data System (ADS)

Suzuki, Hirofumi; Kawamori, Ryota; Yamamoto, Yuji; Miyabara, Mitsuru; Okino, Tadashi; Hijikata, Yoshio; Moriwaki, Toshimichi

2005-05-01

Micro aspherical glass lenses are required for electronic devices, optical devices and advanced optical fiber transmission equipments. The glass lenses are manufactured by glass molding method by using micro ceramics dies such as tungsten carbide or silicon carbide (1). Therefore molding dies are most important and they were ground by ultra-precision grinding method with diamond wheel. Recently, the wavelength of used laser is becoming shorter and then the accuracies of the micro molding die are required to be much more precise (2). In this paper, ultrasonic assisted polishing methods/systems were developed in order to finish micro aspherical dies that were ground with micro diamond wheel. In the polishing experiments, the molding die of tungsten carbide was polished with diamond abrasives to test the basic polishing characteristics and the aspheric die was polished with proposed ultrasonic assisted polishing method.

Nano-stepper-driven optical shutter for applications in free-space micro-optics

NASA Astrophysics Data System (ADS)

Zawadzka, Justyna; Li, Lijie; Unamuno, Anartz; Uttamchandani, Deepak G.

2002-09-01

In this paper we report a simple design of a micro-optical shutter/attenuator. The standard MUMPS process was used to fabricate the device. A vertically erected, gold-coated, 200x300 mm side length micro-mirror was precisely placed between the end faces of two closely spaced optical fibers. The position of the micro-mirror with respect to the optical fiber end face was controlled by a nano-stepping motor array. Optical and mechanical tests were performed on the device. A 1.55 mm laser beam was sent along the optical fiber. When the micro-mirror was removed from the front of the fiber, the coupling efficiency between two fibers was -10 dBm. Once the micro-mirror was placed in the optical path the coupling efficiency dropped to -51.5 dBm. The best attenuation was obtained when the micro-mirror blocked the whole cross-section of the laser beam diameter. It is evident that the device can operate as a high precision fiber optic attenuator or shutter.

MicroRNA applications for prostate, ovarian and breast cancer in the era of precision medicine

PubMed Central

Smith, Bethany; Agarwal, Priyanka

2017-01-01

The high degree of conservation in microRNA from Caenorhabditis elegans to humans has enabled relatively rapid implementation of findings in model systems to the clinic. The convergence of the capacity for genomic screening being implemented in the prevailing precision medicine initiative and the capabilities of microRNA to address these changes holds significant promise. However, prostate, ovarian and breast cancers are heterogeneous and face issues of evolving therapeutic resistance. The transforming growth factor-beta (TGFβ) signaling axis plays an important role in the progression of these cancers by regulating microRNAs. Reciprocally, microRNAs regulate TGFβ actions during cancer progression. One must consider the expression of miRNA in the tumor microenvironment a source of biomarkers of disease progression and a viable target for therapeutic targeting. The differential expression pattern of microRNAs in health and disease, therapeutic response and resistance has resulted in its application as robust biomarkers. With two microRNA mimetics in ongoing restorative clinical trials, the paradigm for future clinical studies rests on the current observational trials to validate microRNA markers of disease progression. Some of today’s biomarkers can be translated to the next generation of microRNA-based therapies. PMID:28289080

Precision laser processing for micro electronics and fiber optic manufacturing

NASA Astrophysics Data System (ADS)

Webb, Andrew; Osborne, Mike; Foster-Turner, Gideon; Dinkel, Duane W.

2008-02-01

The application of laser based materials processing for precision micro scale manufacturing in the electronics and fiber optic industry is becoming increasingly widespread and accepted. This presentation will review latest laser technologies available and discuss the issues to be considered in choosing the most appropriate laser and processing parameters. High repetition rate, short duration pulsed lasers have improved rapidly in recent years in terms of both performance and reliability enabling flexible, cost effective processing of many material types including metal, silicon, plastic, ceramic and glass. Demonstrating the relevance of laser micromachining, application examples where laser processing is in use for production will be presented, including miniaturization of surface mount capacitors by applying a laser technique for demetalization of tracks in the capacitor manufacturing process and high quality laser machining of fiber optics including stripping, cleaving and lensing, resulting in optical quality finishes without the need for traditional polishing. Applications include telecoms, biomedical and sensing. OpTek Systems was formed in 2000 and provide fully integrated systems and sub contract services for laser processes. They are headquartered in the UK and are establishing a presence in North America through a laser processing facility in South Carolina and sales office in the North East.

A minimally invasive micro sampler for quantitative sampling with an ultrahigh-aspect-ratio microneedle and a PDMS actuator.

PubMed

Liu, Long; Wang, Yan; Yao, Jinyuan; Yang, Cuijun; Ding, Guifu

2016-08-01

This study describes a novel micro sampler consisting of an ultrahigh-aspect-ratio microneedle and a PDMS actuator. The microneedle was fabricated by a new method which introduced reshaped photoresist technology to form a flow channel inside. The microneedle includes two parts: shaft and pedestal. In this study, the shaft length is 1500 μm with a 45° taper angle on the tip and pedestal is 1000 μm. Besides, the shaft and pedestal are connected by an arc connection structure with a length of 600 μm. The microneedles have sufficient mechanical strength to insert into skin with a wide safety margin which was proved by mechanics tests. Moreover, a PDMS actuator with a chamber inside was designed and fabricated in this study. The chamber, acting as a reservoir in sampling process as well as providing power, was optimized by finite element analysis (FEA) to decrease dead volume and improve sampling precision. The micro sampler just needs finger press to activate the sampling process as well as used for quantitative micro injection to some extent. And a volume of 31.5 ± 0.8 μl blood was successfully sampled from the ear artery of a rabbit. This micro sampler is suitable for micro sampling for diagnose or therapy in biomedical field.

Detection of bio-signature by microscopy and mass spectrometry

NASA Astrophysics Data System (ADS)

Tulej, M.; Wiesendanger, R.; Neuland, M., B.; Meyer, S.; Wurz, P.; Neubeck, A.; Ivarsson, M.; Riedo, V.; Moreno-Garcia, P.; Riedo, A.; Knopp, G.

2017-09-01

We demonstrate detection of micro-sized fossilized bacteria by means of microscopy and mass spectrometry. The characteristic structures of lifelike forms are visualized with a micrometre spatial resolution and mass spectrometric analyses deliver elemental and isotope composition of host and fossilized materials. Our studies show that high selectivity in isolation of fossilized material from host phase can be achieved while applying a microscope visualization (location), a laser ablation ion source with sufficiently small laser spot size and applying depth profiling method. Our investigations shows that fossilized features can be well isolated from host phase. The mass spectrometric measurements can be conducted with sufficiently high accuracy and precision yielding quantitative elemental and isotope composition of micro-sized objects. The current performance of the instrument allows the measurement of the isotope fractionation in per mill level and yield exclusively definition of the origin of the investigated species by combining optical visualization of investigated samples (morphology and texture), chemical characterization of host and embedded in the host micro-sized structure. Our isotope analyses involved bio-relevant B, C, S, and Ni isotopes which could be measured with sufficiently accuracy to conclude about the nature of the micro-sized objects.

Decoupled macro/micro-manipulator for fast and precise assembly operations: design and experiments

NASA Astrophysics Data System (ADS)

Hodac, Agathe; Siegwart, Roland Y.

1999-08-01

This paper presents a high performance single arm robot configuration, based on a macro-manipulator coupled with a micro-manipulator. The system is well suited to fast and precise positioning tasks for repetitive pick and place applications in the manufacturing industry. Firstly, the paper focuses on the design of the micro-manipulator, particularly on the selection of the proper micro-actuator type and location. We show that the micro-manipulator's design with an actuator placed between endpoint and ground and with a flexible suspension system can reduce the dynamic coupling between the macro-manipulator and the micro- manipulator. The overall system performance can then be improved. We describe two different designs of compact and fast micro-manipulators composed of voice coil actuators and a monolithic flexure suspension with notch hinges. Secondly, the paper presents a control strategy that allows both correction of possible misalignments of the end-effector relative to the target and compensation of tip oscillations. The dynamic interaction is analyzed and stability is verified. Finally, experimental results demonstrate significant improvements in acceleration, endpoint accuracy and settling time achieved by the novel configuration of the macro/micro-manipulator.

Invited article: Dielectric material characterization techniques and designs of high-Q resonators for applications from micro to millimeter-waves frequencies applicable at room and cryogenic temperatures.

PubMed

Le Floch, Jean-Michel; Fan, Y; Humbert, Georges; Shan, Qingxiao; Férachou, Denis; Bara-Maillet, Romain; Aubourg, Michel; Hartnett, John G; Madrangeas, Valerie; Cros, Dominique; Blondy, Jean-Marc; Krupka, Jerzy; Tobar, Michael E

2014-03-01

Dielectric resonators are key elements in many applications in micro to millimeter wave circuits, including ultra-narrow band filters and frequency-determining components for precision frequency synthesis. Distributed-layered and bulk low-loss crystalline and polycrystalline dielectric structures have become very important for building these devices. Proper design requires careful electromagnetic characterization of low-loss material properties. This includes exact simulation with precision numerical software and precise measurements of resonant modes. For example, we have developed the Whispering Gallery mode technique for microwave applications, which has now become the standard for characterizing low-loss structures. This paper will give some of the most common characterization techniques used in the micro to millimeter wave regime at room and cryogenic temperatures for designing high-Q dielectric loaded cavities.

Investigations on the micro-scale surface interactions at the tool and workpiece interface in micro-manufacturing of bipolar plates for proton exchange membrane fuel cells

NASA Astrophysics Data System (ADS)

Peker, Mevlut Fatih

Micro-forming studies have been more attractive in recent years because of miniaturization trend. One of the promising metal forming processes, micro-stamping, provides durability, strength, surface finish, and low cost for metal products. Hence, it is considered a prominent method for fabricating bipolar plates (BPP) with micro-channel arrays on large metallic surfaces to be used in Proton Exchange Membrane Fuel Cells (PEMFC). Major concerns in micro-stamping of high volume BPPs are surface interactions between micro-stamping dies and blank metal plates, and tribological changes. These concerns play a critical role in determining the surface quality, channel formation, and dimensional precision of bipolar plates. The surface quality of BPP is highly dependent on the micro-stamping die surface, and process conditions due to large ratios of surface area to volume (size effect) that cause an increased level of friction and wear issues at the contact interface. Due to the high volume and fast production rates, BPP surface characteristics such as surface roughness, hardness, and stiffness may change because of repeated interactions between tool (micro-forming die) and workpiece (sheet blank of interest). Since the surface characteristics of BPPs have a strong effect on corrosion and contact resistance of bipolar plates, and consequently overall fuel cell performance, evolution of surface characteristics at the tool and workpiece should be monitored, controlled, and kept in acceptable ranges throughout the long production cycles to maintain the surface quality. Compared to macro-forming operations, tribological changes in micro-forming process are bigger challenges due to their dominance and criticality. Therefore, tribological size effect should be considered for better understanding of tribological changes in micro-scale. The integrity of process simulation to the experiments, on the other hand, is essential. This study describes an approach that aims to investigate the surface topography changes during long-run micro-stamping of BPPs, and establish relationships between surface roughness--corrosion resistance and surface roughness-contact resistance characteristics of BPPs. Formability levels of formed BPPs and repeatability characteristics of the process were investigated. In addition, blank thickness changes, von-Mises stress, plastic strain levels and distributions of micro-stamping process were determined via finite element analysis (FEA). Test results revealed that the surface roughness change for the stamping dies and BPPs was unsteady (no trend) due to the continuous change of surface topography (i.e. asperity deformation). Sub-micron range local plastic deformations on stamping dies led to surface topography changes on BPP in long-run manufacturing case. As surface defects trigger corrosion, the correlation between surface roughness and corrosion resistance of BPPs was found to be direct. Increasing number of surface irregularities (asperities) lowered contact surface area that resulted in increased contact resistance. ZrN coated BPPs, on the other hand, did not change surface roughness, however; it improved the protection of BPPs against corrosion significantly. In addition, ZrN coating increased the conductivity of BPPs and reduced the contact resistance between BPP and gas diffusion layer (GDL), at certain extent. As dimensional stability and repeatability was confirmed in forming of both uncoated and coated BPPs during the long run manufacturing, different formability levels were achieved for coated and uncoated samples. Lower channel height values were obtained for coated plates because of the different surface hardness of uncoated and coated plates. In tribological size effect part of study, micro stamping experiments using three different dies with distinct channel height values at different stamping force levels were performed. It was concluded that decrease in forming die dimensions led to increase in coefficient of friction as previously reported by other researchers as one of the consequences of tribological size effect. On the other hand, coefficient of friction values were not affected by the force levels used in the experiments and simulations, whereas plastic strain, equivalent stress, and formability levels were increased with increasing stamping force, as expected. In essence, this study proposed a methodology to investigate the long-run manufacturing effects on dimensional stability and surface characteristics of micro-stamped sheets. It also correlates these parameters to fuel cell performance measures such as interfacial contact and corrosion resistance.

Laser-directed 3D assembly of carbon nanotubes using two-photon polymerization (Conference Presentation)

NASA Astrophysics Data System (ADS)

Liu, Ying; Xiong, Wei; Jiang, Li Jia; Zhou, Yunshen; Li, Dawei; Jiang, Lan; Silvain, Jean-Francois; Lu, Yongfeng

2017-02-01

Precise assembly of carbon nanotubes (CNTs) in arbitrary 3D space with proper alignment is critically important and desirable for CNT applications but still remains as a long-standing challenge. Using the two-photon polymerization (TPP) technique, it is possible to fabricate 3D micro/nanoscale CNT/polymer architectures with proper CNT alignments in desired directions, which is expected to enable a broad range of applications of CNTs in functional devices. To unleash the full potential of CNTs, it is strategically important to develop TPP-compatible resins with high CNT concentrations for precise assembly of CNTs into 3D micro/nanostructures for functional device applications. We investigated a thiol grafting method in functionalizing multiwalled carbon nanotubes (MWNTs) to develop TPP-compatible MWNT-thiol-acrylate (MTA) composite resins. The composite resins developed had high MWNT concentrations up to 0.2 wt%, over one order of magnitude higher than previously published work. Significantly enhanced electrical and mechanical properties of the 3D micro/nanostructures were achieved. Precisely controlled MWNT assembly and strong anisotropic effects were confirmed. Microelectronic devices made of the MTA composite polymer were demonstrated. The nanofabrication method can achieve controlled assembly of MWNTs in 3D micro/nanostructures, enabling a broad range of CNT applications, including 3D electronics, integrated photonics, and micro/nanoelectromechanical systems (MEMS/NEMS).

TAPIR, a web server for the prediction of plant microRNA targets, including target mimics.

PubMed

Bonnet, Eric; He, Ying; Billiau, Kenny; Van de Peer, Yves

2010-06-15

We present a new web server called TAPIR, designed for the prediction of plant microRNA targets. The server offers the possibility to search for plant miRNA targets using a fast and a precise algorithm. The precise option is much slower but guarantees to find less perfectly paired miRNA-target duplexes. Furthermore, the precise option allows the prediction of target mimics, which are characterized by a miRNA-target duplex having a large loop, making them undetectable by traditional tools. The TAPIR web server can be accessed at: http://bioinformatics.psb.ugent.be/webtools/tapir. Supplementary data are available at Bioinformatics online.

Microfabricated X-Ray Optics Technology Development for the Constellation-X Mission

NASA Technical Reports Server (NTRS)

Schattenburg, Mark L.

2003-01-01

During the period of this Cooperative Agreement, MIT developed advanced methods for applying silicon micro-stuctures for the precision assembly of foil x-ray optics in support of the Constellution-X Spectroscopy X-ray Telescope (SXT) development effort at Goddard Space Flight Center (GSFC). MIT developed improved methods for fabricating and characterizing the precision silicon micro-combs. MIT also developed and characterized assembly tools and several types of metrology tools in order to characterize and reduce the errors associated with precision assembly of foil optics. Results of this effort were published and presented to the scientific community and the GSFC SXT team.

Practical alignment method for X-ray spectral measurement in micro-CT system based on 3D printing technology.

PubMed

Ren, Liqiang; Wu, Di; Li, Yuhua; Zheng, Bin; Chen, Yong; Yang, Kai; Liu, Hong

2016-06-01

This study presents a practical alignment method for X-ray spectral measurement in a rotating gantry based micro-computed tomography (micro-CT) system using three-dimensional (3D) printing technology. In order to facilitate the spectrometer placement inside the gantry, supporting structures including a cover and a stand were dedicatedly designed and printed using a 3D printer. According to the relative position between the spectrometer and the stand, the upright projection of the spectrometer collimator onto the stand was determined and then marked by a tungsten pinhole. Thus, a visible alignment indicator of the X-ray central beam and the spectrometer collimator represented by the pinhole was established in the micro-CT live mode. Then, a rough alignment could be achieved through repeatedly adjusting and imaging the stand until the pinhole was located at the center of the acquired projection image. With the spectrometer being positioned back onto the stand, the precise alignment was completed by slightly translating the spectrometer-stand assembly around the rough location, until finding a "sweet spot" with the highest photon rate and proper distribution of the X-ray photons in the resultant spectrum. The spectra were acquired under precise alignment and misalignment of approximately 0.2, 0.5, and 1.0mm away from the precise alignment position, and then were compared in qualitative and quantitative analyses. Qualitative analysis results show that, with slight misalignment, the photon rate is reduced from 1302 to 1098, 1031, and 416 photons/second (p/s), respectively, and the characteristic peaks in the acquired spectra are gradually deteriorated. Quantitative analysis indicates that the energy resolutions for characteristic peak of K α1 were calculated as 1.56% for precise alignment, while were 1.84% and 2.40% for slight misalignment of 0.2mm and 0.5mm. The mean energies were reduced from 43.93keV under precise alignment condition to 40.97, 39.63 and 37.78keV when misaligned. Accurate spectral measurements in micro-CT systems are significantly influenced by the alignment precision. This practical alignment method using 3D printing technology could be readily applied to other rotating gantry based micro-CT systems with modified design of the supporting structures and careful considerations of the spectrometer and gantry dimensions.

Practical alignment method for X-ray spectral measurement in micro-CT system based on 3D printing technology

PubMed Central

Ren, Liqiang; Wu, Di; Li, Yuhua; Zheng, Bin; Chen, Yong; Yang, Kai; Liu, Hong

2016-01-01

This study presents a practical alignment method for X-ray spectral measurement in a rotating gantry based micro-computed tomography (micro-CT) system using three-dimensional (3D) printing technology. In order to facilitate the spectrometer placement inside the gantry, supporting structures including a cover and a stand were dedicatedly designed and printed using a 3D printer. According to the relative position between the spectrometer and the stand, the upright projection of the spectrometer collimator onto the stand was determined and then marked by a tungsten pinhole. Thus, a visible alignment indicator of the X-ray central beam and the spectrometer collimator represented by the pinhole was established in the micro-CT live mode. Then, a rough alignment could be achieved through repeatedly adjusting and imaging the stand until the pinhole was located at the center of the acquired projection image. With the spectrometer being positioned back onto the stand, the precise alignment was completed by slightly translating the spectrometer-stand assembly around the rough location, until finding a “sweet spot” with the highest photon rate and proper distribution of the X-ray photons in the resultant spectrum. The spectra were acquired under precise alignment and misalignment of approximately 0.2, 0.5, and 1.0mm away from the precise alignment position, and then were compared in qualitative and quantitative analyses. Qualitative analysis results show that, with slight misalignment, the photon rate is reduced from 1302 to 1098, 1031, and 416 photons/second (p/s), respectively, and the characteristic peaks in the acquired spectra are gradually deteriorated. Quantitative analysis indicates that the energy resolutions for characteristic peak of Kα1 were calculated as 1.56% for precise alignment, while were 1.84% and 2.40% for slight misalignment of 0.2mm and 0.5mm. The mean energies were reduced from 43.93keV under precise alignment condition to 40.97, 39.63 and 37.78keV when misaligned. Accurate spectral measurements in micro-CT systems are significantly influenced by the alignment precision. This practical alignment method using 3D printing technology could be readily applied to other rotating gantry based micro-CT systems with modified design of the supporting structures and careful considerations of the spectrometer and gantry dimensions. PMID:27777787

Study on digital closed-loop system of silicon resonant micro-sensor

NASA Astrophysics Data System (ADS)

Xu, Yefeng; He, Mengke

2008-10-01

Designing a micro, high reliability weak signal extracting system is a critical problem need to be solved in the application of silicon resonant micro-sensor. The closed-loop testing system based on FPGA uses software to replace hardware circuit which dramatically decrease the system's mass and power consumption and make the system more compact, both correlation theory and frequency scanning scheme are used in extracting weak signal, the adaptive frequency scanning arithmetic ensures the system real-time. The error model was analyzed to show the solution to enhance the system's measurement precision. The experiment results show that the closed-loop testing system based on FPGA has the personality of low power consumption, high precision, high-speed, real-time etc, and also the system is suitable for different kinds of Silicon Resonant Micro-sensor.

Effective Light Directed Assembly of Building Blocks with Microscale Control.

PubMed

Dinh, Ngoc-Duy; Luo, Rongcong; Christine, Maria Tankeh Asuncion; Lin, Weikang Nicholas; Shih, Wei-Chuan; Goh, James Cho-Hong; Chen, Chia-Hung

2017-06-01

Light-directed forces have been widely used to pattern micro/nanoscale objects with precise control, forming functional assemblies. However, a substantial laser intensity is required to generate sufficient optical gradient forces to move a small object in a certain direction, causing limited throughput for applications. A high-throughput light-directed assembly is demonstrated as a printing technology by introducing gold nanorods to induce thermal convection flows that move microparticles (diameter = 40 µm to several hundreds of micrometers) to specific light-guided locations, forming desired patterns. With the advantage of effective light-directed assembly, the microfluidic-fabricated monodispersed biocompatible microparticles are used as building blocks to construct a structured assembly (≈10 cm scale) in ≈2 min. The control with microscale precision is approached by changing the size of the laser light spot. After crosslinking assembly of building blocks, a novel soft material with wanted pattern is approached. To demonstrate its application, the mesenchymal stem-cell-seeded hydrogel microparticles are prepared as functional building blocks to construct scaffold-free tissues with desired structures. This light-directed fabrication method can be applied to integrate different building units, enabling the bottom-up formation of materials with precise control over their internal structure for bioprinting, tissue engineering, and advanced manufacturing. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Micro-combs: A novel generation of optical sources

NASA Astrophysics Data System (ADS)

Pasquazi, Alessia; Peccianti, Marco; Razzari, Luca; Moss, David J.; Coen, Stéphane; Erkintalo, Miro; Chembo, Yanne K.; Hansson, Tobias; Wabnitz, Stefan; Del'Haye, Pascal; Xue, Xiaoxiao; Weiner, Andrew M.; Morandotti, Roberto

2018-01-01

The quest towards the integration of ultra-fast, high-precision optical clocks is reflected in the large number of high-impact papers on the topic published in the last few years. This interest has been catalysed by the impact that high-precision optical frequency combs (OFCs) have had on metrology and spectroscopy in the last decade [1-5]. OFCs are often referred to as optical rulers: their spectra consist of a precise sequence of discrete and equally-spaced spectral lines that represent precise marks in frequency. Their importance was recognised worldwide with the 2005 Nobel Prize being awarded to T.W. Hänsch and J. Hall for their breakthrough in OFC science [5]. They demonstrated that a coherent OFC source with a large spectrum - covering at least one octave - can be stabilised with a self-referenced approach, where the frequency and the phase do not vary and are completely determined by the source physical parameters. These fully stabilised OFCs solved the challenge of directly measuring optical frequencies and are now exploited as the most accurate time references available, ready to replace the current standard for time. Very recent advancements in the fabrication technology of optical micro-cavities [6] are contributing to the development of OFC sources. These efforts may open up the way to realise ultra-fast and stable optical clocks and pulsed sources with extremely high repetition-rates, in the form of compact and integrated devices. Indeed, the fabrication of high-quality factor (high-Q) micro-resonators, capable of dramatically amplifying the optical field, can be considered a photonics breakthrough that has boosted not only the scientific investigation of OFC sources [7-13] but also of optical sensors and compact light modulators [6,14]. In this framework, the demonstration of planar high-Q resonators, compatible with silicon technology [10-14], has opened up a unique opportunity for these devices to provide entirely new capabilities for photonic-integrated technologies. Indeed, it is well acknowledged by the electronics industry that future generations of computer processing chips will inevitably require an extremely high density of copper-based interconnections, significantly increasing the chip power dissipation to beyond practical levels [15-17]; hence, conventional approaches to chip design must undergo radical changes. On-chip optical networks, or optical interconnects, can offer high speed and low energy per-transferred-bit, and micro-resonators are widely seen as a key component to interface the electronic world with photonics. Many information technology industries have recently focused on the development of integrated ring resonators to be employed for electrically-controlled light modulators [14-17], greatly advancing the maturity of micro-resonator technology as a whole. Recently [11-13], the demonstration of OFC sources in micro-resonators fabricated in electronic (i.e. in complementary metal oxide semiconductor (CMOS)) compatible platforms has given micro-cavities an additional appeal, with the possibility of exploiting them as light sources in microchips. This scenario is creating fierce competition in developing highly efficient OFC generators based on micro-cavities which can radically change the nature of information transport and processing. Even in telecommunications, perhaps a more conventional environment for optical technologies, novel time-division multiplexed optical systems will require extremely stable optical clocks at ultra-high pulse repetition-rates towards the THz scale. Furthermore, arbitrary pulse generators based on OFC [18,19] are seen as one of the most promising solutions for this next generation of high-capacity optical coherent communication systems. This review will summarise the recent exciting achievements in the field of micro-combs, namely optical frequency combs based on high-Q micro-resonators, with a perspective on both the potential of this technology, as well as the open questions and challenges that remain.

Micro- and nanoengineering for stem cell biology: the promise with a caution.

PubMed

Kshitiz; Kim, Deok-Ho; Beebe, David J; Levchenko, Andre

2011-08-01

Current techniques used in stem cell research only crudely mimic the physiological complexity of the stem cell niches. Recent advances in the field of micro- and nanoengineering have brought an array of in vitro cell culture models that have enabled development of novel, highly precise and standardized tools that capture physiological details in a single platform, with greater control, consistency, and throughput. In this review, we describe the micro- and nanotechnology-driven modern toolkit for stem cell biologists to design novel experiments in more physiological microenvironments with increased precision and standardization, and caution them against potential challenges that the modern technologies might present. Copyright © 2011 Elsevier Ltd. All rights reserved.

Large-scale fabrication of micro-lens array by novel end-fly-cutting-servo diamond machining.

PubMed

Zhu, Zhiwei; To, Suet; Zhang, Shaojian

2015-08-10

Fast/slow tool servo (FTS/STS) diamond turning is a very promising technique for the generation of micro-lens array (MLA). However, it is still a challenge to process MLA in large scale due to certain inherent limitations of this technique. In the present study, a novel ultra-precision diamond cutting method, as the end-fly-cutting-servo (EFCS) system, is adopted and investigated for large-scale generation of MLA. After a detailed discussion of the characteristic advantages for processing MLA, the optimal toolpath generation strategy for the EFCS is developed with consideration of the geometry and installation pose of the diamond tool. A typical aspheric MLA over a large area is experimentally fabricated, and the resulting form accuracy, surface micro-topography and machining efficiency are critically investigated. The result indicates that the MLA with homogeneous quality over the whole area is obtained. Besides, high machining efficiency, extremely small volume of control points for the toolpath, and optimal usage of system dynamics of the machine tool during the whole cutting can be simultaneously achieved.

Actuation control of a PiezoMEMS biomimetic robotic jellyfish

NASA Astrophysics Data System (ADS)

Alejandre, Alvaro; Olszewski, Oskar; Jackson, Nathan

2017-06-01

Biomimetic micro-robots try to mimic the motion of a living system in the form of a synthetically developed microfabricated device. Dynamic motion of living systems have evolved through the years, but trying to mimic these motions is challenging. Micro-robotics are particular challenging as the fabrication of devices and controlling the motion in 3 dimensions is difficult. However, micro-scale robotics have potential to be used in a wide range of applications. MEMS based robots that can move and function in a liquid environment is of particular interest. This paper describes the development of a piezoMEMS based device that mimics the movement of a jellyfish. The paper focuses on the development of a finite element model that investigates a method of controlling the individual piezoelectric beams in order to create a jet propulsion motion, consisting of a quick excitation pulse followed by a slow recovery pulse in order to maximize thrust and velocity. By controlling the individual beams or legs of the jellyfish robot the authors can control the robot to move precisely in 3 dimensions.

Performance evaluation of the microINR® point-of-care INR-testing system.

PubMed

Joubert, J; van Zyl, M C; Raubenheimer, J

2018-04-01

Point-of-care International Normalised Ratio (INR) testing is used frequently. We evaluated the microINR ® POC system for accuracy, precision and measurement repeatability, and investigated instrument and test chip variability and error rates. Venous blood INRs of 210 patients on warfarin were obtained with Thromborel ® S on the Sysmex CS-2100i ® analyser and compared with capillary blood microINR ® values. Precision was assessed using control materials. Measurement repeatability was calculated on 51 duplicate finger-prick INRs. Triplicate finger-prick INRs using three different instruments (30 patients) and three different test chip lots (29 patients) were used to evaluate instrument and test chip variability. Linear regression analysis of microINR ® and Sysmex CS2100i ® values showed a correlation coefficient of 0.96 (P < .0001) and a positive proportional bias of 4.4%. Dosage concordance was 93.8% and clinical agreement 95.7%. All acceptance criteria based on ISO standard 17593:2007 system accuracy requirements were met. Control material coefficients of variation (CV) varied from 6.2% to 16.7%. The capillary blood measurement repeatability CV was 7.5%. No significant instrument (P = .93) or test chip (P = .81) variability was found, and the error rate was low (2.8%). The microINR ® instrument is accurate and precise for monitoring warfarin therapy. © 2017 John Wiley & Sons Ltd.

Micro-miniature gas chromatograph column disposed in silicon wafers

DOEpatents

Yu, Conrad M.

2000-01-01

A micro-miniature gas chromatograph column is fabricated by forming matching halves of a circular cross-section spiral microcapillary in two silicon wafers and then bonding the two wafers together using visual or physical alignment methods. Heating wires are deposited on the outside surfaces of each wafer in a spiral or serpentine pattern large enough in area to cover the whole microcapillary area inside the joined wafers. The visual alignment method includes etching through an alignment window in one wafer and a precision-matching alignment target in the other wafer. The two wafers are then bonded together using the window and target. The physical alignment methods include etching through vertical alignment holes in both wafers and then using pins or posts through corresponding vertical alignment holes to force precision alignment during bonding. The pins or posts may be withdrawn after curing of the bond. Once the wafers are bonded together, a solid phase of very pure silicone is injected in a solution of very pure chloroform into one end of the microcapillary. The chloroform lowers the viscosity of the silicone enough that a high pressure hypodermic needle with a thumbscrew plunger can force the solution into the whole length of the spiral microcapillary. The chloroform is then evaporated out slowly to leave the silicone behind in a deposit.

Low-cost, high-precision micro-lensed optical fiber providing deep-micrometer to deep-nanometer-level light focusing.

PubMed

Wen, Sy-Bor; Sundaram, Vijay M; McBride, Daniel; Yang, Yu

2016-04-15

A new type of micro-lensed optical fiber through stacking appropriate high-refractive microspheres at designed locations with respect to the cleaved end of an optical fiber is numerically and experimentally demonstrated. This new type of micro-lensed optical fiber can be precisely constructed with low cost and high speed. Deep micrometer-scale and submicrometer-scale far-field light spots can be achieved when the optical fibers are multimode and single mode, respectively. By placing an appropriate teardrop dielectric nanoscale scatterer at the far-field spot of this new type of micro-lensed optical fiber, a deep-nanometer near-field spot can also be generated with high intensity and minimum joule heating, which is valuable in high-speed, high-resolution, and high-power nanoscale detection compared with traditional near-field optical fibers containing a significant portion of metallic material.

TU-H-CAMPUS-TeP2-03: High Sensitivity and High Resolution Fiber Based Micro-Detector for Sub-Millimeter Preclinical Dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Izaguirre, E; Pokhrel, S; Knewtson, T

2016-06-15

Purpose: Current precision of small animal and cell micro-irradiators has continuously increased during the past years. Currently, preclinical irradiators can deliver sub-millimeter fields with micrometric precision but there are no water equivalent dosimeters to determine small field profiles and dose in the orthovoltage range of energies with micrometric resolution and precision. We have developed a fiber based micro-dosimeter with the resolution and dosimetric accuracy required for radiobiological research. Methods: We constructed two prototypes of micro-dosimeters based on different compositions of fiber scintillators to study the spatial resolution and dosimetric precision of small animal and cell micro-irradiators. The first has greenmore » output and the second has blue output. The blue output dosimeter has the highest sensitivity because it matches the spectral sensitivity of silicon photomultipliers. A blue detector with 500um cross section was built and tested respect to a CC01 ion chamber, film, and the 1500um green output detector. Orthovoltage fields from 1×1mm2 to 5×5mm2 were used for detector characteristics comparison. Results: The blue fiber dosimeter shows great agreement with films and matches dose measurements with the gold-standard ion chamber for 5×5mm2 fields. The detector has the appropriate sensitivity to measure fields from 1×1mm2 to larger sizes with a 1% dosimetric accuracy. The spatial resolution is in the sub-millimeter range and the spectral matching with the photomultiplier allows reducing the sensor cross section even further than the presented prototype. These results suggest that scintillating fibers combined with silicon photomultipliers is the appropriate technology to pursue micro-dosimetry for small animals and disperse cell samples. Conclusion: The constructed detectors establish a new landmark for the resolution and sensitivity of fiber based microdetectors. The validation of the detector in our small animal and cell irradiator shows that they are appropriate for preclinical and micro single cell irradiation quality assurance and dosimetry.« less

Micro axial tomography: A miniaturized, versatile stage device to overcome resolution anisotropy in fluorescence light microscopy

NASA Astrophysics Data System (ADS)

Staier, Florian; Eipel, Heinz; Matula, Petr; Evsikov, Alexei V.; Kozubek, Michal; Cremer, Christoph; Hausmann, Michael

2011-09-01

With the development of novel fluorescence techniques, high resolution light microscopy has become a challenging technique for investigations of the three-dimensional (3D) micro-cosmos in cells and sub-cellular components. So far, all fluorescence microscopes applied for 3D imaging in biosciences show a spatially anisotropic point spread function resulting in an anisotropic optical resolution or point localization precision. To overcome this shortcoming, micro axial tomography was suggested which allows object tilting on the microscopic stage and leads to an improvement in localization precision and spatial resolution. Here, we present a miniaturized device which can be implemented in a motor driven microscope stage. The footprint of this device corresponds to a standard microscope slide. A special glass fiber can manually be adjusted in the object space of the microscope lens. A stepwise fiber rotation can be controlled by a miniaturized stepping motor incorporated into the device. By means of a special mounting device, test particles were fixed onto glass fibers, optically localized with high precision, and automatically rotated to obtain views from different perspective angles under which distances of corresponding pairs of objects were determined. From these angle dependent distance values, the real 3D distance was calculated with a precision in the ten nanometer range (corresponding here to an optical resolution of 10-30 nm) using standard microscopic equipment. As a proof of concept, the spindle apparatus of a mature mouse oocyte was imaged during metaphase II meiotic arrest under different perspectives. Only very few images registered under different rotation angles are sufficient for full 3D reconstruction. The results indicate the principal advantage of the micro axial tomography approach for many microscopic setups therein and also those of improved resolutions as obtained by high precision localization determination.

Alveolar Ridge Augmentation with Three-Dimensional Printed Hydroxyapatite Devices: A Preclinical Study.

PubMed

Fiorellini, Joseph P; Norton, Michael R; Luan, Kevin WanXin; Kim, David Minjoon; Wada, Kei; Sarmiento, Hector L

2018-02-14

The objective of this study was to evaluate the effectiveness of precise three-dimensional hydroxyapatite printed micro- and macrochannel devices for alveolar ridge augmentation in a canine model. All grafts induced minimal inflammatory and fibrotic reactions. Examination of undecalcified sections revealed that both types of grafts demonstrated bone ingrowth. The majority of the bone growth into the block graft was into the channels, though a portion grew directly into the construct in the form of small bony spicules. In conclusion, bone ingrowth was readily demonstrated in the middle of the implanted printed devices.

Single-anchor support and supercritical CO2 drying enable high-precision microfabrication of three-dimensional structures.

PubMed

Maruo, Shoji; Hasegawa, Takuya; Yoshimura, Naoki

2009-11-09

In high-precision two-photon microfabrication of three-dimensional (3-D) polymeric microstructures, supercritical CO(2) drying was employed to reduce surface tension, which tends to cause the collapse of micro/nano structures. Use of supercritical drying allowed high-aspect ratio microstructures, such as micropillars and cantilevers, to be fabricated. We also propose a single-anchor supporting method to eliminate non-uniform shrinkage of polymeric structures otherwise caused by attachment to the substrate. Use of this method permitted frame models such as lattices to be produced without harmful distortion. The combination of supercritical CO(2) drying and the single-anchor supporting method offers reliable high-precision microfabrication of sophisticated, fragile 3-D micro/nano structures.

Sensor-Based Inspection of the Formation Accuracy in Ultra-Precision Grinding (UPG) of Aspheric Surface Considering the Chatter Vibration

NASA Astrophysics Data System (ADS)

Lei, Yao; Bai, Yue; Xu, Zhijun

2018-06-01

This paper proposes an experimental approach for monitoring and inspection of the formation accuracy in ultra-precision grinding (UPG) with respect to the chatter vibration. Two factors related to the grinding progress, the grinding speed of grinding wheel and spindle, and the oil pressure of the hydrostatic bearing are taken into account to determining the accuracy. In the meantime, a mathematical model of the radius deviation caused by the micro vibration is also established and applied in the experiments. The results show that the accuracy is sensitive to the vibration and the forming accuracy is much improved with proper processing parameters. It is found that the accuracy of aspheric surface can be less than 4 μm when the grinding speed is 1400 r/min and the wheel speed is 100 r/min with the oil pressure being 1.1 MPa.

Absolute quantification by droplet digital PCR versus analog real-time PCR

PubMed Central

Hindson, Christopher M; Chevillet, John R; Briggs, Hilary A; Gallichotte, Emily N; Ruf, Ingrid K; Hindson, Benjamin J; Vessella, Robert L; Tewari, Muneesh

2014-01-01

Nanoliter-sized droplet technology paired with digital PCR (ddPCR) holds promise for highly precise, absolute nucleic acid quantification. Our comparison of microRNA quantification by ddPCR and real-time PCR revealed greater precision (coefficients of variation decreased by 37–86%) and improved day-to-day reproducibility (by a factor of seven) of ddPCR but with comparable sensitivity. When we applied ddPCR to serum microRNA biomarker analysis, this translated to superior diagnostic performance for identifying individuals with cancer. PMID:23995387

Posttranscriptional control of neuronal development by microRNA networks.

PubMed

Gao, Fen-Biao

2008-01-01

The proper development of the nervous system requires precise spatial and temporal control of gene expression at both the transcriptional and translational levels. In different experimental model systems, microRNAs (miRNAs) - a class of small, endogenous, noncoding RNAs that control the translation and stability of many mRNAs - are emerging as important regulators of various aspects of neuronal development. Further dissection of the in vivo physiological functions of individual miRNAs promises to offer novel mechanistic insights into the gene regulatory networks that ensure the precise assembly of a functional nervous system.

Precise deformation measurement of prestressed concrete beam during a strain test using the combination of intersection photogrammetry and micro-network measurement

NASA Astrophysics Data System (ADS)

Urban, Rudolf; Braun, Jaroslav; Štroner, Martin

2015-05-01

The prestressed thin-walled concrete elements enable the bridge a relatively large span. These structures are advantageous in economic and environmental way due to their thickness and lower consumption of materials. The bending moments can be effectively influenced by using the pre-stress. The experiment was done to monitor deformation of the under load. During the experiment the discrete points were monitored. To determine a large number of points, the intersection photogrammetry combined with precise micro-network were chosen. Keywords:

High-precision micro/nano-scale machining system

DOEpatents

Kapoor, Shiv G.; Bourne, Keith Allen; DeVor, Richard E.

2014-08-19

A high precision micro/nanoscale machining system. A multi-axis movement machine provides relative movement along multiple axes between a workpiece and a tool holder. A cutting tool is disposed on a flexible cantilever held by the tool holder, the tool holder being movable to provide at least two of the axes to set the angle and distance of the cutting tool relative to the workpiece. A feedback control system uses measurement of deflection of the cantilever during cutting to maintain a desired cantilever deflection and hence a desired load on the cutting tool.

Dimensional measurement of micro parts with high aspect ratio in HIT-UOI

NASA Astrophysics Data System (ADS)

Dang, Hong; Cui, Jiwen; Feng, Kunpeng; Li, Junying; Zhao, Shiyuan; Zhang, Haoran; Tan, Jiubin

2016-11-01

Micro parts with high aspect ratios have been widely used in different fields including aerospace and defense industries, while the dimensional measurement of these micro parts becomes a challenge in the field of precision measurement and instrument. To deal with this contradiction, several probes for the micro parts precision measurement have been proposed by researchers in Center of Ultra-precision Optoelectronic Instrument (UOI), Harbin Institute of Technology (HIT). In this paper, optical fiber probes with structures of spherical coupling(SC) with double optical fibers, micro focal-length collimation (MFL-collimation) and fiber Bragg grating (FBG) are described in detail. After introducing the sensing principles, both advantages and disadvantages of these probes are analyzed respectively. In order to improve the performances of these probes, several approaches are proposed. A two-dimensional orthogonal path arrangement is propounded to enhance the dimensional measurement ability of MFL-collimation probes, while a high resolution and response speed interrogation method based on differential method is used to improve the accuracy and dynamic characteristics of the FBG probes. The experiments for these special structural fiber probes are given with a focus on the characteristics of these probes, and engineering applications will also be presented to prove the availability of them. In order to improve the accuracy and the instantaneity of the engineering applications, several techniques are used in probe integration. The effectiveness of these fiber probes were therefore verified through both the analysis and experiments.

Development of ultra-precision micro-cavity measurement technique in HIT-UOI

NASA Astrophysics Data System (ADS)

Cui, Jiwen; Li, Lei; Tan, Jiubin

2010-08-01

Micro cavities with high aspect ratio are widely used in different fields including aerospace and defense industries with the development of manufacturing technology. So how to measure the dimension of these cavities has become one of the major research subjects in the field of measurement and instrument. This paper describes some activities of the precision micro cavity measurement technique in Center of Ultra-precision Optoelectronic Instrument (UOI), Harbin Institute of Technology (HIT). The key issue of micro cavity measurement in UOI is called touch-trigger measurement method. The first scheme is double optical fiber coupling, in which light coming from the incident optical fiber is transmitted in the reversal direction via the optical fiber coupling into the effluent optical fiber, the lateral displacement of the touch-trigger sensor is transformed into the deflexion of light coming out from the effluent optical fiber, and the deflexion is transformed into an image signal by the object lens and CCD capturing system. And the second scheme is micro focal-length collimation, in which a fiber stem with a ball mounted on its end is used as a probe and a small segment of it is used as a cylindrical lens to collimate a point light source and image it to a camera, the deflection of the fiber stem can be inferred from the change in image acquired by the camera with ultrahigh displacement sensitivity. Experiments for these activities will be given with a focus on the measurement results and repeatability uncertainty.

Optical versus tactile geometry measurement: alternatives or counterparts

NASA Astrophysics Data System (ADS)

Lehmann, Peter

2003-05-01

This contribution deals with measuring strategies and methods for the determination of several geometrical features, covering the surface micro-topography and the form of mechanical objects. The measuring principles used in optical surface metrology include optical focusing profilers, confocal point measuring and areal measuring sensors as well as interferometrical principles such as white light interferometry and speckle techniques. In comparison with stylus instruments optical techniques provide certain advantages such as a fast data acquisition, in-process applicability or contactless measurement. However, the frequency response characteristics of optical and tactile measurement differ significantly. In addition, optical sensors are commonly more influenced by critical geometrical conditions and optical properties of an object. For precise form measurement mechanical instruments dominate till now. One reason for this may be, that commonly the complete 360 degrees geometry of the measuring object has to be analyzed. Another point is that optical principles such as form measuring interferometry fail in cases of complex object geometry or rougher object surfaces. Other methods, e.g. fringe projection or digital holography, till now do not meet the accuracy demands of precision engineered workpieces. Hence, a combination of mechanical concepts and optical sensors represents an interesting potential for current and future measuring tasks, which require high accuracy and maximum flexibility.

Role of endocortical contouring methods on precision of HR-pQCT-derived cortical micro-architecture in postmenopausal women and young adults.

PubMed

Kawalilak, C E; Johnston, J D; Cooper, D M L; Olszynski, W P; Kontulainen, S A

2016-02-01

Precision errors of cortical bone micro-architecture from high-resolution peripheral quantitative computed tomography (pQCT) ranged from 1 to 16 % and did not differ between automatic or manually modified endocortical contour methods in postmenopausal women or young adults. In postmenopausal women, manually modified contours led to generally higher cortical bone properties when compared to the automated method. First, the objective of the study was to define in vivo precision errors (coefficient of variation root mean square (CV%RMS)) and least significant change (LSC) for cortical bone micro-architecture using two endocortical contouring methods: automatic (AUTO) and manually modified (MOD) in two groups (postmenopausal women and young adults) from high-resolution pQCT (HR-pQCT) scans. Second, it was to compare precision errors and bone outcomes obtained with both methods within and between groups. Using HR-pQCT, we scanned twice the distal radius and tibia of 34 postmenopausal women (mean age ± SD 74 ± 7 years) and 30 young adults (27 ± 9 years). Cortical micro-architecture was determined using AUTO and MOD contour methods. CV%RMS and LSC were calculated. Repeated measures and multivariate ANOVA were used to compare mean CV% and bone outcomes between the methods within and between the groups. Significance was accepted at P < 0.05. CV%RMS ranged from 0.9 to 16.3 %. Within-group precision did not differ between evaluation methods. Compared to young adults, postmenopausal women had better precision for radial cortical porosity (precision difference 9.3 %) and pore volume (7.5 %) with MOD. Young adults had better precision for cortical thickness (0.8 %, MOD) and tibial cortical density (0.2 %, AUTO). In postmenopausal women, MOD resulted in 0.2-54 % higher values for most cortical outcomes, as well as 6-8 % lower radial and tibial cortical BMD and 2 % lower tibial cortical thickness. Results suggest that AUTO and MOD endocortical contour methods provide comparable repeatability. In postmenopausal women, manual modification of endocortical contours led to generally higher cortical bone properties when compared to the automated method, while no between-method differences were observed in young adults.

Precise positioning method for multi-process connecting based on binocular vision

NASA Astrophysics Data System (ADS)

Liu, Wei; Ding, Lichao; Zhao, Kai; Li, Xiao; Wang, Ling; Jia, Zhenyuan

2016-01-01

With the rapid development of aviation and aerospace, the demand for metal coating parts such as antenna reflector, eddy-current sensor and signal transmitter, etc. is more and more urgent. Such parts with varied feature dimensions, complex three-dimensional structures, and high geometric accuracy are generally fabricated by the combination of different manufacturing technology. However, it is difficult to ensure the machining precision because of the connection error between different processing methods. Therefore, a precise positioning method is proposed based on binocular micro stereo vision in this paper. Firstly, a novel and efficient camera calibration method for stereoscopic microscope is presented to solve the problems of narrow view field, small depth of focus and too many nonlinear distortions. Secondly, the extraction algorithms for law curve and free curve are given, and the spatial position relationship between the micro vision system and the machining system is determined accurately. Thirdly, a precise positioning system based on micro stereovision is set up and then embedded in a CNC machining experiment platform. Finally, the verification experiment of the positioning accuracy is conducted and the experimental results indicated that the average errors of the proposed method in the X and Y directions are 2.250 μm and 1.777 μm, respectively.

Study on the Automatic Detection Method and System of Multifunctional Hydrocephalus Shunt

NASA Astrophysics Data System (ADS)

Sun, Xuan; Wang, Guangzhen; Dong, Quancheng; Li, Yuzhong

2017-07-01

Aiming to the difficulty of micro pressure detection and the difficulty of micro flow control in the testing process of hydrocephalus shunt, the principle of the shunt performance detection was analyzed.In this study, the author analyzed the principle of several items of shunt performance detection,and used advanced micro pressure sensor and micro flow peristaltic pump to overcome the micro pressure detection and micro flow control technology.At the same time,This study also puted many common experimental projects integrated, and successfully developed the automatic detection system for a shunt performance detection function, to achieve a test with high precision, high efficiency and automation.

Measurement of material mechanical properties in microforming

NASA Astrophysics Data System (ADS)

Yun, Wang; Xu, Zhenying; Hui, Huang; Zhou, Jianzhong

2006-02-01

As the rapid market need of micro-electro-mechanical systems engineering gives it the wide development and application ranging from mobile phones to medical apparatus, the need of metal micro-parts is increasing gradually. Microforming technology challenges the plastic processing technology. The findings have shown that if the grain size of the specimen remains constant, the flow stress changes with the increasing miniaturization, and also the necking elongation and the uniform elongation etc. It is impossible to get the specimen material properties in conventional tensile test machine, especially in the high precision demand. Therefore, one new measurement method for getting the specimen material-mechanical property with high precision is initiated. With this method, coupled with the high speed of Charge Coupled Device (CCD) camera and high precision of Coordinate Measuring Machine (CMM), the elongation and tensile strain in the gauge length are obtained. The elongation, yield stress and other mechanical properties can be calculated from the relationship between the images and CCD camera movement. This measuring method can be extended into other experiments, such as the alignment of the tool and specimen, micro-drawing process.

Mesoplasticity approach to studies of the cutting mechanism in ultra-precision machining

NASA Astrophysics Data System (ADS)

Lee, Rongbin W. B.; Wang, Hao; To, Suet; Cheung, Chi Fai; Chan, Chang Yuen

2014-03-01

There have been various theoretical attempts by researchers worldwide to link up different scales of plasticity studies from the nano-, micro- and macro-scale of observation, based on molecular dynamics, crystal plasticity and continuum mechanics. Very few attempts, however, have been reported in ultra-precision machining studies. A mesoplasticity approach advocated by Lee and Yang is adopted by the authors and is successfully applied to studies of the micro-cutting mechanisms in ultra-precision machining. Traditionally, the shear angle in metal cutting, as well as the cutting force variation, can only be determined from cutting tests. In the pioneering work of the authors, the use of mesoplasticity theory enables prediction of the fluctuation of the shear angle and micro-cutting force, shear band formation, chip morphology in diamond turning and size effect in nano-indentation. These findings are verified by experiments. The mesoplasticity formulation opens up a new direction of studies to enable how the plastic behaviour of materials and their constitutive representations in deformation processing, such as machining can be predicted, assessed and deduced from the basic properties of the materials measurable at the microscale.

New micro-beam beamline at SPring-8, targeting at protein micro-crystallography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hirata, Kunio; Ueno, Go; Nisawa, Atsushi

2010-06-23

A new protein micro-crystallography beamline BL32XU at SPring-8 is under construction and scheduled to start operation in 2010. The beamline is designed to provide the stabilized and brilliant micro-beam to collect high-quality data from micro-crystals. The beamline consists of a hybrid in-vacuum undulator, a liquid-nitrogen cooled double crystal monochromator, and K-B focusing mirrors with large magnification factor. Development of data acquisition system and end station consists of high-precision diffractometer, high-efficiency area detector, sample auto-changer etc. are also in progress.

Analysis of Fringe Field Formed Inside LDA Measurement Volume Using Compact Two Hololens Imaging Systems

NASA Astrophysics Data System (ADS)

Ghosh, Abhijit; Nirala, A. K.; Yadav, H. L.

2018-03-01

We have designed and fabricated four LDA optical setups consisting of aberration compensated four different compact two hololens imaging systems. We have experimentally investigated and realized a hololens recording geometry which is interferogram of converging spherical wavefront with mutually coherent planar wavefront. Proposed real time monitoring and actual fringe field analysis techniques allow complete characterizations of fringes formed at measurement volume and permit to evaluate beam quality, alignment and fringe uniformity with greater precision. After experimentally analyzing the fringes formed at measurement volume by all four imaging systems, it is found that fringes obtained using compact two hololens imaging systems get improved both qualitatively and quantitatively compared to that obtained using conventional imaging system. Results indicate qualitative improvement of non-uniformity in fringe thickness and micro intensity variations perpendicular to the fringes, and quantitative improvement of 39.25% in overall average normalized standard deviations of fringe width formed by compact two hololens imaging systems compare to that of conventional imaging system.

Challenges in mold manufacturing for high precision molded diffractive optical elements

NASA Astrophysics Data System (ADS)

Pongs, Guido; Bresseler, Bernd; Schweizer, Klaus; Bergs, Thomas

2016-09-01

Isothermal precision glass molding of imaging optics is the key technology for mass production of precise optical elements. Especially for numerous consumer applications (e.g. digital cameras, smart phones, …), high precision glass molding is applied for the manufacturing of aspherical lenses. The usage of diffractive optical elements (DOEs) can help to further reduce the number of lenses in the optical systems which will lead to a reduced weight of hand-held optical devices. But today the application of molded glass DOEs is limited due to the technological challenges in structuring the mold surfaces. Depending on the application submicrometer structures are required on the mold surface. Furthermore these structures have to be replicated very precisely to the glass lens surface. Especially the micro structuring of hard and brittle mold materials such as Tungsten Carbide is very difficult and not established. Thus a multitude of innovative approaches using diffractive optical elements cannot be realized. Aixtooling has investigated in different mold materials and different suitable machining technologies for the micro- and sub-micrometer structuring of mold surfaces. The focus of the work lays on ultra-precision grinding to generate the diffractive pattern on the mold surfaces. This paper presents the latest achievements in diffractive structuring of Tungsten Carbide mold surfaces by ultra-precision grinding.

A laboratory method for precisely determining the micro-volume-magnitudes of liquid efflux

NASA Technical Reports Server (NTRS)

Cloutier, R. L.

1969-01-01

Micro-volumetric quantities of ejected liquid are made to produce equal volumetric displacements of a more dense material. Weight measurements are obtained on the displaced heavier liquid and used to calculate volumes based upon the known density of the heavy medium.

Rapid prototyping of interfacing microcomponents for printed circuit board-level optical interconnects

NASA Astrophysics Data System (ADS)

Van Erps, Jürgen; Vervaeke, Michael; Thienpont, Hugo

2012-01-01

One of the important challenges for the deployment of the emerging breed of nanotechnology components is interfacing them with the external world, preferably accomplished with low-cost micro-optical devices. For the fabrication of this kind of micro-optical components, we make use of deep proton writing (DPW) as a generic rapid prototyping technology. DPW consists of bombarding polymer samples with swift protons, which results after chemical processing steps in high quality micro-optical components. The strength of the DPW micro-machining technology is the ability to fabricate monolithic building blocks that include micro-optical and mechanical functionalities which can be precisely integrated into more complex photonic systems. In this paper we give an overview of the process steps of the technology and we present several examples of micro-optical and micro-mechanical components, fabricated through DPW, targeting applications in printed circuit baordlevel optical interconnections. These include: high-precision 2-D fiber connectors, discrete out-of-plane coupling structures featuring high-quality 45° and curved micro-mirrors, arrays of high aspect ratio micro-pillars and backplane connectors. While DPW is clearly not a mass fabrication technique as such, one of its assets is that once the master component has been prototyped, a metal mould can be generated from the DPW master by applying electroplating. After removal of the plastic master, this metal mould can be used as a shim in a final microinjection moulding or hot embossing step. This way, the master component can be mass-produced at low cost in a wide variety of high-tech plastics.

Lotus-on-chip: computer-aided design and 3D direct laser writing of bioinspired surfaces for controlling the wettability of materials and devices.

PubMed

Lantada, Andrés Díaz; Hengsbach, Stefan; Bade, Klaus

2017-10-16

In this study we present the combination of a math-based design strategy with direct laser writing as high-precision technology for promoting solid free-form fabrication of multi-scale biomimetic surfaces. Results show a remarkable control of surface topography and wettability properties. Different examples of surfaces inspired on the lotus leaf, which to our knowledge are obtained for the first time following a computer-aided design with this degree of precision, are presented. Design and manufacturing strategies towards microfluidic systems whose fluid driving capabilities are obtained just by promoting a design-controlled wettability of their surfaces, are also discussed and illustrated by means of conceptual proofs. According to our experience, the synergies between the presented computer-aided design strategy and the capabilities of direct laser writing, supported by innovative writing strategies to promote final size while maintaining high precision, constitute a relevant step forward towards materials and devices with design-controlled multi-scale and micro-structured surfaces for advanced functionalities. To our knowledge, the surface geometry of the lotus leaf, which has relevant industrial applications thanks to its hydrophobic and self-cleaning behavior, has not yet been adequately modeled and manufactured in an additive way with the degree of precision that we present here.

Developing Performance Estimates for High Precision Astrometry with TMT

NASA Astrophysics Data System (ADS)

Schoeck, Matthias; Do, Tuan; Ellerbroek, Brent; Herriot, Glen; Meyer, Leo; Suzuki, Ryuji; Wang, Lianqi; Yelda, Sylvana

2013-12-01

Adaptive optics on Extremely Large Telescopes will open up many new science cases or expand existing science into regimes unattainable with the current generation of telescopes. One example of this is high-precision astrometry, which has requirements in the range from 10 to 50 micro-arc-seconds for some instruments and science cases. Achieving these requirements imposes stringent constraints on the design of the entire observatory, but also on the calibration procedures, observing sequences and the data analysis techniques. This paper summarizes our efforts to develop a top down astrometry error budget for TMT. It is predominantly developed for the first-light AO system, NFIRAOS, and the IRIS instrument, but many terms are applicable to other configurations as well. Astrometry error sources are divided into 5 categories: Reference source and catalog errors, atmospheric refraction correction errors, other residual atmospheric effects, opto-mechanical errors and focal plane measurement errors. Results are developed in parametric form whenever possible. However, almost every error term in the error budget depends on the details of the astrometry observations, such as whether absolute or differential astrometry is the goal, whether one observes a sparse or crowded field, what the time scales of interest are, etc. Thus, it is not possible to develop a single error budget that applies to all science cases and separate budgets are developed and detailed for key astrometric observations. Our error budget is consistent with the requirements for differential astrometry of tens of micro-arc-seconds for certain science cases. While no show stoppers have been found, the work has resulted in several modifications to the NFIRAOS optical surface specifications and reference source design that will help improve the achievable astrometry precision even further.

A robust rotation-invariance displacement measurement method for a micro-/nano-positioning system

NASA Astrophysics Data System (ADS)

Zhang, Xiang; Zhang, Xianmin; Wu, Heng; Li, Hai; Gan, Jinqiang

2018-05-01

A robust and high-precision displacement measurement method for a compliant mechanism-based micro-/nano-positioning system is proposed. The method is composed of an integer-pixel and a sub-pixel matching procedure. In the proposed algorithm (Pro-A), an improved ring projection transform (IRPT) and gradient information are used as features for approximating the coarse candidates and fine locations, respectively. Simulations are conducted and the results show that the Pro-A has the ability of rotation-invariance and strong robustness, with a theoretical accuracy of 0.01 pixel. To validate the practical performance, a series of experiments are carried out using a computer micro-vision and laser interferometer system (LIMS). The results demonstrate that both the LIMS and Pro-A can achieve high precision, while the Pro-A has better stability and adaptability.

Precision machining of advanced materials with waterjets

NASA Astrophysics Data System (ADS)

Liu, H. T.

2017-01-01

Recent advances in abrasive waterjet technology have elevated to the state that it often competes on equal footing with lasers and EDM for precision machining. Under the support of a National Science Foundation SBIR Phase II grant, OMAX has developed and commercialized micro abrasive water technology that is incorporated into a MicroMAX® JetMa- chining® Center. Waterjet technology, combined both abrasive waterjet and micro abrasive waterjet technology, is capable of machining most materials from macro to micro scales for a wide range of part size and thickness. Waterjet technology has technological and manufacturing merits that cannot be matched by most existing tools. As a cold cutting tool that creates no heat-affected zone, for example, waterjet cuts much faster than wire EDM and laser when measures to minimize a heat-affected zone are taken into account. In addition, waterjet is material independent; it cuts materials that cannot be cut or are difficult to cut otherwise. The versatility of waterjet has also demonstrated machining simulated nanomaterials with large gradients of material properties from metal, nonmetal, to anything in between. This paper presents waterjet-machined samples made of a wide range of advanced materials from macro to micro scales.

Use of Micro-CT and Precision Cutting to Assess Meteorite Heterogeneity: An Example Using Brachinite NWA 4872

NASA Astrophysics Data System (ADS)

Hyde, B. C.; Tait, K. T.; Nicklin, I.; Day, J. M. D.; Ash, R. D.; Moser, D. E.

2013-09-01

Sectioning of meteorites is usually done in an arbitrary manner. We used micro-computed tomography to view the interior of brachinite NWA 4872. A cut was then made through an area of interest. Heterogeneity and modal abundance are discussed.

Does thermal ecology influence dynamics of side-blotched lizards and their micro-parasites?

PubMed

Paranjpe, Dhanashree A; Medina, Dianna; Nielsen, Erica; Cooper, Robert D; Paranjpe, Sharayu A; Sinervo, Barry

2014-07-01

Hosts and parasites form interacting populations that influence each other in multiple ways. Their dynamics can also be influenced by environmental and ecological factors. We studied host-parasite dynamics in a previously unexplored study system: side-blotched lizards and their micro-parasites. Compared with uninfected lizards, the infected lizards elected to bask at lower temperatures that were outside their range of preferred temperatures. Infected lizards also were not as precise as uninfected lizards in maintaining their body temperatures within a narrow range. At the ecological scale, areas with higher infection rates coincided with more thermally heterogeneous microhabitats as well as with the areas where lizards tended to live longer. Thermal heterogeneity of lizards' microhabitats may provide important clues to the spatial and temporal distribution of infections. © The Author 2014. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

Aging effect on Zn retention on a calcareous soil: column experiments and synchrotron X-ray micro-spectroscopic investigation.

PubMed

Sayen, Stéphanie; Guillon, Emmanuel

2014-07-15

In this study, a combination of column experiments and micro-analytical techniques exploiting synchrotron generated X-rays was used to assess the effect of aging time on Zn retention and mobility in the specific case of calcareous soils (high pH value, ≈ 8). The samples were subjected to aging for 2, 6, 17, and 63 days. Freshly added Zn mainly existed as an exchangeable form, and this metal fraction decreased over time due to Zn redistribution to stronger binding sites. Thus, after aging for 63 days, 45% of Zn is remobilized from exchangeable sites to stronger binding sites. μ-XRF maps were used to find correlations among elements in the sample, and μ-XANES spectra were recorded to precise Zn speciation. These analyses evidenced an increasing partitioning of Zn from organic matter to iron oxy(hydr)oxides over time. The occurrence of hydrozincite is evidenced in all samples. Copyright © 2014 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Yihui; Yan, Zheng; Nan, Kewang

Assembly of 3D micro/nanostructures in advanced functional materials has important implications across broad areas of technology. Existing approaches are compatible, however, only with narrow classes of materials and/or 3D geometries. This article introduces ideas for a form of Kirigami that allows precise, mechanically driven assembly of 3D mesostructures of diverse materials from 2D micro/nanomembranes with strategically designed geometries and patterns of cuts. Theoretical and experimental studies demonstrate applicability of the methods across length scales from macro to nano, in materials ranging from monocrystalline silicon to plastic, with levels of topographical complexity that significantly exceed those that can be achieved usingmore » other approaches. A broad set of examples includes 3D silicon mesostructures and hybrid nanomembrane-nanoribbon systems, including heterogeneous combinations with polymers and metals, with critical dimensions that range from 100 nm to 30 mm. Lastly, a 3D mechanically tunable optical transmission window provides an application example of this Kirigami process, enabled by theoretically guided design.« less

Camera-based micro interferometer for distance sensing

NASA Astrophysics Data System (ADS)

Will, Matthias; Schädel, Martin; Ortlepp, Thomas

2017-12-01

Interference of light provides a high precision, non-contact and fast method for measurement method for distances. Therefore this technology dominates in high precision systems. However, in the field of compact sensors capacitive, resistive or inductive methods dominates. The reason is, that the interferometric system has to be precise adjusted and needs a high mechanical stability. As a result, we have usual high-priced complex systems not suitable in the field of compact sensors. To overcome these we developed a new concept for a very small interferometric sensing setup. We combine a miniaturized laser unit, a low cost pixel detector and machine vision routines to realize a demonstrator for a Michelson type micro interferometer. We demonstrate a low cost sensor smaller 1cm3 including all electronics and demonstrate distance sensing up to 30 cm and resolution in nm range.

Robust adhesive precision bonding in automated assembly cells

NASA Astrophysics Data System (ADS)

Müller, Tobias; Haag, Sebastian; Bastuck, Thomas; Gisler, Thomas; Moser, Hansruedi; Uusimaa, Petteri; Axt, Christoph; Brecher, Christian

2014-03-01

Diode lasers are gaining importance, making their way to higher output powers along with improved BPP. The assembly of micro-optics for diode laser systems goes along with the highest requirements regarding assembly precision. Assembly costs for micro-optics are driven by the requirements regarding alignment in a submicron and the corresponding challenges induced by adhesive bonding. For micro-optic assembly tasks a major challenge in adhesive bonding at highest precision level is the fact, that the bonding process is irreversible. Accordingly, the first bonding attempt needs to be successful. Today's UV-curing adhesives inherit shrinkage effects crucial for submicron tolerances of e.g. FACs. The impact of the shrinkage effects can be tackled by a suitable bonding area design, such as minimal adhesive gaps and an adapted shrinkage offset value for the specific assembly parameters. Compensating shrinkage effects is difficult, as the shrinkage of UV-curing adhesives is not constant between two different lots and varies even over the storage period even under ideal circumstances as first test results indicate. An up-to-date characterization of the adhesive appears necessary for maximum precision in optics assembly to reach highest output yields, minimal tolerances and ideal beamshaping results. Therefore, a measurement setup to precisely determine the up-to-date level of shrinkage has been setup. The goal is to provide necessary information on current shrinkage to the operator or assembly cell to adjust the compensation offset on a daily basis. Impacts of this information are expected to be an improved beam shaping result and a first-time-right production.

