Science.gov

Sample records for micro vapor cells

  1. Precision micro drilling with copper vapor lasers

    SciTech Connect

    Chang, J.J.; Martinez, M.W.; Warner, B.E.; Dragon, E.P.; Huete, G.; Solarski, M.E.

    1994-09-02

    The authors have developed a copper vapor laser based micro machining system using advanced beam quality control and precision wavefront tilting technologies. Micro drilling has been demonstrated through percussion drilling and trepanning using this system. With a 30 W copper vapor laser running at multi-kHz pulse repetition frequency, straight parallel holes with size varying from 500 microns to less than 25 microns and with aspect ratio up to 1:40 have been consistently drilled on a variety of metals with good quality. For precision trepanned holes, the hole-to-hole size variation is typically within 1% of its diameter. Hole entrance and exit are both well defined with dimension error less than a few microns. Materialography of sectioned holes shows little (sub-micron scale) recast layer and heat affected zone with surface roughness within 1--2 microns.

  2. AMTEC vapor-vapor series connected cells

    NASA Technical Reports Server (NTRS)

    Underwood, Mark L. (Inventor); Williams, Roger M. (Inventor); Ryan, Margaret A. (Inventor); Nakamura, Barbara J. (Inventor); Oconnor, Dennis E. (Inventor)

    1995-01-01

    An alkali metal thermoelectric converter (AMTEC) having a plurality of cells structurally connected in series to form a septum dividing a plenum into two chambers, and electrically connected in series, is provided with porous metal anodes and porous metal cathodes in the cells. The cells may be planar or annular, and in either case a metal alkali vapor at a high temperature is provided to the plenum through one chamber on one side of the wall and returned to a vapor boiler after condensation at a chamber on the other side of the wall in the plenum. If the cells are annular, a heating core may be placed along the axis of the stacked cells. This arrangement of series-connected cells allows efficient generation of power at high voltage and low current.

  3. Vapor diffusion electrode improves fuel cell operation

    NASA Technical Reports Server (NTRS)

    Smith, J. O.

    1966-01-01

    Vapor diffusion type fuel cell electrode presents a nonwetting barrier to the liquid feedstocks so they may contact the electrolyte only in the vapor state. Thus, it effects feedstock mixing with the electrolyte at the electrolyte/catalyst interface but prevents feedstock decomposition and catalyst poisoning from liquid mingling.

  4. Improved cell for water-vapor electrolysis

    NASA Technical Reports Server (NTRS)

    Aylward, J. R.

    1981-01-01

    Continuous-flow electrolytic cells decompose water vapor in steam and room air into hydrogen and oxygen. Sintered iridium oxide catalytic anode coating yields dissociation rates hundredfold greater than those obtained using platinum black. Cell consists of two mirror-image cells, with dual cathode sandwiched between two anodes. Gas traverses serpentine channels within cell and is dissociated at anode. Oxygen mingles with gas stream, while hydrogen migrates through porous matrix and is liberated as gas at cathode.

  5. Integrating Sphere Alkali-Metal Vapor Cells

    NASA Astrophysics Data System (ADS)

    McGuyer, Bart; Ben-Kish, Amit; Jau, Yuan-Yu; Happer, William

    2010-03-01

    An integrating sphere is an optical multi-pass cavity that uses diffuse reflection to increase the optical path length. Typically applied in photometry and radiometry, integrating spheres have previously been used to detect trace gases and to cool and trap alkali-metal atoms. Here, we investigate the potential for integrating spheres to enhance optical absorption in optically thin alkali-metal vapor cells. In particular, we consider the importance of dielectric effects due to a glass container for the alkali-metal vapor. Potential applications include miniature atomic clocks and magnetometers, where multi-passing could reduce the operating temperature and power consumption.

  6. Micro-Tubular Fuel Cells

    NASA Technical Reports Server (NTRS)

    Kimble, Michael C.; Anderson, Everett B.; Jayne, Karen D.; Woodman, Alan S.

    2004-01-01

    Micro-tubular fuel cells that would operate at power levels on the order of hundreds of watts or less are under development as alternatives to batteries in numerous products - portable power tools, cellular telephones, laptop computers, portable television receivers, and small robotic vehicles, to name a few examples. Micro-tubular fuel cells exploit advances in the art of proton-exchange-membrane fuel cells. The main advantage of the micro-tubular fuel cells over the plate-and-frame fuel cells would be higher power densities: Whereas the mass and volume power densities of low-pressure hydrogen-and-oxygen-fuel plate-and-frame fuel cells designed to operate in the targeted power range are typically less than 0.1 W/g and 0.1 kW/L, micro-tubular fuel cells are expected to reach power densities much greater than 1 W/g and 1 kW/L. Because of their higher power densities, micro-tubular fuel cells would be better for powering portable equipment, and would be better suited to applications in which there are requirements for modularity to simplify maintenance or to facilitate scaling to higher power levels. The development of PEMFCs has conventionally focused on producing large stacks of cells that operate at typical power levels >5 kW. The usual approach taken to developing lower-power PEMFCs for applications like those listed above has been to simply shrink the basic plate-and-frame configuration to smaller dimensions. A conventional plate-and-frame fuel cell contains a membrane/electrode assembly in the form of a flat membrane with electrodes of the same active area bonded to both faces. In order to provide reactants to both electrodes, bipolar plates that contain flow passages are placed on both electrodes. The mass and volume overhead of the bipolar plates amounts to about 75 percent of the total mass and volume of a fuel-cell stack. Removing these bipolar plates in the micro-tubular fuel cell significantly increases the power density.

  7. Micro fuel cell

    SciTech Connect

    Zook, L.A.; Vanderborgh, N.E.; Hockaday, R.

    1998-12-31

    An ambient temperature, liquid feed, direct methanol fuel cell device is under development. A metal barrier layer was used to block methanol crossover from the anode to the cathode side while still allowing for the transport of protons from the anode to the cathode. A direct methanol fuel cell (DMFC) is an electrochemical engine that converts chemical energy into clean electrical power by the direct oxidation of methanol at the fuel cell anode. This direct use of a liquid fuel eliminates the need for a reformer to convert the fuel to hydrogen before it is fed into the fuel cell.

  8. A heated vapor cell unit for dichroic atomic vapor laser lock in atomic rubidium.

    PubMed

    McCarron, Daniel J; Hughes, Ifan G; Tierney, Patrick; Cornish, Simon L

    2007-09-01

    The design and performance of a compact heated vapor cell unit for realizing a dichroic atomic vapor laser lock (DAVLL) for the D(2) transitions in atomic rubidium is described. A 5 cm long vapor cell is placed in a double-solenoid arrangement to produce the required magnetic field; the heat from the solenoid is used to increase the vapor pressure and correspondingly the DAVLL signal. We have characterized experimentally the dependence of important features of the DAVLL signal on magnetic field and cell temperature. For the weaker transitions both the amplitude and gradient of the signal are increased by an order of magnitude. PMID:17902946

  9. Micro-ablation with high power pulsed copper vapor lasers.

    PubMed

    Knowles, M

    2000-07-17

    Visible and UV lasers with nanosecond pulse durations, diffraction-limited beam quality and high pulse repetition rates have demonstrated micro-ablation in a wide variety of materials with sub-micron precision and sub-micron-sized heat-affected zones. The copper vapour laser (CVL) is one of the important industrial lasers for micro-ablation applications. Manufacturing applications for the CVL include orifice drilling in fuel injection components and inkjet printers, micro-milling of micromoulds, via hole drilling in printed circuit boards and silicon machining. Recent advances in higher power (100W visible, 5W UV), diffraction-limited, compact CVLs are opening new possibilities for manufacturing with this class of nanosecond laser. PMID:19404369

  10. Micro cell isolation column for allergic diagnosis

    NASA Astrophysics Data System (ADS)

    Kobayashi, Koichiro; Sakamoto, Kenji; Yanase, Yuhki; Hide, Michihiro; Miyake, Ryo

    2016-03-01

    We suggest a new micro cell isolation column of basophils for an allergic diagnostic system for detecting human basophils activations. Surface plasmon resonance imaging (SPRI) biosensors using human basophils allow allergic diagnosis of less than 1 ml of peripheral blood. However, an isolation of basophils from a small amount of blood is not easy. In this study, we constructed a new micro cell isolation column for basophils with poly(dimethylsiloxane) (PDMS) microflow pass including magnetic particles. Furthermore, we determined whether leukocytes were captured by the micro cell isolation column from a small amount of blood. We can isolate basophils from other leukocytes by using the micro cell isolation column.

  11. Qualitative Evaluation of a Liquid-Vapor Separator Concept in Micro-Gravity Conditions

    NASA Astrophysics Data System (ADS)

    Elston, Levi J.; Yerkes, Kirk L.; Thomas, Scott K.; McQuillen, John

    2009-03-01

    An innovative liquid-vapor separator design has been incorporated into a spray cooling experiment, which was flown recently on the NASA C-9 reduced gravity aircraft. This design is the latest in a series of designs that have been flown in microgravity and elevated gravity in relation to an experimental investigation into spray cooling performance with regard to possible application to high-performance aircraft undergoing combat maneuvers. Initially, significant problems occurred during flight testing due to the inability of the reservoir to separate the liquid coolant from the vapor under microgravity conditions, which resulted in a loss of coolant to the simulated electronic device that was being spray cooled. Improvements in the design of the liquid-vapor separator are described in this paper, and experimental data showing the performance of several generations of liquid-vapor separators are presented. The final separator design went through more rigorous evaluation to compare performance at multiple fill levels, each with a higher percentage of vapor space within the reservoir. It was found that, using the final reservoir design, stable flow operation was achieved in micro-gravity for mass flowrates of m = 14, 17.5, and 21 [g/s].

  12. Vapor Corrosion Cell and Method of Using Same

    NASA Technical Reports Server (NTRS)

    Davis, Dennis D. (Inventor)

    2001-01-01

    The present invention provides a vapor corrosion cell for a real-time and quantitative measurement of corrosion of conductive materials in atmospheres containing chemically reactive gases and water vapor. Two prototypes are provided. Also provided are various applications of this apparatus in industry.

  13. Soft Micro-Channels for Cell Culturing and Migration Studies

    NASA Astrophysics Data System (ADS)

    Abbasirazgaleh, Sara

    Various techniques and methods have been studied and developed to aid nerve regeneration and repairing nerve injuries. Among all, nerve grafting is the gold standard for bridging the gap between the injured nerve stumps. Despite the advantages of this technique, there are also various drawbacks that have encouraged the exploration of alternative, less invasive methods for promoting nerve regeneration. In this thesis, we have fabricated soft micro-channels for cell culturing and migration studies which could act as an interface capable of long-term, reliable, and high-resolution stimulation device for nerve regeneration. Micro-channels fabrication is performed using a combination of photolithography technique and physical vapor deposition (PVD) methods. Initially, the surfaces of the micro-channels are treated with oxygen plasma to convert the surface of PDMS from hydrophobic to hydrophilic and to further provide an optimal environment for cells to adhere and grow. Next, in vitro studies were performed on the fabricated micro-channels to demonstrate feasibility of the platform to promote adherence and growth of PC12 cells (cell line derived from a pheochromocytomas of the rat adrenal medulla).

  14. Microfabricated atomic vapor cell arrays for magnetic field measurements

    SciTech Connect

    Woetzel, S.; Schultze, V.; IJsselsteijn, R.; Schulz, T.; Anders, S.; Stolz, R.; Meyer, H.-G.

    2011-03-15

    We describe a method for charging atomic vapor cells with cesium and buffer gas. By this, it is possible to adjust the buffer gas pressure in the cells with good accuracy. Furthermore, we present a new design of microfabricated vapor cell arrays, which combine silicon wafer based microfabrication and ultrasonic machining to achieve the arrays of thermally separated cells with 50 mm{sup 3} volume. With cells fabricated in the outlined way, intrinsic magnetic field sensitivities down to 300 fT/Hz{sup 1/2} are reached.

  15. High pressure studies using two-stage diamond micro-anvils grown by chemical vapor deposition

    DOE PAGESBeta

    Vohra, Yogesh K.; Samudrala, Gopi K.; Moore, Samuel L.; Montgomery, Jeffrey M.; Tsoi, Georgiy M.; Velisavljevic, Nenad

    2015-06-10

    Ultra-high static pressures have been achieved in the laboratory using a two-stage micro-ball nanodiamond anvils as well as a two-stage micro-paired diamond anvils machined using a focused ion-beam system. The two-stage diamond anvils’ designs implemented thus far suffer from a limitation of one diamond anvil sliding past another anvil at extreme conditions. We describe a new method of fabricating two-stage diamond micro-anvils using a tungsten mask on a standard diamond anvil followed by microwave plasma chemical vapor deposition (CVD) homoepitaxial diamond growth. A prototype two stage diamond anvil with 300 μm culet and with a CVD diamond second stage ofmore » 50 μm in diameter was fabricated. We have carried out preliminary high pressure X-ray diffraction studies on a sample of rare-earth metal lutetium sample with a copper pressure standard to 86 GPa. Furthermore, the micro-anvil grown by CVD remained intact during indentation of gasket as well as on decompression from the highest pressure of 86 GPa.« less

  16. High pressure studies using two-stage diamond micro-anvils grown by chemical vapor deposition

    SciTech Connect

    Vohra, Yogesh K.; Samudrala, Gopi K.; Moore, Samuel L.; Montgomery, Jeffrey M.; Tsoi, Georgiy M.; Velisavljevic, Nenad

    2015-06-10

    Ultra-high static pressures have been achieved in the laboratory using a two-stage micro-ball nanodiamond anvils as well as a two-stage micro-paired diamond anvils machined using a focused ion-beam system. The two-stage diamond anvils’ designs implemented thus far suffer from a limitation of one diamond anvil sliding past another anvil at extreme conditions. We describe a new method of fabricating two-stage diamond micro-anvils using a tungsten mask on a standard diamond anvil followed by microwave plasma chemical vapor deposition (CVD) homoepitaxial diamond growth. A prototype two stage diamond anvil with 300 μm culet and with a CVD diamond second stage of 50 μm in diameter was fabricated. We have carried out preliminary high pressure X-ray diffraction studies on a sample of rare-earth metal lutetium sample with a copper pressure standard to 86 GPa. Furthermore, the micro-anvil grown by CVD remained intact during indentation of gasket as well as on decompression from the highest pressure of 86 GPa.

  17. Fabrication and characterization of an electrically contacted vapor cell.

    PubMed

    Daschner, R; Ritter, R; Kübler, H; Frühauf, N; Kurz, E; Löw, R; Pfau, T

    2012-06-15

    We demonstrate the use of electrically contacted vapor cells to switch the transmission of a probe laser. The excitation scheme makes use of electromagnetically induced transparency involving a Rydberg state. The cell fabrication technique involves thin-film-based electric feedthroughs, which are well suited for scaling this concept to many addressable pixels like in flat panel displays. PMID:22739878

  18. Are endothelial cell bioeffects from acoustic droplet vaporization proximity dependent?

    NASA Astrophysics Data System (ADS)

    Seda, Robinson; Li, David; Fowlkes, J. Brian; Bull, Joseph

    2013-11-01

    Acoustic droplet vaporization (ADV) produces gas microbubbles that provide a means of selective occlusion in gas embolotherapy. Vaporization and subsequent occlusion occur inside blood vessels supplying the targeted tissue, such as tumors. Theoretical and computational studies showed that ADV within a vessel can impart high fluid mechanical stresses on the vessel wall. Previous in vitro studies have demonstrated that vaporization at an endothelial layer may affect cell attachment and viability. The current study is aimed at investigating the role of vaporization distance away from the endothelial layer. HUVECs were cultured in OptiCell™ chambers until reaching confluence. Dodecafluoropentane microdroplets were added, attaining a 10:1 droplet to cell ratio. A single ultrasound pulse (7.5 MHz) consisting of 16 cycles (~ 2 μs) and a 5 MPa peak rarefactional pressure was used to produce ADV while varying the vaporization distance from the endothelial layer (0 μm, 500 μm, 1000 μm). Results indicated that cell attachment and viability was significantly different if the distance was 0 μm (at the endothelial layer). Other distances were not significantly different from the control. ADV will significantly affect the endothelium if droplets are in direct contact with the cells. Droplet concentration and flow conditions inside blood vessels may play an important role. This work was supported by NIH grant R01EB006476.

  19. Growth of GaN micro/nanolaser arrays by chemical vapor deposition.

    PubMed

    Liu, Haitao; Zhang, Hanlu; Dong, Lin; Zhang, Yingjiu; Pan, Caofeng

    2016-09-01

    Optically pumped ultraviolet lasing at room temperature based on GaN microwire arrays with Fabry-Perot cavities is demonstrated. GaN microwires have been grown perpendicularly on c-GaN/sapphire substrates through simple catalyst-free chemical vapor deposition. The GaN microwires are [0001] oriented single-crystal structures with hexagonal cross sections, each with a diameter of ∼1 μm and a length of ∼15 μm. A possible growth mechanism of the vertical GaN microwire arrays is proposed. Furthermore, we report room-temperature lasing in optically pumped GaN microwire arrays based on the Fabry-Perot cavity. Photoluminescence spectra exhibit lasing typically at 372 nm with an excitation threshold of 410 kW cm(-2). The result indicates that these aligned GaN microwire arrays may offer promising prospects for ultraviolet-emitting micro/nanodevices. PMID:27454350

  20. Growth of GaN micro/nanolaser arrays by chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Liu, Haitao; Zhang, Hanlu; Dong, Lin; Zhang, Yingjiu; Pan, Caofeng

    2016-09-01

    Optically pumped ultraviolet lasing at room temperature based on GaN microwire arrays with Fabry–Perot cavities is demonstrated. GaN microwires have been grown perpendicularly on c-GaN/sapphire substrates through simple catalyst-free chemical vapor deposition. The GaN microwires are [0001] oriented single-crystal structures with hexagonal cross sections, each with a diameter of ∼1 μm and a length of ∼15 μm. A possible growth mechanism of the vertical GaN microwire arrays is proposed. Furthermore, we report room-temperature lasing in optically pumped GaN microwire arrays based on the Fabry–Perot cavity. Photoluminescence spectra exhibit lasing typically at 372 nm with an excitation threshold of 410 kW cm‑2. The result indicates that these aligned GaN microwire arrays may offer promising prospects for ultraviolet-emitting micro/nanodevices.

  1. Electromagnetically induced transparency in paraffin-coated vapor cells

    SciTech Connect

    Klein, M.; Hohensee, M.; Walsworth, R. L.; Phillips, D. F.

    2011-01-15

    Antirelaxation coatings in atomic vapor cells allow ground-state coherent spin states to survive many collisions with the cell walls. This reduction in the ground-state decoherence rate gives rise to ultranarrow-bandwidth features in electromagnetically induced transparency (EIT) spectra, which can form the basis of, for example, long-time scale slow and stored light, sensitive magnetometers, and precise frequency standards. Here we study, both experimentally and theoretically, how Zeeman EIT contrast and width in paraffin-coated rubidium vapor cells are determined by cell and laser-beam geometry, laser intensity, and atomic density. Using a picture of Ramsey pulse sequences, where atoms alternately spend ''bright'' and ''dark'' time intervals inside and outside the laser beam, we explain the behavior of EIT features in coated cells, highlighting their unique characteristics and potential applications.

  2. Scanning microwave microscope imaging of micro-patterned monolayer graphene grown by chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Myers, J.; Mou, S.; Chen, K.-H.; Zhuang, Y.

    2016-02-01

    Characterization of micro-patterned chemical vapor deposited monolayer graphene using a scanning microwave microscope has been presented. Monolayer graphene sheets deposited on a copper substrate were transferred to a variety of substrates and micro-patterned into a periodic array of parallel lines. The measured complex reflection coefficients exhibit a strong dependency on the operating frequency and on the samples' electrical conductivity and permittivity. The experiments show an extremely high sensitivity by detecting image contrast between single and double layer graphene sheets. Correlating the images recorded at the half- and quarter-wavelength resonant frequencies shows that the relative permittivity of the single layer graphene sheet is above 105. The results are in good agreement with the three dimensional numerical electromagnetic simulations. This method may be instrumental for a comprehensive understanding of the scanning microwave microscope image contrast and provide a unique technique to estimate the local electrical properties with nano-meter scale spatial resolution of two dimensional materials at radio frequency.

  3. Static Pressure Above 300 GPa Using Chemical Vapor Deposited Two-stage Diamond Micro-anvils

    NASA Astrophysics Data System (ADS)

    Montgomery, Jeffrey; Samudrala, Gopi; Tsoi, Georgiy; Smith, Spencer; Vohra, Yogesh

    Two-stage diamond micro-anvils were grown via chemical vapor deposition (CVD) on beveled diamond anvils with 30 micron central flats. These anvils were used to compress a pre-indented rhenium foil to pressures in excess of 300 Gigapascals (GPa) at relatively small applied loads. Powder diffraction patterns were collected across the high-pressure region using an x-ray beam collimated to 1x2 microns in a grid with a spacing of 1 micron. While multi-megabar pressures were seen across the entire second stage, the highest pressure regions were confined to areas of a few microns in diameter. These were observed at points near the edge of the second stage with nearby pressure gradients as high as 100 GPa/micron. The transmitted x-rays show that the second stage plastically deformed while maintaining multi-megabar pressures. This may have created a second-stage gasket consisting of CVD diamond and rhenium that supported the pressure gradient without substantial external confining pressure. Further improvements in two-stage diamond micro-anvils would require controlling the geometry and microcrystalline/nanocrystalline diamond content during CVD growth process. This work was supported by the Department of Energy (DOE), National Nuclear Security Administration under Grant Number DE-NA0002014.

  4. Thermal behavior of silicon-copper micro vapor chamber for high power LEDs

    NASA Astrophysics Data System (ADS)

    Luo, Yi; Li, Zhi-xin; Zhou, Chuan-peng; Wang, Xiao-dong; You, Bo

    2016-03-01

    Micro vapor chamber (MVC) for light emitting diodes (LEDs) can be designed and fabricated to enhance the heat dissipation efficiency and improve the reliability. In this paper, we used photoresist SU-8 and electroforming copper (Cu) to fabricate three kinds of wick structures, which are star, radiation and parallel ones, and the substrate is silicon with thickness of 0.5 mm. Electroforming Cu on silicon to make micro wick structure was a critical step, the ampere-hour factor was used, and accordingly the electroforming time was predicted. The composition of electroforming solution and parameters of electroforming were optimized too. After charging and packaging, thermal behavior tests were carried out to study the heat dissipation performance of MVCs. When the input power was 8 W, the parallel wick structure reached the equivalent temperature of 69.0 °C in 226 s, while the others were higher than that. The experimental results prove that the wick structures have significant influence on the heat transfer capability of MVCs.

  5. Electrolysis cell functions as water vapor dehumidifier and oxygen generator

    NASA Technical Reports Server (NTRS)

    Clifford, J. E.

    1971-01-01

    Water vapor is absorbed in hygroscopic electrolyte, and oxygen generated by absorbed water electrolysis at anode is added simultaneously to air stream. Cell applications include on-board aircraft oxygen systems, portable oxygen generators, oxygen concentration requirements, and commercial air conditioning and dehumidifying systems.

  6. Reactive vaporization of oxides in solid oxide fuel cell systems

    NASA Astrophysics Data System (ADS)

    Key, Camas Fought

    Metals such as chromium, aluminum and silicon are of extreme technological and industrial importance due to the corrosion resistance they offer in oxidizing environments at high temperature. Much of this robustness is based on the formation of a thin, well-adhered metal-oxide (MO) layer on the surface of the metal. In particularly corrosive environments or at high-enough temperatures and or pressures, the MO will chemically react with constituents in the surrounding gas, removing atoms from the solid. For many systems, material loss and subsequent mechanical failure is the foremost concern. However, in solid oxide fuel cell (SOFC) systems, the presence of gaseous metal species leads to severe degradation in electrochemical performance well before mechanical limits are reached. Reactive vaporization from ferritic stainless steels, chromia, aluminosilicates and a candidate electrode material (Sr2VMoO6), was investigated using the transpiration method. Two novel collection methods were employed: condensation of vapors on wafer collectors analyzed with Rutherford backscattering spectrometry (RBS); and, condensation of vapors on quartz wool analyzed via inductively coupled plasma mass spectroscopy (ICP-MS). Identification and quantification of vapor species provided assessment of material performance in SOFC environments. Experiments demonstrated that Cr vapor species from ferritic stainless steels used for SOFC interconnect applications could be reduced by as much as one order of magnitude through the application of barrier coatings. Base alloys were compared and exhibited a variety of Cr vaporization rates despite being similar in composition, thus illustrating the importance of minor elemental constituents in the alloy. Measurements identified Si as the primary volatile element in aluminosilicate materials when Si concentrations in the bulk material were as low as one percent. Aluminosilicate materials demonstrated a burn out phase during the first hundred hours at

  7. In-membrane micro fuel cell

    DOEpatents

    Omosebi, Ayokunle; Besser, Ronald

    2016-09-06

    An in-membrane micro fuel cell comprises an electrically-insulating membrane that is permissive to the flow of cations, such as protons, and a pair of electrodes deposited on channels formed in the membrane. The channels are arranged as conduits for fluids, and define a membrane ridge between the channels. The electrodes are porous and include catalysts for promoting the liberation of a proton and an electron from a chemical species and/or or the recombination of a proton and an electron with a chemical specie. The fuel cell may be provided a biosensor, an electrochemical sensor, a microfluidic device, or other microscale devices fabricated in the fuel cell membrane.

  8. Radio-frequency-modulated Rydberg states in a vapor cell

    NASA Astrophysics Data System (ADS)

    Miller, S. A.; Anderson, D. A.; Raithel, G.

    2016-05-01

    We measure strong radio-frequency (RF) electric fields using rubidium Rydberg atoms prepared in a room-temperature vapor cell as field sensors. Electromagnetically induced transparency is employed as an optical readout. We RF-modulate the 60{{{S}}}1/2 and 58{{{D}}}5/2 Rydberg states with 50 and 100 MHz fields, respectively. For weak to moderate RF fields, the Rydberg levels become Stark-shifted, and sidebands appear at even multiples of the driving frequency. In high fields, the adjacent hydrogenic manifold begins to intersect the shifted levels, providing rich spectroscopic structure suitable for precision field measurements. A quantitative description of strong-field level modulation and mixing of S and D states with hydrogenic states is provided by Floquet theory. Additionally, we estimate the shielding of DC electric fields in the interior of the glass vapor cell.

  9. Faraday rotation spectroscopy in multi-pass atomic vapor cells

    NASA Astrophysics Data System (ADS)

    Li, Shuguang; Vachaspati, Pranjal; Dural, Nezih; Romalis, Michael

    2011-05-01

    Many important applications of atomic vapors, such as quantum measurements, light storage experiments, and atomic magnetometers benefit from large optical depth of the atomic ensemble. We explore multi-pass cells using cylindrical mirrors with a hole for the entrance and exit of the laser beam to achieve very high optical depth while sampling a large number of atoms. Such cells are much less sensitive to mirror quality and alignment compared to optical cavities and do not require laser frequency locking, mode matching or power coupling matching. Cells with more than 100 passes have been fabricated using internal high-reflectivity mirrors. We have performed paramagnetic Faraday rotation measurements on Rb vapor and have observed atomic rotation angles in excess of 60 radians. Quantum spin noise from unpolarized atomic vapor has also been observed with a high signal-to-noise ratio. This system also exhibits non-linear spin relaxation due to spin-exchange collisions, opening the possibility of using spin-squeezing techniques to improve long-term sensitivity of frequency measurements. We will report on the development of a scalar atomic magnetometer using such spin-squeezing techniques.

  10. Optical pumping in a microfabricated Rb vapor cell using a microfabricated Rb discharge light source

    SciTech Connect

    Venkatraman, V.; Kang, S.; Affolderbach, C.; Mileti, G.; Shea, H.

    2014-02-03

    Miniature (vapor-cell based devices using optical pumping of alkali atoms, such as atomic clocks and magnetometers, today mostly employ vertical-cavity surface-emitting lasers as pump light sources. Here, we report on the demonstration of optical pumping in a microfabricated alkali vapor resonance cell using (1) a microfabricated Rb discharge lamp light source, as well as (2) a conventional glass-blown Rb discharge lamp. The microfabricated Rb lamp cell is a dielectric barrier discharge (DBD) light source, having the same inner cell volume of around 40 mm{sup 3} as that of the resonance cell, both filled with suitable buffer gases. A miniature (∼2 cm{sup 3} volume) test setup based on the M{sub z} magnetometer interrogation technique was used for observation of optical-radiofrequency double-resonance signals, proving the suitability of the microfabricated discharge lamp to introduce efficient optical pumping. The pumping ability of this light source was found to be comparable to or even better than that of a conventional glass-blown lamp. The reported results indicate that the micro-fabricated DBD discharge lamp has a high potential for the development of a new class of miniature atomic clocks, magnetometers, and quantum sensors.

  11. Low-temperature indium-bonded alkali vapor cell for chip-scale atomic clocks

    NASA Astrophysics Data System (ADS)

    Straessle, R.; Pellaton, M.; Affolderbach, C.; Pétremand, Y.; Briand, D.; Mileti, G.; de Rooij, N. F.

    2013-02-01

    A low-temperature sealing technique for micro-fabricated alkali vapor cells for chip-scale atomic clock applications is developed and evaluated. A thin-film indium bonding technique was used for sealing the cells at temperatures of ≤140 °C. These sealing temperatures are much lower than those reported for other approaches, and make the technique highly interesting for future micro-fabricated cells, using anti-relaxation wall coatings. Optical and microwave spectroscopy performed on first indium-bonded cells without wall coatings are used to evaluate the cleanliness of the process as well as a potential leak rate of the cells. Both measurements confirm a stable pressure inside the cell and therefore an excellent hermeticity of the indium bonding. The double-resonance measurements performed over several months show an upper limit for the leak rate of 1.5 × 10-13 mbar.l/s. This is in agreement with additional leak-rate measurements using a membrane deflection method on indium-bonded test structures.

  12. Fabrication of solid oxide fuel cell by electrochemical vapor deposition

    DOEpatents

    Riley, B.; Szreders, B.E.

    1988-04-26

    In a high temperature solid oxide fuel cell (SOFC), the deposition of an impervious high density thin layer of electrically conductive interconnector material, such as magnesium doped lanthanum chromite, and of an electrolyte material, such as yttria stabilized zirconia, onto a porous support/air electrode substrate surface is carried out at high temperatures (/approximately/1100/degree/ /minus/ 1300/degree/C) by a process of electrochemical vapor deposition. In this process, the mixed chlorides of the specific metals involved react in the gaseous state with water vapor resulting in the deposit of an impervious thin oxide layer on the support tube/air electrode substrate of between 20--50 microns in thickness. An internal heater, such as a heat pipe, is placed within the support tube/air electrode substrate and induces a uniform temperature profile therein so as to afford precise and uniform oxide deposition kinetics in an arrangement which is particularly adapted for large scale, commercial fabrication of SOFCs.

  13. Fabrication of solid oxide fuel cell by electrochemical vapor deposition

    DOEpatents

    Brian, Riley; Szreders, Bernard E.

    1989-01-01

    In a high temperature solid oxide fuel cell (SOFC), the deposition of an impervious high density thin layer of electrically conductive interconnector material, such as magnesium doped lanthanum chromite, and of an electrolyte material, such as yttria stabilized zirconia, onto a porous support/air electrode substrate surface is carried out at high temperatures (approximately 1100.degree.-1300.degree. C.) by a process of electrochemical vapor deposition. In this process, the mixed chlorides of the specific metals involved react in the gaseous state with water vapor resulting in the deposit of an impervious thin oxide layer on the support tube/air electrode substrate of between 20-50 microns in thickness. An internal heater, such as a heat pipe, is placed within the support tube/air electrode substrate and induces a uniform temperature profile therein so as to afford precise and uniform oxide deposition kinetics in an arrangement which is particularly adapted for large scale, commercial fabrication of SOFCs.

  14. Fabrication of solid oxide fuel cell by electrochemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Riley, Brian; Szreders, Bernard E.

    1988-04-01

    In a high temperature solid oxide fuel cell (SOFC), the deposition of an impervious high density thin layer of electrically conductive interconnector material, such as magnesium doped lanthanum chromite, and of an electrolyte material, such as yttria stabilized zirconia, onto a porous support/air electrode substrate surface is carried out at high temperatures (approx. 1100 to 1300 C) by a process of electrochemical vapor deposition. In this process, the mixed chlorides of the specific metals involved react in the gaseous state with water vapor resulting in the deposit of an impervious thin oxide layer on the support tube/air electrode substrate of between 20 and 50 microns in thickness. An internal heater, such as a heat pipe, is placed within the support tube/air electrode substrate and induces a uniform temperature profile therein so as to afford precise and uniform oxide deposition kinetics in an arrangement which is particularly adapted for large scale, commercial fabrication of SOFCs.

  15. Enhancing vapor generation at a liquid-solid interface using micro/nanoscale surface structures fabricated by femtosecond laser surface processing

    NASA Astrophysics Data System (ADS)

    Anderson, Troy P.; Wilson, Chris; Zuhlke, Craig A.; Kruse, Corey; Gogos, George; Ndao, Sidy; Alexander, Dennis

    2015-03-01

    Femtosecond Laser Surface Processing (FLSP) is a versatile technique for the fabrication of a wide variety of micro/nanostructured surfaces with tailored physical and chemical properties. Through control over processing conditions such as laser fluence, incident pulse count, polarization, and incident angle, the size and density of both micrometer and nanometer-scale surface features can be tailored. Furthermore, the composition and pressure of the environment both during and after laser processing have a substantial impact on the final surface chemistry of the target material. FLSP is therefore a powerful tool for optimizing interfacial phenomena such as wetting, wicking, and phasetransitions associated with a vapor/liquid/solid interface. In the present study, we utilize a series of multiscale FLSPgenerated surfaces to improve the efficiency of vapor generation on a structured surface. Specifically, we demonstrate that FLSP of stainless steel 316 electrode surfaces in an alkaline electrolysis cell results in increased efficiency of the water-splitting reaction used to generate hydrogen. The electrodes are fabricated to be superhydrophilic (the contact angle of a water droplet on the surface is less than 5 degrees). The overpotential of the hydrogen evolution reaction (HER) is measured using a 3-electrode configuration with a structured electrode as the working electrode. The enhancement is attributed to several factors including increased surface area, increased wettability, and the impact of micro/nanostructures on the bubble formation and release. Special emphasis is placed on identifying and isolating the relative impacts of the various contributions.

  16. Microfabricated alkali vapor cell with anti-relaxation wall coating

    SciTech Connect

    Straessle, R.; Pétremand, Y.; Briand, D.; Rooij, N. F. de; Pellaton, M.; Affolderbach, C.; Mileti, G.

    2014-07-28

    We present a microfabricated alkali vapor cell equipped with an anti-relaxation wall coating. The anti-relaxation coating used is octadecyltrichlorosilane and the cell was sealed by thin-film indium-bonding at a low temperature of 140 °C. The cell body is made of silicon and Pyrex and features a double-chamber design. Depolarizing properties due to liquid Rb droplets are avoided by confining the Rb droplets to one chamber only. Optical and microwave spectroscopy performed on this wall-coated cell are used to evaluate the cell's relaxation properties and a potential gas contamination. Double-resonance signals obtained from the cell show an intrinsic linewidth that is significantly lower than the linewidth that would be expected in case the cell had no wall coating but only contained a buffer-gas contamination on the level measured by optical spectroscopy. Combined with further experimental evidence this proves the presence of a working anti-relaxation wall coating in the cell. Such cells are of interest for applications in miniature atomic clocks, magnetometers, and other quantum sensors.

  17. microRNAs: key triggers of neuronal cell fate

    PubMed Central

    Meza-Sosa, Karla F.; Pedraza-Alva, Gustavo; Pérez-Martínez, Leonor

    2014-01-01

    Development of the central nervous system (CNS) requires a precisely coordinated series of events. During embryonic development, different intra- and extracellular signals stimulate neural stem cells to become neural progenitors, which eventually irreversibly exit from the cell cycle to begin the first stage of neurogenesis. However, before this event occurs, the self-renewal and proliferative capacities of neural stem cells and neural progenitors must be tightly regulated. Accordingly, the participation of various evolutionary conserved microRNAs is key in distinct central nervous system (CNS) developmental processes of many organisms including human, mouse, chicken, frog, and zebrafish. microRNAs specifically recognize and regulate the expression of target mRNAs by sequence complementarity within the mRNAs 3′ untranslated region and importantly, a single microRNA can have several target mRNAs to regulate a process; likewise, a unique mRNA can be targeted by more than one microRNA. Thus, by regulating different target genes, microRNAs let-7, microRNA-124, and microRNA-9 have been shown to promote the differentiation of neural stem cells and neural progenitors into specific neural cell types while microRNA-134, microRNA-25 and microRNA-137 have been characterized as microRNAs that induce the proliferation of neural stem cells and neural progenitors. Here we review the mechanisms of action of these two sets of microRNAs and their functional implications during the transition from neural stem cells and neural progenitors to fully differentiated neurons. The genetic and epigenetic mechanisms that regulate the expression of these microRNAs as well as the role of the recently described natural RNA circles which act as natural microRNA sponges regulating post-transcriptional microRNA expression and function during the early stages of neurogenesis is also discussed. PMID:25009466

  18. Sub-picotesla Scalar Atomic Magnetometer with a Microfabricated Vapor Cell

    NASA Astrophysics Data System (ADS)

    Zhang, Rui; Mhaskar, Rahul

    2016-05-01

    We explore the sensitivity limits of scalar atomic magnetometry with a micro-fabricated Cs vapor cell. The millimeter-scale cell is fabricated using silicon Micro-Electro-Mechanical Systems (MEMS) technology. The atomic spin procession is driven by an amplitude-modulated circularly polarized pump laser resonant with the D1 transition in Cs atoms. The precession is detected by an off-resonant linearly polarized probe laser using a balanced polarimeter setup. The probe light is spatially split into two beams to perform a gradiometer measurement. In a magnetic field of magnitude within the range of the earth magnetic field, we measure a sensitivity of less than 150 fT/ √Hz in the gradiometer mode, which shows that the magnetometer by itself can achieve sub-100 fT/ √Hz sensitivitiy. In addition to its high sensitivity, the magnetometer has a bandwidth of nearly 1 kHz due to the broad magnetic resonance inside the small cell. Our experiment suggests the feasibility of a portable, low-power and high-performance magnetometer, which can be operated in the earth's magnetic field. Such a device will greatly expand the range of applications for atomic magnetometers, such as the detection of nuclear magnetic resonance in an unshielded environment.

  19. Electrode kinetics of a water vapor electrolysis cell

    NASA Technical Reports Server (NTRS)

    Jacobs, G.

    1974-01-01

    The anodic electrochemical behavior of the water vapor electrolysis cell was investigated. A theoretical review of various aspects of cell overvoltage is presented with special emphasis on concentration overvoltage and activation overvoltage. Other sources of overvoltage are described. The experimental apparatus controlled and measured anode potential and cell current. Potentials between 1.10 and 2.60 V (vs NHE) and currents between 0.1 and 3000 mA were investigated. Different behavior was observed between the standard cell and the free electrolyte cell. The free electrolyte cell followed typical Tafel behavior (i.e. activation overvoltage) with Tafel slopes of about 0.15, and the exchange current densities of 10 to the minus 9th power A/sq cm, both in good agreement with literature values. The standard cell exhibitied this same Tafel behavior at lower current densities but deviated toward lower than expected current densities at higher potentials. This behavior and other results were examined to determine their origin.

  20. Thin film solar cells grown by organic vapor phase deposition

    NASA Astrophysics Data System (ADS)

    Yang, Fan

    Organic solar cells have the potential to provide low-cost photovoltaic devices as a clean and renewable energy resource. In this thesis, we focus on understanding the energy conversion process in organic solar cells, and improving the power conversion efficiencies via controlled growth of organic nanostructures. First, we explain the unique optical and electrical properties of organic materials used for photovoltaics, and the excitonic energy conversion process in donor-acceptor heterojunction solar cells that place several limiting factors of their power conversion efficiency. Then, strategies for improving exciton diffusion and carrier collection are analyzed using dynamical Monte Carlo models for several nanostructure morphologies. Organic vapor phase deposition is used for controlling materials crystallization and film morphology. We improve the exciton diffusion efficiency while maintaining good carrier conduction in a bulk heterojunction solar cell. Further efficiency improvement is obtained in a novel nanocrystalline network structure with a thick absorbing layer, leading to the demonstration of an organic solar cell with 4.6% efficiency. In addition, solar cells using simultaneously active heterojunctions with broad spectral response are presented. We also analyze the efficiency limits of single and multiple junction organic solar cells, and discuss the challenges facing their practical implementations.

  1. FUEL CELL/MICRO-TURBINE COMBINED CYCLE

    SciTech Connect

    Larry J. Chaney; Mike R. Tharp; Tom W. Wolf; Tim A. Fuller; Joe J. Hartvigson

    1999-12-01

    A wide variety of conceptual design studies have been conducted that describe ultra-high efficiency fossil power plant cycles. The most promising of these ultra-high efficiency cycles incorporate high temperature fuel cells with a gas turbine. Combining fuel cells with a gas turbine increases overall cycle efficiency while reducing per kilowatt emissions. This study has demonstrated that the unique approach taken to combining a fuel cell and gas turbine has both technical and economic merit. The approach used in this study eliminates most of the gas turbine integration problems associated with hybrid fuel cell turbine systems. By using a micro-turbine, and a non-pressurized fuel cell the total system size (kW) and complexity has been reduced substantially from those presented in other studies, while maintaining over 70% efficiency. The reduced system size can be particularly attractive in the deregulated electrical generation/distribution environment where the market may not demand multi-megawatt central stations systems. The small size also opens up the niche markets to this high efficiency, low emission electrical generation option.

  2. Morphology of Imidazolium-Based Ionic Liquids as Deposited by Vapor Deposition: Micro-/Nanodroplets and Thin Films.

    PubMed

    Costa, José C S; Mendes, Adélio; Santos, Luís M N B F

    2016-07-18

    The morphology of micro- and nanodroplets and thin films of ionic liquids (ILs) prepared through physical vapor deposition is presented. The morphology of droplets deposited on indium-tin-oxide-coated glass is presented for the extended 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Cn C1 im][Ntf2 ]; n=1-8) series, and the results show the nanostructuration of ILs. The use of in-vacuum energetic particles enhances/increases the nanodroplets mobility/coalescence mechanisms and can be a pathway to the fabrication of thin IL films. PMID:27028765

  3. Laser-drilled micro-hole arrays on polyurethane synthetic leather for improvement of water vapor permeability

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Wang, A. H.; Zheng, R. R.; Tang, H. Q.; Qi, X. Y.; Ye, B.

    2014-06-01

    Three kinds of lasers at 1064, 532 and 355 nm wavelengths respectively were adopted to construct micro-hole arrays on polyurethane (PU) synthetic leather with an aim to improve water vapor permeability (WVP) of PU synthetic leather. The morphology of the laser-drilled micro-holes was observed to optimize laser parameters. The WVP and slit tear resistance of the laser-drilled leather were measured. Results show that the optimized pulse energy for the 1064, 532 and 355 nm lasers are 0.8, 1.1 and 0.26 mJ, respectively. The diameters of the micro-holes drilled with the optimized laser pulse energy were about 20, 15 and 10 μm, respectively. The depths of the micro-holes drilled with the optimized pulse energy were about 21, 60 and 69 μm, respectively. Compared with the untreated samples, the highest WVP growth ratio was 38.4%, 46.8% and 53.5% achieved by the 1064, 532 and 355 nm lasers, respectively. And the highest decreasing ratio of slit tear resistance was 11.1%, 14.8%, and 22.5% treated by the 1064, 532 and 355 nm lasers, respectively. Analysis of the interaction mechanism between laser beams at three kinds of laser wavelengths and the PU synthetic leather revealed that laser micro-drilling at 355 nm wavelength displayed both photochemical ablation and photothermal ablation, while laser micro-drilling at 1064 and 532 nm wavelengths leaded to photothermal ablation only.

  4. Influence of the Joule-Thomson effect on the flow of a vapor through a micro-porous membrane

    NASA Astrophysics Data System (ADS)

    Loimer, Thomas

    2005-11-01

    The flow of a fluid near saturation through a micro-porous membrane is considered. Upstream of the membrane, the fluid is in a state of saturated vapor. Downstreams, there is unsaturated vapor which is, due to the Joule-Thomson effect, cooler than at the upstream side. The flow is described taking into account the Joule-Thomson effect and the wetting properties between the fluid and the membrane material, i.e., the capillary pressure across a curved meniscus and capillary condensation. Different types of flow occur, depending on the permeability of the membrane, on the wetting properties between the fluid and the membrane and on the pressure difference. The fluid condenses either fully or partially at the front surface of the membrane, or a liquid film forms in front of the membrane. Liquid or a two-phase mixture flows through a part or all of the membrane and evaporates either within the membrane or at the downstream front of the membrane, or the fluid evaporates at the upstream front of the membrane and vapor flows through the entire membrane. The different types of flow are discussed and the conditions under which they occur are presented.

  5. Study of Rb-vapor coated cells — Atomic diffusion and cell curing process

    NASA Astrophysics Data System (ADS)

    Atutov, S. N.; Benimetskiy, F. A.; Plekhanov, A. I.; Sorokin, V. A.

    2016-02-01

    We present the results of a study on an optical-resonant cell filled by a vapor of the Rb atoms and coated with a non-stick polydimethylsiloxane (PDMS) polymer. We show that it is possible to define correctly the diffusion coefficient of the atoms in the coating using the geometric parameters of the cell and the vapor density in the cell volume only. The dependence of the diffusion coefficient on the cell curing time is presented. It is shown that the mysterious cell curing process can be explained in terms of the polymerization of the polymer coating by alkali atoms. The anomalous long dwell time of the Rb atoms on the PDMS coating is discussed as well.

  6. CONCISE REVIEW Micro RNA Expression in Multipotent Mesenchymal Stromal Cells

    PubMed Central

    Lakshmipathy, Uma; Hart, Ronald P.

    2009-01-01

    Multipotent mesenchymal stromal cells (MSC) isolated from various adult tissue sources have the capacity to self-renew and to differentiate into multiple lineages. Both of these processes are tightly regulated by genetic and epigenetic mechanisms. Emerging evidence indicates that the class of single-stranded non-coding RNAs known as “microRNAs” also plays a critical role in this process. First described in nematodes and plants, microRNAs have been shown to modulate major regulatory mechanisms in eukaryotic cells involved in a broad array of cellular functions. Studies with various types of embryonic as well as adult stem cells indicate an intricate network of microRNAs regulating key transcription factors and other genes which in turn determine cell fate. In addition, expression of unique microRNAs in specific cell types serves as a useful diagnostic marker to define a particular cell type. MicroRNAs are also found to be regulated by extracellular signaling pathways that are important for differentiation into specific tissues, suggesting that they play a role in specifying tissue identity. In this review we describe the importance of microRNAs in stem cells focusing on our current understanding of microRNAs in MSC and their derivatives. PMID:17991914

  7. Observations of water vapor by ground-based micro-wave radiometers and Raman lidar

    NASA Astrophysics Data System (ADS)

    Han, Yong; Snider, J. B.; Westwater, E. R.; Melfi, S. H.; Ferrare, R. A.

    1994-09-01

    In November to December 1991, a substantial number of remote sensors and in situ instruments were operated together in Coffeyville, Kansas, during the climate experiment FIRE II. Included in the suite of instruments were (1) the NOAA Environmental Technology Laboratory (ETL) three-channel microwave radiometer, (2) the NASA GSFC Raman lidar, (3) ETL radio acoustic sounding system (RASS), and (4) frequent, research-quality radiosondes. The Raman lidar operated only at night and the focus of this portion of the experiment concentrated on clear conditions. The lidar data, together with frequent radiosondes and measurements of temperature profiles (every 15 min) by RASS allowed profiles of temperature and absolute humidity to be estimated every minute. We compared 2-min measurements of brightness temperature (Tb) with calculations of Tb that were based on the Liebe and Lay ton (1987) and Liebe et al. (1993) microwave propagation models, as well as the Waters (1976) model. The comparisons showed the best agreement at 20.6 GHz with the Waters model, with the Liebe et al. (1993) model being best at 31.65 GHz. The results at 90 GHz gave about equal success with the Liebe and Layton (1987) and Liebe et al. (1993) models. Comparisons of precipitable water vapor derived independently from the two instruments also showed excellent agreement, even for averages as short as 2 min. The rms difference between Raman and radiometric determinations of precipitable water vapor was 0.03 cm which is roughly 2%. The experiments clearly demonstrate the potential of simultaneous operation of radiometers and Raman lidars for fundamental physical studies of water vapor.

  8. Vapor bubble generation around gold nano-particles and its application to damaging of cells.

    PubMed

    Kitz, M; Preisser, S; Wetterwald, A; Jaeger, M; Thalmann, G N; Frenz, M

    2011-01-01

    We investigated vapor bubbles generated upon irradiation of gold nanoparticles with nanosecond laser pulses. Bubble formation was studied both with optical and acoustic means on supported single gold nanoparticles and single nanoparticles in suspension. Formation thresholds determined at different wavelengths indicate a bubble formation efficiency increasing with the irradiation wavelength. Vapor bubble generation in Bac-1 cells containing accumulations of the same particles was also investigated at different wavelengths. Similarly, they showed an increasing cell damage efficiency for longer wavelengths. Vapor bubbles generated by single laser pulses were about half the cell size when inducing acute damage. PMID:21339875

  9. Micro/nano-fabrication technologies for cell biology

    PubMed Central

    Qian, Tongcheng

    2012-01-01

    Micro/nano-fabrication techniques, such as soft lithography and electrospinning, have been well-developed and widely applied in many research fields in the past decade. Due to the low costs and simple procedures, these techniques have become important and popular for biological studies. In this review, we focus on the studies integrating micro/nano-fabrication work to elucidate the molecular mechanism of signaling transduction in cell biology. We first describe different micro/nano-fabrication technologies, including techniques generating three-dimensional scaffolds for tissue engineering. We then introduce the application of these technologies in manipulating the physical or chemical micro/nano-environment to regulate the cellular behavior and response, such as cell life and death, differentiation, proliferation, and cell migration. Recent advancement in integrating the micro/nano-technologies and live cell imaging are also discussed. Finally, potential schemes in cell biology involving micro/nano-fabrication technologies are proposed to provide perspectives on the future research activities. PMID:20490938

  10. A thermally self-sustained micro-power plant with integrated micro-solid oxide fuel cells, micro-reformer and functional micro-fluidic carrier

    NASA Astrophysics Data System (ADS)

    Scherrer, Barbara; Evans, Anna; Santis-Alvarez, Alejandro J.; Jiang, Bo; Martynczuk, Julia; Galinski, Henning; Nabavi, Majid; Prestat, Michel; Tölke, René; Bieberle-Hütter, Anja; Poulikakos, Dimos; Muralt, Paul; Niedermann, Philippe; Dommann, Alex; Maeder, Thomas; Heeb, Peter; Straessle, Valentin; Muller, Claude; Gauckler, Ludwig J.

    2014-07-01

    Low temperature micro-solid oxide fuel cell (micro-SOFC) systems are an attractive alternative power source for small-size portable electronic devices due to their high energy efficiency and density. Here, we report on a thermally self-sustainable reformer-micro-SOFC assembly. The device consists of a micro-reformer bonded to a silicon chip containing 30 micro-SOFC membranes and a functional glass carrier with gas channels and screen-printed heaters for start-up. Thermal independence of the device from the externally powered heater is achieved by exothermic reforming reactions above 470 °C. The reforming reaction and the fuel gas flow rate of the n-butane/air gas mixture controls the operation temperature and gas composition on the micro-SOFC membrane. In the temperature range between 505 °C and 570 °C, the gas composition after the micro-reformer consists of 12 vol.% to 28 vol.% H2. An open-circuit voltage of 1.0 V and maximum power density of 47 mW cm-2 at 565 °C is achieved with the on-chip produced hydrogen at the micro-SOFC membranes.

  11. Crystalline silicon solar cells with micro/nano texture

    NASA Astrophysics Data System (ADS)

    Dimitrov, Dimitre Z.; Du, Chen-Hsun

    2013-02-01

    Crystalline silicon solar cells with two-scale texture consisting of random upright pyramids and surface nanotextured layer directly onto the pyramids are prepared and reflectance properties and I-V characteristics measured. Random pyramids texture is produced by etching in an alkaline solution. On top of the pyramids texture, a nanotexture is developed using an electroless oxidation/etching process. Solar cells with two-scale surface texturization are prepared following the standard screen-printing technology sequence. The micro/nano surface is found to lower considerably the light reflectance of silicon. The short wavelengths spectral response (blue response) improvement is observed in micro/nano textured solar cells compared to standard upright pyramids textured cells. An efficiency of 17.5% is measured for the best micro/nano textured c-Si solar cell. The efficiency improvement is found to be due to the gain in both Jsc and Voc.

  12. Methods to Characterize Vapor Cell Performance for Nuclear Magnetic Resonance Applications

    NASA Astrophysics Data System (ADS)

    Mirijanian, James; Larsen, Michael

    2012-06-01

    The Advanced Sensors Development team at Northrop Grumman, Navigation Systems Division is developing a Nuclear Magnetic Resonance Gyroscope (NMRG). Various methods to measure atomic spin lifetimes in vapor cells for predicting NMRG performance have been investigated. Certain methods show clear advantages over others by reducing required testing times and improving test data resolution. New modifications of methods were also developed to study and improve the precision and repeatability of test results. These methods help correlate vapor cell performance to cell filling and sealing methods for cell fabrication process improvement. The vapor cells produced in conjunction with these techniques have exhibited significant and consistent increases in both the noble gas spin lifetimes and the NMR signal strengths compared to previous cell fabrication processes, providing more precise insight into cell development techniques.

  13. Micro-crack formation in direct methanol fuel cell electrodes

    NASA Astrophysics Data System (ADS)

    Li, Qing; Spernjak, Dusan; Zelenay, Piotr; Kim, Yu Seung

    2014-12-01

    This study focuses on the micro-crack formation of Nafion®-based membrane electrode assemblies (MEAs) after extended direct methanol fuel cell (DMFC) operation. All electrodes, both with metal-black and carbon-supported catalysts, contain some micro-cracks initially; the area covered by these cracks increases both in the anode and cathode after 100-hours of DMFC test. X-ray tomography shows an increase in the crack area in both anode and cathode that correlates with methanol feed concentration and methanol crossover. The MEAs with carbon-supported catalysts and thicker membrane are more resistant to the formation of micro-cracks compared to those with metal-black catalysts and thinner membrane, respectively. The impact of the micro-crack formation on cell performance and durability is limited over the 100-hour DMFC operation, with the long-term impact remaining unknown.

  14. Infrared micro-spectroscopic studies of epithelial cells

    PubMed Central

    Romeo, Melissa; Mohlenhoff, Brian; Jennings, Michael; Diem, Max

    2009-01-01

    We report results from a study of human and canine mucosal cells, investigated by infrared micro-spectroscopy, and analyzed by methods of multivariate statistics. We demonstrate that the infrared spectra of individual cells are sensitive to the stage of maturation, and that a distinction between healthy and diseased cells will be possible. Since this report is written for an audience not familiar with infrared micro-spectroscopy, a short introduction into this field is presented along with a summary of principal component analysis. PMID:16797481

  15. Vapor-deposited platinum as a fuel-cell catalyst

    NASA Technical Reports Server (NTRS)

    Asher, W. J.; Batzold, J. S.

    1974-01-01

    Electrodes are prepared by vacuum deposition of platinum on nickel substrate with conventional vapor-deposition apparatus. Amount of platinum loaded on substrate can be veried by changing exposure time during deposition. These electrodes are significantly more effective than conventional oxygen electrodes.

  16. Micro-tubular flame-assisted fuel cells for micro-combined heat and power systems

    NASA Astrophysics Data System (ADS)

    Milcarek, Ryan J.; Wang, Kang; Falkenstein-Smith, Ryan L.; Ahn, Jeongmin

    2016-02-01

    Currently the role of fuel cells in future power generation is being examined, tested and discussed. However, implementing systems is more difficult because of sealing challenges, slow start-up and complex thermal management and fuel processing. A novel furnace system with a flame-assisted fuel cell is proposed that combines the thermal management and fuel processing systems by utilizing fuel-rich combustion. In addition, the flame-assisted fuel cell furnace is a micro-combined heat and power system, which can produce electricity for homes or businesses, providing resilience during power disruption while still providing heat. A micro-tubular solid oxide fuel cell achieves a significant performance of 430 mW cm-2 operating in a model fuel-rich exhaust stream.

  17. Passive cathodic water/air management device for micro-direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Peng, Hsien-Chih; Chen, Po-Hon; Chen, Hung-Wen; Chieng, Ching-Chang; Yeh, Tsung-Kuang; Pan, Chin; Tseng, Fan-Gang

    A high efficient passive water/air management device (WAMD) is proposed and successfully demonstrated in this paper. The apparatus consists of cornered micro-channels and air-breathing windows with hydrophobicity arrangement to regulate liquids and gases to flow on their predetermined pathways. A high performance water/air separation with water removal rate of about 5.1 μl s -1 cm -2 is demonstrated. The performance of the proposed WAMD is sufficient to manage a cathode-generated water flux of 0.26 μl s -1 cm -2 in the micro-direct methanol fuel cells (μDMFCs) which are operated at 100 mW cm -2 or 400 mA cm -2. Furthermore, the condensed vapors can also be collected and recirculated with the existing micro-channels which act as a passive water recycling system for μDMFCs. The durability testing shows that the fuel cells equipped with WAMD exhibit improved stability and higher current density.