Integrated Micro/nanoengineered Functional Biomaterials for Cell Mechanics and Mechanobiology: A Materials Perspective

PubMed Central

Shao, Yue

2014-01-01

The rapid development of micro/nanoengineered functional biomaterials in the last two decades has empowered materials scientists and bioengineers to precisely control different aspects of the in vitro cell microenvironment. Following a philosophy of reductionism, many studies using synthetic functional biomaterials have revealed instructive roles of individual extracellular biophysical and biochemical cues in regulating cellular behaviors. Development of integrated micro/nanoengineered functional biomaterials to study complex and emergent biological phenomena has also thrived rapidly in recent years, revealing adaptive and integrated cellular behaviors closely relevant to human physiological and pathological conditions. Working at the interface between materials science and engineering, biology, and medicine, we are now at the beginning of a great exploration using micro/nanoengineered functional biomaterials for both fundamental biology study and clinical and biomedical applications such as regenerative medicine and drug screening. In this review, we present an overview of state of the art micro/nanoengineered functional biomaterials that can control precisely individual aspects of cell-microenvironment interactions and highlight them as well-controlled platforms for mechanistic studies of mechano-sensitive and -responsive cellular behaviors and integrative biology research. We also discuss the recent exciting trend where micro/nanoengineered biomaterials are integrated into miniaturized biological and biomimetic systems for dynamic multiparametric microenvironmental control of emergent and integrated cellular behaviors. The impact of integrated micro/nanoengineered functional biomaterials for future in vitro studies of regenerative medicine, cell biology, as well as human development and disease models are discussed. PMID:24339188

Micro-tube mass production device for microbial culture.

PubMed

Fujimoto, K; Ogawa, M; Higashi, K; Miki, N

2016-08-01

This paper describes mass production system of micro-tubes for microbial culture in an open environment. Microbes are used in many fields, such as food, medicine, environmental and energy. We proposed a microbe culture system using hydrogel micro-tubes, which can protect the target microbes inside from competitive microbes outside of the tubes while allow oxygen and nutrition to diffuse through. The hydrogel micro-tubes can be produced by a microfluidic device, which can precisely control the flow and therefore, the tube geometry. For practical applications of the micro-tube-based microbial culture, one of the biggest challenges is the scale-up of the micro-tube-based culture system, or mass production of the tubes. We developed a fluidic system that can produce multiple micro-tubes in parallel. We characterized the mass-produced micro channels and verified the effectiveness of the system.

Language Policing: Micro-Level Language Policy-in-Process in the Foreign Language Classroom

ERIC Educational Resources Information Center

Amir, Alia; Musk, Nigel

2013-01-01

This article examines what we call "micro-level language policy-in-process"--that is, how a target--language-only policy emerges "in situ" in the foreign language classroom. More precisely, we investigate the role of "language policing", the mechanism deployed by the teacher and/or pupils to (re-)establish the…

"Micro-robots" pick up a glass bead

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

2011-01-01

"Micro-robots", which are really collections of particles animated by magnetic fields, pick up a glass bead and move it around the screen. Each movement is precisely controlled. The "asters" were designed by Alexey Snezkho and Igor Aronson at Argonne National Laboratory. Video courtesy Nature Materials. Read the full story at http://go.usa.gov/KAT

Advances in Telemetry Capability as Demonstrated on an Affordable Precision Mortar

DTIC Science & Technology

2012-06-01

of high rate data and then broadcasting it over the rest of the flight test. Lastly an on-board data storage implementation using a MicroSD card is...broadcasting it over the rest of the flight test. Lastly an on- board data storage implementation using a MicroSD card is presented. KEY WORDS...the flight test. Lastly an on-board data storage implementation using a MicroSD card is presented. 2 GPS INTEGRATION Although ARL has

A new dimension in endo surgery: Micro endo surgery

PubMed Central

Pecora, Gabriele Edoardo; Pecora, Camilla Nicole

2015-01-01

There is an immense difference between tradizional Endodontic Surgery and Micro-Endo Surgery. Microsurgical techniques made possible and accessible results,that were unimaginable before. Under microscopic control,the operative techniques reached continous changes,allowing a better precision and quality standards. The dramatic evolution from Endo Surgery to Micro-Endo Surgery has enlarged the horizon of therapeutic options. Illumination and magnification through the Microscope has fundamentally and radically changed the way endo surgery can be performed. PMID:25657519

Mastering multi-depth bio-chip patterns with DVD LBRs

NASA Astrophysics Data System (ADS)

Carson, Doug

2017-08-01

Bio chip and bio disc are rapidly growing technologies used in medical, health and other industries. While there are numerous unique designs and features, these products all rely on precise three-dimensional micro-fluidic channels or arrays to move, separate and combine samples under test. These bio chip and bio disc consumables are typically manufactured by molding these parts to a precise three-dimensional pattern on a negative metal stamper, or they can be made in smaller quantities using an appropriate curable resin and a negative mold/stamper. Stampers required for bio chips have been traditionally made using either micro machining or XY stepping lithography. Both of these technologies have their advantages as well as limitations when it comes to creating micro-fluidic patterns. Significant breakthroughs in continuous maskless lithography have enabled accurate and efficient manufacturing of micro-fluidic masters using LBRs (Laser Beam Recorders) and DRIE (Deep Reactive Ion Etching). The important advantages of LBR continuous lithography vs. XY stepping lithography and micro machining are speed and cost. LBR based continuous lithography is >100x faster than XY stepping lithography and more accurate than micro machining. Several innovations were required in order to create multi-depth patterns with sub micron accuracy. By combining proven industrial LBRs with DCA's G3-VIA pattern generator and DRIE, three-dimensional bio chip masters and stampers are being manufactured efficiently and accurately.

Micro-Doppler Ambiguity Resolution for Wideband Terahertz Radar Using Intra-Pulse Interference

PubMed Central

Yang, Qi; Qin, Yuliang; Deng, Bin; Wang, Hongqiang; You, Peng

2017-01-01

Micro-Doppler, induced by micro-motion of targets, is an important characteristic of target recognition once extracted via parameter estimation methods. However, micro-Doppler is usually too significant to result in ambiguity in the terahertz band because of its relatively high carrier frequency. Thus, a micro-Doppler ambiguity resolution method for wideband terahertz radar using intra-pulse interference is proposed in this paper. The micro-Doppler can be reduced several dozen times its true value to avoid ambiguity through intra-pulse interference processing. The effectiveness of this method is proved by experiments based on a 0.22 THz wideband radar system, and its high estimation precision and excellent noise immunity are verified by Monte Carlo simulation. PMID:28468257

Micro-Doppler Ambiguity Resolution for Wideband Terahertz Radar Using Intra-Pulse Interference.

PubMed

Yang, Qi; Qin, Yuliang; Deng, Bin; Wang, Hongqiang; You, Peng

2017-04-29

Micro-Doppler, induced by micro-motion of targets, is an important characteristic of target recognition once extracted via parameter estimation methods. However, micro-Doppler is usually too significant to result in ambiguity in the terahertz band because of its relatively high carrier frequency. Thus, a micro-Doppler ambiguity resolution method for wideband terahertz radar using intra-pulse interference is proposed in this paper. The micro-Doppler can be reduced several dozen times its true value to avoid ambiguity through intra-pulse interference processing. The effectiveness of this method is proved by experiments based on a 0.22 THz wideband radar system, and its high estimation precision and excellent noise immunity are verified by Monte Carlo simulation.

Fixed-Wing Micro Aerial Vehicle for Accurate Corridor Mapping

NASA Astrophysics Data System (ADS)

Rehak, M.; Skaloud, J.

2015-08-01

In this study we present a Micro Aerial Vehicle (MAV) equipped with precise position and attitude sensors that together with a pre-calibrated camera enables accurate corridor mapping. The design of the platform is based on widely available model components to which we integrate an open-source autopilot, customized mass-market camera and navigation sensors. We adapt the concepts of system calibration from larger mapping platforms to MAV and evaluate them practically for their achievable accuracy. We present case studies for accurate mapping without ground control points: first for a block configuration, later for a narrow corridor. We evaluate the mapping accuracy with respect to checkpoints and digital terrain model. We show that while it is possible to achieve pixel (3-5 cm) mapping accuracy in both cases, precise aerial position control is sufficient for block configuration, the precise position and attitude control is required for corridor mapping.

The optional selection of micro-motion feature based on Support Vector Machine

NASA Astrophysics Data System (ADS)

Li, Bo; Ren, Hongmei; Xiao, Zhi-he; Sheng, Jing

2017-11-01

Micro-motion form of target is multiple, different micro-motion forms are apt to be modulated, which makes it difficult for feature extraction and recognition. Aiming at feature extraction of cone-shaped objects with different micro-motion forms, this paper proposes the best selection method of micro-motion feature based on support vector machine. After the time-frequency distribution of radar echoes, comparing the time-frequency spectrum of objects with different micro-motion forms, features are extracted based on the differences between the instantaneous frequency variations of different micro-motions. According to the methods based on SVM (Support Vector Machine) features are extracted, then the best features are acquired. Finally, the result shows the method proposed in this paper is feasible under the test condition of certain signal-to-noise ratio(SNR).

Micro/Nanoscale Parallel Patterning of Functional Biomolecules, Organic Fluorophores and Colloidal Nanocrystals

PubMed Central

2009-01-01

We describe the design and optimization of a reliable strategy that combines self-assembly and lithographic techniques, leading to very precise micro-/nanopositioning of biomolecules for the realization of micro- and nanoarrays of functional DNA and antibodies. Moreover, based on the covalent immobilization of stable and versatile SAMs of programmable chemical reactivity, this approach constitutes a general platform for the parallel site-specific deposition of a wide range of molecules such as organic fluorophores and water-soluble colloidal nanocrystals. PMID:20596482

VIEW OF MICROMACHINING, HIGH PRECISION EQUIPMENT USED TO CUSTOM MAKE ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

VIEW OF MICRO-MACHINING, HIGH PRECISION EQUIPMENT USED TO CUSTOM MAKE SMALL PARTS. LUMPS OF CLAY; SHOWN IN THE PHOTOGRAPH, WERE USED TO STABILIZE PARTS BEING MACHINED. (11/1/87) - Rocky Flats Plant, Stainless Steel & Non-Nuclear Components Manufacturing, Southeast corner of intersection of Cottonwood & Third Avenues, Golden, Jefferson County, CO

A novel technique for micro-hole forming on skull with the assistance of ultrasonic vibration.

PubMed

Li, Zhe; Yang, Daoguo; Hao, Weidong; Wu, Tiecheng; Wu, Song; Li, Xiaoping

2016-04-01

Micro-hole opening on skull is technically challenging and is hard to realize by micro-drilling. Low-stiffness of the drill bit is a serious drawback in micro-drilling. To deal with this problem, a novel ultrasonic vibration assisted micro-hole forming technique has been developed. Tip geometry and vibration amplitude are two key factors affecting the performance of this hole forming technique. To investigate their effects, experiment was carried out with 300μm diameter tools of three different tip geometries at three different vibration amplitudes. Hole forming performance was evaluated by the required thrust force, dimensional accuracy, exit burr and micro-structure of bone tissue around the generated hole. Based on the findings from current study, the 60° conically tipped tool helps generate a micro-hole of better quality at a smaller thrust force, and it is more suitable for hole forming than the 120° conically tipped tool and the blunt tipped tool. As for the vibration amplitude, when a larger amplitude is used, a micro-hole of better quality and higher dimensional accuracy can be formed at a smaller thrust force. Findings from this study would lay a technical foundation for accurately generating a high-quality micro-hole on skull, which enables minimally invasive insertion of a microelectrode into brain for neural activity measuring. Copyright © 2015 Elsevier Ltd. All rights reserved.

Controlled drive-in and precipitation of hydrogen during plasma hydrogenation of silicon using a thin compressively strained SiGe layer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Okba, F.; Departement Optique et Mecanique de Precision, Faculte des Sciences de l'Ingenieur, Universite Ferhat Abbas, Setif 19000; Cherkashin, N.

2010-07-19

We have quantitatively studied by transmission electron microscopy the growth kinetics of platelets formed during the continuous hydrogenation of a Si substrate/SiGe/Si heterostructure. We have evidenced and explained the massive transfer of hydrogen from a population of platelets initially generated in the upper Si layer by plasma hydrogenation towards a population of larger platelets located in the SiGe layer. We demonstrate that this type of process can be used not only to precisely localize the micro-cracks, then the fracture line at a given depth but also to 'clean' the top layer from pre-existing defects.

System identification of the JPL micro-precision interferometer truss - Test-analysis reconciliation

NASA Technical Reports Server (NTRS)

Red-Horse, J. R.; Marek, E. L.; Levine-West, M.

1993-01-01

The JPL Micro-Precision Interferometer (MPI) is a testbed for studying the use of control-structure interaction technology in the design of space-based interferometers. A layered control architecture will be employed to regulate the interferometer optical system to tolerances in the nanometer range. An important aspect of designing and implementing the control schemes for such a system is the need for high fidelity, test-verified analytical structural models. This paper focuses on one aspect of the effort to produce such a model for the MPI structure, test-analysis model reconciliation. Pretest analysis, modal testing, and model refinement results are summarized for a series of tests at both the component and full system levels.

Integrated micro/nanoengineered functional biomaterials for cell mechanics and mechanobiology: a materials perspective.

PubMed

Shao, Yue; Fu, Jianping

2014-03-12

The rapid development of micro/nanoengineered functional biomaterials in the last two decades has empowered materials scientists and bioengineers to precisely control different aspects of the in vitro cell microenvironment. Following a philosophy of reductionism, many studies using synthetic functional biomaterials have revealed instructive roles of individual extracellular biophysical and biochemical cues in regulating cellular behaviors. Development of integrated micro/nanoengineered functional biomaterials to study complex and emergent biological phenomena has also thrived rapidly in recent years, revealing adaptive and integrated cellular behaviors closely relevant to human physiological and pathological conditions. Working at the interface between materials science and engineering, biology, and medicine, we are now at the beginning of a great exploration using micro/nanoengineered functional biomaterials for both fundamental biology study and clinical and biomedical applications such as regenerative medicine and drug screening. In this review, an overview of state of the art micro/nanoengineered functional biomaterials that can control precisely individual aspects of cell-microenvironment interactions is presented and they are highlighted them as well-controlled platforms for mechanistic studies of mechano-sensitive and -responsive cellular behaviors and integrative biology research. The recent exciting trend where micro/nanoengineered biomaterials are integrated into miniaturized biological and biomimetic systems for dynamic multiparametric microenvironmental control of emergent and integrated cellular behaviors is also discussed. The impact of integrated micro/nanoengineered functional biomaterials for future in vitro studies of regenerative medicine, cell biology, as well as human development and disease models are discussed. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

[Application and outlook of three-dimensional printing in prosthetic dentistry].

PubMed

Sun, Y C; Li, R; Zhou, Y S; Wang, Y

2017-06-09

At present, three-dimensional (3D) printing has been applied in many aspects in the field of prosthodontics, such as dental models, wax patterns, guide plates, dental restoration and customized implants. The common forming principles include light curing, sintering and melting-condensation, the materials include pure wax, resin, metal and ceramics. However, the printing precision and the strength of multi-material integrated forming, remains to be improved. In addition, as a technology by which the internal structure of a material can be customized manufacturing, further advantage of 3D printing used in the manufacture of dental restoration lies in the customization functional bionic micro-structures, but the related research is still in its infancy. The review briefly summarizes the commonly used 3D printing crafts in prosthetic dentistry, and details clinical applications and evaluations, provides references for clinical decision and further research.

Linear State-Space Representation of the Dynamics of Relative Motion, Based on Restricted Three Body Dynamics

NASA Technical Reports Server (NTRS)

Luquette,Richard J.; Sanner, Robert M.

2004-01-01

Precision Formation Flying is an enabling technology for a variety of proposed space-based observatories, including the Micro-Arcsecond X-ray Imaging Mission (MAXIM) , the associated MAXIM pathfinder mission, Stellar Imager (SI) and the Terrestrial Planet Finder (TPF). An essential element of the technology is the control algorithm, requiring a clear understanding of the dynamics of relative motion. This paper examines the dynamics of relative motion in the context of the Restricted Three Body Problem (RTBP). The natural dynamics of relative motion are presented in their full nonlinear form. Motivated by the desire to apply linear control methods, the dynamics equations are linearized and presented in state-space form. The stability properties are explored for regions in proximity to each of the libration points in the Earth/Moon - Sun rotating frame. The dynamics of relative motion are presented in both the inertial and rotating coordinate frames.

Avian reovirus microNS protein forms homo-oligomeric inclusions in a microtubule-independent fashion, which involves specific regions of its C-terminal domain.

PubMed

Brandariz-Nuñez, Alberto; Menaya-Vargas, Rebeca; Benavente, Javier; Martinez-Costas, Jose

2010-05-01

Members of the genus Orthoreovirus replicate in cytoplasmic inclusions termed viral factories. Compelling evidence suggests that the nonstructural protein microNS forms the matrix of the factories and recruits specific viral proteins to these structures. In the first part of this study, we analyzed the properties of avian reovirus factories and microNS-derived inclusions and found that they are nonaggresome cytoplasmic globular structures not associated with the cytoskeleton which do not require an intact microtubule network for formation and maturation. We next investigated the capacity of avian reovirus microNS to form inclusions in transfected and baculovirus-infected cells. Our results showed that microNS is the main component of the inclusions formed by recombinant baculovirus expression. This, and the fact that microNS is able to self-associate inside the cell, suggests that microNS monomers contain all the interacting domains required for inclusion formation. Examination of the inclusion-forming capacities of truncated microNS versions allowed us to identify the region spanning residues 448 to 635 of microNS as the smallest that was inclusion competent, although residues within the region 140 to 380 seem to be involved in inclusion maturation. Finally, we investigated the roles that four different motifs present in microNS(448-635) play in inclusion formation, and the results suggest that the C-terminal tail domain is a key determinant in dictating the initial orientation of monomer-to-monomer contacts to form basal oligomers that control inclusion shape and inclusion-forming efficiency. Our results contribute to an understanding of the generation of structured protein aggregates that escape the cellular mechanisms of protein recycling.

Mobile System for Precise Aero Delivery with Global Reach Network Capability

DTIC Science & Technology

2009-08-30

No intention / need for taking advantage of networking with other agents. The Atair’s Onyx Micro Light ( Onyx ML) delivery system (www.atair.com... onyx ) (Fig.9a) is a precision airdrop system designed to address the requirements of the Joint Precision Airdrop System MLW (JPADS-MLW) system of the...autonomous powered paraglider (LEAPP) developed under contract with DARPA (Fig.9b). a) b) Fig. 9. Onyx ML with mock sensor payload release

Application of a microplate-based ORAC-pyrogallol red assay for the estimation ofantioxidant capacity: First Action 2012.03.

PubMed

Ortiz, Rocío; Antilén, Mónica; Speisky, Hernán; Aliaga, Margarita E; López-Alarcón, Camilo; Baugh, Steve

2012-01-01

A method was developed for microplate-based oxygen radicals absorbance capacity (ORAC) using pyrogallol red (PGR) as probe (ORAC-PGR). The method was evaluated for linearity, precision, and accuracy. In addition, the antioxidant capacity of commercial beverages, such as wines, fruit juices, and iced teas, was measured. Linearity of the area under the curve (AUC) versus Trolox concentration plots was [AUC = (845 +/- 110) + (23 +/- 2) [Trolox, microM]; R = 0.9961, n = 19]. Analyses showed better precision and accuracy at the highest Trolox concentration (40 microM) with RSD and recovery (REC) values of 1.7 and 101.0%, respectively. The method also showed good linearity for red wine [AUC = (787 +/- 77) + (690 +/- 60) [red wine, microL/mL]; R = 0.9926, n = 17], precision and accuracy with RSD values from 1.4 to 8.3%, and REC values that ranged from 89.7 to 103.8%. Red wines showed higher ORAC-PGR values than white wines, while the ORAC-PGR index of fruit juices and iced teas presented a wide range of results, from 0.6 to 21.6 mM of Trolox equivalents. Product-to-product variability was also observed for juices of the same fruit, showing the differences between brands on the ORAC-PGR index.

Micro Machining of Injection Mold Inserts for Fluidic Channel of Polymeric Biochips

PubMed Central

Jung, Woo-Chul; Heo, Young-Moo; Yoon, Gil-Sang; Shin, Kwang-Ho; Chang, Sung-Ho; Kim, Gun-Hee; Cho, Myeong-Woo

2007-01-01

Recently, the polymeric micro-fluidic biochip, often called LOC (lab-on-a-chip), has been focused as a cheap, rapid and simplified method to replace the existing biochemical laboratory works. It becomes possible to form miniaturized lab functionalities on a chip with the development of MEMS technologies. The micro-fluidic chips contain many micro-channels for the flow of sample and reagents, mixing, and detection tasks. Typical substrate materials for the chip are glass and polymers. Typical techniques for microfluidic chip fabrication are utilizing various micro pattern forming methods, such as wet-etching, micro-contact printing, and hot-embossing, micro injection molding, LIGA, and micro powder blasting processes, etc. In this study, to establish the basis of the micro pattern fabrication and mass production of polymeric micro-fluidic chips using injection molding process, micro machining method was applied to form micro-channels on the LOC molds. In the research, a series of machining experiments using micro end-mills were performed to determine optimum machining conditions to improve surface roughness and shape accuracy of designed simplified micro-channels. Obtained conditions were used to machine required mold inserts for micro-channels using micro end-mills. Test injection processes using machined molds and COC polymer were performed, and then the results were investigated.

Design of the micro pressure multi-node measuring system for micro-fluidic chip

NASA Astrophysics Data System (ADS)

Mu, Lili; Guo, Shuheng; Rong, Li; Yin, Ke

2016-01-01

An online multi-node microfludic pressure measuring system was designed in the paper. The research focused on the design of pressure test circuit system and methods on dealing with pressure data collecting. The MPXV7002 micro-pressure sensor was selected to measure the chip inside channel pressure and installed by a silicone tube on different micro-channel measured nodes. The pressure transmission loss was estimated in the paper, and corrected by the filtering and smoothing method. The pressure test experiment was carried out and the data were analyzed. Finally, the measuring system was calibrated. The results showed that the measuring system had high testing precision.

Influence of different light intensities on the content of diosgenin, lipids, carotenoids and fatty acids in leaves of Dioscorea zingiberensis.

PubMed

Li, Huming; Radunz, Alfons; He, Ping; Schmid, Georg H

2002-01-01

Cultivation of the climbing plant Dioscorea zingiberensis at a light intensity of 100 microE. m(-2) sec(-1) yields three different phenotypes. Most of the plants grow as green phenotype (DzW). Two further forms differ in their leaf shape and leaf color. Whereas one type exhibits a more pointed leaf shape in the upper part of the plant with leaves appearing yellow-green with white stripes or hatchings (DzY), the other type shows a more round leaf shape with an intensive yellow-green color (DzT). These three plant types differ in their diosgenin content not only in their rhizomes but also in the chloroplasts. In the rhizomes the diosgenin content in the green form is 0.4%, in the DzY-form 0.6% and in the DzT-form even 1.3% of the dry weight. Furthermore, even in chloroplasts of the green DzW-form and of the DzY-form the presence of diosgenin was demonstrated. It occurs there as the epimeric form yamogenin. The DzT-form contains no yamogenin in its chloroplasts. Besides this, these plant forms differ in their chlorophyll and carotenoid content and in their fatty acid composition. Carotenoids increase from 1.3% of total lipids in the green phenotype to 3.3% in the DzY- and to 4.2% in the DzT-form. This increase refers to beta-carotene as well as to lutein and neoxanthin. The chlorophyll content in the green type is 8.1% and lower in the DzY-form with 7%. The highest chlorophyll content is found in the DzT-form with 12%. Fatty acids in the DzY-form and in the DzT-form have a more unsaturated character than in the green phenotype. The content of the monoenoic acid trans-hexadecenoic acid is considerably lower in both phenotypes when compared to the green phenotype. In both phenotypes the quantity of fatty acids with 16 carbon atoms is reduced, whereas fatty acids with 18 carbon atoms occur in higher concentration. Cultivation of the green phenotype (DzW) at the three light intensities of 10, 100 and 270 microE x m(-2) x sec(-1) leads to changes of the diosgenin content in rhizomes, to an increase of leaf dry weight, to a reduction of the grana structure in chloroplasts and therewith to a decrease of the chlorophyll content. The total lipid content is highest under the cultivation at 100 microE x m(-2) x sec(-1) and reduced by 30% at 10 and 270 microE x m(-2) x sec(-1). Carotenoids, however, are highest in shaded plants (10 microE x m(-2) x sec(-1)) and plants grown under high light conditions of 270 microE x m(-2) x sec(-1). At 100 microE x m(-2) x sec(-1) a decrease of saturated fatty acids is observed in comparison to plants grown under shaded conditions.

Coherent Synchrotron-Based Micro-Imaging Employed for Studies of Micro-Gap Formation in Dental Implants

NASA Astrophysics Data System (ADS)

Rack, T.; Zabler, S.; Rack, A.; Stiller, M.; Riesemeier, H.; Cecilia, A.; Nelson, K.

2011-09-01

Biocompatible materials such as titanium are regularly applied in oral surgery. Titanium-based implants for the replacement of missing teeth demand a high mechanical precision in order to minimize micro-bacterial leakage, especially when two-piece concepts are used. Synchrotron-based hard x-ray radiography, unlike conventional laboratory radiography, allows high spatial resolution in combination with high contrast even when micro-sized features in such highly attenuating objects are visualized. Therefore, micro-gap formation at interfaces in two-piece dental implants with the sample under different mechanical loads can be studied. We show the existence of micro-gaps in implants with conical connections and study the mechanical behavior of the mating zone of conical implants during loading. The micro-gap is a potential source of implant failure, i.e., bacterial leakage, which can be a stimulus for an inflammatory process.

Coherent Synchrotron-Based Micro-Imaging Employed for Studies of Micro-Gap Formation in Dental Implants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rack, T.; Stiller, M.; Nelson, K.

Biocompatible materials such as titanium are regularly applied in oral surgery. Titanium-based implants for the replacement of missing teeth demand a high mechanical precision in order to minimize micro-bacterial leakage, especially when two-piece concepts are used. Synchrotron-based hard x-ray radiography, unlike conventional laboratory radiography, allows high spatial resolution in combination with high contrast even when micro-sized features in such highly attenuating objects are visualized. Therefore, micro-gap formation at interfaces in two-piece dental implants with the sample under different mechanical loads can be studied. We show the existence of micro-gaps in implants with conical connections and study the mechanical behavior ofmore » the mating zone of conical implants during loading. The micro-gap is a potential source of implant failure, i.e., bacterial leakage, which can be a stimulus for an inflammatory process.« less

MicroRNA function in Drosophila melanogaster.

PubMed

Carthew, Richard W; Agbu, Pamela; Giri, Ritika

2017-05-01

Over the last decade, microRNAs have emerged as critical regulators in the expression and function of animal genomes. This review article discusses the relationship between microRNA-mediated regulation and the biology of the fruit fly Drosophila melanogaster. We focus on the roles that microRNAs play in tissue growth, germ cell development, hormone action, and the development and activity of the central nervous system. We also discuss the ways in which microRNAs affect robustness. Many gene regulatory networks are robust; they are relatively insensitive to the precise values of reaction constants and concentrations of molecules acting within the networks. MicroRNAs involved in robustness appear to be nonessential under uniform conditions used in conventional laboratory experiments. However, the robust functions of microRNAs can be revealed when environmental or genetic variation otherwise has an impact on developmental outcomes. Copyright © 2016 Elsevier Ltd. All rights reserved.

Fabrication of micro/nano optical fiber by mechano-electrospinning

NASA Astrophysics Data System (ADS)

Chen, Qinnan; Wu, Dezhi; Yu, Zhe; Mei, Xuecui; Fang, Ke; Sun, Daoheng

2017-10-01

We study a novel fabrication method of micro/nano optical fiber by mechano-electrospinning (MES) direct-written technology. MES process is able to precisely manipulate the position and diameter of the electro-spun micro/nano fiber by adjusting the mechanical drawing force, which through changing the speed of motion stage (substrate). By adjusting the substrate speed, the nozzle-to-substrate distance and the applied voltage, the poly(methyl methacrylate) (PMMA) micro/nano optical fibers (MNOF) with controlled diameter are obtained and the tapered MNOF are fabricated by continuously changing the substrate speed. The transmission characteristics of PMMA micro/nano fiber is experimentally demonstrated, and a PMMA micro/nano fiber based refractive index sensor is designed. Our works shows the new fabrication method of MNOF by MES has the potential in the field of light mode conversion, optical waveguide coupling, refractive index detection and new micro/nano optical fiber components.

CANYVAL-X: Enabling a new class of scientific instruments

NASA Astrophysics Data System (ADS)

Shah, Neerav; Calhoun, Philip C.; Park, Sang-young; Keidar, Michael

2016-05-01

Significant new discoveries in space science can be realized by replacing the traditional large monolithic space telescopes with precision formation flying spacecraft to form a “virtual telescope.” Such virtual telescopes will revolutionize occulting imaging systems, provide images of the Sun, accretion disks, and other astronomical objects with unprecedented milli-arcsecond resolution (several orders of magnitude beyond current capability).Since the days of Apollo, NASA and other organizations have been conducting formation flying in space, but not with the precision required for virtual telescopes. These efforts have focused on rendezvous and docking (e.g., crew docking, satellite servicing, etc.) and/or ground-controlled coordinated flight (e.g., EO-1, GRAIL, MMS, etc.). While the TRL of the component level technology for formation flying is high, the capability for the system-level guidance, navigation, and control (GN&C) technology required to align a virtual telescope to an inertial astronomical target with sub-arcsecond precision is not fully developed.The CANYVAL-X (CubeSat Astronomy by NASA and Yonsei using Virtual Telescope Alignment eXperiment) mission is an engineering proof of concept featuring a pair of CubeSats flying as a tandem telescope with a goal of demonstrating the system-level GN&C needed to form a virtual telescope. NASA partnered with the George Washington University and the Yonsei University to design and develop CANYVAL-X. CANYVAL-X will demonstrate key technologies for using virtual telescopes in space, including micro-propulsion using millinewton thrusters, relative position sensing, and communications control between the two spacecraft. CANYVAL-X is scheduled to launch on a Flacon-9 in summer of 2016.

Experimental Characterization of Hysteresis in a Revolute Joint for Precision Deployable Structures

NASA Technical Reports Server (NTRS)

Lake, Mark S.; Fung, Jimmy; Gloss, Kevin; Liechty, Derek S.

1997-01-01

Recent studies of the micro-dynamic behavior of a deployable telescope metering truss have identified instabilities in the equilibrium shape of the truss in response to low-energy dynamic loading. Analyses indicate that these micro-dynamic instabilities arise from stick-slip friction within the truss joints (e.g., hinges and latches). The present study characterizes the low-magnitude quasi-static load cycle response of the precision revolute joints incorporated in the deployable telescope metering truss, and specifically, the hysteretic response of these joints caused by stick-slip friction within the joint. Detailed descriptions are presented of the test setup and data reduction algorithms, including discussions of data-error sources and data-filtering techniques. Test results are presented from thirteen specimens, and the effects of joint preload and manufacturing tolerances are investigated. Using a simplified model of stick-slip friction, a relationship is made between joint load-cycle behavior and micro-dynamic dimensional instabilities in the deployable telescope metering truss.

Microstructural Evolution at Micro/Meso-Scale in an Ultrafine-Grained Pure Aluminum Processed by Equal-Channel Angular Pressing with Subsequent Annealing Treatment.

PubMed

Xu, Jie; Li, Jianwei; Zhu, Xiaocheng; Fan, Guohua; Shan, Debin; Guo, Bin

2015-11-04

Micro-forming with ultrafine-grained (UFG) materials is a promising direction for the fabrication of micro-electro-mechanical systems (MEMS) components due to the improved formability, good surface quality, and excellent mechanical properties it provides. In this paper, micro-compression tests were performed using UFG pure aluminum processed by equal-channel angular pressing (ECAP) with subsequent annealing treatment. Microstructural evolution was investigated by electron back-scattered diffraction (EBSD) and transmission electron microscopy (TEM). The results show that microstructural evolutions during compression tests at the micro/meso-scale in UFG pure Al are absolutely different from the coarse-grained (CG) materials. A lot of low-angle grain boundaries (LAGBs) and recrystallized fine grains are formed inside of the original large grains in CG pure aluminum after micro-compression. By contrast, ultrafine grains are kept with few sub-grain boundaries inside the grains in UFG pure aluminum, which are similar to the original microstructure before micro-compression. The surface roughness and coordinated deformation ability can be signmicrostructure; micro/meso-forming; ultrafine grains; ECAP; aluminumificantly improved with UFG pure aluminum, which demonstrates that the UFG materials have a strong potential application in micro/meso-forming.

The study about forming high-precision optical lens minimalized sinuous error structures for designed surface

NASA Astrophysics Data System (ADS)

Katahira, Yu; Fukuta, Masahiko; Katsuki, Masahide; Momochi, Takeshi; Yamamoto, Yoshihiro

2016-09-01

Recently, it has been required to improve qualities of aspherical lenses mounted on camera units. Optical lenses in highvolume production generally are applied with molding process using cemented carbide or Ni-P coated steel, which can be selected from lens material such as glass and plastic. Additionally it can be obtained high quality of the cut or ground surface on mold due to developments of different mold product technologies. As results, it can be less than 100nmPV as form-error and 1nmRa as surface roughness in molds. Furthermore it comes to need higher quality, not only formerror( PV) and surface roughness(Ra) but also other surface characteristics. For instance, it can be caused distorted shapes at imaging by middle spatial frequency undulations on the lens surface. In this study, we made focus on several types of sinuous structures, which can be classified into form errors for designed surface and deteriorate optical system performances. And it was obtained mold product processes minimalizing undulations on the surface. In the report, it was mentioned about the analyzing process by using PSD so as to evaluate micro undulations on the machined surface quantitatively. In addition, it was mentioned that the grinding process with circumferential velocity control was effective for large aperture lenses fabrication and could minimalize undulations appeared on outer area of the machined surface, and mentioned about the optical glass lens molding process by using the high precision press machine.

Using micro-patterned surfaces to inhibit settlement and biofilm formation by Bacillus subtilis.

PubMed

Chang, Siyuan; Chen, Xiaodong; Jiang, Shuo; Chen, Jinchun; Shi, Lin

2017-07-01

Biofilm is a biological complex caused by bacteria attachment to the substrates and their subsequent reproduction and secretion. This phenomenon reduces heat transfer efficiency and causes significant losses in treated sewage heat-recovering systems. This paper describes a physical approach to inhibit bacteria settlement and biofilm formation by Bacillus subtilis, which is the dominant species in treated sewage. Here, micro-patterned surfaces with different characteristics (stripe and cube) and dimensions (1-100 μm) were fabricated as surfaces of interest. Model sewage was prepared and a rotating coupon device was used to form the biofilms. Precision balance, scanning electron microscopy, and confocal laser scanning microscopy (CLSM) were employed to investigate the inhibitory effects and the mechanisms of the biofilm-surface interactions. The results have shown that surfaces with small pattern sizes (1 and 2 μm) all reduced biofilm formation significantly. Interestingly, the CLSM images showed that the surfaces do not play a role in "killing" the bacteria. These findings are useful for future development of new process surfaces on which bacteria settlement and biofilm formation can be inhibited or minimized.

Microfabrication technology by femtosecond laser direct scanning using two-photon photo-polymerization

NASA Astrophysics Data System (ADS)

Zhou, Ming; Liu, Li-Peng; Dai, Qi-Xun; Pan, Chuan-Peng

2005-01-01

Two-photon absorption (TPA) is confined at the focus under tight-focusing conditions, which provides a novel concept for micro-fabrication using two-photon photo-polymerization in resin. The development of three-dimensional micro-fabrication by femtosecond laser was introduced at first, then the merits of femtosecond two-photon photo-polymerization was expatiated. Femtosecond laser direct scanning three-dimensional (3D) micro-fabrication system was set up and corresponding controlling software was developed. We demonstrated a fabrication of three-dimensional microstructures using photo-polymerization of resin by two-photon absorption. The precision of micro-machining and the spatial resolution reached 1um because of TPA. The dependence of fabricated line width to the micro-fabrication speed was investigated. Benzene ring, CHINA and layer-by-layer of log structures were fabricated in this 3D- micro-fabrication system as examples.

Dewetting Based Fabrication of Fibrous Micro-Scaffolds as Potential Injectable Cell Carriers

PubMed Central

Song, Hokyung; Yin, Liya; Chilian, William M.; Newby, Bi-min Zhang

2014-01-01

Although regenerative medicine utilizing tissue scaffolds has made enormous strides in recent years, many constraints still hamper their effectiveness. A limitation of many scaffolds is that they form surface patches, which are not particularly effective for some types of “wounds” that are deep within tissues, e.g., stroke, myocardial infarction. In this study, we reported the generation of fibrous micro-scaffolds feasible for delivering cells by injection into the tissue parenchyma. The micro-scaffolds (widths < 100 μm) were made by dewetting of poly (lactic-coglycolic acid) thin films containing parallel strips, and cells were seeded to form cell/polymer micro-constructs during or post the micro-scaffold fabrication process. Five types of cells including rat induced vascular progenitor cells were assessed for the formation of the micro-constructs. Critical factors in forming fibrous micro-scaffolds via dewetting of polymer thin films were found to be properties of polymers and supporting substrates, temperature, and proteins in the culture medium. Also, the ability of cells to attach to the micro-scaffolds was essential for forming cell/polymer micro-constructs. Both in vitro and in vivo assessments of injecting these micro-scaffolding constructs showed, as compared to free cells, enhanced cell retention at the injected site, which could lead to improved tissue engineering and regeneration. PMID:25579969

MicroRNAs form triplexes with double stranded DNA at sequence-specific binding sites; a eukaryotic mechanism via which microRNAs could directly alter gene expression

DOE PAGES

Paugh, Steven W.; Coss, David R.; Bao, Ju; ...

2016-02-04

MicroRNAs are important regulators of gene expression, acting primarily by binding to sequence-specific locations on already transcribed messenger RNAs (mRNA). Recent studies indicate that microRNAs may also play a role in up-regulating mRNA transcription levels, although a definitive mechanism has not been established. Double-helical DNA is capable of forming triple-helical structures through Hoogsteen and reverse Hoogsteen interactions in the major groove of the duplex, and we show physical evidence that microRNAs form triple-helical structures with duplex DNA, and identify microRNA sequences that favor triplex formation. We developed an algorithm (Trident) to search genome-wide for potential triplex-forming sites and show thatmore » several mammalian and non-mammalian genomes are enriched for strong microRNA triplex binding sites. We show that those genes containing sequences favoring microRNA triplex formation are markedly enriched (3.3 fold, p<2.2 x 10 -16) for genes whose expression is positively correlated with expression of microRNAs targeting triplex binding sequences. As a result, this work has thus revealed a new mechanism by which microRNAs can interact with gene promoter regions to modify gene transcription.« less

MicroRNAs form triplexes with double stranded DNA at sequence-specific binding sites; a eukaryotic mechanism via which microRNAs could directly alter gene expression

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paugh, Steven W.; Coss, David R.; Bao, Ju

MicroRNAs are important regulators of gene expression, acting primarily by binding to sequence-specific locations on already transcribed messenger RNAs (mRNA). Recent studies indicate that microRNAs may also play a role in up-regulating mRNA transcription levels, although a definitive mechanism has not been established. Double-helical DNA is capable of forming triple-helical structures through Hoogsteen and reverse Hoogsteen interactions in the major groove of the duplex, and we show physical evidence that microRNAs form triple-helical structures with duplex DNA, and identify microRNA sequences that favor triplex formation. We developed an algorithm (Trident) to search genome-wide for potential triplex-forming sites and show thatmore » several mammalian and non-mammalian genomes are enriched for strong microRNA triplex binding sites. We show that those genes containing sequences favoring microRNA triplex formation are markedly enriched (3.3 fold, p<2.2 x 10 -16) for genes whose expression is positively correlated with expression of microRNAs targeting triplex binding sequences. As a result, this work has thus revealed a new mechanism by which microRNAs can interact with gene promoter regions to modify gene transcription.« less

Quadrilateral Micro-Hole Array Machining on Invar Thin Film: Wet Etching and Electrochemical Fusion Machining

PubMed Central

Choi, Woong-Kirl; Kim, Seong-Hyun; Choi, Seung-Geon; Lee, Eun-Sang

2018-01-01

Ultra-precision products which contain a micro-hole array have recently shown remarkable demand growth in many fields, especially in the semiconductor and display industries. Photoresist etching and electrochemical machining are widely known as precision methods for machining micro-holes with no residual stress and lower surface roughness on the fabricated products. The Invar shadow masks used for organic light-emitting diodes (OLEDs) contain numerous micro-holes and are currently machined by a photoresist etching method. However, this method has several problems, such as uncontrollable hole machining accuracy, non-etched areas, and overcutting. To solve these problems, a machining method that combines photoresist etching and electrochemical machining can be applied. In this study, negative photoresist with a quadrilateral hole array pattern was dry coated onto 30-µm-thick Invar thin film, and then exposure and development were carried out. After that, photoresist single-side wet etching and a fusion method of wet etching-electrochemical machining were used to machine micro-holes on the Invar. The hole machining geometry, surface quality, and overcutting characteristics of the methods were studied. Wet etching and electrochemical fusion machining can improve the accuracy and surface quality. The overcutting phenomenon can also be controlled by the fusion machining. Experimental results show that the proposed method is promising for the fabrication of Invar film shadow masks. PMID:29351235

A micromachined piezoelectric microgripper for manipulation of micro/nanomaterials

NASA Astrophysics Data System (ADS)

Shi, Huaduo; Shi, Weiliang; Zhang, Ran; Zhai, Junyi; Chu, Jinkui; Dong, Shuxiang

2017-06-01

Micro/nanomaterials and devices have attracted great interest in recent years because of their extensive application prospects in almost all kinds of fields. However, the manipulations of the material at the micro/nanoscale, such as the separation or transfer of a micro/nano-object in the process of assembling micro/nanodevices, are quite difficult. In this paper, we present a micromachined micro-gripper made of photoresist material (SU-8) and driven by piezoelectric Pb(Mg,Nb)O3-PbTiO3 single crystal pieces. In order to keep two grasping jaws of the micro-gripper operating in the same plane at the micro/nanometer scale, a fine circular flexure hinge was fabricated for elastically connecting them together. After introducing the interface effect, the relationship between the opening stroke of two jaws and the applied voltage was developed and then confirmed by finite element simulation. The micro-gripper was finally installed on a six degree of freedom stage for performing a pick-up, release, and transfer manipulation of a 2 μm ZnO micro-fiber. The presented piezoelectric micro-gripper shows a great potential for the precise manipulation of a single piece of micro/nanomaterial for micro/nanodevices' assembling.

A three dimensional scaffold with precise micro-architecture and surface micro-textures

PubMed Central

Mata, Alvaro; Kim, Eun Jung; Boehm, Cynthia A.; Fleischman, Aaron J.; Muschler, George F.; Roy, Shuvo

2013-01-01

A three-dimensional (3D) structure comprising precisely defined microarchitecture and surface micro-textures, designed to present specific physical cues to cells and tissues, may provide an efficient scaffold in a variety of tissue engineering and regenerative medicine applications. We report a fabrication technique based on microfabrication and soft lithography that permits for the development of 3D scaffolds with both precisely engineered architecture and tailored surface topography. The scaffold fabrication technique consists of three key steps starting with microfabrication of a mold using an epoxy-based photoresist (SU-8), followed by dual-sided molding of a single layer of polydimethylsiloxane (PDMS) using a mechanical jig for precise motion control; and finally, alignment, stacking, and adhesion of multiple PDMS layers to achieve a 3D structure. This technique was used to produce 3D Texture and 3D Smooth PDMS scaffolds, where the surface topography comprised 10 μm-diameter/height posts and smooth surfaces, respectively. The potential utility of the 3D microfabricated scaffolds, and the role of surface topography, were subsequently investigated in vitro with a combined heterogeneous population of adult human stem cells and their resultant progenitor cells, collectively termed connective tissue progenitors (CTPs), under conditions promoting the osteoblastic phenotype. Examination of bone-marrow derived CTPs cultured on the 3D Texture scaffold for 9 days revealed cell growth in three dimensions and increased cell numbers compared to those on the 3D Smooth scaffold. Furthermore, expression of alkaline phosphatase mRNA was higher on the 3D Texture scaffold, while osteocalcin mRNA expression was comparable for both types of scaffolds. PMID:19524292

Micro-costing studies in the health and medical literature: protocol for a systematic review

PubMed Central

2014-01-01

Background Micro-costing is a cost estimation method that allows for precise assessment of the economic costs of health interventions. It has been demonstrated to be particularly useful for estimating the costs of new interventions, for interventions with large variability across providers, and for estimating the true costs to the health system and to society. However, existing guidelines for economic evaluations do not provide sufficient detail of the methods and techniques to use when conducting micro-costing analyses. Therefore, the purpose of this study is to review the current literature on micro-costing studies of health and medical interventions, strategies, and programs to assess the variation in micro-costing methodology and the quality of existing studies. This will inform current practice in conducting and reporting micro-costing studies and lead to greater standardization in methodology in the future. Methods/Design We will perform a systematic review of the current literature on micro-costing studies of health and medical interventions, strategies, and programs. Using rigorously designed search strategies, we will search Ovid MEDLINE, EconLit, BIOSIS Previews, Embase, Scopus, and the National Health Service Economic Evaluation Database (NHS EED) to identify relevant English-language articles. These searches will be supplemented by a review of the references of relevant articles identified. Two members of the review team will independently extract detailed information on the design and characteristics of each included article using a standardized data collection form. A third reviewer will be consulted to resolve discrepancies. We will use checklists that have been developed for critical appraisal of health economics studies to evaluate the quality and potential risk of bias of included studies. Discussion This systematic review will provide useful information to help standardize the methods and techniques for conducting and reporting micro-costing studies in research, which can improve the quality and transparency of future studies and enhance comparability and interpretation of findings. In the long run, these efforts will facilitate clinical and health policy decision-making about resource allocation. Trial registration Systematic review registration: PROSPERO CRD42014007453. PMID:24887208

Modeling radiation forces acting on TOPEX/Poseidon for precision orbit determination

NASA Technical Reports Server (NTRS)

Marshall, J. A.; Luthcke, S. B.; Antreasian, P. G.; Rosborough, G. W.

1992-01-01

Geodetic satellites such as GEOSAT, SPOT, ERS-1, and TOPEX/Poseidon require accurate orbital computations to support the scientific data they collect. Until recently, gravity field mismodeling was the major source of error in precise orbit definition. However, albedo and infrared re-radiation, and spacecraft thermal imbalances produce in combination no more than a 6-cm radial root-mean-square (RMS) error over a 10-day period. This requires the development of nonconservative force models that take the satellite's complex geometry, attitude, and surface properties into account. For TOPEX/Poseidon, a 'box-wing' satellite form was investigated that models the satellite as a combination of flat plates arranged in a box shape with a connected solar array. The nonconservative forces acting on each of the eight surfaces are computed independently, yielding vector accelerations which are summed to compute the total aggregate effect on the satellite center-of-mass. In order to test the validity of this concept, 'micro-models' based on finite element analysis of TOPEX/Poseidon were used to generate acceleration histories in a wide variety of orbit orientations. These profiles are then compared to the box-wing model. The results of these simulations and their implication on the ability to precisely model the TOPEX/Poseidon orbit are discussed.

Generation of Well-Defined Micro/Nanoparticles via Advanced Manufacturing Techniques for Therapeutic Delivery

PubMed Central

Zhang, Peipei; Xia, Junfei; Luo, Sida

2018-01-01

Micro/nanoparticles have great potentials in biomedical applications, especially for drug delivery. Existing studies identified that major micro/nanoparticle features including size, shape, surface property and component materials play vital roles in their in vitro and in vivo applications. However, a demanding challenge is that most conventional particle synthesis techniques such as emulsion can only generate micro/nanoparticles with a very limited number of shapes (i.e., spherical or rod shapes) and have very loose control in terms of particle sizes. We reviewed the advanced manufacturing techniques for producing micro/nanoparticles with precisely defined characteristics, emphasizing the use of these well-controlled micro/nanoparticles for drug delivery applications. Additionally, to illustrate the vital roles of particle features in therapeutic delivery, we also discussed how the above-mentioned micro/nanoparticle features impact in vitro and in vivo applications. Through this review, we highlighted the unique opportunities in generating controllable particles via advanced manufacturing techniques and the great potential of using these micro/nanoparticles for therapeutic delivery. PMID:29670013

Morphologies and optical and electrical properties of InGaN/GaN micro-square array light-emitting diode chips.

PubMed

Han, Dan; Ma, Shufang; Jia, Zhigang; Liu, Peizhi; Jia, Wei; Shang, Lin; Zhai, Guangmei; Xu, Bingshe

2018-04-10

InGaN/GaN micro-square array light-emitting diode (LED) chips (micro-chips) have been prepared via the focused ion beam (FIB) etching technique, which can not only reduce ohmic contact degradation but also control the aspect ratio precisely in three-dimensional (3D) structure LED (3D-LED) device fabrication. The effects of FIB beam current and micro-square array depth on morphologies and optical and electrical properties of the micro-chips have been studied. Our results show that sidewall surface morphology and optical and electrical properties of the micro-chips degrade with increased beam current. After potassium hydroxide etching with different times, an optimal current-voltage and luminescence performance can be obtained. Combining the results of cathodoluminescence mappings and light output-current characteristics, the light extraction efficiency of the micro-chips is reduced as FIB etch depth increases. The mechanisms of micro-square depth on light extraction have been revealed by 3D finite difference time domain.

A machine vision system for micro-EDM based on linux

NASA Astrophysics Data System (ADS)

Guo, Rui; Zhao, Wansheng; Li, Gang; Li, Zhiyong; Zhang, Yong

2006-11-01

Due to the high precision and good surface quality that it can give, Electrical Discharge Machining (EDM) is potentially an important process for the fabrication of micro-tools and micro-components. However, a number of issues remain unsolved before micro-EDM becomes a reliable process with repeatable results. To deal with the difficulties in micro electrodes on-line fabrication and tool wear compensation, a micro-EDM machine vision system is developed with a Charge Coupled Device (CCD) camera, with an optical resolution of 1.61μm and an overall magnification of 113~729. Based on the Linux operating system, an image capturing program is developed with the V4L2 API, and an image processing program is exploited by using OpenCV. The contour of micro electrodes can be extracted by means of the Canny edge detector. Through the system calibration, the micro electrodes diameter can be measured on-line. Experiments have been carried out to prove its performance, and the reasons of measurement error are also analyzed.

Precision Control Module For UV Laser 3D Micromachining

NASA Astrophysics Data System (ADS)

Wu, Wen-Hong; Hung, Min-Wei; Chang, Chun-Li

2011-01-01

UV laser has been widely used in various micromachining such as micro-scribing or patterning processing. At present, most of the semiconductors, LEDs, photovoltaic solar panels and touch panels industries need the UV laser processing system. However, most of the UV laser processing applications in the industries utilize two dimensional (2D) plane processing. And there are tremendous business opportunities that can be developed, such as three dimensional (3D) structures of micro-electromechanical (MEMS) sensor or the precision depth control of indium tin oxide (ITO) thin films edge insulation in touch panels. This research aims to develop a UV laser 3D micromachining module that can create the novel applications for industries. By special designed beam expender in optical system, the focal point of UV laser can be adjusted quickly and accurately through the optical path control lens of laser beam expender optical system. Furthermore, the integrated software for galvanometric scanner and focal point adjustment mechanism is developed as well, so as to carry out the precise 3D microstructure machining.

Contamination Study of Micro Pulsed Plasma Thruster

DTIC Science & Technology

2008-03-01

missions ranging from nano -satellites to large spacecrafts requiring precision placement1. As an unfortunate side effect, the exhaust plume induces...the electrodes9. The electrodes have often been arranged coaxially . The system consists of electrodes, capacitors as energy storage units, a spark...increasing interest in the so-called micro- and nano -satellites, which are highly maneuverable and have lower cost. These small satellites are aimed to

Accuracy of Digital Impressions and Fitness of Single Crowns Based on Digital Impressions

PubMed Central

Yang, Xin; Lv, Pin; Liu, Yihong; Si, Wenjie; Feng, Hailan

2015-01-01

In this study, the accuracy (precision and trueness) of digital impressions and the fitness of single crowns manufactured based on digital impressions were evaluated. #14-17 epoxy resin dentitions were made, while full-crown preparations of extracted natural teeth were embedded at #16. (1) To assess precision, deviations among repeated scan models made by intraoral scanner TRIOS and MHT and model scanner D700 and inEos were calculated through best-fit algorithm and three-dimensional (3D) comparison. Root mean square (RMS) and color-coded difference images were offered. (2) To assess trueness, micro computed tomography (micro-CT) was used to get the reference model (REF). Deviations between REF and repeated scan models (from (1)) were calculated. (3) To assess fitness, single crowns were manufactured based on TRIOS, MHT, D700 and inEos scan models. The adhesive gaps were evaluated under stereomicroscope after cross-sectioned. Digital impressions showed lower precision and better trueness. Except for MHT, the means of RMS for precision were lower than 10 μm. Digital impressions showed better internal fitness. Fitness of single crowns based on digital impressions was up to clinical standard. Digital impressions could be an alternative method for single crowns manufacturing. PMID:28793417

Development of a low energy micro sheet forming machine

NASA Astrophysics Data System (ADS)

Razali, A. R.; Ann, C. T.; Shariff, H. M.; Kasim, N. I.; Musa, M. A.; Ahmad, A. F.

2017-10-01

It is expected that with the miniaturization of materials being processed, energy consumption is also being `miniaturized' proportionally. The focus of this study was to design a low energy micro-sheet-forming machine for thin sheet metal application and fabricate a low direct current powered micro-sheet-forming machine. A prototype of low energy system for a micro-sheet-forming machine which includes mechanical and electronic elements was developed. The machine was tested for its performance in terms of natural frequency, punching forces, punching speed and capability, energy consumption (single punch and frequency-time based). Based on the experiments, the machine can do 600 stroke per minute and the process is unaffected by the machine's natural frequency. It was also found that sub-Joule of power was required for a single stroke of punching/blanking process. Up to 100micron thick carbon steel shim was successfully tested and punched. It concludes that low power forming machine is feasible to be developed and be used to replace high powered machineries to form micro-products/parts.

Chalcogenide molded freeform optics for mid-infrared lasers

NASA Astrophysics Data System (ADS)

Chenard, Francois; Alvarez, Oseas; Yi, Allen

2017-05-01

High-precision chalcogenide molded micro-lenses were produced to collimate mid-infrared Quantum Cascade Lasers (QCLs). Molded cylindrical micro-lens prototypes with aspheric contour (acylindrical), high numerical aperture (NA 0.8) and small focal length (f<2 mm) were fabricated to collimate the QCL fast-axis beam. Another innovative freeform micro-lens has an input acylindrical surface to collimate the fast axis and an orthogonal output acylindrical surface to collimate the slow axis. The thickness of the freeform lens is such that the output fast- and slow-axis beams are circular. This paper presents results on the chalcogenide molded freeform micro-lens designed to collimate and circularize QCL at 4.6 microns.

Patterned graphene functionalization via mask-free scanning of micro-plasma jet under ambient condition

NASA Astrophysics Data System (ADS)

Ye, Dong; Wu, Shu-Qun; Yu, Yao; Liu, Lin; Lu, Xin-Pei; Wu, Yue

2014-03-01

In this work, a mask-free method is introduced for patterned nitrogen doping of graphene using a micro-plasma jet under ambient condition. Raman and X-ray photoelectron spectroscopy spectra indicate that nitrogen atoms are incorporated into the graphene lattice with the two-dimensional spatial distribution precisely controlled in the range of mm down to 10 μm. Since the chemistry of the micro-plasma jet can be controlled by the choice of the gas mixture, this direct writing process with micro-plasma jet can be a versatile approach for patterned functionalization of graphene with high spatial resolution. This could have promising applications in graphene-based electronics.

Small RNA sorting: matchmaking for Argonautes

PubMed Central

Czech, Benjamin; Hannon, Gregory J.

2013-01-01

Small RNAs directly or indirectly impact nearly every biological process in eukaryotic cells. To perform their myriad roles, not only must precise small RNA species be generated, but they must also be loaded into specific effector complexes called RNA-induced silencing complexes (RISCs). Argonaute proteins form the core of RISCs and different members of this large family have specific expression patterns, protein binding partners and biochemical capabilities. In this Review, we explore the mechanisms that pair specific small RNA strands with their partner proteins, with an eye towards the substantial progress that has been recently made in understanding the sorting of the major small RNA classes — microRNAs (miRNAs) and small interfering RNAs (siRNAs) — in plants and animals. PMID:21116305

Dynamic shaping of cellular membranes by phospholipids and membrane-deforming proteins.

PubMed

Suetsugu, Shiro; Kurisu, Shusaku; Takenawa, Tadaomi

2014-10-01

All cellular compartments are separated from the external environment by a membrane, which consists of a lipid bilayer. Subcellular structures, including clathrin-coated pits, caveolae, filopodia, lamellipodia, podosomes, and other intracellular membrane systems, are molded into their specific submicron-scale shapes through various mechanisms. Cells construct their micro-structures on plasma membrane and execute vital functions for life, such as cell migration, cell division, endocytosis, exocytosis, and cytoskeletal regulation. The plasma membrane, rich in anionic phospholipids, utilizes the electrostatic nature of the lipids, specifically the phosphoinositides, to form interactions with cytosolic proteins. These cytosolic proteins have three modes of interaction: 1) electrostatic interaction through unstructured polycationic regions, 2) through structured phosphoinositide-specific binding domains, and 3) through structured domains that bind the membrane without specificity for particular phospholipid. Among the structured domains, there are several that have membrane-deforming activity, which is essential for the formation of concave or convex membrane curvature. These domains include the amphipathic helix, which deforms the membrane by hemi-insertion of the helix with both hydrophobic and electrostatic interactions, and/or the BAR domain superfamily, known to use their positively charged, curved structural surface to deform membranes. Below the membrane, actin filaments support the micro-structures through interactions with several BAR proteins as well as other scaffold proteins, resulting in outward and inward membrane micro-structure formation. Here, we describe the characteristics of phospholipids, and the mechanisms utilized by phosphoinositides to regulate cellular events. We then summarize the precise mechanisms underlying the construction of membrane micro-structures and their involvements in physiological and pathological processes. Copyright © 2014 the American Physiological Society.

MicroRNAs Form Triplexes with Double Stranded DNA at Sequence-Specific Binding Sites; a Eukaryotic Mechanism via which microRNAs Could Directly Alter Gene Expression

PubMed Central

Grace, Christy R.; Ferreira, Antonio M.; Waddell, M. Brett; Ridout, Granger; Naeve, Deanna; Leuze, Michael; LoCascio, Philip F.; Panetta, John C.; Wilkinson, Mark R.; Pui, Ching-Hon; Naeve, Clayton W.; Uberbacher, Edward C.; Bonten, Erik J.; Evans, William E.

2016-01-01

MicroRNAs are important regulators of gene expression, acting primarily by binding to sequence-specific locations on already transcribed messenger RNAs (mRNA) and typically down-regulating their stability or translation. Recent studies indicate that microRNAs may also play a role in up-regulating mRNA transcription levels, although a definitive mechanism has not been established. Double-helical DNA is capable of forming triple-helical structures through Hoogsteen and reverse Hoogsteen interactions in the major groove of the duplex, and we show physical evidence (i.e., NMR, FRET, SPR) that purine or pyrimidine-rich microRNAs of appropriate length and sequence form triple-helical structures with purine-rich sequences of duplex DNA, and identify microRNA sequences that favor triplex formation. We developed an algorithm (Trident) to search genome-wide for potential triplex-forming sites and show that several mammalian and non-mammalian genomes are enriched for strong microRNA triplex binding sites. We show that those genes containing sequences favoring microRNA triplex formation are markedly enriched (3.3 fold, p<2.2 × 10−16) for genes whose expression is positively correlated with expression of microRNAs targeting triplex binding sequences. This work has thus revealed a new mechanism by which microRNAs could interact with gene promoter regions to modify gene transcription. PMID:26844769

Dewetting based fabrication of fibrous micro-scaffolds as potential injectable cell carriers.

PubMed

Song, Hokyung; Yin, Liya; Chilian, William M; Zhang Newby, Bi-Min

2015-03-01

Although regenerative medicine utilizing tissue scaffolds has made enormous strides in recent years, many constraints still hamper their effectiveness. A limitation of many scaffolds is that they form surface patches, which are not particularly effective for some types of "wounds" that are deep within tissues, e.g., stroke and myocardial infarction. In this study, we reported the generation of fibrous micro-scaffolds feasible for delivering cells by injection into the tissue parenchyma. The micro-scaffolds (widths<100μm) were made by dewetting of poly(lactic-co-glycolic acid) thin films containing parallel strips, and cells were seeded to form cell/polymer micro-constructs during or post the micro-scaffold fabrication process. Five types of cells including rat induced vascular progenitor cells were assessed for the formation of the micro-constructs. Critical factors in forming fibrous micro-scaffolds via dewetting of polymer thin films were found to be properties of polymers and supporting substrates, temperature, and proteins in the culture medium. Also, the ability of cells to attach to the micro-scaffolds was essential in forming cell/polymer micro-constructs. Both in vitro and in vivo assessments of injecting these micro-scaffolding constructs showed, as compared to free cells, enhanced cell retention at the injected site, which could lead to improved tissue engineering and regeneration. Copyright © 2014 Elsevier B.V. All rights reserved.

Simultaneous multiplexed materials characterization using a high-precision hard X-ray micro-slit array.

PubMed

Zhang, Fan; Allen, Andrew J; Levine, Lyle E; Mancini, Derrick C; Ilavsky, Jan

2015-05-01

The needs both for increased experimental throughput and for in operando characterization of functional materials under increasingly realistic experimental conditions have emerged as major challenges across the whole of crystallography. A novel measurement scheme that allows multiplexed simultaneous measurements from multiple nearby sample volumes is presented. This new approach enables better measurement statistics or direct probing of heterogeneous structure, dynamics or elemental composition. To illustrate, the submicrometer precision that optical lithography provides has been exploited to create a multiplexed form of ultra-small-angle scattering based X-ray photon correlation spectroscopy (USAXS-XPCS) using micro-slit arrays fabricated by photolithography. Multiplexed USAXS-XPCS is applied to follow the equilibrium dynamics of a simple colloidal suspension. While the dependence of the relaxation time on momentum transfer, and its relationship with the diffusion constant and the static structure factor, follow previous findings, this measurements-in-parallel approach reduces the statistical uncertainties of this photon-starved technique to below those associated with the instrument resolution. More importantly, we note the potential of the multiplexed scheme to elucidate the response of different components of a heterogeneous sample under identical experimental conditions in simultaneous measurements. In the context of the X-ray synchrotron community, this scheme is, in principle, applicable to all in-line synchrotron techniques. Indeed, it has the potential to open a new paradigm for in operando characterization of heterogeneous functional materials, a situation that will be even further enhanced by the ongoing development of multi-bend achromat storage ring designs as the next evolution of large-scale X-ray synchrotron facilities around the world.

Simultaneous multiplexed materials characterization using a high-precision hard X-ray micro-slit array

DOE PAGES

Zhang, Fan; Allen, Andrew J.; Levine, Lyle E.; ...

2015-01-01

Here, the needs both for increased experimental throughput and forin operandocharacterization of functional materials under increasingly realistic experimental conditions have emerged as major challenges across the whole of crystallography. A novel measurement scheme that allows multiplexed simultaneous measurements from multiple nearby sample volumes is presented. This new approach enables better measurement statistics or direct probing of heterogeneous structure, dynamics or elemental composition. To illustrate, the submicrometer precision that optical lithography provides has been exploited to create a multiplexed form of ultra-small-angle scattering based X-ray photon correlation spectroscopy (USAXS-XPCS) using micro-slit arrays fabricated by photolithography. Multiplexed USAXS-XPCS is applied to followmore » the equilibrium dynamics of a simple colloidal suspension. While the dependence of the relaxation time on momentum transfer, and its relationship with the diffusion constant and the static structure factor, follow previous findings, this measurements-in-parallel approach reduces the statistical uncertainties of this photon-starved technique to below those associated with the instrument resolution. More importantly, we note the potential of the multiplexed scheme to elucidate the response of different components of a heterogeneous sample underidenticalexperimental conditions in simultaneous measurements. Lastly, in the context of the X-ray synchrotron community, this scheme is, in principle, applicable to all in-line synchrotron techniques. Indeed, it has the potential to open a new paradigm for in operando characterization of heterogeneous functional materials, a situation that will be even further enhanced by the ongoing development of multi-bend achromat storage ring designs as the next evolution of large-scale X-ray synchrotron facilities around the world.« less

Multi-category micro-milling tool wear monitoring with continuous hidden Markov models

NASA Astrophysics Data System (ADS)

Zhu, Kunpeng; Wong, Yoke San; Hong, Geok Soon

2009-02-01

In-process monitoring of tool conditions is important in micro-machining due to the high precision requirement and high tool wear rate. Tool condition monitoring in micro-machining poses new challenges compared to conventional machining. In this paper, a multi-category classification approach is proposed for tool flank wear state identification in micro-milling. Continuous Hidden Markov models (HMMs) are adapted for modeling of the tool wear process in micro-milling, and estimation of the tool wear state given the cutting force features. For a noise-robust approach, the HMM outputs are connected via a medium filter to minimize the tool state before entry into the next state due to high noise level. A detailed study on the selection of HMM structures for tool condition monitoring (TCM) is presented. Case studies on the tool state estimation in the micro-milling of pure copper and steel demonstrate the effectiveness and potential of these methods.