  18. Progress toward cascade cells made by OM-VPE. [organometallic vapor phase epitaxy

    NASA Technical Reports Server (NTRS)

    Borden, P. G.; Larue, R. A.; Ludowise, M. J.

    1982-01-01

    Organometallic Vapor Phase Epitaxy (COM-VPE) was used to make a sophisticated monolithic cascade cell, with a peak AMO efficiency of 16.6%, not corrected for 14% grid coverage. The cell has 9 epitaxial layers. The top cell is 1.35 microns thick with a 0.1 micron thich emitter. Both cells are heteroface n-p structures. The cascade cell uses metal interconnects. Details of growth and processing are described.

  19. Aging studies on micro-fabricated alkali buffer-gas cells for miniature atomic clocks

    SciTech Connect

    Abdullah, S.; Affolderbach, C.; Gruet, F.; Mileti, G.

    2015-04-20

    We report an aging study on micro-fabricated alkali vapor cells using neon as a buffer gas. An experimental atomic clock setup is used to measure the cell's intrinsic frequency, by recording the clock frequency shift at different light intensities and extrapolating to zero intensity. We find a drift of the cell's intrinsic frequency of (−5.2 ± 0.6) × 10{sup −11}/day and quantify deterministic variations in sources of clock frequency shifts due to the major physical effects to identify the most probable cause of the drift. The measured drift is one order of magnitude stronger than the total frequency variations expected from clock parameter variations and corresponds to a slow reduction of buffer gas pressure inside the cell, which is compatible with the hypothesis of loss of Ne gas from the cell due to its permeation through the cell windows. A negative drift on the intrinsic cell frequency is reproducible for another cell of the same type. Based on the Ne permeation model and the measured cell frequency drift, we determine the permeation constant of Ne through borosilicate glass as (5.7 ± 0.7) × 10{sup −22} m{sup 2} s{sup −1 }Pa{sup −1} at 81 °C. We propose this method based on frequency metrology in an alkali vapor cell atomic clock setup based on coherent population trapping for measuring permeation constants of inert gases.

  20. Regulation of Vapor Pressure Deficit by Greenhouse Micro-Fog Systems Improved Growth and Productivity of Tomato via Enhancing Photosynthesis during Summer Season.

    PubMed

    Zhang, Dalong; Zhang, Zhongdian; Li, Jianming; Chang, Yibo; Du, Qingjie; Pan, Tonghua

    2015-01-01

    The role of a proposed micro-fog system in regulating greenhouse environments and enhancing tomato (Solanum lycopersicum L.) productivity during summer season was studied. Experiments were carried out in a multi-span glass greenhouse, which was divided into two identical compartments involving different environments: (1) without environment control and (2) with a micro-fog system operating when the air vapor pressure deficit (VPD) of greenhouse was higher than 0.5 KPa. The micro-fog system effectively alleviated heat stress and evaporative demand in the greenhouse during summer season. The physiologically favourable environment maintained by micro-fog treatment significantly enhanced elongation of leaf and stem, which contributed to a substantial elevation of final leaf area and shoot biomass. These improvements in physiological and morphological traits resulted in around 12.3% increase of marketable tomato yield per plant. Relative growth rate (RGR) of micro-fog treatment was also significantly higher than control plants, which was mainly determined by the substantial elevation in net assimilation rate (NAR), and to a lesser extent caused by leaf area ratio (LAR). Measurement of leaf gas exchange parameters also demonstrated that micro-fog treatment significantly enhanced leaf photosynthesis capacity. Taken together, manipulation of VPD in greenhouses by micro-fog systems effectively enhanced tomato growth and productivity via improving photosynthesis during summer season. PMID:26221726

  1. Regulation of Vapor Pressure Deficit by Greenhouse Micro-Fog Systems Improved Growth and Productivity of Tomato via Enhancing Photosynthesis during Summer Season

    PubMed Central

    Zhang, Dalong; Zhang, Zhongdian; Li, Jianming; Chang, Yibo; Du, Qingjie; Pan, Tonghua

    2015-01-01

    The role of a proposed micro-fog system in regulating greenhouse environments and enhancing tomato (Solanum lycopersicum L.) productivity during summer season was studied. Experiments were carried out in a multi-span glass greenhouse, which was divided into two identical compartments involving different environments: (1) without environment control and (2) with a micro-fog system operating when the air vapor pressure deficit (VPD) of greenhouse was higher than 0.5 KPa. The micro-fog system effectively alleviated heat stress and evaporative demand in the greenhouse during summer season. The physiologically favourable environment maintained by micro-fog treatment significantly enhanced elongation of leaf and stem, which contributed to a substantial elevation of final leaf area and shoot biomass. These improvements in physiological and morphological traits resulted in around 12.3% increase of marketable tomato yield per plant. Relative growth rate (RGR) of micro-fog treatment was also significantly higher than control plants, which was mainly determined by the substantial elevation in net assimilation rate (NAR), and to a lesser extent caused by leaf area ratio (LAR). Measurement of leaf gas exchange parameters also demonstrated that micro-fog treatment significantly enhanced leaf photosynthesis capacity. Taken together, manipulation of VPD in greenhouses by micro-fog systems effectively enhanced tomato growth and productivity via improving photosynthesis during summer season. PMID:26221726

  2. The Role of microRNAs in Animal Cell Reprogramming.

    PubMed

    Cruz-Santos, María Concepción; Aragón-Raygoza, Alejandro; Espinal-Centeno, Annie; Arteaga-Vázquez, Mario; Cruz-Hernández, Andrés; Bako, Laszlo; Cruz-Ramírez, Alfredo

    2016-07-15

    Our concept of cell reprogramming and cell plasticity has evolved since John Gurdon transferred the nucleus of a completely differentiated cell into an enucleated Xenopus laevis egg, thereby generating embryos that developed into tadpoles. More recently, induced expression of transcription factors, oct4, sox2, klf4, and c-myc has evidenced the plasticity of the genome to change the expression program and cell phenotype by driving differentiated cells to the pluripotent state. Beyond these milestone achievements, research in artificial cell reprogramming has been focused on other molecules that are different than transcription factors. Among the candidate molecules, microRNAs (miRNAs) stand out due to their potential to control the levels of proteins that are involved in cellular processes such as self-renewal, proliferation, and differentiation. Here, we review the role of miRNAs in the maintenance and differentiation of mesenchymal stem cells, epimorphic regeneration, and somatic cell reprogramming to induced pluripotent stem cells. PMID:27224014

  3. Cell Membranes Under Hydrostatic Pressure Subjected to Micro-Injection

    NASA Astrophysics Data System (ADS)

    Vassilev, Vassil M.; Kostadinov, Kostadin G.; Mladenov, Ivaïlo M.; Shulev, Assen A.; Stoilov, Georgi I.; Djondjorov, Peter A.

    2011-04-01

    The work is concerned with the determination of the mechanical behaviour of cell membranes under uniform hydrostatic pressure subject to micro-injections. For that purpose, assuming that the shape of the deformed cell membrane is axisymmetric a variational statement of the problem is developed on the ground of the so-called spontaneous curvature model. In this setting, the cell membrane is regarded as an axisymmetric surface in the three-dimensional Euclidean space providing a stationary value of the shape energy functional under the constraint of fixed total area and fixed enclosed volume. The corresponding Euler-Lagrange equations and natural boundary conditions are derived, analyzed and used to express the forces and moments in the membrane. Several examples of such surfaces representing possible shapes of cell membranes under pressure subjected to micro injection are determined numerically.

  4. Ultrashort laser pulse cell manipulation using nano- and micro- materials

    NASA Astrophysics Data System (ADS)

    Schomaker, Markus; Killian, Doreen; Willenbrock, Saskia; Diebold, Eric; Mazur, Eric; Bintig, Willem; Ngezahayo, Anaclet; Nolte, Ingo; Murua Escobar, Hugo; Junghanß, Christian; Lubatschowski, Holger; Heisterkamp, Alexander

    2010-08-01

    The delivery of extra cellular molecules into cells is essential for cell manipulation. For this purpose genetic materials (DNA/RNA) or proteins have to overcome the impermeable cell membrane. To increase the delivery efficiency and cell viability of common methods different nano- and micro material based approaches were applied. To manipulate the cells, the membrane is in contact with the biocompatible material. Due to a field enhancement of the laser light at the material and the resulting effect the cell membrane gets perforated and extracellular molecules can diffuse into the cytoplasm. Membrane impermeable dyes, fluorescent labelled siRNA, as well as plasmid vectors encoded for GFP expression were used as an indicator for successful perforation or transfection, respectively. Dependent on the used material, perforation efficiencies over 90 % with a cell viability of about 80 % can be achieved. Additionally, we observed similar efficiencies for siRNA transfection. Due to the larger molecule size and the essential transport of the DNA into the nucleus cells are more difficult to transfect with GFP plasmid vectors. Proof of principle experiments show promising and adequate efficiencies by applying micro materials for plasmid vector transfection. For all methods a weakly focused fs laser beam is used to enable a high manipulation throughput for adherent and suspension cells. Furthermore, with these alternative optical manipulation methods it is possible to perforate the membrane of sensitive cell types such as primary and stem cells with a high viability.

  5. Alkali-vapor cell with metal coated windows for efficient application of an electric field

    NASA Astrophysics Data System (ADS)

    Sarkisyan, D.; Sarkisyan, A. S.; Guéna, J.; Lintz, M.; Bouchiat, M.-A.

    2005-05-01

    We describe the implementation of a cylindrical T-shaped alkali-vapor cell for laser spectroscopy in the presence of a longitudinal electric field. The two windows are used as two electrodes of the high-voltage assembly, which is made possible by a metallic coating which entirely covers the inner and outer sides of the windows except for a central area to let the laser beams in and out of the cell. This allows very efficient application of the electric field, up to 2kV/cm in a rather dense superheated vapor, even when significant photoemission takes place at the windows during pulsed laser irradiation. The body of the cell is made of sapphire or alumina ceramic to prevent large currents resulting from surface conduction observed in cesiated glass cells. The technique used to attach the monocrystalline sapphire windows to the cell body causes minimal stress birefringence in the windows. In addition, reflection losses at the windows can be made very small. The vapor cell operates with no buffer gas and has no magnetic part. The use of this kind of cell has resulted in an improvement of the signal-to-noise ratio in the measurement of parity violation in cesium vapor underway at ENS, Paris. The technique can be applied to other situations where a brazed assembly would give rise to unacceptably large birefringence in the windows.

  6. Spin-polarized lithium diffusion in a glass hot-vapor cell

    NASA Astrophysics Data System (ADS)

    Ishikawa, Kiyoshi

    2016-08-01

    We report diffusion coefficients of optically pumped lithium atoms in helium buffer gas. The free-induction decay and the spin-echo signals of ground-state atoms were optically detected in an external magnetic field with the addition of field gradient. Lithium hot vapor was produced in a borosilicate-glass cell at a temperature between 290 and 360°C. The simple setup using the glass cells enabled lithium atomic spectroscopy in a similar way to other alkali-metal atoms and study of the collisional properties of lithium atoms in a hot-vapor phase.

  7. MicroRNAs and cell cycle of malignant glioma.

    PubMed

    Ouyang, Qing; Xu, Lunshan; Cui, Hongjuan; Xu, Minhui; Yi, Liang

    2016-01-01

    The control of malignant glioma cell cycle by microRNAs (miRNAs) is well established. The deregulation of miRNAs in glioma may contribute to tumor proliferation by directly targeting the critical cell-cycle regulators. Tumor suppressive miRNAs inhibit cell cycle through repressing the expression of positive cell-cycle regulators. However, oncogenic miRNAs promote the cell-cycle progression by targeting cell-cycle negative regulators. Recent studies have identified that transcription factors had involved in the expression of miRNAs. Transcription factors and miRNAs are implicated in regulatory network of glioma cell cycle, the deregulation of these transcription factors might be a cause of the deregulation of miRNAs. Abnormal versions of miRNAs have been implicated in the cell cycle of glioma. Based on those, miRNAs are excellent biomarker candidates and potential targets for therapeutic intervention in glioma. PMID:26000816

  8. Characterization of antirelaxation-coated vapor cells in high-temperature regime

    NASA Astrophysics Data System (ADS)

    Li, Wenhao; Balabas, Mikhail; Pustelny, Szymon; Wickenbrock, Arne; Budker, Dmitry

    2016-05-01

    Antirelaxation-coated vapor cells are widely used in modern atomic physics experiments due to the coating's ability to maintain spin polarization during wall collisions. We characterize the performance of vapor cells with different coating materials by measuring longitudinal spin relaxation and vapor density at temperatures of up to 90° C. The longitudinal spin relaxation time (τrel) is measured with a modified version of ``relaxation in the dark'' technique and the vapor density (n) is obtained by fitting atomic absorption spectrum with linear absorption function. The spin-projection-noise-limited (or atomic shot noise limited) sensitivity for atomic magnetometers is δBSNL 1 /√{ nτrel T } , where T is measurement time. Therefore, by showing the product of the longitudinal spin relaxation time and the vapor density increases with temperature, we demonstrate the potential of antirelaxation-coated cells in applications of future high-sensitivity magnetometers. W.L. would like to acknowledge support from the China Scholarship Council (CSC) enabling his research at the University of California at Berkeley.

  9. Intrinsic Impurities in Glass Alkali-Vapor Cells

    NASA Astrophysics Data System (ADS)

    Patton, B.; Ishikawa, K.; Jau, Y.-Y.; Happer, W.

    2007-07-01

    We report NMR measurements of metallic Cs133 in glass cells. The solid-liquid phase transition was studied by observing the NMR peaks arising from these two phases; surprisingly, many cells yielded two additional NMR peaks below the melting point. We attribute these signals to two distinct impurities which can dissolve in the liquid alkali metal and affect its chemical shift. Intentional contamination of cesium cells with O2 confirms this hypothesis for one peak. The other contaminant remains unknown but can appear in evacuated cells. Similar effects have been seen in Rb87 cells.

  10. Dispersive radio frequency electrometry using Rydberg atoms in a prism-shaped atomic vapor cell

    NASA Astrophysics Data System (ADS)

    Fan, H. Q.; Kumar, S.; Kübler, H.; Shaffer, J. P.

    2016-05-01

    We introduce a method to measure radio frequency (RF) electric fields (E-fields) using atoms contained in a prism-shaped vapor cell. The method utilizes the concept of electromagnetically induced transparency with Rydberg atoms. The RF E-field induces changes in the index of refraction of the vapor resulting in deflection of the probe laser beam as it passes through the prism-shaped vapor cell. We measured a minimum RF E-field of 8.25 μ {{Vcm}}-1 with a sensitivity of ∼ 46.5 μ {{Vcm}}-1 {{Hz}}-1/2. The experimental results agree with a numerical model that includes dephasing effects. We discuss possible improvements to obtain higher sensitivity for RF E-field measurements.

  11. Coherent population trapping in small- and chip-scale 87Rb vapor cells with buffer gas

    NASA Astrophysics Data System (ADS)

    Ermak, S. V.; Semenov, V. V.; Petrenko, M. V.; Pyatyshev, E. N.

    2016-03-01

    The characteristics of coherent population trapping (CPT) signal were investigated in small-size glass vapor cells containing 87Rb and Ne buffer gas with narrow line-width laser pumping on D2 line. The parameters of CPT signals were measured using small-size vapor cells with Ne buffer gas pressure in the range of 200-400 Torr, cell temperature in the range of 65-120 ∘C and the values of laser pumping power of 30-400 μW/cm2. Optimal conditions, under which the minimal value of short-term instability of resonance line is achieved, were obtained in experiments. Orientation frequency shifts of CPT resonance using glass 87Rb vapor cells containing buffer gas and anti-relaxation coating were compared. CPT signals using vapor cells based on integrated technologies containing 87Rb in atmosphere of Ne were also investigated. The CPT signals with typical line widths of 2-3 kHz and signal-to-noise ratio of 1500 in 1 Hz bandwidth are observed, which allows one to provide relative frequency instability of 10-11 at 100 s.

  12. Speciated fine-particle (<2.5 {micro}m aerodynamic diameter) and vapor-phase acid concentrations in southern California

    SciTech Connect

    Taylor, C.A. Jr.; Stover, C.A.; Westerdahl, F.D.

    1998-12-31

    A fine-particle (<2.5 {micro}m aerodynamic diameter) and vapor-phase acid sampling network has been in operation among 12 communities in southern California since late 1993. The data from this network consists of concentrations of particulate matter <10 {micro}m in aerodynamic diameter (PM10), nitrogen dioxide, ozone, vapor-phase hydrochloric, nitric, acetic, and formic acids, particulate matter <2.5 {micro}m in aerodynamic diameter (PM2.5), and the chloride, nitrate, sulfate, and ammonium components of PM2.5. These measurements are the basis of the exposure assessment estimates of the Children`s Health Study, a multi-year study, mainly of lung function development and respiratory illness, taking place in southern California. One of the goals of the Children`s Health Study is to utilize a cost-effective means of obtaining continuous fine-particle and vapor-phase acid data for a multi-year study with enough time resolution to allow seasonal estimates of exposure. A two-week sampler was developed to meet these needs. Four continuous years of vapor-phase acid and PM2.5 mass, chloride, nitrate, sulfate, and ammonium data have been collected. During this time, the sampler has proven to be reliable. A decline in PM2.5 mass, nitrate, and ammonium ions in most of the communities from 1994 to 1997 was observed. In contrast, very little change in vapor-phase acids was observed. There has been increased interest at the national level in fine particles and their characteristics. The network provides a rich database that can be used to characterize southern California communities on the basis of their level of fine particles (and their components) and vapor-phase acids and should prove valuable with respect to both prospective and retrospective health studies. The database also provides a general characterization of the levels of PM2.5 affecting 25 million people in southern California.

  13. A Micro Fluorescent Activated Cell Sorter for Astrobiology Applications

    NASA Technical Reports Server (NTRS)

    Platt, Donald W.; Hoover, Richard B.

    2009-01-01

    A micro-scale Fluorescent Activated Cell Sorter (microFACS) for astrobiology applications is under development. This device is designed to have a footprint of 7 cm x 7 cm x 4 cm and allow live-dead counts and sorting of cells that have fluorescent characteristics from staining. The FACS system takes advantage of microfluidics to create a cell sorter that can fit in the palm of the hand. A micron-scale channel allows cells to pass by a blue diode which causes emission of marker-expressed cells which are detected by a filtered photodetector. A small microcontroller then counts cells and operates high speed valves to select which chamber the cell is collected in (a collection chamber or a waste chamber). Cells with the expressed characteristic will be collected in the collection chamber. This system has been built and is currently being tested. We are also designing a system with integrated MEMS-based pumps and valves for a small and compact unit to fly on small satellite-based biology experiments.

  14. Stem cells and germ cells: microRNA and gene expression signatures.

    PubMed

    Dyce, Paul William; Toms, Derek; Li, Julang

    2010-04-01

    The study of primordial germ cell development in vivo is hampered by their low numbers and inaccessibility. Recent research has shown the ability of embryonic and adult stem cells to differentiate into primordial germ cells and more mature gametes and this generation of germ cells in vitro may be an attractive model for their study. One of the biggest challenges facing in vitro differentiation of stem cells into primordial germ cells is the lack of markers to clearly distinguish the two. As both cell types originate early in embryonic development they share many pluripotent markers such as OCT4, VASA, FRAGILIS, and NANOG. Genome wide microarray profiling has been used to identify transcriptome patterns unique to primordial germ cells. A more thorough analysis of the temporal and quantitative expression of a panel of genes may be more robust in distinguishing these two cell populations. MicroRNAs, short RNA molecules that have been shown to regulate translation through interactions with mRNA transcripts, have also recently come under investigation for the role they may play in pluripotency. Attempts to elucidate key microRNAs responsible for both stem cell and primordial germ cell characteristics have recently been undertaken. Unique microRNAs, either individually or as global profiles, may also help to distinguish differentiated primordial germ cells from stem cells in vitro. This review will examine gene expression and microRNA signatures in stem cells and germ cells as ways to distinguish these closely related cell types. PMID:20183803

  15. The functionalization of nanodiamonds (diamondoids) as a key parameter of their easily controlled self-assembly in micro- and nanocrystals from the vapor phase

    NASA Astrophysics Data System (ADS)

    Gunawan, Maria A.; Poinsot, Didier; Domenichini, Bruno; Dirand, Céline; Chevalier, Sébastien; Fokin, Andrey A.; Schreiner, Peter R.; Hierso, Jean-Cyrille

    2015-01-01

    We detail herein readily accessible processes to control previously unobserved robust self-assemblies of nanodiamonds (diamondoids) in micro- and nanocrystals from their mild vapor deposition. The chemical functionalization of uniform and discernible nanodiamonds was found to be a key parameter, and depending on the type of functional group (hydroxy, fluorine, etc.) and its position on the diamondoid, the structure of the discrete deposits can vary dramatically. Thus, well-defined anisotropic structures such as rod, needle, triangle or truncated octahedron shapes can be obtained, and self-assembled edifices of sizes ranging from 20 nm to several hundred micrometers formed with conservation of a similar structure for a given diamondoid. Key thermodynamic data including sublimation enthalpy of diamondoid derivatives are reported, and the SEM of the self-assemblies coupled with EDX analyses and XRD attest the nature and purity of nanodiamond crystal deposits. This attractive method is simple and outperforms in terms of deposit quality dip-coating methods we used. This vapor phase deposition approach is expected to allow for an easy formation of diamondoid nanoobjects on different types of substrates.We detail herein readily accessible processes to control previously unobserved robust self-assemblies of nanodiamonds (diamondoids) in micro- and nanocrystals from their mild vapor deposition. The chemical functionalization of uniform and discernible nanodiamonds was found to be a key parameter, and depending on the type of functional group (hydroxy, fluorine, etc.) and its position on the diamondoid, the structure of the discrete deposits can vary dramatically. Thus, well-defined anisotropic structures such as rod, needle, triangle or truncated octahedron shapes can be obtained, and self-assembled edifices of sizes ranging from 20 nm to several hundred micrometers formed with conservation of a similar structure for a given diamondoid. Key thermodynamic data including

  16. MicroRNAs: From Female Fertility, Germ Cells, and Stem Cells to Cancer in Humans

    PubMed Central

    Virant-Klun, Irma; Ståhlberg, Anders; Kubista, Mikael; Skutella, Thomas

    2016-01-01

    MicroRNAs are a family of naturally occurring small noncoding RNA molecules that play an important regulatory role in gene expression. They are suggested to regulate a large proportion of protein encoding genes by mediating the translational suppression and posttranscriptional control of gene expression. Recent findings show that microRNAs are emerging as important regulators of cellular differentiation and dedifferentiation, and are deeply involved in developmental processes including human preimplantation development. They keep a balance between pluripotency and differentiation in the embryo and embryonic stem cells. Moreover, it became evident that dysregulation of microRNA expression may play a fundamental role in progression and dissemination of different cancers including ovarian cancer. The interest is still increased by the discovery of exosomes, that is, cell-derived vesicles, which can carry different proteins but also microRNAs between different cells and are involved in cell-to-cell communication. MicroRNAs, together with exosomes, have a great potential to be used for prognosis, therapy, and biomarkers of different diseases including infertility. The aim of this review paper is to summarize the existent knowledge on microRNAs related to female fertility and cancer: from primordial germ cells and ovarian function, germinal stem cells, oocytes, and embryos to embryonic stem cells. PMID:26664407

  17. Imaging of relaxation times and microwave field strength in a microfabricated vapor cell

    NASA Astrophysics Data System (ADS)

    Horsley, Andrew; Du, Guan-Xiang; Pellaton, Matthieu; Affolderbach, Christoph; Mileti, Gaetano; Treutlein, Philipp

    2013-12-01

    We present a characterization technique for atomic vapor cells, combining time-domain measurements with absorption imaging to obtain spatially resolved information on decay times, atomic diffusion, and coherent dynamics. The technique is used to characterize a 5-mm-diameter, 2-mm-thick microfabricated Rb vapor cell, with N2 buffer gas, placed inside a microwave cavity. Time-domain Franzen and Ramsey measurements are used to produce high-resolution images of the population (T1) and coherence (T2) lifetimes in the cell, while Rabi measurements yield images of the σ-, π, and σ+ components of the applied microwave magnetic field. For a cell temperature of 90∘C, the T1 times across the cell center are found to be a roughly uniform 265μs, while the T2 times peak at around 350μs. We observe a “skin” of reduced T1 and T2 times around the edge of the cell due to the depolarization of Rb after collisions with the silicon cell walls. Our observations suggest that these collisions are far from being 100% depolarizing, consistent with earlier observations made with Na and glass walls. Images of the microwave magnetic field reveal regions of optimal field homogeneity, and thus coherence. Our technique is useful for vapor cell characterization in atomic clocks, atomic sensors, and quantum information experiments.

  18. Catalyst-free direct vapor-phase growth of Zn1−xCuxO micro-cross structures and their optical properties

    PubMed Central

    2013-01-01

    We report a simple catalyst-free vapor-phase method to fabricate Zn1−xCuxO micro-cross structures. Through a series of controlled experiments by changing the location of the substrate and reaction time, we have realized the continuous evolution of product morphology from nanorods into brush-like structures and micro-cross structures at different positions, together with the epitaxial growth of branched nanorods from the central stem with the time extended. The growth mechanism of the Zn1−xCuxO micro-cross structures has been proposed to involve the synthesis of Cu/Zn square-like core, surface oxidation, and the secondary growth of nanorod arrays. By the detailed structural analysis of the yielded Zn1−xCuxO samples at different locations, we have shown that the CuO phases were gradually formed in Zn1−xCuxO, which is significant to induce the usual ZnO hexagonal structures changing into four-folded symmetrical hierarchical micro-cross structures. Furthermore, the visible luminescence can be greatly enhanced by the introduction of Cu, and the observed inhomogeneous cathode luminescence in an individual micro-cross structure is caused by the different distributions of Cu. PMID:23339397

  19. Catalyst-free direct vapor-phase growth of Zn1-xCuxO micro-cross structures and their optical properties.

    PubMed

    Xu, Danhua; Fan, Donghua; Shen, Wenzhong

    2013-01-01

    We report a simple catalyst-free vapor-phase method to fabricate Zn1-xCuxO micro-cross structures. Through a series of controlled experiments by changing the location of the substrate and reaction time, we have realized the continuous evolution of product morphology from nanorods into brush-like structures and micro-cross structures at different positions, together with the epitaxial growth of branched nanorods from the central stem with the time extended. The growth mechanism of the Zn1-xCuxO micro-cross structures has been proposed to involve the synthesis of Cu/Zn square-like core, surface oxidation, and the secondary growth of nanorod arrays. By the detailed structural analysis of the yielded Zn1-xCuxO samples at different locations, we have shown that the CuO phases were gradually formed in Zn1-xCuxO, which is significant to induce the usual ZnO hexagonal structures changing into four-folded symmetrical hierarchical micro-cross structures. Furthermore, the visible luminescence can be greatly enhanced by the introduction of Cu, and the observed inhomogeneous cathode luminescence in an individual micro-cross structure is caused by the different distributions of Cu. PMID:23339397

  20. High Pressure Chemical Vapor Deposition of Hydrogenated Amorphous Silicon Films and Solar Cells.

    PubMed

    He, Rongrui; Day, Todd D; Sparks, Justin R; Sullivan, Nichole F; Badding, John V

    2016-07-01

    Thin films of hydrogenated amorphous silicon can be produced at MPa pressures from silane without the use of plasma at temperatures as low as 345 °C. High pressure chemical vapor deposition may open a new way to low cost deposition of amorphous silicon solar cells and other thin film structures over very large areas in very compact, simple reactors. PMID:27174318

  1. All-Hot-Wire Chemical Vapor Deposition a-Si:H Solar Cells

    SciTech Connect

    Iwaniczko, E.; Wang, Q.; Xu, Y.; Nelson, B. P.; Mahan, A. H.; Crandall, R. S.; Branz, H. M.

    2000-01-01

    Efficient hydrogenated amorphous silicon (a-Si:H) nip solar cells have been fabricated with all doped and undoped a-Si:H layers deposited by hot-wire chemical vapor deposition (HWCVD). The total deposition time of all layers, except the top ITO-contact, is less than 4 minutes.

  2. Micro-magnet arrays for specific single bacterial cell positioning

    NASA Astrophysics Data System (ADS)

    Pivetal, Jérémy; Royet, David; Ciuta, Georgeta; Frenea-Robin, Marie; Haddour, Naoufel; Dempsey, Nora M.; Dumas-Bouchiat, Frédéric; Simonet, Pascal

    2015-04-01

    In various contexts such as pathogen detection or analysis of microbial diversity where cellular heterogeneity must be taken into account, there is a growing need for tools and methods that enable microbiologists to analyze bacterial cells individually. One of the main challenges in the development of new platforms for single cell studies is to perform precise cell positioning, but the ability to specifically target cells is also important in many applications. In this work, we report the development of new strategies to selectively trap single bacterial cells upon large arrays, based on the use of micro-magnets. Escherichia coli bacteria were used to demonstrate magnetically driven bacterial cell organization. In order to provide a flexible approach adaptable to several applications in the field of microbiology, cells were magnetically and specifically labeled using two different strategies, namely immunomagnetic labeling and magnetic in situ hybridization. Results show that centimeter-sized arrays of targeted, isolated bacteria can be successfully created upon the surface of a flat magnetically patterned hard magnetic film. Efforts are now being directed towards the integration of a detection tool to provide a complete micro-system device for a variety of microbiological applications.

  3. A Micro-Preconcentrator Combined Olfactory Sensing System with a Micromechanical Cantilever Sensor for Detecting 2,4-Dinitrotoluene Gas Vapor

    PubMed Central

    Chae, Myung-Sic; Kim, Jinsik; Yoo, Yong Kyoung; Kang, Ji Yoon; Lee, Jeong Hoon; Hwang, Kyo Seon

    2015-01-01

    Preventing unexpected explosive attacks and tracing explosion-related molecules require the development of highly sensitive gas-vapor detection systems. For that purpose, a micromechanical cantilever-based olfactory sensing system including a sample preconcentrator was developed to detect 2,4-dinitrotoluene (2,4-DNT), which is a well-known by-product of the explosive molecule trinitrotoluene (TNT) and exists in concentrations on the order of parts per billion in the atmosphere at room temperature. A peptide receptor (His-Pro-Asn-Phe-Ser-Lys-Tyr-Ile-Leu-His-Gln-Arg) that has high binding affinity for 2,4-DNT was immobilized on the surface of the cantilever sensors to detect 2,4-DNT vapor for highly selective detection. A micro-preconcentrator (µPC) was developed using Tenax-TA adsorbent to produce higher concentrations of 2,4-DNT molecules. The preconcentration was achieved via adsorption and thermal desorption phenomena occurring between target molecules and the adsorbent. The µPC directly integrated with a cantilever sensor and enhanced the sensitivity of the cantilever sensor as a pretreatment tool for the target vapor. The response was rapidly saturated within 5 min and sustained for more than 10 min when the concentrated vapor was introduced. By calculating preconcentration factor values, we verified that the cantilever sensor provides up to an eightfold improvement in sensing performance. PMID:26213944

  4. MicroRNAs as novel regulators of stem cell fate

    PubMed Central

    Choi, Eunhyun; Choi, Eunmi; Hwang, Ki-Chul

    2013-01-01

    Mounting evidence in stem cell biology has shown that microRNAs (miRNAs) play a crucial role in cell fate specification, including stem cell self-renewal, lineage-specific differentiation, and somatic cell reprogramming. These functions are tightly regulated by specific gene expression patterns that involve miRNAs and transcription factors. To maintain stem cell pluripotency, specific miRNAs suppress transcription factors that promote differentiation, whereas to initiate differentiation, lineage-specific miRNAs are upregulated via the inhibition of transcription factors that promote self-renewal. Small molecules can be used in a similar manner as natural miRNAs, and a number of natural and synthetic small molecules have been isolated and developed to regulate stem cell fate. Using miRNAs as novel regulators of stem cell fate will provide insight into stem cell biology and aid in understanding the molecular mechanisms and crosstalk between miRNAs and stem cells. Ultimately, advances in the regulation of stem cell fate will contribute to the development of effective medical therapies for tissue repair and regeneration. This review summarizes the current insights into stem cell fate determination by miRNAs with a focus on stem cell self-renewal, differentiation, and reprogramming. Small molecules that control stem cell fate are also highlighted. PMID:24179605

  5. Novel Integration Approach for In situ Monitoring of Temperature in Micro-direct Methanol Fuel Cell

    NASA Astrophysics Data System (ADS)

    Lee, Chi-Yuan; Huang, Ren-De; Chuang, Chih-Wei

    2007-10-01

    In this work, a porous silicon layer is fabricated as the gas diffusion layer (GDL) of a micro-direct methanol fuel cell (μDMFC) using micro-electro-mechanical-systems (MEMS) technology. Platinum is deposited on surface of the porous silicon layer to improve the electrical conductivity of the μDMFC. Physical vapor deposition (PVD) was utilized to deposit Pt metal and wet etching was adopted to form the conductive layer and micro-thermal sensors. The Pt acted both as a current collector and a micro-thermal sensor. We fabricated a resistance temperature detector (RTD) sensor for integration with the gas diffusion layer on the bipolar plate to measure the temperature inside the μDMFC. GDLs with pores of various sizes (10, 30, and 50 μm) were considered to test the performance of the μDMFC. A silicon wafer (500 μm) was etched using KOH wet etching to yield fuel channels with a depth of 450 μm and a width of 200 μm. Then, a porous silicon layer was formed by deep reactive ion etching (DRIE) to act as the GDL of the μDMFC. The experimental results obtained at various fuel flow rates, pore sizes and other operating conditions demonstrate that the maximum power density of the μDMFC is 1.784 mW/cm2, which was reached at 203 mV with 50-μm-diameter holes. The microsensor temperature was determined to be in the range from 20 to 46 °C and the resistance of the microsensor was in the range from 7.524 to 7.677 kΩ. Experimental results demonstrate that temperature is almost linearly related to resistance and that accuracy and sensitivity are 0.3 °C and 7.82× 10-4/°C, respectively.

  6. Modification of glass cell walls by rubidium vapor

    NASA Astrophysics Data System (ADS)

    Ma, J.; Kishinevski, A.; Jau, Y.-Y.; Reuter, C.; Happer, W.

    2009-04-01

    It has long been known that the inner walls of freshly manufactured glass cells filled with a few droplets of alkali metal undergo a “curing” process, where the properties of the cell wall change over a period of days to weeks. We report quantitative studies of “curing” in Pyrex cells filled with rubidium metal. Our experiment shows that at 94°C , the surface of Pyrex glass adsorbs about 3×1015 rubidium atoms per cm2 , which is equivalent to 6-7 monolayers of liquid rubidium.

  7. Laser pulse propagation in a meter scale rubidium vapor/plasma cell in AWAKE experiment

    NASA Astrophysics Data System (ADS)

    Joulaei, A.; Moody, J.; Berti, N.; Kasparian, J.; Mirzanejhad, S.; Muggli, P.

    2016-09-01

    We present the results of numerical studies of laser pulse propagating in a 3.5 cm Rb vapor cell in the linear dispersion regime by using a 1D model and a 2D code that has been modified for our special case. The 2D simulation finally aimed at finding laser beam parameters suitable to make the Rb vapor fully ionized to obtain a uniform, 10 m-long, at least 1 mm in radius plasma in the next step for the AWAKE experiment.

  8. Novel duplex vapor-electrochemical method for silicon solar cells

    NASA Technical Reports Server (NTRS)

    Nanis, L.; Sanjurjo, A.; Sancier, K. M.; Kapur, V. K.; Bartlett, R. W.; Westphal, S.

    1980-01-01

    A process was developed for the economic production of high purity Si from inexpensive reactants, based on the Na reduction of SiF4 gas. The products of reaction (NaF, Si) are separated by either aqueous leaching or by direct melting of the NaF-Si product mixture. Impurities known to degrade solar cell performance are all present at sufficiently low concentrations so that melt solidification (e.g., Czochralski) will provide a silicon material suitable for solar cells.

  9. Oxidative Chemical Vapor Deposition of Neutral Hole Transporting Polymer for Enhanced Solar Cell Efficiency and Lifetime.

    PubMed

    Jo, Won Jun; Nelson, Justin T; Chang, Sehoon; Bulović, Vladimir; Gradečak, Silvija; Strano, Michael S; Gleason, Karen K

    2016-08-01

    The concept of a neutral hole-transporting polymer is realized for the first time, by integrating patterned Cl(-) -doped poly(3,4-dimethoxythiophene) thin films into organic solar cells through a vacuum-based polymer vapor printing technique. Due to this novel polymer's neutrality, high transparency, good conductivity, and appropriate energy levels, the solar-cell efficiency and lifetime are significantly enhanced. PMID:27167214

  10. MICRO- AND NANOSCALE ENGINEERING OF CELL SIGNALING”

    PubMed Central

    Kam, L.C.; Shen, K.; Dustin, M.L.

    2014-01-01

    It is increasing recognized that cell signaling, as a chemical process, must be considered at the local, micrometer scale. Micro- and nano-fabrication techniques provide access to these dimensions, with the potential to capture and manipulate the spatial complexity of intracellular signaling in experimental models. This review focuses on recent advances in adapting surface engineering for use with biomolecular systems that interface with cell signaling, particularly with respect to surfaces that interact with multiple receptor systems on individual cells. The utility of this conceptual and experimental approach is demonstrated in the context of epithelial cells and T lymphocytes, two system for which the convergence and balance of multiple signaling pathways has dramatic impacts on the ability of these cells to provide their physiological function. PMID:23862677

  11. Effect of Bacterial Cell Moisture on the Sporicidal Activity of β-Propiolactone Vapor

    PubMed Central

    Hoffman, Robert K.

    1968-01-01

    The activity of a vapor-phase disinfectant is usually expressed in terms of the atmospheric relative humidity (RH). This study shows that, in β-propiolactone (BPL) vapor disinfection, the important factor is really the moisture content and location of water in the cell, and not necessarily the atmospheric RH. Previous studies revealed that only about 50% of the bacterial spores equilibrated to 45% RH were killed when exposed to the same RH to BPL vapor. On the other hand, all the spores equilibrated to and then exposed at 75% RH to BPL were readily killed. The present study shows that spores equilibrated to 98% RH are readily killed by BPL at 45% RH, but only 99% of the spores equilibrated to 75% RH are killed by BPL at 45% RH. Also, in order to be killed, desiccated spores must be exposed to BPL at higher humidities than would be required if the spores had not been previously desiccated. PMID:4967453

  12. Efficiency enhancement in solution-processed organic small molecule: Fullerene solar cells via solvent vapor annealing

    NASA Astrophysics Data System (ADS)

    Miao, Jingsheng; Chen, Hui; Liu, Feng; Zhao, Baofeng; Hu, Lingyu; He, Zhicai; Wu, Hongbin

    2015-05-01

    We report highly efficient small molecule solar cells (SMSCs) by using dichloromethane solvent vapor annealing method. The resulted devices delivered a power conversion efficiency (PCE) of 8.3%, which is among the highest in SMSCs. Comparing to the control devices, the short circuit current (Jsc), fill factor, and PCE of solvent vapor annealed devices are significantly improved. Summarizing the results of optical absorption, film morphology, and charge carrier transporting properties, we see that the enhanced structure order and reduced size of phase separation are major reasons for the improved device performances, establishing a solid structure-property relationship. The solvent vapor annealing method can thus be a useful method in device fabrication to enhance performances of SMSCs.

  13. GHz Rabi Flopping to Rydberg States in Hot Atomic Vapor Cells

    SciTech Connect

    Huber, B.; Baluktsian, T.; Schlagmueller, M.; Koelle, A.; Kuebler, H.; Loew, R.; Pfau, T.

    2011-12-09

    We report on the observation of Rabi oscillations to a Rydberg state on a time scale below 1 ns in thermal rubidium vapor. We use a bandwidth-limited pulsed excitation and observe up to 6 full Rabi cycles within a pulse duration of {approx}4 ns. We find good agreement between the experiment and numerical simulations based on a surprisingly simple model. This result shows that fully coherent dynamics with Rydberg states can be achieved even in thermal atomic vapor, thus suggesting small vapor cells as a platform for room-temperature quantum devices. Furthermore, the result implies that previous coherent dynamics in single-atom Rydberg gates can be accelerated by 3 orders of magnitude.

  14. 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

  15. MicroRNA-7a regulates pancreatic β cell function

    PubMed Central

    Latreille, Mathieu; Hausser, Jean; Stützer, Ina; Zhang, Quan; Hastoy, Benoit; Gargani, Sofia; Kerr-Conte, Julie; Pattou, Francois; Zavolan, Mihaela; Esguerra, Jonathan L.S.; Eliasson, Lena; Rülicke, Thomas; Rorsman, Patrik; Stoffel, Markus

    2014-01-01

    Dysfunctional microRNA (miRNA) networks contribute to inappropriate responses following pathological stress and are the underlying cause of several disease conditions. In pancreatic β cells, miRNAs have been largely unstudied and little is known about how specific miRNAs regulate glucose-stimulated insulin secretion (GSIS) or impact the adaptation of β cell function to metabolic stress. In this study, we determined that miR-7 is a negative regulator of GSIS in β cells. Using Mir7a2 deficient mice, we revealed that miR-7a2 regulates β cell function by directly regulating genes that control late stages of insulin granule fusion with the plasma membrane and ternary SNARE complex activity. Transgenic mice overexpressing miR-7a in β cells developed diabetes due to impaired insulin secretion and β cell dedifferentiation. Interestingly, perturbation of miR-7a expression in β cells did not affect proliferation and apoptosis, indicating that miR-7 is dispensable for the maintenance of endocrine β cell mass. Furthermore, we found that miR-7a levels are decreased in obese/diabetic mouse models and human islets from obese and moderately diabetic individuals with compensated β cell function. Our results reveal an interconnecting miR-7 genomic circuit that regulates insulin granule exocytosis in pancreatic β cells and support a role for miR-7 in the adaptation of pancreatic β cell function in obesity and type 2 diabetes. PMID:24789908

  16. Osteogenic cell sheets reinforced with photofunctionalized micro-thin titanium.

    PubMed

    Ishijima, Manabu; Hirota, Makoto; Park, Wonhee; Honda, Masaki J; Tsukimura, Naoki; Isokawa, Keitaro; Ishigami, Tomohiko; Ogawa, Takahiro

    2015-05-01

    Cell sheet technology has been used to deliver cells in single-sheet form with an intact extracellular matrix for soft tissue repair and regeneration. Here, we hypothesized that titanium-reinforced cell sheets could be constructed for bone tissue engineering and regeneration. Fifty-µm-thick titanium plates containing apertures were prepared and roughened by acid etching, some of which were photofunctionalized with 12 min of UV light treatment. Cell sheets were prepared by culturing rat calvarial periosteum-derived cells on temperature-responsive culture dishes and attached to titanium plates. Titanium-reinforced osteogenic cell sheet construction was conditional on various technical and material factors: cell sheets needed to be double-sided and sandwich the titanium plate, and the titanium plates needed to be micro thin and contain apertures to allow close apposition of the two cell sheets. Critically, titanium plates needed to be UV-photofunctionalized to ensure adherence and retention of cell sheets. Single-sided cell sheets or double-sided cell sheets on as-made titanium contracted and deformed within 4 days of incubation. Titanium-reinforced cell sheets on photofunctionalized titanium were structurally stable at least up to 14 days, developed the expected osteogenic phenotypes (ALP production and mineralization), and maintained structural integrity without functional degradation. Successful construction of titanium-reinforced osteogenic cell sheets was associated with increased cell attachment, retention, and expression of vinculin, an adhesion protein by photofunctionalization. This study identified the technical and material requirements for constructing titanium-reinforced osteogenic cell sheets. Future in vivo studies are warranted to test these titanium-reinforced cell sheets as stably transplantable, mechanically durable, and shape controllable osteogenic devices. PMID:25604095

  17. Helicobacter pylori interferes with an embryonic stem cell micro RNA cluster to block cell cycle progression

    PubMed Central

    2011-01-01

    Background MicroRNAs, post-transcriptional regulators of eukaryotic gene expression, are implicated in host defense against pathogens. Viruses and bacteria have evolved strategies that suppress microRNA functions, resulting in a sustainable infection. In this work we report that Helicobacter pylori, a human stomach-colonizing bacterium responsible for severe gastric inflammatory diseases and gastric cancers, downregulates an embryonic stem cell microRNA cluster in proliferating gastric epithelial cells to achieve cell cycle arrest. Results Using a deep sequencing approach in the AGS cell line, a widely used cell culture model to recapitulate early events of H. pylori infection of gastric mucosa, we reveal that hsa-miR-372 is the most abundant microRNA expressed in this cell line, where, together with hsa-miR-373, it promotes cell proliferation by silencing large tumor suppressor homolog 2 (LATS2) gene expression. Shortly after H. pylori infection, miR-372 and miR-373 synthesis is highly inhibited, leading to the post-transcriptional release of LATS2 expression and thus, to a cell cycle arrest at the G1/S transition. This downregulation of a specific cell-cycle-regulating microRNA is dependent on the translocation of the bacterial effector CagA into the host cells, a mechanism highly associated with the development of severe atrophic gastritis and intestinal-type gastric carcinoma. Conclusions These data constitute a novel example of host-pathogen interplay involving microRNAs, and unveil the couple LATS2/miR-372 and miR-373 as an unexpected mechanism in infection-induced cell cycle arrest in proliferating gastric cells, which may be relevant in inhibition of gastric epithelium renewal, a major host defense mechanism against bacterial infections. PMID:22027184

  18. MicroRNA-21 Increases Proliferation and Cisplatin Sensitivity of Osteosarcoma-Derived Cells.

    PubMed

    Vanas, Vanita; Haigl, Barbara; Stockhammer, Verena; Sutterlüty-Fall, Hedwig

    2016-01-01

    Osteosarcoma is the most common primary bone tumor and poor prognosis for osteosarcoma patients is mainly due to chemotherapy resistance. MicroRNAs are important to maintain pathophysiological mechanisms of cancer and influence cell sensitivity to chemotherapy. In this study, we tested the functions of microRNA-21 for malignant features as well as for drug resistance of osteosarcoma. We used Northern blot to measure microRNA-21 levels in osteosarcoma-derived cell lines. MicroRNA-21 activity was modulated by either expressing a sponge to decrease its activity in an osteosarcoma-derived cell line expressing high levels of microRNA-21 or by introducing pri-microRNA-21 in a cell line with low endogenous levels. Cell migration was determined in a scratch assay and cell proliferation was measured by performing growth curve analysis. Sensitivity of the cells towards chemotherapeutics was investigated by performing cell viability assays and calculating the IC50 values. While cell migration was unaffected by modulated microRNA-21 levels, microRNA-21 inhibition slowed proliferation and exogenously expressed microRNA-21 promoted this process. Modulated microRNA-21 activity failed to effect sensitivity of osteosarcoma-derived cell lines to doxorubicin or methotrexate. Contrarily, reduction of microRNA-21 activity resulted in enhanced resistance towards cisplatin while ectopic expression of microRNA-21 showed the opposite effect. Increased microRNA-21 levels repressed the expression of Sprouty2 and ectopic expression of Sprouty2 was able to largely rescue the observed effects of microRNA-21 in osteosarcoma. In summary, our data indicate that in osteosarcoma microRNA-21 expression is an important component for regulation of cell proliferation and for determining sensitivity to cisplatin. PMID:27513462

  19. MicroRNA-21 Increases Proliferation and Cisplatin Sensitivity of Osteosarcoma-Derived Cells

    PubMed Central

    Vanas, Vanita; Haigl, Barbara; Stockhammer, Verena; Sutterlüty-Fall, Hedwig

    2016-01-01

    Osteosarcoma is the most common primary bone tumor and poor prognosis for osteosarcoma patients is mainly due to chemotherapy resistance. MicroRNAs are important to maintain pathophysiological mechanisms of cancer and influence cell sensitivity to chemotherapy. In this study, we tested the functions of microRNA-21 for malignant features as well as for drug resistance of osteosarcoma. We used Northern blot to measure microRNA-21 levels in osteosarcoma-derived cell lines. MicroRNA-21 activity was modulated by either expressing a sponge to decrease its activity in an osteosarcoma-derived cell line expressing high levels of microRNA-21 or by introducing pri-microRNA-21 in a cell line with low endogenous levels. Cell migration was determined in a scratch assay and cell proliferation was measured by performing growth curve analysis. Sensitivity of the cells towards chemotherapeutics was investigated by performing cell viability assays and calculating the IC50 values. While cell migration was unaffected by modulated microRNA-21 levels, microRNA-21 inhibition slowed proliferation and exogenously expressed microRNA-21 promoted this process. Modulated microRNA-21 activity failed to effect sensitivity of osteosarcoma-derived cell lines to doxorubicin or methotrexate. Contrarily, reduction of microRNA-21 activity resulted in enhanced resistance towards cisplatin while ectopic expression of microRNA-21 showed the opposite effect. Increased microRNA-21 levels repressed the expression of Sprouty2 and ectopic expression of Sprouty2 was able to largely rescue the observed effects of microRNA-21 in osteosarcoma. In summary, our data indicate that in osteosarcoma microRNA-21 expression is an important component for regulation of cell proliferation and for determining sensitivity to cisplatin. PMID:27513462

  20. The Role of MicroRNAs in Cardiac Stem Cells

    PubMed Central

    Purvis, Nima; Bahn, Andrew; Katare, Rajesh

    2015-01-01

    Stem cells are considered as the next generation drug treatment in patients with cardiovascular disease who are resistant to conventional treatment. Among several stem cells used in the clinical setting, cardiac stem cells (CSCs) which reside in the myocardium and epicardium of the heart have been shown to be an effective option for the source of stem cells. In normal circumstances, CSCs primarily function as a cell store to replace the physiologically depleted cardiovascular cells, while under the diseased condition they have been shown to experimentally regenerate the diseased myocardium. In spite of their major functional role, molecular mechanisms regulating the CSCs proliferation and differentiation are still unknown. MicroRNAs (miRs) are small, noncoding RNA molecules that regulate gene expression at the posttranscriptional level. Recent studies have demonstrated the important role of miRs in regulating stem cell proliferation and differentiation, as well as other physiological and pathological processes related to stem cell function. This review summarises the current understanding of the role of miRs in CSCs. A deeper understanding of the mechanisms by which miRs regulate CSCs may lead to advances in the mode of stem cell therapies for the treatment of cardiovascular diseases. PMID:25802528

  1. microRNAs in Pancreatic β-Cell Physiology.

    PubMed

    Özcan, Sabire

    2015-01-01

    The β-cells within the pancreas are responsible for production and secretion of insulin. Insulin is released from pancreatic β-cells in response to increasing blood glucose levels and acts on insulin-sensitive tissues such as skeletal muscle and liver in order to maintain normal glucose homeostasis. Therefore, defects in pancreatic β-cell function lead to hyperglycemia and diabetes mellitus. A new class of molecules called microRNAs has been recently demonstrated to play a crucial role in regulation of pancreatic β-cell function under normal and pathophysiological conditions. miRNAs have been shown to regulate endocrine pancreas development, insulin biosynthesis, insulin exocytosis, and β-cell expansion. Many of the β-cell enriched miRNAs have multiple functions and regulate pancreas development as well as insulin biosynthesis and exocytosis. Furthermore, several of the β-cell specific miRNAs have been shown to accumulate in the circulation before the onset of diabetes and may serve as potential biomarkers for prediabetes. This chapter will focus on miRNAs that are enriched in pancreatic β-cells and play a critical role in modulation of β-cell physiology and may have clinical significance in the treatment of diabetes. PMID:26662988

  2. Effects of water concentration in the coating solution on the wall relaxation rate of octadecyltrichlorosilane coated rubidium vapor cells

    SciTech Connect

    Zhang, Guiying; Wei, Lihua; Wang, Meiling; Zhao, Kaifeng

    2015-01-28

    High quality anti-relaxation surface coatings for atomic vapor cells are essential for the preservation of atomic spin coherence and the enhancement of measurement sensitivity. In this paper, we studied the effects of water concentration in octadecyltrichlorosilane (OTS) coating solution on the relaxation rate and its reproducibility of OTS coated Rubidium vapor cells. We found that appropriate water concentration can improve the anti-relaxation performance of OTS coated cells.

  3. Roles of microRNA on cancer cell metabolism

    PubMed Central

    2012-01-01

    Advanced studies of microRNAs (miRNAs) have revealed their manifold biological functions, including control of cell proliferation, cell cycle and cell death. However, it seems that their roles as key regulators of metabolism have drawn more and more attention in the recent years. Cancer cells display increased metabolic autonomy in comparison to non-transformed cells, taking up nutrients and metabolizing them in pathways that support growth and proliferation. MiRNAs regulate cell metabolic processes through complicated mechanisms, including directly targeting key enzymes or transporters of metabolic processes and regulating transcription factors, oncogenes / tumor suppressors as well as multiple oncogenic signaling pathways. MiRNAs like miR-375, miR-143, miR-14 and miR-29b participate in controlling cancer cell metabolism by regulating the expression of genes whose protein products either directly regulate metabolic machinery or indirectly modulate the expression of metabolic enzymes, serving as master regulators, which will hopefully lead to a new therapeutic strategy for malignant cancer. This review focuses on miRNA regulations of cancer cell metabolism,including glucose uptake, glycolysis, tricarboxylic acid cycle and insulin production, lipid metabolism and amino acid biogenesis, as well as several oncogenic signaling pathways. Furthermore, the challenges of miRNA-based strategies for cancer diagnosis, prognosis and therapeutics have been discussed. PMID:23164426

  4. Dicke coherent narrowing in two-photon and Raman spectroscopy of thin vapor cells

    NASA Astrophysics Data System (ADS)

    Dutier, Gabriel; Todorov, Petko; Hamdi, Ismahène; Maurin, Isabelle; Saltiel, Solomon; Bloch, Daniel; Ducloy, Martial

    2005-10-01

    The principle of coherent Dicke narrowing in a thin vapor cell, in which sub-Doppler spectral line shapes are observed under a normal irradiation for a λ/2 thickness, is generalized to two-photon spectroscopy. Only the sum of the two wave vectors must be normal to the cell, making the two-photon scheme highly versatile. A comparison is provided between the Dicke narrowing with copropagating fields, and the residual Doppler broadening occurring with counterpropagating geometries. The experimental feasibility is discussed on the basis of a first observation of a two-photon resonance in a 300-nm-thick Cs cell. Extension to the Raman situation is finally considered.

  5. Cell migration in confinement: a micro-channel-based assay.

    PubMed

    Heuzé, Mélina L; Collin, Olivier; Terriac, Emmanuel; Lennon-Duménil, Ana-Maria; Piel, Matthieu

    2011-01-01

    This chapter describes a method to study cells migrating in micro-channels, a confining environment of well-defined geometry. This assay is a complement to more complex 3D migration systems and provides several advantages even if it does not recapitulate the full complexity of 3D migration. Important parameters such as degree of adhesion, degree of confinement, mechanical properties, and geometry can be varied independently of each other. The device is fully compatible with almost any type of light microscopy and the simple geometry makes automated analysis very easy to perform, which allows screening strategy. The chapters is divided into five parts describing the design of different types of migration chambers, the fabrication of a mold by photolithography, the assembly of the chamber, the loading of cells, and finally the imaging on live or fixed cells. PMID:21748692

  6. Radio-frequency Electrometry Using Rydberg Atoms in Vapor Cells: Towards the Shot Noise Limit

    NASA Astrophysics Data System (ADS)

    Kumar, Santosh; Fan, Haoquan; Jahangiri, Akbar; Kuebler, Harald; Shaffer, James P.; 5. Physikalisches Institut, Universitat Stuttgart, Germany Collaboration

    2016-05-01

    Rydberg atoms are a promising candidate for radio frequency (RF) electric field sensing. Our method uses electromagnetically induced transparency with Rydberg atoms in vapor cells to read out the effect that the RF electric field has on the Rydberg atoms. The method has the potential for high sensitivity (pV cm-1 Hz- 1 / 2) and can be self-calibrated. Some of the main factors limiting the sensitivity of RF electric field sensing from reaching the shot noise limit are the residual Doppler effect and the sensitivity of the optical read-out using the probe laser. We present progress on overcoming the residual Doppler effect by using a new multi-photon scheme and reaching the shot noise detection limit using frequency modulated spectroscopy. Our experiments also show promise for studying quantum optical effects such as superradiance in vapor cells using Rydberg atoms. This work is supported by DARPA, ARO, and NRO.

  7. Micro-optical designs for angular confinement in solar cells

    NASA Astrophysics Data System (ADS)

    Gordon, Jeffrey M.; Feuermann, Daniel; Mashaal, Heylal

    2015-01-01

    We identify and evaluate a variety of efficient and feasible micro-optics for confining the radiative emission of solar cells. The key criteria used for assessing viable designs are (1) high optical efficiency for both the transmission of impinging solar beam radiation and the external recycling of isotropic cell luminescent emission; (2) liberal optical tolerance; (3) compactness and (4) being amenable to fabrication from existing materials and manufacturing processes. Both imaging and nonimaging candidate designs are presented, and their superiority to previous proposals is quantified. The strategy of angular confinement for boosting cell open-circuit voltage-thereby enhancing conversion efficiency-is limited to cells where radiative recombination is the dominant carrier recombination pathway. Optical systems that restrict the angular range for emission of cell luminescence must, by reciprocity, commensurately restrict the angular range for the collection of solar radiation. This, in turn, mandates the introduction of concentrators, but not for the objective of delivering concentrated flux onto the cell. Rather, the optical system must project an acceptably uniform spatial distribution of solar flux onto the cell surface at a nominal averaged irradiance of 1 sun.