Design of Energy Storage Management System Based on FPGA in Micro-Grid

NASA Astrophysics Data System (ADS)

Liang, Yafeng; Wang, Yanping; Han, Dexiao

2018-01-01

Energy storage system is the core to maintain the stable operation of smart micro-grid. Aiming at the existing problems of the energy storage management system in the micro-grid such as Low fault tolerance, easy to cause fluctuations in micro-grid, a new intelligent battery management system based on field programmable gate array is proposed : taking advantage of FPGA to combine the battery management system with the intelligent micro-grid control strategy. Finally, aiming at the problem that during estimation of battery charge State by neural network, initialization of weights and thresholds are not accurate leading to large errors in prediction results, the genetic algorithm is proposed to optimize the neural network method, and the experimental simulation is carried out. The experimental results show that the algorithm has high precision and provides guarantee for the stable operation of micro-grid.

Disconnected-Sea Quarks Contribution to Nucleon Electromagnetic Form Factors

NASA Astrophysics Data System (ADS)

Sufian, Raza Sabbir

We present comprehensive analysis of the light and strange disconnected-sea quarks contribution to the nucleon electric and magnetic form factors. The lattice QCD estimates of strange quark magnetic moment GsM (0) = -0.064(14)(09) microN and the mean squared charge radius E = -0.0043(16)(14) fm2 are more precise than any existing experimental measurements and other lattice calculations. The lattice QCD calculation includes ensembles across several lattice volumes and lattice spacings with one of the ensembles at the physical pion mass. We have performed a simultaneous chiral, infinite volume, and continuum extrapolation in a global fit to calculate results in the continuum limit. We find that the combined light-sea and strange quarks contribution to the nucleon magnetic moment is -0.022(11)(09) microN and to the nucleon mean square charge radius is -0.019(05)(05) fm 2. The most important outcome of this lattice QCD calculation is that while the combined light-sea and strange quarks contribution to the nucleon magnetic moment is small at about 1%, a negative 2.5(9)% contribution to the proton charge radius and a relatively larger positive 16.3(6.1)% contribution to the neutron charge radius come from the sea quarks in the nucleon. For the first time, by performing global fits, we also give predictions of the light-sea and strange quarks contributions to the nucleon electric and magnetic form factors at the physical point and in the continuum and infinite volume limits in the momentum transfer range of 0 ≤ Q2 ≤ 0.5 GeV2.

Deep Proton Writing for the rapid prototyping of polymer micro-components for optical interconnects and optofluidics

NASA Astrophysics Data System (ADS)

Van Erps, Jürgen; Vervaeke, Michael; Ottevaere, Heidi; Hermanne, Alex; Thienpont, Hugo

2013-07-01

The use of photonics in data communication and numerous other industrial applications brought plenty of prospects for innovation and opened up different unexplored market opportunities. This is a major driving force for the fabrication of micro-optical and micro-mechanical structures and their accurate alignment and integration into opto-mechanical modules and systems. To this end, we present Deep Proton Writing (DPW) as a powerful rapid prototyping technology for such micro-components. The DPW process consists of bombarding polymer samples (PMMA or SU-8) with swift protons, which results after chemical processing steps in high-quality micro-optical components. One of the strengths of the DPW micro-fabrication technology is the ability to fabricate monolithic building blocks that include micro-optical and mechanical functionalities which can be precisely integrated into more complex photonic systems. In this paper we comment on how we shifted from using 8.3 to 16.5 MeV protons for DPW and give some examples of micro-optical and micro-mechanical components recently fabricated through DPW, targeting applications in optical interconnections and in optofluidics.

Microfabrication: LIGA-X and applications

NASA Astrophysics Data System (ADS)

Kupka, R. K.; Bouamrane, F.; Cremers, C.; Megtert, S.

2000-09-01

X-ray LIGA (Lithography, Electrogrowth, Moulding) is one of today's key technologies in microfabrication and upcoming modern (meso)-(nano) fabrication, already used and anticipated for micromechanics (micromotors, microsensors, spinnerets, etc.), micro-optics, micro-hydrodynamics (fluidic devices), microbiology, in medicine, in biology, and in chemistry for microchemical reactors. It compares to micro-electromechanical systems (MEMS) technology, offering a larger, non-silicon choice of materials and better inherent precision. X-ray LIGA relies on synchrotron radiation to obtain necessary X-ray fluxes and uses X-ray proximity printing. Inherent advantages are its extreme precision, depth of field and very low intrinsic surface roughness. However, the quality of fabricated structures often depends on secondary effects during exposure and effects like resist adhesion. UV-LIGA, relying on thick UV resists is an alternative for projects requiring less precision. Modulating the spectral properties of synchrotron radiation, different regimes of X-ray lithography lead to (a) the mass-fabrication of classical nanostructures, (b) the fabrication of high aspect ratio nanostructures (HARNST), (c) the fabrication of high aspect ratio microstructures (HARMST), and (d) the fabrication of high aspect ratio centimeter structures (HARCST). Reviewing very recent activities around X-ray LIGA, we show the versatility of the method, obviously finding its region of application there, where it is best and other competing microtechnologies are less advantageous. An example of surface-based X-ray and particle lenses (orthogonal reflection optics (ORO)) made by X-ray LIGA is given.

Application of micro X-ray diffraction to investigate the reaction products formed by the alkali silica reaction in concrete structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dähn, R.; Arakcheeva, A.; Schaub, Ph.

Alkali–silica reaction (ASR) is one of the most important deterioration mechanisms in concrete leading to substantial damages of structures worldwide. Synchrotron-based micro-X-ray diffraction (micro-XRD) was employed to characterize the mineral phases formed in micro-cracks of concrete aggregates as a consequence of ASR. This particular high spatial resolution technique enables to directly gain structural information on ASR products formed in a 40-year old motorway bridge damaged due to ASR. Micro-X-ray-fluorescence was applied on thin sections to locate the reaction products formed in veins within concrete aggregates. Micro-XRD pattern were collected at selected points of interest along a vein by rotating themore » sample. Rietveld refinement determined the structure of the ASR product consisting of a new layered framework similar to mountainite and rhodesite. Furthermore, it is conceivable that understanding the structure of the ASR product may help developing new technical treatments inhibiting ASR.« less

Application of micro X-ray diffraction to investigate the reaction products formed by the alkali–silica reaction in concrete structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dähn, R., E-mail: rainer.daehn@psi.ch; Arakcheeva, A.; Schaub, Ph.

Alkali–silica reaction (ASR) is one of the most important deterioration mechanisms in concrete leading to substantial damages of structures worldwide. Synchrotron-based micro-X-ray diffraction (micro-XRD) was employed to characterize the mineral phases formed in micro-cracks of concrete aggregates as a consequence of ASR. This high spatial resolution technique enables to directly gain structural information on ASR products formed in a 40-year old motorway bridge damaged due to ASR. Micro-X-ray-fluorescence was applied on thin sections to locate the reaction products formed in veins within concrete aggregates. Micro-XRD pattern were collected at selected points of interest along a vein by rotating the sample.more » Rietveld refinement determined the structure of the ASR product consisting of a new layered framework similar to mountainite and rhodesite. It is conceivable that understanding the structure of the ASR product may help developing new technical treatments inhibiting ASR.« less

Precision Farming and Precision Pest Management: The Power of New Crop Production Technologies

PubMed Central

Strickland, R. Mack; Ess, Daniel R.; Parsons, Samuel D.

1998-01-01

The use of new technologies including Geographic Information Systems (GIS), the Global Positioning System (GPS), Variable Rate Technology (VRT), and Remote Sensing (RS) is gaining acceptance in the present high-technology, precision agricultural industry. GIS provides the ability to link multiple data values for the same geo-referenced location, and provides the user with a graphical visualization of such data. When GIS is coupled with GPS and RS, management decisions can be applied in a more precise "micro-managed" manner by using VRT techniques. Such technology holds the potential to reduce agricultural crop production costs as well as crop and environmental damage. PMID:19274236

Design of control system for optical fiber drawing machine driven by double motor

NASA Astrophysics Data System (ADS)

Yu, Yue Chen; Bo, Yu Ming; Wang, Jun

2018-01-01

Micro channel Plate (MCP) is a kind of large-area array electron multiplier with high two-dimensional spatial resolution, used as high-performance night vision intensifier. The high precision control of the fiber is the key technology of the micro channel plate manufacturing process, and it was achieved by the control of optical fiber drawing machine driven by dual-motor in this paper. First of all, utilizing STM32 chip, the servo motor drive and control circuit was designed to realize the dual motor synchronization. Secondly, neural network PID control algorithm was designed for controlling the fiber diameter fabricated in high precision; Finally, the hexagonal fiber was manufactured by this system and it shows that multifilament diameter accuracy of the fiber is +/- 1.5μm.

Prototyping for LENS

NASA Astrophysics Data System (ADS)

Rasco, B. C.

2012-03-01

The Low-Energy Neutrino Spectroscopy (LENS) experiment will precisely measure the energy spectrum of low-energy solar neutrinos via charged-current neutrino reactions on indium. The LENS detector concept applies indium-loaded scintillator in an optically-segmented lattice geometry to achieve precise time and spatial resolution with unprecedented sensitivity for low-energy neutrino events. The LENS collaboration is currently developing prototypes that aim to demonstrate the performance and selectivity of the technology and to benchmark Monte Carlo simulations that will guide scaling to the full LENS instrument. Currently a 120 liter prototype, microLENS, is operating with pure scintillator (no indium loading) in the Kimballton Underground Research Facility (KURF). We will present results from initial measurements with microLENS and plans for a 400 liter prototype, miniLENS, using indium loaded scintillator that will be installed this summer.

Optical ridge waveguides in Nd:LGS crystal produced by combination of swift C5+ ion irradiation and precise diamond blade dicing

NASA Astrophysics Data System (ADS)

Cheng, Yazhou; Lv, Jinman; Akhmadaliev, Shavkat; Zhou, Shengqiang; Chen, Feng

2016-07-01

We report on the fabrication of optical ridge waveguides in Nd:LGS crystal by using combination of swift C5+ ion irradiation and precise diamond blade dicing. The ridge structures support guidance both at 632.8 nm and 1064 nm wavelength along the TE and TM polarizations. The lowest propagation losses of the ridge waveguide for the TM mode are ~1.6 dB/cm at 632.8 nm and ~1.2 dB/cm at 1064 nm, respectively. The investigation of micro-fluorescence spectra and micro-Raman spectra indicates that the Nd3+ luminescence features have been well preserved and the microstructure of the waveguide region has no significant change after C5+ ion irradiation.

Diffractometric measurement of the temperature dependence of piezoelectric tensor in GMO monocrystal

NASA Astrophysics Data System (ADS)

Breczko, Teodor; Lempaszek, Andrzej

2007-04-01

Functional materials, of which an example is ferroelectric, ferroelastic monocrystal of molybdate (III) gadolinium (VI), are often used in the micro-motor operators (micro-servo motors) working in changeable environment conditions. Most frequently this change refers to temperature. That is why the important practical problem is the precise measurement of the value of piezoelectric tensor elements in dependence on the temperature of a particular monocrystal. In the presented article for this kind of measurements, the use of X-ray diffractometer has been shown. The advantage of the method presented is that, apart from precise dependence measurement between the temperature of a monocrystal and the value of piezoelectric tensor elements, it enables synchronous measurement of the value of thermal expansion tensor elements for a monocrystal.

Adaptive nonsingular terminal sliding mode controller for micro/nanopositioning systems driven by linear piezoelectric ceramic motors.

PubMed

Safa, Alireza; Abdolmalaki, Reza Yazdanpanah; Shafiee, Saeed; Sadeghi, Behzad

2018-06-01

In the field of nanotechnology, there is a growing demand to provide precision control and manipulation of devices with the ability to interact with complex and unstructured environments at micro/nano-scale. As a result, ultrahigh-precision positioning stages have been turned into a key requirement of nanotechnology. In this paper, linear piezoelectric ceramic motors (LPCMs) are adopted to drive micro/nanopositioning stages since they have the ability to achieve high precision in addition to being versatile to be implemented over a wide range of applications. In the establishment of a control scheme for such manipulation systems, the presence of friction, parameter uncertainties, and external disturbances prevent the systems from providing the desired positioning accuracy. The work in this paper focuses on the development of a control framework that addresses these issues as it uses the nonsingular terminal sliding mode technique for the precise position tracking problem of an LPCM-driven positioning stage with friction, uncertain parameters, and external disturbances. The developed control algorithm exhibits the following two attractive features. First, upper bounds of system uncertainties/perturbations are adaptively estimated in the proposed controller; thus, prior knowledge about uncertainty/disturbance bounds is not necessary. Second, the discontinuous signum function is transferred to the time derivative of the control input and the continuous control signal is obtained after integration; consequently, the chattering phenomenon, which presents a major handicap to the implementation of conventional sliding mode control in real applications, is alleviated without deteriorating the robustness of the system. The stability of the controlled system is analyzed, and the convergence of the position tracking error to zero is analytically proven. The proposed control strategy is experimentally validated and compared to the existing control approaches. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

Electrochemical micro/nano-machining: principles and practices.

PubMed

Zhan, Dongping; Han, Lianhuan; Zhang, Jie; He, Quanfeng; Tian, Zhao-Wu; Tian, Zhong-Qun

2017-03-06

Micro/nano-machining (MNM) is becoming the cutting-edge of high-tech manufacturing because of the increasing industrial demand for supersmooth surfaces and functional three-dimensional micro/nano-structures (3D-MNS) in ultra-large scale integrated circuits, microelectromechanical systems, miniaturized total analysis systems, precision optics, and so on. Taking advantage of no tool wear, no surface stress, environmental friendliness, simple operation, and low cost, electrochemical micro/nano-machining (EC-MNM) has an irreplaceable role in MNM. This comprehensive review presents the state-of-art of EC-MNM techniques for direct writing, surface planarization and polishing, and 3D-MNS fabrications. The key point of EC-MNM is to confine electrochemical reactions at the micro/nano-meter scale. This review will bring together various solutions to "confined reaction" ranging from electrochemical principles through technical characteristics to relevant applications.

Three techniques for the fabrication of high precision, mm-sized metal components based on two-photon lithography, applied for manufacturing horn antennas for THz transceivers

NASA Astrophysics Data System (ADS)

Standaert, Alexander; Brancato, Luigi; Lips, Bram; Ceyssens, Frederik; Puers, Robert; Reynaert, Patrick

2018-03-01

This paper proposes a novel packaging solution which integrates micro-machined 3D horn antennas with millimeter-wave and THz tranceivers. This packaging solution is shown to be a valid competitor to existing technologies like metallic split-block waveguides and low temperature cofired ceramics. Three different fabrication methods based on two-photon lithography are presented to form the horn antennas. The first uses two-photon lithography to form the bulk of the antenna. This structure is then metalised through physical vapor deposition (PVD) and copper plating. The second fabrication method makes use of a soft polydimethylsiloxane (PDMS) mold to easily replicate structures and the third method forms the horn antenna through electroforming. A prototype is accurately positioned on top of a 400 GHz 28 nm CMOS transmitter and glued in place with epoxy, thus providing a fully packaged solution. Measurement results show a 12 dB increase in the antenna gain when using the packaged solution. The fabrication processes are not limited to horn antennas alone and can be used to form a wide range of mm-sized metal components.

Experimental Study on the Effects of Alumina Abrasive Particle Behavior in MR Polishing for MEMS Applications

PubMed Central

Kim, Dong-Woo; Cho, Myeong-Woo; Seo, Tae-Il; Shin, Young-Jae

2008-01-01

Recently, the magnetorheological (MR) polishing process has been examined as a new ultra-precision polishing technology for micro parts in MEMS applications. In the MR polishing process, the magnetic force plays a dominant role. This method uses MR fluids which contains micro abrasives as a polishing media. The objective of the present research is to shed light onto the material removal mechanism under various slurry conditions for polishing and to investigate surface characteristics, including shape analysis and surface roughness measurement, of spots obtained from the MR polishing process using alumina abrasives. A series of basic experiments were first performed to determine the optimum polishing conditions for BK7 glass using prepared slurries by changing the process parameters, such as wheel rotating speed and electric current. Using the obtained results, groove polishing was then performed and the results are investigated. Outstanding surface roughness of Ra=3.8nm was obtained on the BK7 glass specimen. The present results highlight the possibility of applying this polishing method to ultra-precision micro parts production, especially in MEMS applications. PMID:27879705

Surface micro- and nano-texturing of stainless steel by femtosecond laser for the control of cell migration.

PubMed

Martínez-Calderon, M; Manso-Silván, M; Rodríguez, A; Gómez-Aranzadi, M; García-Ruiz, J P; Olaizola, S M; Martín-Palma, R J

2016-11-02

The precise control over the interaction between cells and the surface of materials plays a crucial role in optimizing the integration of implanted biomaterials. In this regard, material surface with controlled topographic features at the micro- and nano-scales has been proved to affect the overall cell behavior and therefore the final osseointegration of implants. Within this context, femtosecond (fs) laser micro/nano machining technology was used in this work to modify the surface structure of stainless steel aiming at controlling cell adhesion and migration. The experimental results show that cells tend to attach and preferentially align to the laser-induced nanopatterns oriented in a specific direction. Accordingly, the laser-based fabrication method here described constitutes a simple, clean, and scalable technique which allows a precise control of the surface nano-patterning process and, subsequently, enables the control of cell adhesion, migration, and polarization. Moreover, since our surface-patterning approach does not involve any chemical treatments and is performed in a single step process, it could in principle be applied to most metallic materials.

Surface micro- and nano-texturing of stainless steel by femtosecond laser for the control of cell migration

PubMed Central

Martínez-Calderon, M.; Manso-Silván, M.; Rodríguez, A.; Gómez-Aranzadi, M.; García-Ruiz, J. P.; Olaizola, S. M.; Martín-Palma, R. J.

2016-01-01

The precise control over the interaction between cells and the surface of materials plays a crucial role in optimizing the integration of implanted biomaterials. In this regard, material surface with controlled topographic features at the micro- and nano-scales has been proved to affect the overall cell behavior and therefore the final osseointegration of implants. Within this context, femtosecond (fs) laser micro/nano machining technology was used in this work to modify the surface structure of stainless steel aiming at controlling cell adhesion and migration. The experimental results show that cells tend to attach and preferentially align to the laser-induced nanopatterns oriented in a specific direction. Accordingly, the laser-based fabrication method here described constitutes a simple, clean, and scalable technique which allows a precise control of the surface nano-patterning process and, subsequently, enables the control of cell adhesion, migration, and polarization. Moreover, since our surface-patterning approach does not involve any chemical treatments and is performed in a single step process, it could in principle be applied to most metallic materials. PMID:27805063

Millimeter scale robots for the nanofactory

NASA Astrophysics Data System (ADS)

Murthy, Rakesh

The top down approach is a commonly employed miniaturization pathway into micro and nanomanufacturing. Its popularity is due to the fact that it adapts traditionally engineered macro scale positioning, manipulation and processing technology with micro and nano scale precision and part sizes. However, state of the art top down systems such as the Atomic Force Microscope (AFM) span four to five orders of magnitude larger than the parts being handled. This dissertation addresses the need for creating millimeter size robotic positioning technology that closes the size gap between equipment and part sizes. Such microrobot manufacturing methodology comprising of micro component-level design, fabrication and high yield assembly, system-level packaging, modeling, precision evaluation and control is presented and exemplified using two classes of microrobots. Both microrobots incorporate Micro Electro Mechanical Systems (MEMS) to combine high precision and low foot-print. The first microrobot type, the "ARRIpede" is a multi legged autonomous crawler, and is designed to operate as a mobile unit enabling parts transfer in a nanoassembly environment. An embodiment of this microrobot is demonstrated for planar motions with three degrees of freedom (XYtheta). The microrobot consists of a MEMS die "belly" spanning 10mm x 10mm x 1mm with in-plane electrothermal actuators and vertically assembled legs, and an electronic "backpack" spanning 15mmx15mmx10mm to generate a leg gait sequence. By incorporating bulk micromachined parts and precise epoxy dispensing at the assembled leg joint, the microrobot has a high payload bearing capacity (at least 9g). Simulations with a nonholonomic robot predict microcrawler velocities of a few mm/s under realistic assumptions. The open loop crawling velocity is experimentally characterized for various actuator frequencies and a close match with simulations is observed. A Linear Quadratic Regulator (LQR) based controller consisting of a high magnification camera and a laser displacement sensor for feedback is implemented. The open/closed loop positioning repeatabilities are evaluated and compared. The second micro robot called the "AFAM" (Articulated Four Axes Micro Robot) is a fixed base articulated design targeting micro and nano scale manipulation and probing applications. An embodiment of this microrobot is constructed incorporating four degrees of freedom (X, Y, Pitch and Yaw), occupying a total volume of 3mm x 2mm x 1mm, and operating within a workspace envelope of 50mum x 50mum x 75mum. This is by far the largest operating envelope of any other independent MEMS positioner with non-planar dexterity. A cable based transmission and motion amplification mechanism is designed to achieve the pitch and yaw degrees of freedom. The de-coupled motion of the microrobot is achieved by kinematic identification of the Jacobian and using a 3D flexure based kinematic model of the microrobot. By using the derived kinematics, the microrobot is driven to create nanoindents on a polymer surface. The end-effector positioning accuracy, repeatability and resolution are characterized using the nanoindents.

Investigation into Generation of Micro Features by Localised Electrochemical Deposition

NASA Astrophysics Data System (ADS)

Debnath, Subhrajit; Laskar, Hanimur Rahaman; Bhattacharyya, B.

2017-11-01

With the fast advancement of technology, localised electrochemical deposition (LECD) is becoming very advantageous in generating high aspect ratio micro features to meet the steep demand in modern precision industries of the present world. Except many other advantages, this technology is highly uncomplicated and economical for fabricating metal micro-parts with in micron ranges. In the present study, copper micro-columns have been fabricated utilizing LECD process. Different process parameters such as voltage, frequency, duty ratio and electrolyte concentration, which affect the deposition performance have been identified and their effects on deposition performances such as deposition rate, height and diameter of the micro-columns have been experimentally investigated. Taguchi's methodology has been used to study the effects as well as to obtain the optimum values of process parameters so that localised deposition with best performance can be achieved. Moreover, the generated micro-columns were carefully observed under optical and scanning electron microscope from where the surface quality of the deposited micro-columns has been studied qualitatively. Also, an array of copper micro-columns has been fabricated on stainless steel (SS-304) substrate for further exploration of LECD process capability.

Extracting alveolar structure of human lung tissue specimens based on surface skeleton representation from 3D micro-CT images

NASA Astrophysics Data System (ADS)

Ishimori, Hiroyuki; Kawata, Yoshiki; Niki, Noboru; Nakaya, Yoshihiro; Ohmatsu, Hironobu; Matsui, Eisuke; Fujii, Masashi; Moriyama, Noriyuki

2007-03-01

We have developed a Micro CT system for understanding lung function at a high resolution of the micrometer order (up to 5µm in spatial resolution). Micro CT system enables the removal specimen of lungs to be observed at micro level, has expected a big contribution for micro internal organs morphology and the image diagnosis study. In this research, we develop system to visualize lung microstructures in three dimensions from micro CT images and analyze them. They characterize in that high CT value of the noise area is, and the difficulty of only using threshold processing to extract the alveolar wall of micro CT images. Thus, we are developing a method of extracting the alveolar wall with surface thinning algorithm. In this report, we propose the method which reduces the excessive degeneracy of figure which caused by surface thinning process. And, we apply this algorithm to the micro CT image of the actual pulmonary specimen. It is shown that the extraction of the alveolus wall becomes possible in the high precision.

Determination of electron beam polarization using electron detector in Compton polarimeter with less than 1% statistical and systematic uncertainty

DOE Office of Scientific and Technical Information (OSTI.GOV)

Narayan, Amrendra

2015-05-01

The Q-weak experiment aims to measure the weak charge of proton with a precision of 4.2%. The proposed precision on weak charge required a 2.5% measurement of the parity violating asymmetry in elastic electron - proton scattering. Polarimetry was the largest experimental contribution to this uncertainty and a new Compton polarimeter was installed in Hall C at Jefferson Lab to make the goal achievable. In this polarimeter the electron beam collides with green laser light in a low gain Fabry-Perot Cavity; the scattered electrons are detected in 4 planes of a novel diamond micro strip detector while the back scatteredmore » photons are detected in lead tungstate crystals. This diamond micro-strip detector is the first such device to be used as a tracking detector in a nuclear and particle physics experiment. The diamond detectors are read out using custom built electronic modules that include a preamplifier, a pulse shaping amplifier and a discriminator for each detector micro-strip. We use field programmable gate array based general purpose logic modules for event selection and histogramming. Extensive Monte Carlo simulations and data acquisition simulations were performed to estimate the systematic uncertainties. Additionally, the Moller and Compton polarimeters were cross calibrated at low electron beam currents using a series of interleaved measurements. In this dissertation, we describe all the subsystems of the Compton polarimeter with emphasis on the electron detector. We focus on the FPGA based data acquisition system built by the author and the data analysis methods implemented by the author. The simulations of the data acquisition and the polarimeter that helped rigorously establish the systematic uncertainties of the polarimeter are also elaborated, resulting in the first sub 1% measurement of low energy (?1 GeV) electron beam polarization with a Compton electron detector. We have demonstrated that diamond based micro-strip detectors can be used for tracking in a high radiation environment and it has enabled us to achieve the desired precision in the measurement of the electron beam polarization which in turn has allowed the most precise determination of the weak charge of the proton.« less

Determination of electron beam polarization using electron detector in Compton polarimeter with less than 1% statistical and systematic uncertainty

NASA Astrophysics Data System (ADS)

Narayan, Amrendra

The Q-weak experiment aims to measure the weak charge of proton with a precision of 4.2%. The proposed precision on weak charge required a 2.5% measurement of the parity violating asymmetry in elastic electron - proton scattering. Polarimetry was the largest experimental contribution to this uncertainty and a new Compton polarimeter was installed in Hall C at Jefferson Lab to make the goal achievable. In this polarimeter the electron beam collides with green laser light in a low gain Fabry-Perot Cavity; the scattered electrons are detected in 4 planes of a novel diamond micro strip detector while the back scattered photons are detected in lead tungstate crystals. This diamond micro-strip detector is the first such device to be used as a tracking detector in a nuclear and particle physics experiment. The diamond detectors are read out using custom built electronic modules that include a preamplifier, a pulse shaping amplifier and a discriminator for each detector micro-strip. We use field programmable gate array based general purpose logic modules for event selection and histogramming. Extensive Monte Carlo simulations and data acquisition simulations were performed to estimate the systematic uncertainties. Additionally, the Moller and Compton polarimeters were cross calibrated at low electron beam currents using a series of interleaved measurements. In this dissertation, we describe all the subsystems of the Compton polarimeter with emphasis on the electron detector. We focus on the FPGA based data acquisition system built by the author and the data analysis methods implemented by the author. The simulations of the data acquisition and the polarimeter that helped rigorously establish the systematic uncertainties of the polarimeter are also elaborated, resulting in the first sub 1% measurement of low energy (~1GeV) electron beam polarization with a Compton electron detector. We have demonstrated that diamond based micro-strip detectors can be used for tracking in a high radiation environment and it has enabled us to achieve the desired precision in the measurement of the electron beam polarization which in turn has allowed the most precise determination of the weak charge of the proton.

Micro-Membrane Electrode Assembly Design to Precisely Measure the in Situ Activity of Oxygen Reduction Reaction Electrocatalysts for PEMFC.

PubMed

Long, Zhi; Li, Yankai; Deng, Guangrong; Liu, Changpeng; Ge, Junjie; Ma, Shuhua; Xing, Wei

2017-06-20

An in situ micro-MEA technique, which could precisely measure the performance of ORR electrocatalyst using Nafion as electrolyte, was designed and compared with regular thin-film rotating-disk electrode (TFRDE) (0.1 M HClO 4 ) and normal in situ membrane electrode assembly (MEA) tests. Compared to the traditional TFRDE method, the micro-MEA technique makes the acquisition of catalysts' behavior at low potential values easily achieved without being limited by the solubility of O 2 in water. At the same time, it successfully mimics the structure of regular MEAs and obtains similar results to a regular MEA, thus providing a new technique to simply measure the electrode activity without being bothered by complicated fabrication of regular MEA. In order to further understand the importance of in situ measurement, Fe-N-C as a typical oxygen reduction reaction (ORR) free-Pt catalyst was evaluated by TFRDE and micro-MEA. The results show that the half wave potential of Fe-N-C only shifted negatively by -135 mV in comparison with state-of-the-art Pt/C catalysts from TFRDE tests. However, the active site density, mass transfer of O 2 , and the proton transfer conductivity are found to strongly influence the catalyst activity in the micro-MEA, thereby resulting in a much lower limiting current density than Pt/C (8.7 times lower). Hence, it is suggested that the micro-MEA is better in evaluating the in situ ORR performance, where the catalysts are characterized more thoroughly in terms of intrinsic activity, active site density, proton transfer, and mass transfer properties.

Research Institute for Autonomous Precision Guided Systems

DTIC Science & Technology

2007-03-08

research on agile autonomous munitions, in direct support of the Air Force Research Laboratory Munitions Directorate (AFRL/MN). The grant was awarded with a...Flight had (5) research task areas: 1. Aeroforms and Actuation for Small and Micro Agile Air Vehicles 2. Sensing for Autonomous Control and...critical barriers in AAM, but are not covered in the scope of the AVCAAF (Vision-Based Control of Agile, Autonomous Micro Air Vehicles and Small UAVs

Extracellular small RNAs: what, where, why?

PubMed Central

Hoy, Anna M.; Buck, Amy H.

2012-01-01

miRNAs (microRNAs) are a class of small RNA that regulate gene expression by binding to mRNAs and modulating the precise amount of proteins that get expressed in a cell at a given time. This form of gene regulation plays an important role in developmental systems and is critical for the proper function of numerous biological pathways. Although miRNAs exert their functions inside the cell, these and other classes of RNA are found in body fluids in a cell-free form that is resistant to degradation by RNases. A broad range of cell types have also been shown to secrete miRNAs in association with components of the RISC (RNA-induced silencing complex) and/or encapsulation within vesicles, which can be taken up by other cells. In the present paper, we provide an overview of the properties of extracellular miRNAs in relation to their capacity as biomarkers, stability against degradation and mediators of cell–cell communication. PMID:22817753

Path-programmable water droplet manipulations on an adhesion controlled superhydrophobic surface

PubMed Central

Seo, Jungmok; Lee, Seoung-Ki; Lee, Jaehong; Seung Lee, Jung; Kwon, Hyukho; Cho, Seung-Woo; Ahn, Jong-Hyun; Lee, Taeyoon

2015-01-01

Here, we developed a novel and facile method to control the local water adhesion force of a thin and stretchable superhydrophobic polydimethylsiloxane (PDMS) substrate with micro-pillar arrays that allows the individual manipulation of droplet motions including moving, merging and mixing. When a vacuum pressure was applied below the PDMS substrate, a local dimple structure was formed and the water adhesion force of structure was significantly changed owing to the dynamically varied pillar density. With the help of the lowered water adhesion force and the slope angle of the formed dimple structure, the motion of individual water droplets could be precisely controlled, which facilitated the creation of a droplet-based microfluidic platform capable of a programmable manipulation of droplets. We showed that the platform could be used in newer and emerging microfluidic operations such as surface-enhanced Raman spectroscopy with extremely high sensing capability (10−15 M) and in vitro small interfering RNA transfection with enhanced transfection efficiency of ~80%. PMID:26202206

Micro Dot Patterning on the Light Guide Panel Using Powder Blasting

PubMed Central

Jang, Ho Su; Cho, Myeong Woo; Park, Dong Sam

2008-01-01

This study is to develop a micromachining technology for a light guide panel(LGP) mold, whereby micro dot patterns are formed on a LGP surface by a single injection process instead of existing screen printing processes. The micro powder blasting technique is applied to form micro dot patterns on the LGP mold surface. The optimal conditions for masking, laminating, exposure, and developing processes to form the micro dot patterns are first experimentally investigated. A LGP mold with masked micro patterns is then machined using the micro powder blasting method and the machinability of the micro dot patterns is verified. A prototype LGP is test- injected using the developed LGP mold and a shape analysis of the patterns and performance testing of the injected LGP are carried out. As an additional approach, matte finishing, a special surface treatment method, is applied to the mold surface to improve the light diffusion characteristics, uniformity and brightness of the LGP. The results of this study show that the applied powder blasting method can be successfully used to manufacture LGPs with micro patterns by just single injection using the developed mold and thereby replace existing screen printing methods. PMID:27879740

Estimating micro area behavioural risk factor prevalence from large population-based surveys: a full Bayesian approach.

PubMed

Seliske, L; Norwood, T A; McLaughlin, J R; Wang, S; Palleschi, C; Holowaty, E

2016-06-07

An important public health goal is to decrease the prevalence of key behavioural risk factors, such as tobacco use and obesity. Survey information is often available at the regional level, but heterogeneity within large geographic regions cannot be assessed. Advanced spatial analysis techniques are demonstrated to produce sensible micro area estimates of behavioural risk factors that enable identification of areas with high prevalence. A spatial Bayesian hierarchical model was used to estimate the micro area prevalence of current smoking and excess bodyweight for the Erie-St. Clair region in southwestern Ontario. Estimates were mapped for male and female respondents of five cycles of the Canadian Community Health Survey (CCHS). The micro areas were 2006 Census Dissemination Areas, with an average population of 400-700 people. Two individual-level models were specified: one controlled for survey cycle and age group (model 1), and one controlled for survey cycle, age group and micro area median household income (model 2). Post-stratification was used to derive micro area behavioural risk factor estimates weighted to the population structure. SaTScan analyses were conducted on the granular, postal-code level CCHS data to corroborate findings of elevated prevalence. Current smoking was elevated in two urban areas for both sexes (Sarnia and Windsor), and an additional small community (Chatham) for males only. Areas of excess bodyweight were prevalent in an urban core (Windsor) among males, but not females. Precision of the posterior post-stratified current smoking estimates was improved in model 2, as indicated by narrower credible intervals and a lower coefficient of variation. For excess bodyweight, both models had similar precision. Aggregation of the micro area estimates to CCHS design-based estimates validated the findings. This is among the first studies to apply a full Bayesian model to complex sample survey data to identify micro areas with variation in risk factor prevalence, accounting for spatial correlation and other covariates. Application of micro area analysis techniques helps define areas for public health planning, and may be informative to surveillance and research modeling of relevant chronic disease outcomes.

Modeling and Positioning of a PZT Precision Drive System.

PubMed

Liu, Che; Guo, Yanling

2017-11-08

The fact that piezoelectric ceramic transducer (PZT) precision drive systems in 3D printing are faced with nonlinear problems with respect to positioning, such as hysteresis and creep, has had an extremely negative impact on the precision of laser focusing systems. To eliminate the impact of PZT nonlinearity during precision drive movement, mathematical modeling and theoretical analyses of each module comprising the system were carried out in this study, a micro-displacement measurement circuit based on Position Sensitive Detector (PSD) is constructed, followed by the establishment of system closed-loop control and creep control models. An XL-80 laser interferometer (Renishaw, Wotton-under-Edge, UK) was used to measure the performance of the precision drive system, showing that system modeling and control algorithms were correct, with the requirements for precision positioning of the drive system satisfied.

Modeling and Positioning of a PZT Precision Drive System

PubMed Central

Liu, Che; Guo, Yanling

2017-01-01

The fact that piezoelectric ceramic transducer (PZT) precision drive systems in 3D printing are faced with nonlinear problems with respect to positioning, such as hysteresis and creep, has had an extremely negative impact on the precision of laser focusing systems. To eliminate the impact of PZT nonlinearity during precision drive movement, mathematical modeling and theoretical analyses of each module comprising the system were carried out in this study, a micro-displacement measurement circuit based on Position Sensitive Detector (PSD) is constructed, followed by the establishment of system closed-loop control and creep control models. An XL-80 laser interferometer (Renishaw, Wotton-under-Edge, UK) was used to measure the performance of the precision drive system, showing that system modeling and control algorithms were correct, with the requirements for precision positioning of the drive system satisfied. PMID:29117140

Deep-space navigation with differenced data types. Part 3: An expanded information content and sensitivity analysis

NASA Technical Reports Server (NTRS)

Estefan, J. A.; Thurman, S. W.

1992-01-01

An approximate six-parameter analytic model for Earth-based differential range measurements is presented and is used to derive a representative analytic approximation for differenced Doppler measurements. The analytical models are tasked to investigate the ability of these data types to estimate spacecraft geocentric angular motion, Deep Space Network station oscillator (clock/frequency) offsets, and signal-path calibration errors over a period of a few days, in the presence of systematic station location and transmission media calibration errors. Quantitative results indicate that a few differenced Doppler plus ranging passes yield angular position estimates with a precision on the order of 0.1 to 0.4 micro-rad, and angular rate precision on the order of 10 to 25 x 10(exp -12) rad/sec, assuming no a priori information on the coordinate parameters. Sensitivity analyses suggest that troposphere zenith delay calibration error is the dominant systematic error source in most of the tracking scenarios investigated; as expected, the differenced Doppler data were found to be much more sensitive to troposphere calibration errors than differenced range. By comparison, results computed using wideband and narrowband (delta) VLBI under similar circumstances yielded angular precisions of 0.07 to 0.4 micro-rad, and angular rate precisions of 0.5 to 1.0 x 10(exp -12) rad/sec.

Design and control of a macro-micro robot for precise force applications

NASA Technical Reports Server (NTRS)

Wang, Yulun; Mangaser, Amante; Laby, Keith; Jordan, Steve; Wilson, Jeff

1993-01-01

Creating a robot which can delicately interact with its environment has been the goal of much research. Primarily two difficulties have made this goal hard to attain. The execution of control strategies which enable precise force manipulations are difficult to implement in real time because such algorithms have been too computationally complex for available controllers. Also, a robot mechanism which can quickly and precisely execute a force command is difficult to design. Actuation joints must be sufficiently stiff, frictionless, and lightweight so that desired torques can be accurately applied. This paper describes a robotic system which is capable of delicate manipulations. A modular high-performance multiprocessor control system was designed to provide sufficient compute power for executing advanced control methods. An 8 degree of freedom macro-micro mechanism was constructed to enable accurate tip forces. Control algorithms based on the impedance control method were derived, coded, and load balanced for maximum execution speed on the multiprocessor system. Delicate force tasks such as polishing, finishing, cleaning, and deburring, are the target applications of the robot.

Evaluation of hybrid polymers for high-precision manufacturing of 3D optical interconnects by two-photon absorption lithography

NASA Astrophysics Data System (ADS)

Schleunitz, A.; Klein, J. J.; Krupp, A.; Stender, B.; Houbertz, R.; Gruetzner, G.

2017-02-01

The fabrication of optical interconnects has been widely investigated for the generation of optical circuit boards. Twophoton absorption (TPA) lithography (or high-precision 3D printing) as an innovative production method for direct manufacture of individual 3D photonic structures gains more and more attention when optical polymers are employed. In this regard, we have evaluated novel ORMOCER-based hybrid polymers tailored for the manufacture of optical waveguides by means of high-precision 3D printing. In order to facilitate future industrial implementation, the processability was evaluated and the optical performance of embedded waveguides was assessed. The results illustrate that hybrid polymers are not only viable consumables for industrial manufacture of polymeric micro-optics using generic processes such as UV molding. They also are potential candidates to fabricate optical waveguide systems down to the chip level where TPA-based emerging manufacturing techniques are engaged. Hence, it is shown that hybrid polymers continue to meet the increasing expectations of dynamically growing markets of micro-optics and optical interconnects due to the flexibility of the employed polymer material concept.

Enhanced optical alignment of a digital micro mirror device through Bayesian adaptive exploration

NASA Astrophysics Data System (ADS)

Wynne, Kevin B.; Knuth, Kevin H.; Petruccelli, Jonathan

2017-12-01

As the use of Digital Micro Mirror Devices (DMDs) becomes more prevalent in optics research, the ability to precisely locate the Fourier "footprint" of an image beam at the Fourier plane becomes a pressing need. In this approach, Bayesian adaptive exploration techniques were employed to characterize the size and position of the beam on a DMD located at the Fourier plane. It couples a Bayesian inference engine with an inquiry engine to implement the search. The inquiry engine explores the DMD by engaging mirrors and recording light intensity values based on the maximization of the expected information gain. Using the data collected from this exploration, the Bayesian inference engine updates the posterior probability describing the beam's characteristics. The process is iterated until the beam is located to within the desired precision. This methodology not only locates the center and radius of the beam with remarkable precision but accomplishes the task in far less time than a brute force search. The employed approach has applications to system alignment for both Fourier processing and coded aperture design.

Fabrication and Metrology of High-Precision Foil Mirror Mounting Elements

NASA Technical Reports Server (NTRS)

Schattenburg, Mark L.

2002-01-01

During the period of this Cooperative Agreement, MIT (Massachusetts Institute of Technology) developed advanced methods for applying silicon microstructures for the precision assembly of foil x-ray optics in support of the Constellation-X Spectroscopy X-ray Telescope (SXT) development effort at Goddard Space Flight Center (GSFC). MIT developed improved methods for fabricating and characterizing the precision silicon micro-combs. MIT also developed and characterized assembly tools and several types of metrology tools in order to characterize and reduce the errors associated with precision assembly of foil optics. Results of this effort were published and presented to the scientific community and the GSFC SXT team. A bibliography of papers and presentations is offered.

Wafer-scale micro-optics fabrication

NASA Astrophysics Data System (ADS)

Voelkel, Reinhard

2012-07-01

Micro-optics is an indispensable key enabling technology for many products and applications today. Probably the most prestigious examples are the diffractive light shaping elements used in high-end DUV lithography steppers. Highly-efficient refractive and diffractive micro-optical elements are used for precise beam and pupil shaping. Micro-optics had a major impact on the reduction of aberrations and diffraction effects in projection lithography, allowing a resolution enhancement from 250 nm to 45 nm within the past decade. Micro-optics also plays a decisive role in medical devices (endoscopes, ophthalmology), in all laser-based devices and fiber communication networks, bringing high-speed internet to our homes. Even our modern smart phones contain a variety of micro-optical elements. For example, LED flash light shaping elements, the secondary camera, ambient light and proximity sensors. Wherever light is involved, micro-optics offers the chance to further miniaturize a device, to improve its performance, or to reduce manufacturing and packaging costs. Wafer-scale micro-optics fabrication is based on technology established by the semiconductor industry. Thousands of components are fabricated in parallel on a wafer. This review paper recapitulates major steps and inventions in wafer-scale micro-optics technology. The state-of-the-art of fabrication, testing and packaging technology is summarized.

A Telerobot to Extend the Skill of Microsurgeons

NASA Technical Reports Server (NTRS)

Das, H.; Ohm, T.; Boswell, C.; Rodriguez, G.; Steele, R.; Charles, S.

1998-01-01

The engineering details of the Robot Assisted MicroSurgery (RAMS) telerobotic system designed to assist microsurgeons improve the precision and dexterity with which they can position surgical instruments is described in this paper.

Analytical parameters of the microplate-based ORAC-pyrogallol red assay.

PubMed

Ortiz, Rocío; Antilén, Mónica; Speisky, Hernán; Aliaga, Margarita E; López-Alarcón, Camilo

2011-01-01

The analytical parameters of the microplate-based oxygen radicals absorbance capacity (ORAC) method using pyrogallol red (PGR) as probe (ORAC-PGR) are presented. In addition, the antioxidant capacity of commercial beverages, such as wines, fruit juices, and iced teas, is estimated. A good linearity of the area under the curve (AUC) versus Trolox concentration plots was obtained [AUC = (845 +/- 110) + (23 +/- 2) [Trolox, microM], R = 0.9961, n = 19]. QC experiments showed better precision and accuracy at the highest Trolox concentration (40 microM) with RSD and REC (recuperation) values of 1.7 and 101.0%, respectively. When red wine was used as sample, the method also showed good linearity [AUC = (787 +/- 77) + (690 +/- 60) [red wine, microL/mL]; R = 0.9926, n = 17], precision and accuracy with RSD values from 1.4 to 8.3%, and REC values that ranged from 89.7 to 103.8%. Additivity assays using solutions containing gallic acid and Trolox (or red wine) showed an additive protection of PGR given by the samples. Red wines showed higher ORAC-PGR values than white wines, while the ORAC-PGR index of fruit juices and iced teas presented a great variability, ranging from 0.6 to 21.6 mM of Trolox equivalents. This variability was also observed for juices of the same fruit, showing the influence of the brand on the ORAC-PGR index. The ORAC-PGR methodology can be applied in a microplate reader with good linearity, precision, and accuracy.

A Miniaturized Colorimeter with a Novel Design and High Precision for Photometric Detection.

PubMed

Yan, Jun-Chao; Chen, Yan; Pang, Yu; Slavik, Jan; Zhao, Yun-Fei; Wu, Xiao-Ming; Yang, Yi; Yang, Si-Fan; Ren, Tian-Ling

2018-03-08

Water quality detection plays an increasingly important role in environmental protection. In this work, a novel colorimeter based on the Beer-Lambert law was designed for chemical element detection in water with high precision and miniaturized structure. As an example, the colorimeter can detect phosphorus, which was accomplished in this article to evaluate the performance. Simultaneously, a modified algorithm was applied to extend the linear measurable range. The colorimeter encompassed a near infrared laser source, a microflow cell based on microfluidic technology and a light-sensitive detector, then Micro-Electro-Mechanical System (MEMS) processing technology was used to form a stable integrated structure. Experiments were performed based on the ammonium molybdate spectrophotometric method, including the preparation of phosphorus standard solution, reducing agent, chromogenic agent and color reaction. The device can obtain a wide linear response range (0.05 mg/L up to 7.60 mg/L), a wide reliable measuring range up to 10.16 mg/L after using a novel algorithm, and a low limit of detection (0.02 mg/L). The size of flow cell in this design is 18 mm × 2.0 mm × 800 μm, obtaining a low reagent consumption of 0.004 mg ascorbic acid and 0.011 mg ammonium molybdate per determination. Achieving these advantages of miniaturized volume, high precision and low cost, the design can also be used in automated in situ detection.

A Miniaturized Colorimeter with a Novel Design and High Precision for Photometric Detection

PubMed Central

Chen, Yan; Pang, Yu; Slavik, Jan; Zhao, Yun-Fei; Wu, Xiao-Ming; Yang, Yi; Yang, Si-Fan; Ren, Tian-Ling

2018-01-01

Water quality detection plays an increasingly important role in environmental protection. In this work, a novel colorimeter based on the Beer-Lambert law was designed for chemical element detection in water with high precision and miniaturized structure. As an example, the colorimeter can detect phosphorus, which was accomplished in this article to evaluate the performance. Simultaneously, a modified algorithm was applied to extend the linear measurable range. The colorimeter encompassed a near infrared laser source, a microflow cell based on microfluidic technology and a light-sensitive detector, then Micro-Electro-Mechanical System (MEMS) processing technology was used to form a stable integrated structure. Experiments were performed based on the ammonium molybdate spectrophotometric method, including the preparation of phosphorus standard solution, reducing agent, chromogenic agent and color reaction. The device can obtain a wide linear response range (0.05 mg/L up to 7.60 mg/L), a wide reliable measuring range up to 10.16 mg/L after using a novel algorithm, and a low limit of detection (0.02 mg/L). The size of flow cell in this design is 18 mm × 2.0 mm × 800 μm, obtaining a low reagent consumption of 0.004 mg ascorbic acid and 0.011 mg ammonium molybdate per determination. Achieving these advantages of miniaturized volume, high precision and low cost, the design can also be used in automated in situ detection. PMID:29518059

Computer modelling of cyclic deformation of high-temperature materials. Technical progress report, 1 September-30 November 1993

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duesbery, M.S.

1993-11-30

This program aims at improving current methods of lifetime assessment by building in the characteristics of the micro-mechanisms known to be responsible for damage and failure. The broad approach entails the integration and, where necessary, augmentation of the micro-scale research results currently available in the literature into a macro-sale model with predictive capability. In more detail, the program will develop a set of hierarchically structured models at different length scales, from atomic to macroscopic, at each level taking as parametric input the results of the model at the next smaller scale. In this way the known microscopic properties can bemore » transported by systematic procedures to the unknown macro-scale region. It may mot be possible to eliminate empiricism completely, because some of the quantities involved cannot yet be estimated to the required degree of precision. In this case the aim will be at least to eliminate functional empiricism. Restriction of empiricism to the choice of parameters to be input to known functional forms permits some confidence in extrapolation procedures and has the advantage that the models can readily be updated as better estimates of the parameters become available.« less

From Biological Cilia to Artificial Flow Sensors: Biomimetic Soft Polymer Nanosensors with High Sensing Performance

NASA Astrophysics Data System (ADS)

Asadnia, Mohsen; Kottapalli, Ajay Giri Prakash; Karavitaki, K. Domenica; Warkiani, Majid Ebrahimi; Miao, Jianmin; Corey, David P.; Triantafyllou, Michael

2016-09-01

We report the development of a new class of miniature all-polymer flow sensors that closely mimic the intricate morphology of the mechanosensory ciliary bundles in biological hair cells. An artificial ciliary bundle is achieved by fabricating bundled polydimethylsiloxane (PDMS) micro-pillars with graded heights and electrospinning polyvinylidenefluoride (PVDF) piezoelectric nanofiber tip links. The piezoelectric nature of a single nanofiber tip link is confirmed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Rheology and nanoindentation experiments are used to ensure that the viscous properties of the hyaluronic acid (HA)-based hydrogel are close to the biological cupula. A dome-shaped HA hydrogel cupula that encapsulates the artificial hair cell bundle is formed through precision drop-casting and swelling processes. Fluid drag force actuates the hydrogel cupula and deflects the micro-pillar bundle, stretching the nanofibers and generating electric charges. Functioning with principles analogous to the hair bundles, the sensors achieve a sensitivity and threshold detection limit of 300 mV/(m/s) and 8 μm/s, respectively. These self-powered, sensitive, flexible, biocompatibale and miniaturized sensors can find extensive applications in navigation and maneuvering of underwater robots, artificial hearing systems, biomedical and microfluidic devices.

From Biological Cilia to Artificial Flow Sensors: Biomimetic Soft Polymer Nanosensors with High Sensing Performance.

PubMed

Asadnia, Mohsen; Kottapalli, Ajay Giri Prakash; Karavitaki, K Domenica; Warkiani, Majid Ebrahimi; Miao, Jianmin; Corey, David P; Triantafyllou, Michael

2016-09-13

We report the development of a new class of miniature all-polymer flow sensors that closely mimic the intricate morphology of the mechanosensory ciliary bundles in biological hair cells. An artificial ciliary bundle is achieved by fabricating bundled polydimethylsiloxane (PDMS) micro-pillars with graded heights and electrospinning polyvinylidenefluoride (PVDF) piezoelectric nanofiber tip links. The piezoelectric nature of a single nanofiber tip link is confirmed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Rheology and nanoindentation experiments are used to ensure that the viscous properties of the hyaluronic acid (HA)-based hydrogel are close to the biological cupula. A dome-shaped HA hydrogel cupula that encapsulates the artificial hair cell bundle is formed through precision drop-casting and swelling processes. Fluid drag force actuates the hydrogel cupula and deflects the micro-pillar bundle, stretching the nanofibers and generating electric charges. Functioning with principles analogous to the hair bundles, the sensors achieve a sensitivity and threshold detection limit of 300 mV/(m/s) and 8 μm/s, respectively. These self-powered, sensitive, flexible, biocompatibale and miniaturized sensors can find extensive applications in navigation and maneuvering of underwater robots, artificial hearing systems, biomedical and microfluidic devices.

PLZT Ceramic Driving Rotary Micro-mirror Based on Photoelectric-electrostatic Mechanism

NASA Astrophysics Data System (ADS)

Tang, Yujuan; Yang, Zhong; Chen, Yusong; Wang, Xinjie

2017-12-01

Based on the anomalous photovoltaic effect of PLZT, a rotary micro-mirror driven by hybrid photoelectric-electrostatic actuation of PLZT ceramic is proposed. Firstly, the mathematical modelling of coupled multi-physics fields of PLZT ceramic is established during illumination and light off phases. Then, the relationship between the rotation angle and the photovoltage of PLZT ceramics is established. In addition, the feasibility of rotary micro-mirror with hybrid photoelectric-electrostatic driving is verified via closed-loop control for photo-induced voltage of PLZT ceramic. The experimental results show that the photo-induced voltage of PLZT ceramics has good dynamic control precision using on-off closed-loop control method.

Regulation of osteoclastogenesis by gap junction communication.

PubMed

Matemba, Stephen F; Lie, Anita; Ransjö, Maria

2006-10-01

Receptor activator of NF-kappaB ligand (RANKL) is crucial in osteoclastogenesis but signaling events involved in osteoclast differentiation are far from complete and other signals may play a role in osteoclastogenesis. A more direct pathway for cellular crosstalk is provided by gap junction intercellular channel, which allows adjacent cells to exchange second messengers, ions, and cellular metabolites. Here we have investigated the role of gap junction communication in osteoclastogenesis in mouse bone marrow cultures. Immunoreactive sites for the gap junction protein connexin 43 (Cx43) were detected in the marrow stromal cells and in mature osteoclasts. Carbenoxolone (CBX) functionally blocked gap junction communication as demonstrated by a scrape loading Lucifer Yellow dye transfer technique. CBX caused a dose-dependent inhibition (significant > or = 90 microM) of the number of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells formed in 7- to 8-day marrow cultures stimulated by parathyroid hormone (PTH; 10 nM) or forskolin (FSK; 1 microM). Furthermore, CBX (100 microM) significantly inhibited prostaglandin E2 (PGE2; 10 microM) and 1,25(OH)2-vitamin D3 stimulated osteoclast differentiation in the mouse bone marrow cultures. Consequently, quantitative real-time polymerase chain reaction (PCR) analysis demonstrated that CBX downregulated the expression of osteoclast phenotypic markers, but without having any significant effects on RANK, RANKL, and osteoprotegerin (OPG) mRNA expression. However, the results demonstrated that CBX significantly inhibits RANKL-stimulated (100 ng/ml) osteoclastogenesis in the mouse bone marrow cultures. Taken together, our results suggests that gap junctional diffusion of messenger molecules interacts with signaling pathways downstream RANKL in osteoclast differentiation. Further studies are required to define the precise mechanisms and molecular targets involved. Copyright 2006 Wiley-Liss, Inc.

Quality detection system and method of micro-accessory based on microscopic vision

NASA Astrophysics Data System (ADS)

Li, Dongjie; Wang, Shiwei; Fu, Yu

2017-10-01

Considering that the traditional manual detection of micro-accessory has some problems, such as heavy workload, low efficiency and large artificial error, a kind of quality inspection system of micro-accessory has been designed. Micro-vision technology has been used to inspect quality, which optimizes the structure of the detection system. The stepper motor is used to drive the rotating micro-platform to transfer quarantine device and the microscopic vision system is applied to get graphic information of micro-accessory. The methods of image processing and pattern matching, the variable scale Sobel differential edge detection algorithm and the improved Zernike moments sub-pixel edge detection algorithm are combined in the system in order to achieve a more detailed and accurate edge of the defect detection. The grade at the edge of the complex signal can be achieved accurately by extracting through the proposed system, and then it can distinguish the qualified products and unqualified products with high precision recognition.

Fabrication of piezoelectric ceramic micro-actuator and its reliability for hard disk drives.

PubMed

Jing, Yang; Luo, Jianbin; Yang, Wenyan; Ju, Guoxian

2004-11-01

A new U-type micro-actuator for precisely positioning a magnetic head in high-density hard disk drives was proposed and developed. The micro-actuator is composed of a U-type stainless steel substrate and two piezoelectric ceramic elements. Using a high-d31 piezoelectric coefficient PMN-PZT ceramic plate and adopting reactive ion etching process fabricate the piezoelectric elements. Reliability against temperature was investigated to ensure the practical application to the drive products. The U-type substrate attached to each side via piezoelectric elements also was simulated by the finite-element method and practically measured by a laser Doppler vibrometer in order to testify the driving mechanics of it. The micro-actuator coupled with two piezoelectric elements featured large displacement of 0.875 microm and high-resonance frequency over 22 kHz. The novel piezoelectric micro-actuators then possess a useful compromise performance to displacement, resonance frequency, and generative force. The results reveal that the new design concept provides a valuable alternative for multilayer piezoelectric micro-actuators.

Microfluid oscillator based on thermocapillarity

NASA Astrophysics Data System (ADS)

Huang, Teng-chao; Shen, Yi-bing; Liu, Xu; Bai, Jian; Hou, Xiyun; Ye, Hui; Lou, Di

2004-12-01

A novel micro fluid oscillator with a boron diffused resistor is proposed in this paper. The actuation principle is based on the combination of Marangoni effect. The contemporary microfabrication technique enables us to fabricate microheater tiny enough to control temperature so quickly and precisely in micro length scale. The devices exhibiting the Marangoni effect in square channels were designed and fabricated from one silicon substrate and two quartz substrates. And the three substrates were aligned, bonded and packaged for testing. In this actuator there is a pair of micro-heaters to produce a thermal gradient along the slit. The driving wattage is about 0.1W and the resistors can make a temperature difference about 100 degrees during 0.1s with a pulsewidth of 20us for 0.1A current pulses. Then the movement is driven towards the lower temperature direction by the interfacial tension of the air-liquid interface. This micro fluid actuator can play important role in many liquid micro-systems such as in micromotor and micro valve.

A novel method for in-situ monitoring of local voltage, temperature and humidity distributions in fuel cells using flexible multi-functional micro sensors.

PubMed

Lee, Chi-Yuan; Fan, Wei-Yuan; Chang, Chih-Ping

2011-01-01

In this investigation, micro voltage, temperature and humidity sensors were fabricated and integrated for the first time on a stainless steel foil using micro-electro-mechanical systems (MEMS). These flexible multi-functional micro sensors have the advantages of high temperature resistance, flexibility, smallness, high sensitivity and precision of location. They were embedded in a proton exchange membrane fuel cell (PEMFC) and used to simultaneously measure variations in the inner voltage, temperature and humidity. The accuracy and reproducibility of the calibrated results obtained using the proposed micro sensors is excellent. The experimental results indicate that, at high current density and 100%RH or 75%RH, the relative humidity midstream and downstream saturates due to severe flooding. The performance of the PEM fuel cell can be stabilized using home-made flexible multi-functional micro sensors by the in-situ monitoring of local voltage, temperature and humidity distributions within it.

A Novel Method for In-Situ Monitoring of Local Voltage, Temperature and Humidity Distributions in Fuel Cells Using Flexible Multi-Functional Micro Sensors

PubMed Central

Lee, Chi-Yuan; Fan, Wei-Yuan; Chang, Chih-Ping

2011-01-01

In this investigation, micro voltage, temperature and humidity sensors were fabricated and integrated for the first time on a stainless steel foil using micro-electro-mechanical systems (MEMS). These flexible multi-functional micro sensors have the advantages of high temperature resistance, flexibility, smallness, high sensitivity and precision of location. They were embedded in a proton exchange membrane fuel cell (PEMFC) and used to simultaneously measure variations in the inner voltage, temperature and humidity. The accuracy and reproducibility of the calibrated results obtained using the proposed micro sensors is excellent. The experimental results indicate that, at high current density and 100%RH or 75%RH, the relative humidity midstream and downstream saturates due to severe flooding. The performance of the PEM fuel cell can be stabilized using home-made flexible multi-functional micro sensors by the in-situ monitoring of local voltage, temperature and humidity distributions within it. PMID:22319361

Real-Time 3D Ultrasound for Physiological Monitoring 22258.

DTIC Science & Technology

1999-10-01

their software to acquire positioning information using a high precision mechanical arm ( MicroScribe arm from Immersion Corp., San Jose, CA) instead of...mechanical arm (Immersion MicroScribe ™) for 3D data acquisition, also adopted by EchoTech for 3D FreeScan. • Medical quality video capture by a...MHz Dell Dimen- sion XPS computer9 (under desk), MUSTPAC-2 Vir- tual Ultrasound Probe based on the Microscribe 3D articulated arm10 (on table

UV laser-assisted wire stripping and micro-machining

NASA Astrophysics Data System (ADS)

Martyniuk, Jerry

1994-02-01

Results are reported for the use of a 266 nm frequency quadrupled Nd:YAG ultraviolet laser in the areas of wire stripping of small coaxial type transmission lines and for micro-machining of various materials including copper, glass, polyimide and DuPont TEFLONTM. This new laser is typically run with a 2 KHz repetition rate, 40 ns FWHM pulse and a fluence of about 50 joules/cm2 which makes it possible to micro-machine metals, polymers, glasses and ceramics. The high fluence of this laser allows shielding structures such as Al-MylarTM, Al-KaptonTM or the plated copper used in small coaxial cables to be precisely cut. Cut rates are reported for the above materials as well as results and photos of wire stripping and micro- machining.

Determination of phosphonoformate (foscarnet) in calf and human serum by automated solid-phase extraction and high-performance liquid chromatography with amperometric detection.

PubMed

Ba, B B; Corniot, A G; Ducint, D; Breilh, D; Grellet, J; Saux, M C

1999-03-05

An isocratic high-performance liquid chromatographic method with automated solid-phase extraction has been developed to determine foscarnet in calf and human serums. Extraction was performed with an anion exchanger, SAX, from which the analyte was eluted with a 50 mM potassium pyrophosphate buffer, pH 8.4. The mobile phase consisted of methanol-40 mM disodium hydrogenphosphate, pH 7.6 containing 0.25 mM tetrahexylammonium hydrogensulphate (25:75, v/v). The analyte was separated on a polyether ether ketone (PEEK) column 150x4.6 mm I.D. packed with Kromasil 100 C18, 5 microm. Amperometric detection allowed a quantification limit of 15 microM. The assay was linear from 15 to 240 microM. The recovery of foscarnet from calf serum ranged from 60.65+/-1.89% for 15 microM to 67.45+/-1.24% for 200 microM. The coefficient of variation was < or = 3.73% for intra-assay precision and < or =7.24% for inter-assay precision for calf serum concentrations ranged from 15 to 800 microM. For the same samples, the deviation from the nominal value ranged from -8.97% to +5.40% for same day accuracy and from -4.50% to +2.77% for day-to-day accuracy. Selectivity was satisfactory towards potential co-medications. Replacement of human serum by calf serum for calibration standards and quality control samples was validated. Automation brought more protection against biohazards and increase in productivity for routine monitoring and pharmacokinetic studies.

Impact of matric potential and pore size distribution on growth dynamics of filamentous and non-filamentous soil bacteria.

PubMed

Wolf, Alexandra B; Vos, Michiel; de Boer, Wietse; Kowalchuk, George A

2013-01-01

The filamentous growth form is an important strategy for soil microbes to bridge air-filled pores in unsaturated soils. In particular, fungi perform better than bacteria in soils during drought, a property that has been ascribed to the hyphal growth form of fungi. However, it is unknown if, and to what extent, filamentous bacteria may also display similar advantages over non-filamentous bacteria in soils with low hydraulic connectivity. In addition to allowing for microbial interactions and competition across connected micro-sites, water films also facilitate the motility of non-filamentous bacteria. To examine these issues, we constructed and characterized a series of quartz sand microcosms differing in matric potential and pore size distribution and, consequently, in connection of micro-habitats via water films. Our sand microcosms were used to examine the individual and competitive responses of a filamentous bacterium (Streptomyces atratus) and a motile rod-shaped bacterium (Bacillus weihenstephanensis) to differences in pore sizes and matric potential. The Bacillus strain had an initial advantage in all sand microcosms, which could be attributed to its faster growth rate. At later stages of the incubation, Streptomyces became dominant in microcosms with low connectivity (coarse pores and dry conditions). These data, combined with information on bacterial motility (expansion potential) across a range of pore-size and moisture conditions, suggest that, like their much larger fungal counterparts, filamentous bacteria also use this growth form to facilitate growth and expansion under conditions of low hydraulic conductivity. The sand microcosm system developed and used in this study allowed for precise manipulation of hydraulic properties and pore size distribution, thereby providing a useful approach for future examinations of how these properties influence the composition, diversity and function of soil-borne microbial communities.

The selectable hyperspectral airborne remote sensing kit (SHARK) as an enabler for precision agriculture

NASA Astrophysics Data System (ADS)

Holasek, Rick; Nakanishi, Keith; Ziph-Schatzberg, Leah; Santman, Jeff; Woodman, Patrick; Zacaroli, Richard; Wiggins, Richard

2017-04-01

Hyperspectral imaging (HSI) has been used for over two decades in laboratory research, academic, environmental and defense applications. In more recent time, HSI has started to be adopted for commercial applications in machine vision, conservation, resource exploration, and precision agriculture, to name just a few of the economically viable uses for the technology. Corning Incorporated (Corning) has been developing and manufacturing HSI sensors, sensor systems, and sensor optical engines, as well as HSI sensor components such as gratings and slits for over a decade and a half. This depth of experience and technological breadth has allowed Corning to design and develop unique HSI spectrometers with an unprecedented combination of high performance, low cost and low Size, Weight, and Power (SWaP). These sensors and sensor systems are offered with wavelength coverage ranges from the visible to the Long Wave Infrared (LWIR). The extremely low SWaP of Corning's HSI sensors and sensor systems enables their deployment using limited payload platforms such as small unmanned aerial vehicles (UAVs). This paper discusses use of the Corning patented monolithic design Offner spectrometer, the microHSI™, to build a highly compact 400-1000 nm HSI sensor in combination with a small Inertial Navigation System (INS) and micro-computer to make a complete turn-key airborne remote sensing payload. This Selectable Hyperspectral Airborne Remote sensing Kit (SHARK) has industry leading SWaP (1.5 lbs) at a disruptively low price due, in large part, to Corning's ability to manufacture the monolithic spectrometer out of polymers (i.e. plastic) and therefore reduce manufacturing costs considerably. The other factor in lowering costs is Corning's well established in house manufacturing capability in optical components and sensors that further enable cost-effective fabrication. The competitive SWaP and low cost of the microHSI™ sensor is approaching, and in some cases less than the price point of Multi Spectral Imaging (MSI) sensors. Specific designs of the Corning microHSI™ SHARK visNIR turn-key system are presented along with salient performance characteristics. Initial focus market areas include precision agriculture and historic and recent microHSI™ SHARK prototype test results are presented.