  8. Temperature Sensitivity of an Atomic Vapor Cell-Based Dispersion-Enhanced Optical Cavity

    NASA Technical Reports Server (NTRS)

    Myneni, K.; Smith, D. D.; Chang, H.; Luckay, H. A.

    2015-01-01

    Enhancement of the response of an optical cavity to a change in optical path length, through the use of an intracavity fast-light medium, has previously been demonstrated experimentally and described theoretically for an atomic vapor cell as the intracavity resonant absorber. This phenomenon may be used to enhance both the scale factor and sensitivity of an optical cavity mode to the change in path length, e.g. in gyroscopic applications. We study the temperature sensitivity of the on-resonant scale factor enhancement, S(sub o), due to the thermal sensitivity of the lower-level atom density in an atomic vapor cell, specifically for the case of the Rb-87 D(sub 2) transition. A semi-empirical model of the temperature-dependence of the absorption profile, characterized by two parameters, a(sub o)(T) and gamma(sub a)(T) allows the temperature-dependence of the cavity response, S(sub o)(T) and dS(sub o)/dT to be predicted over a range of temperature. We compare the predictions to experiment. Our model will be useful in determining the useful range for S(sub o), given the practical constraints on temperature stability for an atomic vapor cell.

  9. Cultivation and recovery of vascular endothelial cells in microchannels of a separable micro-chemical chip.

    PubMed

    Yamashita, Tadahiro; Tanaka, Yo; Idota, Naokazu; Sato, Kae; Mawatari, Kazuma; Kitamori, Takehiko

    2011-04-01

    Various micro cell culture systems have recently been developed. However, it is extremely difficult to recover cultured cells from a microchannel because the upper and lower substrates of a microchip are permanently combined. Therefore, we developed a cell culture and recovery system that uses a separable microchip with reversible combining that allows separation between closed and open channels. To realize this system, two problems related to microfluidic control-prevention of leakage and non-invasive recovery of cultured cells from the substrate-must be overcome. In the present study, we used surface chemistry modification to solve both problems. First, octadecyltrimethoxysilane (ODTMS) was utilized to control the Laplace pressure at the liquid/vapor phase interface, such that it was directed toward the microchannels, which suppressed leakage from the slight gap between two substrates. Second, a thermoresponsive polymer poly(N-isopropyl acrylamide) (PNIPAAm) was used to coat the surface of the ODTMS-modified microchannel by UV-mediated photopolymerization. PNIPAAm substrates are well known for controlled cell adhesion/detachment by alteration of temperature. Finally, the ODTMS- and PNIPAAm-modified separable microchips were subjected to patterning, and human arterial endothelial cells (HAECs) were cultured in the resulting microchannels with no leakage. After 96 h of the culture, the HAECs were detached from the microchips by decreasing the temperature and were then recovered from the microchannels. This study is the first to demonstrate the recovery of living cells cultured in a microchannel, and may be useful as a fundamental technique for vascular tissue engineering. PMID:21251708

  10. Extracellular microRNAs from the epididymis as potential mediators of cell-to-cell communication

    PubMed Central

    Belleannée, Clémence

    2015-01-01

    Ribonucleic acid (RNA) was previously thought to remain inside cells as an intermediate between genes and proteins during translation. However, it is now estimated that 98% of the mammalian genomic output is transcribed as noncoding RNAs, which are involved in diverse gene expression regulatory mechanisms and can be transferred from one cell to another through extracellular communication. For instance, microRNAs are 22-nucleotide-long noncoding RNAs that are generated by endonuclease cleavage of precursors inside the cells and are secreted as extracellular microRNAs to regulate target cell posttranscriptional gene expression via RNA interference. We and others have shown that different populations of microRNAs are expressed in distinct regions of the human epididymis and regulate the expression of target genes that are involved in the control of male fertility as indicated by knock-out mouse models. Importantly, some microRNAs, including the microRNA-888 (miR-888) cluster that is exclusively expressed in the reproductive system of human and nonhuman primates, are released in the sperm-surrounding fluid in the epididymis via extracellular vesicles, the so-called epididymosomes. In addition to interacting with the membrane of maturing spermatozoa, these extracellular vesicles containing microRNAs communicate with epithelial cells located downstream from their release site, suggesting a role in the luminal exocrine control of epididymal functions. Apart from their potential roles as mediators of intercellular communication within the epididymis, these extracellular microRNAs are potent molecular targets for the noninvasive diagnosis of male infertility. PMID:26178395

  11. Microbioreactors and scale-down models: growth of CHO cells using the Pall Micro24 MicroReactor system.

    PubMed

    Warr, Steve R C

    2014-01-01

    Microbioreactors are increasingly used within animal cell biotechnology to grow mammalian cells for cell line screening and to facilitate process development. Many such devices have been reported in the literature, but only a small number are available commercially. Microbioreactors range in complexity from simple plate-based systems to complex automated parallel bioreactors designed to enable the meaningful scale-down of conventional bioprocesses. The Micro24 MicroReactor system (Pall Life Sciences) fits between these extremes providing 24× 7 mL parallel "bioreactors" with individual monitoring and control of temperature, pH, and dissolved oxygen. Inoculation, sampling, and feed additions are carried out manually in a Biological Safety Cabinet. In this chapter we describe the use of the Micro24 system to carry out screening or process development experiments with CHO cells. PMID:24297415

  12. microRNA-451 inhibited cell proliferation, migration and invasion through regulation of MIF in renal cell carcinoma

    PubMed Central

    Tang, Yan; Wan, Wei; Wang, Lijuan; Ji, Shishun; Zhang, Juanjuan

    2015-01-01

    The expression and functions of microRNA-451 have been studied in many human cancers. However, up to date, there is no study of microRNA-451 in renal cell carcinoma. In the present study, we aimed to investigate the expression, biological functions and molecular mechanisms of microRNA-451 in renal cell carcinoma. microRNA-451 expression level in renal cell carcinoma tissues and cell lines was measured using quantitative Real-time PCR. By using CCK8 assay, cell migration and invasion assay, we explored the functions of microRNA-451 in renal cell carcinoma. Dual-Luciferase report assay, quantitative Real-time PCR and western blot were performed to explore the molecular mechanisms of microRNA-451 functions in renal cell carcinoma. Functional assays were also performed to explore the effects of endogenous MIF in renal cell carcinoma. In this study, we showed for the first time that microRNA-451 was significantly down-regulated in renal cell carcinomas tissues and cell lines. microRNA-451 expression level was correlated with histological grade and lymph node metastasis. In addition, microRNA-451 inhibited proliferation, migration and invasion of renal cell carcinomas cells. Moreover, MIF was identified as a target of microRNA-451, and down-regulation of MIF could mimic the suppressive functions of microRNA-451 in renal cell carcinomas, suggesting that microRNA-451 might be a novel therapeutic strategy for the treatment of renal cell carcinomas. PMID:26884830

  13. Tailor cutting of crystalline solar cells by laser micro jet

    NASA Astrophysics Data System (ADS)

    Bruckert, F.; Pilat, E.; Piron, P.; Torres, P.; Carron, B.; Richerzhagen, B.; Pirot, M.; Monna, R.

    2012-03-01

    Coupling a laser into a hair thin water micro jet (Laser Micro Jet, LMJ) for cutting applications offers a wide range of processes that are quite unique. As the laser beam is guided by internal reflections inside of a liquid cylinder, the cuts are naturally straight and do not reflect any divergence as otherwise occurs with an unguided laser beam. Furthermore, having a liquid media at the point of contact ensures a fast removal of heat and eventual debris ensuring clean cuts, which are free of any burrs. Many applications have indeed been developed for a large variety of materials, which are as different as e.g. diamond, silicon, aluminum, ceramic and hard metals. The photovoltaic industry has enjoyed in the last decades tremendous growth rates, which are still projected into the future. We focus here on the segment of Building Integrated PV (BIPV), which requests tailored solutions to actual buildings and not-one-fits-it-all standardized modules. Having the option to tailor cut solar cells opens a new field of BIPV applications. For the first time, finished crystalline solar cells have been LMJ cut into predetermined shapes. First results show that the cut is clean and neat. Preliminary solar performance measurements are positive. This opens a new avenue of tailored made modules instead of having to rely on the one-fits-alloy approach used so far.

  14. Characterization of Cs vapor cell coated with octadecyltrichlorosilane using coherent population trapping spectroscopy

    SciTech Connect

    Hafiz, Moustafa Abdel; Maurice, Vincent; Chutani, Ravinder; Passilly, Nicolas; Gorecki, Christophe; Boudot, Rodolphe; Guérandel, Stéphane; Clercq, Emeric de

    2015-05-14

    We report the realization and characterization using coherent population trapping (CPT) spectroscopy of an octadecyltrichlorosilane (OTS)-coated centimeter-scale Cs vapor cell. The dual-structure of the resonance lineshape, with presence of a narrow structure line at the top of a Doppler-broadened structure, is clearly observed. The linewidth of the narrow resonance is compared to the linewidth of an evacuated Cs cell and of a buffer gas Cs cell of similar size. The Cs-OTS adsorption energy is measured to be (0.42 ± 0.03) eV, leading to a clock frequency shift rate of 2.7 × 10{sup −9}/K in fractional unit. A hyperfine population lifetime, T{sub 1}, and a microwave coherence lifetime, T{sub 2}, of 1.6 and 0.5 ms are reported, corresponding to about 37 and 12 useful bounces, respectively. Atomic-motion induced Ramsey narrowing of dark resonances is observed in Cs-OTS cells by reducing the optical beam diameter. Ramsey CPT fringes are detected using a pulsed CPT interrogation scheme. Potential applications of the Cs-OTS cell to the development of a vapor cell atomic clock are discussed.

  15. Boundary Layer Observations of Water Vapor and Aerosol Profiles with an Eye-Safe Micro-Pulse Differential Absorption Lidar (DIAL)

    NASA Astrophysics Data System (ADS)

    Nehrir, A. R.; Repasky, K. S.; Carlsten, J.; Ismail, S.

    2011-12-01

    Measurements of real-time high spatial and temporal resolution profiles of combined water vapor and aerosols in the boundary layer have been a long standing observational challenge to the meteorological, weather forecasting, and climate science communities. To overcome the high reoccurring costs associated with radiosondes as well as the lack of sufficient water vapor measurements over the continental united states, a compact and low cost eye-safe all semiconductor-based micro-pulse differential absorption lidar (DIAL) has been developed for water vapor and aerosol profiling in the lower troposphere. The laser transmitter utilizes two continuous wave external cavity diode lasers operating in the 830 nm absorption band as the online and offline seed laser sources. An optical switch is used to sequentially injection seed a tapered semiconductor optical amplifier (TSOA) with the two seed laser sources in a master oscillator power amplifier (MOPA) configuration. The TSOA is actively current pulsed to produce up to 7 μJ of output energy over a 1 μs pulse duration (150 m vertical resolution) at a 10 kHz pulse repetition frequency. The measured laser transmitter spectral linewidth is less than 500 kHz while the long term frequency stability of the stabilized on-line wavelength is ± 55 MHz. The laser transmitter spectral purity was measured to be greater than 0.9996, allowing for simultaneous measurements of water vapor in the lower and upper troposphere. The DIAL receiver utilizes a commercially available full sky-scanning capable 35 cm Schmidt-Cassegrain telescope to collect the scattered light from the laser transmitter. Light collected by the telescope is spectrally filtered to suppress background noise and is coupled into a fiber optic cable which acts as the system field stop and limits the full angle field of view to 140 μrad. The light is sampled by a fiber coupled APD operated in a Geiger mode. The DIAL instrument is operated autonomously where water vapor and

  16. MicroRNA-21 suppression impedes medulloblastoma cell migration.

    PubMed

    Grunder, Eveline; D'Ambrosio, Rocco; Fiaschetti, Giulio; Abela, Lucia; Arcaro, Alexandre; Zuzak, Tycho; Ohgaki, Hiroko; Lv, Sheng-Qing; Shalaby, Tarek; Grotzer, Michael

    2011-11-01

    Medulloblastoma (MB), the most common malignant brain tumour in children, is characterised by a high risk of leptomeningeal dissemination. But little is known about the molecular mechanisms that promote cancer cell migration in MB. Aberrant expression of miR-21 is recognised to be causatively linked to metastasis in a variety of human neoplasms including brain tumours; however its function in MB is still unknown. In this study we investigated the expression level and the role of miR-21 in MB cell migration. miR-21 was found to be up-regulated, compared to normal cerebellum, in 29/29 MB primary samples and 6/6 MB-derived cell lines. Inverse correlation was observed between miR-21 expression and the metastasis suppressor PDCD4, while miR-21 repression increased the release of PDCD4 protein, suggesting negative regulation of PDCD4 by miR-21 in MB cells. Anti-miR-21 decreased protein expression of the tumour cell invasion mediators MAP4K1 and JNK, which are also known to be negatively regulated by PDCD4, and down-regulated integrin protein that is essential for MB leptomeningeal dissemination. Moreover miR-21 knockdown in MB cells increased the expression of two eminent negative modulators of cancer cell migration, E-Cadherin and TIMP2 proteins that are known to be positively regulated by PDCD4. Finally and importantly, suppression of miR-21 decreased the motility of MB cells and reduced their migration across basement membranes in vitro. Together, these compelling data propose miR-21 pathway as a novel mechanism impacting MB cell dissemination and raises the possibility that curability of selected MB may be improved by pharmaceutical strategies directed towards microRNA-21. PMID:21775132

  17. Optical rotation in excess of 100 rad generated by Rb vapor in a multipass cell

    SciTech Connect

    Li, S.; Vachaspati, P.; Sheng, D.; Dural, N.; Romalis, M. V.

    2011-12-15

    Paramagnetic Faraday rotation is a powerful technique for atom sensing widely used in quantum nondemolition measurements, fundamental symmetry tests, and other precision measurements. We demonstrate the use of a multipass optical cell for Faraday rotation spectroscopy and observe polarization rotation in excess of 100 rad from spin-polarized Rb vapor. Unlike optical cavities, multipass cells have a deterministic number of light passes and can be used to measure large optical rotations. We also observe a tenfold suppression of transverse spin relaxation when Rb atoms are placed in a coherent superposition state immune to spin-exchange collisions.

  18. Optical rotation in excess of 100 rad generated by Rb vapor in a multipass cell

    NASA Astrophysics Data System (ADS)

    Li, S.; Vachaspati, P.; Sheng, D.; Dural, N.; Romalis, M. V.

    2011-12-01

    Paramagnetic Faraday rotation is a powerful technique for atom sensing widely used in quantum nondemolition measurements, fundamental symmetry tests, and other precision measurements. We demonstrate the use of a multipass optical cell for Faraday rotation spectroscopy and observe polarization rotation in excess of 100 rad from spin-polarized Rb vapor. Unlike optical cavities, multipass cells have a deterministic number of light passes and can be used to measure large optical rotations. We also observe a tenfold suppression of transverse spin relaxation when Rb atoms are placed in a coherent superposition state immune to spin-exchange collisions.

  19. 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

  20. Manipulating cell shape by placing cells into micro-fabricated chambers.

    PubMed

    Chang, Fred; Atilgan, Erdinc; Burgess, David; Minc, Nicolas

    2014-01-01

    Cell shape is an important cellular parameter that influences the spatial organization and function of cells. However, it has often been challenging to study the effects of cell shape because of difficulties in experimentally controlling cell shape in a defined way. We describe here a method of physically manipulating sea urchin cells into specified shapes by inserting them into micro-fabricated chambers of different shapes. This method allows for generation of large systematic and quantitative data sets and may be adaptable for different cell types and contexts. PMID:24633802

  1. MicroRNA Regulation of Human Breast Cancer Stem Cells

    PubMed Central

    Shimono, Yohei; Mukohyama, Junko; Nakamura, Shun-ichi; Minami, Hironobu

    2015-01-01

    MicroRNAs (miRNAs) are involved in virtually all biological processes, including stem cell maintenance, differentiation, and development. The dysregulation of miRNAs is associated with many human diseases including cancer. We have identified a set of miRNAs differentially expressed between human breast cancer stem cells (CSCs) and non-tumorigenic cancer cells. In addition, these miRNAs are similarly upregulated or downregulated in normal mammary stem/progenitor cells. In this review, we mainly describe the miRNAs that are dysregulated in human breast CSCs directly isolated from clinical specimens. The miRNAs and their clusters, such as the miR-200 clusters, miR-183 cluster, miR-221-222 cluster, let-7, miR-142 and miR-214, target the genes and pathways important for stem cell maintenance, such as the self-renewal gene BMI1, apoptosis, Wnt signaling, Notch signaling, and epithelial-to-mesenchymal transition. In addition, the current evidence shows that metastatic breast CSCs acquire a phenotype that is different from the CSCs in a primary site. Thus, clarifying the miRNA regulation of the metastatic breast CSCs will further advance our understanding of the roles of human breast CSCs in tumor progression. PMID:26712794

  2. Spin-exchange frequency shift in alkali-metal-vapor cell frequency standards

    SciTech Connect

    Micalizio, Salvatore; Godone, Aldo; Levi, Filippo; Vanier, Jacques

    2006-03-15

    In this paper we calculate the effect of spin-exchange collisions in alkali-metal vapors. In the framework of the high-energy approximation, we evaluate the spin-exchange cross sections related to the line broadening and to the frequency shift of the ground state hyperfine transition. We do the calculation for the four isotopes, {sup 23}Na, {sup 39}K, {sup 87}Rb, and {sup 133}Cs. The results are used in particular to evaluate the spin-exchange frequency shift in Rb vapor cell frequency standards used in many applications. It turns out that, due to possible fluctuations in the atomic density, spin exchange may affect significantly the medium and long term frequency stability of the frequency standard.

  3. MicroRNA profiles in various hepatocellular carcinoma cell lines

    PubMed Central

    Morishita, Asahiro; Iwama, Hisakazu; Fujihara, Shintaro; Sakamoto, Teppei; Fujita, Koji; Tani, Joji; Miyoshi, Hisaaki; Yoneyama, Hirohito; Himoto, Takashi; Masaki, Tsutomu

    2016-01-01

    Hepatocellular carcinoma (HCC) is one of the most common causes of cancer-associated mortality worldwide. Although surgery is considered the most effective treatment for patients with HCC, its indication is restricted by limited criteria and a high relapse rate following surgery; therefore, systemic chemotherapy is required for patients with advanced-stage HCC to prolong their survival. MicroRNAs (miRNAs) are endogenous non-coding RNAs of 18–22 nucleotides in length. It has been reported that aberrant expression of miRNAs is a feature shared by various types of human cancer. Previous studies have indicated that the modulation of non-coding RNAs, particularly miRNAs, may be a valuable therapeutic target for HCC. The aim of the present study was to elucidate the miRNA profiles associated with differentiation and hepatitis B virus (HBV) infection observed in HCC cell lines. The human Alex, Hep3B, HepG2, HuH1, HuH7, JHH1, JHH2, JHH5, JHH6, HLE, HLF and Li-7 HCC cell lines were used for an miRNA array. Replicate data were analyzed following their classification into: i) Poorly- and well-differentiated human HCC cells and ii) HBV-positive and -negative human HCC cells. Out of the 1,719 miRNAs, 4 were found to be significantly upregulated and 52 significantly downregulated in the poorly-differentiated cells, as compared with the well-differentiated cells. Conversely, in the HBV-positive cells 125 miRNAs were found to be upregulated and 2 downregulated, as compared with the HBV-negative cells. Unsupervised hierarchical clustering analysis with Pearson's correlation revealed that the miRNA expression levels were clustered both together and separately in each group. In conclusion, miRNA profile characterization based on various parameters may be a novel approach to determine the etiology of HCC.

  4. Thin-film solar cells with InGaAs/GaAsP multiple quantum wells and a rear surface etched with light trapping micro-hole array

    NASA Astrophysics Data System (ADS)

    Watanabe, Kentaroh; Inoue, Tomoyuki; Sodabanlu, Hassanet; Sugiyama, Masakazu; Nakano, Yoshiaki

    2015-08-01

    A light trapping effect in GaAs p-i-n solar cells with InGaAs/GaAsP multiple quantum wells (MQWs) in the i-layer was demonstrated by applying a light scattering texture to the rear surface of the cell. A thin-film MQW solar cell was successfully fabricated by metal organic vapor phase epitaxy (MOVPE) to grow an inverted n-i-p photovoltaic (PV) structure; this structure was then transferred to a Si support substrate to prevent optical loss due to free carrier absorption. For the light scattering texture, the use of both the wet-etched micro-hole arrayed SiO2 dielectric layer on the rear surface of the cell and the secondarily etched micro hole array on the GaAs layer was attempted. On the SiO2 layer, the micro hole array pattern was obtained by the radio frequency sputtering of the layer followed by wet etching with photolithographic patterning. On the GaAs layer, the micro-hole array pattern was obtained by direct etching through a SiO2 template. Compared with the light scattering effects of the micro-hole-arrayed SiO2 layer, the secondarily etched GaAs rear contact layer showed a significant improvement in external quantum efficiency (EQE) in the wavelength range from 855 to 1000 nm that corresponds to the photon absorption wavelength in MQWs.

  5. Micro-Imagers for Spaceborne Cell-Growth Experiments

    NASA Technical Reports Server (NTRS)

    Behar, Alberto; Matthews, Janet; SaintAnge, Beverly; Tanabe, Helen

    2006-01-01

    A document discusses selected aspects of a continuing effort to develop five micro-imagers for both still and video monitoring of cell cultures to be grown aboard the International Space Station. The approach taken in this effort is to modify and augment pre-existing electronic micro-cameras. Each such camera includes an image-detector integrated-circuit chip, signal-conditioning and image-compression circuitry, and connections for receiving power from, and exchanging data with, external electronic equipment. Four white and four multicolor light-emitting diodes are to be added to each camera for illuminating the specimens to be monitored. The lens used in the original version of each camera is to be replaced with a shorter-focal-length, more-compact singlet lens to make it possible to fit the camera into the limited space allocated to it. Initially, the lenses in the five cameras are to have different focal lengths: the focal lengths are to be 1, 1.5, 2, 2.5, and 3 cm. Once one of the focal lengths is determined to be the most nearly optimum, the remaining four cameras are to be fitted with lenses of that focal length.

  6. Bifacial solar cell with SnS absorber by vapor transport deposition

    SciTech Connect

    Wangperawong, Artit; Hsu, Po-Chun; Yee, Yesheng; Herron, Steven M.; Clemens, Bruce M.; Cui, Yi; Bent, Stacey F.

    2014-10-27

    The SnS absorber layer in solar cell devices was produced by vapor transport deposition (VTD), which is a low-cost manufacturing method for solar modules. The performance of solar cells consisting of Si/Mo/SnS/ZnO/indium tin oxide (ITO) was limited by the SnS layer's surface texture and field-dependent carrier collection. For improved performance, a fluorine doped tin oxide (FTO) substrate was used in place of the Mo to smooth the topography of the VTD SnS and to make bifacial solar cells, which are potentially useful for multijunction applications. A bifacial SnS solar cell consisting of glass/FTO/SnS/CdS/ZnO/ITO demonstrated front- and back-side power conversion efficiencies of 1.2% and 0.2%, respectively.

  7. Bifacial solar cell with SnS absorber by vapor transport deposition

    NASA Astrophysics Data System (ADS)

    Wangperawong, Artit; Hsu, Po-Chun; Yee, Yesheng; Herron, Steven M.; Clemens, Bruce M.; Cui, Yi; Bent, Stacey F.

    2014-10-01

    The SnS absorber layer in solar cell devices was produced by vapor transport deposition (VTD), which is a low-cost manufacturing method for solar modules. The performance of solar cells consisting of Si/Mo/SnS/ZnO/indium tin oxide (ITO) was limited by the SnS layer's surface texture and field-dependent carrier collection. For improved performance, a fluorine doped tin oxide (FTO) substrate was used in place of the Mo to smooth the topography of the VTD SnS and to make bifacial solar cells, which are potentially useful for multijunction applications. A bifacial SnS solar cell consisting of glass/FTO/SnS/CdS/ZnO/ITO demonstrated front- and back-side power conversion efficiencies of 1.2% and 0.2%, respectively.

  8. Sub-natural width resonances in Cs vapor confined in micrometric thickness optical cell

    NASA Astrophysics Data System (ADS)

    Cartaleva, S.; Krasteva, A.; Sargsyan, A.; Sarkisyan, D.; Slavov, D.; Vartanyan, T.

    2013-03-01

    We present here the behavior of Electromagnetically Induced Transparency (EIT), Velocity Selective Optical Pumping (VSOP) resonances and Velocity Selective Excitation (VSE) resonances observed in Cs vapor confined in а micrometric optical cell (MC) with thickness L = 6λ, λ = 852nm. For comparison of behavior of VSE resonance another conventional optical cell with thickness L=2.5 cm is used. Cells are irradiated in orthogonal to their windows directions by probe beam scanned on the Fg = 4 → Fe= 3, 4, 5 set of transitions and pump beam fixed at the Fg = 3 → Fe = 4 transition, on the D2 line of Cs. The enhanced absorption (fluorescence) narrow VSOP resonance at the closed transition transforms into reduced absorption (fluorescence) one with small increase of atomic concentration or light intensity. A striking difference appears between the VSE resonance broadening in L = 6λ and conventional L = 2.5cm cells.

  9. Effects of viscosity on endothelial cell damage under acoustic droplet vaporization

    NASA Astrophysics Data System (ADS)

    Seda, Robinson; Singh, Rahul; Li, David; Pitre, John; Putnam, Andrew; Fowlkes, J. Brian; Bull, Joseph

    2014-11-01

    Acoustic droplet vaporization (ADV) is a process by which stabilized superheated microdroplets are able to undergo phase transition with the aid of focused ultrasound. Gas bubbles resulting from ADV can provide local occlusion of the blood vessels supplying diseased tissue, such as tumors. The ADV process can also induce bioeffects that increase vessel permeability, which is beneficial for localized drug delivery. Previous in vitro studies have demonstrated that vaporization at the endothelial layer will affect cell attachment and viability. Several hypotheses have been proposed to elucidate the mechanism of damage including the generation of normal and shear stresses during bubble expansion. A single 3.5 MHz ultrasound pulse consisting of 8 cycles (~2.3 μs) and a 6 MPa peak rarefactional pressure was used to induce ADV on endothelial cells in media of different viscosities. Carboxylmethyl cellulose was added to the cell media to increase the viscosity up to 300 cP to and aid in the reduction of stresses during bubble expansion. The likelihood of cell damage was decreased when compared to our control (~1 cP), but it was still present in some cases indicating that the mechanism of damage does not depend entirely on viscous stresses associated with bubble expansion. This work was supported by NIH Grant R01EB006476.

  10. Investigating the Effect of Pyridine Vapor Treatment on Perovskite Solar Cells - Oral Presentation

    SciTech Connect

    Ong, Alison J.

    2015-08-25

    Perovskite photovoltaics have recently come to prominence as a viable alternative to crystalline silicon based solar cells. In an effort to create consistent and high-quality films, we studied the effect of various annealing conditions as well as the effect of pyridine vapor treatment on mixed halide methylammonium lead perovskite films. Of six conditions tested, we found that annealing at 100 degree Celsius for 90 minutes followed by 120 degree Celsius for 15 minutes resulted in the purest perovskite. Perovskite films made using that condition were treated with pyridine for various amounts of time, and the effects on perovskite microstructure were studied using x-ray diffraction, UV-Vis spectroscopy, and time-resolved photoluminescence lifetime analysis (TRPL). A previous study found that pyridine vapor caused perovskite films to have higher photoluminescence intensity and become more homogenous. In this study we found that the effects of pyridine are more complex: while films appeared to become more homogenous, a decrease in bulkphotoluminescence lifetime was observed. In addition, the perovskite bandgap appeared to decrease with increased pyridine treatment time. Finally, X-ray diffraction showed that pyridine vapor treatment increased the perovskite (110) peak intensity but also often gave rise to new unidentified peaks, suggesting the formation of a foreign species. It was observed that the intensity of this unknown species had an inverse correlation with the increase in perovskite peak intensity, and also seemed to be correlated with the decrease in TRPL lifetime.

  11. Investigating the Effect of Pyridine Vapor Treatment on Perovskite Solar Cells

    SciTech Connect

    Ong, Alison

    2015-08-20

    Perovskite photovoltaics have recently come to prominence as a viable alternative to crystalline silicon based solar cells. In an effort to create consistent and high-quality films, we studied the effect of various annealing conditions as well as the effect of pyridine vapor treatment on mixed halide methylammonium lead perovskite films. Of six conditions tested, we found that annealing at 100°C for 90 minutes followed by 120°C for 15 minutes resulted in the purest perovskite. Perovskite films made using that condition were treated with pyridine for various amounts of time, and the effects on perovskite microstructure were studied using x-ray diffraction, UV-Vis spectroscopy, and time-resolved photoluminescence lifetime analysis (TRPL). A previous study found that pyridine vapor caused perovskite films to have higher photoluminescence intensity and become more homogenous. In this study we found that the effects of pyridine are more complex: while films appeared to become more homogenous, a decrease in bulk photoluminescence lifetime was observed. In addition, the perovskite bandgap appeared to decrease with increased pyridine treatment time. Finally, X-ray diffraction showed that pyridine vapor treatment increased the perovskite (110) peak intensity but also often gave rise to new unidentified peaks, suggesting the formation of a foreign species. It was observed that the intensity of this unknown species had an inverse correlation with the increase in perovskite peak intensity, and also seemed to be correlated with the decrease in TRPL lifetime.

  12. Organic solvent vapor sensitive methylammonium lead trihalide film formation for efficient hybrid perovskite solar cells

    SciTech Connect

    Lian, Jiarong; Wang, Qi; Yuan, Yongbo; Shao, Yuchuan; Huang, Jinsong

    2015-03-25

    In this study, the anisotropic electronic properties of the perovskite crystals originating from their non-cubic crystal structures can potentially give rise to the grain orientation correlated photovoltaic device performance. Here we report that an organic solvent vapor atmosphere introduced during the spin-coating and formation of perovskite films changes the orientation and size of perovskite grains. It was found that slightly larger but much more oriented methylammonium lead trihalide (CH3NH3PbI3) grains could be obtained under 1,2-dichlorobenzene (DCB) and dimethyl sulfoxide (DMSO) vapor atmospheres. The devices with more oriented grains outperformed regular devices with more random grains by a 50 mV larger open circuit voltage as well as a slightly increased fill factor. The device efficiency enhancement can be attributed to the longer charge recombination lifetime resulting from the reduced trap density and oriented grains. This result is important in providing guidelines for comparing the results from various groups because organic solvent vapors are generally present in a sealed glovebox for perovskite solar cell fabrication.

  13. Organic solvent vapor sensitive methylammonium lead trihalide film formation for efficient hybrid perovskite solar cells

    DOE PAGESBeta

    Lian, Jiarong; Wang, Qi; Yuan, Yongbo; Shao, Yuchuan; Huang, Jinsong

    2015-03-25

    In this study, the anisotropic electronic properties of the perovskite crystals originating from their non-cubic crystal structures can potentially give rise to the grain orientation correlated photovoltaic device performance. Here we report that an organic solvent vapor atmosphere introduced during the spin-coating and formation of perovskite films changes the orientation and size of perovskite grains. It was found that slightly larger but much more oriented methylammonium lead trihalide (CH3NH3PbI3) grains could be obtained under 1,2-dichlorobenzene (DCB) and dimethyl sulfoxide (DMSO) vapor atmospheres. The devices with more oriented grains outperformed regular devices with more random grains by a 50 mV largermore » open circuit voltage as well as a slightly increased fill factor. The device efficiency enhancement can be attributed to the longer charge recombination lifetime resulting from the reduced trap density and oriented grains. This result is important in providing guidelines for comparing the results from various groups because organic solvent vapors are generally present in a sealed glovebox for perovskite solar cell fabrication.« less

  14. Photo-Activated Low Temperature, Micro Fuel Cell Power Source

    SciTech Connect

    Harry L. Tuller

    2007-03-30

    A Key objective of this program is to identify electrodes that will make it possible to significantly reduce the operating temperature of micro-SOFC and thin film-based SOFCs. Towards this end, efforts are directed towards: (a) identifying the key rate limiting steps which limit presently utilized electrodes from performing at reduced temperatures, as well as, (b) investigating the use of optical, as opposed to thermal energy, as a means for photocatalyzing electrode reactions and enabling reduced operating temperatures. During Phase I, the following objectives were achieved: (a) assembly and testing of our unique Microprobe Thin Film Characterization System; (b) fabrication of the model cathode materials system in thin film form by both PLD and ink jet printing; and (c) the successful configuration and testing of the model materials as cathodes in electrochemical cells. A further key objective (d) to test the potential of illumination in enhancing electrode performance was also achieved.

  15. MicroRNA profiles classify papillary renal cell carcinoma subtypes

    PubMed Central

    Wach, S; Nolte, E; Theil, A; Stöhr, C; T Rau, T; Hartmann, A; Ekici, A; Keck, B; Taubert, H; Wullich, B

    2013-01-01

    Background: Besides the conventional clear-cell renal cell carcinoma (ccRCC), papillary RCC (pRCC) is the second most common renal malignancy. Papillary RCCs can further be subdivided into two distinct subtypes. Although a clinical relevance of pRCC subtyping has been shown, little is known about the molecular characteristics of both pRCC subtypes. Methods: We performed microarray-based microRNA (miRNA) expression profiling of primary ccRCC and pRCC cases. A subset of miRNAs was identified and used to establish a classification model for ccRCC, pRCC types 1 and 2 and normal tissue. Furthermore, we performed gene set enrichment analysis with the predicted miRNA target genes. Results: Only five miRNAs (miR-145, -200c, -210, -502-3p and let-7c) were sufficient to identify the samples with high accuracy. In a collection of 111 tissue samples, 73.9% were classified correctly. An enrichment of miRNA target genes in the family of multidrug-resistance proteins was noted in all tumours. Several components of the Jak-STAT signalling pathway might be targets for miRNAs that define pRCC tumour subtypes. Conclusion: MicroRNAs are able to accurately classify RCC samples. Deregulated miRNAs might contribute to the high chemotherapy resistance of RCC. Furthermore, our results indicate that pRCC type 2 tumours could be dependent on oncogenic MYC signalling. PMID:23799849

  16. Parametric analyses of vapor-anode, multitube AMTEC cells for Pluto/Express mission

    NASA Astrophysics Data System (ADS)

    El-Genk, Mohamed S.; Tournier, Jean-Michel

    1998-01-01

    A detailed AMTEC Performance and Evaluation Analysis Model (APEAM) was used to evaluate the effects of various design changes on the performance of next-generation, Pluto/Express multitube cells. These changes were: using a CREARE condenser; changing the number of BASE tubes and the electrode length; using other electrode materials; using molybdenum (Mo) as the structural material on the hot side of the cell; and using reflective rhodium coatings in the low vapor pressure cavity of the cell. The present analyses utilized a PX-5A type cell, with a Mo circumferential radiation shield, and 7 BASE tubes with 29 mm-long electrodes. Analyses performed for an output load voltage of 3.5 V per cell showed that: (a) A stainless steel (SS) cell with improved electrodes (50% lower contact resistance than TiN, and an increased exchange current, B=200 A.K1/2/Pa.m2) could deliver 7.1 We with an efficiency of 19.5% (b) When Mo was substituted for the SS on the hot side of this cell, the electrical power output increased to 8.8 We and the cell efficiency increased to 20.2% (c) Using rhodium coatings in the Mo/SS cell increased the electrical power output to 9.7 We, and the peak efficiency by 2.3 points, to 22.5%.

  17. Micro space power system using MEMS fuel cell for nano-satellites

    NASA Astrophysics Data System (ADS)

    Lee, Jongkwang; Kim, Taegyu

    2014-08-01

    A micro space power system using micro fuel cell was developed for nano-satellites. The power system was fabricated using microelectromechanical system (MEMS) fabrication technologies. Polymer electrolyte membrane (PEM) fuel cell was selected in consideration of space environment. Sodium borohydride (NaBH4) was selected as a hydrogen source while hydrogen peroxide (H2O2) was selected as an oxygen source. The power system consists of a micro fuel cell, micro-reactor, micro-pump, and fuel cartridges. The micro fuel cell was fabricated on a light-weight and corrosion-resistant glass plates. The micro-reactor was used to generate hydrogen from NaBH4 alkaline solution via a catalytic hydrolysis reaction. All components such as micro-pump, fuel cartridges, and auxiliary battery were integrated for a complete power system. The storability of NaBH4 solution was evaluated at -25 °C and the performance of the micro power system was measured at various operating conditions. The power output of micro power system reasonably followed up the given electric load conditions.

  18. Transient response of nonlinear magneto-optic rotation in a paraffin-coated Rb vapor cell

    NASA Astrophysics Data System (ADS)

    Momeen, M. Ummal; Rangarajan, G.; Natarajan, Vasant

    2010-01-01

    We study resonant nonlinear magneto-optic rotation (NMOR) in a paraffin-coated Rb vapor cell as the magnetic field is swept. At low sweep rates, the nonlinear rotation appears as a narrow resonance signal with a linewidth of about “300 μG” (2π×420 Hz). At high sweep rates, the signal shows transient response with an oscillatory decay. The decay time constant is of order 100 ms. The behavior is different for transitions starting from the lower or the upper hyperfine level of the ground state because of optical pumping effects.

  19. Electromagnetically-induced transparency in Cs and Rb in the same vapor cell

    NASA Astrophysics Data System (ADS)

    Simons, Matt; Gordon, Joshua; Holloway, Christopher

    2016-05-01

    We demonstrate simultaneous electromagnetically-induced transparency (EIT) in both cesium and rubidium in the same vapor cell with coincident optical fields. Each atomic system can detect radio frequency (RF) field strengths through modification of the EIT signal. We show that these two systems can detect the same RF field strength simultaneously. This allows us to perform the same measurement in two effective ``laboratories,'' providing an immediate independent reference, which will lead to an SI-traceable RF E-field measurement. We examine the impact of coincident, simultaneous EIT on RF field metrology and the EIT signal.

  20. Efficient Collection of {sup 221}Fr into a Vapor Cell Magneto-optical Trap

    SciTech Connect

    Lu, Z.; Corwin, K.L.; Vogel, K.R.; Wieman, C.E. |; Dinneen, T.P.; Maddi, J.; Gould, H.

    1997-08-01

    We have efficiently loaded a vapor cell magneto-optical trap from an orthotropic source of {sup 221}Fr with a trapping efficiency of 56(10){percent}. A novel detection scheme allowed us to measure 900 trapped atoms with a signal to noise ratio of {approximately}60 in 1sec. We have measured the energies and the hyperfine constants of the 7 {sup 2}P{sub 1/2} and 7 {sup 2}P{sub 3/2} states. {copyright} {ital 1997} {ital The American Physical Society}

  1. Nanoparticle-coated micro-optofluidic ring resonator as a detector for microscale gas chromatographic vapor analysis

    NASA Astrophysics Data System (ADS)

    Scholten, K.; Collin, W. R.; Fan, X.; Zellers, E. T.

    2015-05-01

    A vapor sensor comprising a nanoparticle-coated microfabricated optofluidic ring resonator (μOFRR) is introduced. A multilayer film of polyether functionalized, thiolate-monolayer-protected gold nanoparticles (MPN) was solvent cast on the inner wall of the hollow cylindrical SiOx μOFRR resonator structure, and whispering gallery mode (WGM) resonances were generated with a 1550 nm tunable laser via an optical fiber taper. Reversible shifts in the WGM resonant wavelength upon vapor exposure were detected with a photodetector. The μOFRR chip was connected to a pair of upstream etched-Si chips containing PDMS-coated separation μcolumns and calibration curves were generated from the peak-area responses to five volatile organic compounds (VOCs). Calibration curves were linear, and the sensitivities reflected the influence of analyte volatility and analyte-MPN functional group affinity. Sorption-induced changes in film thickness apparently dominate over changes in the refractive index of the film as the determinant of responses for all VOCs. Peaks from the MPN-coated μOFRR were just 20-50% wider than those from a flame ionization detector for similar μcolumn separation conditions, reflecting the rapid response of the sensor for VOCs. The five VOCs were baseline separated in <1.67 min, with detection limits as low as 38 ng.

  2. Homojunction GaAs solar cells grown by close space vapor transport

    SciTech Connect

    Boucher, Jason W.; Ritenour, Andrew J.; Greenaway, Ann L.; Aloni, Shaul; Boettcher, Shannon W.

    2014-06-08

    We report on the first pn junction solar cells grown by homoepitaxy of GaAs using close space vapor transport (CSVT). Cells were grown both on commercial wafer substrates and on a CSVT absorber film, and had efficiencies reaching 8.1%, open circuit voltages reaching 909 mV, and internal quantum efficiency of 90%. The performance of these cells is partly limited by the electron diffusion lengths in the wafer substrates, as evidenced by the improved peak internal quantum efficiency in devices fabricated on a CSVT absorber film. Unoptimized highly-doped n-type emitters also limit the photocurrent, indicating that thinner emitters with reduced doping, and ultimately wider band gap window or surface passivation layers, are required to increase the efficiency.

  3. MicroRNA miR-125a controls hematopoietic stem cell number

    PubMed Central

    Guo, Shangqin; Lu, Jun; Schlanger, Rita; Zhang, Hao; Wang, Judy Y.; Fox, Michelle C.; Purton, Louise E.; Fleming, Heather H.; Cobb, Bradley; Merkenschlager, Matthias; Golub, Todd R.; Scadden, David T.

    2010-01-01

    MicroRNAs influence hematopoietic differentiation, but little is known about their effects on the stem cell state. Here, we report that the microRNA processing enzyme Dicer is essential for stem cell persistence in vivo and a specific microRNA, miR-125a, controls the size of the stem cell population by regulating hematopoietic stem/progenitor cell (HSPC) apoptosis. Conditional deletion of Dicer revealed an absolute dependence for the multipotent HSPC population in a cell-autonomous manner, with increased HSPC apoptosis in mutant animals. An evolutionarily conserved microRNA cluster containing miR-99b, let-7e, and miR-125a was preferentially expressed in long-term hematopoietic stem cells. MicroRNA miR-125a alone was capable of increasing the number of hematopoietic stem cells in vivo by more than 8-fold. This result was accomplished through a differentiation stage-specific reduction of apoptosis in immature hematopoietic progenitors, possibly through targeting multiple proapoptotic genes. Bak1 was directly down-regulated by miR-125a and expression of a 3′UTR-less Bak1 blocked miR-125a-induced hematopoietic expansion in vivo. These data demonstrate cell-state-specific regulation by microRNA and identify a unique microRNA functioning to regulate the stem cell pool size. PMID:20616003

  4. Single and multijunction space solar cells grown by organometallic vapor phase epitaxy (OM-VPE)

    SciTech Connect

    Borden, P.G.; Gregory, P.E.; Larue, R.A.; Ludowise, M.J.

    1982-08-01

    Organometallic Vapor Phase Epitaxy (OM-VPE) is a versatile technique for growing III-V compound semiconductor solar cells. It has good uniformity and morphology, control that allows growth of extremely thin layers, and is a technique readily automated. The vehicle for the present discussion is a metal interconnected cascade (MIC/sup 2/) solar cell that has achieved 16.6% AM0 and 22% AM3 efficiency (uncorrected for 14% grid coverage). These are the best results reported to date for a cascade solar cell. Features include a 9-layer epitaxial structure, the thinnest of which is less than 1000 thick, a high-efficiency 30% AlGaAs top cell only 1.5 microns thick, a GaAs bottom cell that has survived the 780/sup 0/C, 20-minute top cell growth, and process yields greater than 4 cm/sup 2/ per wafer. The paper describes the cell design requirements, how it was grown by OM-VPE, and performance results.

  5. Strong field radio-frequency measurements using Rydberg states in a vapor cell

    NASA Astrophysics Data System (ADS)

    Miller, Stephanie; Anderson, David; Raithel, Georg

    2016-05-01

    There has been a growing interest in using electromagnetically induced transparency with Rydberg atoms in a room-temperature vapor cell as an all-optical readout method for measuring microwave electric fields. We present results from RF-modulating the 60S1 / 2 and 58D5 / 2 Rydberg states of rubidium with 50 MHz and 100 MHz fields, respectively. Weak RF fields AC Stark-shifts the Rydberg states. As the field strength is increased, sidebands appear at even multiples of the driving frequency. When strong fields are applied, the nearby hydrogenic manifold begins to intersect with the shifted levels. Similar investigations have been performed in cesium. Due to the significant amount of state mixing and level structure, Floquet theory is required to describe the level shifts and mixing. By comparing the calculation with the experimental data, we obtain an absolute determination of the RF electric field reaching a maximum field of 296 V/m to within +/- 0 . 35 % . Additionally, we estimate the shielding of DC fields within the vapor cell.

  6. Analysis of long-time operation of micro-cogeneration unit with fuel cell

    NASA Astrophysics Data System (ADS)

    Patsch, Marek; Čaja, Alexander

    2015-05-01

    Micro-cogeneration is cogeneration with small performance, with maximal electric power up to 50 kWe. On the present, there are available small micro-cogeneration units with small electric performance, about 1 kWe, which are usable also in single family houses or flats. These micro-cogeneration units operate on principle of conventional combustion engine, Stirling engine, steam engine or fuel cell. Micro-cogeneration units with fuel cells are new progressive developing type of units for single family houses. Fuel cell is electrochemical device which by oxidation-reduction reaction turn directly chemical energy of fuel to electric power, secondary products are pure water and thermal energy. The aim of paper is measuring and evaluation of operation parameters of micro-cogeneration unit with fuel cell which uses natural gas as a fuel.

  7. Optical Measurements of Strong Microwave Fields with Rydberg Atoms in a Vapor Cell

    NASA Astrophysics Data System (ADS)

    Anderson, D. A.; Miller, S. A.; Raithel, G.; Gordon, J. A.; Butler, M. L.; Holloway, C. L.

    2016-03-01

    We present a spectral analysis of Rydberg atoms in strong microwave fields using electromagnetically induced transparency (EIT) as an all-optical readout. The measured spectroscopic response enables optical, atom-based electric-field measurements of high-power microwaves. In our experiments, microwaves are irradiated into a room-temperature rubidium vapor cell. The microwaves are tuned near the two-photon 65 D -66 D Rydberg transition and reach an electric-field strength of 230 V /m , about 20% of the microwave-ionization threshold of these atoms. A Floquet treatment is used to model the Rydberg-level energies and their excitation rates. We arrive at an empirical model for the field-strength distribution inside the spectroscopic cell that yields excellent overall agreement between the measured and calculated Rydberg EIT-Floquet spectra. Using spectral features in the Floquet maps, we achieve an absolute strong-field measurement precision of 6%.

  8. microRNAs in Cancer Cell Response to Ionizing Radiation

    PubMed Central

    Czochor, Jennifer R.

    2014-01-01

    Abstract Significance: microRNAs (miRNA) have been characterized as master regulators of the genome. As such, miRNAs are responsible for regulating almost every cellular pathway, including the DNA damage response (DDR) after ionizing radiation (IR). IR is a therapeutic tool that is used for the treatment of several types of cancer, yet the mechanism behind radiation response is not fully understood. Recent Advances: It has been demonstrated that IR can alter miRNA expression profiles, varying greatly from one cell type to the next. It is possible that this variation contributes to the range of tumor cell responsiveness that is observed after radiotherapy, especially considering the extensive role for miRNAs in regulating the DDR. In addition, individual miRNAs or miRNA families have been shown to play a multifaceted role in the DDR, regulating multiple members in a single pathway. Critical Issues: In this review, we will discuss the effects of radiation on miRNA expression as well as explore the function of miRNAs in regulating the cellular response to radiation-induced damage. We will discuss the importance of miRNA regulation at each stage of the DDR, including signal transduction, DNA damage sensing, cell cycle checkpoint activation, DNA double-strand break repair, and apoptosis. We will focus on emphasizing the importance of a single miRNA targeting several mediators within a pathway. Future Directions: miRNAs will continue to emerge as critical regulators of the DDR. Understanding the role of miRNAs in the response to IR will provide insights for improving the current standard therapy. Antioxid. Redox Signal. 21, 293–312. PMID:24206455

  9. Efficiency of photodesorption of Rb atoms collected on polymer organic film in vapor-cell

    NASA Astrophysics Data System (ADS)

    Atutov, S. N.; Chubakov, V. P.; Chubakov, P. A.; Plekhanov, A. I.

    2011-04-01

    The efficiency of photodesorption of Rb atoms previously collected on polymer organic film has been studied in detail. This study was carried out in a Pyrex glass cell of which the inner surface was covered with (poly)dimethylsiloxane (PDMS) film and illuminated by a powerful flash lamp. The desorption dynamic of the Rb atoms density in the cell caused by the illumination and percentage of desorbed atoms was studied by using of Rb resonance lamp and free running diode laser as sources of probing light. It was determined that 85 percent collected chemical active Rb atoms and stored during 16 s in the closed cell, 75 percent in the pumped cell can be desorbed by single flash of the lamp. The number of stored atoms decays with a characteristic time of 60 min in isolated cell and with a time 12.4 min in a pumped cell. We believe that this efficient method of collection and fast realization of atoms or molecules could be used for enhancement of sensitivity of existed sensors for the trace detection of various elements (including toxic or radioactive ones) which is important to environmental applications, medicine or in geology. The effect might help to construct an efficient light-driven atomic source for a magneto-optical trap in a case of extremely low vapor density or very weak flux of atoms, such as artificial radioactive alkali atoms.

  10. Analyses of Nb-1Zr/C-103, vapor anode, multi-tube AMTEC cells

    NASA Astrophysics Data System (ADS)

    King, Jeffrey C.; El-Genk, Mohamed S.

    2000-01-01

    A high performance, Nb-1Zr/C-103, vapor anode, multi-tube AMTEC cell design is presented. The cell measures 41.27 mm in diameter, is 125.3 mm high, and has eight BASE tubes connected electrically in series. The hot structure of the cell (hot plate, BASE tubes support plate, hot plenum wall, evaporator standoff, evaporator wick, and side wall facing the BASE tubes) is made of Nb-1Zr. The cold structure of the cell (condenser, interior cylindrical thermal radiation shield, the casing and the wick of the liquid sodium return artery, and side wall above the BASE tubes) is made of the stronger, lower thermal conductivity niobium alloy C-103. This cell, which weighs 163.4 g, could deliver 7.0 We at 17% efficiency and load voltage of 3.3 V, when using TiN BASE electrodes characterized by B=75 A.K1/2/m2.Pa and G=50 and assuming BASE/electrode contact resistance of 0.06 Ω-cm2 and leakage resistance of the BASE braze structure of 3 Ω. For these performance parameters and when the interior cylindrical C-103 thermal radiation shield is covered with low emissivity rhodium, the projected specific mass of the cell is 23.4 g/We. The BASE brazes and the evaporator temperatures were below the recommended limits of 1123 K and 1023 K, respectively. In addition, the temperature margin in the cell was at least + 20 K. When electrodes characterized by B=120 A.K1/2/m2.Pa and G=10 were used, the cell power increased to 8.38 We at 3.5 V and efficiency of 18.8%, for a cell specific mass of 19.7 g/We. Issues related to structure strength of the cell and the performance degradation of the BASE and electrodes are not addressed in this paper. .

  11. 40 CFR Table 5 to Subpart IIIii of... - Required Elements of Floor-Level Mercury Vapor Measurement and Cell Room Monitoring Plans

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Mercury Vapor Measurement and Cell Room Monitoring Plans 5 Table 5 to Subpart IIIII of Part 63 Protection... Hazardous Air Pollutants: Mercury Emissions From Mercury Cell Chlor-Alkali Plants Pt. 63, Subpt. IIIII... and Cell Room Monitoring Plans Your Floor-Level Mercury Vapor Measurement Plan required by §...

  12. 40 CFR Table 5 to Subpart IIIii of... - Required Elements of Floor-Level Mercury Vapor Measurement and Cell Room Monitoring Plans

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Mercury Vapor Measurement and Cell Room Monitoring Plans 5 Table 5 to Subpart IIIII of Part 63 Protection... Hazardous Air Pollutants: Mercury Emissions From Mercury Cell Chlor-Alkali Plants Pt. 63, Subpt. IIIII... and Cell Room Monitoring Plans Your Floor-Level Mercury Vapor Measurement Plan required by §...

  13. 40 CFR Table 5 to Subpart IIIii of... - Required Elements of Floor-Level Mercury Vapor Measurement and Cell Room Monitoring Plans

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Mercury Vapor Measurement and Cell Room Monitoring Plans 5 Table 5 to Subpart IIIII of Part 63 Protection... Hazardous Air Pollutants: Mercury Emissions From Mercury Cell Chlor-Alkali Plants Pt. 63, Subpt. IIIII... and Cell Room Monitoring Plans Your Floor-Level Mercury Vapor Measurement Plan required by §...

  14. 40 CFR Table 5 to Subpart IIIii of... - Required Elements of Floor-Level Mercury Vapor Measurement and Cell Room Monitoring Plans

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Mercury Vapor Measurement and Cell Room Monitoring Plans 5 Table 5 to Subpart IIIII of Part 63 Protection... Hazardous Air Pollutants: Mercury Emissions From Mercury Cell Chlor-Alkali Plants Pt. 63, Subpt. IIIII... and Cell Room Monitoring Plans Your Floor-Level Mercury Vapor Measurement Plan required by §...

  15. 40 CFR Table 5 to Subpart IIIii of... - Required Elements of Floor-Level Mercury Vapor Measurement and Cell Room Monitoring Plans

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Mercury Vapor Measurement and Cell Room Monitoring Plans 5 Table 5 to Subpart IIIII of Part 63 Protection... Hazardous Air Pollutants: Mercury Emissions From Mercury Cell Chlor-Alkali Plants Pt. 63, Subpt. IIIII... and Cell Room Monitoring Plans Your Floor-Level Mercury Vapor Measurement Plan required by §...

  16. Formaldehyde vapor produced from hexamethylenetetramine and pesticide: Simultaneous monitoring of formaldehyde and ozone in chamber experiments by flow-based hybrid micro-gas analyzer.

    PubMed

    Yanaga, Akira; Hozumi, Naruto; Ohira, Shin-Ichi; Hasegawa, Asako; Toda, Kei

    2016-02-01

    Simultaneous analysis of HCHO and O3 was performed by the developed flow analysis system to prove that HCHO vapor is produced from solid pesticide in the presence of O3. HCHO is produced in many ways, including as primary emissions from fuel combustion and in secondary production from anthropogenic and biogenic volatile organic compounds by photochemical reactions. In this work, HCHO production from pesticides was investigated for the first time. Commonly pesticide contains surfactant such as hexamethylenetetramine (HMT), which is a heterocyclic compound formed from six molecules of HCHO and four molecules of NH3. HMT can react with gaseous oxidants such as ozone (O3) to produce HCHO. In the present study, a flow analysis system was developed for simultaneous analysis of HCHO and O3, and this system was used to determine if solid pesticides produced HCHO vapor in the presence of O3. HMT or the pesticide jimandaisen, which contains mancozeb as the active ingradient and HMT as a stabilizer was placed at the bottom of a 20-L stainless steel chamber. Air in the chamber was monitored using the developed flow system. Analyte gases were collected into an absorbing solution by a honeycomb-patterned microchannel scrubber that was previously developed for a micro gas analysis system (μGAS). Subsequently, indigotrisulfonate, a blue dye, was added to the absorbing solution to detect O3, which discolored the solution. HCHO was detected after mixing with the Hantzsch reaction reagent. Both gases could be detected at concentrations ranging from parts per billion by volume (ppbv) to 1000 ppbv with good linearity. Both HMT and jimandaisen emitted large amount of HCHO in the presence of O3. PMID:26653496

  17. Synthesis and characterization of ZnO nano and micro structures grown by low temperature spray pyrolysis and vapor transport.

    PubMed

    Agouram, S; Bushiri, M J; Montenegro, D N; Reig, C; Martínez-Tomás, M C; Muñoz-Sanjosé, V

    2012-08-01

    In this work we present a systematic study of ZnO micro and nanostructures grown by spray pyrolysis (SP) and by physical vapour transport (PVT) on glass and c-sapphire substrates at low temperatures. Optimised growth conditions have allowed to obtain homogeneous ZnO nanolayers composed of quasi-spherical nanoparticles in the range 2 to 8 nm by spray pyrolysis, while by PVT the selected growth conditions allow to produce a wide variety of morphologies (tripods, grains, arrows and wires) of nano and microsize dimension. Grazing incidence X-ray diffraction, field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) and energy dispersive X-ray spectroscopy (EDX) were used as characterization techniques in the investigation of structural, morphological and compositional nature of these nanostructures in relation with the growth method. PMID:22962824

  18. Evaluation of E-Cigarette Liquid Vapor and Mainstream Cigarette Smoke after Direct Exposure of Primary Human Bronchial Epithelial Cells

    PubMed Central

    Scheffler, Stefanie; Dieken, Hauke; Krischenowski, Olaf; Förster, Christine; Branscheid, Detlev; Aufderheide, Michaela

    2015-01-01

    E-cigarettes are emerging products, often described as “reduced-risk” nicotine products or alternatives to combustible cigarettes. Many smokers switch to e-cigarettes to quit or significantly reduce smoking. However, no regulations for e-cigarettes are currently into force, so that the quality and safety of e-liquids is not necessarily guaranteed. We exposed primary human bronchial epithelial cells of two different donors to vapor of e-cigarette liquid with or without nicotine, vapor of the carrier substances propylene glycol and glycerol as well as to mainstream smoke of K3R4F research cigarettes. The exposure was done in a CULTEX® RFS compact module, allowing the exposure of the cells at the air-liquid interface. 24 h post-exposure, cell viability and oxidative stress levels in the cells were analyzed. We found toxicological effects of e-cigarette vapor and the pure carrier substances, whereas the nicotine concentration did not have an effect on the cell viability. The viability of mainstream smoke cigarette exposed cells was 4.5–8 times lower and the oxidative stress levels 4.5–5 times higher than those of e-cigarette vapor exposed cells, depending on the donor. Our experimental setup delivered reproducible data and thus provides the opportunity for routine testing of e-cigarette liquids to ensure safety and quality for the user. PMID:25856554

  19. MicroRNAs in diffuse large B-cell lymphoma

    PubMed Central

    NI, HUIYUN; TONG, RONG; ZOU, LINQING; SONG, GUOQI; CHO, WILLIAM C.

    2016-01-01

    The aberrant expression of microRNAs (miRs) has a significant impact on the biological characteristics of lymphocytes, and is important in the pathogenesis of diffuse large B-cell lymphoma (DLBCL). It has been demonstrated, using miR profiling and detecting distinct miR signatures, that certain miRs may accurately distinguish different subtypes and prognostic classifications of DLBCL, as well as distinguish DLBCL from other more indolent lymphomas, including follicular lymphoma. miRs are excellent biomarkers for cancer diagnosis and prognosis. In DLBCL, specific miR expression profiles in the tissues of patients are associated with prognosis and clinical outcome. Over the past decade, there has been substantial investigation concerning the pathogenetic, diagnostic and prognostic roles of miRs in DLBCL. The aim of the present review is to describe the aberrant expression of miRs in DLBCL, and the functions, potential clinical use and possible therapeutic targets of miRs in this disease. PMID:26893730

  20. MicroRNAs Dynamically Remodel Gastrointestinal Smooth Muscle Cells

    PubMed Central

    Park, Chanjae; Yan, Wei; Ward, Sean M.; Hwang, Sung Jin; Wu, Qiuxia; Hatton, William J.; Park, Jong Kun; Sanders, Kenton M.; Ro, Seungil

    2011-01-01

    Smooth muscle cells (SMCs) express a unique set of microRNAs (miRNAs) which regulate and maintain the differentiation state of SMCs. The goal of this study was to investigate the role of miRNAs during the development of gastrointestinal (GI) SMCs in a transgenic animal model. We generated SMC-specific Dicer null animals that express the reporter, green fluorescence protein, in a SMC-specific manner. SMC-specific knockout of Dicer prevented SMC miRNA biogenesis, causing dramatic changes in phenotype, function, and global gene expression in SMCs: the mutant mice developed severe dilation of the intestinal tract associated with the thinning and destruction of the smooth muscle (SM) layers; contractile motility in the mutant intestine was dramatically decreased; and SM contractile genes and transcriptional regulators were extensively down-regulated in the mutant SMCs. Profiling and bioinformatic analyses showed that SMC phenotype is regulated by a complex network of positive and negative feedback by SMC miRNAs, serum response factor (SRF), and other transcriptional factors. Taken together, our data suggest that SMC miRNAs are required for the development and survival of SMCs in the GI tract. PMID:21533178

  1. SMART FUEL CELL OPERATED RESIDENTIAL MICRO-GRID COMMUNITY

    SciTech Connect

    Dr. Mohammad S. Alam University of South Alabama ECE Department, EEB 75 Mobile, AL 36688-0002 Phone: 251-460-6117 Fax: 251-460-6028

    2005-04-13

    To build on the work of year one by expanding the smart control algorithm developed to a micro-grid of ten houses; to perform a cost analysis; to evaluate alternate energy sources; to study system reliability; to develop the energy management algorithm, and to perform micro-grid software and hardware simulations.

  2. Laser light routing in an elongated micromachined vapor cell with diffraction gratings for atomic clock applications

    PubMed Central

    Chutani, Ravinder; Maurice, Vincent; Passilly, Nicolas; Gorecki, Christophe; Boudot, Rodolphe; Abdel Hafiz, Moustafa; Abbé, Philippe; Galliou, Serge; Rauch, Jean-Yves; de Clercq, Emeric

    2015-01-01

    This paper reports on an original architecture of microfabricated alkali vapor cell designed for miniature atomic clocks. The cell combines diffraction gratings with anisotropically etched single-crystalline silicon sidewalls to route a normally-incident beam in a cavity oriented along the substrate plane. Gratings have been specifically designed to diffract circularly polarized light in the first order, the latter having an angle of diffraction matching the (111) sidewalls orientation. Then, the length of the cavity where light interacts with alkali atoms can be extended. We demonstrate that a longer cell allows to reduce the beam diameter, while preserving the clock performances. As the cavity depth and the beam diameter are reduced, collimation can be performed in a tighter space. This solution relaxes the constraints on the device packaging and is suitable for wafer-level assembly. Several cells have been fabricated and characterized in a clock setup using coherent population trapping spectroscopy. The measured signals exhibit null power linewidths down to 2.23 kHz and high transmission contrasts up to 17%. A high contrast-to-linewidth ratio is found at a linewidth of 4.17 kHz and a contrast of 5.2% in a 7-mm-long cell despite a beam diameter reduced to 600 μm. PMID:26365754

  3. Laser light routing in an elongated micromachined vapor cell with diffraction gratings for atomic clock applications.

    PubMed

    Chutani, Ravinder; Maurice, Vincent; Passilly, Nicolas; Gorecki, Christophe; Boudot, Rodolphe; Abdel Hafiz, Moustafa; Abbé, Philippe; Galliou, Serge; Rauch, Jean-Yves; de Clercq, Emeric

    2015-01-01

    This paper reports on an original architecture of microfabricated alkali vapor cell designed for miniature atomic clocks. The cell combines diffraction gratings with anisotropically etched single-crystalline silicon sidewalls to route a normally-incident beam in a cavity oriented along the substrate plane. Gratings have been specifically designed to diffract circularly polarized light in the first order, the latter having an angle of diffraction matching the (111) sidewalls orientation. Then, the length of the cavity where light interacts with alkali atoms can be extended. We demonstrate that a longer cell allows to reduce the beam diameter, while preserving the clock performances. As the cavity depth and the beam diameter are reduced, collimation can be performed in a tighter space. This solution relaxes the constraints on the device packaging and is suitable for wafer-level assembly. Several cells have been fabricated and characterized in a clock setup using coherent population trapping spectroscopy. The measured signals exhibit null power linewidths down to 2.23 kHz and high transmission contrasts up to 17%. A high contrast-to-linewidth ratio is found at a linewidth of 4.17 kHz and a contrast of 5.2% in a 7-mm-long cell despite a beam diameter reduced to 600 μm. PMID:26365754

  4. Laser light routing in an elongated micromachined vapor cell with diffraction gratings for atomic clock applications

    NASA Astrophysics Data System (ADS)

    Chutani, Ravinder; Maurice, Vincent; Passilly, Nicolas; Gorecki, Christophe; Boudot, Rodolphe; Abdel Hafiz, Moustafa; Abbé, Philippe; Galliou, Serge; Rauch, Jean-Yves; de Clercq, Emeric

    2015-09-01

    This paper reports on an original architecture of microfabricated alkali vapor cell designed for miniature atomic clocks. The cell combines diffraction gratings with anisotropically etched single-crystalline silicon sidewalls to route a normally-incident beam in a cavity oriented along the substrate plane. Gratings have been specifically designed to diffract circularly polarized light in the first order, the latter having an angle of diffraction matching the (111) sidewalls orientation. Then, the length of the cavity where light interacts with alkali atoms can be extended. We demonstrate that a longer cell allows to reduce the beam diameter, while preserving the clock performances. As the cavity depth and the beam diameter are reduced, collimation can be performed in a tighter space. This solution relaxes the constraints on the device packaging and is suitable for wafer-level assembly. Several cells have been fabricated and characterized in a clock setup using coherent population trapping spectroscopy. The measured signals exhibit null power linewidths down to 2.23 kHz and high transmission contrasts up to 17%. A high contrast-to-linewidth ratio is found at a linewidth of 4.17 kHz and a contrast of 5.2% in a 7-mm-long cell despite a beam diameter reduced to 600 μm.

  5. Chromium vaporization from mechanically deformed pre-coated interconnects in Solid Oxide Fuel Cells

    NASA Astrophysics Data System (ADS)

    Falk-Windisch, Hannes; Sattari, Mohammad; Svensson, Jan-Erik; Froitzheim, Jan

    2015-11-01

    Cathode poisoning, associated with Cr evaporation from interconnect material, is one of the most important degradation mechanisms in Solid Oxide Fuel Cells when Cr2O3-forming steels are used as the interconnect material. Coating these steels with a thin Co layer has proven to decrease Cr vaporization. To reduce production costs, it is suggested that thin metallic PVD coatings be applied to each steel strip before pressing the material into interconnect shape. This process would enable high volume production without the need for an extra post-coating step. However, when the pre-coated material is mechanically deformed, cracks may form and lower the quality of the coating. In the present study, Chromium volatilization is measured in an air-3% H2O environment at 850 °C for 336 h. Three materials coated with 600 nm Co are investigated and compared to an uncoated material. The effect of deformation is investigated on real interconnects. Microscopy observations reveal the presence of cracks in the order of several μm on the deformed pre-coated steel. However, upon exposure, the cracks can heal and form a continuous surface oxide rich in Co and Mn. As an effect of the rapid healing, no increase in Cr vaporization is measured for the pre-coated material.

  6. Widefield microwave imaging in alkali vapor cells with sub-100 μm resolution

    NASA Astrophysics Data System (ADS)

    Horsley, Andrew; Du, Guan-Xiang; Treutlein, Philipp

    2015-11-01

    We report on widefield microwave vector field imaging with sub-100 μ {{m}} resolution using a microfabricated alkali vapor cell. The setup can additionally image dc magnetic fields, and can be configured to image microwave electric fields. Our camera-based widefield imaging system records 2D images with a 6 × 6 mm2 field of view at a rate of 10 Hz. It provides up to 50 μ {{m}} spatial resolution, and allows imaging of fields as close as 150 μ {{m}} above structures, through the use of thin external cell walls. This is crucial in allowing us to take practical advantage of the high spatial resolution, as feature sizes in near-fields are on the order of the distance from their source, and represent an order of magnitude improvement in surface-feature resolution compared to previous vapor cell experiments. We present microwave and dc magnetic field images above a selection of devices, demonstrating a microwave sensitivity of 1.4 μ {{T}} {{Hz}}-1/2 per 50× 50× 140 μ {{{m}}}3 voxel, at present limited by the speed of our camera system. Since we image 120 × 120 voxels in parallel, a single scanned sensor would require a sensitivity of at least 12 {nT} {{Hz}}-1/2 to produce images with the same sensitivity. Our technique could prove transformative in the design, characterization, and debugging of microwave devices, as there are currently no satisfactory established microwave imaging techniques. Moreover, it could find applications in medical imaging.

  7. Micro-plasma Luminescence And Signal Noise Used To Solar Cells Defects Diagnostic

    NASA Astrophysics Data System (ADS)

    Jiri, Vanek; Pavel, Koktavy; Jan, Dolensky; Ales, Vesely; Zdenek, Chobola; Petr, Paracka

    2009-04-01

    This work deals with the usage of signal noise and micro-plasmas luminescence for solar cells diagnostic. When high electric field is applied to PN junction of solar cell with some technological imperfections it produces in tiny areas of enhanced impact ionization called micro-plasmas which could lead to deterioration in quality or destruction of PN junction. On this account it is possible to use methods which indicate presence of micro-plasma in junction and enable quality and quantitative description of tested cells.

  8. MicroRNAs in Neural Stem Cells and Neurogenesis

    PubMed Central

    Kawahara, Hironori; Imai, Takao; Okano, Hideyuki

    2012-01-01

    MicroRNA (miRNA) is a type of short-length (~22 nt) non-coding RNA. Most miRNAs are transcribed by RNA polymerase II and processed by Drosha-DGCR8 and Dicer complexes in the cropping and dicing steps, respectively. miRNAs are exported by exportin-5 from the nucleus to the cytoplasm after cropping. Trimmed mature miRNA is loaded and targets mRNA at the 3′ or 5′ untranslated region (UTR) by recognition of base-pairing in the miRNA-loaded RISC, where it is involved in gene silencing including translational repression and/or degradation along with deadenylation. Recent studies have shown that miRNA participates in various biological functions including cell fate decision, developmental timing regulation, apoptosis, and tumorigenesis. Analyses of miRNA expression profiles have demonstrated tissue- and stage-specific miRNAs including the let-7 family, miR-124, and miR-9, which regulate the differentiation of embryonic stem cells and/or neurogenesis. This review focuses on RNA-binding protein-mediated miRNA biogenesis during neurogenesis. These miRNA biogenesis-relating proteins have also been linked to human diseases because their mutations can cause several nervous system disorders. Moreover, defects in core proteins involved in miRNA biogenesis including Drosha, DGCR8, and Dicer promote tumorigenesis. Thus, the study of not only mature miRNA function but also miRNA biogenesis steps is likely to be important. PMID:22416227

  9. Numerical characterization of micro-cell UO2sbnd Mo pellet for enhanced thermal performance

    NASA Astrophysics Data System (ADS)

    Lee, Heung Soo; Kim, Dong-Joo; Kim, Sun Woo; Yang, Jae Ho; Koo, Yang-Hyun; Kim, Dong Rip

    2016-08-01

    Metallic micro-cell UO2 pellet with high thermal conductivity has received attention as a promising accident-tolerant fuel. Although experimental demonstrations have been successful, studies on the potency of current metallic micro-cell UO2 fuels for further enhancement of thermal performance are lacking. Here, we numerically investigated the thermal conductivities of micro-cell UO2sbnd Mo pellets in terms of the amount of Mo content, the unit cell size, and the aspect ratio of the micro-cells. The results showed good agreement with experimental measurements, and more importantly, indicated the importance of optimizing the unit cell geometries of the micro-cell pellets for greater increases in thermal conductivity. Consequently, the micro-cell UO2sbnd Mo pellets (5 vol% Mo) with modified geometries increased the thermal conductivity of the current UO2 pellets by about 2.5 times, and lowered the temperature gradient within the pellets by 62.9% under a linear heat generation rate of 200 W/cm.

  10. Transcriptome sequencing reveals e-cigarette vapor and mainstream-smoke from tobacco cigarettes activate different gene expression profiles in human bronchial epithelial cells.

    PubMed

    Shen, Yifei; Wolkowicz, Michael J; Kotova, Tatyana; Fan, Lonjiang; Timko, Michael P

    2016-01-01

    Electronic cigarettes (e-cigarettes) generate an aerosol vapor (e-vapor) thought to represent a less risky alternative to main stream smoke (MSS) of conventional tobacco cigarettes. RNA-seq analysis was used to examine the transcriptomes of differentiated human bronchial epithelial (HBE) cells exposed to air, MSS from 1R5F tobacco reference cigarettes, and e-vapor with and without added nicotine in an in vitro air-liquid interface model for cellular exposure. Our results indicate that while e-vapor does not elicit many of the cell toxicity responses observed in MSS-exposed HBE cells, e-vapor exposure is not benign, but elicits discrete transcriptomic signatures with and without added nicotine. Among the cellular pathways with the most significantly enriched gene expression following e-vapor exposure are the phospholipid and fatty acid triacylglycerol metabolism pathways. Our data suggest that alterations in cellular glycerophopholipid biosynthesis are an important consequences of e-vapor exposure. Moreover, the presence of nicotine in e-vapor elicits a cellular response distinct from e-vapor alone including alterations of cytochrome P450 function, retinoid metabolism, and nicotine catabolism. These studies establish a baseline for future analysis of e-vapor and e-vapor additives that will better inform the FDA and other governmental bodies in discussions of the risks and future regulation of these products. PMID:27041137

  11. Transcriptome sequencing reveals e-cigarette vapor and mainstream-smoke from tobacco cigarettes activate different gene expression profiles in human bronchial epithelial cells

    PubMed Central

    Shen, Yifei; Wolkowicz, Michael J.; Kotova, Tatyana; Fan, Lonjiang; Timko, Michael P.

    2016-01-01

    Electronic cigarettes (e-cigarettes) generate an aerosol vapor (e-vapor) thought to represent a less risky alternative to main stream smoke (MSS) of conventional tobacco cigarettes. RNA-seq analysis was used to examine the transcriptomes of differentiated human bronchial epithelial (HBE) cells exposed to air, MSS from 1R5F tobacco reference cigarettes, and e-vapor with and without added nicotine in an in vitro air-liquid interface model for cellular exposure. Our results indicate that while e-vapor does not elicit many of the cell toxicity responses observed in MSS-exposed HBE cells, e-vapor exposure is not benign, but elicits discrete transcriptomic signatures with and without added nicotine. Among the cellular pathways with the most significantly enriched gene expression following e-vapor exposure are the phospholipid and fatty acid triacylglycerol metabolism pathways. Our data suggest that alterations in cellular glycerophopholipid biosynthesis are an important consequences of e-vapor exposure. Moreover, the presence of nicotine in e-vapor elicits a cellular response distinct from e-vapor alone including alterations of cytochrome P450 function, retinoid metabolism, and nicotine catabolism. These studies establish a baseline for future analysis of e-vapor and e-vapor additives that will better inform the FDA and other governmental bodies in discussions of the risks and future regulation of these products. PMID:27041137

  12. Role of microRNAs in islet beta-cell compensation and failure during diabetes.

    PubMed

    Plaisance, Valérie; Waeber, Gérard; Regazzi, Romano; Abderrahmani, Amar

    2014-01-01

    Pancreatic beta-cell function and mass are markedly adaptive to compensate for the changes in insulin requirement observed during several situations such as pregnancy, obesity, glucocorticoids excess, or administration. This requires a beta-cell compensation which is achieved through a gain of beta-cell mass and function. Elucidating the physiological mechanisms that promote functional beta-cell mass expansion and that protect cells against death, is a key therapeutic target for diabetes. In this respect, several recent studies have emphasized the instrumental role of microRNAs in the control of beta-cell function. MicroRNAs are negative regulators of gene expression, and are pivotal for the control of beta-cell proliferation, function, and survival. On the one hand, changes in specific microRNA levels have been associated with beta-cell compensation and are triggered by hormones or bioactive peptides that promote beta-cell survival and function. Conversely, modifications in the expression of other specific microRNAs contribute to beta-cell dysfunction and death elicited by diabetogenic factors including, cytokines, chronic hyperlipidemia, hyperglycemia, and oxidized LDL. This review underlines the importance of targeting the microRNA network for future innovative therapies aiming at preventing the beta-cell decline in diabetes. PMID:24734255

  13. Role of MicroRNAs in Islet Beta-Cell Compensation and Failure during Diabetes

    PubMed Central

    Plaisance, Valérie; Waeber, Gérard

    2014-01-01

    Pancreatic beta-cell function and mass are markedly adaptive to compensate for the changes in insulin requirement observed during several situations such as pregnancy, obesity, glucocorticoids excess, or administration. This requires a beta-cell compensation which is achieved through a gain of beta-cell mass and function. Elucidating the physiological mechanisms that promote functional beta-cell mass expansion and that protect cells against death, is a key therapeutic target for diabetes. In this respect, several recent studies have emphasized the instrumental role of microRNAs in the control of beta-cell function. MicroRNAs are negative regulators of gene expression, and are pivotal for the control of beta-cell proliferation, function, and survival. On the one hand, changes in specific microRNA levels have been associated with beta-cell compensation and are triggered by hormones or bioactive peptides that promote beta-cell survival and function. Conversely, modifications in the expression of other specific microRNAs contribute to beta-cell dysfunction and death elicited by diabetogenic factors including, cytokines, chronic hyperlipidemia, hyperglycemia, and oxidized LDL. This review underlines the importance of targeting the microRNA network for future innovative therapies aiming at preventing the beta-cell decline in diabetes. PMID:24734255

  14. Suppression of vapor cell temperature error for spin-exchange-relaxation-free magnetometer

    SciTech Connect

    Lu, Jixi Qian, Zheng; Fang, Jiancheng; Quan, Wei

    2015-08-15

    This paper presents a method to reduce the vapor cell temperature error of the spin-exchange-relaxation-free (SERF) magnetometer. The fluctuation of cell temperature can induce variations of the optical rotation angle, resulting in a scale factor error of the SERF magnetometer. In order to suppress this error, we employ the variation of the probe beam absorption to offset the variation of the optical rotation angle. The theoretical discussion of our method indicates that the scale factor error introduced by the fluctuation of the cell temperature could be suppressed by setting the optical depth close to one. In our experiment, we adjust the probe frequency to obtain various optical depths and then measure the variation of scale factor with respect to the corresponding cell temperature changes. Our experimental results show a good agreement with our theoretical analysis. Under our experimental condition, the error has been reduced significantly compared with those when the probe wavelength is adjusted to maximize the probe signal. The cost of this method is the reduction of the scale factor of the magnetometer. However, according to our analysis, it only has minor effect on the sensitivity under proper operating parameters.

  15. Frequency-tunable microwave field detection in an atomic vapor cell

    NASA Astrophysics Data System (ADS)

    Horsley, Andrew; Treutlein, Philipp

    2016-05-01

    We use an atomic vapor cell as a frequency tunable microwave field detector operating at frequencies from GHz to tens of GHz. We detect microwave magnetic fields from 2.3 GHz to 26.4 GHz, and measure the amplitude of the σ+ component of an 18 GHz microwave field. Our proof-of-principle demonstration represents a four orders of magnitude extension of the frequency tunable range of atomic magnetometers from their previous dc to several MHz range. When integrated with a high-resolution microwave imaging system [Horsley et al., New J. Phys. 17, 112002 (2015)], this will allow for the complete reconstruction of the vector components of a microwave magnetic field and the relative phase between them. Potential applications include near-field characterisation of microwave circuitry and devices, and medical microwave sensing and imaging.

  16. The DARPA HUMS program: revolutionizing magnetic field sensors using multiferroic materials and atomic gas vapor cells

    NASA Astrophysics Data System (ADS)

    Coblenz, William S.; Wartenberg, Scott A.

    2012-06-01

    The Heterostructural Uncooled Magnetic Sensors (HUMS) program sponsored by the Defense Advanced Research Projects Agency (DARPA/DSO) is focused on developing magnetic field sensors that operate at room temperature with an ultra-sensitivity to enable applications such as through-wall imaging, perimeter fences, tagging/tracking, and other man-portable operations. Four teams of researchers are participating in the program, with Virginia Tech and University of Maryland leading multiferroic heterostructural materials development and Princeton University and the National Institute of Standards and Technology (NIST) leading atomic vapor cell development. Leveraging the strengths of these two technologies, each team has made advancements towards the program goal of ground-breaking sensitivity, reduced noise, and portability while operating under room temperature conditions. This paper summarizes the program's achievements so far and highlights the accomplishments made by each team.

  17. Theoretical description of transverse measurements of polarization in optically-pumped Rb vapor cells

    NASA Astrophysics Data System (ADS)

    Dreiling, Joan; Tupa, Dale; Norrgard, Eric; Gay, Timothy

    2012-06-01

    In optical pumping of alkali-metal vapors, the polarization of the atoms is typically determined by probing along the entire length of the pumping beam, resulting in an averaged value of polarization over the length of the cell. Such measurements do not give any information about spatial variations of the polarization along the pump beam axis. Using a D1 probe beam oriented perpendicular to the pumping beam, we have demonstrated a heuristic method for determining the polarization along the pump beam's axis. Adapting a previously developed theory [1], we provide an analysis of the experiment which explains why this method works. The model includes the effects of Rb density, buffer gas pressure, and pump detuning. [4pt] [1] E.B. Norrgard, D. Tupa, J.M. Dreiling, and T.J. Gay, Phys. Rev. A 82, 033408 (2010).

  18. MicroRNA-regulated pathways in hematological malignancies: how to avoid cells playing out of tune.

    PubMed

    Fatica, Alessandro; Fazi, Francesco

    2013-01-01

    The coordinated expression and interplay among lineage specific transcription factors and microRNAs contribute to the regulation of gene expression and determination of cell specificity. In hematopoietic stem cells (HSCs), unique combinations of transcription factors largely control growth and maturation of different blood cell lineages through cooperative regulation of specific target genes. MicroRNAs provide an additional level of control beyond transcription factors. By acting as regulators of crucial lineage-specific genetic programs, microRNAs direct early multipotential progenitor cells to adopt a certain cell fate program. Thus, alteration of specific microRNA levels may affect proliferation, differentiation and genetic stability of HSCs, contributing to the onset of myeloproliferative disorders and leukemia. The major aim of this review is to highlight the critical role of microRNA-regulated pathways during the establishment and progression of hematological malignancies, with a particular attention to leukemia, lymphomas and myelodysplastic syndromes. This will give us the opportunity to discuss the potential use of microRNA-based therapeutic approaches in these diseases. MicroRNAs are indeed emerging as relevant tools to improve the efficacy of currently used therapeutic protocols. PMID:24145746

  19. MicroRNA Expression and Regulation in Human Ovarian Carcinoma Cells by Luteinizing Hormone

    PubMed Central

    Cui, Juan; Eldredge, Joanna B.; Xu, Ying; Puett, David

    2011-01-01

    Background MicroRNAs have been widely-studied with regard to their aberrant expression and high correlation with tumorigenesis and progression in various solid tumors. With the major goal of assessing gonadotropin (luteinizing hormone, LH) contributions to LH receptor (LHR)-positive ovarian cancer cells, we have conducted a genome-wide transcriptomic analysis on human epithelial ovarian cancer cells to identify the microRNA-associated cellular response to LH-mediated activation of LHR. Methods Human ovarian cancer cells (SKOV3) were chosen as negative control (LHR−) and stably transfected to express functional LHR (LHR+), followed by incubation with LH (0–20 h). At different times of LH-mediated activation of LHR the cancer cells were analyzed by a high-density Ovarian Cancer Disease-Specific-Array (DSA, ALMAC™), which profiled ∼100,000 transcripts with ∼400 non-coding microRNAs. Findings In total, 65 microRNAs were identified to exhibit differential expression in either LHR expressing SKOV3 cells or LH-treated cells, a few of which have been found in the genomic fragile regions that are associated with abnormal deletion or amplification in cancer, such as miR-21, miR-101-1, miR-210 and miR-301a. By incorporating the dramatic expression changes observed in mRNAs, strong microRNA/mRNA regulatory pairs were predicted through statistical analyses coupled with collective computational prediction. The role of each microRNA was then determined through a functional analysis based on the highly-confident microRNA/mRNA pairs. Conclusion The overall impact on the transcriptome-level expression indicates that LH may regulate apoptosis and cell growth of LHR+ SKOV3 cells, particularly by reducing cancer cell proliferation, with some microRNAs involved in regulatory roles. PMID:21765906

  20. Life on magnets: stem cell networking on micro-magnet arrays.

    PubMed

    Zablotskii, Vitalii; Dejneka, Alexandr; Kubinová, Šárka; Le-Roy, Damien; Dumas-Bouchiat, Frédéric; Givord, Dominique; Dempsey, Nora M; Syková, Eva

    2013-01-01

    Interactions between a micro-magnet array and living cells may guide the establishment of cell networks due to the cellular response to a magnetic field. To manipulate mesenchymal stem cells free of magnetic nanoparticles by a high magnetic field gradient, we used high quality micro-patterned NdFeB films around which the stray field's value and direction drastically change across the cell body. Such micro-magnet arrays coated with parylene produce high magnetic field gradients that affect the cells in two main ways: i) causing cell migration and adherence to a covered magnetic surface and ii) elongating the cells in the directions parallel to the edges of the micro-magnet. To explain these effects, three putative mechanisms that incorporate both physical and biological factors influencing the cells are suggested. It is shown that the static high magnetic field gradient generated by the micro-magnet arrays are capable of assisting cell migration to those areas with the strongest magnetic field gradient, thereby allowing the build up of tunable interconnected stem cell networks, which is an elegant route for tissue engineering and regenerative medicine. PMID:23936425

  1. Bioeffects due to acoustic droplet vaporization

    NASA Astrophysics Data System (ADS)

    Bull, Joseph

    2015-11-01

    Encapsulated micro- and nano-droplets can be vaporized via ultrasound, a process termed acoustic droplet vaporization. Our interest is primarily motivated by a developmental gas embolotherapy technique for cancer treatment. In this methodology, infarction of tumors is induced by selectively formed vascular gas bubbles that arise from the acoustic vaporization of vascular microdroplets. Additionally, the microdroplets may be used as vehicles for localized drug delivery, with or without flow occlusion. In this talk, we examine the dynamics of acoustic droplet vaporization through experiments and theoretical/computational fluid mechanics models, and investigate the bioeffects of acoustic droplet vaporization on endothelial cells and in vivo. Early timescale vaporization events, including phase change, are directly visualized using ultra-high speed imaging, and the influence of acoustic parameters on droplet/bubble dynamics is discussed. Acoustic and fluid mechanics parameters affecting the severity of endothelial cell bioeffects are explored. These findings suggest parameter spaces for which bioeffects may be reduced or enhanced, depending on the objective of the therapy. This work was supported by NIH grant R01EB006476.

  2. Spectroscopy in an extremely thin vapor cell: Comparing the cell-length dependence in fluorescence and in absorption techniques

    NASA Astrophysics Data System (ADS)

    Sarkisyan, D.; Varzhapetyan, T.; Sarkisyan, A.; Malakyan, Yu.; Papoyan, A.; Lezama, A.; Bloch, D.; Ducloy, M.

    2004-06-01

    We compare the behavior of absorption and of resonance fluorescence spectra in an extremely thin Rb vapor cell as a function of the ratio of L/λ , with L the cell thickness (L˜150 1800 nm) and λ the wavelength of the Rb D2 line (λ=780 mn) . The Dicke-type coherent narrowing [

    G. Dutier et al., Europhys. Lett. 63, 35 (2003)
    ] is observed only in transmission measurements, in the linear regime, with its typical collapse and revival, which reaches a maximum for L= (2n+1) λ/2 ( n integer). It is shown not to appear in fluorescence, whose behavior-amplitude, and spectral width, is more monotonic with L . Conversely, at high-intensity, the sub-Doppler saturation effects are shown to be the most visible in transmission around L=nλ .

  3. Search for MicroRNAs Expressed by Intracellular Bacterial Pathogens in Infected Mammalian Cells

    PubMed Central

    Furuse, Yuki; Finethy, Ryan; Saka, Hector A.; Xet-Mull, Ana M.; Sisk, Dana M.; Smith, Kristen L. Jurcic; Lee, Sunhee; Coers, Jörn; Valdivia, Raphael H.; Tobin, David M.; Cullen, Bryan R.

    2014-01-01

    MicroRNAs are expressed by all multicellular organisms and play a critical role as post-transcriptional regulators of gene expression. Moreover, different microRNA species are known to influence the progression of a range of different diseases, including cancer and microbial infections. A number of different human viruses also encode microRNAs that can attenuate cellular innate immune responses and promote viral replication, and a fungal pathogen that infects plants has recently been shown to express microRNAs in infected cells that repress host cell immune responses and promote fungal pathogenesis. Here, we have used deep sequencing of total expressed small RNAs, as well as small RNAs associated with the cellular RNA-induced silencing complex RISC, to search for microRNAs that are potentially expressed by intracellular bacterial pathogens and translocated into infected animal cells. In the case of Legionella and Chlamydia and the two mycobacterial species M. smegmatis and M. tuberculosis, we failed to detect any bacterial small RNAs that had the characteristics expected for authentic microRNAs, although large numbers of small RNAs of bacterial origin could be recovered. However, a third mycobacterial species, M. marinum, did express an ∼23-nt small RNA that was bound by RISC and derived from an RNA stem-loop with the characteristics expected for a pre-microRNA. While intracellular expression of this candidate bacterial microRNA was too low to effectively repress target mRNA species in infected cultured cells in vitro, artificial overexpression of this potential bacterial pre-microRNA did result in the efficient repression of a target mRNA. This bacterial small RNA therefore represents the first candidate microRNA of bacterial origin. PMID:25184567

  4. Mechanical modelling of confined cell migration across constricted-curved micro-channels.

    PubMed

    Allena, R

    2014-09-01

    Confined migration is a crucial phenomenon during embryogenesis, immune response and cancer. Here, a two-dimensional finite element model of a HeLa cell migrating across constricted-curved micro-channels is proposed. The cell is modelled as a continuum with embedded cytoplasm and nucleus, which are described by standard Maxwell viscoelastic models. The decomposition of the deformation gradient is employed to define the cyclic active strains of protrusion and contraction, which are synchronized with the adhesion forces between the cell and the substrate. The micro-channels are represented by two rigid walls and exert an additional viscous force on the cell boundaries. Five configurations have been tested: 1) top constriction, 2) top-bottom constriction, 3) shifted top-bottom constriction, 4) embedded obstacle and 5) bending micro-channel. Additionally, for the first four micro-channels both sub-cellular and sub-nuclear constrictions have been obtained, while for the fifth micro-channel three types of bending have been investigated ('curved', 'sharp' and 'sharper'). For each configuration, several parameters such as the cell behaviour, the covered distance, the migration velocity, the ratio between the cell and the nucleus area as well as the cell-substrate and cell-channel surfaces forces have been evaluated. The results show once more the fundamental role played by mechanics of both the cell and the environment. PMID:25831860

  5. Pentacene/K12 solar cells formed by organic vapor phase deposition

    NASA Astrophysics Data System (ADS)

    Axmann, Sebastian; Brast, Michael; Pandey, Ajay Kumar; Burn, Paul; Meredith, Paul; Heuken, Michael; Vescan, Andrei; Kalisch, Holger

    2014-01-01

    This study reports on an organic solar cell structure utilizing K12 as a new low-temperature processable small-molecule acceptor material. Pentacene (PEN) and K12 were deposited onto indium tin oxide by means of organic vapor phase deposition (OVPD) as bilayer solar cells. The resulting solar cell was characterized electrically by current density-voltage (J-V) measurements and optically by photocurrent and reflectivity measurements. The J-V characteristic under AM 1.5 illumination indicates a short-circuit current of 0.45 mA/cm2 (Jsc), a fill factor of 38% (FF), and an open-circuit (Voc) voltage of 0.71 V. Current generation is found to predominantly occur in the K12 layer, although strong light absorption in the PEN layer is detected. We suggest that either a dipole shift between the layers or the fission of singlet excitons in the PEN layer leads to this observation. Although the efficiency of the device is low in combination with PEN, our experiment successfully demonstrates the use of K12 as a low-temperature acceptor material in OVPD processes.

  6. Amorphous Carbon Deposited by a Novel Aerosol-Assisted Chemical Vapor Deposition for Photovoltaic Solar Cells

    NASA Astrophysics Data System (ADS)

    Ahmad, Nurfadzilah; Kamaruzzaman, Dayana; Rusop, Mohamad

    2012-06-01

    Amorphous carbon (a-C) solar cells were successfully prepared using a novel and self-designed aerosol-assisted chemical vapor deposition (AACVD) method using camphor oil as a precursor. The fabricated solar cell with the configuration of Au/p-C/n-Si/Au achieved an efficiency of 0.008% with a fill factor of 0.15 for the device deposited at 0.5 h. The current-voltage (I-V) graph emphasized on the linear graph (ohmic) for the a-C thin films, whereas for the p-n device structure, a rectifying curve was obtained. The rectifying curves signify the heterojunction between the p-type a-C film and the n-Si substrate and designate the generation of electron-hole pair of the samples under illumination. Photoresponse characteristics of the deposited a-C was highlighted when being illuminated (AM 1.5 illumination: 100 mW/cm2, 25 °C). Transmittance spectrum exhibit a large transmittance value (>85%) and absorption coefficient value of 103-104 cm-1 at the visible range of 390 to 790 nm. The atomization of a liquid precursor solution into fine sub-micrometre-sized aerosol droplets in AACVD induced the smooth surface of a-C films. To the best of our knowledge, fabrication of a-C solar cell using this AACVD method has not yet been reported.

  7. microRNA-22 attenuates neuronal cell apoptosis in a cell model of traumatic brain injury

    PubMed Central

    Ma, Ji; Shui, Shaofeng; Han, Xinwei; Guo, Dong; Li, Tengfei; Yan, Lei

    2016-01-01

    Traumatic brain injury (TBI) is a major cause of injury-related deaths, and the mechanism of TBI has become a research focus, but little is known about the mechanism of microRNAs in TBI. The aim of this study is the role of microRNA-22 (miR-22) in TBI-induced neuronal cell apoptosis. Rat cortical neurons were cultured and the TBI model was induced by scratch injury in vitro, before which miR-22 level was altered by transfection of agomir or antagomir. Lactate dehydrogenase (LDH) release and TUNEL assays were performed to examine neuronal cell injury and apoptosis. The activity of caspase 3 (CASP3) and level changes of several apoptosis factors including B-cell lymphoma 2 (BCL2), BCL2-associated X protein (BAX), phosphatase and tensin homolog (PTEN) and v-AKT murine thymoma viral oncogene homolog 1 (AKT1) were detected. Results showed that TBI model cells possessed a downregulated miR-22 level (P < 0.001) and more LDH release and apoptotic cells indicating the aggravated neuronal cell injury and apoptosis induced by TBI. miR-22 agomir attenuated neuronal cell injury and apoptosis of the TBI model. It also caused the corresponding changes in CASP3 activity and other apoptosis factors, with cleaved CASP3, BAX and PTEN inhibited and BCL2 and phosphorylated AKT1 promoted, while miR-22 antagomir had the opposite effects. So miR-22 has neuroprotective roles of attenuating neuronal cell injury and apoptosis induced by TBI, which may be associated with its regulation on apoptosis factors. This study reveals miR-22 as a potential approach to TBI treatment and detailed mechanism remains to be uncovered. PMID:27186313

  8. Epitaxial Thin Film Silicon Solar Cells Fabricated by Hot Wire Chemical Vapor Deposition Below 750 ..deg..C: Preprint

    SciTech Connect

    Alberi, K.; Martin, I. T.; Shub, M.; Teplin, C. W.; Iwaniczko, E.; Xu, Y.; duda, A.; Stradin, P.; Johnston, S. W.; Romero, M. J.; Branz, H. M.; Young, D. L.

    2009-06-01

    We report on fabricating film c-Si solar cells on Si wafer templates by hot-wire chemical vapor deposition. These devices, grown at glass-compatible temperatures < 750..deg..C, demonstrate open-circuit voltages > 500 mV and efficiencies > 5%.

  9. On-chip fabrication of alkali-metal vapor cells utilizing an alkali-metal source tablet

    NASA Astrophysics Data System (ADS)

    Tsujimoto, K.; Ban, K.; Hirai, Y.; Sugano, K.; Tsuchiya, T.; Mizutani, N.; Tabata, O.

    2013-11-01

    We describe a novel on-chip microfabrication technique for the alkali-metal vapor cell of an optically pumped atomic magnetometer (OPAM), utilizing an alkali-metal source tablet (AMST). The newly proposed AMST is a millimeter-sized piece of porous alumina whose considerable surface area holds deposited alkali-metal chloride (KCl) and barium azide (BaN6), source materials that effectively produce alkali-metal vapor at less than 400 °C. Our experiments indicated that the most effective pore size of the AMST is between 60 and 170 µm. The thickness of an insulating glass spacer holding the AMST was designed to confine generated alkali metal to the interior of the vapor cell during its production, and an integrated silicon heater was designed to seal the device using a glass frit, melted at an optimum temperature range of 460-490 °C that was determined by finite element method thermal simulation. The proposed design and AMST were used to successfully fabricate a K cell that was then operated as an OPAM with a measured sensitivity of 50 pT. These results demonstrate that the proposed concept for on-chip microfabrication of alkali-metal vapor cells may lead to effective replacement of conventional glassworking approaches.

  10. MicroRNA-203 represses selection and expansion of oncogenic Hras transformed tumor initiating cells

    PubMed Central

    Riemondy, Kent; Wang, Xiao-jing; Torchia, Enrique C; Roop, Dennis R; Yi, Rui

    2015-01-01

    In many mouse models of skin cancer, only a few tumors typically form even though many cells competent for tumorigenesis receive the same oncogenic stimuli. These observations suggest an active selection process for tumor-initiating cells. Here, we use quantitative mRNA- and miR-Seq to determine the impact of HrasG12V on the transcriptome of keratinocytes. We discover that microRNA-203 is downregulated by HrasG12V. Using a knockout mouse model, we demonstrate that loss of microRNA-203 promotes selection and expansion of tumor-initiating cells. Conversely, restoration of microRNA-203 using an inducible model potently inhibits proliferation of these cells. We comprehensively identify microRNA-203 targets required for Hras-initiated tumorigenesis. These targets include critical regulators of the Ras pathway and essential genes required for cell division. This study establishes a role for the loss of microRNA-203 in promoting selection and expansion of Hras mutated cells and identifies a mechanism through which microRNA-203 antagonizes Hras-mediated tumorigenesis. DOI: http://dx.doi.org/10.7554/eLife.07004.001 PMID:26203562

  11. A MicroRNA Network Dysregulated in Asthma Controls IL-6 Production in Bronchial Epithelial Cells

    PubMed Central

    Louafi, Fethi; Francisco-Garcia, Ana S.; Rupani, Hitasha; Bedke, Nicole; Holgate, Stephen; Howarth, Peter H.; Davies, Donna E.; Sanchez-Elsner, Tilman

    2014-01-01

    MicroRNAs are short non-coding single stranded RNAs that regulate gene expression. While much is known about the effects of individual microRNAs, there is now growing evidence that they can work in co-operative networks. MicroRNAs are known to be dysregulated in many diseases and affect pathways involved in the pathology. We investigated dysregulation of microRNA networks using asthma as the disease model. Asthma is a chronic inflammatory disease of the airways characterized by bronchial hyperresponsiveness and airway remodelling. The airway epithelium is a major contributor to asthma pathology and has been shown to produce an excess of inflammatory and pro-remodelling cytokines such as TGF-β, IL-6 and IL-8 as well as deficient amounts of anti-viral interferons. After performing microRNA arrays, we found that microRNAs -18a, -27a, -128 and -155 are down-regulated in asthmatic bronchial epithelial cells, compared to cells from healthy donors. Interestingly, these microRNAs are predicted in silico to target several components of the TGF-β, IL-6, IL-8 and interferons pathways. Manipulation of the levels of individual microRNAs in bronchial epithelial cells did not have an effect on any of these pathways. Importantly, knock-down of the network of microRNAs miR-18a, -27a, -128 and -155 led to a significant increase of IL-8 and IL-6 expression. Interestingly, despite strong in silico predictions, down-regulation of the pool of microRNAs did not have an effect on the TGF-β and Interferon pathways. In conclusion, using both bioinformatics and experimental tools we found a highly relevant potential role for microRNA dysregulation in the control of IL-6 and IL-8 expression in asthma. Our results suggest that microRNAs may have different roles depending on the presence of other microRNAs. Thus, interpretation of in silico analysis of microRNA function should be confirmed experimentally in the relevant cellular context taking into account interactions with other micro

  12. microRNA Response to Listeria monocytogenes Infection in Epithelial Cells

    PubMed Central

    Izar, Benjamin; Mannala, Gopala Krishna; Mraheil, Mobarak Abu; Chakraborty, Trinad; Hain, Torsten

    2012-01-01

    microRNAs represent a family of very small non-coding RNAs that control several physiologic and pathologic processes, including host immune response and cancer by antagonizing a number of target mRNAs. There is limited knowledge about cell expression and the regulatory role of microRNAs following bacterial infections. We investigated whether infection with a Gram-positive bacterium leads to altered expression of microRNAs involved in the host cell response in epithelial cells. Caco-2 cells were infected with Listeria monocytogenes EGD-e, a mutant strain (ΔinlAB or Δhly) or incubated with purified listeriolysin (LLO). Total RNA was isolated and microRNA and target gene expression was compared to the expression in non-infected cells using microRNA microarrays and qRT-PCR. We identified and validated five microRNAs (miR- 146b, miR-16, let-7a1, miR-145 and miR-155) that were significantly deregulated following listerial infection. We show that expression patterns of particular microRNAs strongly depend on pathogen localization and the presence of bacterial effector proteins. Strikingly, miR-155 which was shown to have an important role in inflammatory responses during infection was induced by wild-type bacteria, by LLO-deficient bacteria and following incubation with purified LLO. It was downregulated following ΔinlAB infection indicating a new potent role for internalins in listerial pathogenicity and miRNA regulation. Concurrently, we observed differences in target transcript expression of the investigated miRNAs. We provide first evidence that L. monocytogenes infection leads to deregulation of a set of microRNAs with important roles in host response. Distinct microRNA expression depends on both LLO and pathogen localization. PMID:22312311

  13. MicroRNA Profiling of Primary Cutaneous Large B-Cell Lymphomas

    PubMed Central

    Koens, Lianne; Qin, Yongjun; Leung, Wai Y.; Corver, Willem E.; Jansen, Patty M.; Willemze, Rein; Vermeer, Maarten H.; Tensen, Cornelis P.

    2013-01-01

    Aberrant expression of microRNAs is widely accepted to be pathogenetically involved in nodal diffuse large B-cell lymphomas (DLBCLs). However, the microRNAs profiles of primary cutaneous large B-cell lymphomas (PCLBCLs) are not yet described. Its two main subtypes, i.e., primary cutaneous diffuse large B-cell lymphoma, leg type (PCLBCL-LT) and primary cutaneous follicle center lymphoma (PCFCL) are characterized by an activated B-cell (ABC)-genotype and a germinal center B-cell (GCB)-genotype, respectively. We performed high-throughput sequencing analysis on frozen tumor biopsies from 19 cases of PCFCL and PCLBCL-LT to establish microRNA profiles. Cluster analysis of the complete microRNome could not distinguish between the two subtypes, but 16 single microRNAs were found to be differentially expressed. Single microRNA RT-qPCR was conducted on formalin-fixed paraffin-embedded tumor biopsies of 20 additional cases, confirming higher expression of miR-9-5p, miR-31-5p, miR-129-2-3p and miR-214-3p in PCFCL as compared to PCLBCL-LT. MicroRNAs previously described to be higher expressed in ABC-type as compared to GCB-type nodal DLBCL were not differentially expressed between PCFCL and PCLBCL-LT. In conclusion, PCFCL and PCLBCL-LT differ in their microRNA profiles. In contrast to their gene expression profile, they only show slight resemblance with the microRNA profiles found in GCB- and ABC-type nodal DLBCL. PMID:24358187

  14. MicroRNA profiling of primary cutaneous large B-cell lymphomas.

    PubMed

    Koens, Lianne; Qin, Yongjun; Leung, Wai Y; Corver, Willem E; Jansen, Patty M; Willemze, Rein; Vermeer, Maarten H; Tensen, Cornelis P

    2013-01-01

    Aberrant expression of microRNAs is widely accepted to be pathogenetically involved in nodal diffuse large B-cell lymphomas (DLBCLs). However, the microRNAs profiles of primary cutaneous large B-cell lymphomas (PCLBCLs) are not yet described. Its two main subtypes, i.e., primary cutaneous diffuse large B-cell lymphoma, leg type (PCLBCL-LT) and primary cutaneous follicle center lymphoma (PCFCL) are characterized by an activated B-cell (ABC)-genotype and a germinal center B-cell (GCB)-genotype, respectively. We performed high-throughput sequencing analysis on frozen tumor biopsies from 19 cases of PCFCL and PCLBCL-LT to establish microRNA profiles. Cluster analysis of the complete microRNome could not distinguish between the two subtypes, but 16 single microRNAs were found to be differentially expressed. Single microRNA RT-qPCR was conducted on formalin-fixed paraffin-embedded tumor biopsies of 20 additional cases, confirming higher expression of miR-9-5p, miR-31-5p, miR-129-2-3p and miR-214-3p in PCFCL as compared to PCLBCL-LT. MicroRNAs previously described to be higher expressed in ABC-type as compared to GCB-type nodal DLBCL were not differentially expressed between PCFCL and PCLBCL-LT. In conclusion, PCFCL and PCLBCL-LT differ in their microRNA profiles. In contrast to their gene expression profile, they only show slight resemblance with the microRNA profiles found in GCB- and ABC-type nodal DLBCL. PMID:24358187

  15. Review of micro/nano technologies and theories for electroporation of biological cells

    NASA Astrophysics Data System (ADS)

    Lee, YiKuen; Deng, PeiGang

    2012-06-01

    Electroporation (EP) is one of the important techniques for the introduction of genes and drugs into cells with intense pulsed electric field to induce nanometer-sized electropores on cell membranes. Recently, micro/nano technology has been applied to many novel micro EP devices which can not only significantly increase uptake of biomolecules, DNA transfection and cell viability, but also enable large-scale single-cell EP. However, most EP theories developed in the past three decades can not precisely predict the experimental results of EP of biological cells. With the advanced micro EP chips for large-scale single-cell EP experiments, more precise EP theoretical models can be developed to describe the complicated multiscale dynamic behavior of EP.

  16. Micro- and Nanoengineering Approaches to Control Stem Cell-Biomaterial Interactions

    PubMed Central

    Dolatshahi-Pirouz, Alireza; Nikkhah, Mehdi; Kolind, Kristian; Dokmeci, Mehmet R.; Khademhosseini, Ali

    2011-01-01

    As our population ages, there is a greater need for a suitable supply of engineered tissues to address a range of debilitating ailments. Stem cell based therapies are envisioned to meet this emerging need. Despite significant progress in controlling stem cell differentiation, it is still difficult to engineer human tissue constructs for transplantation. Recent advances in micro- and nanofabrication techniques have enabled the design of more biomimetic biomaterials that may be used to direct the fate of stem cells. These biomaterials could have a significant impact on the next generation of stem cell based therapies. Here, we highlight the recent progress made by micro- and nanoengineering techniques in the biomaterials field in the context of directing stem cell differentiation. Particular attention is given to the effect of surface topography, chemistry, mechanics and micro- and nanopatterns on the differentiation of embryonic, mesenchymal and neural stem cells. PMID:24956299

  17. Wafer-level filling of microfabricated atomic vapor cells based on thin-film deposition and photolysis of cesium azide

    SciTech Connect

    Liew, Li-Anne; Moreland, John; Gerginov, Vladislav

    2007-03-12

    The thin-film deposition and photodecomposition of cesium azide are demonstrated and used to fill arrays of miniaturized atomic resonance cells with cesium and nitrogen buffer gas for chip-scale atomic-based instruments. Arrays of silicon cells are batch fabricated on wafers into which cesium azide is deposited by vacuum thermal evaporation. After vacuum sealing, the cells are irradiated with ultraviolet radiation, causing the azide to photodissociate into pure cesium and nitrogen in situ. This technology integrates the vapor-cell fabrication and filling procedures into one continuous and wafer-level parallel process, and results in cells that are optically transparent and chemically pure.

  18. A smart fully integrated micromachined separator with soft magnetic micro-pillar arrays for cell isolation

    NASA Astrophysics Data System (ADS)

    Dong, Tao; Su, Qianhua; Yang, Zhaochu; Zhang, Yulong; Egeland, Eirik B.; Gu, Dan D.; Calabrese, Paolo; Kapiris, Matteo J.; Karlsen, Frank; Minh, Nhut T.; Wang, K.; Jakobsen, Henrik

    2010-11-01

    A smart fully integrated micromachined separator with soft magnetic micro-pillar arrays has been developed and demonstrated, which can merely employ one independent lab-on-chip to realize cell isolation. The simulation, design, microfabrication and test for the new electromagnetic micro separator were executed. The simulation results of the electromagnetic field in the separator show that special soft magnetic micro-pillar arrays can amplify and redistribute the electromagnetic field generated by the micro-coils. The separator can be equipped with a strong magnetic field to isolate the target cells with a considerably low input current. The micro separator was fabricated by micro-processing technology. An electroplating bath was hired to deposit NiCo/NiFe to fabricate the micro-pillar arrays. An experimental system was set up to verify the function of the micro separator by isolating the lymphocytes, in which the human whole blood mixed with Dynabeads® FlowComp Flexi and monoclonal antibody MHCD2704 was used as the sample. The results show that the electromagnetic micro separator with an extremely low input current can recognize and capture the target lymphocytes with a high efficiency, the separation ratio reaching more than 90% at a lower flow rate. For the electromagnetic micro separator, there is no external magnetizing field required, and there is no extra cooling system because there is less Joule heat generated due to the lower current. The magnetic separator is totally reusable, and it can be used to separate cells or proteins with common antigens.

  19. Single cell adhesion force measurement for cell viability identification using an AFM cantilever-based micro putter

    NASA Astrophysics Data System (ADS)

    Shen, Yajing; Nakajima, Masahiro; Kojima, Seiji; Homma, Michio; Kojima, Masaru; Fukuda, Toshio

    2011-11-01

    Fast and sensitive cell viability identification is a key point for single cell analysis. To address this issue, this paper reports a novel single cell viability identification method based on the measurement of single cell shear adhesion force using an atomic force microscopy (AFM) cantilever-based micro putter. Viable and nonviable yeast cells are prepared and put onto three kinds of substrate surfaces, i.e. tungsten probe, gold and ITO substrate surfaces. A micro putter is fabricated from the AFM cantilever by focused ion beam etching technique. The spring constant of the micro putter is calibrated using the nanomanipulation approach. The shear adhesion force between the single viable or nonviable cell and each substrate is measured using the micro putter based on the nanorobotic manipulation system inside an environmental scanning electron microscope. The adhesion force is calculated based on the deflection of the micro putter beam. The results show that the adhesion force of the viable cell to the substrate is much larger than that of the nonviable cell. This identification method is label free, fast, sensitive and can give quantitative results at the single cell level.

  20. The microRNA-212/132 cluster regulates B cell development by targeting Sox4

    PubMed Central

    Mehta, Arnav; Mann, Mati; Zhao, Jimmy L.; Marinov, Georgi K.; Majumdar, Devdoot; Garcia-Flores, Yvette; Du, Xiaomi; Erikci, Erdem; Chowdhury, Kamal

    2015-01-01

    MicroRNAs have emerged as key regulators of B cell fate decisions and immune function. Deregulation of several microRNAs in B cells leads to the development of autoimmune disease and cancer in mice. We demonstrate that the microRNA-212/132 cluster (miR-212/132) is induced in B cells in response to B cell receptor signaling. Enforced expression of miR-132 results in a block in early B cell development at the prepro–B cell to pro–B cell transition and induces apoptosis in primary bone marrow B cells. Importantly, loss of miR-212/132 results in accelerated B cell recovery after antibody-mediated B cell depletion. We find that Sox4 is a target of miR-132 in B cells. Co-expression of SOX4 with miR-132 rescues the defect in B cell development from overexpression of miR-132 alone, thus suggesting that miR-132 may regulate B lymphopoiesis through Sox4. In addition, we show that the expression of miR-132 can inhibit cancer development in cells that are prone to B cell cancers, such as B cells expressing the c-Myc oncogene. We have thus uncovered miR-132 as a novel contributor to B cell development. PMID:26371188

  1. MicroRNA Expression and Clinical Outcome of Small Cell Lung Cancer

    PubMed Central

    Lee, Jih-Hsiang; Voortman, Johannes; Dingemans, Anne-Marie C.; Voeller, Donna M.; Pham, Trung; Wang, Yisong; Giaccone, Giuseppe

    2011-01-01

    The role of microRNAs in small-cell lung carcinoma (SCLC) is largely unknown. miR-34a is known as a p53 regulated tumor suppressor microRNA in many cancer types. However, its therapeutic implication has never been studied in SCLC, a cancer type with frequent dysfunction of p53. We investigated the expression of a panel of 7 microRNAs (miR-21, miR-29b, miR-34a/b/c, miR-155, and let-7a) in 31 SCLC tumors, 14 SCLC cell lines, and 26 NSCLC cell lines. We observed significantly lower miR-21, miR-29b, and miR-34a expression in SCLC cell lines than in NSCLC cell lines. The expression of the 7 microRNAs was unrelated to SCLC patients' clinical characteristics and was neither prognostic in term of overall survival or progression-free survival nor predictive of treatment response. Overexpression or downregulation of miR-34a did not influence SCLC cell viability. The expression of these 7 microRNAs also did not predict in vitro sensitivity to cisplatin or etoposide in SCLC cell lines. Overexpression or downregulation of miR-34a did not influence sensitivity to cisplatin or etoposide in SCLC cell lines. In contrast to downregulation of the miR-34a target genes cMET and Axl by overexpression of miR-34a in NSCLC cell lines, the intrinsic expression of cMET and Axl was low in SCLC cell lines and was not influenced by overexpression of miR-34a. Our results suggest that the expression of the 7 selected microRNAs are not prognostic in SCLC patients, and miR-34a is unrelated to the malignant behavior of SCLC cells and is unlikely to be a therapeutic target. PMID:21731696

  2. Fabrication of efficient planar perovskite solar cells using a one-step chemical vapor deposition method

    PubMed Central

    Tavakoli, Mohammad Mahdi; Gu, Leilei; Gao, Yuan; Reckmeier, Claas; He, Jin; Rogach, Andrey L.; Yao, Yan; Fan, Zhiyong

    2015-01-01

    Organometallic trihalide perovskites are promising materials for photovoltaic applications, which have demonstrated a rapid rise in photovoltaic performance in a short period of time. We report a facile one-step method to fabricate planar heterojunction perovskite solar cells by chemical vapor deposition (CVD), with a solar power conversion efficiency of up to 11.1%. We performed a systematic optimization of CVD parameters such as temperature and growth time to obtain high quality films of CH3NH3PbI3 and CH3NH3PbI3-xClx perovskite. Scanning electron microscopy and time resolved photoluminescence data showed that the perovskite films have a large grain size of more than 1 micrometer, and carrier life-times of 10 ns and 120 ns for CH3NH3PbI3 and CH3NH3PbI3-xClx, respectively. This is the first demonstration of a highly efficient perovskite solar cell using one step CVD and there is likely room for significant improvement of device efficiency. PMID:26392200

  3. Organic solar cells with graphene electrodes and vapor printed poly(3,4-ethylenedioxythiophene) as the hole transporting layers.