[Apatite-forming ability of pure titanium implant after micro-arc oxidation treatment].

PubMed

Tian, Zhihui; Zhang, Yu; Wang, Lichao; Nan, Kaihui

2013-10-01

To investigate the apatite forming ability of pure titanium implant after micro-arc oxidation treatment in simulated body fluid (SBF) and obtain implants with calcium phosphate (Ca-P) layers. The implants were immersed in (SBF) after micro-arc oxidation treatment for different time lengths, and their apatite forming ability and the morphology and constituents of the Ca-P layers formed on the sample surface were analyzed using X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and energy dispersive electron probe. After immersion in SBF, large quantities of Ca-P layers were induced on the surface of the samples. The Ca-P layers were composed of octacalcium phosphate and carbonated hydroxyapatite, and the crystals showed a plate-like morphology with an oriented growth. The implants with micro-arc oxidation treatment show good apatite forming ability on the surface with rich calcium and phosphorus elements. The formed layers are composed of bone-like apatite including octacalcium phosphate and carbonated hydroxyapatite.

High speed micro scanner for 3D in-volume laser micro processing

NASA Astrophysics Data System (ADS)

Schaefer, D.; Gottmann, J.; Hermans, M.; Ortmann, J.; Kelbassa, I.

2013-03-01

Using an in-house developed micro scanner three-dimensional micro components and micro fluidic devices in fused silica are realized using the ISLE process (in-volume selective laser-induced etching). With the micro scanner system the potential of high average power femtosecond lasers (P > 100 W) is exploited by the fabrication of components with micrometer precision at scan speeds of several meters per second. A commercially available galvanometer scanner is combined with an acousto-optical and/or electro-optical beam deflector and translation stages. For focusing laser radiation high numerical aperture microscope objectives (NA > 0.3) are used generating a focal volume of a few cubic micrometers. After laser exposure the materials are chemically wet etched in aqueous solution. The laser-exposed material is etched whereas the unexposed material remains nearly unchanged. Using the described technique called ISLE the fabrication of three-dimensional micro components, micro holes, cuts and channels is possible with high average power femtosecond lasers resulting in a reduced processing time for exposure. By developing the high speed micro scanner up-scaling of the ISLE process is demonstrated. The fabricated components made out of glass can be applied in various markets like biological and medical diagnostics as well as in micro mechanics.

Research on the EDM Technology for Micro-holes at Complex Spatial Locations

NASA Astrophysics Data System (ADS)

Y Liu, J.; Guo, J. M.; Sun, D. J.; Cai, Y. H.; Ding, L. T.; Jiang, H.

2017-12-01

For the demands on machining micro-holes at complex spatial location, several key technical problems are conquered such as micro-Electron Discharge Machining (micro-EDM) power supply system’s development, the host structure’s design and machining process technical. Through developing low-voltage power supply circuit, high-voltage circuit, micro and precision machining circuit and clearance detection system, the narrow pulse and high frequency six-axis EDM machining power supply system is developed to meet the demands on micro-hole discharging machining. With the method of combining the CAD structure design, CAE simulation analysis, modal test, ODS (Operational Deflection Shapes) test and theoretical analysis, the host construction and key axes of the machine tool are optimized to meet the position demands of the micro-holes. Through developing the special deionized water filtration system to make sure that the machining process is stable enough. To verify the machining equipment and processing technical developed in this paper through developing the micro-hole’s processing flow and test on the real machine tool. As shown in the final test results: the efficient micro-EDM machining pulse power supply system, machine tool host system, deionized filtration system and processing method developed in this paper meet the demands on machining micro-holes at complex spatial locations.

Ultra-high speed digital micro-mirror device based ptychographic iterative engine method

PubMed Central

Sun, Aihui; He, Xiaoliang; Kong, Yan; Cui, Haoyang; Song, Xiaojun; Xue, Liang; Wang, Shouyu; Liu, Cheng

2017-01-01

To reduce the long data acquisition time of the common mechanical scanning based Ptychographic Iterative Engine (PIE) technique, the digital micro-mirror device (DMD) is used to form the fast scanning illumination on the sample. Since the transverse mechanical scanning in the common PIE is replaced by the on/off switching of the micro-mirrors, the data acquisition time can be reduced from more than 15 minutes to less than 20 seconds for recording 12 × 10 diffraction patterns to cover the same field of 147.08 mm2. Furthermore, since the precision of DMD fabricated with the optical lithography is always higher than 10 nm (1 μm for the mechanical translation stage), the time consuming position-error-correction procedure is not required in the iterative reconstruction. These two improvements fundamentally speed up both the data acquisition and the reconstruction procedures in PIE, and relax its requirements on the stability of the imaging system, therefore remarkably improve its applicability for many practices. It is demonstrated experimentally with both USAF resolution target and biological sample that, the spatial resolution of 5.52 μm and the field of view of 147.08 mm2 can be reached with the DMD based PIE method. In a word, by using the DMD to replace the translation stage, we can effectively overcome the main shortcomings of common PIE related to the mechanical scanning, while keeping its advantages on both the high resolution and large field of view. PMID:28717560

Pseudo-enantiomeric chiral components and formation of the helical micro- and nanostructures in charge-transfer complexes

NASA Astrophysics Data System (ADS)

Langer, Jerzy J.; Hreczycho, Grzegorz

2018-03-01

Helical organic micro- and nanostructures are formed by a charge-transfer complex, cinchonidine-TCNQ. These unusual forms result from the chirality, the steric structure and specific interactions of cinchonidine molecules. These materials are semiconductors (10-4 S cm-1), with the typical absorption spectra in IR and UV-vis, but also have a characteristic of CD spectrum. Surprisingly, conductive micro and nano helices are not formed in pseudo-enantiomeric cinchonine, i.e. the complex of cinchonine and TCNQ.

Reconfigurable and responsive droplet-based compound micro-lenses.

PubMed

Nagelberg, Sara; Zarzar, Lauren D; Nicolas, Natalie; Subramanian, Kaushikaram; Kalow, Julia A; Sresht, Vishnu; Blankschtein, Daniel; Barbastathis, George; Kreysing, Moritz; Swager, Timothy M; Kolle, Mathias

2017-03-07

Micro-scale optical components play a crucial role in imaging and display technology, biosensing, beam shaping, optical switching, wavefront-analysis, and device miniaturization. Herein, we demonstrate liquid compound micro-lenses with dynamically tunable focal lengths. We employ bi-phase emulsion droplets fabricated from immiscible hydrocarbon and fluorocarbon liquids to form responsive micro-lenses that can be reconfigured to focus or scatter light, form real or virtual images, and display variable focal lengths. Experimental demonstrations of dynamic refractive control are complemented by theoretical analysis and wave-optical modelling. Additionally, we provide evidence of the micro-lenses' functionality for two potential applications-integral micro-scale imaging devices and light field display technology-thereby demonstrating both the fundamental characteristics and the promising opportunities for fluid-based dynamic refractive micro-scale compound lenses.

Reconfigurable and responsive droplet-based compound micro-lenses

PubMed Central

Nagelberg, Sara; Zarzar, Lauren D.; Nicolas, Natalie; Subramanian, Kaushikaram; Kalow, Julia A.; Sresht, Vishnu; Blankschtein, Daniel; Barbastathis, George; Kreysing, Moritz; Swager, Timothy M.; Kolle, Mathias

2017-01-01

Micro-scale optical components play a crucial role in imaging and display technology, biosensing, beam shaping, optical switching, wavefront-analysis, and device miniaturization. Herein, we demonstrate liquid compound micro-lenses with dynamically tunable focal lengths. We employ bi-phase emulsion droplets fabricated from immiscible hydrocarbon and fluorocarbon liquids to form responsive micro-lenses that can be reconfigured to focus or scatter light, form real or virtual images, and display variable focal lengths. Experimental demonstrations of dynamic refractive control are complemented by theoretical analysis and wave-optical modelling. Additionally, we provide evidence of the micro-lenses' functionality for two potential applications—integral micro-scale imaging devices and light field display technology—thereby demonstrating both the fundamental characteristics and the promising opportunities for fluid-based dynamic refractive micro-scale compound lenses. PMID:28266505

Micro Dot Patterning on the Light Guide Panel Using Powder Blasting.

PubMed

Jang, Ho Su; Cho, Myeong Woo; Park, Dong Sam

2008-02-08

This study is to develop a micromachining technology for a light guidepanel(LGP) mold, whereby micro dot patterns are formed on a LGP surface by a singleinjection process instead of existing screen printing processes. The micro powder blastingtechnique is applied to form micro dot patterns on the LGP mold surface. The optimalconditions for masking, laminating, exposure, and developing processes to form the microdot patterns are first experimentally investigated. A LGP mold with masked micro patternsis then machined using the micro powder blasting method and the machinability of themicro dot patterns is verified. A prototype LGP is test- injected using the developed LGPmold and a shape analysis of the patterns and performance testing of the injected LGP arecarried out. As an additional approach, matte finishing, a special surface treatment method,is applied to the mold surface to improve the light diffusion characteristics, uniformity andbrightness of the LGP. The results of this study show that the applied powder blastingmethod can be successfully used to manufacture LGPs with micro patterns by just singleinjection using the developed mold and thereby replace existing screen printing methods.

Initiation and growth kinetics of solidification cracking during welding of steel

PubMed Central

Aucott, L.; Huang, D.; Dong, H. B.; Wen, S. W.; Marsden, J. A.; Rack, A.; Cocks, A. C. F.

2017-01-01

Solidification cracking is a key phenomenon associated with defect formation during welding. To elucidate the failure mechanisms, solidification cracking during arc welding of steel are investigated in situ with high-speed, high-energy synchrotron X-ray radiography. Damage initiates at relatively low true strain of about 3.1% in the form of micro-cavities at the weld subsurface where peak volumetric strain and triaxiality are localised. The initial micro-cavities, with sizes from 10 × 10−6 m to 27 × 10−6 m, are mostly formed in isolation as revealed by synchrotron X-ray micro-tomography. The growth of micro-cavities is driven by increasing strain induced to the solidifying steel. Cavities grow through coalescence of micro-cavities to form micro-cracks first and then through the propagation of micro-cracks. Cracks propagate from the core of the weld towards the free surface along the solidifying grain boundaries at a speed of 2–3 × 10−3 m s−1. PMID:28074852

Fuel-Free Synthetic Micro-/Nanomachines.

PubMed

Xu, Tailin; Gao, Wei; Xu, Li-Ping; Zhang, Xueji; Wang, Shutao

2017-03-01

Inspired by the swimming of natural microorganisms, synthetic micro-/nanomachines, which convert energy into movement, are able to mimic the function of these amazing natural systems and help humanity by completing environmental and biological tasks. While offering autonomous propulsion, conventional micro-/nanomachines usually rely on the decomposition of external chemical fuels (e.g., H 2 O 2 ), which greatly hinders their applications in biologically relevant media. Recent developments have resulted in various micro-/nanomotors that can be powered by biocompatible fuels. Fuel-free synthetic micro-/nanomotors, which can move without external chemical fuels, represent another attractive solution for practical applications owing to their biocompatibility and sustainability. Here, recent developments on fuel-free micro-/nanomotors (powered by various external stimuli such as light, magnetic, electric, or ultrasonic fields) are summarized, ranging from fabrication to propulsion mechanisms. The applications of these fuel-free micro-/nanomotors are also discussed, including nanopatterning, targeted drug/gene delivery, cell manipulation, and precision nanosurgery. With continuous innovation, future autonomous, intelligent and multifunctional fuel-free micro-/nanomachines are expected to have a profound impact upon diverse biomedical applications, providing unlimited opportunities beyond one's imagination. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Investigation the gas film in micro scale induced error on the performance of the aerostatic spindle in ultra-precision machining

NASA Astrophysics Data System (ADS)

Chen, Dongju; Huo, Chen; Cui, Xianxian; Pan, Ri; Fan, Jinwei; An, Chenhui

2018-05-01

The objective of this work is to study the influence of error induced by gas film in micro-scale on the static and dynamic behavior of a shaft supported by the aerostatic bearings. The static and dynamic balance models of the aerostatic bearing are presented by the calculated stiffness and damping in micro scale. The static simulation shows that the deformation of aerostatic spindle system in micro scale is decreased. For the dynamic behavior, both the stiffness and damping in axial and radial directions are increased in micro scale. The experiments of the stiffness and rotation error of the spindle show that the deflection of the shaft resulting from the calculating parameters in the micro scale is very close to the deviation of the spindle system. The frequency information in transient analysis is similar to the actual test, and they are also higher than the results from the traditional case without considering micro factor. Therefore, it can be concluded that the value considering micro factor is closer to the actual work case of the aerostatic spindle system. These can provide theoretical basis for the design and machining process of machine tools.

Hybrid micromachining using a nanosecond pulsed laser and micro EDM

NASA Astrophysics Data System (ADS)

Kim, Sanha; Kim, Bo Hyun; Chung, Do Kwan; Shin, Hong Shik; Chu, Chong Nam

2010-01-01

Micro electrical discharge machining (micro EDM) is a well-known precise machining process that achieves micro structures of excellent quality for any conductive material. However, the slow machining speed and high tool wear are main drawbacks of this process. Though the use of deionized water instead of kerosene as a dielectric fluid can reduce the tool wear and increase the machine speed, the material removal rate (MRR) is still low. In contrast, laser ablation using a nanosecond pulsed laser is a fast and non-wear machining process but achieves micro figures of rather low quality. Therefore, the integration of these two processes can overcome the respective disadvantages. This paper reports a hybrid process of a nanosecond pulsed laser and micro EDM for micromachining. A novel hybrid micromachining system that combines the two discrete machining processes is introduced. Then, the feasibility and characteristics of the hybrid machining process are investigated compared to conventional EDM and laser ablation. It is verified experimentally that the machining time can be effectively reduced in both EDM drilling and milling by rapid laser pre-machining prior to micro EDM. Finally, some examples of complicated 3D micro structures fabricated by the hybrid process are shown.

Research on the reasonable pile spacing of micro pile composite soil nailing

NASA Astrophysics Data System (ADS)

Liu, Jun yan; Liu, Yan; Song, Xiang hua

2017-08-01

Through the numerical simulation software FLAC3D, study on the synergetic effect of micro pile composite soil nailing will be studied. By adjusting the micro pile spacing and analysing the displacement field and stress field of soil, we can find that supporting effect of the soil nail hasn’t work yet when the micro pile spacing is 2D. The soil arching between piles has been formed in the pile spacing 4D ∼ 6D. The composite effect of micro pile and soil nailing will be the best and the soil arch behind piles will be firstly formed in 6D, the horizontal saddle soil arch will be formed between the nails. The nail head coincidence pressure area and micro pile pressure area are overlapping to maintain stability in the soil between piles. When the micro pile spacing is 9D, the arch behind piles will be failure, the soil flows around, but the saddle arch between the nails into circular arch, the supporting effect of the soil nailing is enhanced. When the micro pile spacing is 12D, the arch of the nails becomes smaller, sliding surface appears primitively. Based on the conclusions above, it is suggested that the micro pile spacing between 2D ∼ 6D is suitable for the micro pile and soil nailing composite support. The conclusion can provide theoretical basis for the design and construction of micro pile composite soil nailing.

Estimation of genetic variance for macro- and micro-environmental sensitivity using double hierarchical generalized linear models.

PubMed

Mulder, Han A; Rönnegård, Lars; Fikse, W Freddy; Veerkamp, Roel F; Strandberg, Erling

2013-07-04

Genetic variation for environmental sensitivity indicates that animals are genetically different in their response to environmental factors. Environmental factors are either identifiable (e.g. temperature) and called macro-environmental or unknown and called micro-environmental. The objectives of this study were to develop a statistical method to estimate genetic parameters for macro- and micro-environmental sensitivities simultaneously, to investigate bias and precision of resulting estimates of genetic parameters and to develop and evaluate use of Akaike's information criterion using h-likelihood to select the best fitting model. We assumed that genetic variation in macro- and micro-environmental sensitivities is expressed as genetic variance in the slope of a linear reaction norm and environmental variance, respectively. A reaction norm model to estimate genetic variance for macro-environmental sensitivity was combined with a structural model for residual variance to estimate genetic variance for micro-environmental sensitivity using a double hierarchical generalized linear model in ASReml. Akaike's information criterion was constructed as model selection criterion using approximated h-likelihood. Populations of sires with large half-sib offspring groups were simulated to investigate bias and precision of estimated genetic parameters. Designs with 100 sires, each with at least 100 offspring, are required to have standard deviations of estimated variances lower than 50% of the true value. When the number of offspring increased, standard deviations of estimates across replicates decreased substantially, especially for genetic variances of macro- and micro-environmental sensitivities. Standard deviations of estimated genetic correlations across replicates were quite large (between 0.1 and 0.4), especially when sires had few offspring. Practically, no bias was observed for estimates of any of the parameters. Using Akaike's information criterion the true genetic model was selected as the best statistical model in at least 90% of 100 replicates when the number of offspring per sire was 100. Application of the model to lactation milk yield in dairy cattle showed that genetic variance for micro- and macro-environmental sensitivities existed. The algorithm and model selection criterion presented here can contribute to better understand genetic control of macro- and micro-environmental sensitivities. Designs or datasets should have at least 100 sires each with 100 offspring.

Micro-Arcsec mission: implications of the monitoring, diagnostic and calibration of the instrument response in the data reduction chain. .

NASA Astrophysics Data System (ADS)

Busonero, D.; Gai, M.

The goals of 21st century high angular precision experiments rely on the limiting performance associated to the selected instrumental configuration and observational strategy. Both global and narrow angle micro-arcsec space astrometry require that the instrument contributions to the overall error budget has to be less than the desired micro-arcsec level precision. Appropriate modelling of the astrometric response is required for optimal definition of the data reduction and calibration algorithms, in order to ensure high sensitivity to the astrophysical source parameters and in general high accuracy. We will refer to the framework of the SIM-Lite and the Gaia mission, the most challenging space missions of the next decade in the narrow angle and global astrometry field, respectively. We will focus our dissertation on the Gaia data reduction issues and instrument calibration implications. We describe selected topics in the framework of the Astrometric Instrument Modelling for the Gaia mission, evidencing their role in the data reduction chain and we give a brief overview of the Astrometric Instrument Model Data Analysis Software System, a Java-based pipeline under development by our team.

High strength fused silica flexures manufactured by femtosecond laser

NASA Astrophysics Data System (ADS)

Bellouard, Yves; Said, Ali A.; Dugan, Mark; Bado, Philippe

2009-02-01

Flexures are mechanical elements used in micro- and precision-engineering to precisely guide the motion of micro-parts. They consist of slender bodies that deform elastically upon the application of a force. Although counter-intuitive at first, fused silica is an attractive material for flexure. Pending that the machining process does not introduce surface flaws that would lead to catastrophic failure, the material has a theoretically high ultimate tensile strength of several GPa. We report on high-aspect ratio fused silica flexures manufactured by femtosecond laser combined with chemical etching. Notch-hinges with thickness as small as twenty microns and aspect ratios comparable to aspect ratios obtained by Deep- Reactive-Ion-Etching (DRIE) were fabricated and tested under different loading conditions. Multiple fracture tests were performed for various loading conditions and the cracks morphologies were analyzed using Scanning Electron Microscopy. The manufactured elements show outstanding mechanical properties with flexural strengths largely exceeding those obtained with other technologies and materials. Fused silica flexures offer a mean to combine integrated optics with micro-mechanics in a single monolithic substrate. Waveguides and mechanical elements can be combined in a monolithic devices opening new opportunities for integrated opto-mechatronics devices.

MicroBioRobots for single cell manipulation

NASA Astrophysics Data System (ADS)

Sakar, Mahmut Selman

One of the great challenges in nano and micro scale science and engineering is the independent manipulation of biological cells and small man-made objects with active sensing. For such biomedical applications as single cell manipulation, telemetry, and localized targeted delivery of chemicals, it is important to fabricate microstructures that can be powered and controlled without a tether in fluidic environments. These microstructures can be used to develop microrobots that have the potential to make existing therapeutic and diagnostic procedures less invasive. Actuation can be realized using various different organic and inorganic methods. Previous studies explored different forms of actuation and control with microorganisms. Bacteria, in particular, offer several advantages as controllable microactuators: they draw chemical energy directly from their environment, they are genetically modifiable, and they are scalable and configurable in the sense that any number of bacteria can be selectively patterned. Additionally, the study of bacteria inspires inorganic schemes of actuation and control. For these reasons, we chose to employ bacteria while controlling their motility using optical and electrical stimuli. In the first part of the thesis, we demonstrate a biointegrated approach by introducing MicroBioRobots (MBRs). MBRs are negative photosensitive epoxy (SU8) microfabricated structures with typical feature sizes ranging from 1-100 mum coated with a monolayer of the swarming Serratia marcescens . The adherent bacterial cells naturally coordinate to propel the microstructures in fluidic environments which we call Self-Actuation. First, we demonstrate the control of MBRs using self-actuation, DC electric fields and ultra-violet radiation and develop an experimentally-validated mathematical model for the MBRs. This model allows us to to steer the MBR to any position and orientation in a planar micro channel using visual feedback and an inverted microscope. Examples of sub-micron scale transport and assembly as well as computer-based closed-loop control of MBRs are presented. We demonstrate experimentally that vision-based feedback control allows a four-electrode experimental device to steer MBRs along arbitrary paths with micrometer precision. At each time instant, the system identifies the current location of the robot, a control algorithm determines the power supply voltages that will move the charged robot from its current location toward its next desired position, and the necessary electric field is then created. Second, we develop biosensors for the MBRs. Microscopic devices with sensing capabilities could significantly improve single cell analysis, especially in high-resolution detection of patterns of chemicals released from cells in vitro. Two different types of sensing mechanisms are employed. The first method is based on harnessing bacterial power, and in the second method we use genetically engineered bacteria. The small size of the devices gives them access to individual cells, and their large numbers permit simultaneous monitoring of many cells. In the second part, we describe the construction and operation of truly micron-sized, biocompatible ferromagnetic micro transporters driven by external magnetic fields capable of exerting forces at the pico Newton scale. We develop micro transporters using a simple, single step micro fabrication technique that allows us to produce large numbers in the same step. We also fabricate microgels to deliver drugs. We demonstrate that the micro transporters can be navigated to separate single cells with micron-size precision and localize microgels without disturbing the local environment.

Recent Results from ArgoNeuT and Status of MicroBooNE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Szelc, Andrzej

2015-07-10

Liquid Argon Time Projection Chamber (LArTPC) detectors hold the key to answering the outstanding questions about the role of neutrinos in the Standard Model of Particle physics and beyond. Their fine granularity combined with calorimetric capabilities allows for precision measurements that answering these questions will require. Here, we discuss the recent results from the ArgoNeuT experiment as well as the status and prospects for MicroBooNE, both a part of the US-based LArTPC neutrino program.

Design and realization of sort manipulator of crystal-angle sort machine

NASA Astrophysics Data System (ADS)

Wang, Ming-shun; Chen, Shu-ping; Guan, Shou-ping; Zhang, Yao-wei

2005-12-01

It is a current tendency of development in automation technology to replace manpower with manipulators in working places where dangerous, harmful, heavy or repetitive work is involved. The sort manipulator is installed in a crystal-angle sort machine to take the place of manpower, and engaged in unloading and sorting work. It is the outcome of combing together mechanism, electric transmission, and pneumatic element and micro-controller control. The step motor makes the sort manipulator operate precisely. The pneumatic elements make the sort manipulator be cleverer. Micro-controller's software bestows some simple artificial intelligence on the sort manipulator, so that it can precisely repeat its unloading and sorting work. The combination of manipulator's zero position and step motor counting control puts an end to accumulating error in long time operation. A sort manipulator's design in the practice engineering has been proved to be correct and reliable.

Fabrication of polymer micro-lens array with pneumatically diaphragm-driven drop-on-demand inkjet technology.

PubMed

Xie, Dan; Zhang, Honghai; Shu, Xiayun; Xiao, Junfeng

2012-07-02

The paper reports an effective method to fabricate micro-lens arrays with the ultraviolet-curable polymer, using an original pneumatically diaphragm-driven drop-on-demand inkjet system. An array of plano convex micro-lenses can be formed on the glass substrate due to surface tension and hydrophobic effect. The micro-lens arrays have uniform focusing function, smooth and real planar surface. The fabrication process showed good repeatability as well, fifty micro-lenses randomly selected form 9 × 9 miro-lens array with an average diameter of 333.28μm showed 1.1% variations. Also, the focal length, the surface roughness and optical property of the fabricated micro-lenses are measured, analyzed and proved satisfactory. The technique shows great potential for fabricating polymer micro-lens arrays with high flexibility, simple technological process and low production cost.

Micro devices using shape memory polymer patches for mated connections

DOEpatents

Lee, Abraham P.; Fitch, Joseph P.

2000-01-01

A method and micro device for repositioning or retrieving miniature devices located in inaccessible areas, such as medical devices (e.g., stents, embolic coils, etc.) located in a blood vessel. The micro repositioning or retrieving device and method uses shape memory polymer (SMP) patches formed into mating geometries (e.g., a hoop and a hook) for re-attachment of the deposited medical device to a catheter or guidewire. For example, SMP or other material hoops are formed on the medical device to be deposited in a blood vessel, and SMP hooks are formed on the micro device attached to a guidewire, whereby the hooks on the micro device attach to the hoops on the medical device, or vice versa, enabling deposition, movement, re-deposit, or retrieval of the medical device. By changing the temperature of the SMP hooks, the hooks can be attached to or released from the hoops located on the medical device. An exemplary method for forming the hooks and hoops involves depositing a sacrificial thin film on a substrate, patterning and processing the thin film to form openings therethrough, depositing or bonding SMP materials in the openings so as to be attached to the substrate, and removing the sacrificial thin film.

A novel integrated multifunction micro-sensor for three-dimensional micro-force measurements.

PubMed

Wang, Weizhong; Zhao, Yulong; Qin, Yafei

2012-01-01

An integrated multifunction micro-sensor for three-dimensional micro-force precision measurement under different pressure and temperature conditions is introduced in this paper. The integrated sensor consists of three kinds of sensors: a three-dimensional micro-force sensor, an absolute pressure sensor and a temperature sensor. The integrated multifunction micro-sensor is fabricated on silicon wafers by micromachining technology. Different doping doses of boron ion, placement and structure of resistors are tested for the force sensor, pressure sensor and temperature sensor to minimize the cross interference and optimize the properties. A glass optical fiber, with a ladder structure and sharp tip etched by buffer oxide etch solution, is glued on the micro-force sensor chip as the tactile probe. Experimental results show that the minimum force that can be detected by the force sensor is 300 nN; the lateral sensitivity of the force sensor is 0.4582 mV/μN; the probe length is linearly proportional to sensitivity of the micro-force sensor in lateral; the sensitivity of the pressure sensor is 0.11 mv/KPa; the sensitivity of the temperature sensor is 5.836 × 10(-3) KΩ/°C. Thus it is a cost-effective method to fabricate integrated multifunction micro-sensors with different measurement ranges that could be used in many fields.

Wafer-level micro-optics: trends in manufacturing, testing, packaging, and applications

NASA Astrophysics Data System (ADS)

Voelkel, Reinhard; Gong, Li; Rieck, Juergen; Zheng, Alan

2012-11-01

Micro-optics is an indispensable key enabling technology (KET) for many products and applications today. Probably the most prestigious examples are the diffractive light shaping elements used in high-end DUV lithography steppers. Highly efficient refractive and diffractive micro-optical elements are used for precise beam and pupil shaping. Micro-optics had a major impact on the reduction of aberrations and diffraction effects in projection lithography, allowing a resolution enhancement from 250 nm to 45 nm within the last decade. Micro-optics also plays a decisive role in medical devices (endoscopes, ophthalmology), in all laser-based devices and fiber communication networks (supercomputer, ROADM), bringing high-speed internet to our homes (FTTH). Even our modern smart phones contain a variety of micro-optical elements. For example, LED flashlight shaping elements, the secondary camera, and ambient light and proximity sensors. Wherever light is involved, micro-optics offers the chance to further miniaturize a device, to improve its performance, or to reduce manufacturing and packaging costs. Wafer-scale micro-optics fabrication is based on technology established by semiconductor industry. Thousands of components are fabricated in parallel on a wafer. We report on the state of the art in wafer-based manufacturing, testing, packaging and present examples and applications for micro-optical components and systems.

Fabrication of locally micro-structured fiber Bragg gratings by fs-laser machining

NASA Astrophysics Data System (ADS)

Dutz, Franz J.; Stephan, Valentin; Marchi, Gabriele; Koch, Alexander W.; Roths, Johannes; Huber, Heinz P.

2018-06-01

Here, we describe a method for producing locally micro-structured fiber Bragg gratings (LMFGB) by fs-laser machining. This technique enables the precise and reproducible ablation of cladding material to create circumferential grooves inside the claddings of optical fibers. From initial ablation experiments we acquired optimized process parameters. The fabricated grooves were located in the middle of uniform type I fiber Bragg gratings. LMFBGs with four different groove widths of 48, 85, 135 and 205 μ { {m}} were produced. The grooves exhibited constant depths of about 30 μ {m} and steep sidewall angles. With the combination of micro-structures and fiber Bragg gratings, fiber optic sensor elements with enhanced functionalities can be achieved.

A macro-micro robot for precise force applications

NASA Technical Reports Server (NTRS)

Marzwell, Neville I.; Wang, Yulun

1993-01-01

This paper describes an 8 degree-of-freedom macro-micro robot capable of performing tasks which require accurate force control. Applications such as polishing, finishing, grinding, deburring, and cleaning are a few examples of tasks which need this capability. Currently these tasks are either performed manually or with dedicated machinery because of the lack of a flexible and cost effective tool, such as a programmable force-controlled robot. The basic design and control of the macro-micro robot is described in this paper. A modular high-performance multiprocessor control system was designed to provide sufficient compute power for executing advanced control methods. An 8 degree of freedom macro-micro mechanism was constructed to enable accurate tip forces. Control algorithms based on the impedance control method were derived, coded, and load balanced for maximum execution speed on the multiprocessor system.

Human iris three-dimensional imaging at micron resolution by a micro-plenoptic camera

PubMed Central

Chen, Hao; Woodward, Maria A.; Burke, David T.; Jeganathan, V. Swetha E.; Demirci, Hakan; Sick, Volker

2017-01-01

A micro-plenoptic system was designed to capture the three-dimensional (3D) topography of the anterior iris surface by simple single-shot imaging. Within a depth-of-field of 2.4 mm, depth resolution of 10 µm can be achieved with accuracy (systematic errors) and precision (random errors) below 20%. We demonstrated the application of our micro-plenoptic imaging system on two healthy irides, an iris with naevi, and an iris with melanoma. The ridges and folds, with height differences of 10~80 µm, on the healthy irides can be effectively captured. The front surface on the iris naevi was flat, and the iris melanoma was 50 ± 10 µm higher than the surrounding iris. The micro-plenoptic imaging system has great potential to be utilized for iris disease diagnosis and continuing, simple monitoring. PMID:29082081

Human iris three-dimensional imaging at micron resolution by a micro-plenoptic camera.

PubMed

Chen, Hao; Woodward, Maria A; Burke, David T; Jeganathan, V Swetha E; Demirci, Hakan; Sick, Volker

2017-10-01

A micro-plenoptic system was designed to capture the three-dimensional (3D) topography of the anterior iris surface by simple single-shot imaging. Within a depth-of-field of 2.4 mm, depth resolution of 10 µm can be achieved with accuracy (systematic errors) and precision (random errors) below 20%. We demonstrated the application of our micro-plenoptic imaging system on two healthy irides, an iris with naevi, and an iris with melanoma. The ridges and folds, with height differences of 10~80 µm, on the healthy irides can be effectively captured. The front surface on the iris naevi was flat, and the iris melanoma was 50 ± 10 µm higher than the surrounding iris. The micro-plenoptic imaging system has great potential to be utilized for iris disease diagnosis and continuing, simple monitoring.

[A micro-silicon multi-slit spectrophotometer based on MEMS technology].

PubMed

Hao, Peng; Wu, Yi-Hui; Zhang, Ping; Liu, Yong-Shun; Zhang, Ke; Li, Hai-Wen

2009-06-01

A new mini-spectrophotometer was developed by adopting micro-silicon slit and pixel segmentation technology, and this spectrophotometer used photoelectron diode array as the detector by the back-dividing-light way. At first, the effect of the spectral bandwidth on the tested absorbance linear correlation was analyzed. A theory for the design of spectrophotometer's slit was brought forward after discussing the relationships between spectrophotometer spectrum band width and pre-and post-slits width. Then, the integrative micro-silicon-slit, which features small volume, high precision, and thin thickness, was manufactured based on the MEMS technology. Finally, a test was carried on linear absorbance solution by this spectrophotometer. The final result showed that the correlation coefficients were larger than 0.999, which means that the new mini-spectrophotometer with micro-silicon slit pixel segmentation has an obvious linear correlation.

Modeling and control for micro and nano manipulation

NASA Astrophysics Data System (ADS)

Wejinya, Uchechukwu C.

Manipulation of micro and nano entities implies the movement of micro and nano entities from an initial position (location) to the desire position (location). This operation is not only necessary, but a required task with great precision. The tools needed for the manipulation needs to be chosen properly because the capabilities of the human hand are very restricted. Smart micro and nano manipulation are becoming of great interest in many applications including medicine and industry. In industry, high precision manipulation systems are especially needed for mass production of both micro and nano systems which consist of different component in respective scales. The transition from assembling and manipulating micro and nano entities manually to mass products with high quality is only attainable by automated assembly and manipulation systems. An example is the testing of integrated circuits which can be carried out by exchanging the manipulation tool by an electric probe. Furthermore, in medical research it is customary to pick up a single cell (human, plant, or animal), and carry it to another device which is used to further analyze the cell. Consequently, the cell of interest has to be separated from the other cells and picked up using the appropriate micro/nano tool. Hence it becomes absolutely necessary that the appropriate tool be used for specific micro or nano entity manipulation and assembly. In this research, we focus on developing micro tool for manipulating micro and nano entities in liquid environment using a micro fluidic end effector system with in-situ Polyvinylidene Fluoride (PVDF) sensing. The microfluidic end effector system consists of a DC micro-diaphragm pump and compressor, one region of flexible latex tube, a Polyvinylidene Fluoride (PVDF) sensor for in-situ measurement of micro drag force, and a micro pipette. The micro pipette of the novel microfluidic end effector system has an internal diameter (ID) smaller than 20mum used for microfluidic handling and deposition of micro and nano entities such as carbon nanotubes (CNT), DNA, and for droplet control. The novel microfluidic end effector system with force sensing can significantly improve the success rate for handling/depositing micro/nano entities in the case of carbon nanotubes between micro electrodes. The design, calibration, and experimental implementation of the novel microfluidic end effector is carried out in this research. The experimental results show the success rate for carbon nanotube(s) deposition between micro electrodes can reach close to 80%. Furthermore, carbon nanotubes are of particular interest because they are good candidates for many electronics and sensing applications. The interests in using carbon nanotubes to manufacture electronics and sensors have increased in recent years because of the increase need for making electronics smaller, and their excellent electrical and mechanical properties. These potentials can be achieved if CNTs with semiconducting and metallic band structure can be successfully deposited and separated. The use of dielectrophoresis (DEP) has been established as a course towards the efficient deposition and separation of metallic carbon nanotubes from semiconducting carbon nanotubes. For this reason, this research presents a new mathematical model for dielectrophoresis and electrorotation of carbon nanotubes. Simulation results are presented in this research to validate the developed model. The combination of both the micro robotic manipulation system and the atomic force microscopy (AFM) based nano-robotic system will provide a powerful tool for micro and nano manipulation. Additional applications of this research are endless considering the rapid development of micro and nano technologies.

Printing medicines as orodispersible dosage forms: Effect of substrate on the printed micro-structure.

PubMed

Planchette, C; Pichler, H; Wimmer-Teubenbacher, M; Gruber, M; Gruber-Woelfler, H; Mohr, S; Tetyczka, C; Hsiao, W-K; Paudel, A; Roblegg, E; Khinast, J

2016-07-25

We present our recent advancements in developing a viable manufacturing process for printed medicine. Our approach involves using a non-contact printing system that incorporates both piezoelectric- and solenoid valve-based inkjet printing technologies, to deliver both active and inactive pharmaceutical materials onto medical-graded orodispersible films. By using two complimentary inkjet technologies, we were able to dispense an extensive range of fluids, from aqueous drug solutions to viscous polymer coating materials. Essentially, we demonstrate printing of a wide range of formulations for patient-ready, orodispersible drug dosage forms, without the risk of drug degradation by ink heating and of substrate damages (by contact printing). In addition, our printing process has been optimized to ensure that the drug doses can be loaded onto the orally dissolvable films without introducing defects, such as holes or tears, while retaining a smooth surface texture that promotes patient adherence and allows for uniform post-coatings. Results show that our platform technology can address key issues in manufacturing orodispersible drug dosage forms and bring us closer to delivering personalized and precision medicine to targeted patient populations. Copyright © 2015 Elsevier B.V. All rights reserved.

Formation and Growth of Micro and Macro Bubbles on Copper-Graphite Composite Surfaces

NASA Technical Reports Server (NTRS)

Chao, David F.; Sankovic, John M.; Motil, Brian J.; Zhang, Nengli

2007-01-01

Micro scale boiling behavior in the vicinity of graphite micro-fiber tips on the coppergraphite composite boiling surfaces is investigated. It is discovered that a large number of micro bubbles are formed first at the micro scratches and cavities on the copper matrix in pool boiling. In virtue of the non-wetting property of graphite, once the growing micro bubbles touch the graphite tips, the micro bubbles are sucked by the tips and merged into larger micro bubbles sitting on the tips. The micro bubbles grow rapidly and coalesce to form macro bubbles, each of which sitting on several tips. The growth processes of the micro and macro bubbles are analyzed and formulated followed by an analysis of bubble departure on the composite surfaces. Based on these analyses, the enhancement mechanism of the pool boiling heat transfer on the composite surfaces is clearly revealed. Experimental results of pool boiling heat transfer both for water and Freon-113 on the composite surfaces convincingly demonstrate the enhancement effects of the unique structure of Cu-Gr composite surfaces on boiling heat transfer.

Responsive upper limb and cognitive fatigue measures during light precision work: an 8-hour simulated micro-pipetting study.

PubMed

Yung, Marcus; Wells, Richard P

2017-07-01

Many contemporary occupations are characterised by long periods of low loads. These lower force levels, which are relevant to the development of work-related musculoskeletal disorders, are usually not the focus of fatigue studies. In studies that did measure fatigue in light manual or precision work, within and between measurement responses were inconsistent. The aim of this study was to identify fatigue measures that were responsive at lower force levels (<10% MVC) over the course of an 8-h period. A complementary set of fatigue measures, reflecting both neuromuscular and cognitive mechanisms, was measured during a light precision micro-pipetting task performed by 11 participants. Nine measures were found to be significantly responsive over the 8-h period, including: ratings of perceived fatigue, postural tremor, blink frequency and critical flicker fusion frequency threshold. Common field measures, specifically electromyography RMS amplitude and maximum voluntary contractions, did not lead to extraordinary time effects. Practitioner summary: The findings provide insight towards the responsiveness of a complementary set of field usable fatigue measures at low work intensities Although commonly used measures did not reveal significant increases in fatigue, nine alternative measures were significantly responsive over the 8-h period.

Convergent microRNA actions coordinate neocortical development.

PubMed

Barca-Mayo, Olga; De Pietri Tonelli, Davide

2014-08-01

Neocortical development is a complex process that, at the cellular level, involves tight control of self-renewal, cell fate commitment, survival, differentiation and delamination/migration. These processes require, at the molecular level, the precise regulation of intrinsic signaling pathways and extrinsic factors with coordinated action in a spatially and temporally specific manner. Transcriptional regulation plays an important role during corticogenesis; however, microRNAs (miRNAs) are emerging as important post-transcriptional regulators of various aspects of central nervous system development. miRNAs are a class of small, single-stranded noncoding RNA molecules that control the expression of the majority of protein coding genes (i.e., targets). How do different miRNAs achieve precise control of gene networks during neocortical development? Here, we critically review all the miRNA-target interactions validated in vivo, with relevance to the generation and migration of pyramidal-projection glutamatergic neurons, and for the initial formation of cortical layers in the embryonic development of rodent neocortex. In particular, we focus on convergent miRNA actions, which are still a poorly understood layer of complexity in miRNA signaling, but potentially one of the keys to disclosing how miRNAs achieve the precise coordination of complex biological processes such as neocortical development.

Microscopic vision modeling method by direct mapping analysis for micro-gripping system with stereo light microscope.

PubMed

Wang, Yuezong; Zhao, Zhizhong; Wang, Junshuai

2016-04-01

We present a novel and high-precision microscopic vision modeling method, which can be used for 3D data reconstruction in micro-gripping system with stereo light microscope. This method consists of four parts: image distortion correction, disparity distortion correction, initial vision model and residual compensation model. First, the method of image distortion correction is proposed. Image data required by image distortion correction comes from stereo images of calibration sample. The geometric features of image distortions can be predicted though the shape deformation of lines constructed by grid points in stereo images. Linear and polynomial fitting methods are applied to correct image distortions. Second, shape deformation features of disparity distribution are discussed. The method of disparity distortion correction is proposed. Polynomial fitting method is applied to correct disparity distortion. Third, a microscopic vision model is derived, which consists of two models, i.e., initial vision model and residual compensation model. We derive initial vision model by the analysis of direct mapping relationship between object and image points. Residual compensation model is derived based on the residual analysis of initial vision model. The results show that with maximum reconstruction distance of 4.1mm in X direction, 2.9mm in Y direction and 2.25mm in Z direction, our model achieves a precision of 0.01mm in X and Y directions and 0.015mm in Z direction. Comparison of our model with traditional pinhole camera model shows that two kinds of models have a similar reconstruction precision of X coordinates. However, traditional pinhole camera model has a lower precision of Y and Z coordinates than our model. The method proposed in this paper is very helpful for the micro-gripping system based on SLM microscopic vision. Copyright © 2016 Elsevier Ltd. All rights reserved.

Microscopic insight into the origin of enhanced glass-forming ability of metallic melts on micro-alloying

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, C. J.; Chathoth, S. M., E-mail: smavilac@cityu.edu.hk; Podlesnyak, A.

2015-09-28

Extensive efforts have been made to develop metallic-glasses with large casting diameter. Such efforts were hindered by the poor understanding of glass formation mechanisms and the origin of the glass-forming ability (GFA) in metallic glass-forming systems. In this work, we have investigated relaxation dynamics of a model bulk glass-forming alloy system that shows the enhanced at first and then diminished GFA on increasing the percentage of micro-alloying. The micro-alloying did not have any significant impact on the thermodynamic properties. The GFA increasing on micro-alloying in this system cannot be explained by the present theoretical knowledge. Our results indicate that atomicmore » caging is the primary factor that influences the GFA. The composition dependence of the atomic caging time or residence time is found to be well correlated with GFA of the system.« less

Microscopic insight into the origin of enhanced glass-forming ability of metallic melts on micro-alloying

DOE PAGES

Chen, C. J.; Podlesnyak, A.; Mamontov, E.; ...

2015-09-28

We've made extensive efforts to develop metallic-glasses with large casting diameter. Such efforts were hindered by the poor understanding of glass formation mechanisms and the origin of the glass-forming ability (GFA) in metallic glass-forming systems. We have investigated relaxation dynamics of a model bulk glass-forming alloy system that shows the enhanced at first and then diminished GFA on increasing the percentage of micro-alloying. The micro-alloying did not have any significant impact on the thermodynamic properties. The GFA increasing on micro-alloying in this system cannot be explained by the present theoretical knowledge. Finally, our results indicate that atomic caging is themore » primary factor that influences the GFA. The composition dependence of the atomic caging time or residence time is found to be well correlated with GFA of the system.« less

Pressure activated interconnection of micro transfer printed components

NASA Astrophysics Data System (ADS)

Prevatte, Carl; Guven, Ibrahim; Ghosal, Kanchan; Gomez, David; Moore, Tanya; Bonafede, Salvatore; Raymond, Brook; Trindade, António Jose; Fecioru, Alin; Kneeburg, David; Meitl, Matthew A.; Bower, Christopher A.

2016-05-01

Micro transfer printing and other forms of micro assembly deterministically produce heterogeneously integrated systems of miniaturized components on non-native substrates. Most micro assembled systems include electrical interconnections to the miniaturized components, typically accomplished by metal wires formed on the non-native substrate after the assembly operation. An alternative scheme establishing interconnections during the assembly operation is a cost-effective manufacturing method for producing heterogeneous microsystems, and facilitates the repair of integrated microsystems, such as displays, by ex post facto addition of components to correct defects after system-level tests. This letter describes pressure-concentrating conductor structures formed on silicon (1 0 0) wafers to establish connections to preexisting conductive traces on glass and plastic substrates during micro transfer printing with an elastomer stamp. The pressure concentrators penetrate a polymer layer to form the connection, and reflow of the polymer layer bonds the components securely to the target substrate. The experimental yield of series-connected test systems with >1000 electrical connections demonstrates the suitability of the process for manufacturing, and robustness of the test systems against exposure to thermal shock, damp heat, and mechanical flexure shows reliability of the resulting bonds.

Microfabricated ion frequency standard

DOEpatents

Schwindt, Peter; Biedermann, Grant; Blain, Matthew G.; Stick, Daniel L.; Serkland, Darwin K.; Olsson, III, Roy H.

2010-12-28

A microfabricated ion frequency standard (i.e. an ion clock) is disclosed with a permanently-sealed vacuum package containing a source of ytterbium (Yb) ions and an octupole ion trap. The source of Yb ions is a micro-hotplate which generates Yb atoms which are then ionized by a ultraviolet light-emitting diode or a field-emission electron source. The octupole ion trap, which confines the Yb ions, is formed from suspended electrodes on a number of stacked-up substrates. A microwave source excites a ground-state transition frequency of the Yb ions, with a frequency-doubled vertical-external-cavity laser (VECSEL) then exciting the Yb ions up to an excited state to produce fluorescent light which is used to tune the microwave source to the ground-state transition frequency, with the microwave source providing a precise frequency output for the ion clock.

Ultrasound for Drug and Gene Delivery to the Brain

PubMed Central

Hynynen, Kullervo

2008-01-01

Noninvasive, transient, and local image-guided blood-brain barrier disruption (BBBD) has been demonstrated with focused ultrasound exposure in animal models. Most studies have combined low pressure amplitude and low time average acoustic power burst sonications with intra-vascular injection of pre-formed micro-bubbles to produce BBBD without damage to the neurons. The BBB has been shown to be healed within a few hours after the exposure. The combination of focused ultrasound beams with MR image guidance allows precise anatomical targeting as demonstrated by the delivery of several marker molecules in different animal models. This method may in the future have a significant impact on the diagnosis and treatment of central nervous system (CNS) disorders. Most notably, the delivery of the chemotherapy agents liposomal Doxorubicin and Herceptin has been shown in a rat model. PMID:18486271

Microfabricated instrument for tissue biopsy and analysis

DOEpatents

Krulevitch, Peter A.; Lee, Abraham P.; Northrup, M. Allen; Benett, William J.

2001-01-01

A microfabricated biopsy/histology instrument which has several advantages over the conventional procedures, including minimal specimen handling, smooth cutting edges with atomic sharpness capable of slicing very thin specimens (approximately 2 .mu.m or greater), micro-liter volumes of chemicals for treating the specimens, low cost, disposable, fabrication process which renders sterile parts, and ease of use. The cutter is a "cheese-grater" style design comprising a block or substrate of silicon and which uses anisotropic etching of the silicon to form extremely sharp and precise cutting edges. As a specimen is cut, it passes through the silicon cutter and lies flat on a piece of glass which is bonded to the cutter. Microchannels are etched into the glass or silicon substrates for delivering small volumes of chemicals for treating the specimen. After treatment, the specimens can be examined through the glass substrate.

Piezoresistive microcantilever based lab-on-a-chip system for detection of macronutrients in the soil

NASA Astrophysics Data System (ADS)

Patkar, Rajul S.; Ashwin, Mamta; Rao, V. Ramgopal

2017-12-01

Monitoring of soil nutrients is very important in precision agriculture. In this paper, we have demonstrated a micro electro mechanical system based lab-on-a-chip system for detection of various soil macronutrients which are available in ionic form K+, NO3-, and H2PO4-. These sensors are highly sensitive piezoresistive silicon microcantilevers coated with a polymer matrix containing methyltridodecylammonium nitrate ionophore/ nitrate ionophore VI for nitrate sensing, 18-crown-6 ether for potassium sensing and Tributyltin chloride for phosphate detection. A complete lab-on-a-chip system integrating a highly sensitive current excited Wheatstone's bridge based portable electronic setup along with arrays of microcantilever devices mounted on a printed circuit board with a liquid flow cell for on the site experimentation for soil test has been demonstrated.

Supercomputing on massively parallel bit-serial architectures

NASA Technical Reports Server (NTRS)

Iobst, Ken

1985-01-01

Research on the Goodyear Massively Parallel Processor (MPP) suggests that high-level parallel languages are practical and can be designed with powerful new semantics that allow algorithms to be efficiently mapped to the real machines. For the MPP these semantics include parallel/associative array selection for both dense and sparse matrices, variable precision arithmetic to trade accuracy for speed, micro-pipelined train broadcast, and conditional branching at the processing element (PE) control unit level. The preliminary design of a FORTRAN-like parallel language for the MPP has been completed and is being used to write programs to perform sparse matrix array selection, min/max search, matrix multiplication, Gaussian elimination on single bit arrays and other generic algorithms. A description is given of the MPP design. Features of the system and its operation are illustrated in the form of charts and diagrams.

Si Isotopes in Enstatite Chondrites: Implications to Accretion and Differentiation Event of the Earth

NASA Astrophysics Data System (ADS)

Sikdar, J.; Rai, V. K.

2018-05-01

The abstract summarizes the recent results on high precision Si isotope analyses in various micro milled components of Enstatite chondrites with implications towards the accretion and primary differentiation event of the Earth.

Peptostreptococcus micros in primary endodontic infections as detected by 16S rDNA-based polymerase chain reaction.

PubMed

Siqueira, José F; Rôças, Isabela N; Andrade, Arnaldo F B; de Uzeda, Milton

2003-02-01

A 16S rDNA-based polymerase chain reaction (PCR) method was used to detect Peptostreptococcus micros in primary root canal infections. Samples were collected from 50 teeth having carious lesions, necrotic pulps, and different forms of periradicular diseases. DNA extracted from the samples was amplified using the PCR assay, which yielded a specific fragment of P. micros 16S rDNA. P. micros was detected in 6 of 22 root canals associated with asymptomatic chronic periradicular lesions (27.3%), 2 of 8 teeth with acute apical periodontitis (25%), and 6 of 20 cases of acute periradicular abscess (30%). In general, P. micros was found in 14 of 50 cases (28%). There was no correlation between the presence of P. micros and the occurrence of symptoms. Findings suggested that P. micros can be involved in the pathogenesis of different forms of periradicular lesions.

Angular dependant micro-ESR characterization of a locally doped Gd3+:Al2O3 hybrid system for quantum applications

NASA Astrophysics Data System (ADS)

Wisby, I. S.; de Graaf, S. E.; Gwilliam, R.; Adamyan, A.; Kubatkin, S. E.; Meeson, P. J.; Tzalenchuk, A. Ya.; Lindstrom, T.

Rare-earth doped crystals interfaced with superconducting quantum circuitry are an attractive platform for quantum memory and transducer applications. Here we present a detailed characterization of a locally implanted Gd3+ in Al2O3 system coupled to a superconducting micro-resonator, by performing angular dependent micro-electron-spin-resonance (micro-ESR) measurements at mK temperatures. The device is fabricated using a hard Si3N4 mask to facilitate a local ion-implantation technique for precision control of the dopant location. The technique is found not to degrade the internal quality factor of the resonators which remains above 105 (1). We find the measured angular dependence of the micro-ESR spectra to be in excellent agreement with the modelled Hamiltonian, supporting the conclusion that the dopant ions are successfully integrated into their relevant lattice sites whilst maintaining crystalline symmetries. Furthermore, we observe clear contributions from individual microwave field components of our micro-resonator, emphasising the need for controllable local implantation. 1 Wisby et al. Appl. Phys. Lett. 105, 102601 (2014)

Self-gauged fiber-optic micro-heater with an operation temperature above 1000°C.

PubMed

Liu, Guigen; Sheng, Qiwen; Dam, Dustin; Hua, Jiong; Hou, Weilin; Han, Ming

2017-04-01

We report a fiber-optic micro-heater based on a miniature crystalline silicon Fabry-Perot interferometer (FPI) fusion spliced to the endface of a single-mode fiber. The silicon FPI, having a diameter of 100 μm and a length of 10 or 200 μm, is heated by a 980 nm laser diode guided through the lead-in fiber, leading to a localized hot spot with a temperature that can be conveniently tuned from the ambient temperature to >1000°C in air. In the meantime, using a white light system operating in the 1550 nm wavelength window where the silicon is transparent, the silicon FPI itself also serves as a thermometer with high resolution and high speed for convenient monitoring and precise control of the heater temperature. Due to its small size, high temperature capability, and easy operation, the micro-heater is attractive for applications in a variety of fields, such as biology, microfluidics system, mechanical engineering, and high-temperature optical sensing. As an example, the application of this micro-heater as a micro-boiler and micro-bubble generator has been demonstrated.

Forensic microradiology: micro-computed tomography (Micro-CT) and analysis of patterned injuries inside of bone.

PubMed

Thali, Michael J; Taubenreuther, Ulrike; Karolczak, Marek; Braun, Marcel; Brueschweiler, Walter; Kalender, Willi A; Dirnhofer, Richard

2003-11-01

When a knife is stabbed in bone, it leaves an impression in the bone. The characteristics (shape, size, etc.) may indicate the type of tool used to produce the patterned injury in bone. Until now it has been impossible in forensic sciences to document such damage precisely and non-destructively. Micro-computed tomography (Micro-CT) offers an opportunity to analyze patterned injuries of tool marks made in bone. Using high-resolution Micro-CT and computer software, detailed analysis of three-dimensional (3D) architecture has recently become feasible and allows microstructural 3D bone information to be collected. With adequate viewing software, data from 2D slice of an arbitrary plane can be extracted from 3D datasets. Using such software as a "digital virtual knife," the examiner can interactively section and analyze the 3D sample. Analysis of the bone injury revealed that Micro-CT provides an opportunity to correlate a bone injury to an injury-causing instrument. Even broken knife tips can be graphically and non-destructively assigned to a suspect weapon.

Superhydrophobic surface prepared by micro-milling and WEDM on aluminum alloy

NASA Astrophysics Data System (ADS)

Yanling, Wan; Jian, Yang; Huadong, Yu

2018-06-01

To simulate the hydrophobic microstructure of rice leaf surface, high-speed precision micro-milling machine was used to fabricate micro groove array structure on the surface of aluminum alloy. The micro-and nanostructure was constructed on the surface of the grooved convex platform by Wire Cut Electrical Discharge Machining (WEDM). The surface morphology and hydrophobic properties of the aluminum alloy microstructures fabricated by two processing methods were observed respectively, and the hydrophobic mechanism was analyzed. The results show that the contact angle was effectively improved from 49° up to 158.4° in the vertical direction, and 146.7° in the parallel direction. The change of surface wettability from hydrophilic to hydrophobic was realized. By comparison, the micro-and nanostructure fabricated by WEDM had improved the hydrophobic stability of the aluminum alloy surface while enlarging the contact Angle, and the micro-milling groove structure further amplified the contact angle and greatly reduced the contact area of the water droplet, it was also observed that the drop took longer to completely spread on the sample after WEDM.

High-precision micro-displacement optical-fiber sensor based on surface plasmon resonance.

PubMed

Zhu, Zongda; Liu, Lu; Liu, Zhihai; Zhang, Yu; Zhang, Yaxun

2017-05-15

We propose and demonstrate a novel optical-fiber micro-displacement sensor based on surface plasmon resonance (SPR) by fabricating a Kretschmann configuration on graded-index multimode fiber (GIMMF). We employ a single-mode fiber to change the radial position of the incident beam as the displacement. In the GIMMF, the angle between the light beam and fiber axis, which is closely related to the resonance angle, is changed by the displacement; thus, the resonance wavelength of the fiber SPR shifts. This micro-displacement fiber sensor has a wide detection range of 0-25 μm, a high sensitivity with maximum up to 10.32 nm/μm, and a nanometer resolution with minimum to 2 nm, which transcends almost all of other optical-fiber micro-displacement sensors. In addition, we also research that increasing the fiber polishing angle or medium refractive index can improve the sensitivity. This micro-displacement sensor will have a great significance in many industrial applications and provide a neoteric, rapid, and accurate optical measurement method in micro-displacement.

Biomarker MicroRNAs for Diagnosis of Oral Squamous Cell Carcinoma Identified Based on Gene Expression Data and MicroRNA-mRNA Network Analysis

PubMed Central

Zhang, Hui; Li, Tangxin; Zheng, Linqing

2017-01-01

Oral squamous cell carcinoma is one of the most malignant tumors with high mortality rate worldwide. Biomarker discovery is critical for early diagnosis and precision treatment of this disease. MicroRNAs are small noncoding RNA molecules which often regulate essential biological processes and are good candidates for biomarkers. By integrative analysis of both the cancer-associated gene expression data and microRNA-mRNA network, miR-148b-3p, miR-629-3p, miR-27a-3p, and miR-142-3p were screened as novel diagnostic biomarkers for oral squamous cell carcinoma based on their unique regulatory abilities in the network structure of the conditional microRNA-mRNA network and their important functions. These findings were confirmed by literature verification and functional enrichment analysis. Future experimental validation is expected for the further investigation of their molecular mechanisms. PMID:29098014

Optimal micro-mirror tilt angle and sync mark design for digital micro-mirror device based collinear holographic data storage system.

PubMed

Liu, Jinpeng; Horimai, Hideyoshi; Lin, Xiao; Liu, Jinyan; Huang, Yong; Tan, Xiaodi

2017-06-01

The collinear holographic data storage system (CHDSS) is a very promising storage system due to its large storage capacities and high transfer rates in the era of big data. The digital micro-mirror device (DMD) as a spatial light modulator is the key device of the CHDSS due to its high speed, high precision, and broadband working range. To improve the system stability and performance, an optimal micro-mirror tilt angle was theoretically calculated and experimentally confirmed by analyzing the relationship between the tilt angle of the micro-mirror on the DMD and the power profiles of diffraction patterns of the DMD at the Fourier plane. In addition, we proposed a novel chess board sync mark design in the data page to reduce the system bit error rate in circumstances of reduced aperture required to decrease noise and median exposure amount. It will provide practical guidance for future DMD based CHDSS development.

Structural coloration of metallic surfaces with micro/nano-structures induced by elliptical vibration texturing

NASA Astrophysics Data System (ADS)

Yang, Yang; Pan, Yayue; Guo, Ping

2017-04-01

Creating orderly periodic micro/nano-structures on metallic surfaces, or structural coloration, for control of surface apparent color and optical reflectivity has been an exciting research topic over the years. The direct applications of structural coloration include color marking, display devices, and invisibility cloak. This paper presents an efficient method to colorize metallic surfaces with periodic micro/nano-gratings using elliptical vibration texturing. When the tool vibration is coupled with a constant cutting velocity, controlled periodic ripples can be generated due to the overlapping tool trajectory. These periodic ripples with a wavelength near visible spectrum can act as micro-gratings to introduce iridescent colors. The proposed technique also provides a flexible method for color marking of metallic surfaces with arbitrary patterns and images by precise control of the spacing distance and orientation of induced micro/nano-ripples. Theoretical analysis and experimental results are given to demonstrate structural coloration of metals by a direct mechanical machining technique.

Construction and quality assurance of large area resistive strip Micromegas for the upgrade of the ATLAS Muon Spectrometer at LHC/CERN

NASA Astrophysics Data System (ADS)

Lösel, P.

2017-06-01

Large area Micromegas detectors will be employed for the first time in high-energy physics experiments. To cope with increasing background rates, associated with the steadily increasing luminosity of LHC to 10 times design luminosity, the present detector technology in the current innermost stations of the muon endcap system of the ATLAS experiment (the Small Wheel), will be replaced in 2019/2020 by resistive strip Micromegas and small strip TGC detectors. Both technologies will provide tracking and trigger information. In the "New Small Wheel" the Micromegas will be arranged in eight detection layers built of trapezoidally shaped quadruplets of four different sizes covering in total about 1200 m2 of detection plane. In order to achieve 15 % transverse momentum resolution for 1 TeV muons, a challenging mechanical precision is required in the construction of each active plane, with an alignment of the readout strips at the level of 30 μm RMS along the precision coordinate and 80 μm RMS perpendicular to the plane. Each individual Micromegas plane must achieve a spatial resolution better than 100 μm at background rates up to 15 kHz/cm2 while being operated in an inhomogeneous magnetic field (B <= 0.3 T). The required mechanical precision for the production of the components and their assembly, on such large area detectors, is a key point and must be controlled during construction and integration. Particularly the alignment of the readout strips within a quadruplet appears to be demanding. The readout strips are etched on PCB boards using photolithographic processes. Depending on the type of the module, 3 or 5 PCB boards need to be joined and precisely aligned to form a full readout plane. The precision in the alignment is reached either by use of precision mechanical holes or by optical masks, both referenced to the strip patterns. Assembly procedures have been developed to build the single panels with the required mechanical precision and to assemble them in a module including the four metallic micro-meshes. Methods to confirm the precision of components and assembly are based on precise optical devices and X-ray or cosmic muon investigations. We will report on the construction procedures for the Micromegas quadruplets, on the quality control procedures and results, and on the assembly and calibration methods.

Micro-PIXE analysis of silicate reference standards

USGS Publications Warehouse

Czamanske, G.K.; Sisson, T.W.; Campbell, J.L.; Teesdale, W.J.

1993-01-01

The accuracy and precision of the University of Guelph proton microprobe have been evaluated through trace-element analysis of well-characterized silicate glasses and minerals, including BHVO-1 glass, Kakanui augite and hornblende, and ten other natural samples of volcanic glass, amphibole, pyroxene, and garnet. Using the 2.39 wt% Mo in a NIST steel as the standard, excellent precision and agreement between reported and analyzed abundances were obtained for Fe, Ni, Cu, Zn, Ga, Rb, Sr, Y, Zr, and Nb. -from Authors

Three dimensional morphological studies of Larger Benthic Foraminifera at the population level using micro computed tomography

NASA Astrophysics Data System (ADS)

Kinoshita, Shunichi; Eder, Wolfgang; Woeger, Julia; Hohenegger, Johann; Briguglio, Antonino; Ferrandez-Canadell, Carles

2015-04-01

Symbiont-bearing larger benthic Foraminifera (LBF) are long-living marine (at least 1 year), single-celled organisms with complex calcium carbonate shells. Their morphology has been intensively studied since the middle of the nineteenth century. This led to a broad spectrum of taxonomic results, important from biostratigraphy to ecology in shallow water tropical to warm temperate marine palaeo-environments. However, it was necessary for the traditional investigation methods to cut or destruct specimens for analysing the taxonomically important inner structures. X-ray micro-computed tomography (microCT) is one of the newest techniques used in morphological studies. The greatest advantage is the non-destructive acquisition of inner structures. Furthermore, the running improve of microCT scanners' hard- and software provides high resolution and short time scans well-suited for LBF. Three-dimensional imaging techniques allow to select and extract each chamber and to measure easily its volume, surface and several form parameters used for morphometric analyses. Thus, 3-dimensional visualisation of LBF-tests is a very big step forward from traditional morphology based on 2-dimensional data. The quantification of chamber form is a great opportunity to tackle LBF structures, architectures and the bauplan geometry. The micrometric digital resolution is the only way to solve many controversies in phylogeny and evolutionary trends of LBF. For the present study we used micro-computed tomography to easily investigate the chamber number of every specimen from statistically representative part of populations to estimate population dynamics. Samples of living individuals are collected at monthly intervals from fixed locations. Specific preparation allows to scan up to 35 specimens per scan within 2 hours and to obtain the complete digital dataset for each specimen of the population. MicroCT enables thus a fast and precise count of all chambers built by the foraminifer from its birth until the time of collection and to extract selected chambers for further studies. The variation in chamber number during the sampling period (in this study limited at 15 months) will allow the estimation of the mean chamber building rate for each investigated species. However, a number of morphological aberrations within the population can be observed: often multiple proloculi are present; their orientation to the equatorial plane (or planes) respectively the spatial position of the foramina between proloculus (or proloculi) to the reniform deuteroloculi, the geometry of septa and septula and their variation trough ontogeny and several other ontogenetic variation need further attention. Many new insights into the biology of living and fossil LBF will be obtained when the three dimensional morphology of the complete foraminiferal shell is raised to the population level.

MicroRNA Detection Using a Double Molecular Beacon Approach: Distinguishing Between miRNA and Pre-miRNA.

PubMed

James, Amanda Marie; Baker, Meredith B; Bao, Gang; Searles, Charles D

2017-01-01

MicroRNAs (miRNAs) are small, noncoding RNAs that post-transcriptionally regulate gene expression and are recognized for their roles both as modulators of disease progression and as biomarkers of disease activity, including neurological diseases, cancer, and cardiovascular disease (CVD). Commonly, miRNA abundance is assessed using quantitative real-time PCR (qRT-PCR), however, qRT-PCR for miRNA can be labor intensive, time consuming, and may lack specificity for detection of mature versus precursor forms of miRNA. Here, we describe a novel double molecular beacon approach to miRNA assessment that can distinguish and quantify mature versus precursor forms of miRNA in a single assay, an essential feature for use of miRNAs as biomarkers for disease. Using this approach, we found that molecular beacons with DNA or combined locked nucleic acid (LNA)-DNA backbones can detect mature and precursor miRNAs (pre-miRNAs) of low (< 1 nM) abundance in vitro . The double molecular beacon assay was accurate in assessing miRNA abundance in a sample containing a mixed population of mature and precursor miRNAs. In contrast, qRT-PCR and the single molecular beacon assay overestimated miRNA abundance. Additionally, the double molecular beacon assay was less labor intensive than traditional qRT-PCR and had 10-25% increased specificity. Our data suggest that the double molecular beacon-based approach is more precise and specific than previous methods, and has the promise of being the standard for assessing miRNA levels in biological samples.

MicroRNA Detection Using a Double Molecular Beacon Approach: Distinguishing Between miRNA and Pre-miRNA

PubMed Central

James, Amanda Marie; Baker, Meredith B.; Bao, Gang; Searles, Charles D.

2017-01-01

MicroRNAs (miRNAs) are small, noncoding RNAs that post-transcriptionally regulate gene expression and are recognized for their roles both as modulators of disease progression and as biomarkers of disease activity, including neurological diseases, cancer, and cardiovascular disease (CVD). Commonly, miRNA abundance is assessed using quantitative real-time PCR (qRT-PCR), however, qRT-PCR for miRNA can be labor intensive, time consuming, and may lack specificity for detection of mature versus precursor forms of miRNA. Here, we describe a novel double molecular beacon approach to miRNA assessment that can distinguish and quantify mature versus precursor forms of miRNA in a single assay, an essential feature for use of miRNAs as biomarkers for disease. Using this approach, we found that molecular beacons with DNA or combined locked nucleic acid (LNA)-DNA backbones can detect mature and precursor miRNAs (pre-miRNAs) of low (< 1 nM) abundance in vitro. The double molecular beacon assay was accurate in assessing miRNA abundance in a sample containing a mixed population of mature and precursor miRNAs. In contrast, qRT-PCR and the single molecular beacon assay overestimated miRNA abundance. Additionally, the double molecular beacon assay was less labor intensive than traditional qRT-PCR and had 10-25% increased specificity. Our data suggest that the double molecular beacon-based approach is more precise and specific than previous methods, and has the promise of being the standard for assessing miRNA levels in biological samples. PMID:28255356

Directly driven source of multi-gigahertz, sub-picosecond optical pulses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Messerly, Michael J.; Dawson, Jay W.; Barty, Christopher P.J.

2015-10-20

A robust, compact optical pulse train source is described, with the capability of generating sub-picosecond micro-pulse sequences, which can be periodic as well as non-periodic, and at repetition rates tunable over decades of baseline frequencies, from MHz to multi-GHz regimes. The micro-pulses can be precisely controlled and formatted to be in the range of many ps in duration to as short as several fs in duration. The system output can be comprised of a continuous wave train of optical micro-pulses or can be programmed to provide gated bursts of macro-pulses, with each macro-pulse consisting of a specific number of micro-pulsesmore » or a single pulse picked from the higher frequency train at a repetition rate lower than the baseline frequency. These pulses could then be amplified in energy anywhere from the nJ to MJ range.« less

microRNA expression in the neural retina: Focus on Müller glia.

PubMed

Quintero, Heberto; Lamas, Mónica

2018-03-01

The neural retina hosts a unique specialized type of macroglial cell that not only preserves retinal homeostasis, function, and integrity but also may serve as a source of new neurons during regenerative processes: the Müller cell. Precise microRNA-driven mechanisms of gene regulation impel and direct the processes of Müller glia lineage acquisition from retinal progenitors during development, the triggering of their response to retinal degeneration and, in some cases, Müller cell reprogramming and regenerative events. In this review we survey the recent reports describing, through functional assays, the regulatory role of microRNAs in Müller cell physiology, differentiation potential, and retinal pathology. We discuss also the evidence based on expression analysis that points out the relevance of a Müller glia-specific microRNA signature that would orchestrate these processes. © 2017 Wiley Periodicals, Inc.

Chemical characterization of single micro- and nano-particles by optical catapulting-optical trapping-laser-induced breakdown spectroscopy

NASA Astrophysics Data System (ADS)

Fortes, Francisco J.; Fernández-Bravo, Angel; Javier Laserna, J.

2014-10-01

Spectral identification of individual micro- and nano-sized particles by the sequential intervention of optical catapulting, optical trapping and laser-induced breakdown spectroscopy is presented. The three techniques are used for different purposes. Optical catapulting (OC) serves to put the particulate material under inspection in aerosol form. Optical trapping (OT) permits the isolation and manipulation of individual particles from the aerosol, which are subsequently analyzed by laser-induced breakdown spectroscopy (LIBS). Once catapulted, the dynamics of particle trapping depends both on the laser beam characteristics (power and intensity gradient) and on the particle properties (size, mass and shape). Particles are stably trapped in air at atmospheric pressure and can be conveniently manipulated for a precise positioning for LIBS analysis. The spectra acquired from the individually trapped particles permit a straightforward identification of the material inspected. Variability of LIBS signal for the inspection of Ni microspheres was 30% relative standard deviation. OC-OT-LIBS permits the separation of particles in a heterogeneous mixture and the subsequent analysis of the isolated particle of interest. In order to evaluate the sensitivity of the approach, the number of absolute photons emitted by a single trapped particle was calculated. The limit of detection (LOD) for Al2O3 particles was calculated to be 200 attograms aluminium.

From Biological Cilia to Artificial Flow Sensors: Biomimetic Soft Polymer Nanosensors with High Sensing Performance

PubMed Central

Asadnia, Mohsen; Kottapalli, Ajay Giri Prakash; Karavitaki, K. Domenica; Warkiani, Majid Ebrahimi; Miao, Jianmin; Corey, David P.; Triantafyllou, Michael

2016-01-01

We report the development of a new class of miniature all-polymer flow sensors that closely mimic the intricate morphology of the mechanosensory ciliary bundles in biological hair cells. An artificial ciliary bundle is achieved by fabricating bundled polydimethylsiloxane (PDMS) micro-pillars with graded heights and electrospinning polyvinylidenefluoride (PVDF) piezoelectric nanofiber tip links. The piezoelectric nature of a single nanofiber tip link is confirmed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Rheology and nanoindentation experiments are used to ensure that the viscous properties of the hyaluronic acid (HA)-based hydrogel are close to the biological cupula. A dome-shaped HA hydrogel cupula that encapsulates the artificial hair cell bundle is formed through precision drop-casting and swelling processes. Fluid drag force actuates the hydrogel cupula and deflects the micro-pillar bundle, stretching the nanofibers and generating electric charges. Functioning with principles analogous to the hair bundles, the sensors achieve a sensitivity and threshold detection limit of 300 mV/(m/s) and 8 μm/s, respectively. These self-powered, sensitive, flexible, biocompatibale and miniaturized sensors can find extensive applications in navigation and maneuvering of underwater robots, artificial hearing systems, biomedical and microfluidic devices. PMID:27622466

Rapid and automated enumeration of viable bacteria in compost using a micro-colony auto counting system.

PubMed

Wang, Xiaodan; Yamaguchi, Nobuyasu; Someya, Takashi; Nasu, Masao

2007-10-01

The micro-colony method was used to enumerate viable bacteria in composts. Cells were vacuum-filtered onto polycarbonate filters and incubated for 18 h on LB medium at 37 degrees C. Bacteria on the filters were stained with SYBR Green II, and enumerated using a newly developed micro-colony auto counting system which can automatically count micro-colonies on half the area of the filter within 90 s. A large number of bacteria in samples retained physiological activity and formed micro-colonies within 18 h, whereas most could not form large colonies on conventional media within 1 week. The results showed that this convenient technique can enumerate viable bacteria in compost rapidly for its efficient quality control.

Precise replication of antireflective nanostructures from biotemplates

NASA Astrophysics Data System (ADS)

Gao, Hongjun; Liu, Zhongfan; Zhang, Jin; Zhang, Guoming; Xie, Guoyong

2007-03-01

The authors report herein a new type of nanonipple structures on the cicada's eye and the direct structural replication of the complex micro- and nanostructures for potential functional emulation. A two-step direct molding process is developed to replicate these natural micro- and nanostructures using epoxy resin with high fidelity, which demonstrates a general way of fabricating functional nanostructures by direct replication of natural biotemplates via a suitable physicochemical process. Measurements of spectral reflectance showed that this kind of replicated nanostructure has remarkable antireflective property, suggestive of its potential applications to optical devices.

Study on micro fabricated stainless steel surface to anti-biofouling using electrochemical fabrication

NASA Astrophysics Data System (ADS)

Hwang, Byeong Jun; Lee, Sung Ho

2017-12-01

Biofilm formed on the surface of the object by the microorganism resulting in fouling organisms. This has led to many problems in daily life, medicine, health and industrial community. In this study, we tried to prevent biofilm formation on the stainless steel (SS304) sheet surface with micro fabricated structure. After then forming the microscale colloid patterns on the surface of stainless steel by using an electrochemical etching forming a pattern by using a FeCl3 etching was further increase the surface roughness. Culturing the Pseudomonas aeruginosa on the stainless steel fabricated with a micro structure on the surface was observed a relationship between the surface roughness and the biological fouling of the micro structure. As a result, the stainless steel surface with a micro structure was confirmed to be the biological fouling occurs less. We expect to be able to solve the problems caused by biological fouling in various fields such as medicine, engineering, using this research.

Nanorobotic System iTRo for Controllable 1D Micro/nano Material Twisting Test.

PubMed

Lu, Haojian; Shang, Wanfeng; Wei, Xueyong; Yang, Zhan; Fukuda, Toshio; Shen, Yajing

2017-06-08

In-situ micro/nano characterization is an indispensable methodology for material research. However, the precise in-situ SEM twisting of 1D material with large range is still challenge for current techniques, mainly due to the testing device's large size and the misalignment between specimen and the rotation axis. Herein, we propose an in-situ twist test robot (iTRo) to address the above challenges and realize the precise in-situ SEM twisting test for the first time. Firstly, we developed the iTRo and designed a series of control strategies, including assembly error initialization, triple-image alignment (TIA) method for rotation axis alignment, deformation-based contact detection (DCD) method for sample assembly, and switch control for robots cooperation. After that, we chose three typical 1D material, i.e., magnetic microwire Fe 74 B 13 Si 11 C 2 , glass fiber, and human hair, for twisting test and characterized their properties. The results showed that our approach is able to align the sample to the twisting axis accurately, and it can provide large twisting range, heavy load and high controllability. This work fills the blank of current in-situ mechanical characterization methodologies, which is expected to give significant impact in the fundamental nanomaterial research and practical micro/nano characterization.

New concepts and materials for the manufacturing of MR-compatible guide wires.

PubMed

Brecher, Christian; Emonts, Michael; Brack, Alexander; Wasiak, Christian; Schütte, Adrian; Krämer, Nils; Bruhn, Robin

2014-04-01

This paper shows the development of a new magnetic resonance imaging (MRI)-compatible guide wire made from fiber-reinforced plastics. The basic material of the developed guide wire is manufactured using a specially developed micro-pullwinding technology, which allows the adjustment of tensile, bending, and torsional stiffness independent from each other. Additionally, the micro-pullwinding technology provides the possibility to vary the stiffness along the length of the guide wire in a continuous process. With the possibilities of this technology, the mechanical properties of the guide wire were precisely adjusted for the intended usage in MRI-guided interventions. The performance of the guide wire regarding the mechanical properties was investigated. It could be shown, that the mechanical properties could be changed independently from each other by varying the process parameters. Especially, the torsional stiffness could be significantly improved with only a minor influence on bending and tensile properties. The precise influence of the variation of the winding angle on the mechanical and geometrical properties has to be further investigated. The usability of the guide wire as well as its visibility in MRI was investigated by radiologists. With the micro-pullwinding technology, a continuous manufacturing technique for highly stressable, MRI-safe profiles is available and can be the trigger for a new class of medical devices.

Space Technology 7 Disturbance Reduction System - precision control flight Validation

NASA Technical Reports Server (NTRS)

Carmain, Andrew J.; Dunn, Charles; Folkner, William; Hruby, Vlad; Spence, Doug; O'Donnell, James; Markley, Landis; Maghami, Peiman; Hsu, Oscar; Demmons, N.;

Estimation of genetic variance for macro- and micro-environmental sensitivity using double hierarchical generalized linear models

PubMed Central

2013-01-01

Background Genetic variation for environmental sensitivity indicates that animals are genetically different in their response to environmental factors. Environmental factors are either identifiable (e.g. temperature) and called macro-environmental or unknown and called micro-environmental. The objectives of this study were to develop a statistical method to estimate genetic parameters for macro- and micro-environmental sensitivities simultaneously, to investigate bias and precision of resulting estimates of genetic parameters and to develop and evaluate use of Akaike’s information criterion using h-likelihood to select the best fitting model. Methods We assumed that genetic variation in macro- and micro-environmental sensitivities is expressed as genetic variance in the slope of a linear reaction norm and environmental variance, respectively. A reaction norm model to estimate genetic variance for macro-environmental sensitivity was combined with a structural model for residual variance to estimate genetic variance for micro-environmental sensitivity using a double hierarchical generalized linear model in ASReml. Akaike’s information criterion was constructed as model selection criterion using approximated h-likelihood. Populations of sires with large half-sib offspring groups were simulated to investigate bias and precision of estimated genetic parameters. Results Designs with 100 sires, each with at least 100 offspring, are required to have standard deviations of estimated variances lower than 50% of the true value. When the number of offspring increased, standard deviations of estimates across replicates decreased substantially, especially for genetic variances of macro- and micro-environmental sensitivities. Standard deviations of estimated genetic correlations across replicates were quite large (between 0.1 and 0.4), especially when sires had few offspring. Practically, no bias was observed for estimates of any of the parameters. Using Akaike’s information criterion the true genetic model was selected as the best statistical model in at least 90% of 100 replicates when the number of offspring per sire was 100. Application of the model to lactation milk yield in dairy cattle showed that genetic variance for micro- and macro-environmental sensitivities existed. Conclusion The algorithm and model selection criterion presented here can contribute to better understand genetic control of macro- and micro-environmental sensitivities. Designs or datasets should have at least 100 sires each with 100 offspring. PMID:23827014

Inertial drives for micro- and nanorobots: two novel mechanisms

NASA Astrophysics Data System (ADS)

Zesch, Wolfgang; Buechi, Roland; Codourey, Alain; Siegwart, Roland Y.

1995-12-01

In micro or nanorobotics, high precision movement in two or more degrees of freedom is one of the main problems. Firstly, the positional precision has to be increased (< 10 nm) as the object sizes decrease. On the other hand, the workspace has to have macroscopic dimensions (1 cm3) to give high maneuverability to the system and to allow suitable handling at the micro/macro-world interface. As basic driving mechanisms for the ETHZ Nanorobot Project, two new piezoelectric devices have been developed. `Abalone' is a 3-dof system that relies on the impact drive principle. The 38 mm X 33 mm X 9 mm slider can be moved to each position and orientation in a horizontal plane within a theoretically infinite workspace. In the stepping mode it achieves a speed of 1 mm/s in translation and 7 deg/s in rotation. Within the actuator's local range of 6 micrometers fine positioning is possible with a resolution better than 10 nm. `NanoCrab' is a bearingless rotational micromotor relying on the stick-slip effect. This 10 mm X 7 mm X 7 mm motor has the advantage of a relatively high torque at low rotational speed and an excellent runout. While the maximum velocity is 60 rpm, it reaches its highest torque of 0.3 mNm at 2 rpm. Another benefit is the powerless holding torque of 0.9 mNm. With a typical step of 0.1 mrad and a local resolution 3 orders of magnitude better than the step angle, NanoCrab can be very precisely adjusted. Design and measurements of the characteristics of these two mechanisms will be presented and compared with the theoretical analysis of inertial drives presented in a companion paper. Finally their integration into the Nanorobot system will be discussed.

Precise Quantitation of MicroRNA in a Single Cell with Droplet Digital PCR Based on Ligation Reaction.

PubMed

Tian, Hui; Sun, Yuanyuan; Liu, Chenghui; Duan, Xinrui; Tang, Wei; Li, Zhengping

2016-12-06

MicroRNA (miRNA) analysis in a single cell is extremely important because it allows deep understanding of the exact correlation between the miRNAs and cell functions. Herein, we wish to report a highly sensitive and precisely quantitative assay for miRNA detection based on ligation-based droplet digital polymerase chain reaction (ddPCR), which permits the quantitation of miRNA in a single cell. In this ligation-based ddPCR assay, two target-specific oligonucleotide probes can be simply designed to be complementary to the half-sequence of the target miRNA, respectively, which avoids the sophisticated design of reverse transcription and provides high specificity to discriminate a single-base difference among miRNAs with simple operations. After the miRNA-templated ligation, the ddPCR partitions individual ligated products into a water-in-oil droplet and digitally counts the fluorescence-positive and negative droplets after PCR amplification for quantification of the target molecules, which possesses the power of precise quantitation and robustness to variation in PCR efficiency. By integrating the advantages of the precise quantification of ddPCR and the simplicity of the ligation-based PCR, the proposed method can sensitively measure let-7a miRNA with a detection limit of 20 aM (12 copies per microliter), and even a single-base difference can be discriminated in let-7 family members. More importantly, due to its high selectivity and sensitivity, the proposed method can achieve precise quantitation of miRNAs in single-cell lysate. Therefore, the ligation-based ddPCR assay may serve as a useful tool to exactly reveal the miRNAs' actions in a single cell, which is of great importance for the study of miRNAs' biofunction as well as for the related biomedical studies.

Breakthrough: micro-electronic photovoltaics

ScienceCinema

Okandan, Murat; Gupta, Vipin

2018-01-16

Sandia developed tiny glitter-sized photovoltaic (PV) cells that could revolutionize solar energy collection. The crystalline silicon micro-PV cells will be cheaper and have greater efficiencies than current PV collectors. Micro-PV cells require relatively little material to form well-controlled, highly efficient devices. Cell fabrication uses common microelectric and micro-electromechanical systems (MEMS) techniques.

Nanowall formation by maskless wet-etching on a femtosecond laser irradiated silicon surface

NASA Astrophysics Data System (ADS)

Lee, Siwoo; Jo, Kukhyun; Keum, Hee-sung; Chae, Sangmin; Kim, Yonghyeon; Choi, Jiyeon; Lee, Hyun Hwi; Kim, Hyo Jung

2018-04-01

We found that micro-cells surrounded by nanowalls can be formed by a maskless wet-etching process on Si (100) surfaces possessing Laser Induced Periodic Surface Structure (LIPSS) by femtosecond laser irradiation. The LIPSS process could produce periodic one-dimensional micron scale ripples on a Si surface, which could be developed into micro-cells by a subsequent etching process. The solution etching conditions strongly affected both the micro-cell and nanowall shapes such as the height and the thickness of nanowalls. The tetramethylammonium hydroxide solution created thin nanowalls and the resulting micro-cells with a well-flattened bottom while the KOH solution formed thick walls and incomplete micro-cells. The bottoms of micro-cells surrounded by the nanowalls were considerably flat with a 3.10 nm surface roughness. A pentacene layer was deposited on the micro-cells of a Si surface to evaluate the film properties by grazing incidence wide angle x-ray scattering measurements. The pentacene film on the micro-cell Si surface showed a strong film phase, which was comparable to the film phase grown on the atomically flat Si surface.

Precision Timing with shower maximum detectors based on pixelated micro-channel plates

NASA Astrophysics Data System (ADS)

Bornheim, A.; Apresyan, A.; Ronzhin, A.; Xie, S.; Spiropulu, M.; Trevor, J.; Pena, C.; Presutti, F.; Los, S.

2017-11-01

Future calorimeters and shower maximum detectors at high luminosity colliders need to be highly radiation resistant and very fast. One exciting option for such a detector is a calorimeter composed of a secondary emitter as the active element. In this report we outline the study and development of a secondary emission calorimeter prototype using micro-channel plates (MCP) as the active element, which directly amplify the electromagnetic shower signal. We demonstrate the feasibility of using a bare MCP within an inexpensive and robust housing without the need for any photo cathode, which is a key requirement for high radiation tolerance. Test beam measurements of the prototype were performed with 120 GeV primary protons and secondary beams at the Fermilab Test Beam Facility, demonstrating basic calorimetric measurements and precision timing capabilities. Using multiple pixel readout on the MCP, we demonstrate a transverse spatial resolution of 0.8 mm, and time resolution better than 40 ps for electromagnetic showers.

High-brightness laser imaging with tunable speckle reduction enabled by electroactive micro-optic diffusers.

PubMed

Farrokhi, Hamid; Rohith, Thazhe Madam; Boonruangkan, Jeeranan; Han, Seunghwoi; Kim, Hyunwoong; Kim, Seung-Woo; Kim, Young-Jin

2017-11-10

High coherence of lasers is desirable in high-speed, high-resolution, and wide-field imaging. However, it also causes unavoidable background speckle noise thus degrades the image quality in traditional microscopy and more significantly in interferometric quantitative phase imaging (QPI). QPI utilizes optical interference for high-precision measurement of the optical properties where the speckle can severely distort the information. To overcome this, we demonstrated a light source system having a wide tunability in the spatial coherence over 43% by controlling the illumination angle, scatterer's size, and the rotational speed of an electroactive-polymer rotational micro-optic diffuser. Spatially random phase modulation was implemented for the lower speckle imaging with over a 50% speckle reduction without a significant degradation in the temporal coherence. Our coherence control technique will provide a unique solution for a low-speckle, full-field, and coherent imaging in optically scattering media in the fields of healthcare sciences, material sciences and high-precision engineering.

Hybrid integration of III-V semiconductor lasers on silicon waveguides using optofluidic microbubble manipulation

PubMed Central

Jung, Youngho; Shim, Jaeho; Kwon, Kyungmook; You, Jong-Bum; Choi, Kyunghan; Yu, Kyoungsik

2016-01-01

Optofluidic manipulation mechanisms have been successfully applied to micro/nano-scale assembly and handling applications in biophysics, electronics, and photonics. Here, we extend the laser-based optofluidic microbubble manipulation technique to achieve hybrid integration of compound semiconductor microdisk lasers on the silicon photonic circuit platform. The microscale compound semiconductor block trapped on the microbubble surface can be precisely assembled on a desired position using photothermocapillary convective flows induced by focused laser beam illumination. Strong light absorption within the micro-scale compound semiconductor object allows real-time and on-demand microbubble generation. After the assembly process, we verify that electromagnetic radiation from the optically-pumped InGaAsP microdisk laser can be efficiently coupled to the single-mode silicon waveguide through vertical evanescent coupling. Our simple and accurate microbubble-based manipulation technique may provide a new pathway for realizing high precision fluidic assembly schemes for heterogeneously integrated photonic/electronic platforms as well as microelectromechanical systems. PMID:27431769

Precise pooling and dispensing of microfluidic droplets towards micro- to macro-world interfacing

PubMed Central

Brouzes, Eric; Carniol, April; Bakowski, Tomasz; Strey, Helmut H.

2014-01-01

Droplet microfluidics possesses unique properties such as the ability to carry out multiple independent reactions without dispersion of samples in microchannels. We seek to extend the use of droplet microfluidics to a new range of applications by enabling its integration into workflows based on traditional technologies, such as microtiter plates. Our strategy consists in developing a novel method to manipulate, pool and deliver a precise number of microfluidic droplets. To this aim, we present a basic module that combines droplet trapping with an on-chip valve. We quantitatively analyzed the trapping efficiency of the basic module in order to optimize its design. We also demonstrate the integration of the basic module into a multiplex device that can deliver 8 droplets at every cycle. This device will have a great impact in low throughput droplet applications that necessitate interfacing with macroscale technologies. The micro- to macro- interface is particularly critical in microfluidic applications that aim at sample preparation and has not been rigorously addressed in this context. PMID:25485102

Precision Timing with shower maximum detectors based on pixelated micro-channel plates

DOE PAGES

Bornheim, A.; Apresyan, A.; Ronzhin, A.; ...

2017-11-27

Future calorimeters and shower maximum detectors at high luminosity colliders need to be highly radiation resistant and very fast. One exciting option for such a detector is a calorimeter composed of a secondary emitter as the active element. Here, we outline the study and development of a secondary emission calorimeter prototype using micro-channel plates (MCP) as the active element, which directly amplify the electromagnetic shower signal. We also demonstrate the feasibility of using a bare MCP within an inexpensive and robust housing without the need for any photo cathode, which is a key requirement for high radiation tolerance. Test beammore » measurements of the prototype were performed with 120 GeV primary protons and secondary beams at the Fermilab Test Beam Facility, demonstrating basic calorimetric measurements and precision timing capabilities. Using multiple pixel readout on the MCP, we demonstrate a transverse spatial resolution of 0.8 mm, and time resolution better than 40 ps for electromagnetic showers.« less

The readout chain for the bar PANDA MVD strip detector

NASA Astrophysics Data System (ADS)

Schnell, R.; Brinkmann, K.-Th.; Di Pietro, V.; Kleines, H.; Goerres, A.; Riccardi, A.; Rivetti, A.; Rolo, M. D.; Sohlbach, H.; Zaunick, H.-G.

2015-02-01

The bar PANDA (antiProton ANnihilation at DArmstadt) experiment will study the strong interaction in annihilation reactions between an antiproton beam and a stationary gas jet target. The detector will comprise different sub-detectors for tracking, particle identification and calorimetry. The Micro-Vertex Detector (MVD) as the innermost part of the tracking system will allow precise tracking and detection of secondary vertices. For the readout of the double-sided silicon strip sensors a custom-made ASIC is being developed, employing the Time-over-Threshold (ToT) technique for digitization and utilize time-to-digital converters (TDC) to provide a high-precision time stamp of the hit. A custom-made Module Data Concentrator ASIC (MDC) will multiplex the data of all front-ends of one sensor towards the CERN-developed GBT chip set (GigaBit Transceiver). The MicroTCA-based MVD Multiplexer Board (MMB) at the off-detector site will receive and concentrate the data from the GBT links and transfer it to FPGA-based compute nodes for global event building.

Development of High Precision Metal Micro-Electro-Mechanical-Systems Column for Portable Surface Acoustic Wave Gas Chromatograph

NASA Astrophysics Data System (ADS)

Iwaya, Takamitsu; Akao, Shingo; Sakamoto, Toshihiro; Tsuji, Toshihiro; Nakaso, Noritaka; Yamanaka, Kazushi

2012-07-01

In the field of environmental measurement and security, a portable gas chromatograph (GC) is required for the on-site analysis of multiple hazardous gases. Although the gas separation column has been downsized using micro-electro-mechanical-systems (MEMS) technology, an MEMS column made of silicon and glass still does not have sufficient robustness and a sufficiently low fabrication cost for a portable GC. In this study, we fabricated a robust and inexpensive high-precision metal MEMS column by combining diffusion-bonded etched stainless-steel plates with alignment evaluation using acoustic microscopy. The separation performance was evaluated using a desktop GC with a flame ionization detector and we achieved the high separation performance comparable to the best silicon MEMS column fabricated using a dynamic coating method. As an application, we fabricated a palm-size surface acoustic wave (SAW) GC combining this column with a ball SAW sensor and succeeded in separating and detecting a mixture of volatile organic compounds.

Contribution of X/Ka VLBI to Multi-Wavelength Celestial Frame Studies

NASA Technical Reports Server (NTRS)

Jacobs, C. S.; Clark, J. E.; Garcia-Miro, C.; Horiuchi, S.; Sotuela, I.

2011-01-01

This paper is an update of Sotuela et al. (2011) which improves their simulated Gaia frame tie precision by approximately 10% by adding three additional VLBI observing sessions. Astrometry at X/Ka-band (8.4/32 GHz) using NASAs Deep Space Network has detected 466 quasars with accuracies of 200-300 micro-arc seconds. A program is underway to reduce errors by a factor of 2-3. From our sample, 245 sources have optical magnitudes V less than 20 and should also be detectable by Gaia. A covariance study using existing X/Ka data and simulated Gaia uncertainties for the 345 objects yields a frame tie precision of 10-15 micro-arc seconds (1 - sigma). The characterization of wavelength dependent systematic from extended source morphology and core shift should benefit greatly from adding X/Ka-band measurements to S/X-band (2.3/8.4 GHz) measurements thus helping to constrain astrophysical models of the wavelength dependence of positions.

Precision Timing with shower maximum detectors based on pixelated micro-channel plates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bornheim, A.; Apresyan, A.; Ronzhin, A.

Future calorimeters and shower maximum detectors at high luminosity colliders need to be highly radiation resistant and very fast. One exciting option for such a detector is a calorimeter composed of a secondary emitter as the active element. Here, we outline the study and development of a secondary emission calorimeter prototype using micro-channel plates (MCP) as the active element, which directly amplify the electromagnetic shower signal. We also demonstrate the feasibility of using a bare MCP within an inexpensive and robust housing without the need for any photo cathode, which is a key requirement for high radiation tolerance. Test beammore » measurements of the prototype were performed with 120 GeV primary protons and secondary beams at the Fermilab Test Beam Facility, demonstrating basic calorimetric measurements and precision timing capabilities. Using multiple pixel readout on the MCP, we demonstrate a transverse spatial resolution of 0.8 mm, and time resolution better than 40 ps for electromagnetic showers.« less

Emerging strategies for RNA interference (RNAi) applications in insects.

PubMed

Nandety, Raja Sekhar; Kuo, Yen-Wen; Nouri, Shahideh; Falk, Bryce W

2015-01-01

RNA interference (RNAi) in insects is a gene regulatory process that also plays a vital role in the maintenance and in the regulation of host defenses against invading viruses. Small RNAs determine the specificity of the RNAi through precise recognition of their targets. These small RNAs in insects comprise small interfering RNAs (siRNAs), micro RNAs (miRNAs) and Piwi interacting RNAs (piRNAs) of various lengths. In this review, we have explored different forms of the RNAi inducers that are presently in use, and their applications for an effective and efficient fundamental and practical RNAi research with insects. Further, we reviewed trends in next generation sequencing (NGS) technologies and their importance for insect RNAi, including the identification of novel insect targets as well as insect viruses. Here we also describe a rapidly emerging trend of using plant viruses to deliver the RNAi inducer molecules into insects for an efficient RNAi response.

A new fiber optic sensor for inner surface roughness measurement

NASA Astrophysics Data System (ADS)

Xu, Xiaomei; Liu, Shoubin; Hu, Hong

2009-11-01

In order to measure inner surface roughness of small holes nondestructively, a new fiber optic sensor is researched and developed. Firstly, a new model for surface roughness measurement is proposed, which is based on intensity-modulated fiber optic sensors and scattering modeling of rough surfaces. Secondly, a fiber optical measurement system is designed and set up. Under the help of new techniques, the fiber optic sensor can be miniaturized. Furthermore, the use of micro prism makes the light turn 90 degree, so the inner side surface roughness of small holes can be measured. Thirdly, the fiber optic sensor is gauged by standard surface roughness specimens, and a series of measurement experiments have been done. The measurement results are compared with those obtained by TR220 Surface Roughness Instrument and Form Talysurf Laser 635, and validity of the developed fiber optic sensor is verified. Finally, precision and influence factors of the fiber optic sensor are analyzed.

Hot gas path component having near wall cooling features

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miranda, Carlos Miguel; Kottilingam, Srikanth Chandrudu; Lacy, Benjamin Paul

A method for providing micro-channels in a hot gas path component includes forming a first micro-channel in an exterior surface of a substrate of the hot gas path component. A second micro-channel is formed in the exterior surface of the hot gas path component such that it is separated from the first micro-channel by a surface gap having a first width. The method also includes disposing a braze sheet onto the exterior surface of the hot gas path component such that the braze sheet covers at least of portion of the first and second micro-channels, and heating the braze sheetmore » to bond it to at least a portion of the exterior surface of the hot gas path component.« less

Dynamic alignment, tolerances, and metrology fundamentals at the nano and micro scales

NASA Astrophysics Data System (ADS)

Silberman, Donn M.

2015-09-01

Although the terms "micropositioning" and "nanopositioning" refer to different classes of positioning systems, "nanopositioning" is often used mistakenly to describe micropositioning systems. Micropositioning systems are typically motor-driven stages with travel ranges of a few millimeters up to a few hundred millimeters. Because the guiding systems in such stages — usually bearings of some kind — generate frictional forces, their resolution and repeatability are typically limited to 0.1 μm. The guiding system working principle also adds errors that are typically in the micrometer range. Nanopositioning systems are typically based on frictionless drives and guiding systems such as piezo actuators and flexures. These systems can achieve resolutions and guiding accuracies down to the sub-nanometer level. Both of these classes of precision positioning and motion systems are used extensively in precision optical and photonic systems to achieve desired performance specifications of instruments and experimental research projects. Currently, many precision positioning and motion systems have been design and implemented to cross over from the micro to the nano ranges with excellent results. This paper will describe some of the fundamental performance parameters and tolerances typical of these systems, some of the metrology used to confirm specifications and a few high end applications of general interest.

Comparison of three different techniques for application of water solutions to Finn Chambers®.

PubMed

Frick-Engfeldt, Malin; Gruvberger, Birgitta; Isaksson, Marléne; Hauksson, Inese; Pontén, Ann; Bruze, Magnus

2010-11-01

With regard to contact allergy, the dose of a sensitizer per unit skin area is an important factor for both sensitization and elicitation, and therefore a known amount/volume of test preparation should be applied at patch testing. To compare three different techniques for the application of aqueous solutions to Finn Chambers, in order to determine the precision and accuracy of each technique when the recommended 15 µl volume is applied. Four technicians applied formaldehyde 1.0% aq. (wt/vol) and methylchloroisothiazolinone/methylisothiazolinone 200 ppm (wt/vol) in sets of 10 onto Finn Chambers, with three different techniques: (i) micro-pipetting; (ii) dripping the solutions; and (iii) dripping the solutions followed by removal of excess solution with a soft tissue. Assessment of the variations was performed with the use of descriptive data. The ability to apply the exact amount was assessed by Fisher's exact test by categorizing each application as in or out of the range 12-18 µl. The micro-pipette technique had the best accuracy and precision, as well as the lowest inter-individual variation. The technique in which excess solution was removed had good precision, but failed in the application of the defined amount, i.e. 15 µl. © 2010 John Wiley & Sons A/S.

Ductile cutting of silicon microstructures with surface inclination measurement and compensation by using a force sensor integrated single point diamond tool

NASA Astrophysics Data System (ADS)

Chen, Yuan-Liu; Cai, Yindi; Shimizu, Yuki; Ito, So; Gao, Wei; Ju, Bing-Feng

2016-02-01

This paper presents a measurement and compensation method of surface inclination for ductile cutting of silicon microstructures by using a diamond tool with a force sensor based on a four-axis ultra-precision lathe. The X- and Y-directional inclinations of a single crystal silicon workpiece with respect to the X- and Y-motion axes of the lathe slides were measured respectively by employing the diamond tool as a touch-trigger probe, in which the tool-workpiece contact is sensitively detected by monitoring the force sensor output. Based on the measurement results, fabrication of silicon microstructures can be thus carried out directly along the tilted silicon workpiece by compensating the cutting motion axis to be parallel to the silicon surface without time-consuming pre-adjustment of the surface inclination or turning of a flat surface. A diamond tool with a negative rake angle was used in the experiment for superior ductile cutting performance. The measurement precision by using the diamond tool as a touch-trigger probe was investigated. Experiments of surface inclination measurement and ultra-precision ductile cutting of a micro-pillar array and a micro-pyramid array with inclination compensation were carried out respectively to demonstrate the feasibility of the proposed method.

Design of a self-adaptive fuzzy PID controller for piezoelectric ceramics micro-displacement system

NASA Astrophysics Data System (ADS)

Zhang, Shuang; Zhong, Yuning; Xu, Zhongbao

2008-12-01

In order to improve control precision of the piezoelectric ceramics (PZT) micro-displacement system, a self-adaptive fuzzy Proportional Integration Differential (PID) controller is designed based on the traditional digital PID controller combining with fuzzy control. The arithmetic gives a fuzzy control rule table with the fuzzy control rule and fuzzy reasoning, through this table, the PID parameters can be adjusted online in real time control. Furthermore, the automatic selective control is achieved according to the change of the error. The controller combines the good dynamic capability of the fuzzy control and the high stable precision of the PID control, adopts the method of using fuzzy control and PID control in different segments of time. In the initial and middle stage of the transition process of system, that is, when the error is larger than the value, fuzzy control is used to adjust control variable. It makes full use of the fast response of the fuzzy control. And when the error is smaller than the value, the system is about to be in the steady state, PID control is adopted to eliminate static error. The problems of PZT existing in the field of precise positioning are overcome. The results of the experiments prove that the project is correct and practicable.

Precise Temperature Mapping of GaN-Based LEDs by Quantitative Infrared Micro-Thermography

PubMed Central

Chang, Ki Soo; Yang, Sun Choel; Kim, Jae-Young; Kook, Myung Ho; Ryu, Seon Young; Choi, Hae Young; Kim, Geon Hee

2012-01-01

A method of measuring the precise temperature distribution of GaN-based light-emitting diodes (LEDs) by quantitative infrared micro-thermography is reported. To reduce the calibration error, the same measuring conditions were used for both calibration and thermal imaging; calibration was conducted on a highly emissive black-painted area on a dummy sapphire wafer loaded near the LED wafer on a thermoelectric cooler mount. We used infrared thermal radiation images of the black-painted area on the dummy wafer and an unbiased LED wafer at two different temperatures to determine the factors that degrade the accuracy of temperature measurement, i.e., the non-uniform response of the instrument, superimposed offset radiation, reflected radiation, and emissivity map of the LED surface. By correcting these factors from the measured infrared thermal radiation images of biased LEDs, we determined a precise absolute temperature image. Consequently, we could observe from where the local self-heat emerges and how it distributes on the emitting area of the LEDs. The experimental results demonstrated that highly localized self-heating and a remarkable temperature gradient, which are detrimental to LED performance and reliability, arise near the p-contact edge of the LED surface at high injection levels owing to the current crowding effect. PMID:22666050

New laser machining processes for shape memory alloys

NASA Astrophysics Data System (ADS)

Haferkamp, Heinz; Paschko, Stefan; Goede, Martin

2001-04-01

Due to special material properties, shape memory alloys (SMA) are finding increasing attention in micro system technology. However, only a few processes are available for the machining of miniaturized SMA-components. In this connection, laser material processing offers completely new possibilities. This paper describes the actual status of two projects that are being carried out to qualify new methods to machine SMA components by means of laser radiation. Within one project, the laser material ablation process of miniaturized SMA- components using ultra-short laser pulses (pulse duration: approx. 200 fs) in comparison to conventional laser material ablation is being investigated. Especially for SMA micro- sensors and actuators, it is important to minimize the heat affected zone (HAZ) to maintain the special mechanical properties. Light-microscopic investigations of the grain texture of SMA devices processed with ultra-short laser pulses show that the HAZ can be neglected. Presently, the main goal of the project is to qualify this new processing technique for the micro-structuring of complex SMA micro devices with high precision. Within a second project, investigations are being carried out to realize the induction of the two-way memory effect (TWME) into SMA components using laser radiation. By precisely heating SMA components with laser radiation, local tensions remain near the component surface. In connection with the shape memory effect, these tensions can be used to make the components execute complicated movements. Compared to conventional training methods to induce the TWME, this procedure is faster and easier. Furthermore, higher numbers of thermal cycling are expected because of the low dislocation density in the main part of the component.

Linear electrostatic micromotors for nano- and micro-positioning

NASA Astrophysics Data System (ADS)

Baginsky, I. L.; Kostsov, Edvard G.

2004-05-01

The functioning of the linear step electrostatic film micromotors with the short controlling pulse (less then 100-200 ´s) is studied to create nano- and micro-positioners. The theoretical study of the step movement of the given mass in this time frame is carried out. The results of the experimental studies of the multipetal reciprocal micromotors created on the basis of La modified Ba0.5Sr0.5Nb2O6 ferroelectric films with 1-3 μm thickness are shown. The petals were made of beryllium bronze. It is shown that the electrostatic rolling can last less than 50 μs, and the process of separating two surfaces (the metal and the ferroelectric) can last less than 1 μs. These parameters allow one to operate the micromotor at 1-10 kHz frequency, and the propulsion force in the beginning (the first 20-100 μs) of the electrostatic rolling can be as high as 1-10 N per 1 mm2 of the rolling surface with the voltage pulse amplitude of 40-50 V. The possibility of obtaining moving plate (MP) step in the nanometer range is studied, as well as the precision of these steps during the continuous MP movement with the different clock frequencies and durations of the voltage pulses. The recommendations are given to improve the accuracy and the speed of the positioning in the nano- and micro-movement range. Possible fields of micromotor application are micromechanics, including precision micromechanics, microelectronics, microrobots, microoptics, microscanners, micropumps (e.g. in the jet printers), micro flying vehicles etc.

COMPARISON OF MINIMUM INHIBITORY CONCENTRATION OF WATER SOLUBLE EXTRACTS OF EUGENIA JAMBOLANA LAM. (FAM. MYRTACEAE) BARKS OF DIFFERENT AGES ON DYSENTERY AND DIARRHOEA FORMING MICRO – ORGANISMS

PubMed Central

Maiti, Asis Prosun; Pal, Subodh Chandra; Chattopadhyay, Debaprasad; De, Samar; Nandy, Anutosh

1985-01-01

A preliminary investigations was carried out to study the antibacterial activity of the water soluble extracts of five and ten years old barks of Eugenia Jambolana Lam. (fam. Myrtaceae) on dysentery and diarrhoea forming micro organisms. It was observed that the barks of young plants have a better inhibitory effect on micro – organisms like Salmonella viballerup, Shigella dysenteriae 10, Shigella boydii 5, Sgigella dysenteriae 2. PMID:22557509

Laser 3D micro-manufacturing

NASA Astrophysics Data System (ADS)

Piqué, Alberto; Auyeung, Raymond C. Y.; Kim, Heungsoo; Charipar, Nicholas A.; Mathews, Scott A.

2016-06-01

Laser-based materials processing techniques are gaining widespread use in micro-manufacturing applications. The use of laser microfabrication techniques enables the processing of micro- and nanostructures from a wide range of materials and geometries without the need for masking and etching steps commonly associated with photolithography. This review aims to describe the broad applications space covered by laser-based micro- and nanoprocessing techniques and the benefits offered by the use of lasers in micro-manufacturing processes. Given their non-lithographic nature, these processes are also referred to as laser direct-write and constitute some of the earliest demonstrations of 3D printing or additive manufacturing at the microscale. As this review will show, the use of lasers enables precise control of the various types of processing steps—from subtractive to additive—over a wide range of scales with an extensive materials palette. Overall, laser-based direct-write techniques offer multiple modes of operation including the removal (via ablative processes) and addition (via photopolymerization or printing) of most classes of materials using the same equipment in many cases. The versatility provided by these multi-function, multi-material and multi-scale laser micro-manufacturing processes cannot be matched by photolithography nor with other direct-write microfabrication techniques and offer unique opportunities for current and future 3D micro-manufacturing applications.

Study on a two-dimensional scanning micro-mirror and its application in a MOEMS target detector.

PubMed

Zhang, Chi; You, Zheng; Huang, Hu; Li, Guanhua

2010-01-01

A two-dimensional (2D) scanning micro-mirror for target detection and measurement has been developed. This new micro-mirror is used in a MOEMS target detector to replace the conventional scanning detector. The micro-mirror is fabricated by MEMS process and actuated by a piezoelectric actuator. To achieve large deflection angles, the micro-mirror is excited in the resonance modes. It has two degrees of freedom and changes the direction of the emitted laser beam for a regional 2D scanning. For the deflection angles measurement, piezoresistors are integrated in the micro-mirror and the deflection angles of each direction can be detected independently and precisely. Based on the scanning micro-mirror and the phase-shift ranging technology, a MOEMS target detector has been developed in a size of 90 mm × 35 mm × 50 mm. The experiment shows that the target can be detected in the scanning field and the relative range and orientation can be measured by the MOEMS target detector. For the target distance up to 3 m with a field of view about 20° × 20°, the measurement resolution is about 10.2 cm in range, 0.15° in the horizontal direction and 0.22° in the vertical direction for orientation.

Study on a Two-Dimensional Scanning Micro-Mirror and Its Application in a MOEMS Target Detector

PubMed Central

Zhang, Chi; You, Zheng; Huang, Hu; Li, Guanhua

2010-01-01

A two-dimensional (2D) scanning micro-mirror for target detection and measurement has been developed. This new micro-mirror is used in a MOEMS target detector to replace the conventional scanning detector. The micro-mirror is fabricated by MEMS process and actuated by a piezoelectric actuator. To achieve large deflection angles, the micro-mirror is excited in the resonance modes. It has two degrees of freedom and changes the direction of the emitted laser beam for a regional 2D scanning. For the deflection angles measurement, piezoresistors are integrated in the micro-mirror and the deflection angles of each direction can be detected independently and precisely. Based on the scanning micro-mirror and the phase-shift ranging technology, a MOEMS target detector has been developed in a size of 90 mm × 35 mm × 50 mm. The experiment shows that the target can be detected in the scanning field and the relative range and orientation can be measured by the MOEMS target detector. For the target distance up to 3 m with a field of view about 20° × 20°, the measurement resolution is about 10.2 cm in range, 0.15° in the horizontal direction and 0.22° in the vertical direction for orientation. PMID:22163580

Autonomous, agile micro-satellites and supporting technologies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Breitfeller, E; Dittman, M D; Gaughan, R J

1999-07-19

This paper updates the on-going effort at Lawrence Livermore National Laboratory to develop autonomous, agile micro-satellites (MicroSats). The objective of this development effort is to develop MicroSats weighing only a few tens of kilograms, that are able to autonomously perform precision maneuvers and can be used telerobotically in a variety of mission modes. The required capabilities include satellite rendezvous, inspection, proximity-operations, docking, and servicing. The MicroSat carries an integrated proximity-operations sensor-suite incorporating advanced avionics. A new self-pressurizing propulsion system utilizing a miniaturized pump and non-toxic mono-propellant hydrogen peroxide was successfully tested. This system can provide a nominal 25 kg MicroSatmore » with 200-300 m/s delta-v including a warm-gas attitude control system. The avionics is based on the latest PowerPC processor using a CompactPCI bus architecture, which is modular, high-performance and processor-independent. This leverages commercial-off-the-shelf (COTS) technologies and minimizes the effects of future changes in processors. The MicroSat software development environment uses the Vx-Works real-time operating system (RTOS) that provides a rapid development environment for integration of new software modules, allowing early integration and test. We will summarize results of recent integrated ground flight testing of our latest non-toxic pumped propulsion MicroSat testbed vehicle operated on our unique dynamic air-rail.« less

Photovoltaic system with improved DC connections and method of making same

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cioffi, Philip Michael; Todorovic, Maja Harfman; Herzog, Michael Scott

A micro-inverter assembly includes a housing having an opening formed in a bottom surface thereof, and a direct current (DC)-to-alternating current (AC) micro-inverter disposed within the housing at a position adjacent to the opening. The micro-inverter assembly further includes a micro-inverter DC connector electrically coupled to the DC-to-AC micro-inverter and positioned within the opening of the housing, the micro-inverter DC connector having a plurality of exposed electrical contacts.

Study on Platinum Coating Depth in Focused Ion Beam Diamond Cutting Tool Milling and Methods for Removing Platinum Layer.

PubMed

Choi, Woong Kirl; Baek, Seung Yub

2015-09-22

In recent years, nanomachining has attracted increasing attention in advanced manufacturing science and technologies as a value-added processes to control material structures, components, devices, and nanoscale systems. To make sub-micro patterns on these products, micro/nanoscale single-crystal diamond cutting tools are essential. Popular non-contact methods for the macro/micro processing of diamond composites are pulsed laser ablation (PLA) and electric discharge machining (EDM). However, for manufacturing nanoscale diamond tools, these machining methods are not appropriate. Despite diamond's extreme physical properties, diamond can be micro/nano machined relatively easily using a focused ion beam (FIB) technique. In the FIB milling process, the surface properties of the diamond cutting tool is affected by the amorphous damage layer caused by the FIB gallium ion collision and implantation and these influence the diamond cutting tool edge sharpness and increase the processing procedures. To protect the diamond substrate, a protection layer-platinum (Pt) coating is essential in diamond FIB milling. In this study, the depth of Pt coating layer which could decrease process-induced damage during FIB fabrication is investigated, along with methods for removing the Pt coating layer on diamond tools. The optimum Pt coating depth has been confirmed, which is very important for maintaining cutting tool edge sharpness and decreasing processing procedures. The ultra-precision grinding method and etching with aqua regia method have been investigated for removing the Pt coating layer. Experimental results show that when the diamond cutting tool width is bigger than 500 nm, ultra-precision grinding method is appropriate for removing Pt coating layer on diamond tool. However, the ultra-precision grinding method is not recommended for removing the Pt coating layer when the cutting tool width is smaller than 500 nm, because the possibility that the diamond cutting tool is damaged by the grinding process will be increased. Despite the etching method requiring more procedures to remove the Pt coating layer after FIB milling, it is a feasible method for diamond tools with under 500 nm width.

Efficient digitalization method for dental restorations using micro-CT data

NASA Astrophysics Data System (ADS)

Kim, Changhwan; Baek, Seung Hoon; Lee, Taewon; Go, Jonggun; Kim, Sun Young; Cho, Seungryong

2017-03-01

The objective of this study was to demonstrate the feasibility of using micro-CT scan of dental impressions for fabricating dental restorations and to compare the dimensional accuracy of dental models generated from various methods. The key idea of the proposed protocol is that dental impression of patients can be accurately digitized by micro-CT scan and that one can make digital cast model from micro-CT data directly. As air regions of the micro-CT scan data of dental impression are equivalent to the real teeth and surrounding structures, one can segment the air regions and fabricate digital cast model in the STL format out of them. The proposed method was validated by a phantom study using a typodont with prepared teeth. Actual measurement and deviation map analysis were performed after acquiring digital cast models for each restoration methods. Comparisons of the milled restorations were also performed by placing them on the prepared teeth of typodont. The results demonstrated that an efficient fabrication of precise dental restoration is achievable by use of the proposed method.

Electro-thermal modelling of anode and cathode in micro-EDM

NASA Astrophysics Data System (ADS)

Yeo, S. H.; Kurnia, W.; Tan, P. C.

2007-04-01

Micro-electrical discharge machining is an evolution of conventional EDM used for fabricating three-dimensional complex micro-components and microstructure with high precision capabilities. However, due to the stochastic nature of the process, it has not been fully understood. This paper proposes an analytical model based on electro-thermal theory to estimate the geometrical dimensions of micro-crater. The model incorporates voltage, current and pulse-on-time during material removal to predict the temperature distribution on the workpiece as a result of single discharges in micro-EDM. It is assumed that the entire superheated area is ejected from the workpiece surface while only a small fraction of the molten area is expelled. For verification purposes, single discharge experiments using RC pulse generator are performed with pure tungsten as the electrode and AISI 4140 alloy steel as the workpiece. For the pulse-on-time range up to 1000 ns, the experimental and theoretical results are found to be in close agreement with average volume approximation errors of 2.7% and 6.6% for the anode and cathode, respectively.

In situ thermomechanical testing methods for micro/nano-scale materials.

PubMed

Kang, Wonmo; Merrill, Marriner; Wheeler, Jeffrey M

2017-02-23

The advance of micro/nanotechnology in energy-harvesting, micropower, electronic devices, and transducers for automobile and aerospace applications has led to the need for accurate thermomechanical characterization of micro/nano-scale materials to ensure their reliability and performance. This persistent need has driven various efforts to develop innovative experimental techniques that overcome the critical challenges associated with precise mechanical and thermal control of micro/nano-scale specimens during material characterization. Here we review recent progress in the development of thermomechanical testing methods from miniaturized versions of conventional macroscopic test systems to the current state of the art of in situ uniaxial testing capabilities in electron microscopes utilizing either indentation-based microcompression or integrated microsystems. We discuss the major advantages/disadvantages of these methods with respect to specimen size, range of temperature control, ease of experimentation and resolution of the measurements. We also identify key challenges in each method. Finally, we summarize some of the important discoveries that have been made using in situ thermomechanical testing and the exciting research opportunities still to come in micro/nano-scale materials.

A micro-coupling for micro mechanical systems

NASA Astrophysics Data System (ADS)

Li, Wei; Zhou, Zhixiong; Zhang, Bi; Xiao, Yunya

2016-05-01

The error motions of micro mechanical systems, such as micro-spindles, increase with the increasing of the rotational speed, which not only decreases the rotational accuracy, but also promotes instability and limits the maximum operational speed. One effective way to deal with it is to use micro-flexible couplings between the drive and driven shafts so as to reduce error motions of the driven shaft. But the conventional couplings, such as diaphragm couplings, elastomeric couplings, bellows couplings, and grooved couplings, etc, cannot be directly used because of their large and complicated structures. This study presents a novel micro-coupling that consists of a flexible coupling and a shape memory alloy (SMA)-based clamp for micro mechanical systems. It is monolithic and can be directly machined from a shaft. The study performs design optimization and provides manufacturing considerations, including thermo-mechanical training of the SMA ring for the desired Two-Way-Shape-Memory effect (TWSMe). A prototype micro-coupling and a prototype micro-spindle using the proposed coupling are fabricated and tested. The testing results show that the prototype micro-coupling can bear a torque of above 5 N • mm and an axial force of 8.5 N and be fitted with an SMA ring for clamping action at room temperature (15 °C) and unclamping action below-5 °C. At the same time, the prototype micro-coupling can work at a rotational speed of above 200 kr/min with the application to a high-speed precision micro-spindle. Moreover, the radial runout error of the artifact, as a substitute for the micro-tool, is less than 3 μm while that of turbine shaft is above 7 μm. It can be concluded that the micro-coupling successfully accommodates misalignment errors of the prototype micro-spindle. This research proposes a micro-coupling which is featured with an SMA ring, and it is designed to clamp two shafts, and has smooth transmission, simple assembly, compact structure, zero-maintenance and balanced motions.

Identification of micro-RNA expression profile related to recurrence in women with ESMO low-risk endometrial cancer.

PubMed

de Foucher, Tiphaine; Sbeih, Maria; Uzan, Jenifer; Bendifallah, Sofiane; Lefevre, Marine; Chabbert-Buffet, Nathalie; Aractingi, Selim; Uzan, Catherine; Abd Alsalam, Issam; Mitri, Rana; Fontaine, Romain H; Daraï, Emile; Haddad, Bassam; Méhats, Céline; Ballester, Marcos; Canlorbe, Geoffroy; Touboul, Cyril

2018-05-21

Actual European pathological classification of early-stage endometrial cancer (EC) may show insufficient accuracy to precisely stratify recurrence risk, leading to potential over or under treatment. Micro-RNAs are post-transcriptional regulators involved in carcinogenic mechanisms, with some micro-RNA patterns of expression associated with EC characteristics and prognosis. We previously demonstrated that downregulation of micro-RNA-184 was associated with lymph node involvement in low-risk EC (LREC). The aim of this study was to evaluate whether micro-RNA signature in tumor tissues from LREC women can be correlated with the occurrence of recurrences. MicroRNA expression was assessed by chip analysis and qRT-PCR in 7 formalin-fixed paraffin-embedded (FFPE) LREC primary tumors from women whose follow up showed recurrences (R+) and in 14 FFPE LREC primary tumors from women whose follow up did not show any recurrence (R-), matched for grade and age. Various statistical analyses, including enrichment analysis and a minimum p-value approach, were performed. The expression levels of micro-RNAs-184, -497-5p, and -196b-3p were significantly lower in R+ compared to R- women. Women with a micro-RNA-184 fold change < 0.083 were more likely to show recurrence (n = 6; 66%) compared to those with a micro-RNA-184 fold change > 0.083 (n = 1; 8%), p = 0.016. Women with a micro-RNA-196 fold change < 0.56 were more likely to show recurrence (n = 5; 100%) compared to those with a micro-RNA-196 fold change > 0.56 (n = 2; 13%), p = 0.001. These findings confirm the great interest of micro-RNA-184 as a prognostic tool to improve the management of LREC women.

Adenosine formation and release from neonatal-rat heart cells in culture.

PubMed Central

Meghji, P; Holmquist, C A; Newby, A C

1985-01-01

The incorporation of [3H]adenosine (10 microM) into neonatal-rat heart cell nucleotides was inhibited in a concentration-dependent manner, such that 50% inhibition was obtained with 0.75 microM-dipyridamole, 0.26 microM-hexobendine or 0.22 microM-dilazep. Adenosine formation was accelerated 2.5-fold to 2.1 +/- 0.3 nmol/10(7) cells in 10 min when cells were incubated with a combination of 30 mM-2-deoxyglucose and 2 micrograms of oligomycin/ml. Of the newly formed adenosine, 6 +/- 2% was in the cells. Dipyridamole, hexobendine or dilazep (10 microM) increased the amount of adenosine in the cells and decreased that in the medium such that 45-50% of the newly formed adenosine was in the cells. Antibodies which inhibited ecto-5'-nucleotidase by 98.7 +/- 0.3% did not alter the rate of adenosine formation or its distribution between cells and medium. We conclude that adenosine was formed in the cytoplasm during catabolism of cellular ATP and was released via the dipyridamole-sensitive symmetric nucleoside transporter. PMID:2996488

Method for producing micro heat panels

NASA Technical Reports Server (NTRS)

Camarda, Charles J. (Inventor); Peterson, George P. (Inventor); Rummler, Donald R. (Inventor)

1997-01-01

Flat or curved micro heat pipe panels are fabricated by arranging essentially parallel filaments in the shape of the desired panel. The configuration of the filaments corresponds to the desired configuration of the tubes that will constitute the heat pipes. A thermally conductive material is then deposited on and around the filaments to fill in the desired shape of the panel. The filaments are then removed, leaving tubular passageways of the desired configuration and surface texture in the material. The tubes are then filled with a working fluid and sealed. Composite micro heat pipe laminates are formed by layering individual micro heat pipe panels and bonding them to each other to form a single structure. The layering sequence of the micro heat pipe panels can be tailored to transport heat preferentially in specific directions as desired for a particular application.

Narrow-angle Astrometry with SUSI

NASA Astrophysics Data System (ADS)

Kok, Y.; Ireland, M. J.; Robertson, J. G.; Tuthill, P. G.; Warrington, B. A.; Tango, W. J.

2014-09-01

SUSI (Sydney University Stellar Interferometer) is currently being fitted with a 2nd beam combiner, MUSCA (Micro-arcsecond University of Sydney Companion Astrometry), for the purpose of narrow-angle astrometry. With an aim to achieve ˜10 micro-arcseconds of angular resolution at its best, MUSCA allows SUSI to search for planets around bright binary stars, which are its primary targets. While the first beam combiner, PAVO (Precision Astronomical Visible Observations), is used to track stellar fringes during an observation, MUSCA will be used to measure separations of binary stars. MUSCA is a Michelson interferometer and its setup at SUSI will be described in this poster.

Laser micro-etching of metal prostheses for personal identification

PubMed Central

Ganapathy, Dhanraj; Sivaswamy, Vinay; Sekhar, Prathap

2017-01-01

Denture marking techniques play a vital role in establishing personal identification in suitable clinical and forensic situations. The denture marking techniques are categorized broadly into additive and ablative methods. Additive methods involve embedding or impregnation of markers for establishing personal identity. Ablative methods involve partial removal of the denture surface thereby providing a marking for identification. Engraving and etching methods are the commonly used ablative methods. Ablative methods can be of contact and noncontact subtypes. Laser micro-etching is a precise noncontact ablative denture marking technique that could be used for prostheses-guided personal identification. PMID:28584473

Laser micro-etching of metal prostheses for personal identification.

PubMed

Ganapathy, Dhanraj; Sivaswamy, Vinay; Sekhar, Prathap

2017-01-01

Denture marking techniques play a vital role in establishing personal identification in suitable clinical and forensic situations. The denture marking techniques are categorized broadly into additive and ablative methods. Additive methods involve embedding or impregnation of markers for establishing personal identity. Ablative methods involve partial removal of the denture surface thereby providing a marking for identification. Engraving and etching methods are the commonly used ablative methods. Ablative methods can be of contact and noncontact subtypes. Laser micro-etching is a precise noncontact ablative denture marking technique that could be used for prostheses-guided personal identification.

Using a Gatling-Gun Configured Micro Pulsed Plasma Thruster as a Means to Control Micro Satellites with Extreme Precision

DTIC Science & Technology

2011-03-01

machine gun , or distributor cap in an automobile. In a Gatling- Gun , when the barrel rotates it collects a round and as the round rotates, it comes...ejected and another is fed into the barrel . This design allows multiple rounds to be fired from the gun very quickly, and still prevent the barrel from...T6061 aluminum and had dimensions of (127 x 76.2 x76.2) mm, cross sectional area of 5.80644 *10-3 m2 and a volume of 7.374*10-4 m3. Using the volume

Breakthrough in current-in-plane tunneling measurement precision by application of multi-variable fitting algorithm.

PubMed

Cagliani, Alberto; Østerberg, Frederik W; Hansen, Ole; Shiv, Lior; Nielsen, Peter F; Petersen, Dirch H

2017-09-01

We present a breakthrough in micro-four-point probe (M4PP) metrology to substantially improve precision of transmission line (transfer length) type measurements by application of advanced electrode position correction. In particular, we demonstrate this methodology for the M4PP current-in-plane tunneling (CIPT) technique. The CIPT method has been a crucial tool in the development of magnetic tunnel junction (MTJ) stacks suitable for magnetic random-access memories for more than a decade. On two MTJ stacks, the measurement precision of resistance-area product and tunneling magnetoresistance was improved by up to a factor of 3.5 and the measurement reproducibility by up to a factor of 17, thanks to our improved position correction technique.

Advances in molecular dynamics simulation of ultra-precision machining of hard and brittle materials

NASA Astrophysics Data System (ADS)

Guo, Xiaoguang; Li, Qiang; Liu, Tao; Kang, Renke; Jin, Zhuji; Guo, Dongming

2017-03-01

Hard and brittle materials, such as silicon, SiC, and optical glasses, are widely used in aerospace, military, integrated circuit, and other fields because of their excellent physical and chemical properties. However, these materials display poor machinability because of their hard and brittle properties. Damages such as surface micro-crack and subsurface damage often occur during machining of hard and brittle materials. Ultra-precision machining is widely used in processing hard and brittle materials to obtain nanoscale machining quality. However, the theoretical mechanism underlying this method remains unclear. This paper provides a review of present research on the molecular dynamics simulation of ultra-precision machining of hard and brittle materials. The future trends in this field are also discussed.

Soil physics: a Moroccan perspective

NASA Astrophysics Data System (ADS)

Lahlou, Sabah; Mrabet, Rachid; Ouadia, Mohamed

2004-06-01

Research on environmental pollution and degradation of soil and water resources is now of highest priority worldwide. To address these problems, soil physics should be conceived as a central core to this research. This paper objectives are to: (1) address the role and importance of soil physics, (2) demonstrate progress in this discipline, and (3) present various uses of soil physics in research, environment and industry. The study of dynamic processes at and within the soil vadose zone (flow, dispersion, transport, sedimentation, etc.), and ephemeral phenomena (deformation, compaction, etc.), form an area of particular interest in soil physics. Soil physics has changed considerably over time. These changes are due to needed precision in data collection for accurate interpretation of space and time variation of soil properties. Soil physics interacts with other disciplines and sciences such as hydro(geo)logy, agronomy, environment, micro-meteorology, pedology, mathematics, physics, water sciences, etc. These interactions prompted the emergence of advanced theories and comprehensive mechanisms of most natural processes, development of new mathematical tools (modeling and computer simulation, fractals, geostatistics, transformations), creation of high precision instrumentation (computer assisted, less time constraint, increased number of measured parameters) and the scale sharpening of physical measurements which ranges from micro to watershed. The environment industry has contributed to an enlargement of many facets of soil physics. In other words, research demand in soil physics has increased considerably to satisfy specific and environmental problems (contamination of water resources, global warming, etc.). Soil physics research is still at an embryonic stage in Morocco. Consequently, soil physicists can take advantage of developments occurring overseas, and need to build up a database of soil static and dynamic properties and to revise developed models to meet our conditions. Large, but special, investment is required to promote research programs in soil physics, which consider developments in this discipline and respect Moroccan needs. These programs will be highlighted herein.

Micro-engineering a platform to reconstruct physiology and functionality of the human brain microvasculature in vitro

NASA Astrophysics Data System (ADS)

Daghighi, Yasaman; Heidari, Hossein; Taylor, Hayden

2018-02-01

A predominant unsolved challenge in tissue engineering is the need of a robust technique for producing vascular networks, particularly when modeling human brain tissue. The availability of reliable in vitro human brain microvasculature models would advance our understanding of its function and would provide a platform for highthroughput drug screening. Current strategies for modeling vascularized brain tissue suffer from limitations such as (1) culturing non-human cell lines, (2) limited multi-cell co-culture, and (3) the effects of neighboring physiologically unrealistic rigid polymeric surfaces, such as solid membranes. We demonstrate a new micro-engineered platform that can address these shortcomings. Specifically, we have designed and prototyped a molding system to enable the precise casting of 100μm-diameter coaxial hydrogel structures laden with the requisite cells to mimic a vascular lumen. Here we demonstrate that a fine wire with diameter 130 μm or a needle with outer diameter 300 μm can be used as a temporary mold insert, and agarose-collagen composite matrix can be cast around these inserts and thermally gelled. When the wire or needle is retracted under the precise positional control afforded by our system, a microchannel is formed which is then seeded with human microvascular endothelial cells. After seven days of culture these cells produce an apparently confluent monolayer on the channel walls. In principle, this platform could be used to create multilayered cellular structures. By arranging a fine wire and a hollow needle coaxially, three distinct zones could be defined in the model: first, the bulk gel surrounding the needle; then, after needle retraction, a cylindrical shell of matrix; and finally, after retraction of the wire, a lumen. Each zone could be independently cell-seeded. To this end, we have also successfully 3D cultured human astrocytes and SY5Y glial cells in our agarose-collagen matrix. Our approach ultimately promises scalable and repeatable production of vascular structures with physiologically realistic mechanical properties.