    PubMed

    Park, Hyesung; Howden, Rachel M; Barr, Miles C; Bulović, Vladimir; Gleason, Karen; Kong, Jing

    2012-07-24

    For the successful integration of graphene as a transparent conducting electrode in organic solar cells, proper energy level alignment at the interface between the graphene and the adjacent organic layer is critical. The role of a hole transporting layer (HTL) thus becomes more significant due to the generally lower work function of graphene compared to ITO. A commonly used HTL material with ITO anodes is poly(3,4-ethylenedioxythiophene) (PEDOT) with poly(styrenesulfonate) (PSS) as the solid-state dopant. However, graphene's hydrophobic surface renders uniform coverage of PEDOT:PSS (aqueous solution) by spin-casting very challenging. Here, we introduce a novel, yet simple, vapor printing method for creating patterned HTL PEDOT layers directly onto the graphene surface. Vapor printing represents the implementation of shadow masking in combination with oxidative chemical vapor deposition (oCVD). The oCVD method was developed for the formation of blanket (i.e., unpatterened) layers of pure PEDOT (i.e., no PSS) with systematically variable work function. In the unmasked regions, vapor printing produces complete, uniform, smooth layers of pure PEDOT over graphene. Graphene electrodes were synthesized under low-pressure chemical vapor deposition (LPCVD) using a copper catalyst. The use of another electron donor material, tetraphenyldibenzoperiflanthene, instead of copper phthalocyanine in the organic solar cells also improves the power conversion efficiency. With the vapor printed HTL, the devices using graphene electrodes yield comparable performances to the ITO reference devices (η(p,LPCVD) = 3.01%, and η(p,ITO) = 3.20%). PMID:22724887

  4. MicroRNA-196b promotes cell proliferation and suppress cell differentiation in vitro

    SciTech Connect

    Cao, Donglin Hu, Liangshan; Lei, Da; Fang, Xiaolin; Zhang, Zhihong; Wang, Ting; Lin, Maorui; Huang, Jiwei; Yang, Huawen; Zhou, Xuan; Zhong, Limei

    2015-01-30

    Highlights: • miRNA-196b increases proliferation and blocks differentiation of progenitor cell. • miRNA-196b inhibits apoptosis and increases viability of cells lines. • Forced expression of miR-196b blocks the differentiation of THP1 induced by PMA. - Abstract: MicroRNA-196b (miR-196b) is frequently amplified and aberrantly overexpressed in acute leukemias. To investigate the role of miR-196b in acute leukemias, it has been observed that forced expression of this miRNA increases proliferation and inhibits apoptosis in human cell lines. More importantly, we show that this miRNA can significantly increase the colony-forming capacity of mouse normal bone marrow progenitor cells alone, as well as partially blocking the cells from differentiation. Taken together, our studies suggest that miRNA-196b may play an essential role in the development of MLL-associated leukemias through inhibiting cell differentiation and apoptosis, while promoting cell proliferation.

  5. MicroRNA Expression Patterns Related to Merkel Cell Polyomavirus Infection in Human Merkel Cell Carcinoma

    PubMed Central

    Xie, Hong; Lee, Linkiat; Caramuta, Stefano; Höög, Anders; Browaldh, Nanna; Björnhagen, Viveca; Larsson, Catharina; Lui, Weng-Onn

    2014-01-01

    Merkel cell carcinoma (MCC) is an aggressive and lethal type of neuroendocrine skin cancer. Mutated Merkel cell polyomavirus (MCV) is commonly found in MCC, and leads to upregulation of the survivin oncogene. However, ∼20% of MCC tumors do not have detectable MCV, suggesting alternative etiologies for this tumor type. In this study, our aim was to evaluate microRNA (miRNA) expression profiles and their associations with MCV status and clinical outcomes in MCC. We showed that miRNA expression profiles were distinct between MCV-positive (MCV+) and MCV-negative (MCV−) MCCs and further validated that miR-203, miR-30a-3p, miR-769-5p, miR-34a, miR-30a-5p, and miR-375 were significantly different. We also identified a subset of miRNAs associated with tumor metastasis and MCC-specific survival. Functionally, overexpression of miR-203 was found to inhibit cell growth, induce cell cycle arrest, and regulate survivin expression in MCV− MCC cells, but not in MCV+ MCC cells. Our findings reveal a mechanism of survivin expression regulation in MCC cells, and provide insights into the role of miRNAs in MCC tumorigenesis. PMID:23962809

  6. Differential expression of microRNAs in 2-cell and 4-cell mouse embryos.

    PubMed

    Wang, Pei; Cui, Ji; Zhao, Chun; Zhou, Lin; Guo, Xirong; Shen, Rong; Zhang, Junqiang; Ling, Xiufeng

    2014-11-01

    In vitro fertilized (IVF) human embryos have a high incidence of developmental arrest before the blastocyst stage, therefore characterization of the molecular mechanisms that regulate embryo development is urgently required. Post-transcriptional control by microRNAs (miRNAs) is one of the most investigated RNA control mechanisms, and is hypothesized to be involved actively in developmental arrest in preimplantation embryos. In this study, we extracted total RNA from mouse 2-cell and 4-cell embryos. Using a miRNA microarray, 192 miRNAs were found to be differentially expressed in 4-cell embryos and 2-cell embryos; 122 miRNAs were upregulated and 70 were downregulated in 4-cell embryos. The microarray results were confirmed by real-time quantitative RT-PCR for six miRNAs (mmu-miR-467h, mmu-miR-466d-3p, mmu-miR-292-5p, mmu-miR-154, mmu-miR-2145, and mmu-miR-706). Cdca4 and Tcf12 were identified as miR-154 target genes by target prediction analysis. This study provides a developmental map for a large number of miRNAs in 2-cell and 4-cell embryos. The function of these miRNAs and the mechanisms by which they modulate embryonic developmental arrest require further study. The results of this study have potential applications in the field of reproductive medicine. PMID:23731853

  7. MicroRNA Regulation of Brain Tumour Initiating Cells in Central Nervous System Tumours

    PubMed Central

    Vijayakumar, Thusyanth; Bakhshinyan, David; Venugopal, Chitra; Singh, Sheila K.

    2015-01-01

    CNS tumours occur in both pediatric and adult patients and many of these tumours are associated with poor clinical outcome. Due to a paradigm shift in thinking for the last several years, these tumours are now considered to originate from a small population of stem-like cells within the bulk tumour tissue. These cells, termed as brain tumour initiating cells (BTICs), are perceived to be regulated by microRNAs at the posttranscriptional/translational levels. Proliferation, stemness, differentiation, invasion, angiogenesis, metastasis, apoptosis, and cell cycle constitute some of the significant processes modulated by microRNAs in cancer initiation and progression. Characterization and functional studies on oncogenic or tumour suppressive microRNAs are made possible because of developments in sequencing and microarray techniques. In the current review, we bring recent knowledge of the role of microRNAs in BTIC formation and therapy. Special attention is paid to two highly aggressive and well-characterized brain tumours: gliomas and medulloblastoma. As microRNA seems to be altered in the pathogenesis of many human diseases, “microRNA therapy” may now have potential to improve outcomes for brain tumour patients. In this rapidly evolving field, further understanding of miRNA biology and its contribution towards cancer can be mined for new therapeutic tools. PMID:26064134

  8. Method and apparatus for fabricating a thin-film solar cell utilizing a hot wire chemical vapor deposition technique

    DOEpatents

    Wang, Qi; Iwaniczko, Eugene

    2006-10-17

    A thin-film solar cell is provided. The thin-film solar cell comprises an a-SiGe:H (1.6 eV) n-i-p solar cell having a deposition rate of at least ten (10) .ANG./second for the a-SiGe:H intrinsic layer by hot wire chemical vapor deposition. A method for fabricating a thin film solar cell is also provided. The method comprises depositing a n-i-p layer at a deposition rate of at least ten (10) .ANG./second for the a-SiGe:H intrinsic layer.

  9. Surface enhanced Raman spectroscopy measurements of MCF7 cells adhesion in confined micro-environments

    NASA Astrophysics Data System (ADS)

    De Vitis, Stefania; Coluccio, Maria Laura; Gentile, Francesco; Malara, Natalia; Perozziello, Gerardo; Dattola, Elisabetta; Candeloro, Patrizio; Di Fabrizio, Enzo

    2016-01-01

    Undoubtedly cells can perceive the external environment, not only from a biochemical point of view with the related signalling pathways, but also from a physical and topographical perspective. In this sense controlled three dimensional micro-structures as well as patterns at the nano-scale can affect and guide the cell evolution and proliferation, due to the fact that the surrounding environment is no longer isotropic (like the flat surfaces of standard cell culturing) but possesses well defined symmetries and anisotropies. In this work regular arrays of silicon micro-pillars with hexagonal arrangement are used as culturing substrates for MCF-7 breast cancer cells. The characteristic size and spacing of the pillars are tens of microns, comparable with MCF-7 cell dimensions and then well suited to induce acceptable external stimuli. It is shown that these cells strongly modify their morphology for adapting themselves to the micro-structured landscape, by means of protrusions from the main body of the cell. Scanning electron microscopy along with both Raman micro-spectroscopy and surface enhanced Raman spectroscopy are used for topographical and biochemical studies of the new cell arrangement. We have revealed that single MCF-7 cells exploit their capability to produce invadopodia, usually generated to invade the neighboring tissue in metastatic activity, for spanning and growing across separate pillars.

  10. The thermomechanical stability of micro-solid oxide fuel cells fabricated on anodized aluminum oxide membranes

    NASA Astrophysics Data System (ADS)

    Kwon, Chang-Woo; Lee, Jae-Il; Kim, Ki-Bum; Lee, Hae-Weon; Lee, Jong-Ho; Son, Ji-Won

    2012-07-01

    The thermomechanical stability of micro-solid oxide fuel cells (micro-SOFCs) fabricated on an anodized aluminum oxide (AAO) membrane template is investigated. The full structure consists of the following layers: AAO membrane (600 nm)/Pt anode/YSZ electrolyte (900 nm)/porous Pt cathode. The utilization of a 600-nm-thick AAO membrane significantly improves the thermomechanical stability due to its well-known honeycomb-shaped nanopore structure. Moreover, the Pt anode layer deposited in between the AAO membrane and the YSZ electrolyte preserves its integrity in terms of maintaining the triple-phase boundary (TPB) and electrical conductivity during high-temperature operation. Both of these results guarantee thermomechanical stability of the micro-SOFC and extend the cell lifetime, which is one of the most critical issues in the fabrication of freestanding membrane-type micro-SOFCs.

  11. Smoking-related microRNAs and mRNAs in human peripheral blood mononuclear cells.

    PubMed

    Su, Ming-Wei; Yu, Sung-Liang; Lin, Wen-Chang; Tsai, Ching-Hui; Chen, Po-Hua; Lee, Yungling Leo

    2016-08-15

    Teenager smoking is of great importance in public health. Functional roles of microRNAs have been documented in smoke-induced gene expression changes, but comprehensive mechanisms of microRNA-mRNA regulation and benefits remained poorly understood. We conducted the Teenager Smoking Reduction Trial (TSRT) to investigate the causal association between active smoking reduction and whole-genome microRNA and mRNA expression changes in human peripheral blood mononuclear cells (PBMC). A total of 12 teenagers with a substantial reduction in smoke quantity and a decrease in urine cotinine/creatinine ratio were enrolled in genomic analyses. In Gene Set Enrichment Analysis (GSEA) and Ingenuity Pathway Analysis (IPA), differentially expressed genes altered by smoke reduction were mainly associated with glucocorticoid receptor signaling pathway. The integrative analysis of microRNA and mRNA found eleven differentially expressed microRNAs negatively correlated with predicted target genes. CD83 molecule regulated by miR-4498 in human PBMC, was critical for the canonical pathway of communication between innate and adaptive immune cells. Our data demonstrated that microRNAs could regulate immune responses in human PBMC after habitual smokers quit smoking and support the potential translational value of microRNAs in regulating disease-relevant gene expression caused by tobacco smoke. PMID:27321975

  12. Smart Energy Management and Control for Fuel Cell Based Micro-Grid Connected Neighborhoods

    SciTech Connect

    Dr. Mohammad S. Alam

    2006-03-15

    Fuel cell power generation promises to be an efficient, pollution-free, reliable power source in both large scale and small scale, remote applications. DOE formed the Solid State Energy Conversion Alliance with the intention of breaking one of the last barriers remaining for cost effective fuel cell power generation. The Alliance’s goal is to produce a core solid-state fuel cell module at a cost of no more than $400 per kilowatt and ready for commercial application by 2010. With their inherently high, 60-70% conversion efficiencies, significantly reduced carbon dioxide emissions, and negligible emissions of other pollutants, fuel cells will be the obvious choice for a broad variety of commercial and residential applications when their cost effectiveness is improved. In a research program funded by the Department of Energy, the research team has been investigating smart fuel cell-operated residential micro-grid communities. This research has focused on using smart control systems in conjunction with fuel cell power plants, with the goal to reduce energy consumption, reduce demand peaks and still meet the energy requirements of any household in a micro-grid community environment. In Phases I and II, a SEMaC was developed and extended to a micro-grid community. In addition, an optimal configuration was determined for a single fuel cell power plant supplying power to a ten-home micro-grid community. In Phase III, the plan is to expand this work to fuel cell based micro-grid connected neighborhoods (mini-grid). The economic implications of hydrogen cogeneration will be investigated. These efforts are consistent with DOE’s mission to decentralize domestic electric power generation and to accelerate the onset of the hydrogen economy. A major challenge facing the routine implementation and use of a fuel cell based mini-grid is the varying electrical demand of the individual micro-grids, and, therefore, analyzing these issues is vital. Efforts are needed to determine

  13. Real time monitoring of temperature of a micro proton exchange membrane fuel cell.

    PubMed

    Lee, Chi-Yuan; Lee, Shuo-Jen; Hu, Yuh-Chung; Shih, Wen-Pin; Fan, Wei-Yuan; Chuang, Chih-Wei

    2009-01-01

    Silicon micro-hole arrays (Si-MHA) were fabricated as a gas diffusion layer (GDL) in a micro fuel cell using the micro-electro-mechanical-systems (MEMS) fabrication technique. The resistance temperature detector (RTD) sensor was integrated with the GDL on a bipolar plate to measure the temperature inside the fuel cell. Experimental results demonstrate that temperature was generally linearly related to resistance and that accuracy and sensitivity were within 0.5 °C and 1.68×10(-3)/°C, respectively. The best experimental performance was 9.37 mW/cm(2) at an H(2)/O(2) dry gas flow rate of 30/30 SCCM. Fuel cell temperature during operation was 27 °C, as measured using thermocouples in contact with the backside of the electrode. Fuel cell operating temperature measured in situ was 30.5 °C. PMID:22573963

  14. Development of Nano/Micro Probes for Femtoliter Volume and Single Cell Measurements

    NASA Astrophysics Data System (ADS)

    Gao, Yang

    Single cell analysis has recently emerged as an important field of biomedical re- search. It is now clear that heterogeneity of cell metabolism functions in complex biological systems is correlated to changes in biological function and disease processes. A variety of nano/micro probes were developed to enable investigation of cells properties such as membrane stiffness, pH value. However, very few designs were focused on single cell metabolic function studies. There is a critical need for technologies that provide analysis of heterogeneity of cell metabolic functions, especially on metabolism. Nevertheless, the few existing approaches suffer from fundamental defects and need to be improved. This work focused on developing nano/micro probes that are suitable for single cell functionality investigation. Both types of probes are designed to measure cell-to-cell/time-to-time heterogeneity in metabolic functions over a long period of time. Lab-made carbon nanoprobes were developed especially for electro-physiological measurement. The unique structure of the carbon nanoprobes makes them suitable for important intracellular applications like trans-membrane potential measurements and various electrochemical measurement for cell function studies. While it is important of have ability to carry out intracellular measure, there are also occasions where the information of a cell as a whole is collected. One of the most important indicator of a cells metabolic functions is cell respiration rate/oxygen consumption rate. A micro-perfusion based multi-functional single cell sensing probe was the developed to carry out measurements on cell as a whole. Formed by a double-barrel theta pipette, the perfusion flow enables the direct measurement of the metabolic flux for example oxygen consumption rate. In conclusion, this work developed nano/micro-probes as novel single cell investigation tools. The data acquired from these tools could provide valuable assistance on applications

  15. Simulation and design optimization of transparent heaters for spectroscopic micro cells

    NASA Astrophysics Data System (ADS)

    Völlm, Henning; Herrmann, Jonathan; Maier, Reinhard; Feili, Dara; Häublein, Volker; Ryssel, Heiner; Seidel, Helmut

    2013-05-01

    For several applications, micro cells with a uniform temperature profile and at least one optical port are required. One example for those cells is the physics package of a chip-scale-atomic-clock. It is necessary that the micro chambers are heated homogeneously to 353 K using a low energy consumption heater. In this work transparent heating structures are investigated to achieve this goal. First an analytical approach is used to describe the behavior of thermal energy dissipation of the heating structures. Then different approaches of possible heater structures are simulated to find the optimal basic configuration. Furthermore, this configuration is optimized to obtain a uniform temperature distribution in the whole cell.

  16. Trapping light with micro lenses in thin film organic photovoltaic cells.

    PubMed

    Tvingstedt, Kristofer; Dal Zilio, Simone; Inganäs, Olle; Tormen, Massimo

    2008-12-22

    We demonstrate a novel light trapping configuration based on an array of micro lenses in conjunction with a self aligned array of micro apertures located in a highly reflecting mirror. When locating the light trapping element, that displays strong directional asymmetric transmission, in front of thin film organic photovoltaic cells, an increase in cell absorption is obtained. By recycling reflected photons that otherwise would be lost, thinner films with more beneficial electrical properties can effectively be deployed. The light trapping element enhances the absorption rate of the solar cell and increases the photocurrent by as much as 25%. PMID:19104592

  17. The role of mesoscopic PCBM crystallites in solvent vapor annealed copolymer solar cells.

    PubMed

    Bull, Tricia A; Pingree, Liam S C; Jenekhe, Samson A; Ginger, David S; Luscombe, Christine K

    2009-03-24

    Solution processable methanofullerene-based solar cells are the most widely studied class of organic photovoltaics (OPVs). The evolution of the electronic properties with solvent vapor annealing (SVA) in polyfluorene-copolymer and [6,6]phenyl-C61-butyric acid methyl ester (PCBM) blended OPVs is studied using various scanning probe techniques: light beam induced current spectroscopy (LBIC), conductive atomic force microscopy (c-AFM), and photoconductive AFM (pc-AFM). We demonstrate that SVA improves the power conversion efficiency by 40% while forming mesoscopic PCBM crystallites and a approximately 3 nm copolymer-rich overlayer at the cathode interface. We find that the large crystallites created during annealing do not directly improve the local performance of the device, but instead attribute the performance improvement to the ripened blend morphology and an increase in the hole mobility of the copolymer in comparison to the unannealed blend. The PCBM-rich aggregates act as a sink for excess PCBM, although excess PCBM is initially required to form the appropriate structural features prior to the annealing process. PMID:19228011

  18. Investigation of anti-Relaxation coatings for alkali-metal vapor cells using surface science techniques

    SciTech Connect

    Seltzer, S. J.; Michalak, D. J.; Donaldson, M. H.; Balabas, M. V.; Barber, S. K.; Bernasek, S. L.; Bouchiat, M.-A.; Hexemer, A.; Hibberd, A. M.; Jackson Kimball, D. F.; Jaye, C.; Karaulanov, T.; Narducci, F. A.; Rangwala, S. A.; Robinson, H. G.; Shmakov, A. K.; Voronov, D. L.; Yashchuk, V. V.; Pines, A.; Budker, D.

    2010-10-11

    Many technologies based on cells containing alkali-metal atomic vapor benefit from the use of antirelaxation surface coatings in order to preserve atomic spin polarization. In particular, paraffin has been used for this purpose for several decades and has been demonstrated to allow an atom to experience up to 10?000 collisions with the walls of its container without depolarizing, but the details of its operation remain poorly understood. We apply modern surface and bulk techniques to the study of paraffin coatings in order to characterize the properties that enable the effective preservation of alkali spin polarization. These methods include Fourier transform infrared spectroscopy, differential scanning calorimetry, atomic force microscopy, near-edge x-ray absorption fine structure spectroscopy, and x-ray photoelectron spectroscopy. We also compare the light-induced atomic desorption yields of several different paraffin materials. Experimental results include the determination that crystallinity of the coating material is unnecessary, and the detection of C=C double bonds present within a particular class of effective paraffin coatings. Further study should lead to the development of more robust paraffin antirelaxation coatings, as well as the design and synthesis of new classes of coating materials.

  19. Ground-state magneto-optical resonances in cesium vapor confined in an extremely thin cell

    NASA Astrophysics Data System (ADS)

    Andreeva, C.; Atvars, A.; Auzinsh, M.; Blush, K.; Cartaleva, S.; Petrov, L.; Slavov, D.

    2007-12-01

    Experimental and theoretical studies are presented related to the ground-state magneto-optical resonance observed in cesium vapor confined in an extremely thin cell (ETC), with thickness equal to the wavelength of the irradiating light. It is shown that utilization of the ETC allows one to examine the formation of a magneto-optical resonance on the individual hyperfine transitions, thus distinguishing processes resulting in dark (reduced absorption) or bright (enhanced absorption) resonance formation. We report experimental evidence of bright magneto-optical resonance sign reversal in Cs atoms confined in an ETC. A theoretical model is proposed based on the optical Bloch equations that involves the elastic interaction processes of atoms in the ETC with its walls, resulting in depolarization of the Cs excited state, which is polarized by the exciting radiation. This depolarization leads to the sign reversal of the bright resonance. Using the proposed model, the magneto-optical resonance amplitude and width as a function of laser power are calculated and compared with the experimental ones. The numerical results are in good agreement with those of experiment.

  20. Electrochemically switchable platform for the micro-patterning and release of heterotypic cell sheets.

    PubMed

    Guillaume-Gentil, Orane; Gabi, Michael; Zenobi-Wong, Marcy; Vörös, Janos

    2011-02-01

    This article describes a dynamic platform in which the biointerfacial properties of micro-patterned domains can be switched electrochemically through the spatio-temporally controlled dissolution and adsorption of polyelectrolyte coatings. Insulating SU-8 micro-patterns created on a transparent indium tin oxide electrode by photolithography allowed for the local control over the electrochemical dissolution of polyelectrolyte mono- and multilayers, with polyelectrolytes shielded from the electrochemical treatment by the underlying photoresist stencil. The platform allowed for the creation of micro-patterned cell co-cultures through the electrochemical removal of a non-fouling polyelectrolyte coating and the localized adsorption of a cell adhesive one after attachment of the first cell population. In addition, the use of weak adhesive polyelectrolyte coatings on the photoresist domains allowed for the detachment of a contiguous heterotypic cell sheet upon electrochemical trigger. Cells grown on the ITO domains peeled off upon electrochemical dissolution of the sacrificial polyelectrolyte substrate, whereas adjacent cell areas on the insulated weakly adhesive substrate easily detached through the contractile force generated by neighboring cells. This electrochemical strategy for the micro-patterning and detachment of heterotypic cell sheets combines simplicity, precision and versatility, and presents great prospects for the creation of cellular constructs which mimic the cellular complexity of native tissues. PMID:21057978

  1. Amplification of multiple genomic loci from single cells isolated by laser micro-dissection of tissues

    PubMed Central

    Frumkin, Dan; Wasserstrom, Adam; Itzkovitz, Shalev; Harmelin, Alon; Rechavi, Gideon; Shapiro, Ehud

    2008-01-01

    Background Whole genome amplification (WGA) and laser assisted micro-dissection represent two recently developed technologies that can greatly advance biological and medical research. WGA allows the analysis of multiple genomic loci from a single genome and has been performed on single cells from cell suspensions and from enzymatically-digested tissues. Laser micro-dissection makes it possible to isolate specific single cells from heterogeneous tissues. Results Here we applied for the first time WGA on laser micro-dissected single cells from stained tissue sections, and developed a protocol for sequentially performing the two procedures. The combined procedure allows correlating the cell's genome with its natural morphology and precise anatomical position. From each cell we amplified 122 genomic and mitochondrial loci. In cells obtained from fresh tissue sections, 64.5% of alleles successfully amplified to ~700000 copies each, and mitochondrial DNA was amplified successfully in all cells. Multiplex PCR amplification and analysis of cells from pre-stored sections yielded significantly poorer results. Sequencing and capillary electrophoresis of WGA products allowed detection of slippage mutations in microsatellites (MS), and point mutations in P53. Conclusion Comprehensive genomic analysis of single cells from stained tissue sections opens new research opportunities for cell lineage and depth analyses, genome-wide mutation surveys, and other single cell assays. PMID:18284708

  2. 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

  3. 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. PMID:24339188

  4. Micro-spectroscopy on silicon wafers and solar cells

    PubMed Central

    2011-01-01

    Micro-Raman (μRS) and micro-photoluminescence spectroscopy (μPLS) are demonstrated as valuable characterization techniques for fundamental research on silicon as well as for technological issues in the photovoltaic production. We measure the quantitative carrier recombination lifetime and the doping density with submicron resolution by μPLS and μRS. μPLS utilizes the carrier diffusion from a point excitation source and μRS the hole density-dependent Fano resonances of the first order Raman peak. This is demonstrated on micro defects in multicrystalline silicon. In comparison with the stress measurement by μRS, these measurements reveal the influence of stress on the recombination activity of metal precipitates. This can be attributed to the strong stress dependence of the carrier mobility (piezoresistance) of silicon. With the aim of evaluating technological process steps, Fano resonances in μRS measurements are analyzed for the determination of the doping density and the carrier lifetime in selective emitters, laser fired doping structures, and back surface fields, while μPLS can show the micron-sized damage induced by the respective processes. PMID:21711723

  5. Micro-spectroscopy on silicon wafers and solar cells.

    PubMed

    Gundel, Paul; Schubert, Martin C; Heinz, Friedemann D; Woehl, Robert; Benick, Jan; Giesecke, Johannes A; Suwito, Dominik; Warta, Wilhelm

    2011-01-01

    Micro-Raman (μRS) and micro-photoluminescence spectroscopy (μPLS) are demonstrated as valuable characterization techniques for fundamental research on silicon as well as for technological issues in the photovoltaic production. We measure the quantitative carrier recombination lifetime and the doping density with submicron resolution by μPLS and μRS. μPLS utilizes the carrier diffusion from a point excitation source and μRS the hole density-dependent Fano resonances of the first order Raman peak. This is demonstrated on micro defects in multicrystalline silicon. In comparison with the stress measurement by μRS, these measurements reveal the influence of stress on the recombination activity of metal precipitates. This can be attributed to the strong stress dependence of the carrier mobility (piezoresistance) of silicon. With the aim of evaluating technological process steps, Fano resonances in μRS measurements are analyzed for the determination of the doping density and the carrier lifetime in selective emitters, laser fired doping structures, and back surface fields, while μPLS can show the micron-sized damage induced by the respective processes. PMID:21711723

  6. A study of vapor CdCl{sub 2} treatment by CSS in CdS/CdTe solar cells

    SciTech Connect

    Rios-Flores, A.; Pena, J.L.; Castro-Pena, V.; Ares, O.; Castro-Rodriguez, R.; Bosio, A.

    2010-06-15

    We report the effect of CdCl{sub 2} vapor treatment on the photovoltaic parameters of CdS/CdTe solar cells. Vapor treatment allows combining CdCl{sub 2} exposure time and annealing in one step. In this alternative treatment, the CdS/CdTe substrates were treated with CdCl{sub 2} vapor in a close spaced sublimation (CSS) configuration. The substrate temperature and CdCl{sub 2} powder source temperature were 400 C. The treatment was done by varying the treatment time (t) from 15 to 90 min. Such solar cells are examined by measuring their current density versus voltage (J-V) characteristics. The open-circuit voltage (V{sub oc}), short circuit current density (J{sub sc}) and fill factor (FF) of our best cell, fabricated and normalized to the area of 1 cm{sup 2}, were V{sub oc} = 663 mV, J{sub sc} = 18.5 mA/cm{sup 2} and FF = 40%, respectively, corresponding to a total area conversion efficiency of {eta} = 5%. In cells of minor area (0.1 cm{sup 2}) efficiencies of 8% have been obtained. (author)

  7. Nano-Bio Electrochemical Interfacing-Linking Cell Biology and Micro-Electronics

    NASA Astrophysics Data System (ADS)

    Shacham-Diamand, Y.; Popovtzer, R.; Rishpon, Y.

    Integration of biological substance within electronic devices is an innovative and challenging area combining recent progress in molecular biology and micro technology. First, we introduce the concept of integrating living cells with Micro Electro Mechanical Systems (MEMS). Following a brief overview on "whole cell based biosensors" we describe the design, fabrication, and process of a biocompatible electrochemical "Lab-on-a-Chip" system. Demonstrating the application of electrochemical interfacing based whole cell bio chips, we present two different configurations: a. integration of prokaryotic cells (bacteria) for water toxicity detection, and b. integration of eukaryotic cells (human colon cancer cells) for rapid evaluation of the effectiveness of drug treatments. Both applications, with either microbes or mammalian cells integrated onto MEMS based biochips with liquid volume in the range of 100 nL-1 μL, function well and yield a detectable signal much higher than noise level after few minutes.

  8. MicroRNA-126 inhibits invasion in non-small cell lung carcinoma cell lines

    SciTech Connect

    Crawford, M.; Brawner, E.; Batte, K.; Yu, L.; Hunter, M.G.; Otterson, G.A.; Nuovo, G.; Marsh, C.B.; Nana-Sinkam, S.P.

    2008-09-05

    Crk is a member of a family of adaptor proteins that are involved in intracellular signal pathways altering cell adhesion, proliferation, and migration. Increased expression of Crk has been described in lung cancer and associated with increased tumor invasiveness. MicroRNAs (miRNAs) are a family of small non-coding RNAs (approximately 21-25 nt long) that are capable of targeting genes for either degradation of mRNA or inhibition of translation. Crk is a predicted putative target gene for miR-126. Over-expression of miR126 in a lung cancer cell line resulted in a decrease in Crk protein without any alteration in the associated mRNA. These lung cancer cells exhibit a decrease in adhesion, migration, and invasion. Decreased cancer cell invasion was also evident following targeted knockdown of Crk. MiR-126 alters lung cancer cell phenotype by inhibiting adhesion, migration, and invasion and the effects on invasion may be partially mediated through Crk regulation.

  9. Study of solid oxide fuel cell interconnects, protective coatings and advanced physical vapor deposition techniques

    NASA Astrophysics Data System (ADS)

    Gannon, Paul Edward

    High energy conversion efficiency, decreased environmentally-sensitive emissions and fuel flexibility have attracted increasing attention toward solid oxide fuel cell (SOFC) systems for stationary, transportation and portable power generation. Critical durability and cost issues, however, continue to impede wide-spread deployment. Many intermediate temperature (600-800°C) planar SOFC systems employ metallic alloy interconnect components, which physically connect individual fuel cells into electric series, facilitate gas distribution to appropriate SOFC electrode chambers (fuel/anode and oxidant[air]/cathode) and provide SOFC stack mechanical support. These demanding multifunctional requirements challenge commercially-available and inexpensive metallic alloys due to corrosion and related effects. Many ongoing investigations are aimed at enabling inexpensive metallic alloys (via bulk and/or surface modifications) as SOFC interconnects (SOFC(IC)s). In this study, two advanced physical vapor deposition (PVD) techniques: large area filtered vacuum arc deposition (LAFAD), and filtered arc plasma-assisted electron beam PVD (FA-EBPVD) were used to deposit a wide-variety of protective nanocomposite (amorphous/nanocrystalline) ceramic thin-film (<5microm) coatings on commercial and specialty stainless steels with different surface finishes. Both bare and coated steel specimens were subjected to SOFC(IC)-relevant exposures and evaluated using complimentary surface analysis techniques. Significant improvements were observed under simulated SOFC(IC) exposures with many coated specimens at ˜800°C relative to uncoated specimens: stable surface morphology; low area specific resistance (ASR <100mO·cm 2 >1,000 hours); and, dramatically reduced Cr volatility (>30-fold). Analyses and discussions of SOFC(IC) corrosion, advanced PVD processes and protective coating behavior are intended to advance understanding and accelerate the development of durable and commercially-viable SOFC

  10. Enthalpy of Vaporization and Vapor Pressures: An Inexpensive Apparatus

    ERIC Educational Resources Information Center

    Battino, Rubin; Dolson, David A.; Hall, Michael A.; Letcher, Trevor M.

    2007-01-01

    A simple and inexpensive method to determine the enthalpy of vaporization of liquids by measuring vapor pressure as a function of temperature is described. The vapor pressures measured with the stopcock cell were higher than the literature values and those measured with the sidearm rubber septum cell were both higher and lower than literature…

  11. Magnetic micro-device for manipulating PC12 cell migration and organization.

    PubMed

    Alon, N; Havdala, T; Skaat, H; Baranes, K; Marcus, M; Levy, I; Margel, S; Sharoni, A; Shefi, O

    2015-05-01

    Directing neuronal migration and growth has an important impact on potential post traumatic therapies. Magnetic manipulation is an advantageous method for remotely guiding cells. In the present study, we have generated highly localized magnetic fields with controllable magnetic flux densities to manipulate neuron-like cell migration and organization at the microscale level. We designed and fabricated a unique miniaturized magnetic device composed of an array of rectangular ferromagnetic bars made of permalloy (Ni80Fe20), sputter-deposited onto glass substrates. The asymmetric shape of the magnets enables one to design a magnetic landscape with high flux densities at the poles. Iron oxide nanoparticles were introduced into PC12 cells, making the cells magnetically sensitive. First, we manipulated the cells by applying an external magnetic field. The magnetic force was strong enough to direct PC12 cell migration in culture. Based on time lapse observations, we analysed the movement of the cells and estimated the amount of MNPs per cell. We plated the uploaded cells on the micro-patterned magnetic device. The cells migrated towards the high magnetic flux zones and aggregated at the edges of the patterned magnets, corroborating that the cells with magnetic nanoparticles are indeed affected by the micro-magnets and attracted to the bars' magnetic poles. Our study presents an emerging method for the generation of pre-programmed magnetic micro-'hot spots' to locate and direct cellular growth, setting the stage for implanted magnetic devices. PMID:25792133

  12. Micro-adhesion rings surrounding TCR microclusters are essential for T cell activation.

    PubMed

    Hashimoto-Tane, Akiko; Sakuma, Machie; Ike, Hiroshi; Yokosuka, Tadashi; Kimura, Yayoi; Ohara, Osamu; Saito, Takashi

    2016-07-25

    The immunological synapse (IS) formed at the interface between T cells and antigen-presenting cells represents a hallmark of initiation of acquired immunity. T cell activation is initiated at T cell receptor (TCR) microclusters (MCs), in which TCRs and signaling molecules assemble at the interface before IS formation. We found that each TCR-MC was transiently bordered by a ring structure made of integrin and focal adhesion molecules in the early phase of activation, which is similar in structure to the IS in microscale. The micro-adhesion ring is composed of LFA-1, focal adhesion molecules paxillin and Pyk2, and myosin II (MyoII) and is supported by F-actin core and MyoII activity through LFA-1 outside-in signals. The formation of the micro-adhesion ring was transient but especially sustained upon weak TCR stimulation to recruit linker for activation of T cells (LAT) and SLP76. Perturbation of the micro-adhesion ring induced impairment of TCR-MC development and resulted in impaired cellular signaling and cell functions. Thus, the synapse-like structure composed of the core TCR-MC and surrounding micro-adhesion ring is a critical structure for initial T cell activation through integrin outside-in signals. PMID:27354546

  13. Micro+nanotexturing of substrates to enhance ligand-assisted cancer cell isolation

    NASA Astrophysics Data System (ADS)

    Mahmood, Mohammed Arif I.; Wan, Yuan; Islam, Muhymin; Ali, Waqas; Hanif, Madiha; Kim, Young-tae; Iqbal, Samir M.

    2014-11-01

    This paper presents a simple approach to create a two-tiered surface for superior cancer cell isolation. The idea is inspired by the interactions of cells with a nanotextured basement membrane. The texture mimicked the extracellular matrix and basement membrane for superior target cell adhesion. Prepared micro+nanotextured surfaces showed enhanced cell capture. Preparation of the two-tiered surface was done using micro- and nanotexturing and was easily reproducible. It has been shown before that the larger surface area of a nanotextured surface assists the cell’s attachment through surface-anchored ligands. Taking it a step further, ligand functionalized two-level micro+nanotextured surfaces improved the sensitivity of the cancer cell isolation over simple flat nanotexturing. The isolation efficiency increased by 208% compared to the surface with a single-level nanotexture. The two-tiered surface was compatible with previously reported nanotextured devices used for cancer cell isolation. Micro-texture on the glass surface was created using simple sand gritting, followed by reactive ion etching (RIE) of the entire surface. The approach could create large surface areas within a short time while maintaining superior cell isolation efficiency.

  14. Flexible Electronics: High Pressure Chemical Vapor Deposition of Hydrogenated Amorphous Silicon Films and Solar Cells (Adv. Mater. 28/2016).

    PubMed

    He, Rongrui; Day, Todd D; Sparks, Justin R; Sullivan, Nichole F; Badding, John V

    2016-07-01

    On page 5939, J. V. Badding and co-workers describe the unrolling of a flexible hydrogenated amorphous silicon solar cell, deposited by high-pressure chemical vapor deposition. The high-pressure deposition process is represented by the molecules of silane infiltrating the small voids between the rolled up substrate, facilitating plasma-free deposition over a very large area. The high-pressure approach is expected to also find application for 3D nanoarchitectures. PMID:27442970

  15. Bidirectional Promoter Engineering for Single Cell MicroRNA Sensors in Embryonic Stem Cells

    PubMed Central

    Sladitschek, Hanna L.

    2016-01-01

    MicroRNAs have emerged as important markers and regulators of cell identity. Precise measurements of cellular miRNA levels rely traditionally on RNA extraction and thus do not allow to follow miRNA expression dynamics at the level of single cells. Non-invasive miRNA sensors present an ideal solution but they critically depend on the performance of suitable ubiquitous promoters that reliably drive expression both in pluripotent and differentiated cell types. Here we describe the engineering of bidirectional promoters that drive the expression of precise ratiometric fluorescent miRNA sensors in single mouse embryonic stem cells (mESCs) and their differentiated derivatives. These promoters are based on combinations of the widely used CAG, EF1α and PGK promoters as well as the CMV and PGK enhancers. miR-142-3p, which is known to be bimodally expressed in mESCs, served as a model miRNA to gauge the precision of the sensors. The performance of the resulting miRNA sensors was assessed by flow cytometry in single stable transgenic mESCs undergoing self-renewal or differentiation. EF1α promoters arranged back-to-back failed to drive the robustly correlated expression of two transgenes. Back-to-back PGK promoters were shut down during mESC differentiation. However, we found that a back-to-back arrangement of CAG promoters with four CMV enhancers provided both robust expression in mESCs undergoing differentiation and the best signal-to-noise for measurement of miRNA activity in single cells among all the sensors we tested. Such a bidirectional promoter is therefore particularly well suited to study the dynamics of miRNA expression during cell fate transitions at the single cell level. PMID:27152616

  16. Cancer Exosomes Perform Cell-Independent MicroRNA Biogenesis and Promote Tumorigenesis

    PubMed Central

    Melo, Sonia A.; Sugimoto, Hikaru; O’Connell, Joyce T.; Kato, Noritoshi; Villanueva, Alberto; Vidal, August; Qiu, Le; Vitkin, Edward; Perelman, Lev T.; Melo, Carlos A.; Lucci, Anthony; Ivan, Cristina; Calin, George A.; Kalluri, Raghu

    2014-01-01

    SUMMARY Exosomes are secreted by all cell types and contain proteins and nucleic acids. Here, we report that breast cancer associated exosomes contain microRNAs (miRNAs) associated with the RISC Loading Complex (RLC) and display cell-independent capacity to process precursor microRNAs (pre-miRNAs) into mature miRNAs. Pre-miRNAs, along with Dicer, AGO2, and TRBP, are present in exosomes of cancer cells. CD43 mediates the accumulation of Dicer specifically in cancer exosomes. Cancer exosomes mediate an efficient and rapid silencing of mRNAs to reprogram the target cell transcriptome. Exosomes derived from cells and sera of patients with breast cancer instigate non-tumorigenic epithelial cells to form tumors in a Dicer-dependent manner. These findings offer opportunities for the development of exosomes based biomarkers and therapies. PMID:25446899

  17. Customized homogenization and shaping of LED light by micro cells arrays

    NASA Astrophysics Data System (ADS)

    Asoubar, Daniel; Hellmann, Christian; Schweitzer, Hagen; Kuhn, Michael; Wyrowski, Frank

    2015-03-01

    The energy-efficient use of LED light requires the development of compact illumination systems for the customized homogenization and shaping of partially-coherent LED light. Therefore a design concept which is based on arrays of aperiodic micro structures, namely cells, for primary or secondary optics is introduced. Each cell of the array deflects locally the light into predefined directions and results in a light spot in the target plane. The light spots of all array cells together form the desired light pattern. The performance of three different cell geometries (linear gratings, micro prisms andmicromirrors) on the homogenization and shaping ofmonochromatic as well as white light LEDs is demonstrated. For the realistic evaluation of the illumination system an LED model including power spectrum, polarization, spatial and temporal coherence is chosen. Furthermore wave-optical effects like diffraction at the cell apertures are taken into account. For the grating cells arrays a rigorous analysis of the diffraction efficiencies is included.

  18. Cancer exosomes perform cell-independent microRNA biogenesis and promote tumorigenesis.

    PubMed

    Melo, Sonia A; Sugimoto, Hikaru; O'Connell, Joyce T; Kato, Noritoshi; Villanueva, Alberto; Vidal, August; Qiu, Le; Vitkin, Edward; Perelman, Lev T; Melo, Carlos A; Lucci, Anthony; Ivan, Cristina; Calin, George A; Kalluri, Raghu

    2014-11-10

    Exosomes are secreted by all cell types and contain proteins and nucleic acids. Here, we report that breast cancer associated exosomes contain microRNAs (miRNAs) associated with the RISC-Loading Complex (RLC) and display cell-independent capacity to process precursor microRNAs (pre-miRNAs) into mature miRNAs. Pre-miRNAs, along with Dicer, AGO2, and TRBP, are present in exosomes of cancer cells. CD43 mediates the accumulation of Dicer specifically in cancer exosomes. Cancer exosomes mediate an efficient and rapid silencing of mRNAs to reprogram the target cell transcriptome. Exosomes derived from cells and sera of patients with breast cancer instigate nontumorigenic epithelial cells to form tumors in a Dicer-dependent manner. These findings offer opportunities for the development of exosomes based biomarkers and therapies. PMID:25446899

  19. Hot-Wire Chemical Vapor Deposition Of Polycrystalline Silicon : From Gas Molecule To Solar Cell

    NASA Astrophysics Data System (ADS)

    van Veenendaal, P. A. T. T.

    2002-10-01

    Although the effort to investigate the use of renewable energy sources, such as wind and solar energy, has increased, their contribution to the total energy consumption remains insignificant. The conversion of solar energy into electricity through solar cells is one of the most promising techniques, but the use of these cells is limited by the high cost of electricity. The major contributions to these costs are the material and manufacturing costs. Over the past decades, the development of silicon based thin film solar cells has received much attention, because the fabrication costs are low. A promising material for use in thin film solar cells is polycrystalline silicon (poly-Si:H). A relatively new technique to deposit poly-Si:H is Hot-Wire Chemical Vapor Deposition (Hot-Wire CVD), in which the reactant gases are catalytically decomposed at the surface of a hot filament, mainly tungsten and tantalum. The main advantages of Hot-Wire CVD over PE-CVD are absence of ion bombardment, high deposition rate, low equipment cost and high gas utilization. This thesis deals with the full spectrum of deposition, characterization and application of poly-Si:H thin films, i.e. from gas molecule to solar cell. Studies on the decomposition of silane on the filament showed that the process is catalytic of nature and that silane is decomposed into Si and 4H. The dominant gas phase reaction is the reaction of Si and H with silane, resulting in SiH3, Si2H6, Si3H6 and H2SiSiH2. The film growth precursors are Si, SiH3 and Si2H4. Also, XPS results on used tantalum and tungsten filaments are discussed. The position dependent measurements show larger silicon contents at the ends of the tungsten filament, as compared to the middle, due to a lower filament temperature. This effect is insignificant for a tantalum filament. Deposition time dependent measurements show an increase in silicon content of the tungsten filament with time, while the silicon content on the tantalum filament saturates

  20. Gas/liquid sensing via chemotaxis of Euglena cells confined in an isolated micro-aquarium.

    PubMed

    Ozasa, Kazunari; Lee, Jeesoo; Song, Simon; Hara, Masahiko; Maeda, Mizuo

    2013-10-21

    We demonstrate on-chip gas/liquid sensing by using the chemotaxis of live bacteria (Euglena gracilis) confined in an isolated micro-aquarium, and gas/liquid permeation through porous polydimethylsiloxane (PDMS). The sensing chip consisted of one closed micro-aquarium and two separated bypass microchannels along the perimeter of the micro-aquarium. Test gas/liquid and reference samples were introduced into the two individual microchannels separately, and the gas/liquid permeated through the PDMS walls and dissolved in the micro-aquarium water, resulting in a chemical concentration gradient in the micro-aquarium. By employing the closed micro-aquarium isolated from sample flows, we succeeded in measuring the chemotaxis of Euglena for a gas substance quantitatively, which cannot be achieved with the conventional flow-type or hydro-gel-type microfluidic devices. We found positive (negative) chemotaxis for CO2 concentrations below (above) 15%, with 64 ppm as the minimum concentration affecting the cells. We also observed chemotaxis for ethanol and H2O2. By supplying culture medium via the microchannels, the Euglena culture remained alive for more than 2 months. The sensing chip is thus useful for culturing cells and using them for environmental toxicity/nutrition studies by monitoring their motion. PMID:23934095

  1. MicroRNA-Mediated Reprogramming of Somatic Cells into Induced Pluripotent Stem Cells.

    PubMed

    Sandmaier, Shelley E S; Telugu, Bhanu Prakash V L

    2015-01-01

    MicroRNAs or miRNAs belong to a class of small noncoding RNAs that play a crucial role in posttranscriptional regulation of gene expression. Nascent miRNAs are expressed as a longer transcript, which are then processed into a smaller 18-23-nucleotide mature miRNAs that bind to the target transcripts and induce cleavage or inhibit translation. MiRNAs therefore represent another key regulator of gene expression in establishing and maintaining unique cellular fate. Several classes of miRNAs have been identified to be uniquely expressed in embryonic stem cells (ESC) and regulated by the core transcription factors Oct4, Sox2, and Klf4. One such class of miRNAs is the mir-302/367 cluster that is enriched in pluripotent cells in vivo and in vitro. Using the mir-302/367 either by themselves or in combination with the Yamanaka reprogramming factors (Oct4, Sox2, c-Myc, and Klf4) has resulted in the establishment of induced pluripotent stem cells (iPSC) with high efficiencies. In this chapter, we outline the methodologies for establishing and utilizing the miRNA-based tools for reprogramming somatic cells into iPSC. PMID:26621586

  2. Dynamics of high Weber number drops impacting on hydrophobic surfaces with closed micro-cells.

    PubMed

    Zhang, Rui; Hao, Pengfei; Zhang, Xiwen; He, Feng

    2016-06-29

    The impact dynamics and bouncing performance of high Weber number drops on hydrophobic surfaces with open and closed micro-cells are investigated. Central wetted rings are observed on both closed-cell and open-cell surfaces under high Weber number collisions, which are proposed to constitute the key element affecting the bouncing behaviour. It is found that the drops rebound on closed-cell surfaces where the central area is in the "hybrid wetting state" at high Weber numbers, while the drops adhere to the open-cell surfaces where the central region is in the Wenzel state. A theoretical model is developed to explain this interesting phenomenon, in which the liquid cannot reach the bottom of the closed-cell hydrophobic surfaces since the air stored in micro-cavities prevents the sliding motion of the liquid film and functions as a "gas spring" lifting the liquid lamella. This indicates that the hydrophobic surface with simple micro cavities can maintain the water-repellent characteristics under drop impacts at high Weber numbers. These findings are expected to be crucial to a fundamental understanding of the rapid collisions between drops and micro-structured surfaces, as well as a valuable strategy to guide the fabrication of novel super water-repellant and anti-icing surfaces. PMID:27306824

  3. Effect of pervaporation plate thickness on the rate of methanol evaporation in a passive vapor-feed direct methanol fuel cell

    NASA Astrophysics Data System (ADS)

    Fauzi, N. F. I.; Hasran, U. A.; Kamarudin, S. K.

    2015-09-01

    In a passive vapor-feed direct methanol fuel cell (DMFC), methanol vapor is typically obtained using a pervaporation plate in a process by which liquid methanol contained in the fuel reservoir undergoes a phase change to vapor in the anodic vapor chamber. This work investigates the effect of pervaporation plate thickness on the rate of methanol evaporation using a three-dimensional simulation model developed by varying the plate thickness. A. The rate of methanol evaporation was measured using Darcy's law. The rate of methanol evaporation was found to be inversely proportional to the plate thickness, where the decrease in thickness inevitably lowers the resistance along the plate and consequently increases the methanol transport through the plate. This shows that the plate thickness has a significant influence on the rate of methanol evaporation and thereby plays an important role in improving the performance of the passive vapor-feed direct methanol fuel cell.

  4. Identification of microRNAs expressed highly in pancreatic islet-like cell clusters differentiated from human embryonic stem cells.

    PubMed

    Chen, Bo-Zhi; Yu, Sung-Liang; Singh, Sher; Kao, Li-Pin; Tsai, Zong-Yun; Yang, Pan-Chyr; Chen, Bai-Hsiun; Shoei-Lung Li, Steven

    2011-01-01

    Type 1 diabetes is an autoimmune destruction of pancreatic islet beta cell disease, making it important to find a new alternative source of the islet beta cells to replace the damaged cells. hES (human embryonic stem) cells possess unlimited self-renewal and pluripotency and thus have the potential to provide an unlimited supply of different cell types for tissue replacement. The hES-T3 cells with normal female karyotype were first differentiated into EBs (embryoid bodies) and then induced to generate the T3pi (pancreatic islet-like cell clusters derived from T3 cells), which expressed pancreatic islet cell-specific markers of insulin, glucagon and somatostatin. The expression profiles of microRNAs and mRNAs from the T3pi were analysed and compared with those of undifferentiated hES-T3 cells and differentiated EBs. MicroRNAs negatively regulate the expression of protein-coding mRNAs. The T3pi showed very high expression of microRNAs, miR-186, miR-199a and miR-339, which down-regulated the expression of LIN28, PRDM1, CALB1, GCNT2, RBM47, PLEKHH1, RBPMS2 and PAK6. Therefore, these microRNAs and their target genes are very likely to play important regulatory roles in the development of pancreas and/or differentiation of islet cells, and they may be manipulated to increase the proportion of beta cells and insulin synthesis in the differentiated T3pi for cell therapy of type I diabetics. PMID:20735361

  5. Specification of neural cell fate and regulation of neural stem cell proliferation by microRNAs

    PubMed Central

    Pham, Jacqueline T; Gallicano, G Ian

    2012-01-01

    In the approximately 20 years since microRNAs (miRNAs) were first characterized, they have been shown to play important roles in diverse physiologic functions, particularly those requiring coordinated changes in networks of signaling pathways. The ability of miRNAs to silence expression of multiple gene targets hints at complex connections that research has only begun to elucidate. The nervous system, particularly the brain, and its progenitor cells offer opportunities to examine miRNA function due to the myriad different cell types, numerous functionally distinct regions, and fluidly dynamic connections between them. This review aims to summarize current understanding of miRNA regulation in neurodevelopment, beginning with miRNAs that establish a general neural fate in cells. Particular attention is given to miR-124, the most abundant brain-specific miRNA, along with its key regulators and targets as an example of the potentially far-reaching effects of miRNAs. These modulators and mediators enable miRNAs to subtly calibrate cellular proliferation and differentiation. To better understand their mechanisms of action, miRNA profiles in distinct populations and regions of cells have been examined as well as miRNAs that regulate proliferation of stem cells, a process marked by dramatic morphological shifts in response to temporally subtle and refined shifts in gene expression. To tease out the complex interactions of miRNAs and stem cells more accurately, future studies will require more sensitive methods of assessing miRNA expression and more rigorous models of miRNA pathways. Thorough characterization of similarities and differences in specific miRNAs’ effects in different species is vital to developing better disease models and therapeutics using miRNAs. PMID:23671807

  6. Establishment of cells to monitor Microprocessor through fusion genes of microRNA and GFP

    SciTech Connect

    Tsutsui, Motomu; Hasegawa, Hitoki; Adachi, Koichi; Miyata, Maiko; Huang, Peng; Ishiguro, Naoki; Hamaguchi, Michinari; Iwamoto, Takashi

    2008-08-08

    Microprocessor, the complex of Drosha and DGCR8, promotes the processing of primary microRNA to precursor microRNA, which is a crucial step for microRNA maturation. So far, no convenient assay systems have been developed for observing this step in vivo. Here we report the establishment of highly sensitive cellular systems where we can visually monitor the function of Microprocessor. During a series of screening of transfectants with fusion genes of the EGFP cDNA and primary microRNA genes, we have obtained certain cell lines where introduction of siRNA against DGCR8 or Drosha strikingly augments GFP signals. In contrast, these cells have not responded to Dicer siRNA; thus they have a unique character that GFP signals should be negatively and specifically correlated to the action of Microprocessor among biogenesis of microRNA. These cell lines can be useful tools for real-time analysis of Microprocessor action in vivo and identifying its novel modulators.

  7. High-efficiency solar cells based on micro-nano scale structures

    NASA Astrophysics Data System (ADS)

    Dutta, Achyut K.; Olah, Robert; Mizuno, Genki; Sengupta, Rabi; Park, Jin-Hong; Wijewarnasuriya, Priyalal; Dhar, Nibir K.

    2010-04-01

    Higher efficiency solar cells are required to reduce solar array mass, stowed volume, and cost for numerous commercial and military applications. Conventional solar cell made of thin-film or crystal-Si (c-Si) or other thin films have limited conversion efficiency of 10 to 20% with the cost of 3-5/Wp. Current state-of-the-art crystalline multijunction solar cells are 30 % efficient with the cost of 30 to 40 /Wp. Increasing conversion efficiency of > 30% will enable to reduce the cost < $1/Wp and useful for various power platforms supporting mobile wireless, laptop, tent applications. Solar cell comprises with three dimensional blocks are shown to be higher conversion-efficiency than standard flat-type solar cell. Incorporating nano-scaled blocks in solar cell structures are shown to be increased performances due to (i) increase of the surface area to volume ratio, (ii) brining the junction closer to the carrier generation region which eliminate the carrier recombination , (iii) absorption of all incident photon flux, and (iv) broadening the absorption spectrum. Our activities on next generation high performance solar cells based on micro-nano scaled structures and various material systems will be presented. Details fabrication process of micro-nano scaled solar cell friendly to mass scale manufacturing will be also be described. We have achieved more than 20x optical performance enhancement for the solar cell based on micro-scaled structures, than that of flat-type (standard) solar cell, fabricated on the same Si substrate and same process. Simulation results showed that significant improvement in conversion efficiency more than 30% is possible for even c-Si solar cell based on the micro-nano scaled structures. Key issues and challenges for bringing it to the manufacturing will be discussed.