Modeling of flow stress size effect based on variation of dislocation substructure in micro-tension of pure nickel

NASA Astrophysics Data System (ADS)

Wang, Chuanjie; Liu, Huan; Zhang, Ying; Chen, Gang; Li, Yujie; Zhang, Peng

2017-12-01

Micro-forming is one promising technology for manufacturing micro metal parts. However, the traditional metal-forming theories fail to analyze the plastic deformation behavior in micro-scale due to the size effect arising from the part geometry scaling down from macro-scale to micro-scale. To reveal the mechanism of plastic deformation behavior size effect in micro-scale, the geometrical parameters and the induced variation of microstructure by them need to be integrated in the developed constitutive models considering the free surface effect. In this research, the variations of dislocation cell diameter with original grain size, strain and location (surface grain or inner grain) are derived according the previous research data. Then the overall flow stress of the micro specimen is determined by employing the surface layer model and the relationship between dislocation cell diameter and the flow stress. This new developed constitutive model considers the original grain size, geometrical dimension and strain simultaneously. The flow stresses in micro-tensile tests of thin sheets are compared with calculated results using the developed constitutive model. The calculated and experimental results match well. Thus the validity of the developed constitutive model is verified.

Bubble Departure from Metal-Graphite Composite Surfaces and Its Effects on Pool Boiling Heat Transfer

NASA Technical Reports Server (NTRS)

Chao, David F.; Sankovic, John M.; Motil, Brian J.; Yang, W-J.; Zhang, Nengli

2010-01-01

The formation and growth processes of a bubble in the vicinity of graphite micro-fiber tips on metal-graphite composite boiling surfaces and their effects on boiling behavior are investigated. It is discovered that a large number of micro bubbles are formed first at the micro scratches and cavities on the metal matrix in pool boiling. By virtue of the non-wetting property of graphite, once the growing micro bubbles touch the graphite tips, the micro bubbles are sucked by the tips and merged into larger micro bubbles sitting on the end of the tips. The micro bubbles grow rapidly and coalesce to form macro bubbles, each spanning several tips. The necking process of a detaching macro bubble is analyzed. It is revealed that a liquid jet is produced by sudden break-off of the bubble throat. The composite surfaces not only have higher temperatures in micro- and macrolayers but also make higher frequency of the bubble departure, which increase the average heat fluxes in both the bubble growth stage and in the bubble departure period. Based on these analyses, the enhancement mechanism of pool boiling heat transfer on composite surfaces is clearly revealed.

Research on the Problem of High-Precision Deployment for Large-Aperture Space-Based Science Instruments

NASA Technical Reports Server (NTRS)

Lake, Mark S.; Peterson, Lee D.; Hachkowski, M. Roman; Hinkle, Jason D.; Hardaway, Lisa R.

1998-01-01

The present paper summarizes results from an ongoing research program conducted jointly by the University of Colorado and NASA Langley Research Center since 1994. This program has resulted in general guidelines for the design of high-precision deployment mechanisms, and tests of prototype deployable structures incorporating these mechanisms have shown microdynamically stable behavior (i.e., dimensional stability to parts per million). These advancements have resulted from the identification of numerous heretofore unknown microdynamic and micromechanical response phenomena, and the development of new test techniques and instrumentation systems to interrogate these phenomena. In addition, recent tests have begun to interrogate nanomechanical response of materials and joints and have been used to develop an understanding of nonlinear nanodynamic behavior in microdynamically stable structures. The ultimate goal of these efforts is to enable nano-precision active control of micro-precision deployable structures (i.e., active control to a resolution of parts per billion).

Single-cell-precision microplasma-induced cancer cell apoptosis.

PubMed

Tan, Xiao; Zhao, Shasha; Lei, Qian; Lu, Xinpei; He, Guangyuan; Ostrikov, Kostya

2014-01-01

The issue of single-cell control has recently attracted enormous interest. However, in spite of the presently achievable intracellular-level physiological probing through bio-photonics, nano-probe-based, and some other techniques, the issue of inducing selective, single-cell-precision apoptosis, without affecting neighbouring cells remains essentially open. Here we resolve this issue and report on the effective single-cell-precision cancer cell treatment using the reactive chemistry of the localized corona-type plasma discharge around a needle-like electrode with the spot size ∼1 µm. When the electrode is positioned with the micrometer precision against a selected cell, a focused and highly-localized micro-plasma discharge induces apoptosis in the selected individual HepG2 and HeLa cancer cells only, without affecting any surrounding cells, even in small cell clusters. This is confirmed by the real-time monitoring of the morphological and structural changes at the cellular and cell nucleus levels after the plasma exposure.

Automatic computational labeling of glomerular textural boundaries

NASA Astrophysics Data System (ADS)

Ginley, Brandon; Tomaszewski, John E.; Sarder, Pinaki

2017-03-01

The glomerulus, a specialized bundle of capillaries, is the blood filtering unit of the kidney. Each human kidney contains about 1 million glomeruli. Structural damages in the glomerular micro-compartments give rise to several renal conditions; most severe of which is proteinuria, where excessive blood proteins flow freely to the urine. The sole way to confirm glomerular structural damage in renal pathology is by examining histopathological or immunofluorescence stained needle biopsies under a light microscope. However, this method is extremely tedious and time consuming, and requires manual scoring on the number and volume of structures. Computational quantification of equivalent features promises to greatly ease this manual burden. The largest obstacle to computational quantification of renal tissue is the ability to recognize complex glomerular textural boundaries automatically. Here we present a computational pipeline to accurately identify glomerular boundaries with high precision and accuracy. The computational pipeline employs an integrated approach composed of Gabor filtering, Gaussian blurring, statistical F-testing, and distance transform, and performs significantly better than standard Gabor based textural segmentation method. Our integrated approach provides mean accuracy/precision of 0.89/0.97 on n = 200Hematoxylin and Eosin (HE) glomerulus images, and mean 0.88/0.94 accuracy/precision on n = 200 Periodic Acid Schiff (PAS) glomerulus images. Respective accuracy/precision of the Gabor filter bank based method is 0.83/0.84 for HE and 0.78/0.8 for PAS. Our method will simplify computational partitioning of glomerular micro-compartments hidden within dense textural boundaries. Automatic quantification of glomeruli will streamline structural analysis in clinic, and can help realize real time diagnoses and interventions.

Fabrication of PDMS through-holes using the MIMIC method and the surface treatment by atmospheric-pressure CH4/He RF plasma

NASA Astrophysics Data System (ADS)

Choi, Jongchan; Lee, Kyeong-Hwan; Yang, Sung

2011-09-01

This note presents a simple fabrication process for patterning micro through-holes in a PDMS layer by a combination of the micromolding in capillaries (MIMIC) method and the surface treatment by atmospheric-pressure CH4/He RF plasma. The fabrication process is confirmed by forming micro through-holes with various shapes including circle, C-shape, open microfluidic channel and hemisphere. All micro through-holes of various shapes in a wide range of diameters and heights are well fabricated by the proposed method. Also, a 3D micromixer containing a PDMS micro through-hole layer formed by the proposed method is built and its performance is tested as another practical demonstration of the proposed fabrication method. Therefore, we believe that the proposed fabrication process will build a PDMS micro through-hole layer in a simple and easy way and will contribute to developing highly efficient multi-layered microfluidic systems, which may require PDMS micro through-hole layers.

Plasmofluidics: Merging Light and Fluids at the Micro-/Nano-Scale

PubMed Central

Wang, Mingsong; Zhao, Chenglong; Miao, Xiaoyu; Zhao, Yanhui; Rufo, Joseph

2016-01-01

Plasmofluidics is the synergistic integration of plasmonics and micro/nano fluidics in devices and applications in order to enhance performance. There has been significant progress in the emerging field of plasmofluidics in recent years. By utilizing the capability of plasmonics to manipulate light at the nanoscale, combined with the unique optical properties of fluids, and precise manipulation via micro/nano fluidics, plasmofluidic technologies enable innovations in lab-on-a-chip systems, reconfigurable photonic devices, optical sensing, imaging, and spectroscopy. In this review article, we examine and categorize the most recent advances in plasmofluidics into plasmon-enhanced functionalities in microfluidics and microfluidics-enhanced plasmonic devices. The former focuses on plasmonic manipulations of fluids, bubbles, particles, biological cells, and molecules at the micro-/nano-scale. The latter includes technological advances that apply microfluidic principles to enable reconfigurable plasmonic devices and performance-enhanced plasmonic sensors. We conclude with our perspectives on the upcoming challenges, opportunities, and the possible future directions of the emerging field of plasmofluidics. PMID:26140612

Relationship of Interplanetary Shock Micro and Macro Characteristics: A Wind Study

NASA Technical Reports Server (NTRS)

Szabo, Adam; Koval, A

2008-01-01

The non-linear least squared MHD fitting technique of Szabo 11 9941 has been recently further refined to provide realistic confidence regions for interplanetary shock normal directions and speeds. Analyzing Wind observed interplanetary shocks from 1995 to 200 1, macro characteristics such as shock strength, Theta Bn and Mach numbers can be compared to the details of shock micro or kinetic structures. The now commonly available very high time resolution (1 1 or 22 vectors/sec) Wind magnetic field data allows the precise characterization of shock kinetic structures, such as the size of the foot, ramp, overshoot and the duration of damped oscillations on either side of the shock. Detailed comparison of the shock micro and macro characteristics will be given. This enables the elucidation of shock kinetic features, relevant for particle energization processes, for observations where high time resolution data is not available. Moreover, establishing a quantitative relationship between the shock micro and macro structures will improve the confidence level of shock fitting techniques during disturbed solar wind conditions.

Plasmofluidics: Merging Light and Fluids at the Micro-/Nanoscale.

PubMed

Wang, Mingsong; Zhao, Chenglong; Miao, Xiaoyu; Zhao, Yanhui; Rufo, Joseph; Liu, Yan Jun; Huang, Tony Jun; Zheng, Yuebing

2015-09-16

Plasmofluidics is the synergistic integration of plasmonics and micro/nanofluidics in devices and applications in order to enhance performance. There has been significant progress in the emerging field of plasmofluidics in recent years. By utilizing the capability of plasmonics to manipulate light at the nanoscale, combined with the unique optical properties of fluids and precise manipulation via micro/nanofluidics, plasmofluidic technologies enable innovations in lab-on-a-chip systems, reconfigurable photonic devices, optical sensing, imaging, and spectroscopy. In this review article, the most recent advances in plasmofluidics are examined and categorized into plasmon-enhanced functionalities in microfluidics and microfluidics-enhanced plasmonic devices. The former focuses on plasmonic manipulations of fluids, bubbles, particles, biological cells, and molecules at the micro/nanoscale. The latter includes technological advances that apply microfluidic principles to enable reconfigurable plasmonic devices and performance-enhanced plasmonic sensors. The article is concluded with perspectives on the upcoming challenges, opportunities, and possible future directions of the emerging field of plasmofluidics. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Applications of X-Ray Micro-Beam for Data Collection.

PubMed

Sanishvili, Ruslan; Fischetti, Robert F

2017-01-01

Micro-diffraction tools for macromolecular crystallography, first developed at the end of 1990s and now an integral part of many synchrotron beamlines, enable some of the experiments which were not feasible just a decade or so ago. These include data collection from very small samples, just a few micrometers in size; from larger, but severely inhomogeneous samples; and from samples which are optically invisible. Improved micro-diffraction tools led to improved signal-to-noise ratio, to mitigation of radiation damage in some cases, and to better-designed diffraction experiments. Small, micron-scale beams can be attained in different ways and knowing the details of the implementation is important in order to design the diffraction experiment properly. Similarly, precision, reproducibility and stability of the goniometry, and caveats of detection systems need to be taken into account. Lastly, to make micro-diffraction widely applicable, the sophistication, robustness, and user-friendliness of these tools are just as important as the technical capabilities.

Imaging techniques for visualizing and phenotyping congenital heart defects in murine models.

PubMed

Liu, Xiaoqin; Tobita, Kimimasa; Francis, Richard J B; Lo, Cecilia W

2013-06-01

Mouse model is ideal for investigating the genetic and developmental etiology of congenital heart disease. However, cardiovascular phenotyping for the precise diagnosis of structural heart defects in mice remain challenging. With rapid advances in imaging techniques, there are now high throughput phenotyping tools available for the diagnosis of structural heart defects. In this review, we discuss the efficacy of four different imaging modalities for congenital heart disease diagnosis in fetal/neonatal mice, including noninvasive fetal echocardiography, micro-computed tomography (micro-CT), micro-magnetic resonance imaging (micro-MRI), and episcopic fluorescence image capture (EFIC) histopathology. The experience we have gained in the use of these imaging modalities in a large-scale mouse mutagenesis screen have validated their efficacy for congenital heart defect diagnosis in the tiny hearts of fetal and newborn mice. These cutting edge phenotyping tools will be invaluable for furthering our understanding of the developmental etiology of congenital heart disease. Copyright © 2013 Wiley Periodicals, Inc.

Tailored optical vector fields for ultrashort-pulse laser induced complex surface plasmon structuring.

PubMed

Ouyang, J; Perrie, W; Allegre, O J; Heil, T; Jin, Y; Fearon, E; Eckford, D; Edwardson, S P; Dearden, G

2015-05-18

Precise tailoring of optical vector beams is demonstrated, shaping their focal electric fields and used to create complex laser micro-patterning on a metal surface. A Spatial Light Modulator (SLM) and a micro-structured S-waveplate were integrated with a picosecond laser system and employed to structure the vector fields into radial and azimuthal polarizations with and without a vortex phase wavefront as well as superposition states. Imprinting Laser Induced Periodic Surface Structures (LIPSS) elucidates the detailed vector fields around the focal region. In addition to clear azimuthal and radial plasmon surface structures, unique, variable logarithmic spiral micro-structures with a pitch Λ ∼1μm, not observed previously, were imprinted on the surface, confirming unambiguously the complex 2D focal electric fields. We show clearly also how the Orbital Angular Momentum(OAM) associated with a helical wavefront induces rotation of vector fields along the optic axis of a focusing lens and confirmed by the observed surface micro-structures.

Isolation and Characterization of a microRNA-size Secretable Small RNA in Streptococcus sanguinis.

PubMed

Choi, Ji-Woong; Kwon, Tae-Yub; Hong, Su-Hyung; Lee, Heon-Jin

2018-06-01

MicroRNAs in eukaryotic cells are thought to control highly complex signal transduction and other biological processes by regulating coding transcripts, accounting for their important role in cellular events in eukaryotes. Recently, a novel class of bacterial RNAs similar in size [18-22 nucleotides (nt)] to microRNAs has been reported. Herein, we describe microRNAs, small RNAs from the oral pathogen Streptococcus sanguinis. The bacteria are normally present in the oral cavities and cause endocarditis by contaminating bloodstreams. Small RNAs were analyzed by deep sequencing. Selected highly expressed small RNAs were further validated by real-time polymerase chain reaction and northern blot analyses. We found that skim milk supplement changed the expression of small RNAs S.S-1964 in tandem with the nearby SSA_0513 gene involved in vitamin B 12 conversion. We furthermore observed small RNAs secreted via bacterial membrane vesicles. Although their precise function remains unclear, secretable small RNAs may represent an entirely new area of study in bacterial genetics.

Ultra-precise micro-motion stage for optical scanning test

NASA Astrophysics Data System (ADS)

Chen, Wen; Zhang, Jianhuan; Jiang, Nan

2009-05-01

This study aims at the application of optical sensing technology in a 2D flexible hinge test stage. Optical fiber sensor which is manufactured taking advantage of the various unique properties of optical fiber, such as good electric insulation properties, resistance of electromagnetic disturbance, sparkless property and availability in flammable and explosive environment, has lots of good properties, such as high accuracy and wide dynamic range, repeatable, etc. and is applied in 2D flexible hinge stage driven by PZT. Several micro-bending structures are designed utilizing the characteristics of the flexible hinge stage. And through experiments, the optimal micro-bending tooth structure and the scope of displacement sensor trip under this optimal micro-bending tooth structure are derived. These experiments demonstrate that the application of optical fiber displacement sensor in 2D flexible hinge stage driven by PZT substantially broadens the dynamic testing range and improves the sensitivity of this apparatus. Driving accuracy and positioning stability are enhanced as well. [1,2

Improving the Cell Viability and Isolating Precision of Laser-induced Forward Transfer Process by Maintaining a Proper Environment with a Microchip.

PubMed

Deng, Yu; Huang, Zhigang; Wang, Wenbing; Chen, Yinghuai; Guo, Zhongning; Chen, Ying

2017-01-01

Aiming to improve the laser-induced forward transfer (LIFT) cell isolation process, a polydimethylsiloxane (PDMS) layer with micro-hole arrays was employed to improve the cell separation precision, and a microchip with heater was developed to maintain the working area at 100% humidity and 37°C with the purpose to preserve the viability of the isolated cells. A series of experiments were conducted to verify the contributions of the optimization to LIFT cell isolation process as well as to study the effect of laser pulse energy, laser spot size and the titanium thickness on cell isolation. With 40µm laser spot size and 40nm thick of titanium, laser energy threshold for 100% single cell isolating succeed ratio is 7µJ. According to the staining images and proliferation ratios, the chip did help to improve the cell availability and the cells can recover from the juries at least a day earlier comparing to the samples processed without the chip. With a Lattice Boltzmann model, the cell isolation process is numerically studied and it turns out that the micro-hole makes the isolation process shift to a micro-syringe injection model leading to the lower laser energy threshold for cell separation and fewer injuries. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Silicon Micro- and Nanofabrication for Medicine

PubMed Central

Fine, Daniel; Goodall, Randy; Bansal, Shyam S.; Chiappini, Ciro; Hosali, Sharath; van de Ven, Anne L.; Srinivasan, Srimeenkashi; Liu, Xuewu; Godin, Biana; Brousseau, Louis; Yazdi, Iman K.; Fernandez-Moure, Joseph; Tasciotti, Ennio; Wu, Hung-Jen; Hu, Ye; Klemm, Steve; Ferrari, Mauro

2013-01-01

This manuscript constitutes a review of several innovative biomedical technologies fabricated using the precision and accuracy of silicon micro- and nanofabrication. The technologies to be reviewed are subcutaneous nanochannel drug delivery implants for the continuous tunable zero-order release of therapeutics, multi-stage logic embedded vectors for the targeted systemic distribution of both therapeutic and imaging contrast agents, silicon and porous silicon nanowires for investigating cellular interactions and processes as well as for molecular and drug delivery applications, porous silicon (pSi) as inclusions into biocomposites for tissue engineering, especially as it applies to bone repair and regrowth, and porous silica chips for proteomic profiling. In the case of the biocomposites, the specifically designed pSi inclusions not only add to the structural robustness, but can also promote tissue and bone regrowth, fight infection, and reduce pain by releasing stimulating factors and other therapeutic agents stored within their porous network. The common material thread throughout all of these constructs, silicon and its associated dielectrics (silicon dioxide, silicon nitride, etc.), can be precisely and accurately machined using the same scalable micro- and nanofabrication protocols that are ubiquitous within the semiconductor industry. These techniques lend themselves to the high throughput production of exquisitely defined and monodispersed nanoscale features that should eliminate architectural randomness as a source of experimental variation thereby potentially leading to more rapid clinical translation. PMID:23584841

Silicon/SU8 multi-electrode micro-needle for in vivo neurochemical monitoring.

PubMed

Vasylieva, Natalia; Marinesco, Stéphane; Barbier, Daniel; Sabac, Andrei

2015-10-15

Simultaneous monitoring of glucose and lactate is an important challenge for understanding brain energetics in physiological or pathological states. We demonstrate here a versatile method based on a minimally invasive single implantation in the rat brain. A silicon/SU8-polymer multi-sensing needle-shaped biosensor, was fabricated and tested. The multi-electrode array design comprises three platinum planar microelectrodes with a surface area of 40 × 200 µm(2) and a spacing of 200 µm, which were micromachined on a single 3mm long micro-needle having a 100 × 50 µm(2) cross-section for reduced tissue damage during implantation. Platinum micro-electrodes were aligned at the bottom of micro-wells obtained by photolithography on a SU8 photoresist layer. After clean room processing, each micro-electrode was functionalized inside the micro-wells by means of a micro-dispensing device, either with glucose oxidase or with lactate oxidase, which were cross-linked on the platinum electrodes. The third electrode covered with Bovine Serum Albumin (BSA) was used for the control of non-specific currents. The thick SU8 photoresist layer has revealed excellent electrical insulation of the micro-electrodes and between interconnection lines, and ensured a precise localization and packaging of the sensing enzymes on platinum micro-electrodes. During in vitro calibration with concentrations of analytes in the mM range, the micro-wells patterned in the SU8 photoresist proved to be highly effective in eliminating cross-talk signals, caused by H2O2 diffusion from closely spaced micro-electrodes. Moreover, our biosensor was successfully assayed in the rat cortex for simultaneous monitoring of both glucose and lactate during insulin and glucose administration. Copyright © 2015 Elsevier B.V. All rights reserved.

Modeling and evaluating of surface roughness prediction in micro-grinding on soda-lime glass considering tool characterization

NASA Astrophysics Data System (ADS)

Cheng, Jun; Gong, Yadong; Wang, Jinsheng

2013-11-01

The current research of micro-grinding mainly focuses on the optimal processing technology for different materials. However, the material removal mechanism in micro-grinding is the base of achieving high quality processing surface. Therefore, a novel method for predicting surface roughness in micro-grinding of hard brittle materials considering micro-grinding tool grains protrusion topography is proposed in this paper. The differences of material removal mechanism between convention grinding process and micro-grinding process are analyzed. Topography characterization has been done on micro-grinding tools which are fabricated by electroplating. Models of grain density generation and grain interval are built, and new predicting model of micro-grinding surface roughness is developed. In order to verify the precision and application effect of the surface roughness prediction model proposed, a micro-grinding orthogonally experiment on soda-lime glass is designed and conducted. A series of micro-machining surfaces which are 78 nm to 0.98 μm roughness of brittle material is achieved. It is found that experimental roughness results and the predicting roughness data have an evident coincidence, and the component variable of describing the size effects in predicting model is calculated to be 1.5×107 by reverse method based on the experimental results. The proposed model builds a set of distribution to consider grains distribution densities in different protrusion heights. Finally, the characterization of micro-grinding tools which are used in the experiment has been done based on the distribution set. It is concluded that there is a significant coincidence between surface prediction data from the proposed model and measurements from experiment results. Therefore, the effectiveness of the model is demonstrated. This paper proposes a novel method for predicting surface roughness in micro-grinding of hard brittle materials considering micro-grinding tool grains protrusion topography, which would provide significant research theory and experimental reference of material removal mechanism in micro-grinding of soda-lime glass.

Effect of Micro-Bubbles in Water on Beam Patterns of Parametric Array

NASA Astrophysics Data System (ADS)

Hashiba, Kunio; Masuzawa, Hiroshi

2003-05-01

The improvement in efficiency of a parametric array by nonlinear oscillation of micro-bubbles in water is studied in this paper. The micro-bubble oscillation can increase the nonlinear coefficient of the acoustic medium. The amplitude of the difference-frequency wave along the longitudinal axis and its beam patterns in the field including the layer with micro-bubbles were analyzed using a Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation. As a result, the largest improvement in efficiency was obtained and a narrow parametric beam was formed by forming a layer with micro-bubbles in front of a parametric sound radiator as thick as about the shock formation distance. If the layer becomes significantly thicker than the distance, the beam of the difference-frequency wave in the far-field will become broader. If the layer is significantly thinner than the distance, the intensity level of the wave in the far-field will be too low.

Fabrication of micro/nano-structures by electrohydrodynamic jet technique

NASA Astrophysics Data System (ADS)

Wang, Dazhi; Zhao, Xiaojun; Lin, Yigao; Ren, Tongqun; Liang, Junsheng; Liu, Chong; Wang, Liding

2017-12-01

Electrohydrodynamic jet (E-Jet) is an approach to the fabrication of micro/nano-structures by the use of electrical forces. In this process, the liquid is subjected to electrical and mechanical forces to form a liquid jet, which is further disintegrated into droplets. The major advantage of the E-Jet technique is that the sizes of the jet formed can be at the nanoscale far smaller than the nozzle size, which can realize high printing resolution with less risk of nozzle blockage. The E-Jet technique, which mainly includes E-Jet deposition and E-Jet printing, has a wide range of applications in the fabrication of micro/nano-structures for micro/nano-electromechanical system devices. This technique is also considered a micro/nano-fabrication method with a great potential for commercial use. This study mainly reviews the E-Jet deposition/printing fundamentals, fabrication process, and applications.

Impact of viscosity variation and micro rotation on oblique transport of Cu-water fluid.

PubMed

Tabassum, Rabil; Mehmood, R; Nadeem, S

2017-09-01

This study inspects the influence of temperature dependent viscosity on Oblique flow of micropolar nanofluid. Fluid viscosity is considered as an exponential function of temperature. Governing equations are converted into dimensionless forms with aid of suitable transformations. Outcomes of the study are shown in graphical form and discussed in detail. Results revealed that viscosity parameter has pronounced effects on velocity profiles, temperature distribution, micro-rotation, streamlines, shear stress and heat flux. It is found that viscosity parameter enhances the temperature distribution, tangential velocity profile, normal component of micro-rotation and shear stress at the wall while it has decreasing effect on tangential component of micro-rotation and local heat flux. Copyright © 2017 Elsevier Inc. All rights reserved.

Micro-instillation of fluorescein with an inoculation loop for ocular surface staining in dry eye syndrome.

PubMed

Courrier, Emilie; Renault, Didier; Kaspi, Mathilde; Marcon, Agathe; Lambert, Victor; Garcin, Thibaud; Chiambaretta, Frederic; Garhofer, Gerhard; Thuret, Gilles; Gain, Philippe

2018-03-01

To describe and validate the micro-instillation of fluorescein on the ocular surface by a disposable calibrated inoculation loop to improve corneal and conjunctival staining quality. Accuracy and precision of the volume of 0.5% sodium fluorescein collected by a single use 1 μl-calibrated inoculation loop were measured using a precision balance. Twenty patients (40 eyes) suffering from dry eye syndrome were enrolled in a prospective interventional nonrandomized study. Fluorescein was instilled with the loop, and slit-lamp images were taken within 30 seconds using cobalt blue light with and without a yellow barrier filter. For comparison, after a washout period, the same images were retaken after instillation of one drop of fluorescein from a single-dose unit. The main outcome measure was the staining quality assessed by three experts, blind to the instillation method. Patient discomfort (tolerance, by a questionnaire) was also compared. The mean volume collected by the loop was 1.18 ± 0.12 μl, compared with 33.70 ± 6.10 μl using the single-dose unit. The loop avoided excess dye responsible for unpleasant tearing, masking of lesions and rapid diffusion into the stroma. Micro-instillation greatly improved image quality without losing information. The yellow filter further improved image contrast. Tolerance was excellent. The 1 μl-calibrated inoculation loop is a safe, convenient, inexpensive, disposable, sterile, well-tolerated tool for reproducible micro-instillation of commercial fluorescein. By greatly improving staining quality, it will help standardize assessment of dry eye severity. © 2017 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Combustor nozzles in gas turbine engines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Thomas Edward; Keener, Christopher Paul; Stewart, Jason Thurman

2017-09-12

A micro-mixer nozzle for use in a combustor of a combustion turbine engine, the micro-mixer nozzle including: a fuel plenum defined by a shroud wall connecting a periphery of a forward tube sheet to a periphery of an aft tubesheet; a plurality of mixing tubes extending across the fuel plenum for mixing a supply of compressed air and fuel, each of the mixing tubes forming a passageway between an inlet formed through the forward tubesheet and an outlet formed through the aft tubesheet; and a wall mixing tube formed in the shroud wall.

Narrow energy band gap gallium arsenide nitride semi-conductors and an ion-cut-synthesis method for producing the same

DOEpatents

Weng, Xiaojun; Goldman, Rachel S.

2006-06-06

A method for forming a semi-conductor material is provided that comprises forming a donor substrate constructed of GaAs, providing a receiver substrate, implanting nitrogen into the donor substrate to form an implanted layer comprising GaAs and nitrogen. The implanted layer is bonded to the receiver substrate and annealed to form GaAsN and nitrogen micro-blisters in the implanted layer. The micro-blisters allow the implanted layer to be cleaved from the donor substrate.

Simulation of Aluminum Micro-mirrors for Space Applications at Cryogenic Temperatures

NASA Technical Reports Server (NTRS)

Kuhn, J. L.; Dutta, S. B.; Greenhouse, M. A.; Mott, D. B.

2000-01-01

Closed form and finite element models are developed to predict the device response of aluminum electrostatic torsion micro-mirrors fabricated on silicon substrate for space applications at operating temperatures of 30K. Initially, closed form expressions for electrostatic pressure arid mechanical restoring torque are used to predict the pull-in and release voltages at room temperature. Subsequently, a detailed mechanical finite element model is developed to predict stresses and vertical beam deflection induced by the electrostatic and thermal loads. An incremental and iterative solution method is used in conjunction with the nonlinear finite element model and closed form electrostatic equations to solve. the coupled electro-thermo-mechanical problem. The simulation results are compared with experimental measurements at room temperature of fabricated micro-mirror devices.

Optimal design and experimental analyses of a new micro-vibration control payload-platform

NASA Astrophysics Data System (ADS)

Sun, Xiaoqing; Yang, Bintang; Zhao, Long; Sun, Xiaofen

2016-07-01

This paper presents a new payload-platform, for precision devices, which possesses the capability of isolating the complex space micro-vibration in low frequency range below 5 Hz. The novel payload-platform equipped with smart material actuators is investigated and designed through optimization strategy based on the minimum energy loss rate, for the aim of achieving high drive efficiency and reducing the effect of the magnetic circuit nonlinearity. Then, the dynamic model of the driving element is established by using the Lagrange method and the performance of the designed payload-platform is further discussed through the combination of the controlled auto regressive moving average (CARMA) model with modified generalized prediction control (MGPC) algorithm. Finally, an experimental prototype is developed and tested. The experimental results demonstrate that the payload-platform has an impressive potential of micro-vibration isolation.

[Detection of marginal leakage of Class V restorations in vitro by micro-CT].

PubMed

Gu, Lin-juan; Zhao, Xin-yi; Li, Shi-bao

2012-09-01

To evaluate the reliability and superiority of micro-CT in marginal leakage assessment of Class V restorations. Class V preparations with gingival margins in dentin and occlusal in enamel were made in sixteen extracted non-carious human molars and restored with dental bonding agents and composite resin. All teeth were then immersed in 50% ammonia-silver nitrate solution for 12 hours, followed by developing solution for 8 hours. Each restoration was scanned by a micro-CT and silver leakage was measured and three-dimensional image of the silver leakage alone cavity wall were reconstructed. Afterward, all restorations were sectioned and examined for leakage depth using a microscope. The silver leakage depth of each restoration obtained by micro-CT and microscope were compared for equivalency. The silver leakage depths in gingival wall obtained with micro-CT (0.78 mm) and microscope (0.74 mm) showed no significant difference (P > 0.05), while the judgment of leakage depths in occlusal wall in micro-CT image (0.40 mm) was affected by adjacent enamel structure, giving less leakage depths compared to microscope (0.72 mm)(P < 0.01). The three-dimensional shapes of the microleakages displayed clearly by micro-CT alone wall of Class V restorations were multiform and some leakages showed channels on their way to spreading. Micro-CT can detect precisely the silver leakage in the dentin wall of a restoration and display its three-dimensional shape fully. Enamel structure affects the detection of the silver leakage next to it.

3D mapping of polymerization shrinkage using X-ray micro-computed tomography to predict microleakage.

PubMed

Sun, Jirun; Eidelman, Naomi; Lin-Gibson, Sheng

2009-03-01

The objectives of this study were to (1) demonstrate X-ray micro-computed tomography (microCT) as a viable method for determining the polymerization shrinkage and microleakage on the same sample accurately and non-destructively, and (2) investigate the effect of sample geometry (e.g., C-factor and volume) on polymerization shrinkage and microleakage. Composites placed in a series of model cavities of controlled C-factors and volumes were imaged using microCT to determine their precise location and volume before and after photopolymerization. Shrinkage was calculated by comparing the volume of composites before and after polymerization and leakage was predicted based on gap formation between composites and cavity walls as a function of position. Dye penetration experiments were used to validate microCT results. The degree of conversion (DC) of composites measured using FTIR microspectroscopy in reflectance mode was nearly identical for composites filled in all model cavity geometries. The shrinkage of composites calculated based on microCT results was statistically identical regardless of sample geometry. Microleakage, on the other hand, was highly dependent on the C-factor as well as the composite volume, with higher C-factors and larger volumes leading to a greater probability of microleakage. Spatial distribution of microleakage determined by microCT agreed well with results determined by dye penetration. microCT has proven to be a powerful technique in quantifying polymerization shrinkage and corresponding microleakage for clinically relevant cavity geometries.

DIANA-microT web server: elucidating microRNA functions through target prediction.

PubMed

Maragkakis, M; Reczko, M; Simossis, V A; Alexiou, P; Papadopoulos, G L; Dalamagas, T; Giannopoulos, G; Goumas, G; Koukis, E; Kourtis, K; Vergoulis, T; Koziris, N; Sellis, T; Tsanakas, P; Hatzigeorgiou, A G

2009-07-01

Computational microRNA (miRNA) target prediction is one of the key means for deciphering the role of miRNAs in development and disease. Here, we present the DIANA-microT web server as the user interface to the DIANA-microT 3.0 miRNA target prediction algorithm. The web server provides extensive information for predicted miRNA:target gene interactions with a user-friendly interface, providing extensive connectivity to online biological resources. Target gene and miRNA functions may be elucidated through automated bibliographic searches and functional information is accessible through Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. The web server offers links to nomenclature, sequence and protein databases, and users are facilitated by being able to search for targeted genes using different nomenclatures or functional features, such as the genes possible involvement in biological pathways. The target prediction algorithm supports parameters calculated individually for each miRNA:target gene interaction and provides a signal-to-noise ratio and a precision score that helps in the evaluation of the significance of the predicted results. Using a set of miRNA targets recently identified through the pSILAC method, the performance of several computational target prediction programs was assessed. DIANA-microT 3.0 achieved there with 66% the highest ratio of correctly predicted targets over all predicted targets. The DIANA-microT web server is freely available at www.microrna.gr/microT.

Synchrotron radiation μCT and histology evaluation of bone-to-implant contact.

PubMed

Neldam, Camilla Albeck; Sporring, Jon; Rack, Alexander; Lauridsen, Torsten; Hauge, Ellen-Margrethe; Jørgensen, Henrik L; Jørgensen, Niklas Rye; Feidenhansl, Robert; Pinholt, Else Marie

2017-09-01

The purpose of this study was to evaluate bone-to-implant contact (BIC) in two-dimensional (2D) histology compared to high-resolution three-dimensional (3D) synchrotron radiation micro computed tomography (SR micro-CT). High spatial resolution, excellent signal-to-noise ratio, and contrast establish SR micro-CT as the leading imaging modality for hard X-ray microtomography. Using SR micro-CT at voxel size 5 μm in an experimental goat mandible model, no statistically significant difference was found between the different treatment modalities nor between recipient and reconstructed bone. The histological evaluation showed a statistically significant difference between BIC in reconstructed and recipient bone (p < 0.0001). Further, no statistically significant difference was found between the different treatment modalities which we found was due to large variation and subsequently due to low power. Comparing histology and SR micro-CT evaluation a bias of 5.2% was found in reconstructed area, and 15.3% in recipient bone. We conclude that for evaluation of BIC with histology and SR micro-CT, SR micro-CT cannot be proven more precise than histology for evaluation of BIC, however, with this SR micro-CT method, one histologic bone section is comparable to the 3D evaluation. Further, the two methods complement each other with knowledge on BIC in 2D and 3D. Copyright © 2017 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

[Comparative study of root canal morphology of mandibular first premolar by micro-CT and radio visio graphy].

PubMed

Li, Xiangjie; Liu, Na; Liu, Rui; Dong, Zhengmou; Liu, Luchuan; Deng, Manjing

2012-02-01

To compare the consistency of root canal configuration types of mandibular first premolar by using micro-CT and radio visio graphy (RVG). One hundred extracted mandibular first premolars with complete dental root and apex which received no endodontic treatment were randomly selected. Each tooth was radiographed with RVG through a buccolingual and mesiodistal direction, and then scanned with micro-CT and reconstructed. The classifications of the root canal types according to Vertucci's type with the two methods were compared. The canal patterns were classified as type I (67%), type III (3%), type V (18%), type VII (2%), additional type (10%) with micro-CT and canal patterns as type I (71%), type III (2%), type V (23%), type VII (1%), additional type (3%) with RVG. 63% of teeth showed one canal in both micro-CT and RVG. Only 25% of teeth were diagnosed as complex canal by the same canal type in both micro-CT and RVG. The Kappa value between micro-CT and RVG was 0.541 which suggested that the two kinds of methods had intermediate consistency. 82.8% of the premolars with root groove had two or more than two canals. Although RVG can basically reflect the root canal system type of the mandibular first premolars in vitro, it offers poor accuracy images to complex root canals. Micro-CT three-dimensional images could clearly and precisely display the root canal system morphology of the mandibular first pre-molars in vitro.

Micro-electromembrane extraction across free liquid membranes. Instrumentation and basic principles.

PubMed

Kubáň, Pavel; Boček, Petr

2014-06-13

A micro-electromembrane extraction (μ-EME) technique using electrically induced transfer of charged analytes across free liquid membranes (FLMs) was presented. A disposable extraction unit was proposed and it was made of a short segment of transparent perfluoroalkoxy tubing, which was successively filled with three liquid plugs serving as acceptor solution, FLM and donor solution. These plugs formed a three-phase extraction system, which was precisely defined, that was stable and required μL to sub-μL volumes of all respective solutions. Basic instrumental set-up and extraction principles of μ-EME were examined using an anionic and a cationic dye, 4,5-dihydroxy-3-(p-sulfophenylazo)-2,7-naphthalene disulfonic acid trisodium salt (SPADNS) and crystal violet, respectively. Transfers of the charged dyes from donor into acceptor solutions across FLMs consisting of 1-pentanol were visualized by a microscope camera and quantitative measurements were performed by UV-vis spectrophotometry. The effects of operational parameters of μ-EME system were comprehensively investigated and experimental measurements were accompanied with theoretical calculations. Extraction recoveries above 60% were achieved for 5min μ-EME of 1mM SPADNS at 100V with repeatability values below 5%. Selectivity of FLMs was additionally examined by capillary electrophoretic analyses of acceptor solutions and the potential of FLMs for μ-EME pretreatment of samples with artificial complex matrices was demonstrated. Copyright © 2014 Elsevier B.V. All rights reserved.

A Collection of Target Mimics for Comprehensive Analysis of MicroRNA Function in Arabidopsis thaliana

PubMed Central

Paz-Ares, Javier; Weigel, Detlef

2010-01-01

Many targets of plant microRNAs (miRNAs) are thought to play important roles in plant physiology and development. However, because plant miRNAs are typically encoded by medium-size gene families, it has often been difficult to assess their precise function. We report the generation of a large-scale collection of knockdowns for Arabidopsis thaliana miRNA families; this has been achieved using artificial miRNA target mimics, a recently developed technique fashioned on an endogenous mechanism of miRNA regulation. Morphological defects in the aerial part were observed for ∼20% of analyzed families, all of which are deeply conserved in land plants. In addition, we find that non-cleavable mimic sites can confer translational regulation in cis. Phenotypes of plants expressing target mimics directed against miRNAs involved in development were in several cases consistent with previous reports on plants expressing miRNA–resistant forms of individual target genes, indicating that a limited number of targets mediates most effects of these miRNAs. That less conserved miRNAs rarely had obvious effects on plant morphology suggests that most of them do not affect fundamental aspects of development. In addition to insight into modes of miRNA action, this study provides an important resource for the study of miRNA function in plants. PMID:20661442

Numerical simulation and experimentation of adjusting the curvatures of micro-cantilevers using the water-confined laser-generated plasma

NASA Astrophysics Data System (ADS)

Gu, Chunxing; Shen, Zongbao; Liu, Huixia; Li, Pin; Lu, Mengmeng; Zhao, Yinxin; Wang, Xiao

2013-04-01

This paper describes a precise and non-contact adjustment technique using the water-confined laser-generated plasma to adjust the curvature of micro-components (micro-mechanical cantilevers). A series of laser shock micro-adjustment experiments were conducted on 0.4 mm-thick Al samples using pulsed Nd:YAG lasers operating at 1064 nm wavelengths to verify the technical feasibility. Systematic study was carried out in the term of effects of various factors on the adjusting results, including laser energies, laser focus positions, laser shock times and confined regime configuration. The research results have shown that the different bending angles and bending directions can be obtained by changing the laser processing parameters. And, for the adjustment process, the absence of confined regime configuration could also generate suitable bending deformation. But, in the case of larger energy, the final surfaces would have the sign of ablation, hence resulting in poor surface quality. An analysis procedure including dynamic analysis performed by ANSYS/LS-DYNA and static analysis performed by ANSYS is presented in detail to attain the simulation of laser shock micro-adjustment to predict the final bending deformation. The predicted bending profiles is well correlated with the available experimental data, showing the finite element analysis can predict the final curvatures of the micro-cantilevers properly.

Teachers, Micro-Credentials, and the Performance Assessment Movement

ERIC Educational Resources Information Center

French, Dan; Berry, Barnett

2017-01-01

Micro-credentials, a new form of personalized professional development for teachers, offer a unique solution to the challenge of training school staff to design and implement performance assessments. In a relatively short period of time, micro-credentials have shown promise in enabling a more personalized, effective method of promoting teacher…

Design of a small molecule against an oncogenic noncoding RNA.

PubMed

Velagapudi, Sai Pradeep; Cameron, Michael D; Haga, Christopher L; Rosenberg, Laura H; Lafitte, Marie; Duckett, Derek R; Phinney, Donald G; Disney, Matthew D

2016-05-24

The design of precision, preclinical therapeutics from sequence is difficult, but advances in this area, particularly those focused on rational design, could quickly transform the sequence of disease-causing gene products into lead modalities. Herein, we describe the use of Inforna, a computational approach that enables the rational design of small molecules targeting RNA to quickly provide a potent modulator of oncogenic microRNA-96 (miR-96). We mined the secondary structure of primary microRNA-96 (pri-miR-96) hairpin precursor against a database of RNA motif-small molecule interactions, which identified modules that bound RNA motifs nearby and in the Drosha processing site. Precise linking of these modules together provided Targaprimir-96 (3), which selectively modulates miR-96 production in cancer cells and triggers apoptosis. Importantly, the compound is ineffective on healthy breast cells, and exogenous overexpression of pri-miR-96 reduced compound potency in breast cancer cells. Chemical Cross-Linking and Isolation by Pull-Down (Chem-CLIP), a small-molecule RNA target validation approach, shows that 3 directly engages pri-miR-96 in breast cancer cells. In vivo, 3 has a favorable pharmacokinetic profile and decreases tumor burden in a mouse model of triple-negative breast cancer. Thus, rational design can quickly produce precision, in vivo bioactive lead small molecules against hard-to-treat cancers by targeting oncogenic noncoding RNAs, advancing a disease-to-gene-to-drug paradigm.

Straightforward and precise approach to replicate complex hierarchical structures from plant surfaces onto soft matter polymer

PubMed Central

Speck, Thomas; Bohn, Holger F.

2018-01-01

The surfaces of plant leaves are rarely smooth and often possess a species-specific micro- and/or nano-structuring. These structures usually influence the surface functionality of the leaves such as wettability, optical properties, friction and adhesion in insect–plant interactions. This work presents a simple, convenient, inexpensive and precise two-step micro-replication technique to transfer surface microstructures of plant leaves onto highly transparent soft polymer material. Leaves of three different plants with variable size (0.5–100 µm), shape and complexity (hierarchical levels) of their surface microstructures were selected as model bio-templates. A thermoset epoxy resin was used at ambient conditions to produce negative moulds directly from fresh plant leaves. An alkaline chemical treatment was established to remove the entirety of the leaf material from the cured negative epoxy mould when necessary, i.e. for highly complex hierarchical structures. Obtained moulds were filled up afterwards with low viscosity silicone elastomer (PDMS) to obtain positive surface replicas. Comparative scanning electron microscopy investigations (original plant leaves and replicated polymeric surfaces) reveal the high precision and versatility of this replication technique. This technique has promising future application for the development of bioinspired functional surfaces. Additionally, the fabricated polymer replicas provide a model to systematically investigate the structural key points of surface functionalities. PMID:29765666

Comparison study on disturbance estimation techniques in precise slow motion control

NASA Astrophysics Data System (ADS)

Fan, S.; Nagamune, R.; Altintas, Y.; Fan, D.; Zhang, Z.

2010-08-01

Precise low speed motion control is important for the industrial applications of both micro-milling machine tool feed drives and electro-optical tracking servo systems. It calls for precise position and instantaneous velocity measurement and disturbance, which involves direct drive motor force ripple, guide way friction and cutting force etc., estimation. This paper presents a comparison study on dynamic response and noise rejection performance of three existing disturbance estimation techniques, including the time-delayed estimators, the state augmented Kalman Filters and the conventional disturbance observers. The design technique essentials of these three disturbance estimators are introduced. For designing time-delayed estimators, it is proposed to substitute Kalman Filter for Luenberger state observer to improve noise suppression performance. The results show that the noise rejection performances of the state augmented Kalman Filters and the time-delayed estimators are much better than the conventional disturbance observers. These two estimators can give not only the estimation of the disturbance but also the low noise level estimations of position and instantaneous velocity. The bandwidth of the state augmented Kalman Filters is wider than the time-delayed estimators. In addition, the state augmented Kalman Filters can give unbiased estimations of the slow varying disturbance and the instantaneous velocity, while the time-delayed estimators can not. The simulation and experiment conducted on X axis of a 2.5-axis prototype micro milling machine are provided.

Localization algorithms for micro-channel x-ray telescope on board SVOM space mission

NASA Astrophysics Data System (ADS)

Gosset, L.; Götz, D.; Osborne, J.; Willingale, R.

2016-07-01

SVOM is a French-Chinese space mission to be launched in 2021, whose goal is the study of Gamma-Ray Bursts, the most powerful stellar explosions in the Universe. The Micro-channel X-ray Telescope (MXT) is an X-ray focusing telescope, on board SVOM, with a field of view of 1 degree (working in the 0.2-10 keV energy band), dedicated to the rapid follow-up of the Gamma-Ray Bursts counterparts and to their precise localization (smaller than 2 arc minutes). In order to reduce the optics mass and to have an angular resolution of few arc minutes, a "lobster-Eye" configuration has been chosen. Using a numerical model of the MXT Point Spread Function (PSF) we simulated MXT observations of point sources in order to develop and test different localization algorithms to be implemented on board MXT. We included preliminary estimations of the instrumental and sky background. The algorithms on board have to be a combination of speed and precision (the brightest sources are expected to be localized at a precision better than 10 arc seconds in the MXT reference frame). We present the comparison between different methods such as barycentre, PSF fitting in one or two dimensions. The temporal performance of the algorithms is being tested using the X-ray afterglow data base of the XRT telescope on board the NASA Swift satellite.

Characteristics of digital micromirror projection for 3D shape measurement at extreme speed

NASA Astrophysics Data System (ADS)

Höfling, Roland; Aswendt, Petra; Leischnig, Frank; Förster, Matthias

2015-03-01

3D shape measurement is one of the growing industrial applications of the Texas Instruments DLP® micro-mirror device. This paper presents investigations on precision and repeatability of that spatial light modulators output when it is driven up to its high-speed limit. The study concerns the basic switching behavior of the individual micro-mirror at different frame rates ranging over three orders of magnitude. The 3D shape measuring methodologies are focused on phase encoded triangulation, i.e. the projection of sinusoidal patterns. The DLP chip is a bi-stable device providing an on/off pattern at each certain moment in time, i.e. it has a native binary output. Sinusoidal patterns are the result of either a temporal integration of multiple on/off patterns or a spatial integration within one on/off pattern. Both approaches are studied experimentally with respect to precision and stability of the pattern output. The STAR-07 industrial projection unit, based upon the 0.7" DLP Discovery™4100 chipset, has been used for this work and the pattern frame rates cover the range from 225 frames per second (fps) to 50,000 fps. The STAR-07 output is detected by a photodiode, amplified, and analyzed in a Yokogawa digital storage oscilloscope. All results prove the very high precision and repeatability of the STAR-07 pattern projection, up to the extreme speed of 50,000 fps.

A quality assurance phantom for the performance evaluation of volumetric micro-CT systems

NASA Astrophysics Data System (ADS)

Du, Louise Y.; Umoh, Joseph; Nikolov, Hristo N.; Pollmann, Steven I.; Lee, Ting-Yim; Holdsworth, David W.

2007-12-01

Small-animal imaging has recently become an area of increased interest because more human diseases can be modeled in transgenic and knockout rodents. As a result, micro-computed tomography (micro-CT) systems are becoming more common in research laboratories, due to their ability to achieve spatial resolution as high as 10 µm, giving highly detailed anatomical information. Most recently, a volumetric cone-beam micro-CT system using a flat-panel detector (eXplore Ultra, GE Healthcare, London, ON) has been developed that combines the high resolution of micro-CT and the fast scanning speed of clinical CT, so that dynamic perfusion imaging can be performed in mice and rats, providing functional physiological information in addition to anatomical information. This and other commercially available micro-CT systems all promise to deliver precise and accurate high-resolution measurements in small animals. However, no comprehensive quality assurance phantom has been developed to evaluate the performance of these micro-CT systems on a routine basis. We have designed and fabricated a single comprehensive device for the purpose of performance evaluation of micro-CT systems. This quality assurance phantom was applied to assess multiple image-quality parameters of a current flat-panel cone-beam micro-CT system accurately and quantitatively, in terms of spatial resolution, geometric accuracy, CT number accuracy, linearity, noise and image uniformity. Our investigations show that 3D images can be obtained with a limiting spatial resolution of 2.5 mm-1 and noise of ±35 HU, using an acquisition interval of 8 s at an entrance dose of 6.4 cGy.

Contactless and non-invasive delivery of micro-particles lying on a non-customized rigid surface by using acoustic radiation force.

PubMed

Meng, Jianxin; Mei, Deqing; Jia, Kun; Fan, Zongwei; Yang, Keji

2014-07-01

In the existing acoustic micro-particle delivery methods, the micro-particles always lie and slide on the surface of platform in the whole delivery process. To avoid the damage and contamination of micro-particles caused by the sliding motion, this paper deals with a novel approach to trap micro-particles from non-customized rigid surfaces and freely manipulate them. The delivery process contains three procedures: detaching, transporting, and landing. Hence, the micro-particles no longer lie on the surface, but are levitated in the fluid, during the long range transporting procedure. It is very meaningful especially for the fragile and easily contaminated targets. To quantitatively analyze the delivery process, a theoretical model to calculate the acoustic radiation force exerting upon a micro-particle near the boundary in half space is built. An experimental device is also developed to validate the delivery method. A 100 μm diameter micro-silica bead adopted as the delivery target is detached from the upper surface of an aluminum platform and levitated in the fluid. Then, it is transported along the designated path with high precision in horizontal plane. The maximum deviation is only about 3.3 μm. During the horizontal transportation, the levitation of the micro-silica bead is stable, the maximum fluctuation is less than 1 μm. The proposed method may extend the application of acoustic radiation force and provide a promising tool for microstructure or cell manipulation. Copyright © 2014 Elsevier B.V. All rights reserved.

SmallSat Precision Navigation with Low-Cost MEMS IMU Swarms

NASA Technical Reports Server (NTRS)

Christian, John; Bishop, Robert; Martinez, Andres; Petro, Andrew

2015-01-01

The continued advancement of small satellite-based science missions requires the solution to a number of important technical challenges. Of particular note is that small satellite missions are characterized by tight constraints on cost, mass, power, and volume that make them unable to fly the high-quality Inertial Measurement Units (IMUs) required for orbital missions demanding precise orientation and positioning. Instead, small satellite missions typically fly low-cost Micro-Electro-Mechanical System (MEMS) IMUs. Unfortunately, the performance characteristics of these MEMS IMUs make them ineffectual in many spaceflight applications when employed in a single IMU system configuration.

Research of vacuum polymer film on three-dimension surface (Conference Presentation)

NASA Astrophysics Data System (ADS)

Bau, Yung-Han

2016-09-01

This study focused on UV-curable acrylic hybrid of solute in vacuum-deposited on the surface and make it smooth. On the surface coating of the entire process, including the pre-treatment of organic solutes, vacuum, nozzle pressure, airflow, frequency ratio, the surface of the rotation rate, nozzle angle, UV light irradiation time, waste solute recycling.Organic solutes through a flow meter and precise measured,by high pressure or vibration of a piezoelectric material, spray our organic solute in a certain degree of vacuum,leaving nozzle of tiny micro-mist volatiles in a vacuum to form secondary atomization,deposited our surface,Since no UV light irradiation, the surface is a liquid having fluidity, so the non-planar substrates can have good performance, finally it is irradiated by UV light of sufficient energy solidify to form a solid film.The advantage of this approach is that a smooth surface,Strong adhesion, low-cost equipment, low temperature, a wide range of high deposition rate can be combined with other deposition method,Under vacuum have not waste because excess paint can be recycled.Avoid solute direct contact with human, relative to the environment-friendly.

Application of micro- and nanocrystalline cellulose

NASA Astrophysics Data System (ADS)

Sotnikova, Yu S.; Demina, T. S.; Istomin, A. V.; Goncharuk, G. P.; Grandfils, Ch; Akopova, T. A.; Zelenetskii, A. N.; Babayevsky, P. G.

2018-04-01

Micro- and nanocrystalline forms of cellulose were extracted from flax stalks and evaluated in terms of their applicability for various materials science tasks. It was revealed that both form of cellulose had anisometric morphology with length of 27.1 μm and 159 nm; diameter of 8.7 μm and 85 nm, respectively. They were used as reinforcing fillers for fabrication of composite films based on hydroxyethylcellulose. Film-forming and mechanical properties of the composite materials were significantly varied in dependence on filler content (0–10 wt.%) and size. As a second option of micro- and nanocrystalline cellulose application, a study of their effectiveness as stabilizing agents for oil/water Pickering emulsions was carried out. In contrast to micron-sized cellulose the nanocrystalline form appeared to be successful in the process of CH2Cl2/water interface stabilization and fabrication of polylactide microparticles via oil/water Pickering emulsion solvent evaporation technique.

Application of SPM interferometry in MEMS vibration measurement

NASA Astrophysics Data System (ADS)

Tang, Chaowei; He, Guotian; Xu, Changbiao; Zhao, Lijuan; Hu, Jun

2007-12-01

The resonant frequency measurement of cantilever has an important position in MEMS(Micro Electro Mechanical Systems) research. Meanwhile the SPM interferometry is a high-precision optical measurement technique, which can be used in physical quantity measurement of vibration, displacement, surface profile. Hence, in this paper we propose to apply SPM(SPM) interferometry in measuring the vibration of MEMS cantilever and in the experiment the vibration of MEMS cantilever was driven by light source. Then this kind of vibration was measured in nm precision. Finally the relational characteristics of MEMS cantilever vibration under optical excitation can be gotten and the measurement principle is analyzed. This method eliminates the influence on the measuring precision caused by external interference and light intensity change through feedback control loop. Experiment results prove that this measurement method has a good effect.

Effects of PCB Pad Metal Finishes on the Cu-Pillar/Sn-Ag Micro Bump Joint Reliability of Chip-on-Board (COB) Assembly

NASA Astrophysics Data System (ADS)

Kim, Youngsoon; Lee, Seyong; Shin, Ji-won; Paik, Kyung-Wook

2016-06-01

While solder bumps have been used as the bump structure to form the interconnection during the last few decades, the continuing scaling down of devices has led to a change in the bump structure to Cu-pillar/Sn-Ag micro-bumps. Cu-pillar/Sn-Ag micro-bump interconnections differ from conventional solder bump interconnections in terms of their assembly processing and reliability. A thermo-compression bonding method with pre-applied b-stage non-conductive films has been adopted to form solder joints between Cu pillar/Sn-Ag micro bumps and printed circuit board vehicles, using various pad metal finishes. As a result, various interfacial inter-metallic compounds (IMCs) reactions and stress concentrations occur at the Cu pillar/Sn-Ag micro bumps joints. Therefore, it is necessary to investigate the influence of pad metal finishes on the structural reliability of fine pitch Cu pillar/Sn-Ag micro bumps flip chip packaging. In this study, four different pad surface finishes (Thin Ni ENEPIG, OSP, ENEPIG, ENIG) were evaluated in terms of their interconnection reliability by thermal cycle (T/C) test up to 2000 cycles at temperatures ranging from -55°C to 125°C and high-temperature storage test up to 1000 h at 150°C. The contact resistances of the Cu pillar/Sn-Ag micro bump showed significant differences after the T/C reliability test in the following order: thin Ni ENEPIG > OSP > ENEPIG where the thin Ni ENEPIG pad metal finish provided the best Cu pillar/Sn-Ag micro bump interconnection in terms of bump joint reliability. Various IMCs formed between the bump joint areas can account for the main failure mechanism.

Fabrication of micro T-shaped tubular components by hydroforming process

NASA Astrophysics Data System (ADS)

Manabe, Ken-ichi; Itai, Kenta; Tada, Kazuo

2017-10-01

This paper deals with a T-shape micro tube hydroforming (MTHF) process for 500 µm outer diameter copper microtube. The MTHF experiments were carried out using a MTHF system utilizing ultrahigh pressure. The fundamental micro hydroforming characteristics as well as forming limits are examined experimentally and numerically. From the results, a process window diagram for micro T-shape hydroforming process is created, and a suitable "success" region is revealed.

Micro-engineered remote palpation device for assessing tissue compliance.

PubMed

Hien, M; Yang, T H J; Leung, S K W; Reuben, R L; Habib, F K; McNeill, S A; Schneider, A; McBride, G; Stevens, R; Else, R W

2008-01-01

This paper concerns the operation of the actuator for a prototype micro-engineered mechanical palpation device for deployment via a cystoscope to measure the dynamic mechanical properties of the prostate gland in vivo. The subassembly consists of a 400x200 microm silicon (Si) piston manufactured using deep reactive ion etching (DRIE) housed within an anodically bonded glass-Si-glass sandwiched housing. The micro-channel on the Si layer was formed by powder blasting and contains the micro-piston with one end pointing to the side of the housing and the other facing a via hole leading to a capillary tube. The opening on the side of the housing was sealed by a 5 microm thick silicone membrane which acts to retain the micro-piston and act as a return spring. A 320 microm diameter capillary forms the connection between the micro-channel and a micro-syringe which is operated by a programmable syringe pump to produce a reciprocating action. A pressure sensor is connected along the capillary tube to measure the dynamic pressure within the system. The micro-piston has already been used, separately actuated to measure the dynamic mechanical properties of known viscoelastic materials and prostate tissue. The purpose of the present work is to assess the functionality of the actuator assembly.

Stability and Behaviors of Methane/Propane and Hydrogen Micro Flames

NASA Astrophysics Data System (ADS)

Yoshimoto, Takamitsu; Kinoshita, Koichiro; Kitamura, Hideki; Tanigawa, Ryoichi

The flame stability limits essentially define the fundamental operation of the combustion system. Recently the micro diffusion flame has been remarked. The critical conditions of the flame stability limit are highly dependent on nozzle diameter, species of fuel and so on. The micro diffusion flame of Methane/Propane and Hydrogen is formed by using the micro-scale nozzle of which inner diameter is less than 1mm. The configurations and behaviors of the flame are observed directly and visualized by the high speed video camera The criteria of stability limits are proposed for the micro diffusion flame. The objectives of the present study are to get further understanding of lifting/blow-off for the micro diffusion flame. The results obtained are as follows. (1) The behaviors of the flames are classified into some regions for each diffusion flame. (2) The micro diffusion flame of Methane/Propane cannot be sustained, when the nozzle diameter is less than 0.14 mm. (3) The diffusion flame cannot be sustained below the critical fuel flow rate. (4) The minimum flow which is formed does not depends on the average jet velocity, but on the fuel flow rate. (5) the micro flame is laminar. The flame length is decided by fuel flow rate.

High resolution laser micro sintering / melting using q-switched and high brilliant laser radiation

NASA Astrophysics Data System (ADS)

Exner, H.; Streek, A.

2015-03-01

Since the discovery of selective laser sintering/melting, numerous modifications have been made to upgrade or customize this technology for industrial purposes. Laser micro sintering (LMS) is one of those modifications: Powders with particles in the range of a few micrometers are used to obtain products with highly resolved structures. Pulses of a q-switched laser had been considered necessary in order to generate sinter layers from the micrometer scaled metal powders. LMS has been applied with powders from metals as well as from ceramic and cermet feedstock's to generate micro parts. Recent technological progress and the application of high brilliant continuous laser radiation have now allowed an efficient laser sintering/melting of micrometer scaled metal powders. Thereby it is remarkable that thin sinter layers are generated using high continuous laser power. The principles of the process, the state of the art in LMS concerning its advantages and limitations and furthermore the latest results of the recent development of this technology will be presented. Laser Micro Sintering / Laser Micro Melting (LMM) offer a vision for a new dimension of additive fabrication of miniature and precise parts also with application potential in all engineering fields.

Direct hierarchical assembly of nanoparticles

DOEpatents

Xu, Ting; Zhao, Yue; Thorkelsson, Kari

2014-07-22

The present invention provides hierarchical assemblies of a block copolymer, a bifunctional linking compound and a nanoparticle. The block copolymers form one micro-domain and the nanoparticles another micro-domain.

A cryogenic tensile testing apparatus for micro-samples cooled by miniature pulse tube cryocooler

NASA Astrophysics Data System (ADS)

Chen, L. B.; Liu, S. X.; Gu, K. X.; Zhou, Y.; Wang, J. J.

2015-12-01

This paper introduces a cryogenic tensile testing apparatus for micro-samples cooled by a miniature pulse tube cryocooler. At present, tensile tests are widely applied to measure the mechanical properties of materials; most of the cryogenic tensile testing apparatus are designed for samples with standard sizes, while for non-standard size samples, especially for microsamples, the tensile testing cannot be conducted. The general approach to cool down the specimens for tensile testing is by using of liquid nitrogen or liquid helium, which is not convenient: it is difficult to keep the temperature of the specimens at an arbitrary set point precisely, besides, in some occasions, liquid nitrogen, especially liquid helium, is not easily available. To overcome these limitations, a cryogenic tensile testing apparatus cooled by a high frequency pulse tube cryocooler has been designed, built and tested. The operating temperatures of the developed tensile testing apparatus cover from 20 K to room temperature with a controlling precision of ±10 mK. The apparatus configurations, the methods of operation and some cooling performance will be described in this paper.

High-resolution Identification and Separation of Living Cell Types by Multiple microRNA-responsive Synthetic mRNAs.

PubMed

Endo, Kei; Hayashi, Karin; Saito, Hirohide

2016-02-23

The precise identification and separation of living cell types is critical to both study cell function and prepare cells for medical applications. However, intracellular information to distinguish live cells remains largely inaccessible. Here, we develop a method for high-resolution identification and separation of cell types by quantifying multiple microRNA (miRNA) activities in live cell populations. We found that a set of miRNA-responsive, in vitro synthesized mRNAs identify a specific cell population as a sharp peak and clearly separate different cell types based on less than two-fold differences in miRNA activities. Increasing the number of miRNA-responsive mRNAs enhanced the capability for cell identification and separation, as we precisely and simultaneously distinguished different cell types with similar miRNA profiles. In addition, the set of synthetic mRNAs separated HeLa cells into subgroups, uncovering heterogeneity of the cells and the level of resolution achievable. Our method could identify target live cells and improve the efficiency of cell purification from heterogeneous populations.

Automated GC-MS analysis of free amino acids in biological fluids.

PubMed

Kaspar, Hannelore; Dettmer, Katja; Gronwald, Wolfram; Oefner, Peter J

2008-07-15

A gas chromatography-mass spectrometry (GC-MS) method was developed for the quantitative analysis of free amino acids as their propyl chloroformate derivatives in biological fluids. Derivatization with propyl chloroformate is carried out directly in the biological samples without prior protein precipitation or solid-phase extraction of the amino acids, thereby allowing automation of the entire procedure, including addition of reagents, extraction and injection into the GC-MS. The total analysis time was 30 min and 30 amino acids could be reliably quantified using 19 stable isotope-labeled amino acids as internal standards. Limits of detection (LOD) and lower limits of quantification (LLOQ) were in the range of 0.03-12 microM and 0.3-30 microM, respectively. The method was validated using a certified amino acid standard and reference plasma, and its applicability to different biological fluids was shown. Intra-day precision for the analysis of human urine, blood plasma, and cell culture medium was 2.0-8.8%, 0.9-8.3%, and 2.0-14.3%, respectively, while the inter-day precision for human urine was 1.5-14.1%.

Finite element analysis of displacement actuator based on giant magnetostrictive thin film

NASA Astrophysics Data System (ADS)

Yu, Shaopeng; Wang, Bowen; Zhang, Changgeng; Cui, Baozhi

2018-05-01

With the rapid development of science and technology, mechanical and electrical equipment become more and more miniature. In order to achieve precise control in less than 1cm3, the giant magnetostrictive thin film has become a research hotspot. The micro displacement actuator with planar and arc film is designed by the dynamic coupling model based on J-A model and magneto-mechanical effect method which is proposed in this paper. The different structure and thickness of films are analyzed by COMSOL Multiphysics software when the current flows through driving coil. After comparing the simulation results with the test ones, it can be seen that the coupling model is accurate and the structure is reliable. At the same time, MATLAB is used to fit the current density-displacement curve and higher order equation is obtained, and then the feasibility of design can be verified. The actuator with arc structure had advantages of small volume, fast response, high precision, easy integration, etc., which has a broad application prospect in the field of vibration control, micro positioning, robot and so on.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luo, Shaohua; School of Automation, Chongqing University, Chongqing 400044; Sun, Quanping

This paper addresses chaos control of the micro-electro- mechanical resonator by using adaptive dynamic surface technology with extended state observer. To reveal the mechanism of the micro- electro-mechanical resonator, the phase diagrams and corresponding time histories are given to research the nonlinear dynamics and chaotic behavior, and Homoclinic and heteroclinic chaos which relate closely with the appearance of chaos are presented based on the potential function. To eliminate the effect of chaos, an adaptive dynamic surface control scheme with extended state observer is designed to convert random motion into regular motion without precise system model parameters and measured variables. Puttingmore » tracking differentiator into chaos controller solves the ‘explosion of complexity’ of backstepping and poor precision of the first-order filters. Meanwhile, to obtain high performance, a neural network with adaptive law is employed to approximate unknown nonlinear function in the process of controller design. The boundedness of all the signals of the closed-loop system is proved in theoretical analysis. Finally, numerical simulations are executed and extensive results illustrate effectiveness and robustness of the proposed scheme.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ingebretsen, O.C.; Borgen, J.; Farstad, M.

A reversed-phase liquid-chromatographic procedure is presented for quantitation or uric acid in human serum, with absorbance measured at 292 nm. The mobile phase was sodium acetate (35 mmol/L, pH 5.0)/acetonitrile (9/1 by vol). Complete precipitation of serum proteins was obtained by mixing serum (50-500 microL) with an equal volume of acetonitrile, and the precipitate was removed by centrifugation. Aliquots (20 microL) of the supernate were injected directly into the liquid chromatograph, which was adjusted so that the absorbance reading of the uric acid peak was as high as possible. Routinely, a full-scale deflection of 1.28 absorbance units was used. Themore » within-run precision (CV) was 0.6% for a serum uric acid concentration of 227 mumol/L and day-to-day precision over a 15-day period was 0.8% for uric acid of 345 mumol/L. No interferences from related compounds were observed. Researchers compared results by this method with those by kinetic and equilibrium adaptations of uricase methods. The method reported is simple, and can be used in a fully automatic liquid-chromatographic system.« less

Precision optical device of freeform defects inspection

NASA Astrophysics Data System (ADS)

Meguellati, S.

2015-09-01

This method of optical scanning presented in this paper is used for precision measurement deformation in shape or absolute forms in comparison with a reference component form, of optical or mechanical components, on reduced surfaces area that are of the order of some mm2 and more. The principle of the method is to project the image of the source grating to palpate optically surface to be inspected, after reflection; the image of the source grating is printed by the object topography and is then projected onto the plane of reference grating for generate moiré fringe for defects detection. The optical device used allows a significant dimensional surface magnification of up to 1000 times the area inspected for micro-surfaces, which allows easy processing and reaches an exceptional nanometric imprecision of measurements. According to the measurement principle, the sensitivity for displacement measurement using moiré technique depends on the frequency grating, for increase the detection resolution. This measurement technique can be used advantageously to measure the deformations generated by the production process or constraints on functional parts and the influence of these variations on the function. The optical device and optical principle, on which it is based, can be used for automated inspection of industrially produced goods. It can also be used for dimensional control when, for example, to quantify the error as to whether a piece is good or rubbish. It then suffices to compare a figure of moiré fringes with another previously recorded from a piece considered standard; which saves time, money and accuracy. The technique has found various applications in diverse fields, from biomedical to industrial and scientific applications.

Determination of pKa values of benzoxa-, benzothia- and benzoselena-zolinone derivatives by capillary electrophoresis. Comparison with potentiometric titration and spectrometric data.

PubMed

Foulon, C; Duhal, N; Lacroix-Callens, B; Vaccher, C; Bonte, J P; Goossens, J F

2007-07-01

Acidity constants of benzoxa-, benzothia- and benzoselena-zolinone derivatives were determined by capillary electrophoresis, potentiometry and spectrophotometry experiments. These three analytical techniques gave pK(a) results that were in good agreement. A convenient, accurate and precise method for the determination of pK(a) was developed to measure changes in acidity constants induced by heteroatom or 6-benzoyl substituted derivatives. pK(a) values were determined simultaneously for two compounds characterized by different electrophoretic mobility (micro(e)) and pK(a) value and in the presence of an analogous neutral marker.

A SEA FLOOR GRAVITY SURVEY OF THE SLEIPNER FIELD TO MONITOR CO2 MIGATION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mark Zumberge

2003-06-13

At the Sleipner gas field, excess CO{sub 2} is sequestered and injected underground into a porous saline aquifer 1000 m below the seafloor. A high precision micro-gravity survey was carried out on the seafloor to monitor the injected CO{sub 2}. A repeatability of 5 {micro}Gal in the station averages was observed. This is considerably better than pre-survey expectations. These data will serve as the baseline for time-lapse gravity monitoring of the Sleipner CO{sub 2} injection site. Simple modeling of the first year data give inconclusive results, thus a more detailed approach is needed. Work towards this is underway.

Active depth-guiding handheld micro-forceps for membranectomy based on CP-SSOCT

NASA Astrophysics Data System (ADS)

Cheon, Gyeong Woo; Lee, Phillip; Gonenc, Berk; Gehlbach, Peter L.; Kang, Jin U.

2016-03-01

In this study, we demonstrate a handheld motion-compensated micro-forceps system using common-path swept source optical coherence tomography with highly accurate depth-targeting and depth-locking for Epiretinal Membrane Peeling. Two motors and a touch sensor were used to separate the two independent motions: motion compensation and tool-tip manipulation. A smart motion monitoring and guiding algorithm was devised for precise and intuitive freehand control. Ex-vivo bovine eye experiments were performed to evaluate accuracy in a bovine retina retinal membrane peeling model. The evaluation demonstrates system capabilities of 40 um accuracy when peeling the epithelial layer of bovine retina.

Micro-Dose Calibrator for Pre-clinical Radiotracer Assays | NCI Technology Transfer Center | TTC

Cancer.gov

Pre-clinical radiotracer biomedical research involves the use of compounds labeled with radioisotopes, including cell binding studies, immune cell labeling techniques, and radio-ligand bio-distribution studies. Before this Micro-Dose Calibrator, measurement of pre-clinical level dosage for small animal studies was inaccurate and unreliable. This dose calibrator is a prototype ready for manufacturing. It is designed to accurately measure radioactive doses in the range of 50 nCi (1.8 kBq) to 100 µCi (3.7 MBq) with 1% precision. The NCI seeks co-development or licensing to commercialize it. Alternative uses will be considered.

Micro-telerobotic applications for microsurgery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ford, W.E.; Morimoto, A.K.; Kozlowski, D.M.

MicroDexterity Systems Inc. and Sandia National Laboratories are collaborating on the design of a six degree-of-freedom surgeon-controlled micropositioner and a six degree-of-freedom surgeon-controlled master for use in microsurgery. A control system will provide the linkage between the force-reflecting master and micropositioner for force scaling, position scaling, and tremor filtering. The technologies developed by this project are expected to enhance the skills of surgeons, improve the success rates for existing microsurgical procedures, make new high-dexterity procedures possible, and ultimately reduce surgical costs by increasing the precision and speed of operations. This paper discusses the motivation, approach, and accomplishments to date.

Role of selective cyclic GMP phosphodiesterase inhibition in the myorelaxant actions of M&B 22,948, MY-5445, vinpocetine and 1-methyl-3-isobutyl-8-(methylamino)xanthine.

PubMed Central

Souness, J. E.; Brazdil, R.; Diocee, B. K.; Jordan, R.

1989-01-01

1. The mechanism by which M&B 22,948, MY-5445, vinpocetine and 1-methyl-3-isobutyl-8-(methylamino)xanthine (MIMAX), which have been described as selective cyclic GMP phosphodiesterase (PDE) inhibitors, relax rat aorta was investigated. 2. Three cyclic nucleotide PDEs were identified in the soluble fraction of rat aorta; a Ca2+-insensitive form exhibiting substrate selectivity for cyclic GMP (cGMP PDE), a Ca2+/calmodulin-stimulated form which also preferentially hydrolyzed cyclic GMP (Ca2+ PDE), and a form demonstrating substrate selectivity for cyclic AMP (cAMP PDE). 3. M&B 22,948 and MIMAX inhibited cGMP PDE (Ki = 0.16 microM and 0.43 microM, respectively) and Ca2+ PDE (Ki = 9.9 microM and 0.55 microM, respectively), but exhibited weak activity against cAMP PDE (Ki = 249 microM and 42 microM, respectively). MY-5445 selectivity inhibited cGMP PDE (Ki = 1.3 microM) and vinpocetine selectively inhibited Ca2+ PDE (Ki = 14 microM). 4. M&B 22,948 and MIMAX induced dose-dependent increases in the accumulation of cyclic GMP, but not cyclic AMP, in rat aorta pieces. These effects were greatly reduced by endothelial denudation and by methylene blue (5 microM) which blocks the actions of endothelium-derived relaxant factor. MY-5445 and vinpocetine had no effect on rat aorta cyclic GMP or cyclic AMP accumulation. 5. All four compounds caused dose-related relaxation of 5-hydroxytryptamine (10 microM) contracted, endothelium-intact rat aorta, the effects of M&B 22,948 and MIMAX being greatly reduced by methylene blue (5 microM). Methylene blue also caused 10 fold and 100 fold rightward shifts in the dose-response curves of MY-5445 and vinpocetine, respectively. 6. The results are consistent with the smooth muscle relaxant actions of M&B 22,948 and MIMAX, but not vinpocetine and MY-5445, being mediated through a mechanism involving inhibition of cyclic GMP hydrolysis. PMID:2480168

Micro and nano liposome vesicles containing curcumin for a drug delivery system

NASA Astrophysics Data System (ADS)

Nguyen, Tuan Anh; Duoc Tang, Quan; Chanh Tin Doan, Duc; Chien Dang, Mau

2016-09-01

Micro and nano liposome vesicles were prepared using a lipid film hydration method and a sonication method. Phospholipid, cholesterol and curcumin were used to form micro and nano liposomes containing curcumin. The size, structure and properties of the liposomes were characterized by using optical microscopy, transmission electron microscopy, and UV-vis and Raman spectroscopy. It was found that the size of the liposomes was dependent on their composition and the preparation method. The hydration method created micro multilamellars, whereas nano unilamellars were formed using the sonication method. By adding cholesterol, the vesicles of the liposome could be stabilized and stored at 4 °C for up to 9 months. The liposome vesicles containing curcumin with good biocompatibility and biodegradability could be used for drug delivery applications.

A bio-physical basis of mathematics in synaptic function of the nervous system: a theory.

PubMed

Dempsher, J

1980-01-01

The purpose of this paper is to present a bio-physical basis of mathematics. The essence of the theory is that function in the nervous system is mathematical. The mathematics arises as a result of the interaction of energy (a wave with a precise curvature in space and time) and matter (a molecular or ionic structure with a precise form in space and time). In this interaction, both energy and matter play an active role. That is, the interaction results in a change in form of both energy and matter. There are at least six mathematical operations in a simple synaptic region. It is believed the form of both energy and matter are specific, and their interaction is specific, that is, function in most of the 'mind' and placed where it belongs - in nature and the synaptic regions of the nervous system; it results in both places from a precise interaction between energy (in a precise form) and matter ( in a precise structure).

Development of a low-cost mini environment chamber for precision instruments

NASA Astrophysics Data System (ADS)

Feng, Jian; Li, Rui-Jun; He, Ya-Xiong; Fan, Kuang-Chao

2016-01-01

The wavelength of laser interferometer used widely in precision measurement instrument is affected by the refractive index of surrounding air, which depends on the temperature, relative humidity (RH) and air pressure. A low-cost mini chamber based on the natural convection principle with high-precision temperature-controlled and humidity-suppressed is proposed in this paper. The main chamber is built up by acrylic walls supported by aluminum beam column and are tailored according to the required space. A thin layer of vacuum insulation panel (VIP) with an ultralow thermal conductivity coefficient is adhered around the walls so as to prevent heat exchange with room air. A high-precision temperature sensor measuring the temperature near the instrument's measuring point provides a feedback signal to a proportional-integral-derivative (PID) controller. Several thermoelectric coolers uniformly arranged on the ceiling of the chamber to cool the air inside the chamber directly without any air supply system, yielding a vibration-free cooling system. A programmable power supply is used as the driver for the coolers to generate different cooling capacities. The down-flowing cool air and the up-flowing hot air form a natural convection, and the air temperature in the chamber gradually becomes stable and finally reaches the temperature set by the PID controller. Recycled desiccant contained silica gels that have high affinity for water is used as a drying agent. Experimental results show that in about two hours the system's steady state error is 0.003°C on average, and the variation range is less than ± 0.02°C when the set temperature is 20°C, the RH is reduced from 66% to about 48%. This innovative mini chamber has the advantages of low-cost, vibration-free, and low energy-consumption. It can be used for any micro/nanomeasurement instrument and its volume can be customer-designed.

Precision injection molding of freeform optics

NASA Astrophysics Data System (ADS)

Fang, Fengzhou; Zhang, Nan; Zhang, Xiaodong

2016-08-01

Precision injection molding is the most efficient mass production technology for manufacturing plastic optics. Applications of plastic optics in field of imaging, illumination, and concentration demonstrate a variety of complex surface forms, developing from conventional plano and spherical surfaces to aspheric and freeform surfaces. It requires high optical quality with high form accuracy and lower residual stresses, which challenges both optical tool inserts machining and precision injection molding process. The present paper reviews recent progress in mold tool machining and precision injection molding, with more emphasis on precision injection molding. The challenges and future development trend are also discussed.

Fine-grained information extraction from German transthoracic echocardiography reports.

PubMed

Toepfer, Martin; Corovic, Hamo; Fette, Georg; Klügl, Peter; Störk, Stefan; Puppe, Frank

2015-11-12

Information extraction techniques that get structured representations out of unstructured data make a large amount of clinically relevant information about patients accessible for semantic applications. These methods typically rely on standardized terminologies that guide this process. Many languages and clinical domains, however, lack appropriate resources and tools, as well as evaluations of their applications, especially if detailed conceptualizations of the domain are required. For instance, German transthoracic echocardiography reports have not been targeted sufficiently before, despite of their importance for clinical trials. This work therefore aimed at development and evaluation of an information extraction component with a fine-grained terminology that enables to recognize almost all relevant information stated in German transthoracic echocardiography reports at the University Hospital of Würzburg. A domain expert validated and iteratively refined an automatically inferred base terminology. The terminology was used by an ontology-driven information extraction system that outputs attribute value pairs. The final component has been mapped to the central elements of a standardized terminology, and it has been evaluated according to documents with different layouts. The final system achieved state-of-the-art precision (micro average.996) and recall (micro average.961) on 100 test documents that represent more than 90 % of all reports. In particular, principal aspects as defined in a standardized external terminology were recognized with f 1=.989 (micro average) and f 1=.963 (macro average). As a result of keyword matching and restraint concept extraction, the system obtained high precision also on unstructured or exceptionally short documents, and documents with uncommon layout. The developed terminology and the proposed information extraction system allow to extract fine-grained information from German semi-structured transthoracic echocardiography reports with very high precision and high recall on the majority of documents at the University Hospital of Würzburg. Extracted results populate a clinical data warehouse which supports clinical research.

Sub-microradian Surface Slope Metrology with the ALS Developmental Long Trace Profiler

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yashchuk, Valeriy V.; Barber, Samuel; Domning, Edward E.

2009-06-15

Development of X-ray optics for 3rd and 4th generation X-ray light sources with a level of surface slope precision of 0.1-0.2 {micro}rad requires the development of adequate fabrication technologies and dedicated metrology instrumentation and methods. Currently, the best performance of surface slope measurement has been achieved with the NOM (Nanometer Optical Component Measuring Machine) slope profiler at BESSY (Germany) [1] and the ESAD (Extended Shear Angle Difference) profiler at the PTB (Germany) [2]. Both instruments are based on electronic autocollimators (AC) precisely calibrated for the specific application [3] with small apertures of 2.5-5 mm in diameter. In the present work,more » we describe the design, initial alignment and calibration procedures, the instrumental control and data acquisition system, as well as the measurement performance of the Developmental Long Trace Profiler (DLTP) slope measuring instrument recently brought into operation at the Advanced Light Source (ALS) Optical Metrology Laboratory (OML). Similar to the NOM and ESAD, the DLTP is based on a precisely calibrated autocollimator. However, this is a reasonably low budget instrument used at the ALS OML for the development and testing of new measuring techniques and methods. Some of the developed methods have been implemented into the ALS LTP-II (slope measuring long trace profiler [4]) which was recently upgraded and has demonstrated a capability for 0.25 {micro}rad surface metrology [5]. Performance of the DLTP was verified via a number of measurements with high quality reference mirrors. A comparison with the corresponding results obtained with the world's best slope measuring instrument, the BESSY NOM, proves the accuracy of the DLTP measurements on the level of 0.1-0.2 {micro}rad depending on the curvature of a surface under test. The directions of future work to develop a surface slope measuring profiler with nano-radian performance are also discussed.« less

Acoustic trapping in bubble-bounded micro-cavities

NASA Astrophysics Data System (ADS)

O'Mahoney, P.; McDougall, C.; Glynne-Jones, P.; MacDonald, M. P.

2016-12-01

We present a method for controllably producing longitudinal acoustic trapping sites inside microfluidic channels. Air bubbles are injected into a micro-capillary to create bubble-bounded `micro-cavities'. A cavity mode is formed that shows controlled longitudinal acoustic trapping between the two air/water interfaces along with the levitation to the centre of the channel that one would expect from a lower order lateral mode. 7 μm and 10 μm microspheres are trapped at the discrete acoustic trapping sites in these micro-cavities.We show this for several lengths of micro-cavity.

Development and calibration of an air-floating six-axis force measurement platform using self-calibration

NASA Astrophysics Data System (ADS)

Huang, Bin; Wang, Xiaomeng; Li, Chengwei; Yi, Jiajing; Lu, Rongsheng; Tao, Jiayue

2016-09-01

This paper describes the design, working principle, as well as calibration of an air-floating six-axis force measurement platform, where the floating plate and nozzles were connected without contact, preventing inter-dimensional coupling and increasing precision significantly. The measurement repeatability error of the force size in the platform is less than 0.2% full scale (FS), which is significantly better than the precision of 1% FS in the six-axis force sensors on the current market. We overcame the difficulties of weight loading device in high-precision calibration by proposing a self-calibration method based on the floating plate gravity and met the calibration precision requirement of 0.02% FS. This study has general implications for the development and calibration of high-precision multi-axis force sensors. In particular, the air-floating six-axis force measurement platform could be applied to the calibration of some special sensors such as flexible tactile sensors and may be used as a micro-nano mechanical assembly platform for real-time assembly force testing.

A torsion balance for impulse and thrust measurements of micro-Newton thrusters

NASA Astrophysics Data System (ADS)

Yang, Yuan-Xia; Tu, Liang-Cheng; Yang, Shan-Qing; Luo, Jun

2012-01-01

This paper reports the performance of a torsion-type thrust stand suitable for studies of micro-Newton thrusters, which is developed for ground testing the micro-Newton thruster in Chinese Test of the Equivalence Principle with Optical readout space mission. By virtue of specially suspending design and precise assembly of torsion balance configuration, the thrust stand with load capacity up to several kilograms is able to measure the impulse bit up to 1350 μNs with a resolution of 0.47 μNs, and the average thrust up to 264 μN with a resolution of 0.09 μN in both open and close loop operation. A pulsed plasma thruster, the preliminary prototype developed for Chinese TEPO space mission, is tested by the thrust stand, and the results reveal that the average impulse bit per pulse is measured to be 58.4 μNs with a repeatability of about 5%.

Printing Highly Controlled Suspended Carbon Nanotube Network on Micro-patterned Superhydrophobic Flexible Surface

PubMed Central

Li, Bo; Wang, Xin; Jung, Hyun Young; Kim, Young Lae; Robinson, Jeremy T.; Zalalutdinov, Maxim; Hong, Sanghyun; Hao, Ji; Ajayan, Pulickel M.; Wan, Kai-Tak; Jung, Yung Joon

2015-01-01

Suspended single-walled carbon nanotubes (SWCNTs) offer unique functionalities for electronic and electromechanical systems. Due to their outstanding flexible nature, suspended SWCNT architectures have great potential for integration into flexible electronic systems. However, current techniques for integrating SWCNT architectures with flexible substrates are largely absent, especially in a manner that is both scalable and well controlled. Here, we present a new nanostructured transfer paradigm to print scalable and well-defined suspended nano/microscale SWCNT networks on 3D patterned flexible substrates with micro- to nanoscale precision. The underlying printing/transfer mechanism, as well as the mechanical, electromechanical, and mechanical resonance properties of the suspended SWCNTs are characterized, including identifying metrics relevant for reliable and sensitive device structures. Our approach represents a fast, scalable and general method for building suspended nano/micro SWCNT architectures suitable for flexible sensing and actuation systems. PMID:26511284

Printing Highly Controlled Suspended Carbon Nanotube Network on Micro-patterned Superhydrophobic Flexible Surface.

PubMed

Li, Bo; Wang, Xin; Jung, Hyun Young; Kim, Young Lae; Robinson, Jeremy T; Zalalutdinov, Maxim; Hong, Sanghyun; Hao, Ji; Ajayan, Pulickel M; Wan, Kai-Tak; Jung, Yung Joon

2015-10-29

Suspended single-walled carbon nanotubes (SWCNTs) offer unique functionalities for electronic and electromechanical systems. Due to their outstanding flexible nature, suspended SWCNT architectures have great potential for integration into flexible electronic systems. However, current techniques for integrating SWCNT architectures with flexible substrates are largely absent, especially in a manner that is both scalable and well controlled. Here, we present a new nanostructured transfer paradigm to print scalable and well-defined suspended nano/microscale SWCNT networks on 3D patterned flexible substrates with micro- to nanoscale precision. The underlying printing/transfer mechanism, as well as the mechanical, electromechanical, and mechanical resonance properties of the suspended SWCNTs are characterized, including identifying metrics relevant for reliable and sensitive device structures. Our approach represents a fast, scalable and general method for building suspended nano/micro SWCNT architectures suitable for flexible sensing and actuation systems.

Micro-satellites thermal control—concepts and components

NASA Astrophysics Data System (ADS)

Baturkin, Volodymyr

2005-01-01

The main idea of this paper is to present the survey of current tendencies in micro-satellites thermal control concepts that can be rational and useful for posterior missions due to intensive expansion of satellites of such type. For this purpose, the available references and lessons learned by the National Technical University of Ukraine during the elaboration of thermal control hardware for micro-satellites Magion 4, 5, BIRD and autonomous thermal control systems for interplanetary missions VEGA, PHOBOS have been used. The main parameters taken into consideration for analysis are the satellite sizes, mass, power consumption, orbit parameters, altitude control peculiarities and thermal control description. It was defined that passive thermal control concepts are widely used, excepting autonomous temperature regulation for sensitive components such as batteries, high-precision optics, and some types of sensors. The practical means for realization of passive thermal control design as multi-layer insulation, optical coatings, heat conductive elements, gaskets are briefly described.

The Institutional Cost of Being a Professor of Color: Unveiling Micro-Aggression, Racial [In]visibility, and Racial Profiling through the Lens of Critical Race Theory

ERIC Educational Resources Information Center

Orelus, Pierre Wilbert

2013-01-01

Drawing on critical race theory, auto-ethnography, and resistant narratives, this article examines systemic forms of oppression that professors of color teaching at predominantly white institutions have been facing. The author incorporates in his analysis his experience as a faculty of color battling multiple forms of micro-aggression (Solorzano,…

Fibrous dosage forms by wet 3D-micro-patterning: process design, manufacture, and drug release rate.

PubMed

Blaesi, Aron H; Saka, Nannaji

2018-06-19

Recently, we have introduced fibrous dosage forms prepared by 3D-micro-patterning of drug-laden viscous melts. Such dosage forms enable predictable microstructures and increased drug release rates, and they can be manufactured continuously. However, melt processing is not applicable if the melting temperature of the formulation is greater than the degradation temperature of the drug or of the excipient. In this work, therefore, a continuous wet micro-patterning process that operates at ambient temperature is presented. The excipient is plasticized by a solvent and the patterned dosage form is solidified by air drying. Process models show that the micro-patterning time is the ratio of the fiber length in the dosage form and the velocity of the fiber stream. It was 1.3 minutes in the experiments, but can be reduced further. The drying time is limited by the diffusive flux of solvent through the fibers: it was about 3 minutes for the experimental conditions. Furthermore, models are developed to illustrate the effects of fiber radius, inter-fiber spacing, viscosity of the drug-excipient-solvent mixture, and drying conditions on the microstructure of the dosage form. Models and experimental results show that for a viscosity of the wet fibers of the order 10 3 Pa·s, both the patterned microstructure is well preserved and the crossed fibers are well bonded. Finally, the drug release rate by the dosage forms is experimentally determined and theoretically modeled. The results of the experiments validate the models fairly. Copyright © 2018. Published by Elsevier B.V.

UAV remote sening for precision agriculture

NASA Astrophysics Data System (ADS)

Vigneau, Nathalie; Chéron, Corentin; Mainfroy, Florent; Faroux, Romain

2014-05-01

Airinov offers to farmers, scientists and experimenters (plant breeders, etc.) its technical skills about UAVs, cartography and agronomic remote sensing. The UAV is a 2-m-wingspan flying wing. It can carry away either a RGB camera or a multispectral sensor, which records reflectance in 4 spectral bands. The spectral characteristics of the sensor are modular. Each spectral band is comprised between 400 and 850 nm and the FWHM (Full Width at Half Maximum) is between 10 and 40 nm. The spatial resolution varies according to sensor, flying height and user needs from 15cm/px for multispectral sensor at 150m to 1.5cm/px for RGB camera at 50m. The flight is totally automatic thanks to on-board autopilot, IMU (Inertial Measurement Unit) and GPS. Data processing (unvignetting, mosaicking, correction in reflectance) leads to agronomic variables as LAI (Leaf Area Index) or chlorophyll content for barley, wheat, rape and maize as well as vegetation indices as NDVI (Normalized Difference Vegetation Index). Using these data, Airinov can product advices for farmers as nitrogen preconisation for rape. For scientists, Airinov offers trial plot monitoring by micro-plots vectorisation and numerical data exctraction micro-plot by micro-plot. This can lead to kinetic curve for LAI or NDVI to compare cover establishment for different genotypes for example. Airinov's system is a new way to monitor plots with a lot of data (biophysical or biochemical parameters) at high rate, high spatial resolution and high precision.

Hybrid Systems: Cold Atoms Coupled to Micro Mechanical Oscillators =

NASA Astrophysics Data System (ADS)

Montoya Monge, Cris A.

Micro mechanical oscillators can serve as probes in precision measurements, as transducers to mediate photon-phonon interactions, and when functionalized with magnetic material, as tools to manipulate spins in quantum systems. This dissertation includes two projects where the interactions between cold atoms and mechanical oscillators are studied. In one of the experiments, we have manipulated the Zeeman state of magnetically trapped Rubidium atoms with a magnetic micro cantilever. The results show a spatially localized effect produced by the cantilever that agrees with Landau-Zener theory. In the future, such a scalable system with highly localized interactions and the potential for single-spin sensitivity could be useful for applications in quantum information science or quantum simulation. In a second experiment, work is in progress to couple a sample of optically trapped Rubidium atoms to a levitated nanosphere via an optical lattice. This coupling enables the cooling of the center-of-mass motion of the nanosphere by laser cooling the atoms. In this system, the atoms are trapped in the optical lattice while the sphere is levitated in a separate vacuum chamber by a single-beam optical tweezer. Theoretical analysis of such a system has determined that cooling the center-of-mass motion of the sphere to its quantum ground state is possible, even when starting at room temperature, due to the excellent environmental decoupling achievable in this setup. Nanospheres cooled to the quantum regime can provide new tests of quantum behavior at mesoscopic scales and have novel applications in precision sensing.

Analyzing the effect of tool edge radius on cutting temperature in micro-milling process

NASA Astrophysics Data System (ADS)

Liang, Y. C.; Yang, K.; Zheng, K. N.; Bai, Q. S.; Chen, W. Q.; Sun, G. Y.

2010-10-01

Cutting heat is one of the important physical subjects in the cutting process. Cutting heat together with cutting temperature produced by the cutting process will directly have effects on the tool wear and the life as well as on the workpiece processing precision and surface quality. The feature size of the workpiece is usually several microns. Thus, the tiny changes of cutting temperature will affect the workpiece on the surface quality and accuracy. Therefore, cutting heat and temperature generated in micro-milling will have significantly different effect than the one in the traditional tools cutting. In this paper, a two-dimensional coupled thermal-mechanical finite element model is adopted to determine thermal fields and cutting temperature during the Micro-milling process, by using software Deform-2D. The effect of tool edge radius on effective stress, effective strain, velocity field and cutting temperature distribution in micro-milling of aluminum alloy Al2024-T6 were investigated and analyzed. Also, the transient cutting temperature distribution was simulated dynamically. The simulation results show that the cutting temperature in Micro-milling is lower than those occurring in conventional milling processes due to the small loads and low cutting velocity. With increase of tool edge radius, the maximum temperature region gradually occurs on the contact region between finished surfaced and flank face of micro-cutter, instead of the rake face or the corner of micro-cutter. And this phenomenon shows an obvious size effect.

Some mechanisms for the formation of octopus-shaped iron micro-particles

NASA Astrophysics Data System (ADS)

Bica, Ioan

2004-08-01

Fluid spheres (micro-spheres or/and drops) are formed out of the metallic solid (the carbon steel semi-finished product) in the argon plasma of the transferred electric arc. For short intervals of time, the spheres are at rest with relation to vapors. The movement of the vapors around the spheres is in the same plane. It consists of a movement around a circle combined with the movement produced by a definitely located whirl. The molar concentration of the vapors is small in comparison with the molar density of the mixture formed of vapors and gas. At the intersection of the sphere and the plane of movement of the vapors, distinct stagnation point is formed. They constitute points of the beginning/and end of the current lines. Each current line is a carrier of a vapor cylinder. In time, the cylinder-gas interface reaches points of temperature equal to that of the "dew point" for iron. On this occasion a liquid membrane is formed. It delimits the vapor-gas mixture from the rest of the gas. Subsequent to the process of diffusion in non-stationary condition, the membrane becomes thicker and no vapors exist inside the tube. Needle-shaped micro-tubes are formed, in liquid phase, around the fluid sphere. By solidification, micro-particles occur, consisting of a central nucleus around which ligaments branch out.

Demineralized bone matrix fibers formable as general and custom 3D printed mold-based implants for promoting bone regeneration.

PubMed

Rodriguez, Rudy U; Kemper, Nathan; Breathwaite, Erick; Dutta, Sucharita M; Hsu, Erin L; Hsu, Wellington K; Francis, Michael P

2016-07-26

Bone repair frequently requires time-consuming implant construction, particularly when using un-formed implants with poor handling properties. We therefore developed osteoinductive, micro-fibrous surface patterned demineralized bone matrix (DBM) fibers for engineering both defect-matched and general three-dimensional implants. Implant molds were filled with demineralized human cortical bone fibers there were compressed and lyophilized, forming mechanically strong shaped DBM scaffolds. Enzyme linked immunosorbent assays and mass spectrometry confirmed that DBM fibers contained abundant osteogenic growth factors (bone morphogenetic proteins, insulin-like growth factor-I) and extracellular matrix proteins. Mercury porosimetry and mechanical testing showed interconnected pores within the mechanically stable, custom DBM fiber scaffolds. Mesenchymal stem cells readily attached to the DBM and showed increasing metabolic activity over time. DBM fibers further increased alkaline phosphatase activity in C2C12 cells. In vivo, DBM implants elicited osteoinductive potential in a mouse muscle pouch, and also promoted spine fusion in a rat arthrodesis model. DBM fibers can be engineered into custom-shaped, osteoinductive and osteoconductive implants with potential for repairing osseous defects with precise fitment, potentially reducing operating time. By providing pre-formed and custom implants, this regenerative allograft may improve patient outcomes following surgical bone repair, while further advancing personalized orthopedic and craniomaxillofacial medicine using three-dimensional-printed tissue molds.

Characterization of a microDiamond detector in high-dose-per-pulse electron beams for intra operative radiation therapy.

PubMed

Di Venanzio, C; Marinelli, Marco; Tonnetti, A; Verona-Rinati, G; Falco, M D; Pimpinella, M; Ciccotelli, A; De Stefano, S; Felici, G; Marangoni, F

2015-12-01

To characterize a synthetic diamond dosimeter (PTW Freiburg microDiamond 60019) in high dose-per-pulse electron beams produced by an Intra Operative Radiation Therapy (IORT) dedicated accelerator. The dosimetric properties of the microDiamond were assessed under 6, 8 and 9 MeV electron beams by a NOVAC11 mobile accelerator (Sordina IORT Technologies S.p.A.). The characterization was carried out with dose-per-pulse ranging from 26 to 105 mGy per pulse. The microDiamond performance was compared with an Advanced Markus ionization chamber and a PTW silicon diode E in terms of dose linearity, percentage depth dose (PDD) curves, beam profiles and output factors. A good linearity of the microDiamond response was verified in the dose range from 0.2 Gy to 28 Gy. A sensitivity of 1.29 nC/Gy was measured under IORT electron beams, resulting within 1% with respect to the one obtained in reference condition under (60)Co gamma irradiation. PDD measurements were found in agreement with the ones by the reference dosimeters, with differences in R50 values below 0.3 mm. Profile measurements evidenced a high spatial resolution of the microDiamond, slightly worse than the one of the silicon diode. The penumbra widths measured by the microDiamond resulted approximately 0.5 mm larger than the ones by the Silicon diode. Output factors measured by the microDiamond were found within 2% with those obtained by the Advanced Markus down to 3 cm diameter field sizes. The microDiamond dosimeter was demonstrated to be suitable for precise dosimetry in IORT applications under high dose-per-pulse conditions. Copyright © 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Creating micro-scale surface topology to achieve anisotropic wettability on an aluminum surface

NASA Astrophysics Data System (ADS)

Sommers, Andrew D.; Jacobi, Anthony M.

2006-08-01

A technique for fabricating micropatterned aluminum surfaces with parallel grooves 30 µm wide and tens of microns in depth is described. Standard photolithographic techniques are used to obtain this precise surface-feature patterning. Positive photoresists, S1813 and AZ4620, are selected to mask the surface, and a mixture of BCl3 and Cl2 gases is used to perform the etching. Experimental data show that a droplet placed on the micro-grooved aluminum surface using a micro-syringe exhibits an increased apparent contact angle, and for droplets condensed on these etched surfaces, more than a 50% reduction in the volume needed for the onset of droplet sliding is manifest. No chemical surface treatment is necessary to achieve this water repellency; it is accomplished solely by an anisotropic surface morphology that manipulates droplet geometry and creates and exploits discontinuities in the three-phase contact line. These micro-structured surfaces are proposed for use in a broad range of air-cooling applications, where the management of condensate and defrost liquid on the heat transfer surface is essential to the energy-efficient operation of the machine.

Micro-/nano-engineered cellular responses for soft tissue engineering and biomedical applications.

PubMed

Tay, Chor Yong; Irvine, Scott Alexander; Boey, Freddy Y C; Tan, Lay Poh; Venkatraman, Subbu

2011-05-23

The development of biomedical devices and reconstruction of functional ex vivo tissues often requires the need to fabricate biomimetic surfaces with features of sub-micrometer precision. This can be achieved with the advancements in micro-/nano-engineering techniques, allowing researchers to manipulate a plethora of cellular behaviors at the cell-biomaterial interface. Systematic studies conducted on these 2D engineered surfaces have unraveled numerous novel findings that can potentially be integrated as part of the design consideration for future 2D and 3D biomaterials and will no doubt greatly benefit tissue engineering. In this review, recent developments detailing the use of micro-/nano-engineering techniques to direct cellular orientation and function pertinent to soft tissue engineering will be highlighted. Particularly, this article aims to provide valuable insights into distinctive cell interactions and reactions to controlled surfaces, which can be exploited to understand the mechanisms of cell growth on micro-/nano-engineered interfaces, and to harness this knowledge to optimize the performance of 3D artificial soft tissue grafts and biomedical applications. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

MicroResearch--Finding sustainable solutions to local health challenges in East Africa.

PubMed

Kollmann, Tobias R; Bortolussi, Robert; MacDonald, Noni E

2015-06-01

The urgent need in Africa for research capacity building has been recognized by African leaders and governments for many years. However, lack of large research funding opportunities has been seen as a major obstacle to improving research capacity in precisely those countries that need it the most. Microfinance has shown that a small infusion of capital can "prime the pump" to creative local economic productivity. In a similar way, MicroResearch has proven effective in promoting a similar bottom-up strategy to find sustainable solutions to local health challenges through local community focused research. Specifically, MicroResearch through hands-on didactic courses, mentoring and small-scale research funding promotes small research projects that improve research skills across the entire health-care provider spectrum to unleash a culture of inquiry. This in turn stimulates health care providers to identify the locally most relevant obstacles that need to be overcome and implement locally feasible and sustainable solutions. MicroResearch is a bottom-up strategy proven effective at finding sustainable solutions to local health challenges. Copyright © 2015 The British Infection Association. Published by Elsevier Ltd. All rights reserved.

Dielectric barrier discharge micro-plasma emission spectrometry for the detection of acetone in exhaled breath.

PubMed

Yang, Ting; Gao, Dong-Xue; Yu, Yong-Liang; Chen, Ming-Li; Wang, Jian-Hua

2016-01-01

Acetone is a predominant volatile organic compound (VOC) in the exhaled breath and a promising biomarker for diabetes and ketoacidosis. A non-thermal micro-plasma generated in a planar dielectric barrier discharge (DBD) is used as a radiation source for the excitation of gaseous acetone followed by its quantification with optical emission spectrometry (OES). Gaseous acetone can be directly sampled, while liquid acetone is evaporated by heated tungsten coil and then introduced into the DBD micro-plasma by a helium carrier flow for performing optical emission and detection at a 519 nm emission line. In the present study, the exhaled breath is collected and transferred into aqueous medium for sampling. With a sampling volume of 7 μL in a micro-drop, a linear range of 40-1600 mg L(-1) is obtained along with a detection limit of 44 ng and a precision of 5.7% RSD. The present system is successfully applied to the determination of breath acetone for both diabetic patients and healthy volunteers. Copyright © 2015 Elsevier B.V. All rights reserved.

Characteristics for electrochemical machining with nanoscale voltage pulses.

PubMed

Lee, E S; Back, S Y; Lee, J T

2009-06-01

Electrochemical machining has traditionally been used in highly specialized fields, such as those of the aerospace and defense industries. It is now increasingly being applied in other industries, where parts with difficult-to-cut material, complex geometry and tribology, and devices of nanoscale and microscale are required. Electric characteristic plays a principal function role in and chemical characteristic plays an assistant function role in electrochemical machining. Therefore, essential parameters in electrochemical machining can be described current density, machining time, inter-electrode gap size, electrolyte, electrode shape etc. Electrochemical machining provides an economical and effective method for machining high strength, high tension and heat-resistant materials into complex shapes such as turbine blades of titanium and aluminum alloys. The application of nanoscale voltage pulses between a tool electrode and a workpiece in an electrochemical environment allows the three-dimensional machining of conducting materials with sub-micrometer precision. In this study, micro probe are developed by electrochemical etching and micro holes are manufactured using these micro probe as tool electrodes. Micro holes and microgroove can be accurately achieved by using nanoscale voltages pulses.

Critical issues for the application of integrated MEMS/CMOS technologies to inertial measurement units

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, J.H.; Ellis, J.R.; Montague, S.

1997-03-01

One of the principal applications of monolithically integrated micromechanical/microelectronic systems has been accelerometers for automotive applications. As integrated MEMS/CMOS technologies such as those developed by U.C. Berkeley, Analog Devices, and Sandia National Laboratories mature, additional systems for more sensitive inertial measurements will enter the commercial marketplace. In this paper, the authors will examine key technology design rules which impact the performance and cost of inertial measurement devices manufactured in integrated MEMS/CMOS technologies. These design parameters include: (1) minimum MEMS feature size, (2) minimum CMOS feature size, (3) maximum MEMS linear dimension, (4) number of mechanical MEMS layers, (5) MEMS/CMOS spacing.more » In particular, the embedded approach to integration developed at Sandia will be examined in the context of these technology features. Presently, this technology offers MEMS feature sizes as small as 1 {micro}m, CMOS critical dimensions of 1.25 {micro}m, MEMS linear dimensions of 1,000 {micro}m, a single mechanical level of polysilicon, and a 100 {micro}m space between MEMS and CMOS. This is applicable to modern precision guided munitions.« less

Dimensional metrology of smooth micro structures utilizing the spatial modulation of white-light interference fringes

NASA Astrophysics Data System (ADS)

Zhou, Yi; Tang, Yan; Deng, Qinyuan; Liu, Junbo; Wang, Jian; Zhao, Lixin

2017-08-01

Dimensional metrology for micro structure plays an important role in addressing quality issues and observing the performance of micro-fabricated products. In white light interferometry, the proposed method is expected to measure three-dimensional topography through modulation depth in spatial frequency domain. A normalized modulation depth is first obtained in the xy plane (image plane) for each CCD image individually. After that, the modulation depth of each pixel is analyzed along the scanning direction (z-axis) to reshape the topography of micro samples. Owing to the characteristics of modulation depth in broadband light interferometry, the method could effectively suppress the negative influences caused by light fluctuations and external irradiance disturbance. Both theory and experiments are elaborated in detail to verify that the modulation depth-based method can greatly level up the stability and sensitivity with satisfied precision in the measurement system. This technique can achieve an improved robustness in a complex measurement environment with the potential to be applied in online topography measurement such as chemistry and medical domains.

Frequency domain photothermoacoustic signal amplitude dependence on the optical properties of water: turbid polyvinyl chloride-plastisol system.

PubMed

Spirou, Gloria M; Mandelis, Andreas; Vitkin, I Alex; Whelan, William M

2008-05-10

Photoacoustic (more precisely, photothermoacoustic) signals generated by the absorption of photons can be related to the incident laser fluence rate. The dependence of frequency domain photoacoustic (FD-PA) signals on the optical absorption coefficient (micro(a)) and the effective attenuation coefficient (micro(eff)) of a turbid medium [polyvinyl chloride-plastisol (PVCP)] with tissuelike optical properties was measured, and empirical relationships between these optical properties and the photoacoustic (PA) signal amplitude and the laser fluence rate were derived for the water (PVCP system with and without optical scatterers). The measured relationships between these sample optical properties and the PA signal amplitude were found to be linear, consistent with FD-PA theory: micro(a)=a(A/Phi)-b and micro(eff)=c(A/Phi)+d, where Phi is the laser fluence, A is the FD-PA amplitude, and a, ...,d are empirical coefficients determined from the experiment using linear frequency-swept modulation and a lock-in heterodyne detection technique. This quantitative technique can easily be used to measure the optical properties of general turbid media using FD-PAs.

Biodegradable and Multifunctional Polymer Micro-Tubes for Targeting Photothermal Therapy

PubMed Central

Wang, Xin; Yu, Guoping; Han, Xiyu; Zhang, Hua; Ren, Jing; Wu, Xia; Qu, Yanfeng

2014-01-01

We describe an innovative form of polymer micro-tubes with diverse functions including biodegradation, magnetic manipulation, and photothermal effect that employs and activates photothermal therapy to target cancer cells. The micro-tube comprised soybean protein isolate, poly-l-glutamic acid, magnetite nanoparticles, plus gold nanoparticles. Through electrostatic force, these components, with opposite charges, formed pairs of layers in the pores of the template, various bilayers of soybean protein isolate and poly-l-glutamic acid served as the biodegradable building wall to each micro-tube. The layers of magnetite nanoparticle functionalized micro-tubes enabled the micro-tube manipulate to target the cancer cells by using an external magnetic field. The photo-thermal effect of the layer of gold nanoparticles on the outer surface of the micro-tubes, when under irradiation and when brought about by the near infrared radiation, elevated each sample’s temperature. In addition, and when under the exposure of the near infrared radiation, the elevated temperature of the suspension of the micro-tubes, likewise with a concentration of 0.2 mg/mL, and similarly with a power of 2 W and as well maintained for 10 min, elevated the temperature of the suspension beyond 42 °C. Such temperatures induced apoptosis of target cancer cells through the effect of photothermal therapy. The findings assert that structured micro-tubes have a promising application as a photothermal agent. From this assertion, the implications are that this multifunctional agent will significantly improve the methodology for cancer diagnosis and therapy. PMID:24992593

A Miniaturized On-Chip Colorimeter for Detecting NPK Elements

PubMed Central

Liu, Rui-Tao; Tao, Lu-Qi; Liu, Bo; Tian, Xiang-Guang; Mohammad, Mohammad Ali; Yang, Yi; Ren, Tian-Ling

2016-01-01

Recently, precision agriculture has become a globally attractive topic. As one of the most important factors, the soil nutrients play an important role in estimating the development of precision agriculture. Detecting the content of nitrogen, phosphorus and potassium (NPK) elements more efficiently is one of the key issues. In this paper, a novel chip-level colorimeter was fabricated to detect the NPK elements for the first time. A light source–microchannel photodetector in a sandwich structure was designed to realize on-chip detection. Compared with a commercial colorimeter, all key parts are based on MEMS (Micro-Electro-Mechanical System) technology so that the volume of this on-chip colorimeter can be minimized. Besides, less error and high precision are achieved. The cost of this colorimeter is two orders of magnitude less than that of a commercial one. All these advantages enable a low-cost and high-precision sensing operation in a monitoring network. The colorimeter developed herein has bright prospects for environmental and biological applications. PMID:27527177

A Miniaturized On-Chip Colorimeter for Detecting NPK Elements.

PubMed

Liu, Rui-Tao; Tao, Lu-Qi; Liu, Bo; Tian, Xiang-Guang; Mohammad, Mohammad Ali; Yang, Yi; Ren, Tian-Ling

2016-08-04

Recently, precision agriculture has become a globally attractive topic. As one of the most important factors, the soil nutrients play an important role in estimating the development of precision agriculture. Detecting the content of nitrogen, phosphorus and potassium (NPK) elements more efficiently is one of the key issues. In this paper, a novel chip-level colorimeter was fabricated to detect the NPK elements for the first time. A light source-microchannel photodetector in a sandwich structure was designed to realize on-chip detection. Compared with a commercial colorimeter, all key parts are based on MEMS (Micro-Electro-Mechanical System) technology so that the volume of this on-chip colorimeter can be minimized. Besides, less error and high precision are achieved. The cost of this colorimeter is two orders of magnitude less than that of a commercial one. All these advantages enable a low-cost and high-precision sensing operation in a monitoring network. The colorimeter developed herein has bright prospects for environmental and biological applications.

Spacecraft Alignment Determination and Control for Dual Spacecraft Precision Formation Flying

NASA Technical Reports Server (NTRS)

Calhoun, Philip C.; Novo-Gradac, Anne-Marie; Shah, Neerav

2017-01-01

Many proposed formation flying missions seek to advance the state of the art in spacecraft science imaging by utilizing precision dual spacecraft formation flying to enable a virtual space telescope. Using precision dual spacecraft alignment, very long focal lengths can be achieved by locating the optics on one spacecraft and the detector on the other. Proposed science missions include astrophysics concepts with spacecraft separations from 1000 km to 25,000 km, such as the Milli-Arc-Second Structure Imager (MASSIM) and the New Worlds Observer, and Heliophysics concepts for solar coronagraphs and X-ray imaging with smaller separations (50m 500m). All of these proposed missions require advances in guidance, navigation, and control (GNC) for precision formation flying. In particular, very precise astrometric alignment control and estimation is required for precise inertial pointing of the virtual space telescope to enable science imaging orders of magnitude better than can be achieved with conventional single spacecraft instruments. This work develops design architectures, algorithms, and performance analysis of proposed GNC systems for precision dual spacecraft astrometric alignment. These systems employ a variety of GNC sensors and actuators, including laser-based alignment and ranging systems, optical imaging sensors (e.g. guide star telescope), inertial measurement units (IMU), as well as micro-thruster and precision stabilized platforms. A comprehensive GNC performance analysis is given for Heliophysics dual spacecraft PFF imaging mission concept.

Health, Human Capital, and Development*

PubMed Central

Bleakley, Hoyt

2013-01-01

How much does disease depress development in human capital and income around the world? I discuss a range of micro evidence, which finds that health is both human capital itself and an input to producing other forms of human capital. I use a standard model to integrate these results, and suggest a re-interpretation of much of the micro literature. I then discuss the aggregate implications of micro estimates, but note the complications in extrapolating to general equilibrium, especially because of health’s effect on population size. I also review the macro evidence on this topic, which consists of either cross-country comparisons or measuring responses to health shocks. Micro estimates are 1–2 orders of magnitude smaller than the cross-country relationship, but nevertheless imply high benefit-to-cost ratios from improving certain forms of health. PMID:24147187

BEAMing LAMP: single-molecule capture and on-bead isothermal amplification for digital detection of hepatitis C virus in plasma.

PubMed

Chen, Jiyun; Xu, Xiaomin; Huang, Zhimei; Luo, Yuan; Tang, Lijuan; Jiang, Jian-Hui

2018-01-02

A novel dNAD platform (BEAMing LAMP) by combining emulsion micro-reactors, single-molecule magnetic capture and on-bead loop-mediated isothermal amplification has been developed for DNA detection, which enables absolute and high-precision quantification of a target with a detection limit of 300 copies.

Characteristics and formation mechanism for stainless steel fiber with periodic micro-fins

NASA Astrophysics Data System (ADS)

Tang, Tao; Wan, Zhenping; Lu, Longsheng; Tang, Yong

2016-05-01

Metal fibers have been widely used in many industrial applications due to their unique advantages. In certain applications, such as catalyst supports or orthopedic implants, a rough surface or tiny outshoots on the surface of metal fibers to increase surface area are needed. However, it has not been concerned about the surface morphologies of metal fiber in the current research of metal fiber manufacturing. In this paper, a special multi-tooth tool composed of a row of triangular tiny teeth is designed. The entire cutting layer of multi-tooth tool bifurcates into several thin cutting layers due to tiny teeth involved in cutting. As a result, several stainless steel fibers with periodic micro-fins are produced simultaneously. Morphology of periodic micro-fins is found to be diverse and can be classified into three categories: unilateral plane, unilateral tapering and bilateral. There are two forming mechanisms for the micro-fins. One is that periodic burrs remained on the free side of cutting layer of a tiny tooth create micro-fins of stainless steel fiber produced by the next neighboring tiny tooth; the other is that the connections between two fibers stuck together come to be micro-fins if the two fibers are finally detached. Influence of cutting conditions on formation of micro-fins is investigated. Experimental results show that cutting depth has no significant effect on micro-fin formation, high cutting speed is conducive to micro-fin formation, and feed should be between 0.12 mm/r and 0.2 mm/r to reliably obtain stainless steel fiber with micro-fins. This research presents a new pattern of stainless steel fiber characterized by periodic micro-fins formed on the edge of fiber and its manufacturing method.

Synchrotron Radiation Lithography for Manufacturing Integrated Circuits Beyond 100 nm.

PubMed

Kinoshita, H; Watanabe, T; Niibe, M

1998-05-01

Extreme ultraviolet lithography is a powerful tool for printing features of 0.1 micro m and below; in Japan and the USA there is a growing tendency to view it as the wave of the future. With Schwarzschild optics, replication of a 0.05 micro m pattern has been demonstrated in a 25 micro m square area. With a two-aspherical-mirror system, a 0.15 micro m pattern has been replicated in a ring slit area of 20 mm x 0.4 mm; a combination of this system with illumination optics and synchronized mask and wafer stages has enabled the replication of a 0.15 micro m pattern in an area of 10 mm x 12.5 mm. Furthermore, in the USA, the Sandia National Laboratory has succeeded in fabricating a fully operational NMOS transistor with a gate length of 0.1 micro m. The most challenging problem is the fabrication of mirrors with the required figure error of 0.28 nm. However, owing to advances in measurement technology, mirrors can now be made to a precision that almost satisfies this requirement. Therefore, it is time to move into a rapid development phase in order to obtain a system ready for practical use by the year 2004. In this paper the status of individual technologies is discussed in light of this situation, and future requirements for developing a practical system are considered.

The influence of the focus position on laser machining and laser micro-structuring monocrystalline diamond surface

NASA Astrophysics Data System (ADS)

Wu, Mingtao; Guo, Bing; Zhao, Qingliang; Fan, Rongwei; Dong, Zhiwei; Yu, Xin

2018-06-01

Micro-structured surface on diamond is widely used in microelectronics, optical elements, MEMS and NEMS components, ultra-precision machining tools, etc. The efficient micro-structuring of diamond material is still a challenging task. In this article, the influence of the focus position on laser machining and laser micro-structuring monocrystalline diamond surface were researched. At the beginning, the ablation threshold and its incubation effect of monocrystalline diamond were determined and discussed. As the accumulated laser pulses ranged from 40 to 5000, the laser ablation threshold decreased from 1.48 J/cm2 to 0.97 J/cm2. Subsequently, the variation of the ablation width and ablation depth in laser machining were studied. With enough pulse energy, the ablation width mainly depended on the laser propagation attributes while the ablation depth was a complex function of the focus position. Raman analysis was used to detect the variation of the laser machined diamond surface after the laser machining experiments. Graphite formation was discovered on the machined diamond surface and graphitization was enhanced after the defocusing quantity exceeded 45 μm. At last, several micro-structured surfaces were successfully fabricated on diamond surface with the defined micro-structure patterns and structuring ratios just by adjusting the defocusing quantity. The experimental structuring ratio was consistent with the theoretical analysis.

[Spirograph for small laboratory animals].

PubMed

Daniiarov, S B; Lanskiĭ, Iu M; Bebinov, E M

1986-10-01

A design of dry spirograph is described. It is characterized by greater precision, lack of inertia, high reliability, absence of respiration resistance, adequate form of recording, rapid resetting to any respiratory rate. The device consists of two similar injection syringes, photoelectric sensor for the identification of the initial moments of respiration stages, electromagnetic valves, two photoelectric converters of the air volume into the impulse signal, vacuum micro-pump, microcompressor and a system of air-driving tubes. In the initial position of pistons and valves the microcompressor pumps air into the inhalation cylinder and lifts the piston to the upper extreme position. With the signal marking the beginning of inspiration, the valves switch over and the piston lowers, pushing out the air, which moves into the animals' respiratory organs. Simultaneously, the signals of the inhaled air volume from the photoelectric transducer reach the recorder. During expiration the air pushes the piston down into the second cylinder and photoelectric transducer gives the information on the volume of the expired air.

Rice GH3 gene family: regulators of growth and development.

PubMed

Fu, Jing; Yu, Huihui; Li, Xianghua; Xiao, Jinghua; Wang, Shiping

2011-04-01

Auxin is an indispensable hormone throughout the lifetime of nearly all plant species. Several aspects of plant growth and development are rigidly governed by auxin, from micro to macro hierarchies; auxin also has a close relationship with plant-pathogen interactions. Undoubtedly, precise auxin levels are vitally important to plants, which have many effective mechanisms to maintain auxin homeostasis. One mechanism is conjugating amino acid to excessive indole-3-acetic acid (IAA; main form of auxin) through some GH3 family proteins to inactivate it. Our previous study demonstrated that GH3-2 mediated broad-spectrum resistance in rice (Oryza sativa L.) by suppressing pathogen-induced IAA accumulation and downregulating auxin signaling. Here, we further investigated the expression pattern of GH3-2 and other GH3 family paralogues in the life cycle of rice and presented the possible function of GH3-2 on rice root development by histochemical analysis of GH3-2 promoter:GUS reporter transgenic plants.

Wirelessly Controllable Inflated Electroactive Polymer (EAP) Reflectors

NASA Technical Reports Server (NTRS)

Bao, Xiaoqi; Bar-Cohen, Yoseph; Chang, Zensheu; Sherrit, Stewart; Badescu, Mircea

2005-01-01

Inflatable membrane reflectors are attractive for deployable, large aperture, lightweight optical and microwave systems in micro-gravity space environment. However, any fabrication flaw or temperature variation may results in significant aberration of the surface. Even for a perfectly fabricated inflatable membrane mirror with uniform thickness, theory shows it will form a Hencky curve surface but a desired parabolic or spherical surface. Precision control of the surfaceshape of extremely flexible membrane structures is a critical challenge for the success of this technology. Wirelessly controllable inflated reflectors made of electroactive polymers (EAP) are proposed in this paper. A finite element model was configured to predict the behavior of the inflatable EAP membranes under pre-strains, pressures and distributed electric charges on the surface. To explore the controllability of the inflatable EAP reflectors, an iteration algorism was developed to find the required electric actuation for correcting the aberration of the Hencky curve to the desired parabolic curve. The correction capability of the reflectors with available EAP materials was explored numerically and is presented in this paper.

Investigation of baseline measurement resolution of a Si plate-based extrinsic Fabry-Perot interferometer

NASA Astrophysics Data System (ADS)

Ushakov, Nikolai; Liokumovich, Leonid

2014-05-01

Measurement of a wafer thickness is of a great value for fabrication and interrogation of MEMS/MOEMS devices, as well as conventional optical fiber sensors. In the current paper we investigate the abilities of the wavelength-scanning interferometry techniques for registering the baseline of an extrinsic fiber Fabry-Perot interferometer (EFPI) with the cavity formed by the two sides of a silicon plate. In order to enhance the resolution, an improved signal processing algorithm was developed. Various experiments, including contact and non-contact measurement of a silicon wafer thickness were performed, with the achieved resolutions from 10 to 20 pm. This enables one to use the described approach for high-precision measurement of geometric parameters of micro electro (electro-optic) mechanical systems for their characterization, utilization in sensing tasks and fabrication control. An ability of a Si plate-based EFPI interrogated by the developed technique to capture temperature variations of about 4 mK was demonstrated.

Advances in Moire interferometry for thermal response of composites

NASA Technical Reports Server (NTRS)

Brooks, E. W., Jr.; Herakovich, C. T.; Post, D.; Hyer, M. W.

1982-01-01

An experimental technique for the precise measurement of the thermal response of both sides of a laminated composite coupon specimen uses Moire interferometry with fringe multiplication which yields a sensitivity of 833 nm (32.8 micro in.) per fringe. The reference gratings used are virtual gratings and are formed by partially mirrorized glass prisms in close proximity to the specimen. Results are compared with both results obtained from tests which used Moire interferometry on one side of composite laminates, and with those predicted by classical lamination theory. The technique is shown to be capable of producing the sensitivity and accuracy necessary to measure a wide range of thermal responses and to detect small side to side variations in the measured response. Tests were conducted on four laminate configurations of T300/5208 graphite epoxy over a temperature range of 297 K (75 F) to 422 K (300 F). The technique presented allows for the generation of reference gratings for temperature regimes well outside that used in these tests.

Development and test of photon counting lidar

NASA Astrophysics Data System (ADS)

Wang, Chun-hui; Wang, Ao-you; Tao, Yu-liang; Li, Xu; Peng, Huan; Meng, Pei-bei

2018-02-01

In order to satisfy the application requirements of spaceborne three dimensional imaging lidar , a prototype of nonscanning multi-channel lidar based on receiver field of view segmentation was designed and developed. High repetition frequency micro-pulse lasers, optics fiber array and Geiger-mode APD, combination with time-correlated single photon counting technology, were adopted to achieve multi-channel detection. Ranging experiments were carried out outdoors. In low echo photon condition, target photon counting showed time correlated and noise photon counting were random. Detection probability and range precision versus threshold were described and range precision increased from 0.44 to 0.11 when threshold increased from 4 to 8.

Precision Mechanical Measurement Using the Levitation Mass Method (LMM)

NASA Astrophysics Data System (ADS)

Fujii, Yusaku; Jin, Tao; Maru, Koichi

2010-12-01

The present status and the future prospects of a method for precision mass and force measurement, the levitation mass method (LMM), are reviewed. The LMM has been proposed and improved by the authors. In the LMM, the inertial force of a mass levitated using a pneumatic linear bearing is used as the reference force applied to the objects under test, such as force transducers, materials or structures. The inertial force of the levitated mass is measured using an optical interferometer. The three typical applications of the LMM, i.e. the dynamic force calibration, the micro force material tester and the space scale, are reviewed in this paper.

Using micro-seismicity and seismic velocities to map subsurface geologic and hydrologic structure within the Coso geothermal field, California

USGS Publications Warehouse

Kaven, Joern Ole; Hickman, Stephen H.; Davatzes, Nicholas C.

2012-01-01

Geothermal reservoirs derive their capacity for fluid and heat transport in large part from faults and fractures. Micro-seismicity generated on such faults and fractures can be used to map larger fault structures as well as secondary fractures that add access to hot rock, fluid storage and recharge capacity necessary to have a sustainable geothermal resource. Additionally, inversion of seismic velocities from micro-seismicity permits imaging of regions subject to the combined effects of fracture density, fluid pressure and steam content, among other factors. We relocate 14 years of seismicity (1996-2009) in the Coso geothermal field using differential travel times and simultaneously invert for seismic velocities to improve our knowledge of the subsurface geologic and hydrologic structure. We utilize over 60,000 micro-seismic events using waveform cross-correlation to augment to expansive catalog of P- and S-wave differential travel times recorded at Coso. We further carry out rigorous uncertainty estimation and find that our results are precise to within 10s of meters of relative location error. We find that relocated micro-seismicity outlines prominent, through-going faults in the reservoir in some cases. We also find that a significant portion of seismicity remains diffuse and does not cluster into more sharply defined major structures. The seismic velocity structure reveals heterogeneous distributions of compressional (Vp) and shear (Vs) wave speed, with Vp generally lower in the main field when compared to the east flank and Vs varying more significantly in the shallow portions of the reservoir. The Vp/Vs ratio appears to outline the two main compartments of the reservoir at depths of -0.5 to 1.5 km (relative to sea-level), with a ridge of relatively high Vp/Vs separating the main field from the east flank. In the deeper portion of the reservoir this ridge is less prominent. Our results indicate that high-precision relocations of micro-seismicity can provide useful insight into: 1) prominent structural features, faults and fractures that contribute to the flow of fluid and heat in the reservoir; 2) diffuse seismicity throughout the reservoir representing fractures that likely contribute to the overall permeability, storage and heat exchange capacity of the reservoir, but which are not confined to prominent faults; and 3) seismic velocities that outline the major hydrologic compartments within the Coso geothermal field.

Fabrication of a sensing module using micromachined biosensors.

PubMed

Suzuki, H; Arakawa, H; Karube, I

2001-12-01

Micromachining is a powerful tool in constructing micro biosensors and micro systems which incorporate them. A sensing module for blood components was fabricated using the technology. The analytes include glucose, urea, uric acid, creatine, and creatinine. Transducers used to construct the corresponding sensors were a Severinghaus-type carbon dioxide electrode for the urea sensor and a Clark-type oxygen electrode for the other analytes. In these electrodes, detecting electrode patterns were formed on a glass substrate by photolithography and the micro container for the internal electrolyte solution was formed on a silicon substrate by anisotropic etching. A through-hole was formed in the sensitive area, where a silicone gas-permeable membrane was formed and an enzyme was immobilized. The sensors were characterized in terms of pH and temperature dependence and calibration curves along with detection limits. Furthermore, the sensors were incorporated in an acrylate flow cell. Simultaneous operation of these sensors was successfully conducted and distinct and stable responses were observed for respective sensors.

Design of a small molecule against an oncogenic noncoding RNA

PubMed Central

Velagapudi, Sai Pradeep; Cameron, Michael D.; Haga, Christopher L.; Rosenberg, Laura H.; Lafitte, Marie; Duckett, Derek R.; Phinney, Donald G.; Disney, Matthew D.

2016-01-01

The design of precision, preclinical therapeutics from sequence is difficult, but advances in this area, particularly those focused on rational design, could quickly transform the sequence of disease-causing gene products into lead modalities. Herein, we describe the use of Inforna, a computational approach that enables the rational design of small molecules targeting RNA to quickly provide a potent modulator of oncogenic microRNA-96 (miR-96). We mined the secondary structure of primary microRNA-96 (pri-miR-96) hairpin precursor against a database of RNA motif–small molecule interactions, which identified modules that bound RNA motifs nearby and in the Drosha processing site. Precise linking of these modules together provided Targaprimir-96 (3), which selectively modulates miR-96 production in cancer cells and triggers apoptosis. Importantly, the compound is ineffective on healthy breast cells, and exogenous overexpression of pri-miR-96 reduced compound potency in breast cancer cells. Chemical Cross-Linking and Isolation by Pull-Down (Chem-CLIP), a small-molecule RNA target validation approach, shows that 3 directly engages pri-miR-96 in breast cancer cells. In vivo, 3 has a favorable pharmacokinetic profile and decreases tumor burden in a mouse model of triple-negative breast cancer. Thus, rational design can quickly produce precision, in vivo bioactive lead small molecules against hard-to-treat cancers by targeting oncogenic noncoding RNAs, advancing a disease-to-gene-to-drug paradigm. PMID:27170187

Novel process for production of micro lenses with increased centering accuracy and imaging performance

NASA Astrophysics Data System (ADS)

Wilde, C.; Langehanenberg, P.; Schenk, T.

2017-10-01

For modern production of micro lens systems, such as cementing of doublets or more lenses, precise centering of the lens edge is crucial. Blocking the lens temporarily on a centering arbor ensures that the centers of all optical lens surfaces coincide with the lens edge, while the arbor's axis serves as reference for both alignment and edging process. This theoretical assumption of the traditional cementing technology is not applicable for high-end production. In reality cement wedges between the bottom lens surface and the arbor's ring knife edge may occur and even expensive arbors with single-micron precision suffer from reduced quality of the ring knife edge after multiple usages and cleaning cycles. Consequently, at least the position of the bottom lens surface is undefined and the optical axis does not coincide with the arbor's reference axis! In order to overcome this basic problem in using centering arbors, we present a novel and efficient technique which can measure and align both surfaces of a lens with respect to the arbor axis with high accuracy and furthermore align additional lenses to the optical axis of the bottom lens. This is accomplished by aligning the lens without mechanical contact to the arbor. Thus the lens can be positioned in four degrees of freedom, while the centration errors of all lens surfaces are measured and considered. Additionally the arbor's reference axis is not assumed to be aligned to the rotation axis, but simultaneously measured with high precision.

[Micro fabricated enzyme battery].