  8. MicroRNA-138 suppresses invasion and promotes apoptosis in head and neck squamous cell carcinoma cell lines

    PubMed Central

    Liu, Xiqiang; Jiang, Lu; Wang, Anxun; Yu, Jinsheng; Shi, Fei; Zhou, Xiaofeng

    2009-01-01

    Metastasis is a critical event in the progression of head and neck squamous cell carcinoma (HNSCC). To identify microRNAs associated with HNSCC metastasis, 6 paired HNSCC cell lines with different metastatic potential were examined. Using microarrays, a panel of differentially expressed microRNAs was identified, including reduction of miR-138 in highly metastatic cells. Ectopic transfection of miR-138 suppressed cell invasion and led to cell cycle arrest and apoptosis. Knockdown of miR-138 enhanced cell invasion and suppressed apoptosis. Thus, our results suggested miR-138 acts as a tumor suppresser and may serve as a therapeutic target for HNSCC patients at risk of metastasis. PMID:19540661

  9. Emerging Roles for MicroRNAs in T Follicular Helper Cell Differentiation.

    PubMed

    Maul, Julia; Baumjohann, Dirk

    2016-05-01

    T follicular helper (Tfh) cells are essential for the formation of germinal centers (GCs) and the development of long-lived humoral immunity. Tfh cell differentiation is a multistep process driven by the balanced expression of key transcription factors that form a regulatory network in which small changes in gene expression determine the Tfh cell fate decision. Here, we review recent findings that have revealed that certain microRNAs act as important mediators within this network, with roles in tuning gene expression. We integrate these findings into the current understanding of the mechanisms governing T helper cell differentiation, and propose a model in which the establishment of Tfh cell identity is dependent on the differential expression and concerted action of distinct microRNAs and transcription factors. PMID:27068008

  10. MicroRNA-491 regulates the proliferation and apoptosis of CD8+ T cells

    PubMed Central

    Yu, Ting; Zuo, Qian-Fei; Gong, Li; Wang, Li-Na; Zou, Quan-Ming; Xiao, Bin

    2016-01-01

    T lymphocyte-mediated immune responses are critical for antitumour immunity; however, T cell function is impaired in the tumour environment. MicroRNAs are involved in regulation of the immune system. While little is known about the function of intrinsic microRNAs in CD8+ T cells in the tumour microenvironment. Here, we found that miR-491 was upregulated in CD8+ T cells from mice with colorectal cancer. Retroviral overexpression of miR-491 in CD8+ and CD4+ T cells inhibited cell proliferation and promoted cell apoptosis and decreased the production of interferon-γ in CD8+ T cells. We found that miR-491 directly targeted cyclin-dependent kinase 4, the transcription factor T cell factor 1 and the anti-apoptotic protein B-cell lymphoma 2-like 1 in CD8+ T cells. Furthermore, tumour-derived TGF-β induced miR-491 expression in CD8+ T cells. Taken together, our results suggest that miR-491 can act as a negative regulator of T lymphocytes, especially CD8+ T cells, in the tumour environment; thus, this study provides a novel insight on dysfunctional CD8+ T cells during tumourigenesis and cancer progression. In conclusion, miR-491 may be a new target for antitumour immunotherapy. PMID:27484289

  11. Micro-Raman spectroscopy study of ALVAC virus infected chicken embryo cells

    NASA Astrophysics Data System (ADS)

    Misra, Anupam K.; Kamemoto, Lori E.; Hu, Ningjie; Dykes, Ava C.; Yu, Qigui; Zinin, Pavel V.; Sharma, Shiv K.

    2011-05-01

    Micro- Raman spectroscopic investigation of ALVAC virus and of normal chicken embryo fibroblast cells and the cells infected with ALVAC virus labeled with green fluorescence protein (GFP) were performed with a 785 nm laser. Good quality Micro-Raman spectra of the Alvac II virus were obtained. These spectra show that the ALVAC II virus contains buried tyrosine residues and the coat protein of the virus has α-helical structure. A comparison of Raman spectra of normal and virus infected chicken embryo fibroblast cells revealed that the virus infected cells show additional bands at 535, 928, and 1091 cm-1, respectively, corresponding to δ(C-O-C) glycosidic ring, protein α-helix, and DNA (O-P-O) modes. In addition, the tyrosine resonance double (833 and 855 cm-1) shows reversal in the intensity of the higher-frequency band as compared to the normal cells that can be used to identify the infected cells. In the C-H stretching region, the infected cells show bands with higher intensity as compared to that of the corresponding bands in the normal cells. We also found that the presence of GFP does not affect the Raman spectra of samples when using a 785 nm micro-Raman system because the green fluorescence wavelength of GFP is well below the Stokes-Raman shifted spectral region.

  12. Fabrication and characterization of a fuel flexible micro-reformer fully integrated in silicon for micro-solid oxide fuel cell applications

    NASA Astrophysics Data System (ADS)

    Pla, D.; Salleras, M.; Garbayo, I.; Morata, A.; Sabaté, N.; Divins, N. J.; Llorca, J.; Tarancón, A.

    2015-05-01

    A novel design of a fuel-flexible micro-reactor for hydrogen generation from ethanol and methane is proposed in this work. The micro-reactor is fully fabricated with mainstream MEMS technology and consists of an array of more than 20000 through-silicon vertically aligned micro-channels per cm2 of 50 μm in diameter. Due to this unique configuration, the micro-reformer presents a total surface per projected area of 16 cm2/cm2 and per volume of 320 cm2/cm3. The active surface of the micro-reformer, i.e. the walls of the micro-channels, is homogenously coated with a thin film of Rh- Pd/CeO2 catalyst. Excellent steam reforming of ethanol and dry reforming of methane are presented with hydrogen production rates above 3 mL/min·cm2 and hydrogen selectivity of ca. 50% on a dry basis at operations conditions suitable for application in micro-solid oxide fuel cells (micro-SOFCs), i.e. 700-800ºC and fuel flows of 0.02 mLL/min for ethanol and 36 mLG/min for methane (corresponding to a system able to produce one electrical watt).

  13. The expression and functional roles of microRNAs in stem cell differentiation.

    PubMed

    Shim, Jiwon; Nam, Jin-Wu

    2016-01-01

    microRNAs (miRNAs) are key regulators of cell state transition and retention during stem cell proliferation and differentiation by post-transcriptionally downregulating hundreds of conserved target genes via seed-pairing in their 3' untranslated region. In embryonic and adult stem cells, dozens of miRNAs that elaborately control stem cell processes by modulating the transcriptomic context therein have been identified. Some miRNAs accelerate the change of cell state into progenitor cell lineages-such as myoblast, myeloid or lymphoid progenitors, and neuro precursor stem cells-and other miRNAs decelerate the change but induce proliferative activity, resulting in cell state retention. This cell state choice can be controlled by endogenously or exogenously changing miRNA levels or by including or excluding target sites. This control of miRNA-mediated gene regulation could improve our understanding of stem cell biology and facilitate their development as therapeutic tools. PMID:26497582

  14. Imaging and manipulating the structural machinery of living cells on the micro- and nanoscale

    PubMed Central

    Chown, Matthew G; Kumar, Sanjay

    2007-01-01

    The structure, physiology, and fate of living cells are all highly sensitive to mechanical forces in the cellular microenvironment, including stresses and strains that originate from encounters with the extracellular matrix (ECM), blood and other flowing materials, and neighbouring cells. This relationship between context and physiology bears tremendous implications for the design of cellular micro-or nanotechnologies, since any attempt to control cell behavior in a device must provide the appropriate physical microenvironment for the desired cell behavior. Cells sense, process, and respond to biophysical cues in their environment through a set of integrated, multi-scale structural complexes that span length scales from single molecules to tens of microns, including small clusters of force-sensing molecules at the cell surface, micron-sized cell-ECM focal adhesion complexes, and the cytoskeleton that permeates and defines the entire cell. This review focuses on several key technologies that have recently been developed or adapted for the study of the dynamics of structural micro-and nanosystems in living cells and how these systems contribute to spatially-and temporally-controlled changes in cellular structure and mechanics. We begin by discussing subcellular laser ablation, which permits the precise incision of nanoscale structural elements in living cells in order to discern their mechanical properties and contributions to cell structure. We then discuss fluorescence recovery after photobleaching and fluorescent speckle microscopy, two live-cell fluorescence imaging methods that enable quantitative measurement of the binding and transport properties of specific proteins in the cell. Finally, we discuss methods to manipulate cellular structural networks by engineering the extracellular environment, including microfabrication of ECM distributions of defined geometry and microdevices designed to measure cellular traction forces at micron-scale resolution. Together

  15. DNA Translocation and Cell Electroporation in Micro and Nanofluidic Devices

    NASA Astrophysics Data System (ADS)

    Gupta, Cherry

    The cell membrane is made of a thin (˜ 5nm) lipid bilayer which serves as an effective insulator and diffusion barrier for entities external to the cell from entering the cell. However, for research, diagnostic and therapeutic purposes, there is a need to deliver molecules of interest to the interior of live cells. This is usually accomplished by two methods: (a) carrier mediated delivery which consists of encapsulating the gene/molecule of interest either in an empty viral capsid or in chemically formulated lipoplex or polyplex nanoparticles, or (b) physical methods of delivery, which include the use of different kinds of forces to create reversible pores on the cell membrane (sonoporation, electroporation) or directly inject molecules to the cell cytosol (Gene Gun, microinjection). Of the aforementioned techniques, electroporation is the most commonly used due to it simplicity and ease of use. Our group recently demonstrated a nanochannel based electroporation (NEP) technique, in which two microchannels (˜40 m diameter) are connected by a nanochannel (˜ 200-400 mum diameter) in the center. A cell is positioned in one microchannel such that it makes contact with the nanochannel and transfection agents are placed in the other microchannel. An external electric field applied across the device locally porates the cell where it touches the nancohannel and drives the transfection agents into the cell. Besides maintaining high cell viability and achieving dose control, an important feature of NEP is the delivery of large molecules such as plasmids and quantum dots directly into the cell cytosol. In contrast, delivery of large plasmids during bulk electroporation, wherein cells and genes/plasmids are mixed in a buffered medium and an external electric field is applied across the mixture which electroporates the cells, is via formation of cell membrane bound aggregates which get endocytosed post pulsation. Various mechanisms of DNA transport across the membrane have

  16. Therapeutic antagonists of microRNAs deplete leukemia-initiating cell activity

    PubMed Central

    Velu, Chinavenmeni S.; Chaubey, Aditya; Phelan, James D.; Horman, Shane R.; Wunderlich, Mark; Guzman, Monica L.; Jegga, Anil G.; Zeleznik-Le, Nancy J.; Chen, Jianjun; Mulloy, James C.; Cancelas, Jose A.; Jordan, Craig T.; Aronow, Bruce J.; Marcucci, Guido; Bhat, Balkrishen; Gebelein, Brian; Grimes, H. Leighton

    2013-01-01

    Acute myelogenous leukemia (AML) subtypes that result from oncogenic activation of homeobox (HOX) transcription factors are associated with poor prognosis. The HOXA9 transcription activator and growth factor independent 1 (GFI1) transcriptional repressor compete for occupancy at DNA-binding sites for the regulation of common target genes. We exploited this HOXA9 versus GFI1 antagonism to identify the genes encoding microRNA-21 and microRNA-196b as transcriptional targets of HOX-based leukemia oncoproteins. Therapeutic inhibition of microRNA-21 and microRNA-196b inhibited in vitro leukemic colony forming activity and depleted in vivo leukemia-initiating cell activity of HOX-based leukemias, which led to leukemia-free survival in a murine AML model and delayed disease onset in xenograft models. These data establish microRNA as functional effectors of endogenous HOXA9 and HOX-based leukemia oncoproteins, provide a concise in vivo platform to test RNA therapeutics, and suggest therapeutic value for microRNA antagonists in AML. PMID:24334453

  17. Microfluidic Buffer Exchange for Interference-free Micro/Nanoparticle Cell Engineering.

    PubMed

    Tay, Hui Min; Yeo, David C; Wiraja, Christian; Xu, Chenjie; Hou, Han Wei

    2016-01-01

    Engineering cells with active-ingredient-loaded micro/nanoparticles (NPs) is becoming an increasingly popular method to enhance native therapeutic properties, enable bio imaging and control cell phenotype. A critical yet inadequately addressed issue is the significant number of particles that remain unbound after cell labeling which cannot be readily removed by conventional centrifugation. This leads to an increase in bio imaging background noise and can impart transformative effects onto neighboring non-target cells. In this protocol, we present an inertial microfluidics-based buffer exchange strategy termed as Dean Flow Fractionation (DFF) to efficiently separate labeled cells from free NPs in a high throughput manner. The developed spiral microdevice facilitates continuous collection (>90% cell recovery) of purified cells (THP-1 and MSCs) suspended in new buffer solution, while achieving >95% depletion of unbound fluorescent dye or dye-loaded NPs (silica or PLGA). This single-step, size-based cell purification strategy enables high cell processing throughput (10(6) cells/min) and is highly useful for large-volume cell purification of micro/nanoparticle engineered cells to achieve interference-free clinical application. PMID:27500904

  18. Genome-Wide CRISPR-Cas9 Screen Identifies MicroRNAs That Regulate Myeloid Leukemia Cell Growth

    PubMed Central

    Wallace, Jared; Hu, Ruozhen; Mosbruger, Timothy L.; Dahlem, Timothy J.; Stephens, W. Zac; Rao, Dinesh S.; Round, June L.; O’Connell, Ryan M.

    2016-01-01

    Mammalian microRNA expression is dysregulated in human cancer. However, the functional relevance of many microRNAs in the context of tumor biology remains unclear. Using CRISPR-Cas9 technology, we performed a global loss-of-function screen to simultaneously test the functions of individual microRNAs and protein-coding genes during the growth of a myeloid leukemia cell line. This approach identified evolutionarily conserved human microRNAs that suppress or promote cell growth, revealing that microRNAs are extensively integrated into the molecular networks that control tumor cell physiology. miR-155 was identified as a top microRNA candidate promoting cellular fitness, which we confirmed with two distinct miR-155-targeting CRISPR-Cas9 lentiviral constructs. Further, we performed anti-correlation functional profiling to predict relevant microRNA-tumor suppressor gene or microRNA-oncogene interactions in these cells. This analysis identified miR-150 targeting of p53, a connection that was experimentally validated. Taken together, our study describes a powerful genetic approach by which the function of individual microRNAs can be assessed on a global level, and its use will rapidly advance our understanding of how microRNAs contribute to human disease. PMID:27081855

  19. MicroRNA-497 impairs the growth of chemoresistant neuroblastoma cells by targeting cell cycle, survival and vascular permeability genes

    PubMed Central

    Soriano, Aroa; París-Coderch, Laia; Jubierre, Luz; Martínez, Alba; Zhou, Xiangyu; Piskareva, Olga; Bray, Isabella; Vidal, Isaac; Almazán-Moga, Ana; Molist, Carla; Roma, Josep; Bayascas, José R.; Casanovas, Oriol; Stallings, Raymond L.; de Toledo, José Sánchez; Gallego, Soledad; Segura, Miguel F.

    2016-01-01

    Despite multimodal therapies, a high percentage of high-risk neuroblastoma (NB) become refractory to current treatments, most of which interfere with cell cycle and DNA synthesis or function, activating the DNA damage response (DDR). In cancer, this process is frequently altered by deregulated expression or function of several genes which contribute to multidrug resistance (MDR). MicroRNAs are outstanding candidates for therapy since a single microRNA can modulate the expression of multiple genes of the same or different pathways, thus hindering the development of resistance mechanisms by the tumor. We found several genes implicated in the MDR to be overexpressed in high-risk NB which could be targeted by microRNAs simultaneously. Our functional screening identified several of those microRNAs that reduced proliferation of chemoresistant NB cell lines, the best of which was miR-497. Low expression of miR-497 correlated with poor patient outcome. The overexpression of miR-497 reduced the proliferation of multiple chemoresistant NB cell lines and induced apoptosis in MYCN-amplified cell lines. Moreover, the conditional expression of miR-497 in NB xenografts reduced tumor growth and inhibited vascular permeabilization. MiR-497 targets multiple genes related to the DDR, cell cycle, survival and angiogenesis, which renders this molecule a promising candidate for NB therapy. PMID:26824183

  20. Micro FT-IR Characterization Of Human Lung Tumor Cells

    NASA Astrophysics Data System (ADS)

    Benedetti, Enzo; Teodori, L.; Vergamini, Piergiorgio; Trinca, M. L.; Mauro, F.; Salvati, F.; Spremolla, Giuliano

    1989-12-01

    FT-IR spectroscopy has opened up a new approach to the analytical study of cell transformation. Investigations carried out in normal and leukemic lymphocytes have evidenced an increase in DNA with respect to proteic components in neoplastic cells.(1) The evaluation of the ratio of the integrated areas(A) of the bands at 1080 cm-1 (mainly DNA) and at 1540 cm-1 (proteic components) has allowed us to establish a parameter which indicates, for values above 1.5, the neoplastic nature of cells. Recently, this approach has been applied to the study of human lung tumor cells. Several monocellular suspension procedures of the tissue fragment (mechanical and/or chemical) were tested to obtain reproducible and reliable spectra able to differentiate clearly between normal and patological cells. Chemical treatment (EDTA, Pepsin, Collagenase, etc.) produced additional bands in the spectra of the cells causing distortion of the profiles of some absorptions, and as a result, mechanical treatment was preferred. The normal and neoplastic cells homogeneously distributed by cytospin preparation on BaF2 windows were examined by means of FT-IR microscopy. An examination of several microareas of each sample yielded reproducible spectra, with values of the A 1080 cm-1 / A 1540 cm-1 parameter within a very narrow range for each sample, even if certain differences still remained among the different cases, in good agreement with the results obtained for leukemic cells.(1) The value of this parameter was found to be lower for cells isolated from the normal area of lung, than in the case of those corresponding to the tumoral area, meaning that an increase occurs in DNA with respect to the proteic components. These insights, which provide a basis to obtain indications at the molecular level, can open up new possibilities in clinical practice, in order to obtain diagnosis confirmation, to detect early stages of disease and to offer additional indications in cases of dubious interpretation.

  1. Extracellular microvesicle microRNAs in children with sickle cell anaemia with divergent clinical phenotypes.

    PubMed

    Khalyfa, Abdelnaby; Khalyfa, Ahamed A; Akbarpour, Mahzad; Connes, Phillippe; Romana, Marc; Lapping-Carr, Gabrielle; Zhang, Chunling; Andrade, Jorge; Gozal, David

    2016-09-01

    Sickle cell anaemia (SCA) is the most frequent genetic haemoglobinopathy, which exhibits a highly variable clinical course characterized by hyper-coagulable and pro-inflammatory states, as well as endothelial dysfunction. Extracellular microvesicles are released into biological fluids and play a role in modifying the functional phenotype of target cells. We hypothesized that potential differences in plasma-derived extracellular microvesicles (EV) function and cargo from SCA patients may underlie divergent clinical trajectories. Plasma EV from SCA patients with mild, intermediate and severe clinical disease course were isolated, and primary endothelial cell cultures were exposed. Endothelial cell activation, monocyte adhesion, barrier disruption and exosome cargo (microRNA microarrays) were assessed. EV disrupted the endothelial barrier and induced expression of adhesion molecules and monocyte adhesion in a SCA severity-dependent manner compared to healthy children. Microarray approaches identified a restricted signature of exosomal microRNAs that readily distinguished severe from mild SCA, as well as from healthy children. The microRNA candidates were further validated using quantitative real time polymerase chain reaction assays, and revealed putative gene targets. Circulating exosomal microRNAs may play important roles in predicting the clinical course of SCA, and in delineation of individually tailored, mechanistically-based clinical treatment approaches of SCA patients in the near future. PMID:27161653

  2. Telocytes transfer extracellular vesicles loaded with microRNAs to stem cells

    PubMed Central

    Cismasiu, Valeriu B; Popescu, Laurentiu M

    2015-01-01

    Telocytes (TCs) are cells ubiquitously distributed in the body and characterized by very long and thin prolongations named telopodes (Tps). Cardiac TCs are the best characterized TCs for the moment. Tps release extracellular vesicles (EVs) in vivo and in vitro suggesting that TCs regulate the activity of other cells by vesicular paracrine signals. TCs have been found within the stem cell niche of several organs. Electron microscopy or electron tomography has shown that Tps are located in close vicinity of stem cells (SC). Since stem cell regulation by niche components involves paracrine signalling, we have investigated if TCs could be part of this mechanism. Using fluorescent labelling of cells and EVs with calcein and Cy5-miR-21 oligos, we provide evidence that TCs can modulate SC through EVs loaded with microRNAs. TCs deliver microRNA to cardiac stem cells (CSCs), as well as to other types of SCs (e.g. hematopoietic SC) indicating that this mechanism is not restricted to cardiac tissue. We also found that CSCs deliver microRNA loaded EVs to TCs, suggesting that there is a continuous, post-transcriptional regulatory signal back and forth between TCs and SC. In conclusion, our data reveal the existence of a reciprocal (bidirectional) epigenetic signalling between TCs and SC. PMID:25600068

  3. Numerical modelling of methane-powered micro-tubular, single-chamber solid oxide fuel cell

    NASA Astrophysics Data System (ADS)

    Akhtar, N.; Decent, S. P.; Kendall, K.

    An experimentally validated, two-dimensional, axisymmetric, numerical model of micro-tubular, single-chamber solid oxide fuel cell (MT-SC-SOFC) has been developed. The model incorporates methane full combustion, steam reforming, dry reforming and water-gas shift reaction followed by electrochemical oxidation of produced hydrogen within the anode. On the cathode side, parasitic combustion of methane along with the electrochemical oxygen reduction is implemented. The results show that the poor performance of single-chamber SOFC as compared to the conventional (dual-chamber) SOFC (in case of micro-tubes) is due to the mass transport limitation on the anode side. The gas velocity inside the micro-tube is far too low when compared to the gas-chamber inlet velocity. The electronic current density is also non-uniform over the cell length, mainly due to the short length of the anode current collector located at the cell outlet. Furthermore, the higher temperature near the cell edges is due to the methane combustion (very close to the cell inlet) and current collection point (at the cell outlet). Both of these locations could be sensitive to the silver current collecting wire as silver may rupture due to cell overheating.

  4. Deep sequencing reveals abundant noncanonical retroviral microRNAs in B-cell leukemia/lymphoma.

    PubMed

    Rosewick, Nicolas; Momont, Mélanie; Durkin, Keith; Takeda, Haruko; Caiment, Florian; Cleuter, Yvette; Vernin, Céline; Mortreux, Franck; Wattel, Eric; Burny, Arsène; Georges, Michel; Van den Broeke, Anne

    2013-02-01

    Viral tumor models have significantly contributed to our understanding of oncogenic mechanisms. How transforming delta-retroviruses induce malignancy, however, remains poorly understood, especially as viral mRNA/protein are tightly silenced in tumors. Here, using deep sequencing of broad windows of small RNA sizes in the bovine leukemia virus ovine model of leukemia/lymphoma, we provide in vivo evidence of the production of noncanonical RNA polymerase III (Pol III)-transcribed viral microRNAs in leukemic B cells in the complete absence of Pol II 5'-LTR-driven transcriptional activity. Processed from a cluster of five independent self-sufficient transcriptional units located in a proviral region dispensable for in vivo infectivity, bovine leukemia virus microRNAs represent ∼40% of all microRNAs in both experimental and natural malignancy. They are subject to strong purifying selection and associate with Argonautes, consistent with a critical function in silencing of important cellular and/or viral targets. Bovine leukemia virus microRNAs are strongly expressed in preleukemic and malignant cells in which structural and regulatory gene expression is repressed, suggesting a key role in tumor onset and progression. Understanding how Pol III-dependent microRNAs subvert cellular and viral pathways will contribute to deciphering the intricate perturbations that underlie malignant transformation. PMID:23345446

  5. Development of a micro flow-through cell for high field NMR spectroscopy.

    SciTech Connect

    Alam, Todd Michael; McIntyre, Sarah K.

    2011-05-01

    A highly transportable micro flow-through detection cell for nuclear magnetic resonance (NMR) spectroscopy has been designed, fabricated and tested. This flow-through cell allows for the direct coupling between liquid chromatography (LC) and gel permeation chromatography (GPC) resulting in the possibility of hyphenated LC-NMR and GPC-NMR. The advantage of the present flow cell design is that it is independent and unconnected to the detection probe electronics, is compatible with existing commercial high resolution NMR probes, and as such can be easily implemented at any NMR facility. Two different volumes were fabricated corresponding to between {approx}3.8 and 10 {micro}L detection volume. Examples of the performance of the cell on different NMR instruments, and using different NMR detection probes were demonstrated.

  6. Micro-electro-mechanical systems phosphoric acid fuel cell

    DOEpatents

    Sopchak, David A.; Morse, Jeffrey D.; Upadhye, Ravindra S.; Kotovsky, Jack; Graff, Robert T.

    2010-08-17

    A phosphoric acid fuel cell system comprising a porous electrolyte support, a phosphoric acid electrolyte in the porous electrolyte support, a cathode electrode contacting the phosphoric acid electrolyte, and an anode electrode contacting the phosphoric acid electrolyte.

  7. Micro-electro-mechanical systems phosphoric acid fuel cell

    DOEpatents

    Sopchak, David A.; Morse, Jeffrey D.; Upadhye, Ravindra S.; Kotovsky, Jack; Graff, Robert T.

    2010-12-21

    A phosphoric acid fuel cell system comprising a porous electrolyte support, a phosphoric acid electrolyte in the porous electrolyte support, a cathode electrode contacting the phosphoric acid electrolyte, and an anode electrode contacting the phosphoric acid electrolyte.

  8. Taxane recovery from cells of Taxus in micro- and hypergravity

    NASA Technical Reports Server (NTRS)

    Durzan, D. J.; Ventimiglia, F.; Havel, L.

    1998-01-01

    Cell suspension cultures of Taxus cuspidata produce taxanes that are released from the outer surface of cells into the culture medium as free and bound alkaloids. Paclitaxel (Taxol (TM)), is an anti-cancer drug in short supply. It has a taxane ring derived from baccatin III and a C-13 phenylisoserine side-chain. This drug is produced over a wide range of gravitational forces. Monoclonal and polyclonal antibodies to paclitaxel, baccatin III, and the C-13 phenylisoserine side chain were combined in multiple-labeling studies to localize taxanes and paclitaxel on cell surfaces or on particles released into the culture medium. Bioreactor vessel design altered the composition of taxanes recovered from cells in simulated microgravity. At 10(-2) and 2x10(-4)g, taxane recovery was reduced but biomass growth and percent paclitaxel was significantly increased. At 1 to 24g, growth was reduced with a significant recovery of total taxanes with low percent paclitaxel. Bound paclitaxel was also localized in endonuclease-rich fragmenting nuclei of individual apoptotic cells. A model is presented comprising TCH (touch) genes encoding enzymes that modify taxane-bearing xylan residues in cell walls, the calcium-sensing of gravitational forces by the cytoplasm, and the predisposition of nuclei to apoptosis. This integrates the adaptive physiological and biochemical responses of drug-producing genomes with gravitational forces.

  9. Measuring the mechanical properties of plant cells by combining micro-indentation with osmotic treatments

    PubMed Central

    Weber, Alain; Braybrook, Siobhan; Huflejt, Michal; Mosca, Gabriella; Routier-Kierzkowska, Anne-Lise; Smith, Richard S.

    2015-01-01

    Growth in plants results from the interaction between genetic and signalling networks and the mechanical properties of cells and tissues. There has been a recent resurgence in research directed at understanding the mechanical aspects of growth, and their feedback on genetic regulation. This has been driven in part by the development of new micro-indentation techniques to measure the mechanical properties of plant cells in vivo. However, the interpretation of indentation experiments remains a challenge, since the force measures results from a combination of turgor pressure, cell wall stiffness, and cell and indenter geometry. In order to interpret the measurements, an accurate mechanical model of the experiment is required. Here, we used a plant cell system with a simple geometry, Nicotiana tabacum Bright Yellow-2 (BY-2) cells, to examine the sensitivity of micro-indentation to a variety of mechanical and experimental parameters. Using a finite-element mechanical model, we found that, for indentations of a few microns on turgid cells, the measurements were mostly sensitive to turgor pressure and the radius of the cell, and not to the exact indenter shape or elastic properties of the cell wall. By complementing indentation experiments with osmotic experiments to measure the elastic strain in turgid cells, we could fit the model to both turgor pressure and cell wall elasticity. This allowed us to interpret apparent stiffness values in terms of meaningful physical parameters that are relevant for morphogenesis. PMID:25873663

  10. An Integrative Analysis of microRNA and mRNA Profiling in CML Stem Cells.

    PubMed

    Nassar, Farah J; El Eit, Rabab; Nasr, Rihab

    2016-01-01

    Integrative analysis of microRNA (miRNA) and messenger RNA (mRNA) in Chronic Myeloid leukemia (CML) stem cells is an important technique to study the involvement of miRNA and their targets in CML stem cells self-renewal, maintenance, and therapeutic resistance. Here, we describe a simplified integrative analysis using Ingenuity Pathway Analysis software after performing proper RNA extraction, miRNA and mRNA microarray and data analysis. PMID:27581151

  11. High-efficiency organometallic vapor phase epitaxy AlGaAs/GaAs monolithic cascade solar cell using metal interconnects

    SciTech Connect

    Ludowise, M.J.; LaRue, R.A.; Borden, P.G.; Gregory, P.E.; Dietze, W.T.

    1982-09-15

    A two-junction solar cell has been fabricated using an Al/sub 0.30/Ga/sub 0.70/As (1.82 eV) tap cell and a GaAs (1.43 eV) bottom cell. A processed metal interconnect is used to connect the two cells together in series. An efficiency of 21.5% at 980 mW/cm/sup 2/ has been measured in a solar simulator with an open circuit voltage of 2.35 V, a short circuit current of 118.6 mA/cm/sup 2/, and a fill factor of 0.76. An efficiency of 22% has been measured under 130 AM3 sun in a solar tracking concentrator. Organometallic vapor phase epitaxy is used to grow the entire nine-layer device.

  12. Co-culture of vascular endothelial cells and smooth muscle cells by hyaluronic acid micro-pattern on titanium surface

    NASA Astrophysics Data System (ADS)

    Li, Jingan; Li, Guicai; Zhang, Kun; Liao, Yuzhen; Yang, Ping; Maitz, Manfred F.; Huang, Nan

    2013-05-01

    Micro-patterning as an effective bio-modification technique is increasingly used in the development of biomaterials with superior mechanical and biological properties. However, as of now, little is known about the simultaneous regulation of endothelial cells (EC) and smooth muscle cells (SMC) by cardiovascular implants. In this study, a co-culture system of EC and SMC was built on titanium surface by the high molecular weight hyaluronic acid (HMW-HA) micro-pattern. Firstly, the micro-pattern sample with a geometry of 25 μm wide HMW-HA ridges, and 25 μm alkali-activated Ti grooves was prepared by microtransfer molding (μTM) for regulating SMC morphology. Secondly, hyaluronidase was used to decompose high molecular weight hyaluronic acid into low molecular weight hyaluronic acid which could promote EC adhesion. Finally, the morphology of the adherent EC was elongated by the SMC micro-pattern. The surface morphology of the patterned Ti was imaged by SEM. The existence of high molecular weight hyaluronic acid on the modified Ti surface was demonstrated by FTIR. The SMC micro-pattern and EC/SMC co-culture system were characterized by immunofluorescence microscopy. The nitric oxide release test and cell retention calculation were used to evaluate EC function on inhibiting hyperplasia and cell shedding, respectively. The results indicate that EC in EC/SMC co-culture system displayed a higher NO release and cell retention compared with EC cultured alone. It can be suggested that the EC/SMC co-culture system possessed superiority to EC cultured alone in inhibiting hyperplasia and cell shedding at least in a short time of 24 h.

  13. Constrained Vapor Bubble

    NASA Technical Reports Server (NTRS)

    Huang, J.; Karthikeyan, M.; Plawsky, J.; Wayner, P. C., Jr.

    1999-01-01

    The nonisothermal Constrained Vapor Bubble, CVB, is being studied to enhance the understanding of passive systems controlled by interfacial phenomena. The study is multifaceted: 1) it is a basic scientific study in interfacial phenomena, fluid physics and thermodynamics; 2) it is a basic study in thermal transport; and 3) it is a study of a heat exchanger. The research is synergistic in that CVB research requires a microgravity environment and the space program needs thermal control systems like the CVB. Ground based studies are being done as a precursor to flight experiment. The results demonstrate that experimental techniques for the direct measurement of the fundamental operating parameters (temperature, pressure, and interfacial curvature fields) have been developed. Fluid flow and change-of-phase heat transfer are a function of the temperature field and the vapor bubble shape, which can be measured using an Image Analyzing Interferometer. The CVB for a microgravity environment, has various thin film regions that are of both basic and applied interest. Generically, a CVB is formed by underfilling an evacuated enclosure with a liquid. Classification depends on shape and Bond number. The specific CVB discussed herein was formed in a fused silica cell with inside dimensions of 3x3x40 mm and, therefore, can be viewed as a large version of a micro heat pipe. Since the dimensions are relatively large for a passive system, most of the liquid flow occurs under a small capillary pressure difference. Therefore, we can classify the discussed system as a low capillary pressure system. The studies discussed herein were done in a 1-g environment (Bond Number = 3.6) to obtain experience to design a microgravity experiment for a future NASA flight where low capillary pressure systems should prove more useful. The flight experiment is tentatively scheduled for the year 2000. The SCR was passed on September 16, 1997. The RDR is tentatively scheduled for October, 1998.

  14. Measuring spatial variability of vapor flux to characterize vadose-zone VOC sources: Flow-cell experiments

    NASA Astrophysics Data System (ADS)

    Mainhagu, J.; Morrison, C.; Truex, M.; Oostrom, M.; Brusseau, M. L.

    2014-10-01

    A method termed vapor-phase tomography has recently been proposed to characterize the distribution of volatile organic contaminant mass in vadose-zone source areas, and to measure associated three-dimensional distributions of local contaminant mass discharge. The method is based on measuring the spatial variability of vapor flux, and thus inherent to its effectiveness is the premise that the magnitudes and temporal variability of vapor concentrations measured at different monitoring points within the interrogated area will be a function of the geospatial positions of the points relative to the source location. A series of flow-cell experiments was conducted to evaluate this premise. A well-defined source zone was created by injection and extraction of a non-reactive gas (SF6). Spatial and temporal concentration distributions obtained from the tests were compared to simulations produced with a mathematical model describing advective and diffusive transport. Tests were conducted to characterize both areal and vertical components of the application. Decreases in concentration over time were observed for monitoring points located on the opposite side of the source zone from the local-extraction point, whereas increases were observed for monitoring points located between the local-extraction point and the source zone. The results illustrate that comparison of temporal concentration profiles obtained at various monitoring points gives a general indication of the source location with respect to the extraction and monitoring points.

  15. Measuring Spatial Variability of Vapor Flux to Characterize Vadose-zone VOC Sources: Flow-cell Experiments

    SciTech Connect

    Mainhagu, Jon; Morrison, C.; Truex, Michael J.; Oostrom, Martinus; Brusseau, Mark

    2014-08-05

    A method termed vapor-phase tomography has recently been proposed to characterize the distribution of volatile organic contaminant mass in vadose-zone source areas, and to measure associated three-dimensional distributions of local contaminant mass discharge. The method is based on measuring the spatial variability of vapor flux, and thus inherent to its effectiveness is the premise that the magnitudes and temporal variability of vapor concentrations measured at different monitoring points within the interrogated area will be a function of the geospatial positions of the points relative to the source location. A series of flow-cell experiments was conducted to evaluate this premise. A well-defined source zone was created by injection and extraction of a non-reactive gas (SF6). Spatial and temporal concentration distributions obtained from the tests were compared to simulations produced with a mathematical model describing advective and diffusive transport. Tests were conducted to characterize both areal and vertical components of the application. Decreases in concentration over time were observed for monitoring points located on the opposite side of the source zone from the local–extraction point, whereas increases were observed for monitoring points located between the local–extraction point and the source zone. We found that the results illustrate that comparison of temporal concentration profiles obtained at various monitoring points gives a general indication of the source location with respect to the extraction and monitoring points.

  16. Measuring Spatial Variability of Vapor Flux to Characterize Vadose-zone VOC Sources: Flow-cell Experiments

    DOE PAGESBeta

    Mainhagu, Jon; Morrison, C.; Truex, Michael J.; Oostrom, Martinus; Brusseau, Mark

    2014-08-05

    A method termed vapor-phase tomography has recently been proposed to characterize the distribution of volatile organic contaminant mass in vadose-zone source areas, and to measure associated three-dimensional distributions of local contaminant mass discharge. The method is based on measuring the spatial variability of vapor flux, and thus inherent to its effectiveness is the premise that the magnitudes and temporal variability of vapor concentrations measured at different monitoring points within the interrogated area will be a function of the geospatial positions of the points relative to the source location. A series of flow-cell experiments was conducted to evaluate this premise. Amore » well-defined source zone was created by injection and extraction of a non-reactive gas (SF6). Spatial and temporal concentration distributions obtained from the tests were compared to simulations produced with a mathematical model describing advective and diffusive transport. Tests were conducted to characterize both areal and vertical components of the application. Decreases in concentration over time were observed for monitoring points located on the opposite side of the source zone from the local–extraction point, whereas increases were observed for monitoring points located between the local–extraction point and the source zone. We found that the results illustrate that comparison of temporal concentration profiles obtained at various monitoring points gives a general indication of the source location with respect to the extraction and monitoring points.« less

  17. Measuring Spatial Variability of Vapor Flux to Characterize Vadose-zone VOC Sources: Flow-cell Experiments

    PubMed Central

    Morrison, C.; Truex, M.; Oostrom, M.; Brusseau, M.L.

    2014-01-01

    A method termed vapor-phase tomography has recently been proposed to characterize the distribution of volatile organic contaminant mass in vadose-zone source areas, and to measure associated three-dimensional distributions of local contaminant mass discharge. The method is based on measuring the spatial variability of vapor flux, and thus inherent to its effectiveness is the premise that the magnitudes and temporal variability of vapor concentrations measured at different monitoring points within the interrogated area will be a function of the geospatial positions of the points relative to the source location. A series of flow-cell experiments was conducted to evaluate this premise. A well-defined source zone was created by injection and extraction of a non-reactive gas (SF6). Spatial and temporal concentration distributions obtained from the tests were compared to simulations produced with a mathematical model describing advective and diffusive transport. Tests were conducted to characterize both areal and vertical components of the application. Decreases in concentration over time were observed for monitoring points located on the opposite side of the source zone from the local–extraction point, whereas increases were observed for monitoring points located between the local–extraction point and the source zone. The results illustrate that comparison of temporal concentration profiles obtained at various monitoring points gives a general indication of the source location with respect to the extraction and monitoring points. PMID:25171394

  18. Measuring spatial variability of vapor flux to characterize vadose-zone VOC sources: flow-cell experiments.

    PubMed

    Mainhagu, J; Morrison, C; Truex, M; Oostrom, M; Brusseau, M L

    2014-10-15

    A method termed vapor-phase tomography has recently been proposed to characterize the distribution of volatile organic contaminant mass in vadose-zone source areas, and to measure associated three-dimensional distributions of local contaminant mass discharge. The method is based on measuring the spatial variability of vapor flux, and thus inherent to its effectiveness is the premise that the magnitudes and temporal variability of vapor concentrations measured at different monitoring points within the interrogated area will be a function of the geospatial positions of the points relative to the source location. A series of flow-cell experiments was conducted to evaluate this premise. A well-defined source zone was created by injection and extraction of a non-reactive gas (SF6). Spatial and temporal concentration distributions obtained from the tests were compared to simulations produced with a mathematical model describing advective and diffusive transport. Tests were conducted to characterize both areal and vertical components of the application. Decreases in concentration over time were observed for monitoring points located on the opposite side of the source zone from the local-extraction point, whereas increases were observed for monitoring points located between the local-extraction point and the source zone. The results illustrate that comparison of temporal concentration profiles obtained at various monitoring points gives a general indication of the source location with respect to the extraction and monitoring points. PMID:25171394

  19. Measuring Spatial Variability of Vapor Flux to Characterize Vadose-zone VOC Sources: Flow-cell Experiments

    SciTech Connect

    Mainhagu, Jon; Morrison, C.; Truex, Michael J.; Oostrom, Martinus; Brusseau, Mark

    2014-10-20

    A method termed vapor-phase tomography has recently been proposed to characterize the distribution of volatile organic contaminant mass in vadose-zone source areas, and to measure associated three-dimensional distributions of local contaminant mass discharge. The method is based on measuring the spatial variability of vapor flux, and thus inherent to its effectiveness is the premise that the magnitudes and temporal variability of vapor concentrations measured at different monitoring points within the interrogated area will be a function of the geospatial positions of the points relative to the source location. A series of flow-cell experiments was conducted to evaluate this premise. A well-defined source zone was created by injection and extraction of a non-reactive gas (SF6). Spatial and temporal concentration distributions obtained from the tests were compared to simulations produced with a mathematical model describing advective and diffusive transport. Tests were conducted to characterize both areal and vertical components of the application. Decreases in concentration over time were observed for monitoring points located on the opposite side of the source zone from the local–extraction point, whereas increases were observed for monitoring points located between the local–extraction point and the source zone. The results illustrate that comparison of temporal concentration profiles obtained at various monitoring points gives a general indication of the source location with respect to the extraction and monitoring points.

  20. Standardization of a micro-cytotoxicity assay for human natural killer cell lytic activity.

    PubMed

    Mariani, E; Monaco, M C; Sgobbi, S; de Zwart, J F; Mariani, A R; Facchini, A

    1994-06-24

    Cytotoxicity assays are widely used to evaluate the functional activity of NK and T cells against tumour target cells and the release of radioactive sodium chromate from labelled target cells is still the most commonly used marker of target lysis in culture supernatants. We describe here the standardization of a micro-cytotoxicity test in which the number of cytolytic effector and tumour target cells have been decreased by a factor of 10. The release obtained by 500 tumour target cells was compared with the release obtained by 5000 target cells in the standard cytotoxicity assay for target:effector cell ratios from 1:1 to 1:100. Both gamma and beta emissions of the 51Cr isotope were evaluated to determine the assay release. The results obtained by the micro-cytotoxicity assay (500 target cells) were comparable to those of the standard assay (5000 target cells) and 51Cr release evaluation using the gamma counter was the most sensitive method of determining lytic activity using 500 tumour target cells. beta counter evaluation using solid phase scintillation was found to be a reproducible alternative method, even if the lytic curves cannot be compared with those obtained using the traditional method. PMID:8034970

  1. MicroRNAs in Hyperglycemia Induced Endothelial Cell Dysfunction.

    PubMed

    Silambarasan, Maskomani; Tan, Jun Rong; Karolina, Dwi Setyowati; Armugam, Arunmozhiarasi; Kaur, Charanjit; Jeyaseelan, Kandiah

    2016-01-01

    Hyperglycemia is closely associated with prediabetes and Type 2 Diabetes Mellitus. Hyperglycemia increases the risk of vascular complications such as diabetic retinopathy, diabetic nephropathy, peripheral vascular disease and cerebro/cardiovascular diseases. Under hyperglycemic conditions, the endothelial cells become dysfunctional. In this study, we investigated the miRNA expression changes in human umbilical vein endothelial cells exposed to different glucose concentrations (5, 10, 25 and 40 mM glucose) and at various time intervals (6, 12, 24 and 48 h). miRNA microarray analyses showed that there is a correlation between hyperglycemia induced endothelial dysfunction and miRNA expression. In silico pathways analyses on the altered miRNA expression showed that the majority of the affected biological pathways appeared to be associated to endothelial cell dysfunction and apoptosis. We found the expression of ten miRNAs (miR-26a-5p, -26b-5p, 29b-3p, -29c-3p, -125b-1-3p, -130b-3p, -140-5p, -192-5p, -221-3p and -320a) to increase gradually with increasing concentration of glucose. These miRNAs were also found to be involved in endothelial dysfunction. At least seven of them, miR-29b-3p, -29c-3p, -125b-1-3p, -130b-3p, -221-3p, -320a and -192-5p, can be correlated to endothelial cell apoptosis. PMID:27070575

  2. MicroRNAs in Hyperglycemia Induced Endothelial Cell Dysfunction

    PubMed Central

    Silambarasan, Maskomani; Tan, Jun Rong; Karolina, Dwi Setyowati; Armugam, Arunmozhiarasi; Kaur, Charanjit; Jeyaseelan, Kandiah

    2016-01-01

    Hyperglycemia is closely associated with prediabetes and Type 2 Diabetes Mellitus. Hyperglycemia increases the risk of vascular complications such as diabetic retinopathy, diabetic nephropathy, peripheral vascular disease and cerebro/cardiovascular diseases. Under hyperglycemic conditions, the endothelial cells become dysfunctional. In this study, we investigated the miRNA expression changes in human umbilical vein endothelial cells exposed to different glucose concentrations (5, 10, 25 and 40 mM glucose) and at various time intervals (6, 12, 24 and 48 h). miRNA microarray analyses showed that there is a correlation between hyperglycemia induced endothelial dysfunction and miRNA expression. In silico pathways analyses on the altered miRNA expression showed that the majority of the affected biological pathways appeared to be associated to endothelial cell dysfunction and apoptosis. We found the expression of ten miRNAs (miR-26a-5p, -26b-5p, 29b-3p, -29c-3p, -125b-1-3p, -130b-3p, -140-5p, -192-5p, -221-3p and -320a) to increase gradually with increasing concentration of glucose. These miRNAs were also found to be involved in endothelial dysfunction. At least seven of them, miR-29b-3p, -29c-3p, -125b-1-3p, -130b-3p, -221-3p, -320a and -192-5p, can be correlated to endothelial cell apoptosis. PMID:27070575

  3. Heterogeneity of microRNAs expression in cervical cancer cells: over-expression of miR-196a

    PubMed Central

    Villegas-Ruiz, Vanessa; Juárez-Méndez, Sergio; Pérez-González, Oscar A; Arreola, Hugo; Paniagua-García, Lucero; Parra-Melquiadez, Miriam; Peralta-Rodríguez, Raúl; López-Romero, Ricardo; Monroy-García, Alberto; Mantilla-Morales, Alejandra; Gómez-Gutiérrez, Guillermo; Román-Bassaure, Edgar; Salcedo, Mauricio

    2014-01-01

    In recent years, the study of microRNAs associated with neoplastic processes has increased. Patterns of microRNA expression in different cell lines and different kinds of tumors have been identified; however, little is known about the alterations in regulatory pathways and genes involved in aberrant set of microRNAs. The identification of these altered microRNAs in several cervical cancer cells and potentially deregulated pathways involved constitute the principal goals of the present study. In the present work, the expression profiles of cellular microRNAs in Cervical Cancer tissues and cell lines were explored using microRNA microarray, Affymetrix. The most over-expressed was miR-196a, which was evaluated by real time PCR, and HOXC8 protein as potential target by immunohistochemistry assay. One hundred and twenty three human microRNAs differentially expressed in the cell tumor, 64 (52%) over-expressed and 59 (48%) under-expressed were observed. Among the microRNAs over-expressed, we focused on miR-196a; at present this microRNA is poorly studied in CC. The expression of this microRNA was evaluated by qRT-PCR, and HOXC8 by immunohistochemistry assay. There is not a specific microRNA expression profile in the CC cells, neither a microRNA related to HPV presence. Furthermore, the miR-196a was over-expressed, while an absence of HOXC8 expression was observed. We suggest that miR-196a could be played as oncomiR in CC. PMID:24817935

  4. Micro and nanofluidic structures for cell sorting and genomic analysis

    NASA Astrophysics Data System (ADS)

    Morton, Keith J.

    Microfluidic systems promise rapid analysis of small samples in a compact and inexpensive format. But direct scaling of lab bench protocols on-chip is challenging because laminar flows in typical microfluidic devices are characterized by non-mixing streamlines. Common microfluidic mixers and sorters work by diffusion, limiting application to objects that diffuse slowly such as cells and DNA. Recently Huang et.al. developed a passive microfluidic element to continuously separate bio-particles deterministically. In Deterministic Lateral Displacement (DLD), objects are sorted by size as they transit an asymmetric array of microfabricated posts. This thesis further develops DLD arrays with applications in three broad new areas. First the arrays are used, not simply to sort particles, but to move streams of cells through functional flows for chemical treatment---such as on-chip immunofluorescent labeling of blood cells with washing, and on-chip E.coli cell lysis with simultaneous chromosome extraction. Secondly, modular tiling of the basic DLD element is used to construct complex particle handling modes that include beam steering for jets of cells and beads. Thirdly, nanostructured DLD arrays are built using Nanoimprint Lithography (NIL) and continuous-flow separation of 100 nm and 200 nm size particles is demonstrated. Finally a number of ancillary nanofabrication techniques were developed in support of these overall goals, including methods to interface nanofluidic structures with standard microfluidic components such as inlet channels and reservoirs, precision etching of ultra-high aspect ratio (>50:1) silicon nanostructures, and fabrication of narrow (˜ 35 nm) channels used to stretch genomic length DNA.

  5. MicroRNA-140 Inhibits Cell Proliferation in Gastric Cancer Cell Line HGC-27 by Suppressing SOX4

    PubMed Central

    Zou, Jun; Xu, Youqing

    2016-01-01

    Background Gastric cancer is a malignant tumor with a high morbidity and mortality. MicroRNAs are important regulators of gene expression, influencing the progression of gastric cancer. This study aimed to reveal the role of microRNA-140 (miR-140) in gastric cancer cell proliferation and its potential mechanisms. Material/Methods Gastric cancer tissues and cell lines BGC-823, SGC-7901, and HGC-27 were used to analyze miR-140 levels compared to normal tissues and cell line GES-1. In HGC-27 cells transfected with miR-140 mimic, we performed MTT, colony formation assay, and cell cycle assay by flow cytometry. SOX4, a predicted target of miR-140, was mutated to verify its regulation by miR-140, and was overexpressed to analyze its function in cell proliferation. Doxorubicin treatment was performed to investigate the effect of miR-140 on drug resistance. Results miR-140 was down-regulated in gastric cancer tissues and cell lines, with the lowest expression level in HGC-27. miR-140 overexpression inhibited HGC-27 cell viability and colony formation and resulted in G0/G1 arrest. miR-140 suppressed SOX4 expression via binding to the 3′ untranslated region, while the mutant SOX4 could not be regulated. Overexpressing SOX4 led to promoted cell viability, colony formation, and cell cycle progress. miR-140 overexpression also improved the anti-viability effects of doxorubicin, suggesting its potential in reducing the drug resistance of gastric cells. Conclusions These findings suggest that miR-140 directly inhibits SOX4, which might be one of its mechanisms in suppressing gastric cancer cell proliferation. This study provides a promising therapeutic strategy for treating gastric cancer and facilitates microRNA research in various diseases. PMID:27353653

  6. Hysteretic Behavior upon Light Soaking in Perovskite Solar Cells Prepared via Modified Vapor-Assisted Solution Process.

    PubMed

    Liu, Chong; Fan, Jiandong; Zhang, Xing; Shen, Yanjiao; Yang, Lin; Mai, Yaohua

    2015-05-01

    Recently, the organic-inorganic hybrid perovskite solar cells exhibit rapidly rising efficiencies, while anomalous hysteresis in perovskite solar cells remains unsolvable. Herein, a high-quality perovskite thin film is prepared by a modified vapor-assisted solution process, which is a simple but well-controllable method proven to be capable of producing a thin film with full surface coverage and grain size up to micrometers. The as-fabricated perovskite solar cell has efficiency as high as 10.2%. The hysteresis effects of both planar and mesoscopic TiO2-based perovskite solar cells have been comprehensively studied upon illumination. The results demonstrate that mesoporous-based perovskite cells combined with remarkable grain size are subject to alleviating the hysteresis effects in comparison to the planar cells. Likewise, mesoscopic TiO2-based perovskite cells perform independently of illumination and bias conditions prior to the measurements, whereas the planar cells display a reversible behavior of illumination and applied bias-dependent I-V curves. The present study would refer strip road for the stability study of the perovskite solar cells. PMID:25860158

  7. Analysis of Individual Cells and Endospores by Micro-Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    Esposito, Anthony; Huser, Thomas; Talley, Chad; Hollars, Christopher; Balhorn, Rod; Lane, Stephen

    2003-03-01

    We have collected Raman spectra of individual sperm cells by confocal micro-Raman spectroscopy. The high spatial resolution of this technique allows for compositional analysis of different sections of the sperm cells. The relative intensities of protein and DNA Raman transitions allow one to define a protein-DNA ratio. We have also collected the Raman spectra of individual bacterial endospores from four species in the genus Bacillus. The spectra were generally dominated by scattering from calcium dipicolinate, although scattering assignable to protein bands was also observed. A small fraction of the spores did not exhibit Raman scattering from CaDPA, possibly due to incomplete sporulation. These examples demonstrate the applicability of micro-Raman spectroscopy as a non-invasive method for addressing variability in the composition of cells.* *This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under contract number W-7405-Eng-48.

  8. Deep Sub-micro mol{\\cdot }mol^{-1} Water-Vapor Measurement by Dual-Ball SAW Sensors for Temperature Compensation

    NASA Astrophysics Data System (ADS)

    Takeda, N.; Oizumi, T.; Tsuji, T.; Akao, S.; Takayanagi, K.; Nakaso, N.; Yamanaka, K.

    2015-12-01

    A collimated surface acoustic wave (SAW) circles around the equator of a sphere hundreds of times. Because of the long distance travel of the collimated SAW, a small change in the SAW propagation caused by the environment of the sphere can be accumulated as a measurable range in amplitude and/or in delay time. So, a spherical SAW device enables highly sensitive water-vapor measurements. In this paper, deep sub \\upmu mol{\\cdot }mol^{-1} water-vapor detection by 1 mm diameter quartz crystal ball SAW sensors is described. To measure such a low water-vapor concentration in real time, it is necessary to compensate the temperature dependence of the ball SAW sensor, which is about 20 ppm{\\cdot }°C^{-1} in delay time change. A dual-frequency burst analog detector was developed for the temperature compensation in real time. By using a harmonic SAW sensor, which was excited by 80 MHz and 240 MHz at the same time, it was confirmed that the delay time drift for a temperature range of 21.0°C ± 1.0°C became less than 0.05 ppm in delay time change. By using dual-ball SAW sensors (which included a 150 MHz sensor with a water-vapor sensitive layer and a 240 MHz sensor as a reference), water-vapor concentrations from 0.1 \\upmu mol{\\cdot }mol^{-1} to 5 \\upmu mol{\\cdot }mol^{-1} were successfully measured. It appears that the delay time change is proportional to the square root of the water-vapor concentration. The detection limit determined by the electrical noise of the system was estimated at 0.01 \\upmu mol{\\cdot }mol^{-1}.

  9. Proton exchange membrane micro fuel cells on 3D porous silicon gas diffusion layers

    NASA Astrophysics Data System (ADS)

    Kouassi, S.; Gautier, G.; Thery, J.; Desplobain, S.; Borella, M.; Ventura, L.; Laurent, J.-Y.

    2012-10-01

    Since the 90's, porous silicon has been studied and implemented in many devices, especially in MEMS technology. In this article, we present a new approach to build miniaturized proton exchange membrane micro-fuel cells using porous silicon as a hydrogen diffusion layer. In particular, we propose an innovative process to build micro fuel cells from a “corrugated iron like” 3D structured porous silicon substrates. This structure is able to increase up to 40% the cell area keeping a constant footprint on the silicon wafer. We propose here a process route to perform electrochemically 3D porous gas diffusion layers and to deposit fuel cell active layers on such substrates. The prototype peak power performance was measured to be 90 mW cm-2 in a “breathing configuration” at room temperature. These performances are less than expected if we compare with a reference 2D micro fuel cell. Actually, the active layer deposition processes are not fully optimized but this prototype demonstrates the feasibility of these 3D devices.

  10. Distinct patterns of cell motion inside a micro-channel under different osmotic conditions.

    PubMed

    Tsai, Chia-Hung Dylan; Kaneko, Makoto; Sakuma, Shinya; Arai, Fumihito

    2013-01-01

    The effect of osmotic condition on a living cell inside a micro-channel is firstly studied in this work. By utilizing a high-speed camera, we observed distinct patterns of cell motion under different osmotic conditions, which are established by saline with different concentrations of sodium chloride (NaCl). The cell motions are tracked by a computer, and are presented by the coordinates of location and time (x-t chart). The motions of cells under hypotonic condition (NaCl% < 0.9%) are convex curves on the chart while the ones under isotonic and hypertonic conditions (NaCl% ≥ 0.9%) are concave curves. Since saline is widely used in both medical practices and cell-related researches, our results point out two important facts: 1) Cells are sensitive to the percentage of NaCl. One percent difference in overall concentration makes dramatic changes in cell characteristics, such as cell stiffness. 2) The micro-channel method can clearly tell the difference between hypotonic, isotonic and hypertonic conditions according to the pattern of cell motion. Interpretations of the phenomena from different perspectives are also discussed in this paper. PMID:24110988

  11. Functional analysis of microRNAs in human hepatocellular cancer stem cells

    PubMed Central

    Meng, Fanyin; Glaser, Shannon S; Francis, Heather; DeMorrow, Sharon; Han, Yuyan; Passarini, Jenna D; Stokes, Allison; Cleary, John P; Liu, Xiuping; Venter, Julie; Kumar, Preetham; Priester, Sally; Hubble, Levi; Staloch, Dustin; Sharma, Jay; Liu, Chang-Gong; Alpini, Gianfranco

    2012-01-01

    Abstract MicroRNAs are endogenous small non-coding RNAs that regulate gene expression and cancer development. A rare population of hepatocellular cancer stem cells (HSCs) holds the extensive proliferative and self-renewal potential necessary to form a liver tumour. We postulated that specific transcriptional factors might regulate the expression of microRNAs and subsequently modulate the expression of gene products involved in phenotypic characteristics of HSCs. We evaluated the expression of microRNA in human HSCs by microarray profiling, and defined the target genes and functional effects of two groups of microRNA regulated by IL-6 and transcriptional factor Twist. A subset of highly chemoresistant and invasive HSCs was screened with aberrant expressions of cytokine IL-6 and Twist. We demonstrated that conserved let-7 and miR-181 family members were up-regulated in HSCs by global microarray-based microRNA profiling followed by validation with real-time polymerase chain reaction. Importantly, inhibition of let-7 increases the chemosensitivity of HSCs to sorafenib and doxorubicin whereas silencing of miR-181 led to a reduction in HSCs motility and invasion. Knocking down IL-6 and Twist in HSCs significantly reduced let-7 and miR-181 expression and subsequently inhibited chemoresistance and cell invasion. We showed that let-7 directly targets SOCS-1 and caspase-3, whereas miR-181 directly targets RASSF1A, TIMP3 as well as nemo-like kinase (NLK). In conclusion, alterations of IL-6- and Twist-regulated microRNA expression in HSCs play a part in tumour spreading and responsiveness to chemotherapy. Our results define a novel regulatory mechanism of let-7/miR-181s suggesting that let-7 and miR-181 may be molecular targets for eradication of hepatocellular malignancies. PMID:21352471

  12. High-efficiency CdTe thin-film solar cells using metalorganic chemical vapor deposition techniques

    NASA Astrophysics Data System (ADS)

    Nouhi, A.; Stirn, R. J.; Meyers, P. V.; Liu, C. H.

    1989-06-01

    Energy conversion efficiency of metalorganic chemical vapor deposited CdTe as an intrinsic active layer in n-i-p solar cell structures is reported. Small-area devices with efficiencies over 9 percent have been demonstrated. I-V characteristics, photospectral response, and the results of Auger profiling of structural composition for typical devices will be presented. Also presented are preliminary results on similar photovoltaic devices having Cd(0.85)Mn(0.15)Te in place of CdTe as an i layer.

  13. High-efficiency CdTe thin-film solar cells using metalorganic chemical vapor deposition techniques

    NASA Technical Reports Server (NTRS)

    Nouhi, A.; Stirn, R. J.; Meyers, P. V.; Liu, C. H.

    1989-01-01

    Energy conversion efficiency of metalorganic chemical vapor deposited CdTe as an intrinsic active layer in n-i-p solar cell structures is reported. Small-area devices with efficiencies over 9 percent have been demonstrated. I-V characteristics, photospectral response, and the results of Auger profiling of structural composition for typical devices will be presented. Also presented are preliminary results on similar photovoltaic devices having Cd(0.85)Mn(0.15)Te in place of CdTe as an i layer.

  14. A flexible micro biofuel cell utilizing hydrogel containing ascorbic acid

    NASA Astrophysics Data System (ADS)

    Goto, Hideaki; Fukushi, Yudai; Nishioka, Yasushiro

    2014-11-01

    This paper reports on a biofuel cell with a dimension of 13×24 mm2 fabricated on a flexible polyimide substrate. I its porous carbon-coated platinum (Pt) electrodes of 3 mm in width and 10 mm in length were fabricated using photolithography and screen printing techniques. Porous carbon was deposited by screen printing of carbon black ink on the Pt electrode surfaces in order to increase the effective electrode surface area and to absorb more enzymes on the electrode surfaces. It utilizes a solidified ascorbic acid (AA) aqueous solution in an agarose hydrogel to increase the portability. The maximum power and power density for the biofuel cell with the fuel unit containing 100 mM AA were 0.063 μW and 0.21 μW/cm2 at 0.019 V, respectively.

  15. Micro-tubular solid oxide fuel cell based on a porous yttria-stabilized zirconia support

    PubMed Central

    Panthi, Dhruba; Tsutsumi, Atsushi

    2014-01-01

    Solid oxide fuel cells (SOFCs) are promising electrochemical energy conversion devices owing to their high power generation efficiency and environmentally benign operation. Micro-tubular SOFCs, which have diameters ranging from a few millimeters to the sub-millimeter scale, offer several advantages over competing SOFCs such as high volumetric power density, good endurance against thermal cycling, and flexible sealing between fuel and oxidant streams. Herein, we successfully realized a novel micro-tubular SOFC design based on a porous yttria-stabilized zirconia (YSZ) support using multi-step dip coating and co-sintering methods. The micro-tubular SOFC consisted of Ni-YSZ, YSZ, and strontium-doped lanthanum manganite (LSM)–YSZ as the anode, electrolyte, and cathode, respectively. In addition, to facilitate current collection from the anode and cathode, Ni and LSM were applied as an anode current collector and cathode current collector, respectively. Micro-crystalline cellulose was selected as a pore former to achieve better shrinkage behavior of the YSZ support so that the electrolyte layer could be densified at a co-sintering temperature of 1300°C. The developed micro-tubular design showed a promising electrochemical performance with maximum power densities of 525, 442, and 354 mW cm−2 at 850, 800, and 750°C, respectively. PMID:25169166

  16. Micro-tubular solid oxide fuel cell based on a porous yttria-stabilized zirconia support

    NASA Astrophysics Data System (ADS)

    Panthi, Dhruba; Tsutsumi, Atsushi

    2014-08-01

    Solid oxide fuel cells (SOFCs) are promising electrochemical energy conversion devices owing to their high power generation efficiency and environmentally benign operation. Micro-tubular SOFCs, which have diameters ranging from a few millimeters to the sub-millimeter scale, offer several advantages over competing SOFCs such as high volumetric power density, good endurance against thermal cycling, and flexible sealing between fuel and oxidant streams. Herein, we successfully realized a novel micro-tubular SOFC design based on a porous yttria-stabilized zirconia (YSZ) support using multi-step dip coating and co-sintering methods. The micro-tubular SOFC consisted of Ni-YSZ, YSZ, and strontium-doped lanthanum manganite (LSM)-YSZ as the anode, electrolyte, and cathode, respectively. In addition, to facilitate current collection from the anode and cathode, Ni and LSM were applied as an anode current collector and cathode current collector, respectively. Micro-crystalline cellulose was selected as a pore former to achieve better shrinkage behavior of the YSZ support so that the electrolyte layer could be densified at a co-sintering temperature of 1300°C. The developed micro-tubular design showed a promising electrochemical performance with maximum power densities of 525, 442, and 354 mW cm-2 at 850, 800, and 750°C, respectively.

  17. Performance of vapor-fed direct dimethyl ether fuel cell utilizing high temperature polybenzimidazole polymer electrolyte membrane

    NASA Astrophysics Data System (ADS)

    Neutzler, Jay; Qian, Guoqing; Huang, Kevin; Benicewicz, Brian

    2012-10-01

    There is increasing interest in dimethyl ether (DME) as a synthetic fuel. It has present-day relevance and introduces an effective path forward as an energy-dense, low-pressure hydrogen carrier/storage fuel for fuel cells with applications in transportation, stationary, and portable power. Direct reaction DME fuel cells have particular relevance to portable power. This study presents the performance of the vapor-fed direct reaction of DME using high temperature Polybenzimidazole (PBI) Polymer Electrolyte Membrane (PEM). Catalyzed PBI membrane utilized a Pt/Ru black anode and a Pt/C supported cathode. Performance was evaluated from temperatures of 180 °C-210 °C and at pressures from 100 kPa to 300 kPa. A strong performance correlation was observed in this study for these temperatures and pressures. A peak power density of 50 mW cm-2 was achieved at 180 °C without back pressure, whereas, an increase to 129 mW cm-2 was achieved at 210 °C at 300 kPa pressure. The performance of high temperature PBI PEMFCs with direct vapor-fed DME are investigated with emphasis on the critical variables of cell operation; temperature, back pressure, and humidity.

  18. MicroRNA and Protein Profiling of Brain Metastasis Competent Cell-Derived Exosomes

    PubMed Central

    Camacho, Laura; Guerrero, Paola; Marchetti, Dario

    2013-01-01

    Exosomes are small membrane vesicles released by most cell types including tumor cells. The intercellular exchange of proteins and genetic material via exosomes is a potentially effective approach for cell-to-cell communication and it may perform multiple functions aiding to tumor survival and metastasis. We investigated microRNA and protein profiles of brain metastatic (BM) versus non-brain metastatic (non-BM) cell-derived exosomes. We studied the cargo of exosomes isolated from brain-tropic 70W, MDA-MB-231BR, and circulating tumor cell brain metastasis-selected markers (CTC1BMSM) variants, and compared them with parental non-BM MeWo, MDA-MB-231P and CTC1P cells, respectively. By performing microRNA PCR array we identified one up-regulated (miR-210) and two down-regulated miRNAs (miR-19a and miR-29c) in BM versus non-BM exosomes. Second, we analyzed the proteomic content of cells and exosomes isolated from these six cell lines, and detected high expression of proteins implicated in cell communication, cell cycle, and in key cancer invasion and metastasis pathways. Third, we show that BM cell-derived exosomes can be internalized by non-BM cells and that they effectively transport their cargo into cells, resulting in increased cell adhesive and invasive potencies. These results provide a strong rationale for additional investigations of exosomal proteins and miRNAs towards more profound understandings of exosome roles in brain metastasis biogenesis, and for the discovery and application of non-invasive biomarkers for new therapies combating brain metastasis. PMID:24066071

  19. Panchromatic polymer-polymer ternary solar cells enhanced by Forster resonance energy transfer and solvent vapor annealing

    DOE PAGESBeta

    Goh, Tenghooi; Sfeir, Matthew Y.; Huang, Jing -Shun; Bartolome, Benjamin; Vaisman, Michelle; Lee, Minjoo L.; Taylor, Andre D.

    2015-08-04

    Thanks to the bulk-heterojunction (BHJ) feature of polymer solar cells (PSC), additional light active components can be added with ease to form ternary solar cells. This strategy has achieved great success largely due to expanded spectral response range and improved power conversion efficiency (PCE) without incurring excessive processing costs. Here, we report ternary blend polymer–polymer solar cells comprised of PTB7, P3HT, and PC71BM with PCE as high as 8.2%. Analyses of femtosecond time resolved photoluminescence and transient absorption spectroscopy data confirm that P3HT is effective in transferring energy non-radiatively by inducing excitons and prolonging their overall lifetime in PTB7. Asmore » a result, solvent vapor annealing (SVA) treatment was employed to rectify the overly-coarse morphology, thus enhancing the fill factor, reducing interfacial recombination, and boosting the PCE to 8.7%.« less

  20. Panchromatic polymer-polymer ternary solar cells enhanced by Forster resonance energy transfer and solvent vapor annealing

    SciTech Connect

    Goh, Tenghooi; Sfeir, Matthew Y.; Huang, Jing -Shun; Bartolome, Benjamin; Vaisman, Michelle; Lee, Minjoo L.; Taylor, Andre D.

    2015-08-04

    Thanks to the bulk-heterojunction (BHJ) feature of polymer solar cells (PSC), additional light active components can be added with ease to form ternary solar cells. This strategy has achieved great success largely due to expanded spectral response range and improved power conversion efficiency (PCE) without incurring excessive processing costs. Here, we report ternary blend polymer–polymer solar cells comprised of PTB7, P3HT, and PC71BM with PCE as high as 8.2%. Analyses of femtosecond time resolved photoluminescence and transient absorption spectroscopy data confirm that P3HT is effective in transferring energy non-radiatively by inducing excitons and prolonging their overall lifetime in PTB7. As a result, solvent vapor annealing (SVA) treatment was employed to rectify the overly-coarse morphology, thus enhancing the fill factor, reducing interfacial recombination, and boosting the PCE to 8.7%.

  1. Overview of Micro- and Nano-Technology Tools for Stem Cell Applications: Micropatterned and Microelectronic Devices

    PubMed Central

    Cagnin, Stefano; Cimetta, Elisa; Guiducci, Carlotta; Martini, Paolo; Lanfranchi, Gerolamo

    2012-01-01

    In the past few decades the scientific community has been recognizing the paramount role of the cell microenvironment in determining cell behavior. In parallel, the study of human stem cells for their potential therapeutic applications has been progressing constantly. The use of advanced technologies, enabling one to mimic the in vivo stem cell microenviroment and to study stem cell physiology and physio-pathology, in settings that better predict human cell biology, is becoming the object of much research effort. In this review we will detail the most relevant and recent advances in the field of biosensors and micro- and nano-technologies in general, highlighting advantages and disadvantages. Particular attention will be devoted to those applications employing stem cells as a sensing element. PMID:23202240

  2. Knockdown of microRNA-127 reverses adriamycin resistance via cell cycle arrest and apoptosis sensitization in adriamycin-resistant human glioma cells

    PubMed Central

    Feng, Ren; Dong, Lei

    2015-01-01

    The aim of this study was to investigate signaling pathways for reversal of microRNA-127-mediated multi-drug resistance (MDR) in gliomas cells. Adriamycin-resistant glioma cell lines U251/adr and U87-MG/adr were established and we found that anti-microRNA-127 markedly reduced microRNA-127 expression levels in a time-dependent manner, leading to distinct inhibition of cell proliferation and increased apoptosis and the content of intracellular Rh123. Silencing of microRNA-127 significantly increased the sensitivity of U251/ADR and U87-MG/adr cells to adriamycin, compared to cells transfected with negative control siRNA. Silencing of microRNA-127 also significantly reduced the mRNA and protein expression levels of MDR1 and MRP1, which are major ATP-binding cassette (ABC) transporter linked to multi-drug resistance in cancer cells. And Runx2, p53, bcl-2 and survivin, which are important role in cell apoptosis, also markedly changed after microRNA-127 silencing. In addition, down-regulating microRNA-127 decreased the level of phosphorylated-Akt. Our data indicate that down-regulation of micorRNA-127 can trigger apoptosis and overcome drug resistance of gliomas cells. Therefore, this resistance of adriamycin in gliomas can be cancelled by silencing expression of microRNA-127. PMID:26261488

  3. Knockdown of microRNA-127 reverses adriamycin resistance via cell cycle arrest and apoptosis sensitization in adriamycin-resistant human glioma cells.

    PubMed

    Feng, Ren; Dong, Lei

    2015-01-01

    The aim of this study was to investigate signaling pathways for reversal of microRNA-127-mediated multi-drug resistance (MDR) in gliomas cells. Adriamycin-resistant glioma cell lines U251/adr and U87-MG/adr were established and we found that anti-microRNA-127 markedly reduced microRNA-127 expression levels in a time-dependent manner, leading to distinct inhibition of cell proliferation and increased apoptosis and the content of intracellular Rh123. Silencing of microRNA-127 significantly increased the sensitivity of U251/ADR and U87-MG/adr cells to adriamycin, compared to cells transfected with negative control siRNA. Silencing of microRNA-127 also significantly reduced the mRNA and protein expression levels of MDR1 and MRP1, which are major ATP-binding cassette (ABC) transporter linked to multi-drug resistance in cancer cells. And Runx2, p53, bcl-2 and survivin, which are important role in cell apoptosis, also markedly changed after microRNA-127 silencing. In addition, down-regulating microRNA-127 decreased the level of phosphorylated-Akt. Our data indicate that down-regulation of micorRNA-127 can trigger apoptosis and overcome drug resistance of gliomas cells. Therefore, this resistance of adriamycin in gliomas can be cancelled by silencing expression of microRNA-127. PMID:26261488

  4. Large-Scale Identification of MicroRNA Targets in Murine Dgcr8-Deficient Embryonic Stem Cell Lines

    PubMed Central

    Davis, Matthew P. A.; Abreu-Goodger, Cei; van Dongen, Stijn; Lu, Dong; Tate, Peri H.; Bartonicek, Nenad; Kutter, Claudia; Liu, Pentao; Skarnes, William C.; Enright, Anton J.; Dunham, Ian

    2012-01-01

    Small RNAs such as microRNAs play important roles in embryonic stem cell maintenance and differentiation. A broad range of microRNAs is expressed in embryonic stem cells while only a fraction of their targets have been identified. We have performed large-scale identification of embryonic stem cell microRNA targets using a murine embryonic stem cell line deficient in the expression of Dgcr8. These cells are heavily depleted for microRNAs, allowing us to reintroduce specific microRNA duplexes and identify refined target sets. We used deep sequencing of small RNAs, mRNA expression profiling and bioinformatics analysis of microRNA seed matches in 3′ UTRs to identify target transcripts. Consequently, we have identified a network of microRNAs that converge on the regulation of several important cellular pathways. Additionally, our experiments have revealed a novel candidate for Dgcr8-independent microRNA genesis and highlighted the challenges currently facing miRNA annotation. PMID:22912678

  5. Electromagnetic field interactions with micro channels, particles and cells: Application to advanced cytometry

    NASA Astrophysics Data System (ADS)

    Venkatapathi, Murugesan

    This thesis involves a study of the interaction of laser beams with micro channels and micro particles/cells using the electromagnetic field approach. This problem is relevant to the next generation cytometry, in particular to model based design of flow cytometers. The field approach is applied to study light scatter from particles/cells and also internal and scattered fields of cylindrical micro channels that are important for optical interrogation of particles and cells flowing through. Though current flow cytometers use qualitative fluorescence measurements for biological analysis, other viable optical interrogation techniques like light scatter, quantitative fluorescence and Coherent anti-stokes Raman scatter (CARS) are being studied for application to flow cytometry. The light scatter from particles and cells in a flow cytometer has been studied with the objective of extracting useful information about the particles using scatter measurements. First, the correlation between the size of particles and the current forward scatter measurements was both analytically modeled and experimentally determined. These results indicated that integrated scatter measurements currently used in flow cytometry (forward and side scatter) cannot be used to unambiguously estimate size, shape or refractive index of particles for classification. It is shown that multi-angle scatter measurements can be used to classify micro spheres of different sizes/refractive indices and different bacteria species, provided the scatter measurements are designed based on numerical scatter models. The numerical scatter models were then also used to do a preliminary study of correlation of scatter with internal structure of simple cells like stem cells. A few multivariate statistical methods have been applied for the classification of such particles in flow cytometry using scatter and multi-spectral fluorescence measurements. Typically the micro channels used in flow cytometry have square or circular

  6. MicroRNA-194 Regulates Hepatocytic Differentiation of Progenitor Cells by Targeting YAP1

    PubMed Central

    Jung, Kwang Hwa; McCarthy, Ryan L.; Zhou, Chong; Uprety, Nadima; Barton, Michelle Craig; Beretta, Laura

    2015-01-01

    MicroRNA expression profiling in human liver progenitor cells following hepatocytic differentiation identified miR-122 and miR-194 as the microRNAs most strongly upregulated during hepatocytic differentiation of progenitor cells. MiR-194 was also highly upregulated following hepatocytic differentiation of human embryonic stem cells (hESCs). Overexpression of miR-194 in progenitor cells accelerated their differentiation into hepatocytes, as measured by morphological features such as canaliculi and expression of hepatocytic markers. Overexpression of miR-194 in hESCs induced their spontaneous differentiation, a phenotype accompanied with accelerated loss of the pluripotent factors OCT4 and NANOG and decrease in mesoderm marker HAND1 expression. We then identified YAP1 as a direct target of miR-194. Inhibition of YAP1 strongly induced hepatocytic differentiation of progenitor cells and YAP1 over expression reversed the miR-194-induced hepatocytic differentiation of progenitor cells. In conclusion, we identified miR-194 as a potent inducer of hepatocytic differentiation of progenitor cells and further identified YAP1 as a mediator of miR-194's effects on hepatocytic differentiation and liver progenitor cell fate. PMID:26731713

  7. Micro-Raman spectroscopy Detects Individual Neoplastic and Normal Hematopoietic Cells

    SciTech Connect

    Chan, J W; Taylor, D; Zwerdling, T; Lane, S M; Ihara, K; Huser, T

    2005-01-18

    Current methods for identifying neoplastic cells and discerning them from their normal counterparts are often non-specific, slow, biologically perturbing, or a combination, thereof. Here, we show that single-cell micro-Raman spectroscopy averts these shortcomings and can be used to discriminate between unfixed normal human lymphocytes and transformed Jurkat and Raji lymphocyte cell lines based on their biomolecular Raman signatures. We demonstrate that single-cell Raman spectra provide a highly reproducible biomolecular fingerprint of each cell type. Characteristic peaks, mostly due to different DNA and protein concentrations, allow for discerning normal lymphocytes from transformed lymphocytes with high confidence (p << 0.05). Spectra are also compared and analyzed by principal component analysis (PCA) to demonstrate that normal and transformed cells form distinct clusters that can be defined using just two principal components. The method is shown to have a sensitivity of 98.3% for cancer detection, with 97.2% of the cells being correctly classified as belonging to the normal or transformed type. These results demonstrate the potential application of confocal micro-Raman spectroscopy as a clinical tool for single cell cancer detection based on intrinsic biomolecular signatures, therefore eliminating the need for exogenous fluorescent labeling.

  8. Cell-Based Biosensor to Report DNA Damage in Micro- and Nanosystems

    PubMed Central

    2015-01-01

    Understanding how newly engineered micro- and nanoscale materials and systems that interact with cells impact cell physiology is crucial for the development and ultimate adoption of such technologies. Reports regarding the genotoxic impact of forces applied to cells in such systems that can both directly or indirectly damage DNA emphasize the need for developing facile methods to assess how materials and technologies affect cell physiology. To address this need we have developed a TurboRFP-based DNA damage reporter cell line in NIH-3T3 cells that fluoresce to report genotoxic stress caused by a wide variety of agents, from chemical genotoxic agents to UV-C radiation. Our biosensor was successfully implemented in reporting the genotoxic impact of nanomaterials, demonstrating the ability to assess size dependent geno- and cyto-toxicity. The biosensor cells can be assayed in a high throughput, noninvasive manner, with no need for overly sophisticated equipment or additional reagents. We believe that this open-source biosensor is an important resource for the community of micro- and nanomaterials and systems designers and users who wish to evaluate the impact of systems and materials on cell physiology. PMID:25001406

  9. Optics development for micro-cell based CPV modules

    NASA Astrophysics Data System (ADS)

    Menard, Etienne; Sullivan, Michael; Wilson, John; Fisher, Brent; Seel, Steve; Meitl, Matthew; Ghosal, Kanchan; Burroughs, Scott

    2011-10-01

    Semprius' two-stage pupil imaging concentrated photovoltaic (CPV) module design incorporates extremely costeffective glass ball secondary lenses in addition to plano-convex primary lens arrays. Optimization of the optical concentrator design involves modeling the illumination uniformity of the primary aperture (the 'pupil') on the multijunction solar cell in response to the secondary lens index, diameter, surface quality, location, and tolerance offsets. We reconcile our theoretical model with experimental results from a single fully adjustable 'concentrating unit cell', and we thereby create a robust model for design updates, for tolerance and sensitivity modeling, and for prediction of full module and on-sun tracker performance based on receiver placement relative to our primary lens array. In this paper, we discuss the rationale behind our optics approach, our criteria for optimizing our optics, and our tolerancing approach. Then we discuss our experimental approach, including our universally adjustable 'concentrating unit' fixture, our light source, and our primary and secondary optics. We show sensitivity curves of our 'concentrating unit' performance to receiver placement, and ball lens size. We reconcile these with our ray-traced model, and, finally, we show predicted module performance based on receiver tolerance data and receiver wiring in the module using a parameter driven high level circuit model.

  10. Role of microRNA in prostate cancer stem/progenitor cells regulation.

    PubMed

    Tao, Z-Q; Shi, A-M; Li, R; Wang, Y-Q; Wang, X; Zhao, J

    2016-07-01

    Most of the human tumors contain a population of cells with stem cell properties, called cancer stem cells (CSCs), which are believed to be responsible for tumor establishment, metastasis, and resistance to clinical therapy. It's crucial to understand the regulatory mechanisms unique to CSCs, in order to design CSC-specific therapeutics. Recent discoveries of microRNA (miRNA) have provided a new avenue for understanding the regulatory mechanisms of cancer. The present review article will discuss important milestones associated with mircroRNA regulation during prostate carcinogenesis. PMID:27460733

  11. Polymeric optical fiber tweezers as a tool for single cell micro manipulation and sensing

    NASA Astrophysics Data System (ADS)

    Rodrigues Ribeiro, R. S.; Soppera, O.; Guerreiro, A.; Jorge, P. A...

    2015-09-01

    In this paper a new type of polymeric fiber optic tweezers for single cell manipulation is reported. The optical trapping of a yeast cell using a polymeric micro lens fabricated by guided photo polymerization at the fiber tip is demonstrated. The 2D trapping of the yeast cells is analyzed and maximum optical forces on the pN range are calculated. The experimental results are supported by computational simulations using a FDTD method. Moreover, new insights on the potential for simultaneous sensing and optical trapping, are presented.

  12. MicroRNA-92b represses invasion-metastasis cascade of esophageal squamous cell carcinoma

    PubMed Central

    Ma, Gang; Jing, Chao; Li, Lin; Huang, Furong; Ding, Fang; Wang, Baona; Lin, Dongmei; Luo, Aiping; Liu, Zhihua

    2016-01-01

    Invasion and metastasis are major contributors to cancer-caused death in patients suffered from esophageal squamous cell carcinoma (ESCC). To explore the microRNAs involved in regulating invasion-metastasis cascade of ESCC, we established two pairs of sublines (30-U/D and 180-U/D) with distinct motility capacity from two ESCC cell lines (KYSE30 and KYSE180). Screening of the differentially expressed microRNAs identified that microRNA-92b-3p (miR-92b) could dramatically inhibit invasion and metastasis of ESCC cells in vitro and in vivo. Subsequent studies showed that miR-92b exerted its inhibitory function through suppressing the expression of integrin αV (ITGAV), which further reduced phosphrylated FAK and impaired Rac1 activation. Moreover, higher expression of miR-92b in ESCC tissues correlated inversely with lymph node metastasis and indicated better prognosis. Together, these results for the first time describe how miR-92b suppresses the motility of ESCC cells and provide a promise for diagnosis or therapy of ESCC invasion and metastasis. PMID:26934001

  13. The microRNA-dependent cell fate of multipotent stromal cells differentiating to endothelial cells.

    PubMed

    Cha, Min-Ji; Choi, Eunhyun; Lee, Seahyoung; Song, Byeong-Wook; Yoon, Cheesoon; Hwang, Ki-Chul

    2016-02-15

    In the endothelial recovery process, bone marrow-derived MSCs are a potential source of cells for both research and therapy, and their capacities to self-renew and to differentiate into all the cell types in the human body make them a promising therapeutic agent for remodeling cellular differentiation and a valuable resource for the treatment of many diseases. Based on the results provided in a miRNA database, we selected miRNAs with unique targets in cell fate-related signaling pathways. The tested miRNAs targeting GSK-3β (miR-26a), platelet-derived growth factor receptor, and CD133 (miR-26a and miR-29b) induced MSC differentiation into functional ECs, whereas miRNAs targeting VEGF receptor (miR-15, miR-144, miR-145, and miR-329) inhibited MSC differentiation into ECs through VEGF stimulation. In addition, the expression levels of these miRNAs were correlated with in vivo physiological endothelial recovery processes. These findings indicate that the miRNA expression profile is distinct for cells in different stages of differentiation from MSCs to ECs and that specific miRNAs can function as regulators of endothelialization. PMID:26854694

  14. Integrated Field Testing of Fuel Cells and Micro-Turbines

    SciTech Connect

    Jerome R. Temchin; Stephen J. Steffel

    2005-11-01

    A technical and economic evaluation of the prospects for the deployment of distributed generation on Long Beach Island, New Jersey concluded that properly sited DG would defer upgrading of the electric power grid for 10 years. This included the deployment of fuel cells or microturbines as well as reciprocating engines. The implementation phase of this project focused on the installation of a 120 kW CHP microturbine system at the Harvey Cedars Bible Conference in Harvey Cedars, NJ. A 1.1 MW generator powered by a gas-fired reciprocating engine for additional grid support was also installed at a local substation. This report contains installation and operation issues as well as the utility perspective on DG deployment.

  15. Micro-PIV (micro particle image velocimetry) visualization of red blood cells (RBCs) sucked by a female mosquito

    NASA Astrophysics Data System (ADS)

    Kikuchi, K.; Mochizuki, O.

    2011-06-01

    A mosquito's pump is a highly effective system in the small suction domain. To understand a mosquito's blood suction mechanism, we analysed the characteristics of red blood cells (RBCs) in human blood during and after suction by a female mosquito. Focussing on the flow patterns of the RBCs in human blood being sucked by a mosquito, we visualized blood flow by using a micro-particle image velocimetry (μ-PIV) system, which combines an optical microscope and a PIV method. In an ex vivo experiment, a female mosquito was supplied diluted blood at the tip of the proboscis. We examined the blood flow around the tip of the proboscis and observed that RBCs were periodically sucked towards a hole around the tip. The sucked RBCs then homogeneously flowed parallel to the inner surface of the proboscis without adhering to the wall. Furthermore, using a bioelectric recording system, we directly measured electrical signals generated during suction by the pump muscles located in the mosquito's head. We found that the electrical signal power was synchronized with the acceleration of the RBCs in the sucking phase. A histological stain method was adapted for the observation of the form and internal structure of RBCs in the mosquito. Although the blood flow analysis revealed that the RBCs underwent shear stress during suction, RBCs in the mosquito's stomach maintained their original shape.

  16. Tuning the cell fate of neurons and glia by microRNAs

    PubMed Central

    Bian, Shan; Xu, Tian-le; Sun, Tao

    2013-01-01

    The proper function of the nervous system depends on precise production and connection of distinct neurons and glia. Cell fate determination of neurons and glia is tightly controlled by complex gene expression regulation in the developing and adult nervous system. Emerging evidence has demonstrated the importance of noncoding microRNAs (miRNAs) in neural development and function. This review highlights current discoveries of miRNA functions in specifying neuronal and glial cell fate. We summarize the roles of miRNAs in expansion and differentiation of neural stem cells, specification of neuronal subtypes and glial cells, reprogramming of functional neurons from embryonic stem cells and fibroblasts, and left-right asymmetric organization of neuronal subtypes. Investigating the network of interactions between miRNAs and target genes will reveal new gene regulation machinery involved in tuning the cell fate decisions of neurons and glia. PMID:23978589

  17. Manipulating biological agents and cells in micro-scale volumes for applications in medicine

    PubMed Central

    Tasoglu, Savas; Gurkan, Umut Atakan; Wang, ShuQi

    2013-01-01

    Recent technological advances provide new tools to manipulate cells and biological agents in micro/nano-liter volumes. With precise control over small volumes, the cell microenvironment and other biological agents can be bioengineered; interactions between cells and external stimuli can be monitored; and the fundamental mechanisms such as cancer metastasis and stem cell differentiation can be elucidated. Technological advances based on the principles of electrical, magnetic, chemical, optical, acoustic, and mechanical forces lead to novel applications in point-of-care diagnostics, regenerative medicine, in vitro drug testing, cryopreservation, and cell isolation/purification. In this review, we first focus on the underlying mechanisms of emerging examples for cell manipulation in small volumes targeting applications such as tissue engineering. Then, we illustrate how these mechanisms impact the aforementioned biomedical applications, discuss the associated challenges, and provide perspectives for further development. PMID:23575660

  18. Multiscale Modeling of Cell Interaction in Angiogenesis: From the Micro- to Macro-scale

    NASA Astrophysics Data System (ADS)

    Pillay, Samara; Maini, Philip; Byrne, Helen

    Solid tumors require a supply of nutrients to grow in size. To this end, tumors induce the growth of new blood vessels from existing vasculature through the process of angiogenesis. In this work, we use a discrete agent-based approach to model the behavior of individual endothelial cells during angiogenesis. We incorporate crowding effects through volume exclusion, motility of cells through biased random walks, and include birth and death processes. We use the transition probabilities associated with the discrete models to determine collective cell behavior, in terms of partial differential equations, using a Markov chain and master equation framework. We find that the cell-level dynamics gives rise to a migrating cell front in the form of a traveling wave on the macro-scale. The behavior of this front depends on the cell interactions that are included and the extent to which volume exclusion is taken into account in the discrete micro-scale model. We also find that well-established continuum models of angiogenesis cannot distinguish between certain types of cell behavior on the micro-scale. This may impact drug development strategies based on these models.

  19. The functional micro-organization of grid cells revealed by cellular-resolution imaging

    PubMed Central

    Heys, James G.; Rangarajan, Krsna V.; Dombeck, Daniel A.

    2015-01-01

    Summary Establishing how grid cells are anatomically arranged, on a microscopic scale, in relation to their firing patterns in the environment would facilitate a greater micro-circuit level understanding of the brain’s representation of space. However, all previous grid cell recordings used electrode techniques that provide limited descriptions of fine-scale organization. We therefore developed a technique for cellular-resolution functional imaging of medial entorhinal cortex (MEC) neurons in mice navigating a virtual linear track, enabling a new experimental approach to study MEC. Using these methods, we show that grid cells are physically clustered in MEC compared to non-grid cells. Additionally, we demonstrate that grid cells are functionally micro-organized: The similarity between the environment firing locations of grid cell pairs varies as a function of the distance between them according to a “Mexican Hat” shaped profile. This suggests that, on average, nearby grid cells have more similar spatial firing phases than those further apart. PMID:25467986

  20. MicroRNA-155 confers encephalogenic potential to Th17 cells by promoting effector gene expression.

    PubMed

    Hu, Ruozhen; Huffaker, Thomas B; Kagele, Dominique A; Runtsch, Marah C; Bake, Erin; Chaudhuri, Aadel A; Round, June L; O'Connell, Ryan M

    2013-06-15

    Th17 cells are central to the pathogenesis of autoimmune disease, and recently specific noncoding microRNAs have been shown to regulate their development. However, it remains unclear whether microRNAs are also involved in modulating Th17 cell effector functions. Consequently, we examined the role of miR-155 in differentiated Th17 cells during their induction of experimental autoimmune encephalomyelitis. Using adoptive transfer experiments, we found that highly purified, myelin oligodendrocyte glycoprotein Ag-specific Th17 cells lacking miR-155 were defective in their capacity to cause experimental autoimmune encephalomyelitis. Gene expression profiling of purified miR-155(-/-)IL-17F(+) Th17 cells identified a subset of effector genes that are dependent on miR-155 for their proper expression through a mechanism involving repression of the transcription factor Ets1. Among the genes reduced in the absence of miR-155 was IL-23R, resulting in miR-155(-/-) Th17 cells being hyporesponsive to IL-23. Taken together, our study demonstrates a critical role for miR-155 in Th17 cells as they unleash autoimmune inflammation and finds that this occurs through a signaling network involving miR-155, Ets1, and the clinically relevant IL-23-IL-23R pathway. PMID:23686497

  1. Investigation of Micro- and Macro-Scale Transport Processes for Improved Fuel Cell Performance

    SciTech Connect

    Gu, Wenbin

    2015-02-05

    This report documents the work performed by General Motors (GM) under the Cooperative agreement No. DE-EE0000470, “Investigation of Micro- and Macro-Scale Transport Processes for Improved Fuel Cell Performance,” in collaboration with the Penn State University (PSU), University of Tennessee Knoxville (UTK), Rochester Institute of Technology (RIT), and University of Rochester (UR) via subcontracts. The overall objectives of the project are to investigate and synthesize fundamental understanding of transport phenomena at both the macro- and micro-scales for the development of a down-the-channel model that accounts for all transport domains in a broad operating space. GM as a prime contractor focused on cell level experiments and modeling, and the Universities as subcontractors worked toward fundamental understanding of each component and associated interface.

  2. Micro Corona Ionizer as an Ozone Source for Bacterial Cell Lysis

    NASA Astrophysics Data System (ADS)

    Lee, Eun-Hee; Lim, Hyun Jeong; Chua, Beelee; Son, Ahjeong

    2015-04-01

    DNA extraction is a critical process of DNA assays including polymerase chain reaction (PCR), microarrays, molecular cloning, and DNA hybridization which has been well established and can be implemented by commercial kits. DNA extraction involves cell lysis, precipitation, and purification through the combination of physical and chemical processes. Cell lysis is essential to high DNA recovery yield which can be achieved via a variety of physical, chemical, and enzymatic methods. However, these methods were originally developed for bioassays that were labor intensive, time consuming, and vulnerable to contamination and inhibition. Here, we proposed to employ a micro corona ionizer as an ozone source to lyse bacterial cells. Ozone has been well known and used as a disinfectant which allows cell lysis and DNA extraction. Previously, we have shown that a micro corona ionizer is capable of generating a significant amount of ozone. In this study, we employed the micro corona ionizer for the bacterial cell lysis which consists of a 50 μm diameter cantilever wire as the discharge cathode and a 50 μm thick copper foil as anode. Applied voltages varied from 1900 to 2200 V with corresponding corona currents from 16 to 28 μA. The resultant ozone (concentration > 0.14 ppm) generated from the micro corona ionizer was bubbled into the sample via a miniature pump. We demonstrated the cell lysis of Pseudomonas putida as the target bacterium using the micro corona ionizer. At a flow rate of 38 ml/min and applied corona voltage of 2000 V, 98.5 ± 0.2% lysis (normalized to sonication result) was achieved after 10 min. In comparison, untreated and air-treated samples showed normalized % lysis of 11.9 ± 2.4 and 36.1 ± 1.7%, respectively. We also showed that the cell lysis efficiency could be significantly increased by increasing the flow rate and the applied corona voltage. By comparing the experimental results for continuous and pulsed treatment, we verified that the percentage of

  3. Characterization of biofumigated Ralstonia solanacearum cells using micro-Raman spectroscopy and electron microscopy.

    PubMed

    Paret, Mathews L; Sharma, Shiv K; Alvarez, Anne M

    2012-01-01

    Essential oils of palmarosa, lemongrass, and eucalyptus have shown promise as biofumigants for control of the bacterial wilt disease of edible ginger (Zingiber officinale) caused by Ralstonia solanacearum race 4 in previous potting medium studies. Biochemical changes in R. solanacearum cells were evaluated with micro-Raman spectroscopy following treatment with essential oils at different concentrations (0.04, 0.07, and 0.14% [vol/vol] of culture medium) and changes in cell structure were observed using electron microscopy. All treatments except palmarosa oil at 0.04% caused significant reductions in levels of amino acids, purine and pyrimidine bases of nucleic acids, carbohydrates, and lipids, as indicated by significant reduction in Raman peak heights at 621, 1,003, and 1,031 inverse centimeters (cm(-1)) (phenylalanine); 643, 827, 852, 1,158, and 1,172 cm(-1) (tyrosine); 758 cm(-1) (tryptophan); 725, 782, 1,337, and 1,578 cm(-1) (adenine, cytosine plus uracil, adenine, and adenine plus guanine, respectively); 1,097 cm(-1) (carbohydrates); and 1,127, 1,450, and 2,932 cm(-1) (lipids) compared with untreated controls. Lemongrass oil treatments were the most effective in degrading cellular components. Scanning electron microscopy of palmarosa and lemongrass-oil-treated cells showed rupture of cell walls and cell debris but no degradation was noted for eucalyptus-oil-treated cells. Palmarosa- and lemongrass-oil-treated cells were positively stained with uranyl acetate when viewed by transmission electron microscopy whereas controls and eucalyptus-oil-treated cells were negatively stained, indicating that the cell membranes were intact. The viability of eucalyptus-oil-treated cells was confirmed by cell culture following treatment. Micro-Raman spectroscopy is a powerful tool which can be further employed to better understand effects of fumigants and other bactericides on bacterial cells. PMID:21899389

  4. Biomimicking Nano-Micro Binary Polymer Brushes for Smart Cell Orientation and Adhesion Control.

    PubMed

    Chen, Lina; Xie, Zhuang; Gan, Tiansheng; Wang, Yi; Zhang, Guangzhao; Mirkin, Chad A; Zheng, Zijian

    2016-07-01

    A new biomimetic surface named nano-micro binary polymer brushes is fabricated by large-area bench-top dip-pen nanodisplacement lithography technique. It is composed of gelatin-modified poly(glycidyl methacrylate) nanolines which are spaced by microstripes of poly(N-isopropylacrylamide). Cells are not only adhered and oriented well on the re-used surface, but also detachable from the surface with well-preserved extracellular matrix and aligned morphology. PMID:27184011

  5. Raman-Ramsey multizone spectroscopy in a pure rubidium vapor cell

    SciTech Connect

    Failache, H.; Lenci, L.; Lezama, A.

    2010-02-15

    In view of application to a miniaturized spectroscopy system, we consider an optical setup that splits a laser beam into several parallel narrow light sheets allowing an effective beam expansion and consequently longer atom-light interaction times. We analyze the multizone coherent population trapping (MZCPT) spectroscopy of alkali-metal-vapor atoms, without buffer gas, in the presence of a split light beam. We show that the MZCPT signal is largely insensitive to intensity broadening. Experimentally observed spectra are in qualitative agreement with the predictions of a simplified model that describes each spectrum as an integral over the atomic velocity distribution of Ramsey multizone spectra.

  6. Determination of inorganic and total mercury by vapor generation atomic absorption spectrometry using different temperatures of the measurement cell

    NASA Astrophysics Data System (ADS)

    Kaercher, Luiz Eduardo; Goldschmidt, Fabiane; Paniz, José Neri Gottfried; de Moraes Flores, Érico Marlon; Dressler, Valderi Luiz

    2005-06-01

    A simple and inexpensive laboratory-built flow injection vapor generation system coupled to atomic absorption spectrometry (FI-VG AAS) for inorganic and total mercury determination has been developed. It is based on the vapor generation of total mercury and a selective detection of Hg 2 + or total mercury by varying the temperature of the measurement cell. Only the inorganic mercury is measured when the quartz cell is at room temperature, and when the cell is heated to 650 °C or higher the total Hg concentration is measured. The organic Hg concentration in the sample is calculated from the difference between the total Hg and Hg 2 + concentrations. Parameters such as the type of acid (HCl or HNO 3) and its concentration, reductant (NaBH 4) concentration, carrier solution (HCl) flow rate, carrier gas flow rate, sample volume and quartz cell temperature, which influence FI-VG AAS system performance, were systematically investigated. The optimized conditions for Hg 2 + and total Hg determinations were: 1.0 mol l - 1 HCl as carrier solution, carrier flow rate of 3.5 ml min - 1 , 0.1% (m/v) NaBH 4, reductant flow rate of 1.0 ml min - 1 and carrier gas flow rate of 200 ml min - 1 . The relative standard deviation (RSD) is lower than 5.0% for a 1.0 μg l - 1 Hg solution and the limit of quantification (LOQ, 10 s) is 55 ng g - 1 . Certified samples of dogfish muscle (DORM-1 and DORM-2) and non-certified fish samples were analyzed, using a 6.0 mol l - 1 HCl solution for analyte extraction. The Hg 2 + and CH 3Hg + concentrations found were in agreement with certified ones.

  7. H19 derived microRNA-675 regulates cell proliferation and migration through CDK6 in glioma

    PubMed Central

    Li, Chao; Lei, Bingxi; Huang, Shuaibin; Zheng, Meiguang; Liu, Zhenghao; Li, Zhongjun; Deng, Yuefei

    2015-01-01

    The long non-coding RNA (LncRNA) H19 is one of the most highly abundant and conserved transcripts involved in the mammalian development and tumorigenesis. H19 is expressed in both embryonic cells and tumor cells, but its physical and pathological functions still need to be further studied. Our results showed that microRNA-675, a microRNA in the first exon of H19, expressed in glioma. Over-expression of microRNA-675 in a range of glioma cell lines resulted in their immoderate proliferation and migration. In addition, H19 derived microRNA-675 was down-regulated in the glioma, and CDK6, a pivotal regulator in cell cycle, was a target of microRNA-675. The survival of glioma patients with low CDK6 expression significantly increased as compared to patients with high CDK6 expression. Moreover, the CDK6 expression was inversely correlated with microRNA-675 expression in the glioma. Our results suggest that H19 derived microRNA-675 may regulate giloma cell proliferation and migration through CDK6, and predict a poor prognosis of glioma patients. PMID:26692922

  8. Magnetic Nano- and Micro- Particles in Living Cells: Kinetics and Fluctuations

    NASA Astrophysics Data System (ADS)

    Pease, C.; Chiang, N.; Pierce, C.; Muthusamy, N.; Sooryakumar, R.

    2015-03-01

    Functional nano and micro materials have recently been used not only as diagnostic tools for extracellular studies but also as intracellular drug delivery vehicles and as internal probes of the cell. To realize proper cellular applications, it is important not only to achieve efficient delivery of these materials to targeted cells, but also to control their movement and activity within the confines of the cell. In this presentation, superparamagnetic nano and micro particles are utilized as probes, with their responses to weak external magnetic fields enabling them to be maneuvered within a cell. In order to generate the required local magnetic fields needed for manipulation, the fields emanating from microscopic domain walls stabilized on patterned surface profiles are used in conjunction with weak external magnetic fields to create mobile traps that can localize and transport the internalized particle. Preliminary findings on creating the mobile traps suitable for applications to probe the interior of cells, and the responses, both Brownian fluctuations and directed motion, of particles ranging in size from 200 nm to 1 micron within HS-5 cells will be presented. Future applications to probe cellular behavior within the framework of emerging biomaterials will be discussed.

  9. Business Case for a Micro-Combined Heat and Power Fuel Cell System in Commercial Applications

    SciTech Connect

    Brooks, Kriston P.; Makhmalbaf, Atefe; Anderson, David M.; Amaya, Jodi P.; Pilli, Siva Prasad; Srivastava, Viraj; Upton, Jaki F.

    2013-10-30

    Combined heat and power fuel cell systems (CHP-FCSs) provide consistent electrical power and hot water with greater efficiency and lower emissions than alternative sources. These systems can be used either as baseload, grid-connected, or as off-the-grid power sources. This report presents a business case for CHP-FCSs in the range of 5 to 50 kWe. Systems in this power range are considered micro-CHP-FCS. For this particular business case, commercial applications rather than residential or industrial are targeted. To understand the benefits of implementing a micro-CHP-FCS, the characteristics that determine their competitive advantage must first be identified. Locations with high electricity prices and low natural gas prices are ideal locations for micro-CHP-FCSs. Fortunately, these high spark spread locations are generally in the northeastern area of the United States and California where government incentives are already in place to offset the current high cost of the micro-CHP-FCSs. As a result of the inherently high efficiency of a fuel cell and their ability to use the waste heat that is generated as a CHP, they have higher efficiency. This results in lower fuel costs than comparable alternative small-scale power systems (e.g., microturbines and reciprocating engines). A variety of markets should consider micro-CHP-FCSs including those that require both heat and baseload electricity throughout the year. In addition, the reliable power of micro-CHP-FCSs could be beneficial to markets where electrical outages are especially frequent or costly. Greenhouse gas emission levels from micro-CHP-FCSs are 69 percent lower, and the human health costs are 99.9 percent lower, than those attributed to conventional coal-fired power plants. As a result, FCSs can allow a company to advertise as environmentally conscious and provide a bottom-line sales advantage. As a new technology in the early stages of adoption, micro-CHP-FCSs are currently more expensive than alternative

  10. Biology of childhood germ cell tumours, focussing on the significance of microRNAs

    PubMed Central

    Murray, M J; Nicholson, J C; Coleman, N

    2015-01-01

    Genomic and protein-coding transcriptomic data have suggested that germ cell tumours (GCTs) of childhood are biologically distinct from those of adulthood. Global messenger RNA profiles segregate malignant GCTs primarily by histology, but then also by age, with numerous transcripts showing age-related differential expression. Such differences are likely to account for the heterogeneous clinico-pathological behaviour of paediatric and adult malignant GCTs. In contrast, as global microRNA signatures of human tumours reflect their developmental lineage, we hypothesized that microRNA profiles would identify common biological abnormalities in all malignant GCTs owing to their presumed shared origin from primordial germ cells. MicroRNAs are short, non-protein-coding RNAs that regulate gene expression via translational repression and/or mRNA degradation. We showed that all malignant GCTs over-express the miR-371–373 and miR-302/367 clusters, regardless of patient age, histological subtype or anatomical tumour site. Furthermore, bioinformatic approaches and subsequent Gene Ontology analysis revealed that these two over-expressed microRNAs clusters co-ordinately down-regulated genes involved in biologically significant pathways in malignant GCTs. The translational potential of this finding has been demonstrated with the detection of elevated serum levels of miR-371–373 and miR-302/367 microRNAs at the time of malignant GCT diagnosis, with levels falling after treatment. The tumour-suppressor let-7 microRNA family has also been shown to be universally down-regulated in malignant GCTs, because of abundant expression of the regulatory gene LIN28. Low let-7 levels resulted in up-regulation of oncogenes including MYCN, AURKB and LIN28 itself, the latter through a direct feedback mechanism. Targeting LIN28, or restoring let-7 levels, both led to effective inhibition of this pathway. In summary, paediatric malignant GCTs show biological differences from their adult

  11. Cell-specific expression of artificial microRNAs targeting essential genes exhibit potent antitumor effect on hepatocellular carcinoma cells

    PubMed Central

    Mao, Chenyu; Liu, Hao; Chen, Ping; Ye, Jingjia; Teng, Lisong; Jia, Zhenyu; Cao, Jiang

    2015-01-01

    To achieve specific and potent antitumor effect of hepatocyte carcinoma cells, replication defective adenoviral vectors, namely rAd/AFP-amiRG, rAd/AFP-amiRE and rAd/AFP-amiRP, were constructed which were armed with artificial microRNAs (amiRs) targeting essential functional genes glyceraldehyde-3-phosphate dehydrogenase, eukaryotic translation initiation factor 4E and DNA polymerase α respectively under the control of a recombinant promoter comprised of human α-fetoprotein enhancer and basal promoter. The AFP enhancer/promoter showed specific high transcription activity in AFP-positive HCC cells Hep3B, HepG2 and SMMC7721, while low in AFP-negative cell Bcap37. All artificial microRNAs exhibited efficient knockdown of target genes. Decreased ATP production and protein synthesis was observed in rAd/AFP-amiRG and rAd/AFP-amiRE treated HCC cells. All three recombinant adenoviruses showed efficient blockage of cell cycle progression and significant suppression of HCC cells in vitro. In nude mice model bearing Hep3B xenograft, administration of rAd/AFP-amiRG showed potent antitumor effect. The strategy of tumor-specific knockdown of genes essential for cell survival and proliferation may suggest a novel promising approach for HCC gene therapy. PMID:25691059

  12. Development of Anodic Flux and Temperature Controlling System for Micro Direct Methanol Fuel Cell

    NASA Astrophysics Data System (ADS)

    Li, M. M.; Liu, C.; Liang, J. S.; Wu, C. B.; Xu, Z.

    2006-10-01

    Micro Direct Methanol Fuel Cell (μDMFC) is a kind of newly developed power sources, which effective apparatus for its performance evaluation is still in urgent need at present. In this study, a testing system was established for the purpose of testing the continuous working performance such as micro flux and temperature of μDMFC. In view of the temperature controlling for micro-flux liquid fuel, a heating block with labyrinth-like single pass channel inside for heating up the methanol solution was fabricated. A semiconductorrefrigerating chip was utilized to heat and cool the liquid flow during testing procedures. On the other hand, the two channels of a high accuracy double-channel syringe pump that can suck and pump in turn so as to transport methanol solution continuously was adopted. Based on the requirements of wide-ranged temperature and micro flux controlling, the solenoid valves and the correlative component were used. A hydraulic circuit, which can circulate the fed methanol cold to hot in turn, has also been constructed to test the fatigue life of the μDMFC. The automatic control was actualized by software module written with Visual C++. Experimental results show that the system is perfect in stability and it may provide an important and advanced evaluation apparatus to satisfy the needs for real time performance testing of μDMFC.

  13. microRNAs as Pharmacological Targets in Endothelial Cell Function and Dysfunction

    PubMed Central

    Chamorro-Jorganes, Aránzazu; Araldi, Elisa; Suárez, Yajaira

    2013-01-01

    Endothelial cell dysfunction is a term which implies the dysregulation of normal endothelial cell functions, including impairment of the barrier functions, control of vascular tone, disturbance of proliferative, migratory and morphogenic capacities of endothelial cells, as well as control of leukocyte trafficking. MicroRNAs (miRNAs) are short non-coding RNAs that have emerged as critical regulators of gene expression acting predominantly at the post-transcriptional level. This review summarizes the latest insights in the identification of endothelial-specific miRNAs and their targets, as well as their roles in controlling endothelial cell functions in both autocrine and paracrine manner. In addition, we discuss the therapeutic potential for the treatment of endothelial cell dysfunction and associated vascular pathophysiological conditions. PMID:23603154

  14. Cell-free microRNAs in blood and other body fluids, as cancer biomarkers.

    PubMed

    Ortiz-Quintero, Blanca

    2016-06-01

    The discovery of cell-free microRNAs (miRNAs) in serum, plasma and other body fluids has yielded an invaluable potential source of non-invasive biomarkers for cancer and other non-malignant diseases. miRNAs in the blood and other body fluids are highly stable in biological samples and are resistant to environmental conditions, such as freezing, thawing or enzymatic degradation, which makes them convenient as potential biomarkers. In addition, they are more easily sampled than tissue miRNAs. Altered levels of cell-free miRNAs have been found in every type of cancer analysed, and increasing evidence indicates that they may participate in carcinogenesis by acting as cell-to-cell signalling molecules. This review summarizes the biological characteristics and mechanisms of release of cell-free miRNAs that make them promising candidates as non-invasive biomarkers of cancer. PMID:27218664

  15. MicroRNA-183 suppresses retinoblastoma cell growth, invasion and migration by targeting LRP6.

    PubMed

    Wang, Jianwen; Wang, Xiaochun; Li, Zhongji; Liu, Hongtao; Teng, Yan

    2014-03-01

    Our study demonstrates the downregulation of microRNA-183 (miR-183) in retinoblastoma (RB) tissues and RB cell lines compared with normal retinal tissues. The ectopic expression of miR-183 in the RB cell lines Y79, SO-RB50 and WERI-RB1 suppresses cell viability, migration and invasion. Furthermore, the Wnt co-receptor low-density lipoprotein receptor-related protein 6 (LRP6) was identified as a new target of miR-183, and restoration of the expression of LRP6 rescues the effects induced by miR-183 in RB cells. These results indicate that miR-183 targets and downregulates LRP6 in the growth, migration and invasion of RB cells. PMID:24289859

  16. Micro-patterning of Mammalian Cells on Suspended MEMS Resonant Sensors for Long-Term Growth Measurements

    PubMed Central

    Corbin, Elise A.; Dorvel, Brian R.; Millet, Larry J.; King, William P.; Bashir, Rashid

    2014-01-01

    MEMS resonant mass sensors can measure the mass of individual cells, though long-term growth measurements are limited by the movement of cells off the sensor area. Micro-patterning techniques are a powerful approach to control the placement of individual cells in an arrayed format. In this work we present a method for micro-patterning cells on fully suspended resonant sensors through select functionalization and passivation of the chip surface. This method combines high-resolution photolithography with a blanket transfer technique for applying photoresist to avoid damaging the sensors. Cells are constrained to the patterned collagen area on the sensor by pluronic acting as a cell adhesion blocker. This micro-patterning method enables long-term growth measurements, which is demonstrated by a measurement of the change in mass of a human breast cancer cell over 18 h. PMID:24535001

  17. microRNA-25 Inhibits Cell Apoptosis of Human Gastric Adenocarcinoma Cell Line AGS via Regulating CCNE1 and MYC

    PubMed Central

    Zhang, Yong; Peng, Zheng; Zhao, Yunshan; Chen, Lin

    2016-01-01

    Background Gastric carcinoma is the second leading cause of cancer death. microRNAs play vital roles in regulating expression of related oncogenes. microRNA-25 (miR-25) has been found to be up-regulated in gastric carcinoma. However, its roles in affecting cell apoptosis of gastric carcinoma and the related mechanism remain elusive. This study aimed to uncover the influences of miR-25 on gastric carcinoma cell apoptosis and the possible functional mechanisms involved. Material/Methods Human gastric adenocarcinoma cell line AGS was used and transfected with lentivirus containing miR-25-specifc inhibitor sponge or expression vector to analyze the effects of miR-25. Results miR-25 had higher expression in AGS than in human gastric epithelial cell line GES-1 (P<0.01). Inhibition of miR-25 by its sponge in AGS cells resulted in suppressed cell viability (P<0.01) and promoted cell apoptosis (P<0.01), while overexpression of miR-25 abrogated these effects (P<0.01 and P<0.05), indicating that miR-25 can promote cell viability and inhibit cell apoptosis in AGS cells. Expression analysis of related factors by Western blot showed that inhibiting miR-25 led to the up-regulation of F-box and WD repeat domain-containing 7 (FBXW7, P<0.01) and the down-regulation of FBXW7 substrates, cyclin E1 (CCNE1, P<0.01), and v-myc avian myelocytomatosis viral oncogene homolog (MYC, P<0.001). Conclusions These results indicate that miR-25 has anti-apoptosis roles in AGS cells, possibly via inhibiting FBXW7 and thus promoting oncogenes, such as CCNE1 and MYC. This study provides basic evidence for using miR-25 as a possible therapeutic target in treating gastric carcinoma. PMID:27120728

  18. Collapse and revival of a Dicke-type coherent narrowing in potassium vapor confined in a nanometric thin cell

    NASA Astrophysics Data System (ADS)

    Sargsyan, Armen; Pashayan-Leroy, Yevgenya; Leroy, Claude; Sarkisyan, David

    2016-04-01

    A nanometer-thin cell (in the direction of laser beam propagation) has been elaborated with the thickness of the atomic vapor column varying smoothly in the range of L=50-1500 {nm}. The cell allows one to study the behavior of the resonance absorption over the D 1 line of potassium atoms by varying the laser intensity and the cell thickness (from L=λ /2 to L=2λ with the step λ /2 where λ =770 {nm} is the resonant wavelength of the laser). It is shown that despite the huge Doppler broadening (\\gt 0.9 {GHz} at the cell temperature 170{}\\circ {{C}}), at low laser intensities a narrowing of the resonance absorption spectrum is observed for L=λ /2 (∼ 120 {MHz} at FWHM) and L=3/2λ , whereas for L=λ and L=2λ the spectrum broadens. At moderate laser intensities narrowband velocity selective optical pumping (VSOP) resonances appear at L=λ and L=2λ with the linewidth close to the natural one. A comparison with saturated absorption spectra obtained in a 1.4 cm-sized K cell is presented. The developed theoretical model well describes the experiment.