PubMed

Sasaki, S; Karube, I

1996-10-01

Although various work has been done in the field of implantable micro actuators such as artificial organs and micro surgery robots, a suitable electric power supply for these is yet to be developed. For this purpose a micro fabricated enzyme fuel cell was developed which uses glucose contained in the human body as a fuel. In order to obtain enough voltage each cell was formed as part of a serial array on a silicon wafer. Glucose solution enters the cells by a capillary effect. In this article fuel cells already developed using biocatalysts are described, and the future possibility of a micro fabricated enzyme battery is discussed.

Multilayered membranes with tuned well arrays to be used as regenerative patches.

PubMed

Martins, Nádia I; Sousa, Maria P; Custódio, Catarina A; Pinto, Vânia C; Sousa, Paulo J; Minas, Graça; Cleymand, Franck; Mano, João F

2017-07-15

Membranes have been explored as patches in tissue repair and regeneration, most of them presenting a flat geometry or a patterned texture at the nano/micrometer scale. Herein, a new concept of a flexible membrane featuring well arrays forming pore-like environments to accommodate cell culture is proposed. The processing of such membranes using polysaccharides is based on the production of multilayers using the layer-by-layer methodology over a patterned PDMS substrate. The detached multilayered membrane exhibits a layer of open pores at one side and a total thickness of 38±2.2µm. The photolithography technology used to produce the molds allows obtaining wells on the final membranes with a tuned shape and micro-scale precision. The influence of post-processing procedures over chitosan/alginate films with 100 double layers, including crosslinking with genipin or fibronectin immobilization, on the adhesion and proliferation of human osteoblast-like cells is also investigated. The results suggest that the presence of patterned wells affects positively cell adhesion, morphology and proliferation. In particular, it is seen that cells colonized preferentially the well regions. The geometrical features with micro to sub-millimeter patterned wells, together with the nano-scale organization of the polymeric components along the thickness of the film will allow to engineer highly versatile multilayered membranes exhibiting a pore-like microstructure in just one of the sides, that could be adaptable in the regeneration of multiple tissues. Flexible multilayered membranes containing multiple micro-reservoirs are found as potential regenerative patches. Layer-by-layer (LbL) methodology over a featured PDMS substrate is used to produce patterned membranes, composed only by natural-based polymers, that can be easily detached from the PDMS substrate. The combination of nano-scale control of the polymeric organization along the thickness of the chitosan/alginate (CHT/ALG) membranes, provided by LbL, together with the geometrical micro-scale features of the patterned membranes offers a uniqueness system that allows cells to colonize 3-dimensionally. This study provides a promising strategy to control cellular spatial organization that can face the region of the tissue to regenerate. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Rotary Apparatus Concentrates And Separates Micro-Organisms

NASA Technical Reports Server (NTRS)

Noever, David A.

1992-01-01

Apparatus concentrates and separates swimming micro-organisms of different species into concentric rings in fluid. Fluid containing high concentration of desired species removed by use of small scoop placed into fluid at radius of one of rings formed by that species. Micro-organisms concentrated into concentric rings by combined dynamic effects of upward and horizontal components of swimming, rotation of dish, gravitation, and viscosity.

Three-dimensional microstructure simulation of Ni-based superalloy investment castings

NASA Astrophysics Data System (ADS)

Pan, Dong; Xu, Qingyan; Liu, Baicheng

2011-05-01

An integrated macro and micro multi-scale model for the three-dimensional microstructure simulation of Ni-based superalloy investment castings was developed, and applied to industrial castings to investigate grain evolution during solidification. A ray tracing method was used to deal with the complex heat radiation transfer. The microstructure evolution was simulated based on the Modified Cellular Automaton method, which was coupled with three-dimensional nested macro and micro grids. Experiments for Ni-based superalloy turbine wheel investment casting were carried out, which showed a good correspondence with the simulated results. It is indicated that the proposed model is able to predict the microstructure of the casting precisely, which provides a tool for the optimizing process.

Vibration Isolation Design for the Micro-X Rocket Payload

NASA Technical Reports Server (NTRS)

Heine, S. N. T.; Figueroa-Feliciano, E.; Rutherford, J. M.; Wikus, P.; Oakley, P.; Porter, Frederick S.; McCammon, D.

2014-01-01

Micro-X is a NASA-funded, sounding rocket-borne X-ray imaging spectrometer that will allow high precision measurements of velocity structure, ionization state and elemental composition of extended astrophysical systems. One of the biggest challenges in payload design is to maintain the temperature of the detectors during launch. There are several vibration damping stages to prevent energy transmission from the rocket skin to the detector stage, which causes heating during launch. Each stage should be more rigid than the outer stages to achieve vibrational isolation. We describe a major design effort to tune the resonance frequencies of these vibration isolation stages to reduce heating problems prior to the projected launch in the summer of 2014.

Micro-Scale Regenerative Heat Exchanger

NASA Technical Reports Server (NTRS)

Moran, Matthew E.; Stelter, Stephan; Stelter, Manfred

2004-01-01

A micro-scale regenerative heat exchanger has been designed, optimized and fabricated for use in a micro-Stirling device. Novel design and fabrication techniques enabled the minimization of axial heat conduction losses and pressure drop, while maximizing thermal regenerative performance. The fabricated prototype is comprised of ten separate assembled layers of alternating metal-dielectric composite. Each layer is offset to minimize conduction losses and maximize heat transfer by boundary layer disruption. A grating pattern of 100 micron square non-contiguous flow passages were formed with a nominal 20 micron wall thickness, and an overall assembled ten-layer thickness of 900 microns. Application of the micro heat exchanger is envisioned in the areas of micro-refrigerators/coolers, micropower devices, and micro-fluidic devices.

Photometric determination of phosphorus in mineralized biodiesel using a micro-flow-batch analyzer with solenoid micro-pumps.

PubMed

Lima, Marcelo B; Barreto, Inakã S; Andrade, Stéfani Iury E; Neta, Maria S S; Almeida, Luciano F; Araújo, Mário C U

2012-08-30

A method for the determination of phosphorus in mineralized biodiesel using a micro-flow-batch analyzer (μFBA) with solenoid micro-pumps was proposed. The samples were mineralized using an ashing procedure at 550 °C followed by dissolution of the residue. The determination of phosphorus was performed by employing the well-known molybdenum blue method. The measures of the absorbance were performed at 850 nm using an InfraRed LED integrated into the μFBA. Comparing with the reference method, no statistically significant differences were observed when applying the paired t-test at a 95% confidence level. Recovery study shows results between 97.9% and 105.8%. The proposed microsystem using solenoid micro-pumps presented satisfactory robustness and high sampling rate (190 h(-1)), with satisfactory reproducibility (relative standard deviation <4.5%, n=3), low reagents consumption (32 μL per analysis) and cost to build the device. Moreover, μFBA presents limit of detection (0.014 mg Kg(-1)), precision and accuracy compatible with the biodiesel regulations that establish a maximum concentration of 10 mg Kg(-1) (Brazil, USA, EU), suggesting that it is a good alternative for the determination of phosphorus in biodiesel. Copyright © 2012 Elsevier B.V. All rights reserved.

A Two-Dimensional Micro Scanner Integrated with a Piezoelectric Actuator and Piezoresistors

PubMed Central

Zhang, Chi; Zhang, Gaofei; You, Zheng

2009-01-01

A compact two-dimensional micro scanner with small volume, large deflection angles and high frequency is presented and the two-dimensional laser scanning is achieved by specular reflection. To achieve large deflection angles, the micro scanner excited by a piezoelectric actuator operates in the resonance mode. The scanning frequencies and the maximum scanning angles of the two degrees of freedom are analyzed by modeling and simulation of the structure. For the deflection angle measurement, piezoresistors are integrated in the micro scanner. The appropriate directions and crystal orientations of the piezoresistors are designed to obtain the large piezoresistive coefficients for the high sensitivities. Wheatstone bridges are used to measure the deflection angles of each direction independently and precisely. The scanner is fabricated and packaged with the piezoelectric actuator and the piezoresistors detection circuits in a size of 28 mm×20 mm×18 mm. The experiment shows that the two scanning frequencies are 216.8 Hz and 464.8 Hz, respectively. By an actuation displacement of 10 μm, the scanning range of the two-dimensional micro scanner is above 26° × 23°. The deflection angle measurement sensitivities for two directions are 59 mV/deg and 30 mV/deg, respectively. PMID:22389621

High-Sensitivity Encoder-Like Micro Area-Changed Capacitive Transducer for a Nano-g Micro Accelerometer

PubMed Central

Zheng, Panpan; Liu, Jinquan; Li, Zhu; Liu, Huafeng

2017-01-01

Encoder-like micro area-changed capacitive transducers are advantageous in terms of their better linearity and larger dynamic range compared to gap-changed capacitive transducers. Such transducers have been widely applied in rectilinear and rotational position sensors, lab-on-a-chip applications and bio-sensors. However, a complete model accounting for both the parasitic capacitance and fringe effect in area-changed capacitive transducers has not yet been developed. This paper presents a complete model for this type of transducer applied to a high-resolution micro accelerometer that was verified by both simulations and experiments. A novel optimization method involving the insertion of photosensitive polyimide was used to reduce the parasitic capacitance, and the capacitor spacing was decreased to overcome the fringe effect. The sensitivity of the optimized transducer was approximately 46 pF/mm, which was nearly 40 times higher than that of our previous transducer. The displacement detection resolution was measured as 50 pm/√Hz at 0.1 Hz using a precise capacitance detection circuit. Then, the transducer was applied to a sandwich in-plane micro accelerometer, and the measured level of the accelerometer was approximately 30 ng/√Hz at 1Hz. The earthquake that occurred in Taiwan was also detected during a continuous gravity measurement. PMID:28930176

Micro-patterned agarose gel devices for single-cell high-throughput microscopy of E. coli cells.

PubMed

Priest, David G; Tanaka, Nobuyuki; Tanaka, Yo; Taniguchi, Yuichi

2017-12-21

High-throughput microscopy of bacterial cells elucidated fundamental cellular processes including cellular heterogeneity and cell division homeostasis. Polydimethylsiloxane (PDMS)-based microfluidic devices provide advantages including precise positioning of cells and throughput, however device fabrication is time-consuming and requires specialised skills. Agarose pads are a popular alternative, however cells often clump together, which hinders single cell quantitation. Here, we imprint agarose pads with micro-patterned 'capsules', to trap individual cells and 'lines', to direct cellular growth outwards in a straight line. We implement this micro-patterning into multi-pad devices called CapsuleHotel and LineHotel for high-throughput imaging. CapsuleHotel provides ~65,000 capsule structures per mm 2 that isolate individual Escherichia coli cells. In contrast, LineHotel provides ~300 line structures per mm that direct growth of micro-colonies. With CapsuleHotel, a quantitative single cell dataset of ~10,000 cells across 24 samples can be acquired and analysed in under 1 hour. LineHotel allows tracking growth of > 10 micro-colonies across 24 samples simultaneously for up to 4 generations. These easy-to-use devices can be provided in kit format, and will accelerate discoveries in diverse fields ranging from microbiology to systems and synthetic biology.

A two-dimensional micro scanner integrated with a piezoelectric actuator and piezoresistors.

PubMed

Zhang, Chi; Zhang, Gaofei; You, Zheng

2009-01-01

A compact two-dimensional micro scanner with small volume, large deflection angles and high frequency is presented and the two-dimensional laser scanning is achieved by specular reflection. To achieve large deflection angles, the micro scanner excited by a piezoelectric actuator operates in the resonance mode. The scanning frequencies and the maximum scanning angles of the two degrees of freedom are analyzed by modeling and simulation of the structure. For the deflection angle measurement, piezoresistors are integrated in the micro scanner. The appropriate directions and crystal orientations of the piezoresistors are designed to obtain the large piezoresistive coefficients for the high sensitivities. Wheatstone bridges are used to measure the deflection angles of each direction independently and precisely. The scanner is fabricated and packaged with the piezoelectric actuator and the piezoresistors detection circuits in a size of 28 mm×20 mm×18 mm. The experiment shows that the two scanning frequencies are 216.8 Hz and 464.8 Hz, respectively. By an actuation displacement of 10 μm, the scanning range of the two-dimensional micro scanner is above 26° × 23°. The deflection angle measurement sensitivities for two directions are 59 mV/deg and 30 mV/deg, respectively.

A design multifunctional plasmonic optical device by micro ring system

NASA Astrophysics Data System (ADS)

Pornsuwancharoen, N.; Youplao, P.; Amiri, I. S.; Ali, J.; Yupapin, P.

2018-03-01

A multi-function electronic device based on the plasmonic circuit is designed and simulated by using the micro-ring system. From which a nonlinear micro-ring resonator is employed and the selected electronic devices such as rectifier, amplifier, regulator and filter are investigated. A system consists of a nonlinear micro-ring resonator, which is known as a modified add-drop filter and made of an InGaAsP/InP material. The stacked waveguide of an InGaAsP/InP - graphene -gold/silver is formed as a part of the device, the required output signals are formed by the specific control of input signals via the input and add ports. The material and device aspects are reviewed. The simulation results are obtained using the Opti-wave and MATLAB software programs, all device parameters are based on the fabrication technology capability.

Experimental study and numerical simulation on the structural and mechanical properties of Typha leaves through multimodal microscopy approaches.

PubMed

Liu, Jingjing; Zhang, Zhihui; Yu, Zhenglei; Liang, Yunhong; Li, Xiujuan; Ren, Luquan

2018-01-01

The Typha leaf, with special multi-level structure, low density and excellent mechanical properties, is an ideal bionic prototype utilized for lightweight design. In order to further study the relationship between the structure and mechanical properties, the three-dimensional macroscopic morphology of Typha leaves was characterized by micro computed tomography (Micro-CT) and its internal microstructure was observed by scanning electron microscopy (SEM). The combination of experimental and computational research was carried out in this paper, to reveal and verify the effect of multi-level structure on the mechanical properties. A universal testing machine and a self-developed mechanical testing apparatus with high precision and low load were used to measure the mechanical properties of the axial compression and lateral bending of the leaves, respectively. Three models with different internal structures were established based on the above-mentioned three-dimensional morphologies. The result demonstrated that the structure of partitions and diaphragms within the Typha leaf could form a reinforcement ribs structure which could provide multiple load paths and make the process of compression and bending difficult. The further nonlinear finite element analysis through LS-DYNA proved that internal structure could improve the ability of the models to resist compression and deformation. The investigation can be the reference for lightweight thin-walled structure design and inspire the application of the bionic structural materials. Copyright © 2017 Elsevier Ltd. All rights reserved.

Integrated Multilayer Insulation

NASA Technical Reports Server (NTRS)

Dye, Scott

2009-01-01

Integrated multilayer insulation (IMLI) is being developed as an improved alternative to conventional multilayer insulation (MLI), which is more than 50 years old. A typical conventional MLI blanket comprises between 10 and 120 metallized polymer films separated by polyester nets. MLI is the best thermal- insulation material for use in a vacuum, and is the insulation material of choice for spacecraft and cryogenic systems. However, conventional MLI has several disadvantages: It is difficult or impossible to maintain the desired value of gap distance between the film layers (and consequently, it is difficult or impossible to ensure consistent performance), and fabrication and installation are labor-intensive and difficult. The development of IMLI is intended to overcome these disadvantages to some extent and to offer some additional advantages over conventional MLI. The main difference between IMLI and conventional MLI lies in the method of maintaining the gaps between the film layers. In IMLI, the film layers are separated by what its developers call a micro-molded discrete matrix, which can be loosely characterized as consisting of arrays of highly engineered, small, lightweight, polymer (typically, thermoplastic) frames attached to, and placed between, the film layers. The term "micro-molded" refers to both the smallness of the frames and the fact that they are fabricated in a process that forms precise small features, described below, that are essential to attainment of the desired properties. The term "discrete" refers to the nature of the matrix as consisting of separate frames, in contradistinction to a unitary frame spanning entire volume of an insulation blanket.

Three-dimensional representation of the human cochlea using micro-computed tomography data: presenting an anatomical model for further numerical calculations.

PubMed

Braun, Katharina; Böhnke, Frank; Stark, Thomas

2012-06-01

We present a complete geometric model of the human cochlea, including the segmentation and reconstruction of the fluid-filled chambers scala tympani and scala vestibuli, the lamina spiralis ossea and the vibrating structure (cochlear partition). Future fluid-structure coupled simulations require a reliable geometric model of the cochlea. The aim of this study was to present an anatomical model of the human cochlea, which can be used for further numerical calculations. Using high resolution micro-computed tomography (µCT), we obtained images of a cut human temporal bone with a spatial resolution of 5.9 µm. Images were manually segmented to obtain the three-dimensional reconstruction of the cochlea. Due to the high resolution of the µCT data, a detailed examination of the geometry of the twisted cochlear partition near the oval and the round window as well as the precise illustration of the helicotrema was possible. After reconstruction of the lamina spiralis ossea, the cochlear partition and the curved geometry of the scala vestibuli and the scala tympani were presented. The obtained data sets were exported as standard lithography (stl) files. These files represented a complete framework for future numerical simulations of mechanical (acoustic) wave propagation on the cochlear partition in the form of mathematical mechanical cochlea models. Additional quantitative information concerning heights, lengths and volumes of the scalae was found and compared with previous results.

Micro-finite-element method to assess elastic properties of trabecular bone at micro- and macroscopic level.

PubMed

Rieger, R; Auregan, J C; Hoc, T

2018-03-01

The objective of the present study is to assess the mechanical behavior of trabecular bone based on microCT imaging and micro-finite-element analysis. In this way two methods are detailed: (i) direct determination of macroscopic elastic property of trabecular bone; (ii) inverse approach to assess mechanical properties of trabecular bone tissue. Thirty-five females and seven males (forty-two subjects) mean aged (±SD) 80±11.7 years from hospitals of Assistance publique-Hôpitaux de Paris (AP-HP) diagnosed with osteoporosis following a femoral neck fracture due to a fall from standing were included in this study. Fractured heads were collected during hip replacement surgery. Standardized bone cores were removed from the femoral head's equator by a trephine in a water bath. MicroCT images acquisition and analysis were performed with CTan ® software and bone volume fraction was then determined. Micro-finite-element simulations were per-formed using Abaqus 6.9-2 ® software in order to determine the macroscopic mechanical behaviour of the trabecular bone. After microCT acquisition, a longitudinal compression test was performed and the experimental macroscopic Young's Modulus was extracted. An inverse approach based on the whole trabecular bone's mechanical response and micro-finite-element analysis was performed to determine microscopic mechanical properties of trabecular bone. In the present study, elasticity of the tissue was shown to be similar to that of healthy tissue but with a lower yield stress. Classical histomorphometric analysis form microCT imaging associated with an inverse micro-finite-element method allowed to assess microscopic mechanical trabecular bone parameters. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Histological examination of the oral mucosa after fractional diode laser irradiation with different power and pulse duration

NASA Astrophysics Data System (ADS)

Belikov, Andrey V.; Ermolaeva, Ludmila A.; Korzhevsky, Dmitriy E.; Sergeeva, Elena S.; Semyashkina, Yulia V.; Antropova, Maria M.; Fedotov, Denis Y.; Zaitseva, Maria A.; Kashina, Tatiana V.

2018-04-01

Optical and histological methods were used to examination of influence the power and pulse duration of 980-nm diode laser to the dimensions and morphology of tissue around fractional micro injuries created by the radiation of that laser in the oral mucosa of rats in vivo. The power of laser radiation (P) varied in the range of 1÷21 W, and its pulse duration (tp) - in the range 50÷500 ms. Histological examination showed that in the mucosa of the oral cavity after the laser fractional irradiation, there following effects are found: a tissue defect, a transudate in the lumen of ablative micro injury, stretching and compacting effect of the nuclei of the basal epithelium, the disappearance of granules of the keratohialin, destroying the structure of the connective tissue, erythrocyte stasis in the vessels, the disappearance of transverse striation in the muscle fibers in muscle layer. It has been found that ablative micro injury begins to form up at P = 5 W, tp = 100 ms and affects only the epithelial layer of the mucosa. At P = 7 W, tp = 120 ms, the ratio of width to depth of ablative micro injury is 1 : 1, and at P = 10 W, tp = 100 ms, an ablative micro column with ratio of 1 : 1.5 is formed in the epithelial and submucosal layers of the mucosa. The laser effect with P = 15 W, tp = 200 ms leads to lengthening of the ablation micro-column to 1 : 2, with the bottom of the ablative micro column reaching the muscular layer. With a further growth of laser power or pulse duration, the width of the micro injury increases, and the growth of the micro injury depth is slowed down so that the micro column buildup is ceased.

Forming Mandrels for X-Ray Mirror Substrates

NASA Technical Reports Server (NTRS)

Blake, Peter N.; Saha. To,p; Zhang, Will; O'Dell, Stephen; Kester, Thomas; Jones, William

2011-01-01

Precision forming mandrels are one element in X-ray mirror development at NASA. Current mandrel fabrication process is capable of meeting the allocated precision requirements for a 5 arcsec telescope. A manufacturing plan is outlined for a large IXO-scale program.

Precision forging technology for aluminum alloy

NASA Astrophysics Data System (ADS)

Deng, Lei; Wang, Xinyun; Jin, Junsong; Xia, Juchen

2018-03-01

Aluminum alloy is a preferred metal material for lightweight part manufacturing in aerospace, automobile, and weapon industries due to its good physical properties, such as low density, high specific strength, and good corrosion resistance. However, during forging processes, underfilling, folding, broken streamline, crack, coarse grain, and other macro- or microdefects are easily generated because of the deformation characteristics of aluminum alloys, including narrow forgeable temperature region, fast heat dissipation to dies, strong adhesion, high strain rate sensitivity, and large flow resistance. Thus, it is seriously restricted for the forged part to obtain precision shape and enhanced property. In this paper, progresses in precision forging technologies of aluminum alloy parts were reviewed. Several advanced precision forging technologies have been developed, including closed die forging, isothermal die forging, local loading forging, metal flow forging with relief cavity, auxiliary force or vibration loading, casting-forging hybrid forming, and stamping-forging hybrid forming. High-precision aluminum alloy parts can be realized by controlling the forging processes and parameters or combining precision forging technologies with other forming technologies. The development of these technologies is beneficial to promote the application of aluminum alloys in manufacturing of lightweight parts.

Micro-Environmental Signature of The Interactions between Druggable Target Protein, Dipeptidyl Peptidase-IV, and Anti-Diabetic Drugs.

PubMed

Chakraborty, Chiranjib; Mallick, Bidyut; Sharma, Ashish Ranjan; Sharma, Garima; Jagga, Supriya; Doss, C George Priya; Nam, Ju-Suk; Lee, Sang-Soo

2017-01-01

Druggability of a target protein depends on the interacting micro-environment between the target protein and drugs. Therefore, a precise knowledge of the interacting micro-environment between the target protein and drugs is requisite for drug discovery process. To understand such micro-environment, we performed in silico interaction analysis between a human target protein, Dipeptidyl Peptidase-IV (DPP-4), and three anti-diabetic drugs (saxagliptin, linagliptin and vildagliptin). During the theoretical and bioinformatics analysis of micro-environmental properties, we performed drug-likeness study, protein active site predictions, docking analysis and residual interactions with the protein-drug interface. Micro-environmental landscape properties were evaluated through various parameters such as binding energy, intermolecular energy, electrostatic energy, van der Waals'+H-bond+desolvo energy (E VHD ) and ligand efficiency (LE) using different in silico methods. For this study, we have used several servers and software, such as Molsoft prediction server, CASTp server, AutoDock software and LIGPLOT server. Through micro-environmental study, highest log P value was observed for linagliptin (1.07). Lowest binding energy was also observed for linagliptin with DPP-4 in the binding plot. We also identified the number of H-bonds and residues involved in the hydrophobic interactions between the DPP-4 and the anti-diabetic drugs. During interaction, two H-bonds and nine residues, two H-bonds and eleven residues as well as four H-bonds and nine residues were found between the saxagliptin, linagliptin as well as vildagliptin cases and DPP-4, respectively. Our in silico data obtained for drug-target interactions and micro-environmental signature demonstrates linagliptin as the most stable interacting drug among the tested anti-diabetic medicines.

Soil CO2 flux in response to elevated atmospheric CO2 and nitrogen fertilization: patterns and methods

Treesearch

James M. Vose; Katherine J. Elliott; D.W. Johnson

1995-01-01

The evolution of carbon dioxide (CO2) from soils is due to the metabolic activity of roots, mycorrhizae, and soil micro- and macro-organisms. Although precise estimates of carbon (C) recycled to the atmosphere from belowground sources are unavailable, Musselman and Fox (1991) propose that the belowground contribution exceeds 100 Pg y-1...

Automatic arrival time detection for earthquakes based on Modified Laplacian of Gaussian filter

NASA Astrophysics Data System (ADS)

Saad, Omar M.; Shalaby, Ahmed; Samy, Lotfy; Sayed, Mohammed S.

2018-04-01

Precise identification of onset time for an earthquake is imperative in the right figuring of earthquake's location and different parameters that are utilized for building seismic catalogues. P-wave arrival detection of weak events or micro-earthquakes cannot be precisely determined due to background noise. In this paper, we propose a novel approach based on Modified Laplacian of Gaussian (MLoG) filter to detect the onset time even in the presence of very weak signal-to-noise ratios (SNRs). The proposed algorithm utilizes a denoising-filter algorithm to smooth the background noise. In the proposed algorithm, we employ the MLoG mask to filter the seismic data. Afterward, we apply a Dual-threshold comparator to detect the onset time of the event. The results show that the proposed algorithm can detect the onset time for micro-earthquakes accurately, with SNR of -12 dB. The proposed algorithm achieves an onset time picking accuracy of 93% with a standard deviation error of 0.10 s for 407 field seismic waveforms. Also, we compare the results with short and long time average algorithm (STA/LTA) and the Akaike Information Criterion (AIC), and the proposed algorithm outperforms them.

An adaptive compensation algorithm for temperature drift of micro-electro-mechanical systems gyroscopes using a strong tracking Kalman filter.

PubMed

Feng, Yibo; Li, Xisheng; Zhang, Xiaojuan

2015-05-13

We present an adaptive algorithm for a system integrated with micro-electro-mechanical systems (MEMS) gyroscopes and a compass to eliminate the influence from the environment, compensate the temperature drift precisely, and improve the accuracy of the MEMS gyroscope. We use a simplified drift model and changing but appropriate model parameters to implement this algorithm. The model of MEMS gyroscope temperature drift is constructed mostly on the basis of the temperature sensitivity of the gyroscope. As the state variables of a strong tracking Kalman filter (STKF), the parameters of the temperature drift model can be calculated to adapt to the environment under the support of the compass. These parameters change intelligently with the environment to maintain the precision of the MEMS gyroscope in the changing temperature. The heading error is less than 0.6° in the static temperature experiment, and also is kept in the range from 5° to -2° in the dynamic outdoor experiment. This demonstrates that the proposed algorithm exhibits strong adaptability to a changing temperature, and performs significantly better than KF and MLR to compensate the temperature drift of a gyroscope and eliminate the influence of temperature variation.

Electrohydrodynamic inkjet printing of Pd loaded SnO2 nanofibers on a CMOS micro hotplate for low power H2 detection

NASA Astrophysics Data System (ADS)

Wu, Hao; Yu, Jun; Cao, Rui; Yang, Yinghua; Tang, Zhenan

2018-05-01

A high-performance low-power micro hotplate (MHP) hydrogen sensor was fabricated through electrohydrodynamic (EHD) inkjet printing technique. Electrospun Pd loaded SnO2 nanofibers with lengths of 250-850 nm were precisely printed on the suspended central part of an MHP with an area of 100 um × 100 um. The printhead in the printing system was a low-cost metallic needle with an inner diameter of 110 um, which was large enough to prevent clogging by the nanofibers. The printing process was observed by a high-speed camera. Small droplets with diameters of 50-80 um were produced at each ejection by providing a high voltage to the metallic needle. It was found that the bridge-type MHPs used in our experiment can promote the positioning precision due to its bound effect to the droplet. In the gas sensing measurement, the Pd loaded SnO2 MHP gas sensor showed a remarkable response to H2 with a low power of only 9.1 mW. The experiment results demonstrate the excellent adequacy of EHD inkjet printing technique to realize effective mass fabrication of MHP gas sensors or sensor arrays.

Analytical Kinematics and Coupled Vibrations Analysis of Mechanical System Operated by Solar Array Drive Assembly

NASA Astrophysics Data System (ADS)

Sattar, M.; Wei, C.; Jalali, A.; Sattar, R.

2017-07-01

To address the impact of solar array (SA) anomalies and vibrations on performance of precision space-based operations, it is important to complete its accurate jitter analysis. This work provides mathematical modelling scheme to approximate kinematics and coupled micro disturbance dynamics of rigid load supported and operated by solar array drive assembly (SADA). SADA employed in analysis provides a step wave excitation torque to activate the system. Analytical investigations into kinematics is accomplished by using generalized linear and Euler angle coordinates, applying multi-body dynamics concepts and transformations principles. Theoretical model is extended, to develop equations of motion (EoM), through energy method (Lagrange equation). The main emphasis is to research coupled frequency response by determining energies dissipated and observing dynamic behaviour of internal vibratory systems of SADA. The disturbance model captures discrete active harmonics of SADA, natural modes and vibration amplifications caused by interactions between active harmonics and structural modes of mechanical assembly. The proposed methodology can help to predict true micro disturbance nature of SADA operating rigid load. Moreover, performance outputs may be compared against actual mission requirements to assess precise spacecraft controller design to meet next space generation stringent accuracy goals.

Development of novel hybrid flexure-based microgrippers for precision micro-object manipulation.

PubMed

Mohd Zubir, Mohd Nashrul; Shirinzadeh, Bijan; Tian, Yanling

2009-06-01

This paper describes the process of developing a microgripper that is capable of high precision and fidelity manipulation of micro-objects. The design adopts the concept of flexure-based hinges on its joints to provide the rotational motion, thus eliminating the inherent nonlinearities associated with the application of conventional rigid hinges. A combination of two modeling techniques, namely, pseudorigid body model and finite element analysis was utilized to expedite the prototyping procedure, which leads to the establishment of a high performance mechanism. A new hybrid compliant structure integrating cantilever beam and flexural hinge configurations within microgripper mechanism mainframe has been developed. This concept provides a novel approach to harness the advantages within each individual configuration while mutually compensating the limitations inherent between them. A wire electrodischarge machining technique was utilized to fabricate the gripper out of high grade aluminum alloy (Al 7075T6). Experimental studies were conducted on the model to obtain various correlations governing the gripper performance as well as for model verification. The experimental results demonstrate high level of compliance in comparison to the computational results. A high amplification characteristic and maximum achievable stroke of 100 microm can be achieved.

Current knowledge of microRNA-mediated regulation of drug metabolism in humans.

PubMed

Nakano, Masataka; Nakajima, Miki

2018-05-01

Understanding the factors causing inter- and intra-individual differences in drug metabolism potencies is required for the practice of personalized or precision medicine, as well as for the promotion of efficient drug development. The expression of drug-metabolizing enzymes is controlled by transcriptional regulation by nuclear receptors and transcriptional factors, epigenetic regulation, such as DNA methylation and histone acetylation, and post-translational modification. In addition to such regulation mechanisms, recent studies revealed that microRNAs (miRNAs), endogenous ~22-nucleotide non-coding RNAs that regulate gene expression through the translational repression and degradation of mRNAs, significantly contribute to post-transcriptional regulation of drug-metabolizing enzymes. Areas covered: This review summarizes the current knowledge regarding miRNAs-dependent regulation of drug-metabolizing enzymes and transcriptional factors and its physiological and clinical significance. We also describe recent advances in miRNA-dependent regulation research, showing that the presence of pseudogenes, single-nucleotide polymorphisms, and RNA editing affects miRNA targeting. Expert opinion: It is unwavering fact that miRNAs are critical factors causing inter- and intra-individual differences in the expression of drug-metabolizing enzymes. Consideration of miRNA-dependent regulation would be a helpful tool for optimizing personalized and precision medicine.

Development of novel hybrid flexure-based microgrippers for precision micro-object manipulation

NASA Astrophysics Data System (ADS)

Mohd Zubir, Mohd Nashrul; Shirinzadeh, Bijan; Tian, Yanling

2009-06-01

This paper describes the process of developing a microgripper that is capable of high precision and fidelity manipulation of micro-objects. The design adopts the concept of flexure-based hinges on its joints to provide the rotational motion, thus eliminating the inherent nonlinearities associated with the application of conventional rigid hinges. A combination of two modeling techniques, namely, pseudorigid body model and finite element analysis was utilized to expedite the prototyping procedure, which leads to the establishment of a high performance mechanism. A new hybrid compliant structure integrating cantilever beam and flexural hinge configurations within microgripper mechanism mainframe has been developed. This concept provides a novel approach to harness the advantages within each individual configuration while mutually compensating the limitations inherent between them. A wire electrodischarge machining technique was utilized to fabricate the gripper out of high grade aluminum alloy (Al 7075T6). Experimental studies were conducted on the model to obtain various correlations governing the gripper performance as well as for model verification. The experimental results demonstrate high level of compliance in comparison to the computational results. A high amplification characteristic and maximum achievable stroke of 100 μm can be achieved.

Biomarker microRNAs for prostate cancer metastasis: screened with a network vulnerability analysis model.

PubMed

Lin, Yuxin; Chen, Feifei; Shen, Li; Tang, Xiaoyu; Du, Cui; Sun, Zhandong; Ding, Huijie; Chen, Jiajia; Shen, Bairong

2018-05-21

Prostate cancer (PCa) is a fatal malignant tumor among males in the world and the metastasis is a leading cause for PCa death. Biomarkers are therefore urgently needed to detect PCa metastatic signature at the early time. MicroRNAs are small non-coding RNAs with the potential to be biomarkers for disease prediction. In addition, computer-aided biomarker discovery is now becoming an attractive paradigm for precision diagnosis and prognosis of complex diseases. In this study, we identified key microRNAs as biomarkers for predicting PCa metastasis based on network vulnerability analysis. We first extracted microRNAs and mRNAs that were differentially expressed between primary PCa and metastatic PCa (MPCa) samples. Then we constructed the MPCa-specific microRNA-mRNA network and screened microRNA biomarkers by a novel bioinformatics model. The model emphasized the characterization of systems stability changes and the network vulnerability with three measurements, i.e. the structurally single-line regulation, the functional importance of microRNA targets and the percentage of transcription factor genes in microRNA unique targets. With this model, we identified five microRNAs as putative biomarkers for PCa metastasis. Among them, miR-101-3p and miR-145-5p have been previously reported as biomarkers for PCa metastasis and the remaining three, i.e. miR-204-5p, miR-198 and miR-152, were screened as novel biomarkers for PCa metastasis. The results were further confirmed by the assessment of their predictive power and biological function analysis. Five microRNAs were identified as candidate biomarkers for predicting PCa metastasis based on our network vulnerability analysis model. The prediction performance, literature exploration and functional enrichment analysis convinced our findings. This novel bioinformatics model could be applied to biomarker discovery for other complex diseases.

Nanomaterials for Cancer Precision Medicine.

PubMed

Wang, Yilong; Sun, Shuyang; Zhang, Zhiyuan; Shi, Donglu

2018-04-01

Medical science has recently advanced to the point where diagnosis and therapeutics can be carried out with high precision, even at the molecular level. A new field of "precision medicine" has consequently emerged with specific clinical implications and challenges that can be well-addressed by newly developed nanomaterials. Here, a nanoscience approach to precision medicine is provided, with a focus on cancer therapy, based on a new concept of "molecularly-defined cancers." "Next-generation sequencing" is introduced to identify the oncogene that is responsible for a class of cancers. This new approach is fundamentally different from all conventional cancer therapies that rely on diagnosis of the anatomic origins where the tumors are found. To treat cancers at molecular level, a recently developed "microRNA replacement therapy" is applied, utilizing nanocarriers, in order to regulate the driver oncogene, which is the core of cancer precision therapeutics. Furthermore, the outcome of the nanomediated oncogenic regulation has to be accurately assessed by the genetically characterized, patient-derived xenograft models. Cancer therapy in this fashion is a quintessential example of precision medicine, presenting many challenges to the materials communities with new issues in structural design, surface functionalization, gene/drug storage and delivery, cell targeting, and medical imaging. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Functional Differences Between Placental Micro- and Macrovascular Endothelial Colony-Forming Cells

PubMed Central

Solomon, Ioana; O’Reilly, Megan; Ionescu, Lavinia; Alphonse, Rajesh S.; Rajabali, Saima; Zhong, Shumei; Vadivel, Arul; Shelley, W. Chris; Yoder, Mervin C.

2016-01-01

Alterations in the development of the placental vasculature can lead to pregnancy complications, such as preeclampsia. Currently, the cause of preeclampsia is unknown, and there are no specific prevention or treatment strategies. Further insight into the placental vasculature may aid in identifying causal factors. Endothelial colony-forming cells (ECFCs) are a subset of endothelial progenitor cells capable of self-renewal and de novo vessel formation in vitro. We hypothesized that ECFCs exist in the micro- and macrovasculature of the normal, term human placenta. Human placentas were collected from term pregnancies delivered by cesarean section (n = 16). Placental micro- and macrovasculature was collected from the maternal and fetal side of the placenta, respectively, and ECFCs were isolated and characterized. ECFCs were CD31+, CD105+, CD144+, CD146+, CD14−, and CD45−, took up 1,1′-dioctadecyl-3,3,3′,3′-tetramethyl-indocarbocyanine perchlorate-labeled acetylated low-density lipoprotein, and bound Ulex europaeus agglutinin 1. In vitro, macrovascular ECFCs had a greater potential to generate high-proliferative colonies and formed more complex capillary-like networks on Matrigel compared with microvascular ECFCs. In contrast, in vivo assessment demonstrated that microvascular ECFCs had a greater potential to form vessels. Macrovascular ECFCs were of fetal origin, whereas microvascular ECFCs were of maternal origin. ECFCs exist in the micro- and macrovasculature of the normal, term human placenta. Although macrovascular ECFCs demonstrated greater vessel and colony-forming potency in vitro, this did not translate in vivo, where microvascular ECFCs exhibited a greater vessel-forming ability. These important findings contribute to the current understanding of normal placental vascular development and may aid in identifying factors involved in preeclampsia and other pregnancy complications. Significance This research confirms that resident endothelial colony-forming cells (ECFCs) exist in the micro- and macrovasculature of the normal, term human placenta. Their isolation from two different anatomical locations yields two functionally different ECFC populations. Investigation of these ECFC populations during placental pathologies, such as preeclampsia, may lead to a better understanding of the disease process and aid in developing new therapies. PMID:26819255

microRNA in Human Reproduction.

PubMed

Eisenberg, Iris; Kotaja, Noora; Goldman-Wohl, Debra; Imbar, Tal

2015-01-01

microRNAs constitute a large family of approximately 21-nucleotide-long, noncoding RNAs. They emerged more than 20 years ago as key posttranscriptional regulators of gene expression. The regulatory role of these small RNA molecules has recently begun to be explored in the human reproductive system. microRNAs have been shown to play an important role in control of reproductive functions, especially in the processes of oocyte maturation, folliculogenesis, corpus luteum function, implantation, and early embryonic development. Knockout of Dicer, the cytoplasmic enzyme that cleaves the pre-miRNA to its mature form, results in postimplantation embryonic lethality in several animal models, attributing to these small RNA vital functions in reproduction and development. Another intriguing characteristic of microRNAs is their presence in body fluids in a remarkably stable form that is protected from endogenous RNase activity. In this chapter we will describe the current knowledge on microRNAs, specifically relating to human gonadal cells. We will focus on their role in the ovarian physiologic process and ovulation dysfunction, regulation of spermatogenesis and male fertility, and putative involvement in human normal and aberrant trophoblast differentiation and invasion through the process of placentation.

Drag reduction using metallic engineered surfaces with highly ordered hierarchical topographies: nanostructures on micro-riblets

NASA Astrophysics Data System (ADS)

Kim, Taekyung; Shin, Ryung; Jung, Myungki; Lee, Jinhyung; Park, Changsu; Kang, Shinill

2016-03-01

Durable drag-reduction surfaces have recently received much attention, due to energy-saving and power-consumption issues associated with harsh environment applications, such as those experienced by piping infrastructure, ships, aviation, underwater vehicles, and high-speed ground vehicles. In this study, a durable, metallic surface with highly ordered hierarchical structures was used to enhance drag-reduction properties, by combining two passive drag-reduction strategies: an air-layer effect induced by nanostructures and secondary vortex generation by micro-riblet structures. The nanostructures and micro-riblet structures were designed to increase slip length. The top-down fabrication method used to form the metallic hierarchical structures combined laser interference lithography, photolithography, thermal reflow, nanoimprinting, and pulse-reverse-current electrochemical deposition. The surfaces were formed from nickel, which has high hardness and corrosion resistance, making it suitable for use in harsh environments. The drag-reduction properties of various metal surfaces were investigated based on the surface structure: a bare surface, a nanostructured surface, a micro-riblet surface, and a hierarchically structured surface of nanostructures on micro-riblets.

Product asssurance requirements for micro VCM-apparatus and associated equipment

NASA Astrophysics Data System (ADS)

1982-10-01

The rules for performing Micro VCM-tests (vacuum tests) on materials for European Space Agency projects are presented. Formal guidelines for initial audits along with annual and special quality assurance reviews are summarized. Inspection forms are displayed.

A comparison study of nanofiber, microfiber, and new composite nano/microfiber polymers used as sorbents for on-line solid phase extraction in chromatography system.

PubMed

Háková, Martina; Havlíková, Lucie Chocholoušová; Chvojka, Jiří; Erben, Jakub; Solich, Petr; Švec, František; Šatínský, Dalibor

2018-09-06

Three different approaches has been used to obtain nano/micro fibers and their diversity and extraction properties were examined. The effect of their structure on stability in an ultra-high-performance liquid chromatography (UHPLC) system during on-line SPE procedure was monitored. Five types of various nano/micro fiber polymers were used as sorbents: polyamide 6 nanofibers, polyvinylidene difluoride nanofibers, polyethylene microfibers, and two new polycaprolactone microfiber/nanofiber and polycaprolactone microfibers/polyvinylidene difluoride nanofibers composite polymers. The fiber polymers were filled in a cartridge directly connected to the UHPLC system and tested. For each polymer, the optimal conditions of the on-line extraction were found and potential applicability on real samples was tested. The determination of ochratoxin A (OTA) in beer matrix was chosen as a case study. Relevant factors such as the mechanical and chemical stability of the nano/microfibers, filling the cartridges, fiber reusability and the possibility and the repeatability of all processes were involved in the proposed study. A new nano/micro composite sorbent consisting of polycaprolactone microfibers/polyvinylidene difluoride nanofibers was chosen as the most suitable sorbent for the on-line extraction of OTA from a beer matrix. The tested validation parameters had the value of intra-day precision lower than 1.48%, linearity in the range from 0.5 to 100 μg L -1 with r 2  ≥ 0.9999 for standard and matrix calibration curve, and recovery in the range 99.1-103.9% at five concentration levels. Long-term precision evaluated for 31 analyses over the period of three months did not exceed 2.9% RSD. It confirmed the column reusability and perfect stability of nano/micro composite sorbent in the presence of organic solvents and after repeated injection of a complex beer matrix. Copyright © 2018 Elsevier B.V. All rights reserved.

Efficient receptive field tiling in primate V1

PubMed Central

Nauhaus, Ian; Nielsen, Kristina J.; Callaway, Edward M.

2017-01-01

The primary visual cortex (V1) encodes a diverse set of visual features, including orientation, ocular dominance (OD) and spatial frequency (SF), whose joint organization must be precisely structured to optimize coverage within the retinotopic map. Prior experiments have only identified efficient coverage based on orthogonal maps. Here, we used two-photon calcium imaging to reveal an alternative arrangement for OD and SF maps in macaque V1; their gradients run parallel but with unique spatial periods, whereby low SF regions coincide with monocular regions. Next, we mapped receptive fields and find surprisingly precise micro-retinotopy that yields a smaller point-image and requires more efficient inter-map geometry, thus underscoring the significance of map relationships. While smooth retinotopy is constraining, studies suggest that it improves both wiring economy and the V1 population code read downstream. Altogether, these data indicate that connectivity within V1 is finely tuned and precise at the level of individual neurons. PMID:27499086

A precision device needs precise simulation: Software description of the CBM Silicon Tracking System

NASA Astrophysics Data System (ADS)

Malygina, Hanna; Friese, Volker; CBM Collaboration

2017-10-01

Precise modelling of detectors in simulations is the key to the understanding of their performance, which, in turn, is a prerequisite for the proper design choice and, later, for the achievement of valid physics results. In this report, we describe the implementation of the Silicon Tracking System (STS), the main tracking device of the CBM experiment, in the CBM software environment. The STS makes uses of double-sided silicon micro-strip sensors with double metal layers. We present a description of transport and detector response simulation, including all relevant physical effects like charge creation and drift, charge collection, cross-talk and digitization. Of particular importance and novelty is the description of the time behaviour of the detector, since its readout will not be externally triggered but continuous. We also cover some aspects of local reconstruction, which in the CBM case has to be performed in real-time and thus requires high-speed algorithms.

A New Threshold of Precision, 30 micro-arcsecond Parallaxes and Beyond

NASA Astrophysics Data System (ADS)

Riess, Adam

2017-08-01

The star formation histories of our nearest neighbors, M31 and theLMC, have been the subjects of intensive study but the 3% to 5%uncertainty in their distance limits knowledge of the ages of theirstructures to 0.6 to 1.0 Gyr. Two recent developments make it possibleto reach the previously unimaginable precision in distance of 1%. Thefirst is the development of DASH, which allows HST and WFC3 to slewtens of arcminutes between exposures within an orbit under gyrocontrol with enough precision to efficiently observe widelydistributed Cepheids.The second is the arrival of parallaxmeasurements from Gaia which are calibrating the individual distancesof long period Cepheids in the Milky Way to 2%. However, bandpass andzeropoint differences between ground and space observations wouldcompromise the precision of the Gaia parallaxes when building aCepheid bridge to our neighbors. We propose to dash around the LMC andM31 with WFC3 to rapidly collect 3 band photometry of over 70 longperiod Cepheids using the same photometric system as a calibration setof Cepheids in the Milky Way. These will nullify otherwise systematicerrors to extend the precision of Gaia beyond the Milky Way and clockthe formation of structures in M31 and the LMC to 100 Myr.

An experimental investigation of hydrodynamic cavitation in micro-Venturis

NASA Astrophysics Data System (ADS)

Mishra, Chandan; Peles, Yoav

2006-10-01

The existence of hydrodynamic cavitation in the flow of de-ionized water through micro-Venturis has been witnessed in the form of traveling bubble cavitation and fully developed streamer bubble/supercavitation, and their mechanisms have been discussed. High-speed photography and flow visualization disclose inchoate cavitation bubbles emerging downstream from the micro-Venturi throat and the presence of a single streamer bubble/supercavity, which is equidistant from the micro device walls. The supercavity initiates inside the diffuser section and extends until the microchannel exit and proceeds to bifurcate the incoming flow. This article strives to provide numerical data and experimental details of hydrodynamic cavitation taking place within micro-Venturis.

Parametric study of irradiation effects on the ductile damage and flow stress behavior in ferritic-martensitic steels

NASA Astrophysics Data System (ADS)

Chakraborty, Pritam; Biner, S. Bulent

2015-10-01

Ferritic-martensitic steels are currently being considered as structural materials in fusion and Gen-IV nuclear reactors. These materials are expected to experience high dose radiation, which can increase their ductile to brittle transition temperature and susceptibility to failure during operation. Hence, to estimate the safe operational life of the reactors, precise evaluation of the ductile to brittle transition temperatures of ferritic-martensitic steels is necessary. Owing to the scarcity of irradiated samples, particularly at high dose levels, micro-mechanistic models are being employed to predict the shifts in the ductile to brittle transition temperatures. These models consider the ductile damage evolution, in the form of nucleation, growth and coalescence of voids; and the brittle fracture, in the form of probabilistic cleavage initiation, to estimate the influence of irradiation on the ductile to brittle transition temperature. However, the assessment of irradiation dependent material parameters is challenging and influences the accuracy of these models. In the present study, the effects of irradiation on the overall flow stress and ductile damage behavior of two ferritic-martensitic steels is parametrically investigated. The results indicate that the ductile damage model parameters are mostly insensitive to irradiation levels at higher dose levels though the resulting flow stress behavior varies significantly.

Fully integrated and encapsulated micro-fabricated vacuum diode and method of manufacturing same

DOEpatents

Resnick, Paul J.; Langlois, Eric

2015-12-01

Disclosed is an encapsulated micro-diode and a method for producing same. The method comprises forming a plurality columns in the substrate with a respective tip disposed at a first end of the column, the tip defining a cathode of the diode; disposing a sacrificial oxide layer on the substrate, plurality of columns and respective tips; forming respective trenches in the sacrificial oxide layer around the columns; forming an opening in the sacrificial oxide layer to expose a portion of the tips; depositing a conductive material in of the opening and on a surface of the substrate to form an anode of the diode; and removing the sacrificial oxide layer.

Method of manufacturing a fully integrated and encapsulated micro-fabricated vacuum diode

DOEpatents

Resnick, Paul J.; Langlois, Eric

2014-08-26

Disclosed is an encapsulated micro-diode and a method for producing same. The method comprises forming a plurality columns in the substrate with a respective tip disposed at a first end of the column, the tip defining a cathode of the diode; disposing a sacrificial oxide layer on the substrate, plurality of columns and respective tips; forming respective trenches in the sacrificial oxide layer around the columns; forming an opening in the sacrificial oxide layer to expose a portion of the tips; depositing a conductive material in of the opening and on a surface of the substrate to form an anode of the diode; and removing the sacrificial oxide layer.

3D micro-mapping: Towards assessing the quality of crowdsourcing to support 3D point cloud analysis

NASA Astrophysics Data System (ADS)

Herfort, Benjamin; Höfle, Bernhard; Klonner, Carolin

2018-03-01

In this paper, we propose a method to crowdsource the task of complex three-dimensional information extraction from 3D point clouds. We design web-based 3D micro tasks tailored to assess segmented LiDAR point clouds of urban trees and investigate the quality of the approach in an empirical user study. Our results for three different experiments with increasing complexity indicate that a single crowdsourcing task can be solved in a very short time of less than five seconds on average. Furthermore, the results of our empirical case study reveal that the accuracy, sensitivity and precision of 3D crowdsourcing are high for most information extraction problems. For our first experiment (binary classification with single answer) we obtain an accuracy of 91%, a sensitivity of 95% and a precision of 92%. For the more complex tasks of the second Experiment 2 (multiple answer classification) the accuracy ranges from 65% to 99% depending on the label class. Regarding the third experiment - the determination of the crown base height of individual trees - our study highlights that crowdsourcing can be a tool to obtain values with even higher accuracy in comparison to an automated computer-based approach. Finally, we found out that the accuracy of the crowdsourced results for all experiments is hardly influenced by characteristics of the input point cloud data and of the users. Importantly, the results' accuracy can be estimated using agreement among volunteers as an intrinsic indicator, which makes a broad application of 3D micro-mapping very promising.

Data Identifiers, Versioning, and Micro-citation

NASA Astrophysics Data System (ADS)

Parsons, M. A.; Duerr, R. E.

2012-12-01

Data citation, especially using Digital Object Identifiers (DOIs), is an increasingly accepted scientific practice. For example, the AGU Council asserts that data "publications" should "be credited and cited like the products of any other scientific activity," and Thomson Reuters has recently announced a data citation index built from DOIs assigned to data sets. Correspondingly, formal guidelines for how to cite a data set (using DOIs or similar identifiers/locators) have recently emerged, notably those from the international DataCite consortium, the UK Digital Curation Centre, and the US Federation of Earth Science Information Partners. These different data citation guidelines are largely congruent. They agree on the basic practice and elements of data citation, especially for relatively static, whole data collections. There is less agreement on some of the more subtle nuances of data citation. They define different methods for handling different data set versions, especially for the very dynamic, growing data sets that are common in Earth Sciences. They also differ in how people should cite specific, arbitrarily large elements, "passages," or subsets of a larger data collection, i.e., the precise data records actually used in a study. This detailed "micro-citation", and careful reference to exact versions of data are essential to ensure scientific reproducibility. Identifiers such as DOIs are necessary but not sufficient for the precise, detailed, references necessary. Careful practice must be coupled with the use of curated identifiers. In this paper we review the pros and cons of different approaches to versioning and micro-citation. We suggest a workable solution for most existing Earth science data and suggest a more rigorous path forward for the future.

A parallel strategy for predicting the secondary structure of polycistronic microRNAs.

PubMed

Han, Dianwei; Tang, Guiliang; Zhang, Jun

2013-01-01

The biogenesis of a functional microRNA is largely dependent on the secondary structure of the microRNA precursor (pre-miRNA). Recently, it has been shown that microRNAs are present in the genome as the form of polycistronic transcriptional units in plants and animals. It will be important to design efficient computational methods to predict such structures for microRNA discovery and its applications in gene silencing. In this paper, we propose a parallel algorithm based on the master-slave architecture to predict the secondary structure from an input sequence. We conducted some experiments to verify the effectiveness of our parallel algorithm. The experimental results show that our algorithm is able to produce the optimal secondary structure of polycistronic microRNAs.

Direct fluorescence polarization assay for the detection of glycopeptide antibiotics.

PubMed

Yu, Linliang; Zhong, Meng; Wei, Yinan

2010-08-15

Glycopeptide antibiotics are widely used in the treatment of infections caused by Gram-positive bacteria. They inhibit the biosynthesis of the bacterial cell wall through binding to the D-alanyl-D-alanine (D-Ala-D-Ala) terminal peptide of the peptidoglycan precursor. Taking advantage of this highly specific interaction, we developed a direct fluorescence polarization based method for the detection of glycopeptide antibiotics. Briefly, we labeled the acetylated tripeptide Ac-L-Lys-D-Ala-D-Ala-OH with a fluorophore to create a peptide probe. Using three glycopeptide antibiotics, vancomycin, teicoplanin, and telavancin, as model compounds, we demonstrated that the fluorescence polarization of the peptide probe increased upon binding to antibiotics in a concentration dependent manner. The dissociation constants (K(d)) between the peptide probes and the antibiotics were consistent with those reported between free d-Ala-d-Ala and the antibiotics in the literature. The assay is highly reproducible and selective toward glycopeptide antibiotics. Its detection limit and work concentration range are 0.5 microM and 0.5-4 microM for vancomycin, 0.25 microM and 0.25-2 microM for teicoplanin, and 1 microM and 1-8 microM for telavancin. Furthermore, we compared our assay in parallel with a commercial fluorescence polarization immunoassay (FPIA) kit in detecting teicoplanin spiked in human blood samples. The accuracy and precision of the two methods are comparable. We expect our assay to be useful in both research and clinical laboratories.

Experimental investigation of the tip based micro/nano machining

NASA Astrophysics Data System (ADS)

Guo, Z.; Tian, Y.; Liu, X.; Wang, F.; Zhou, C.; Zhang, D.

2017-12-01

Based on the self-developed three dimensional micro/nano machining system, the effects of machining parameters and sample material on micro/nano machining are investigated. The micro/nano machining system is mainly composed of the probe system and micro/nano positioning stage. The former is applied to control the normal load and the latter is utilized to realize high precision motion in the xy plane. A sample examination method is firstly introduced to estimate whether the sample is placed horizontally. The machining parameters include scratching direction, speed, cycles, normal load and feed. According to the experimental results, the scratching depth is significantly affected by the normal load in all four defined scratching directions but is rarely influenced by the scratching speed. The increase of scratching cycle number can increase the scratching depth as well as smooth the groove wall. In addition, the scratching tests of silicon and copper attest that the harder material is easier to be removed. In the scratching with different feed amount, the machining results indicate that the machined depth increases as the feed reduces. Further, a cubic polynomial is used to fit the experimental results to predict the scratching depth. With the selected machining parameters of scratching direction d3/d4, scratching speed 5 μm/s and feed 0.06 μm, some more micro structures including stair, sinusoidal groove, Chinese character '田', 'TJU' and Chinese panda have been fabricated on the silicon substrate.

Generation of multiple Bessel beams for a biophotonics workstation.

PubMed

Cizmár, T; Kollárová, V; Tsampoula, X; Gunn-Moore, F; Sibbett, W; Bouchal, Z; Dholakia, K

2008-09-01

We present a simple method using an axicon and spatial light modulator to create multiple parallel Bessel beams and precisely control their individual positions in three dimensions. This technique is tested as an alternative to classical holographic beam shaping commonly used now in optical tweezers. Various applications of precise control of multiple Bessel beams are demonstrated within a single microscope giving rise to new methods for three-dimensional positional control of trapped particles or active sorting of micro-objects as well as "focus-free" photoporation of living cells. Overall this concept is termed a 'biophotonics workstation' where users may readily trap, sort and porate material using Bessel light modes in a microscope.

Timing module for MTCA MCH

NASA Astrophysics Data System (ADS)

Gumiński, M.; Kasprowicz, G.

2016-09-01

White Rabbit is an extension of Precise Time Protocol for synchronous Ethernet networks. Network created with dedicated WR switches enable synchronisation of WR capable devices with 1 ns precision. MicroTCA on the other hand is open standard defining cost efficient shelves capable of housing AMC modules used for data processing. Presented article give further introduction to WR and MTCA standard. The most important aspects of MTCA system are described, with focus on shelf controller and its functionality. Following part describes timing difficulties in MTCA systems and possible solutions. Main section describes extension module for MCH, capable of implementing White Rabbit node and distributing acquired timing to all modules connected to MTCA. Conclusions are given at the end of the article.

A minimalistic and optimized conveyor belt for neutral atoms.

PubMed

Roy, Ritayan; Condylis, Paul C; Prakash, Vindhiya; Sahagun, Daniel; Hessmo, Björn

2017-10-20

Here we report of a design and the performance of an optimized micro-fabricated conveyor belt for precise and adiabatic transportation of cold atoms. A theoretical model is presented to determine optimal currents in conductors used for the transportation. We experimentally demonstrate a fast adiabatic transportation of Rubidium ( 87 Rb) cold atoms with minimal loss and heating with as few as three conveyor belt conductors. This novel design of a multilayered conveyor belt structure is fabricated in aluminium nitride (AlN) because of its outstanding thermal and electrical properties. This demonstration would pave a way for a compact and portable quantum device required for quantum information processing and sensors, where precise positioning of cold atoms is desirable.

X-ray pore optic developments

NASA Astrophysics Data System (ADS)

Wallace, Kotska; Bavdaz, Marcos; Collon, Maximilien; Beijersbergen, Marco; Kraft, Stefan; Fairbend, Ray; Séguy, Julien; Blanquer, Pascal; Graue, Roland; Kampf, Dirk

2017-11-01

In support of future x-ray telescopes ESA is developing new optics for the x-ray regime. To date, mass and volume have made x-ray imaging technology prohibitive to planetary remote sensing imaging missions. And although highly successful, the mirror technology used on ESA's XMM-Newton is not sufficient for future, large, x-ray observatories, since physical limits on the mirror packing density mean that aperture size becomes prohibitive. To reduce telescope mass and volume the packing density of mirror shells must be reduced, whilst maintaining alignment and rigidity. Structures can also benefit from a modular optic arrangement. Pore optics are shown to meet these requirements. This paper will discuss two pore optic technologies under development, with examples of results from measurement campaigns on samples. One activity has centred on the use of coated, silicon wafers, patterned with ribs, that are integrated onto a mandrel whose form has been polished to the required shape. The wafers follow the shape precisely, forming pore sizes in the sub-mm region. Individual stacks of mirrors can be manufactured without risk to, or dependency on, each other and aligned in a structure from which they can also be removed without hazard. A breadboard is currently being built to demonstrate this technology. A second activity centres on glass pore optics. However an adaptation of micro channel plate technology to form square pores has resulted in a monolithic material that can be slumped into an optic form. Alignment and coating of two such plates produces an x-ray focusing optic. A breadboard 20cm aperture optic is currently being built.

Predicting Catastrophic BGP Routing Instabilities

DTIC Science & Technology

2004-03-01

predict a BGP routing instability confine their focus to either macro- or micro -level metrics, but not to both. The inherent limitations of each of...Level and Micro -Level Metrics Correlation; Worm Attack Studies; 16. PRICE CODE 17. SECURITY CLASSIFICATION OF REPORT Unclassified 18. SECURITY... micro -level metrics, but not to both. The inherent limitations of each of these forms of metric gives rise to an excessive rate of spurious alerts

Ultra short laser pulse modification of wave guides

NASA Astrophysics Data System (ADS)

Rosenfeld, Arkadi; Ashkenasi, David

2003-11-01

The high peak powers of ultra short (ps and sub-ps) pulsed lasers available at relatively low single pulse energies potentially allow for a precise localization of photon energy, either on the surface or inside (transparent) materials. Three dimensional micro structuring of bulk transparent media without any sign of mechanical cracking has shown the potential of ultra short laser processing. In this study, the micro structuring of bulk transparent media was used to modify fused silica and especially the cladding-core interface in normal fused silica wave guides. The idea behind this technique is to enforce a local mismatch for total reflection at the interface at minimal mechanic stress to overcome the barrier for enhanced optical out-coupling. The laser-induced modifications were studied in dependence of pulse width, focal alignment, single pulse energy and pulse overlap. Micro traces with a thickness between 3 and 8 μm were generated with a spacing of 10 μm in the subsurface region using sub-ps and ps laser pulses at a wavelength of 800 nm. The optical leakage enforced by a micro spiral pattern is significant and can be utilized for medical applications or potentially also for telecommunications and fiber laser technology.

Ultrashort laser pulse processing of wave guides for medical applications

NASA Astrophysics Data System (ADS)

Ashkenasi, David; Rosenfeld, Arkadi; Spaniol, Stefan B.; Terenji, Albert

2003-06-01

The availability of ultra short (ps and sub-ps) pulsed lasers has stimulated a growing interest in exploiting the enhanced flexibility of femtosecond and/or picosecond laser technology for micro-machining. The high peak powers available at relatively low single pulse energies potentially allow for a precise localization of photon energy, either on the surface or inside (transparent) materials. Three dimensional micro structuring of bulk transparent media without any sign of mechanical cracking has been demonstrated. In this study, the potential of ultra short laser processing was used to modify the cladding-core interface in normal fused silica wave guides. The idea behind this technique is to enforce a local mismatch for total reflection at the interface at minimal mechanic stress. The laser-induced modifications were studied in dependence of pulse width, focal alignment, single pulse energy and pulse overlap. Micro traces with a thickness between 3 and 8 μm were generated with a spacing of 10 μm in the sub-surface region using sub-ps and ps laser pulses at a wavelength of 800 nm. The optical leakage enforced by a micro spiral pattern is significant and can be utilized for medical applications or potentially also for telecommunications and fiber laser technology.

Preparation of uniform-sized multiple emulsions and micro/nano particulates for drug delivery by membrane emulsification.

PubMed

Liu, Wei; Yang, Xiang-Liang; Ho, W S Winston

2011-01-01

Much attention has in recent years been paid to fine applications of drug delivery systems, such as multiple emulsions, micro/nano solid lipid and polymer particles (spheres or capsules). Precise control of particle size and size distribution is especially important in such fine applications. Membrane emulsification can be used to prepare uniform-sized multiple emulsions and micro/nano particulates for drug delivery. It is a promising technique because of the better control of size and size distribution, the mildness of the process, the low energy consumption, easy operation and simple equipment, and amendable for large scale production. This review describes the state of the art of membrane emulsification in the preparation of monodisperse multiple emulsions and micro/nano particulates for drug delivery in recent years. The principles, influence of process parameters, advantages and disadvantages, and applications in preparing different types of drug delivery systems are reviewed. It can be concluded that the membrane emulsification technique in preparing emulsion/particulate products for drug delivery will further expand in the near future in conjunction with more basic investigations on this technique. Copyright © 2010 Wiley-Liss, Inc. and the American Pharmacists Association

A time-based front-end ASIC for the silicon micro strip sensors of the bar PANDA Micro Vertex Detector

NASA Astrophysics Data System (ADS)

Di Pietro, V.; Brinkmann, K.-Th.; Riccardi, A.; Ritman, J.; Rivetti, A.; Rolo, M. D.; Stockmanns, T.; Zambanini, A.

2016-03-01

The bar PANDA (Antiproton Annihilation at Darmstadt) experiment foresees many detectors for tracking, particle identification and calorimetry. Among them, the innermost is the MVD (Micro Vertex Detector) responsible for a precise tracking and the reconstruction of secondary vertices. This detector will be built from both hybrid pixel (two inner barrels and six forward disks) and double-sided micro strip (two outer barrels and outer rim of the last two disks) silicon sensors. A time-based approach has been chosen for the readout ASIC of the strip sensors. The PASTA (bar PANDA Strip ASIC) chip aims at high resolution time-stamping and charge information through the Time over Threshold (ToT) technique. It benefits from a Time to Digital Converter (TDC) allowing a time bin width down to 50 ps. The analog front-end was designed to serve both n-type and p-type strips and the performed simulations show remarkable performances in terms of linearity and electronic noise. The TDC consists of an analog interpolator, a digital local controller, and a digital global controller as the common back-end for all of the 64 channels.

Manufacture of high aspect ratio micro-pillar wall shear stress sensor arrays

NASA Astrophysics Data System (ADS)

Gnanamanickam, Ebenezer P.; Sullivan, John P.

2012-12-01

In the field of experimental fluid mechanics the measurement of unsteady, distributed wall shear stress has proved historically challenging. Recently, sensors based on an array of flexible micro-pillars have shown promise in carrying out such measurements. Similar sensors find use in other applications such as cellular mechanics. This work presents a manufacturing technique that can manufacture micro-pillar arrays of high aspect ratio. An electric discharge machine (EDM) is used to manufacture a micro-drilling tool. This micro-drilling tool is used to form holes in a wax sheet which acts as the mold for the micro-pillar array. Silicone rubber is cast in these molds to yield a micro-pillar array. Using this technique, micro-pillar arrays with a maximum aspect ratio of about 10 have been manufactured. Manufacturing issues encountered, steps to alleviate them and the potential of the process to manufacture similar micro-pillar arrays in a time-efficient manner are also discussed.