  19. Cell shape-dependent shear stress on adherent cells in a micro-physiologic system as revealed by FEM.

    PubMed

    Pfister, C; Bozsak, C; Wolf, P; Demmel, F; Brischwein, M

    2015-05-01

    Flow-induced shear stress on adherent cells leads to biochemical signaling and mechanical responses of the cells. To determine the flow-induced shear stress on adherent cells cultured in a micro-scaled reaction chamber, we developed a suitable finite element method model. The influence of the most important parameters-cell shape, cell density, shear modulus and fluid velocity-was investigated. Notably, the cell shape strongly influences the resulting shear stress. Long and smooth cells undergo lower shear stress than more rounded cells. Changes in the curvature of the cells lead to stress peaks and single cells experience higher shear stress values than cells of a confluent monolayer. The computational results of the fluid flow simulation were validated experimentally. We also analyzed the influence of flow-induced shear stress on the metabolic activity and shape of L929, a mouse fibroblast cell line, experimentally. The results indicate that threshold stress values for continuous flow conditions cannot be transferred to quasi static flow conditions interrupted by short fluid exchange events. PMID:25856467

  20. Exposure to Endocrine Disruptor Induces Transgenerational Epigenetic Deregulation of MicroRNAs in Primordial Germ Cells

    PubMed Central

    Brieño-Enríquez, Miguel A.; García-López, Jesús; Cárdenas, David B.; Guibert, Sylvain; Cleroux, Elouan; Děd, Lukas; Hourcade, Juan de Dios; Pěknicová, Jana; Weber, Michael; del Mazo, Jesús

    2015-01-01

    In mammals, germ cell differentiation is initiated in the Primordial Germ Cells (PGCs) during fetal development. Prenatal exposure to environmental toxicants such as endocrine disruptors may alter PGC differentiation, development of the male germline and induce transgenerational epigenetic disorders. The anti-androgenic compound vinclozolin represents a paradigmatic example of molecule causing transgenerational effects on germ cells. We performed prenatal exposure to vinclozolin in mice and analyzed the phenotypic and molecular changes in three successive generations. A reduction in the number of embryonic PGCs and increased rate of apoptotic cells along with decrease of fertility rate in adult males were observed in F1 to F3 generations. Blimp1 is a crucial regulator of PGC differentiation. We show that prenatal exposure to vinclozolin deregulates specific microRNAs in PGCs, such as miR-23b and miR-21, inducing disequilibrium in the Lin28/let-7/Blimp1 pathway in three successive generations of males. As determined by global maps of cytosine methylation, we found no evidence for prominent changes in DNA methylation in PGCs or mature sperm. Our data suggest that embryonic exposure to environmental endocrine disruptors induces transgenerational epigenetic deregulation of expression of microRNAs affecting key regulatory pathways of germ cells differentiation. PMID:25897752

  1. Regulation of mitochondrial morphology and cell cycle by microRNA-214 targeting Mitofusin2.

    PubMed

    Bucha, Sudha; Mukhopadhyay, Debashis; Bhattacharyya, Nitai Pada

    2015-10-01

    Huntington's disease (HD) is an autosomal dominant neurodegenerative disease caused by the increase in CAG repeats beyond 36 at the exon1 of the gene Huntingtin (HTT). Among the various dysfunctions of biological processes in HD, transcription deregulation due to abnormalities in actions of transcription factors has been considered to be one of the important pathological conditions. In addition, deregulation of microRNA (miRNA) expression has been described in HD. Earlier, expression of microRNA-214 (miR-214) has been shown to increase in HD cell models and target HTT gene; the expression of the later being inversely correlated to that of miR-214. In the present communication, we observed that the expressions of several HTT co-expressed genes are modulated by exogenous expression of miR-214 or by its mutant. Among several HTT co-expressed genes, MFN2 was shown to be the direct target of miR-214. Exogenous expression of miR-214, repressed the expression of MFN2, increased the distribution of fragmented mitochondria and altered the distribution of cells in different phases of cell cycle. In summary, we have shown that increased expression of miR-214 observed in HD cell model could target MFN2, altered mitochondrial morphology and deregulated cell cycle. Inhibition of miR-214 could be a possible target of intervention in HD pathogenesis. PMID:26307536

  2. Bone marrow stromal cell adhesion and morphology on micro- and sub-micropatterned titanium.

    PubMed

    Cipriano, Aaron F; De Howitt, Natalie; Gott, Shannon C; Miller, Christopher; Rao, Masaru P; Liu, Huinan

    2014-04-01

    The objective of this study was to investigate the adhesion and morphology of bone marrow derived stromal cells (BMSCs) on bulk titanium (Ti) substrates with precisely-patterned surfaces consisting of groove-based gratings with groove widths ranging from 50 micro m down to 0.5 micro m (500 nm). Although it is well known that certain surface patterning enhances osteoblast (bone-forming cell) functions, past studies on cell-pattern interactions reported in the literature have heavily relied on surface patterning on materials with limited clinical relevance for orthopedic applications, such as polymeric substrates. The clinical need for improving osseointegration and juxtaposed bone formation around load-bearing Ti implants motivated this in vitro study. BMSCs were selected as model cells due to their important role in bone regeneration. The results showed significantly greater BMSC adhesion density and more favorable cell morphology on sub-micropatterned gratings when compared with larger micropatterned gratings and non-patterned control surfaces after both 24 hr and 72 hr cultures. We observed increasing cellular alignment and elongation with decreasing feature size. We also identified two distinctive cellular morphologies: Type I-Attached and spread cells that elongated along the pattern axes; and Type II-Superficially adhered round cells. Sub-micropatterned gratings demonstrated significantly greater Type I cell density than the non-patterned control, and lower Type II cell density than the larger micropatterned gratings. Collectively, these results suggest potential for rationally designing nano-scale surface topography on Ti implants to improve osseointegration. PMID:24734518

  3. Enhanced current and power density of micro-scale microbial fuel cells with ultramicroelectrode anodes

    NASA Astrophysics Data System (ADS)

    Ren, Hao; Rangaswami, Sriram; Lee, Hyung-Sool; Chae, Junseok

    2016-09-01

    We present a micro-scale microbial fuel cell (MFC) with an ultramicroelectrode (UME) anode, with the aim of creating a miniaturized high-current/power-density converter using carbon-neutral and renewable energy sources. Micro-scale MFCs have been studied for more than a decade, yet their current and power densities are still an order of magnitude lower than those of their macro-scale counterparts. In order to enhance the current/power densities, we engineer a concentric ring-shaped UME, with a width of 20 μm, to facilitate the diffusion of ions in the vicinity of the micro-organisms that form biofilm on the UME. The biofilm extends approximately 15 μm from the edge of the UME, suggesting the effective biofilm area increases. Measured current/power densities per the effective area and the original anode area are 7.08  ±  0.01 A m‑2 & 3.09  ±  0.04 W m‑2 and 17.7  ±  0.03 A m‑2 & 7.72  ±  0.09 W m‑2, respectively. This is substantially higher than any prior work in micro-scale MFCs, and very close, or even higher, to that of macro-scale MFCs. A Coulombic efficiency, a measure of how efficiently an MFC harvests electrons from donor substrate, of 70%, and an energy conversion efficiency of 17% are marked, highlighting the micro-scale MFC as an attractive alternative within the existing energy conversion portfolio.

  4. MicroRNA-Offset RNA Alters Gene Expression and Cell Proliferation

    PubMed Central

    Zhao, Jin; Schnitzler, Gavin R.; Iyer, Lakshmanan K.; Aronovitz, Mark J.; Baur, Wendy E.; Karas, Richard H.

    2016-01-01

    MicroRNA-offset RNAs (moRs) were first identified in simple chordates and subsequently in mouse and human cells by deep sequencing of short RNAs. MoRs are derived from sequences located immediately adjacent to microRNAs (miRs) in the primary miR (pri-miR). Currently moRs are considered to be simply a by-product of miR biosynthesis that lack biological activity. Here we show for the first time that a moR is biologically active. We demonstrate that endogenous or over-expressed moR-21 significantly alters gene expression and inhibits the proliferation of vascular smooth muscle cells (VSMC). In addition, we find that miR-21 and moR-21 may regulate different genes in a given pathway and can oppose each other in regulating certain genes. We report that there is a “seed region” of moR-21 as well as a “seed match region” in the target gene 3’UTR that are indispensable for moR-21-mediated gene down-regulation. We further demonstrate that moR-21-mediated gene repression is Argonaute 2 (Ago2) dependent. Taken together, these findings provide the first evidence that microRNA offset RNA alters gene expression and is biologically active. PMID:27276022

  5. MicroRNA-302 switch to identify and eliminate undifferentiated human pluripotent stem cells

    PubMed Central

    Parr, Callum J. C.; Katayama, Shota; Miki, Kenji; Kuang, Yi; Yoshida, Yoshinori; Morizane, Asuka; Takahashi, Jun; Yamanaka, Shinya; Saito, Hirohide

    2016-01-01

    The efficiency of pluripotent stem cell differentiation is highly variable, often resulting in heterogeneous populations that contain undifferentiated cells. Here we developed a sensitive, target-specific, and general method for removing undesired cells before transplantation. MicroRNA-302a-5p (miR-302a) is highly and specifically expressed in human pluripotent stem cells and gradually decreases to basal levels during differentiation. We synthesized a new RNA tool, miR-switch, as a live-cell reporter mRNA for miR-302a activity that can specifically detect human induced pluripotent stem cells (hiPSCs) down to a spiked level of 0.05% of hiPSCs in a heterogeneous population and can prevent teratoma formation in an in vivo tumorigenicity assay. Automated and selective hiPSC-elimination was achieved by controlling puromycin resistance using the miR-302a switch. Our system uniquely provides sensitive detection of pluripotent stem cells and partially differentiated cells. In addition to its ability to eliminate undifferentiated cells, miR-302a switch also holds great potential in investigating the dynamics of differentiation and/or reprograming of live-cells based on intracellular information. PMID:27608814

  6. MicroRNA-302 switch to identify and eliminate undifferentiated human pluripotent stem cells.

    PubMed

    Parr, Callum J C; Katayama, Shota; Miki, Kenji; Kuang, Yi; Yoshida, Yoshinori; Morizane, Asuka; Takahashi, Jun; Yamanaka, Shinya; Saito, Hirohide

    2016-01-01

    The efficiency of pluripotent stem cell differentiation is highly variable, often resulting in heterogeneous populations that contain undifferentiated cells. Here we developed a sensitive, target-specific, and general method for removing undesired cells before transplantation. MicroRNA-302a-5p (miR-302a) is highly and specifically expressed in human pluripotent stem cells and gradually decreases to basal levels during differentiation. We synthesized a new RNA tool, miR-switch, as a live-cell reporter mRNA for miR-302a activity that can specifically detect human induced pluripotent stem cells (hiPSCs) down to a spiked level of 0.05% of hiPSCs in a heterogeneous population and can prevent teratoma formation in an in vivo tumorigenicity assay. Automated and selective hiPSC-elimination was achieved by controlling puromycin resistance using the miR-302a switch. Our system uniquely provides sensitive detection of pluripotent stem cells and partially differentiated cells. In addition to its ability to eliminate undifferentiated cells, miR-302a switch also holds great potential in investigating the dynamics of differentiation and/or reprograming of live-cells based on intracellular information. PMID:27608814

  7. Instrumental noise estimates stabilize and quantify endothelial cell micro-impedance barrier function parameter estimates

    SciTech Connect

    English, Anthony E; Moy, Alan B; Kruse, Kara L; Ward, Richard C; Kirkpatrick, Stacy S; GoldmanM.D., Mitchell H

    2009-04-01

    A novel transcellular micro-impedance biosensor, referred to as the electric cell-substrate impedance sensor or ECIS, has become increasingly applied to the study and quantification of endothelial cell physiology. In principle, frequency dependent impedance measurements obtained from this sensor can be used to estimate the cell cell and cell matrix impedance components of endothelial cell barrier function based on simple geometric models. Few studies, however, have examined the numerical optimization of these barrier function parameters and established their error bounds. This study, therefore, illustrates the implementation of a multi-response Levenberg Marquardt algorithm that includes instrumental noise estimates and applies it to frequency dependent porcine pulmonary artery endothelial cell impedance measurements. The stability of cell cell, cell matrix and membrane impedance parameter estimates based on this approach is carefully examined, and several forms of parameter instability and refinement illustrated. Including frequency dependent noise variance estimates in the numerical optimization reduced the parameter value dependence on the frequency range of measured impedances. The increased stability provided by a multi-response non-linear fit over one-dimensional algorithms indicated that both real and imaginary data should be used in the parameter optimization. Error estimates based on single fits and Monte Carlo simulations showed that the model barrier parameters were often highly correlated with each other. Independently resolving the different parameters can, therefore, present a challenge to the experimentalist and demand the use of non-linear multivariate statistical methods when comparing different sets of parameters.

  8. Regulation of MicroRNAs, and the Correlations of MicroRNAs and Their Targeted Genes by Zinc Oxide Nanoparticles in Ovarian Granulosa Cells

    PubMed Central

    Zhao, Yong; Li, Lan; Min, Ling-Jiang; Zhu, Lian-Qin; Sun, Qing-Yuan; Zhang, Hong-Fu; Liu, Xin-Qi; Zhang, Wei-Dong; Ge, Wei; Wang, Jun-Jie; Liu, Jing-Cai

    2016-01-01

    Zinc oxide (ZnO) nanoparticles (NPs) have been applied in numerous industrial products and personal care products like sunscreens and cosmetics. The released ZnO NPs from consumer and household products into the environment might pose potential health issues for animals and humans. In this study the expression of microRNAs and the correlations of microRNAs and their targeted genes in ZnO NPs treated chicken ovarian granulosa cells were investigated. ZnSO4 was used as the sole Zn2+ provider to differentiate the effects of NPs from Zn2+. It was found that ZnO-NP-5 μg/ml specifically regulated the expression of microRNAs involved in embryonic development although ZnO-NP-5 μg/ml and ZnSO4-10 μg/ml treatments produced the same intracellular Zn concentrations and resulted in similar cell growth inhibition. And ZnO-NP-5 μg/ml also specifically regulated the correlations of microRNAs and their targeted genes. This is the first investigation that intact NPs in ZnO-NP-5 μg/ml treatment specifically regulated the expression of microRNAs, and the correlations of microRNAs and their targeted genes compared to that by Zn2+. This expands our knowledge for biological effects of ZnO NPs and at the same time it raises the health concerns that ZnO NPs might adversely affect our biological systems, even the reproductive systems through regulation of specific signaling pathways. PMID:27196542

  9. Regulation of MicroRNAs, and the Correlations of MicroRNAs and Their Targeted Genes by Zinc Oxide Nanoparticles in Ovarian Granulosa Cells.

    PubMed

    Zhao, Yong; Li, Lan; Min, Ling-Jiang; Zhu, Lian-Qin; Sun, Qing-Yuan; Zhang, Hong-Fu; Liu, Xin-Qi; Zhang, Wei-Dong; Ge, Wei; Wang, Jun-Jie; Liu, Jing-Cai; Hao, Zhi-Hui

    2016-01-01

    Zinc oxide (ZnO) nanoparticles (NPs) have been applied in numerous industrial products and personal care products like sunscreens and cosmetics. The released ZnO NPs from consumer and household products into the environment might pose potential health issues for animals and humans. In this study the expression of microRNAs and the correlations of microRNAs and their targeted genes in ZnO NPs treated chicken ovarian granulosa cells were investigated. ZnSO4 was used as the sole Zn2+ provider to differentiate the effects of NPs from Zn2+. It was found that ZnO-NP-5 μg/ml specifically regulated the expression of microRNAs involved in embryonic development although ZnO-NP-5 μg/ml and ZnSO4-10 μg/ml treatments produced the same intracellular Zn concentrations and resulted in similar cell growth inhibition. And ZnO-NP-5 μg/ml also specifically regulated the correlations of microRNAs and their targeted genes. This is the first investigation that intact NPs in ZnO-NP-5 μg/ml treatment specifically regulated the expression of microRNAs, and the correlations of microRNAs and their targeted genes compared to that by Zn2+. This expands our knowledge for biological effects of ZnO NPs and at the same time it raises the health concerns that ZnO NPs might adversely affect our biological systems, even the reproductive systems through regulation of specific signaling pathways. PMID:27196542

  10. Fabrication of Planar Heterojunction Perovskite Solar Cells by Controlled Low-Pressure Vapor Annealing.

    PubMed

    Li, Yanbo; Cooper, Jason K; Buonsanti, Raffaella; Giannini, Cinzia; Liu, Yi; Toma, Francesca M; Sharp, Ian D

    2015-02-01

    A new method for achieving high efficiency planar CH3NH3I3-xClx perovskite photovoltaics, based on a low pressure, reduced temperature vapor annealing is demonstrated. Heterojunction devices based on this hybrid halide perovskite exhibit a top PCE of 16.8%, reduced J-V hysteresis, and highly repeatable performance without need for a mesoporous or nanocrystalline metal oxide layer. Our findings demonstrate that large hysteresis is not an inherent feature of planar heterojunctions, and that efficient charge extraction can be achieved with uniform halide perovskite materials with desired composition. X-ray diffraction, valence band spectroscopy, and transient absorption measurements of these thin films reveal that structural modifications induced by chlorine clearly dominate over chemical and electronic doping effects, without affecting the Fermi level or photocarrier lifetime in the material. PMID:26261969

  11. In Vivo HIV-1 Cell-to-Cell Transmission Promotes Multicopy Micro-compartmentalized Infection.

    PubMed

    Law, Kenneth M; Komarova, Natalia L; Yewdall, Alice W; Lee, Rebecca K; Herrera, Olga L; Wodarz, Dominik; Chen, Benjamin K

    2016-06-21

    HIV-1 infection is enhanced by adhesive structures that form between infected and uninfected T cells called virological synapses (VSs). This mode of transmission results in the frequent co-transmission of multiple copies of HIV-1 across the VS, which can reduce sensitivity to antiretroviral drugs. Studying HIV-1 infection of humanized mice, we measured the frequency of co-transmission and the spatiotemporal organization of infected cells as indicators of cell-to-cell transmission in vivo. When inoculating mice with cells co-infected with two viral genotypes, we observed high levels of co-transmission to target cells. Additionally, micro-anatomical clustering of viral genotypes within lymphoid tissue indicates that viral spread is driven by local processes and not a diffuse viral cloud. Intravital splenic imaging reveals that anchored HIV-infected cells induce arrest of interacting, uninfected CD4(+) T cells to form Env-dependent cell-cell conjugates. These findings suggest that HIV-1 spread between immune cells can be anatomically localized into infectious clusters. PMID:27292632

  12. Mesenchymal stem cells use extracellular vesicles to outsource mitophagy and shuttle microRNAs

    PubMed Central

    Phinney, Donald G.; Di Giuseppe, Michelangelo; Njah, Joel; Sala, Ernest; Shiva, Sruti; St Croix, Claudette M.; Stolz, Donna B.; Watkins, Simon C.; Di, Y. Peter; Leikauf, George D.; Kolls, Jay; Riches, David W. H.; Deiuliis, Giuseppe; Kaminski, Naftali; Boregowda, Siddaraju V.; McKenna, David H.; Ortiz, Luis A.

    2015-01-01

    Mesenchymal stem cells (MSCs) and macrophages are fundamental components of the stem cell niche and function coordinately to regulate haematopoietic stem cell self-renewal and mobilization. Recent studies indicate that mitophagy and healthy mitochondrial function are critical to the survival of stem cells, but how these processes are regulated in MSCs is unknown. Here we show that MSCs manage intracellular oxidative stress by targeting depolarized mitochondria to the plasma membrane via arrestin domain-containing protein 1-mediated microvesicles. The vesicles are then engulfed and re-utilized via a process involving fusion by macrophages, resulting in enhanced bioenergetics. Furthermore, we show that MSCs simultaneously shed micro RNA-containing exosomes that inhibit macrophage activation by suppressing Toll-like receptor signalling, thereby de-sensitizing macrophages to the ingested mitochondria. Collectively, these studies mechanistically link mitophagy and MSC survival with macrophage function, thereby providing a physiologically relevant context for the innate immunomodulatory activity of MSCs. PMID:26442449

  13. Mesenchymal stem cells use extracellular vesicles to outsource mitophagy and shuttle microRNAs.

    PubMed

    Phinney, Donald G; Di Giuseppe, Michelangelo; Njah, Joel; Sala, Ernest; Shiva, Sruti; St Croix, Claudette M; Stolz, Donna B; Watkins, Simon C; Di, Y Peter; Leikauf, George D; Kolls, Jay; Riches, David W H; Deiuliis, Giuseppe; Kaminski, Naftali; Boregowda, Siddaraju V; McKenna, David H; Ortiz, Luis A

    2015-01-01

    Mesenchymal stem cells (MSCs) and macrophages are fundamental components of the stem cell niche and function coordinately to regulate haematopoietic stem cell self-renewal and mobilization. Recent studies indicate that mitophagy and healthy mitochondrial function are critical to the survival of stem cells, but how these processes are regulated in MSCs is unknown. Here we show that MSCs manage intracellular oxidative stress by targeting depolarized mitochondria to the plasma membrane via arrestin domain-containing protein 1-mediated microvesicles. The vesicles are then engulfed and re-utilized via a process involving fusion by macrophages, resulting in enhanced bioenergetics. Furthermore, we show that MSCs simultaneously shed micro RNA-containing exosomes that inhibit macrophage activation by suppressing Toll-like receptor signalling, thereby de-sensitizing macrophages to the ingested mitochondria. Collectively, these studies mechanistically link mitophagy and MSC survival with macrophage function, thereby providing a physiologically relevant context for the innate immunomodulatory activity of MSCs. PMID:26442449

  14. Distinct microRNA signatures in human lymphocyte subsets and enforcement of the naive state in CD4+ T cells by the microRNA miR-125b.

    PubMed

    Rossi, Riccardo L; Rossetti, Grazisa; Wenandy, Lynn; Curti, Serena; Ripamonti, Anna; Bonnal, Raoul J P; Birolo, Roberto Sciarretta; Moro, Monica; Crosti, Maria C; Gruarin, Paola; Maglie, Stefano; Marabita, Francesco; Mascheroni, Debora; Parente, Valeria; Comelli, Mario; Trabucchi, Emilio; De Francesco, Raffaele; Geginat, Jens; Abrignani, Sergio; Pagani, Massimiliano

    2011-08-01

    MicroRNAs are small noncoding RNAs that regulate gene expression post-transcriptionally. Here we applied microRNA profiling to 17 human lymphocyte subsets to identify microRNA signatures that were distinct among various subsets and different from those of mouse lymphocytes. One of the signature microRNAs of naive CD4+ T cells, miR-125b, regulated the expression of genes encoding molecules involved in T cell differentiation, including IFNG, IL2RB, IL10RA and PRDM1. The expression of synthetic miR-125b and lentiviral vectors encoding the precursor to miR-125b in naive lymphocytes inhibited differentiation to effector cells. Our data provide an 'atlas' of microRNA expression in human lymphocytes, define subset-specific signatures and their target genes and indicate that the naive state of T cells is enforced by microRNA. PMID:21706005

  15. A versatile automated platform for micro-scale cell stimulation experiments.

    PubMed

    Sinha, Anupama; Jebrail, Mais J; Kim, Hanyoup; Patel, Kamlesh D; Branda, Steven S

    2013-01-01

    Study of cells in culture (in vitro analysis) has provided important insight into complex biological systems. Conventional methods and equipment for in vitro analysis are well suited to study of large numbers of cells (≥ 10(5)) in milliliter-scale volumes (≥ 0.1 ml). However, there are many instances in which it is necessary or desirable to scale down culture size to reduce consumption of the cells of interest and/or reagents required for their culture, stimulation, or processing. Unfortunately, conventional approaches do not support precise and reproducible manipulation of micro-scale cultures, and the microfluidics-based automated systems currently available are too complex and specialized for routine use by most laboratories. To address this problem, we have developed a simple and versatile technology platform for automated culture, stimulation, and recovery of small populations of cells (100-2,000 cells) in micro-scale volumes (1-20 μl). The platform consists of a set of fibronectin-coated microcapillaries ("cell perfusion chambers"), within which micro-scale cultures are established, maintained, and stimulated; a digital microfluidics (DMF) device outfitted with "transfer" microcapillaries ("central hub"), which routes cells and reagents to and from the perfusion chambers; a high-precision syringe pump, which powers transport of materials between the perfusion chambers and the central hub; and an electronic interface that provides control over transport of materials, which is coordinated and automated via pre-determined scripts. As an example, we used the platform to facilitate study of transcriptional responses elicited in immune cells upon challenge with bacteria. Use of the platform enabled us to reduce consumption of cells and reagents, minimize experiment-to-experiment variability, and re-direct hands-on labor. Given the advantages that it confers, as well as its accessibility and versatility, our platform should find use in a wide variety of

  16. Expression and regulatory effects of microRNA-182 in osteosarcoma cells: A pilot study

    PubMed Central

    BIAN, DONG-LIN; WANG, XUE-MEI; HUANG, KUN; ZHAI, QI-XI; YU, GUI-BO; WU, CHENG-HUA

    2016-01-01

    The aim of the present study was to evaluate the expression level of microRNA-182 (miRNA-182) in human osteosarcoma (OS) MG-63 cells and OS tissues, and to elucidate the effect of miRNA-182 on the biological activity of tumors. In the present study, the expression of miRNA-182 in human OS MG-63 cells, OS tissues and normal osteoblast hFOB1.19 cells was determined using quantitative polymerase chain reaction. Subsequently, a miRNA-182 mimic and inhibitor were utilized to regulate the expression level of this miRNA in MG-63 cells. Cell viability and proliferation were examined using cell counting kit-8 assays, and cell apoptosis was detected by flow cytometry. Cell invasion and migration assays were performed using Transwell chambers to analyze the biological functions of miRNA-182 in vitro. The present study demonstrated that the expression level of miRNA-182 in MG-63 cells and OS tissues was significantly increased compared with the hFOB1.19 cell line (P<0.05). The present study successfully performed cell transfections of miRNA-182 inhibitor and miRNA-182 mimic into MG-63 cells and achieved the desired transfection efficiency. The present study confirmed that upregulation of miRNA-182 promotes cell apoptosis and inhibits cell viability, proliferation, invasion and migration. The present findings additionally demonstrated that miRNA-182 is a tumor suppressor gene in OS. Therefore, regulating the expression of miRNA-182 may affect the biological behavior of OS cells, which suggests a potential role for miRNA-182 in molecular therapy for malignant tumors. PMID:27123060

  17. Material- and feature-dependent effects on cell adhesion to micro injection moulded medical polymers.

    PubMed

    Choi, Seong Ying; Habimana, Olivier; Flood, Peter; Reynaud, Emmanuel G; Rodriguez, Brian J; Zhang, Nan; Casey, Eoin; Gilchrist, Michael D

    2016-09-01

    Two polymers, polymethylmethacrylate (PMMA) and cyclic olefin copolymer (COC), containing a range of nano- to micron- roughness surfaces (Ra 0.01, 0.1, 0.4, 1.0, 2.0, 3.2 and 5.0μm) were fabricated using electrical discharge machining (EDM) and replicated using micro injection moulding (μIM). Polymer samples were characterized using optical profilometry, atomic force microscopy (AFM) and water surface contact angle. Cell adhesion tests were carried out using bacterial Pseudomonas fluorescens and mammalian Madin-Darby Canine Kidney (MDCK) cells to determine the effect of surface hydrophobicity, surface roughness and stiffness. It is found that there are features which gave insignificant differences (feature-dependent effect) in cell adhesion, albeit a significant difference in the physicochemical properties (material-dependent effect) of substrata. In bacterial cell adhesion, the strongest feature-dependence is found at Ra 0.4μm surfaces, with material-dependent effects strongest at Ra 0.01μm. Ra 0.1μm surfaces exhibited strongest feature-dependent effects and Ra 5.0μm has strongest material-dependent effects on mammalian cell adhesion. Bacterial cell adhesion is found to be favourable to hydrophobic surfaces (COC), with the lowest adhesion at Ra 0.4μm for both materials. Mammalian cell adhesion is lowest in Ra 0.1μm and highest in Ra 1.0μm, and generally favours hydrophilic surfaces (PMMA). These findings can be used as a basis for developing medical implants or microfluidic devices using micro injection moulding for diagnostic purposes, by tuning the cell adhesion on different areas containing different surface roughnesses on the diagnostic microfluidic devices or medical implants. PMID:27137802

  18. MicroRNA-128 coordinately targets Polycomb Repressor Complexes in glioma stem cells

    PubMed Central

    Peruzzi, Pierpaolo; Bronisz, Agnieszka; Nowicki, Michal O.; Wang, Yan; Ogawa, Daisuke; Price, Richard; Nakano, Ichiro; Kwon, Chang-Hyuk; Hayes, Josie; Lawler, Sean E.; Ostrowski, Michael C.; Chiocca, E. Antonio; Godlewski, Jakub

    2013-01-01

    Background The Polycomb Repressor Complex (PRC) is an epigenetic regulator of transcription whose action is mediated by 2 protein complexes, PRC1 and PRC2. PRC is oncogenic in glioblastoma, where it is involved in cancer stem cell maintenance and radioresistance. Methods We used a set of glioblastoma patient samples, glioma stem cells, and neural stem cells from a mouse model of glioblastoma. We characterized gene/protein expression and cellular phenotypes by quantitative PCR/Western blotting and clonogenic, cell-cycle, and DNA damage assays. We performed overexpression/knockdown studies by lentiviral infection and microRNA/small interfering RNA oligonucleotide transfection. Results We show that microRNA-128 (miR-128) directly targets mRNA of SUZ12, a key component of PRC2, in addition to BMI1, a component of PRC1 that we previously showed as a target as well. This blocks the partially redundant functions of PRC1/PRC2, thereby significantly reducing PRC activity and its associated histone modifications. MiR-128 and SUZ12/BMI1 show opposite expression in human glioblastomas versus normal brain and in glioma stemlike versus neural stem cells. Furthermore, miR-128 renders glioma stemlike cells less radioresistant by preventing the radiation-induced expression of both PRC components. Finally, miR-128 expression is significantly reduced in neural stem cells from the brain of young, presymptomatic mice in our mouse model of glioblastoma. This suggests that loss of miR-128 expression in brain is an early event in gliomagenesis. Moreover, knockdown of miR-128 expression in nonmalignant mouse and human neural stem cells led to elevated expression of PRC components and increased clonogenicity. Conclusions MiR-128 is an important suppressor of PRC activity, and its absence is an early event in gliomagenesis. PMID:23733246

  19. Resolving the nanostructure of plasma-enhanced chemical vapor deposited nanocrystalline SiOx layers for application in solar cells

    NASA Astrophysics Data System (ADS)

    Klingsporn, M.; Kirner, S.; Villringer, C.; Abou-Ras, D.; Costina, I.; Lehmann, M.; Stannowski, B.

    2016-06-01

    Nanocrystalline silicon suboxides (nc-SiOx) have attracted attention during the past years for the use in thin-film silicon solar cells. We investigated the relationships between the nanostructure as well as the chemical, electrical, and optical properties of phosphorous, doped, nc-SiO0.8:H fabricated by plasma-enhanced chemical vapor deposition. The nanostructure was varied through the sample series by changing the deposition pressure from 533 to 1067 Pa. The samples were then characterized by X-ray photoelectron spectroscopy, spectroscopic ellipsometry, Raman spectroscopy, aberration-corrected high-resolution transmission electron microscopy, selected-area electron diffraction, and a specialized plasmon imaging method. We found that the material changed with increasing pressure from predominantly amorphous silicon monoxide to silicon dioxide containing nanocrystalline silicon. The nanostructure changed from amorphous silicon filaments to nanocrystalline silicon filaments, which were found to cause anisotropic electron transport.

  20. ZnO/Cu(InGa)Se.sub.2 solar cells prepared by vapor phase Zn doping

    DOEpatents

    Ramanathan, Kannan; Hasoon, Falah S.; Asher, Sarah E.; Dolan, James; Keane, James C.

    2007-02-20

    A process for making a thin film ZnO/Cu(InGa)Se.sub.2 solar cell without depositing a buffer layer and by Zn doping from a vapor phase, comprising: depositing Cu(InGa)Se.sub.2 layer on a metal back contact deposited on a glass substrate; heating the Cu(InGa)Se.sub.2 layer on the metal back contact on the glass substrate to a temperature range between about 100.degree. C. to about 250.degree. C.; subjecting the heated layer of Cu(InGa)Se.sub.2 to an evaporant species from a Zn compound; and sputter depositing ZnO on the Zn compound evaporant species treated layer of Cu(InGa)Se.sub.2.

  1. The effect of temperature on chromium vaporization and oxide scale growth on interconnect steels for Solid Oxide Fuel Cells

    NASA Astrophysics Data System (ADS)

    Falk-Windisch, Hannes; Svensson, Jan Erik; Froitzheim, Jan

    2015-08-01

    Chromium vaporization and oxide scale growth are probably the two most important degradation mechanisms associated with the interconnect in Solid Oxide Fuel Cells (SOFCs) when Cr2O3-forming alloys are used as the interconnect material. This study examines the influence of temperature on both mechanisms. Two commercially available steels; Crofer 22 H and Sanergy HT, were isothermally exposed at 650, 750 and 850 °C in an air-3% H2O atmosphere with a high flow rate. Volatile chromium species were collected using the denuder technique. The microstructure of thermally grown oxide scales was characterized using Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Analysis (EDX) and X-Ray Diffraction (XRD). The findings of this study show that although Cr evaporation is reduced with lower temperature, its relative importance compared to oxide scale growth is greater.

  2. Algorithm for evaluation of temperature distribution of a vapor cell in a diode-pumped alkali laser system (part II).

    PubMed

    Han, Juhong; Wang, You; Cai, He; An, Guofei; Zhang, Wei; Xue, Liangping; Wang, Hongyuan; Zhou, Jie; Jiang, Zhigang; Gao, Ming

    2015-04-01

    With high efficiency and small thermally-induced effects in the near-infrared wavelength region, a diode-pumped alkali laser (DPAL) is regarded as combining the major advantages of solid-state lasers and gas-state lasers and obviating their main disadvantages at the same time. Studying the temperature distribution in the cross-section of an alkali-vapor cell is critical to realize high-powered DPAL systems for both static and flowing states. In this report, a theoretical algorithm has been built to investigate the features of a flowing-gas DPAL system by uniting procedures in kinetics, heat transfer, and fluid dynamic together. The thermal features and output characteristics have been simultaneously obtained for different gas velocities. The results have demonstrated the great potential of DPALs in the extremely high-powered laser operation. PMID:25968778

  3. MicroRNA-155 controls CD8+ T cell responses by regulating interferon signaling

    PubMed Central

    Gracias, Donald T.; Stelekati, Erietta; Hope, Jennifer L.; Boesteanu, Alina C.; Doering, Travis; Norton, Jillian; Mueller, Yvonne M.; Fraietta, Joseph A.; Wherry, E. John; Turner, Martin; Katsikis, Peter D.

    2013-01-01

    We show that microRNA-155 (miR-155) is upregulated in primary effector and effector memory CD8+ T cells but is low in naive and central memory cells. Anti-viral CD8+ T cell responses and viral clearance were impaired in miR-155 deficient (miR-155-KO) mice, and this defect was intrinsic to CD8+ T cells as miR-155-KO CD8+ T cells mounted greatly reduced primary and memory responses. Conversely, miR-155 overexpression augmented anti-viral CD8+ T cell responses in vivo. Gene expression profiling of miR-155-KO CD8+ T cells revealed increased type I interferon signaling and sensitivity. Inhibiting STAT1 or IRF7 increased miR-155-KO CD8+ T cell responses in vivo. We report a novel role for miR-155 in regulating IFN responsiveness and CD8+ T cell responses against pathogens in vivo. PMID:23603793

  4. High throughput assembly of spatially controlled 3D cell clusters on a micro/nanoplatform.

    PubMed

    Gallego-Perez, Daniel; Higuita-Castro, Natalia; Sharma, Sadhana; Reen, Rashmeet K; Palmer, Andre F; Gooch, Keith J; Lee, L James; Lannutti, John J; Hansford, Derek J

    2010-03-21

    Guided assembly of microscale tissue subunits (i.e. 3D cell clusters/aggregates) has found applications in cell therapy/tissue engineering, cell and developmental biology, and drug discovery. As cluster size and geometry are known to influence cellular responses, the ability to spatially control cluster formation in a high throughput manner could be advantageous for many biomedical applications. In this work, a micro- and nanofabricated platform was developed for this purpose, consisting of a soft-lithographically fabricated array of through-thickness microwells structurally bonded to a sheet of electrospun fibers. The microwells and fibers were manufactured from several polymers of biomedical interest. Human hepatocytes were used as model cells to demonstrate the ability of the platform to allow controlled cluster formation. In addition, the ability of the device to support studies on semi-controlled heterotypic interactions was demonstrated by co-culturing hepatocytes and fibroblasts. Preliminary experiments with other cells of interest (pancreatic cells, embryonic stem cells, and cardiomyocytes) were also conducted. Our platform possesses several advantages over previously developed microwell arrays: a more in vivo-like topographical stimulation of cells; better nutrient/waste exchange through the underlying nanofiber mat; and easy integration into standard two-chamber cell culture well systems. PMID:20221567

  5. Micro-environmentally restricted hybridoma cell growth within polysaccharide hydrogel microbeads.

    PubMed

    Pajic-Lijakovic, Ivana

    2013-01-01

    The mechanism of micro-environmentally restricted hybridoma cell growth caused by action of local mechanical compression stress generated within various polysaccharide hydrogel matrixes is estimated by comparing the growth of hybridoma cells within (1) 1.5% Ca-alginate microbeads from Bugarski et al. [in: Fundamentals of Animal Cells Immobilization and Microencapsulation, M.F.A. Goosen, ed., CRC Press, Boca Raton, FL, 1993, p. 267] and (2) 1.3% alginate-agarose microbeads from Shen et al. [Animal Cell Technology: Basic & Applied Aspects, H. Murakami ed., Kluwer Academic Publishers, The Netherlands, 1992, p. 173].Consideration of restricted cell growth dynamics based on developed kinetic model and kinetic 3D Monte Carlo simulation include: (1) changes the fraction of active proliferating cells in the exponential phase and (2) changes of non-proliferating cell concentration in the plateau phase.Higher value of the specific decrease of active fraction of proliferating cells κ is obtained for 1.3% alginate-agarose compared to 1.5% alginate microbeads. It corresponds to higher compression stress generated within hydrogel matrix during cell growth obtained for 1.3% alginate-agarose microbeads. PMID:23988708

  6. MicroRNAs are involved in the self-renewal and differentiation of cancer stem cells

    PubMed Central

    Wang, Zheng-ming; Du, Wen-jun; Piazza, Gary A; Xi, Yaguang

    2013-01-01

    MicroRNAs (miRNAs) are small non-coding RNA molecules, whose primary function is to regulate gene expression at the post-transcriptional/translational levels. MiRNAs play crucial roles in normal biological processes and are commonly dys-regulated in human diseases. Stem cells are regarded as the “mother” cells of all types of differentiated cells that comprise tissues and organs of the body. A novel hypothesis proposes that tumors are composed of heterogeneous cells derived from cancer stem cells, which have self-renewal and differentiation capabilities similar to those of normal stem cells. Cancer stem cells have been isolated and characterized from various tumors. Given recent studies supporting the critical regulatory roles of miRNAs in the self-renewal and differentiation of cancer stem cells, better understanding the functions of miRNAs will provide invaluable insights into the prevention of tumorigenesis and tumor progression. In this review, we will summarize the research progress in the study of miRNAs involved in the self-renewal and differentiation of cancer stem cells. PMID:24122008

  7. Synchrotron radiation X-ray micro-fluorescence: Protocol to study mesenchymal stem cells.

    PubMed

    Rezende, Karla Mayra; Bönecker, Marcelo; Perez, Carlos Alberto; Mantesso, Andrea

    2016-03-01

    The micro-X-ray fluorescence by synchrotron radiation (μ-XRF) is a method to determine the composition of tissues without destroying the samples. However, this technique has never been used for the analysis of mesenchymal stem cells (MSC). This study compared different protocols for fixing, storing, preserving, and establishing the correct numbers of dental derived MSC submitted to μ-XRF analysis. Stem cells were obtained from human dental tissue. After cell expansion, and MACS isolation, the samples were fixed and the following quantities of cells 1 × 10(4) to 1 × 10(7) were divided in two groups: G1: fixed in 4% paraformaldehyde diluted in phosphate-buffered saline solution, and G2: fixed in 4% paraformaldehyde diluted in MilliQ water. The G1 cells showed precipitation of chemical components from the solution resulting in the formation of salt crystals while G2 cells were clear and almost transparent in the sample holder. With regards to cells concentration, the best results occurred when four droplets of 1 × 10(7) cells were analyzed. This work shows that to identify and study the distribution of trace elements in MSC by μ-XRF, the best protocol is fixation in 4% paraformaldehyde diluted with MilliQ water at 4°C and a concentration of four incremental droplets of 1 × 10(7) cells. PMID:26749077

  8. MicroRNA-26a Promotes Regulatory T cells and Suppresses Autoimmune Diabetes in Mice.

    PubMed

    Ma, Hui; Zhang, Shoutao; Shi, Doufei; Mao, Yanhua; Cui, Jianguo

    2016-02-01

    Type-1 diabetes (TID) is an autoimmune disease in which the body's own immune cells attack islet β cells, the cells in the pancreas that produce and release the hormone insulin. Mir-26a has been reported to play functions in cellular differentiation, cell growth, cell apoptosis, and metastasis. However, the role of microRNA-26a (Mir-26a) in autoimmune TID has never been investigated. In our current study, we found that pre-Mir-26a (LV-26a)-treated mice had significantly longer normoglycemic time and lower frequency of autoreactive IFN-γ-producing CD4(+) cells compared with an empty lentiviral vector (LV-Con)-treated non-obese diabetic (NOD) mice. Mir-26a suppresses autoreactive T cells and expands Tregs in vivo and in vitro. Furthermore, in our adoptive transfer study, the groups receiving whole splenocytes and CD25-depleted splenocytes from LV-Con-treated diabetic NOD mice develop diabetes at 3 to 4 weeks of age. In comparison, mice injected with undepleted splenocytes obtained from LV-26a-treated reversal NOD mice develop diabetes after 6-8 weeks. And depletion of CD25(+) cells in the splenocytes of reversed mice abrogates the delay in diabetes onset. In conclusion, Mir-26a suppresses autoimmune diabetes in NOD mice in part through promoted regulatory T cells (Tregs) expression. PMID:26208605

  9. A micro-scale simulation of red blood cell passage through symmetric and asymmetric bifurcated vessels.

    PubMed

    Wang, Tong; Rongin, Uwitije; Xing, Zhongwen

    2016-01-01

    Blood exhibits a heterogeneous nature of hematocrit, velocity, and effective viscosity in microcapillaries. Microvascular bifurcations have a significant influence on the distribution of the blood cells and blood flow behavior. This paper presents a simulation study performed on the two-dimensional motions and deformation of multiple red blood cells in microvessels with diverging and converging bifurcations. Fluid dynamics and membrane mechanics were incorporated. Effects of cell shape, hematocrit, and deformability of the cell membrane on rheological behavior of the red blood cells and the hemodynamics have been investigated. It was shown that the blood entering the daughter branch with a higher flow rate tended to receive disproportionally more cells. The results also demonstrate that red blood cells in microvessels experienced lateral migration in the parent channel and blunted velocity profiles in both straight section and daughter branches, and this effect was influenced by the shape and the initial position of the cells, the hematocrit, and the membrane deformability. In addition, a cell free region around the tip of the confluence was observed. The simulation results are qualitatively consistent with existing experimental findings. This study may provide fundamental knowledge for a better understanding of hemodynamic behavior of micro-scale blood flow. PMID:26830454

  10. A micro-scale simulation of red blood cell passage through symmetric and asymmetric bifurcated vessels

    PubMed Central

    Wang, Tong; Rongin, Uwitije; Xing, Zhongwen

    2016-01-01

    Blood exhibits a heterogeneous nature of hematocrit, velocity, and effective viscosity in microcapillaries. Microvascular bifurcations have a significant influence on the distribution of the blood cells and blood flow behavior. This paper presents a simulation study performed on the two-dimensional motions and deformation of multiple red blood cells in microvessels with diverging and converging bifurcations. Fluid dynamics and membrane mechanics were incorporated. Effects of cell shape, hematocrit, and deformability of the cell membrane on rheological behavior of the red blood cells and the hemodynamics have been investigated. It was shown that the blood entering the daughter branch with a higher flow rate tended to receive disproportionally more cells. The results also demonstrate that red blood cells in microvessels experienced lateral migration in the parent channel and blunted velocity profiles in both straight section and daughter branches, and this effect was influenced by the shape and the initial position of the cells, the hematocrit, and the membrane deformability. In addition, a cell free region around the tip of the confluence was observed. The simulation results are qualitatively consistent with existing experimental findings. This study may provide fundamental knowledge for a better understanding of hemodynamic behavior of micro-scale blood flow. PMID:26830454

  11. A micro-scale simulation of red blood cell passage through symmetric and asymmetric bifurcated vessels

    NASA Astrophysics Data System (ADS)

    Wang, Tong; Rongin, Uwitije; Xing, Zhongwen

    2016-02-01

    Blood exhibits a heterogeneous nature of hematocrit, velocity, and effective viscosity in microcapillaries. Microvascular bifurcations have a significant influence on the distribution of the blood cells and blood flow behavior. This paper presents a simulation study performed on the two-dimensional motions and deformation of multiple red blood cells in microvessels with diverging and converging bifurcations. Fluid dynamics and membrane mechanics were incorporated. Effects of cell shape, hematocrit, and deformability of the cell membrane on rheological behavior of the red blood cells and the hemodynamics have been investigated. It was shown that the blood entering the daughter branch with a higher flow rate tended to receive disproportionally more cells. The results also demonstrate that red blood cells in microvessels experienced lateral migration in the parent channel and blunted velocity profiles in both straight section and daughter branches, and this effect was influenced by the shape and the initial position of the cells, the hematocrit, and the membrane deformability. In addition, a cell free region around the tip of the confluence was observed. The simulation results are qualitatively consistent with existing experimental findings. This study may provide fundamental knowledge for a better understanding of hemodynamic behavior of micro-scale blood flow.

  12. The expression and functional roles of microRNAs in stem cell differentiation

    PubMed Central

    Shim, Jiwon; Nam, Jin-Wu

    2016-01-01

    microRNAs (miRNAs) are key regulators of cell state transition and retention during stem cell proliferation and differentiation by post-transcriptionally downregulating hundreds of conserved target genes via seed-pairing in their 3’ untranslated region. In embryonic and adult stem cells, dozens of miRNAs that elaborately control stem cell processes by modulating the transcriptomic context therein have been identified. Some miRNAs accelerate the change of cell state into progenitor cell lineages—such as myoblast, myeloid or lymphoid progenitors, and neuro precursor stem cells—and other miRNAs decelerate the change but induce proliferative activity, resulting in cell state retention. This cell state choice can be controlled by endogenously or exogenously changing miRNA levels or by including or excluding target sites. This control of miRNA-mediated gene regulation could improve our understanding of stem cell biology and facilitate their development as therapeutic tools. [BMB Reports 2016; 49(1): 3-10] PMID:26497582

  13. MicroRNA-203 As a Stemness Inhibitor of Glioblastoma Stem Cells.

    PubMed

    Deng, Yifan; Zhu, Gang; Luo, Honghai; Zhao, Shiguang

    2016-08-31

    Glioblastoma stem cells (GBM-SCs) are believed to be a subpopulation within all glioblastoma (GBM) cells that are in large part responsible for tumor growth and the high grade of therapeutic resistance that is so characteristic of GBM. MicroRNAs (miR) have been implicated in regulating the expression of oncogenes and tumor suppressor genes in cancer stem cells, including GBM-SCs, and they are a potential target for cancer therapy. In the current study, miR-203 expression was reduced in CD133(+) GBM-SCs derived from six human GBM biopsies. MicroRNA-203 transfected GBM-SCs had reduced capacity for self-renewal in the cell sphere assay and increased expression of glial and neuronal differentiation markers. In addition, a reduced proliferation rate and an increased rate of apoptosis were observed. Therefore, miR-203 has the potential to reduce features of stemness, specifically in GBM-SCs, and is a logical target for GBM gene therapy. PMID:27484906

  14. Proteomic and microRNA data clarifying the effects of telomere shortening on cancer cells.

    PubMed

    Uziel, Orit; Lahav, Meir

    2015-03-01

    In a previous study, we have shown that shortening of telomeres by telomerase inhibition sensitized cancer cells to cisplatinum, slower their migration, increased DNA damage and impaired DNA repair [1]. In the following study, we present a network model combining microRNA and proteomic profiling attempting to decipher the molecular mechanism underlying the effect of shortened telomeres on the obtained phenotype of cancer cells [2]. The microRNA and proteomic data were used for a network model construction, which provided us with several nodal candidates that may potentially mediate the shortened-telomeres dependent features. These protein expressions were experimentally validated, supporting their potential central role in this system [2]. In this article, we delineate the full proteomic data and a microarray analyses performed on cells with shortened telomeres compared to their cognate parental intact telomere cells. The data is attached as excel files. In principle, clarifying the mechanism behind telomere shortened phenotype may facilitate novel therapeutics development and may also obviate the time consuming process of telomere shortening achieved by telomerase inhibition. PMID:26217705

  15. MicroRNA-203 As a Stemness Inhibitor of Glioblastoma Stem Cells

    PubMed Central

    Deng, Yifan; Zhu, Gang; Luo, Honghai; Zhao, Shiguang

    2016-01-01

    Glioblastoma stem cells (GBM-SCs) are believed to be a subpopulation within all glioblastoma (GBM) cells that are in large part responsible for tumor growth and the high grade of therapeutic resistance that is so characteristic of GBM. MicroRNAs (miR) have been implicated in regulating the expression of oncogenes and tumor suppressor genes in cancer stem cells, including GBM-SCs, and they are a potential target for cancer therapy. In the current study, miR-203 expression was reduced in CD133+ GBM-SCs derived from six human GBM biopsies. MicroRNA-203 transfected GBM-SCs had reduced capacity for self-renewal in the cell sphere assay and increased expression of glial and neuronal differentiation markers. In addition, a reduced proliferation rate and an increased rate of apoptosis were observed. Therefore, miR-203 has the potential to reduce features of stemness, specifically in GBM-SCs, and is a logical target for GBM gene therapy. PMID:27484906

  16. MicroRNA-181c targets Bcl-2 and regulates mitochondrial morphology in myocardial cells

    PubMed Central

    Wang, Hongjiang; Li, Jing; Chi, Hongjie; Zhang, Fan; Zhu, Xiaoming; Cai, Jun; Yang, Xinchun

    2015-01-01

    Apoptosis is an important mechanism for the development of heart failure. Mitochondria are central to the execution of apoptosis in the intrinsic pathway. The main regulator of mitochondrial pathway of apoptosis is Bcl-2 family which includes pro- and anti-apoptotic proteins. MicroRNAs are small noncoding RNA molecules that regulate gene expression by inhibiting mRNA translation and/or inducing mRNA degradation. It has been proposed that microRNAs play critical roles in the cardiovascular physiology and pathogenesis of cardiovascular diseases. Our previous study has found that microRNA-181c, a miRNA expressed in the myocardial cells, plays an important role in the development of heart failure. With bioinformatics analysis, we predicted that miR-181c could target the 3′ untranslated region of Bcl-2, one of the anti-apoptotic members of the Bcl-2 family. Thus, we have suggested that miR-181c was involved in regulation of Bcl-2. In this study, we investigated this hypothesis using the Dual-Luciferase Reporter Assay System. Cultured myocardial cells were transfected with the mimic or inhibitor of miR-181c. We found that the level of miR-181c was inversely correlated with the Bcl-2 protein level and that transfection of myocardial cells with the mimic or inhibitor of miR-181c resulted in significant changes in the levels of caspases, Bcl-2 and cytochrome C in these cells. The increased level of Bcl-2 caused by the decrease in miR-181c protected mitochondrial morphology from the tumour necrosis factor alpha-induced apoptosis. PMID:25898913

  17. Low-Temperature Process for Atomic Layer Chemical Vapor Deposition of an Al2O3 Passivation Layer for Organic Photovoltaic Cells.

    PubMed

    Kim, Hoonbae; Lee, Jihye; Sohn, Sunyoung; Jung, Donggeun

    2016-05-01

    Flexible organic photovoltaic (OPV) cells have drawn extensive attention due to their light weight, cost efficiency, portability, and so on. However, OPV cells degrade quickly due to organic damage by water vapor or oxygen penetration when the devices are driven in the atmosphere without a passivation layer. In order to prevent damage due to water vapor or oxygen permeation into the devices, passivation layers have been introduced through methods such as sputtering, plasma enhanced chemical vapor deposition, and atomic layer chemical vapor deposition (ALCVD). In this work, the structural and chemical properties of Al2O3 films, deposited via ALCVD at relatively low temperatures of 109 degrees C, 200 degrees C, and 300 degrees C, are analyzed. In our experiment, trimethylaluminum (TMA) and H2O were used as precursors for Al2O3 film deposition via ALCVD. All of the Al2O3 films showed very smooth, featureless surfaces without notable defects. However, we found that the plastic flexible substrate of an OPV device passivated with 300 degrees C deposition temperature was partially bended and melted, indicating that passivation layers for OPV cells on plastic flexible substrates need to be formed at temperatures lower than 300 degrees C. The OPV cells on plastic flexible substrates were passivated by the Al2O3 film deposited at the temperature of 109 degrees C. Thereafter, the photovoltaic properties of passivated OPV cells were investigated as a function of exposure time under the atmosphere. PMID:27483916

  18. Human amniotic epithelial cell feeder layers maintain human iPS cell pluripotency via inhibited endogenous microRNA-145 and increased Sox2 expression

    SciTech Connect

    Liu, Te; Cheng, Weiwei; Huang, Yongyi; Huang, Qin; Jiang, Lizhen; Guo, Lihe

    2012-02-15

    Currently, human induced pluripotent stem (iPS) cells were generated from patient or disease-specific sources and share the same key properties as embryonic stem cells. This makes them attractive for personalized medicine, drug screens or cellular therapy. Long-term cultivation and maintenance of normal iPS cells in an undifferentiated self-renewing state are a major challenge. Our previous studies have shown that human amniotic epithelial cells (HuAECs) could provide a good source of feeder cells for mouse and human embryonic stem cells, or spermatogonial stem cells, but the mechanism for this is unknown. Here, we examined the effect of endogenous microRNA-145 regulation on Sox2 expression in human iPS cells by HuAECs feeder cells regulation, and in turn on human iPS cells pluripotency. We found that human IPS cells transfected with a microRNA-145 mutant expressed Sox2 at high levels, allowing iPS to maintain a high level of AP activity in long-term culture and form teratomas in SCID mice. Expression of stem cell markers was increased in iPS transfected with the microRNA-145 mutant, compared with iPS was transfected with microRNA-145. Besides, the expression of Drosha proteins of the microRNA-processor complex, required for the generation of precursor pre-miRNA, was significantly increased in human iPS cells cultured on MEF but not on HuAECs. Taken together, these results suggest that endogenous Sox2 expression may be regulated by microRNA-145 in human iPS cells with HuAECs feeder cells, and Sox2 is a crucial component required for maintenance of them in an undifferentiated, proliferative state capable of self-renewal. Highlights: Black-Right-Pointing-Pointer microRNA-145 inhibits Sox2 expression in human iPS cells. Black-Right-Pointing-Pointer microRNA-145 suppresses the self-renewal and pluripotency of human iPS cells. Black-Right-Pointing-Pointer HuAECs regulate expression of microRNA-145 and Sox2 in human iPS cells. Black-Right-Pointing-Pointer HuAECs feeder

  19. MicroRNA let-7d regulates the TLX/microRNA-9 cascade to control neural cell fate and neurogenesis

    PubMed Central

    Zhao, Chunnian; Sun, GuoQiang; Ye, Peng; Li, Shengxiu; Shi, Yanhong

    2013-01-01

    MicroRNAs have important functions in the nervous system through post-transcriptional regulation of neurogenesis genes. Here we show that microRNA let-7d, which has been implicated in cocaine addiction and other neurological disorders, targets the neural stem cell regulator TLX. Overexpression of let-7d in vivo reduced neural stem cell proliferation and promoted premature neuronal differentiation and migration, a phenotype similar to those induced by TLX knockdown or overexpression of its negatively-regulated target, microRNA-9. We found a let-7d binding sequence in the tlx 3′ UTR and demonstrated that let-7d reduced TLX expression levels in neural stem cells, which in turn, up-regulated miR-9 expression. Moreover, co-expression of let-7d and TLX lacking its 3′ UTR in vivo restored neural stem cell proliferation and reversed the premature neuronal differentiation and migration. Therefore, manipulating let-7d and its downstream targets could be a novel strategy to unravel neurogenic signaling pathways and identify potential interventions for relevant neurological disorders. PMID:23435502

  20. 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

  1. Transient gene and microRNA expression profile changes of confluent human fibroblast cells in spaceflight.

    PubMed

    Zhang, Ye; Lu, Tao; Wong, Michael; Wang, Xiaoyu; Stodieck, Louis; Karouia, Fathi; Story, Michael; Wu, Honglu

    2016-06-01

    Microgravity, or an altered gravity environment different from the 1 g of the Earth, has been shown to influence global gene expression patterns and protein levels in cultured cells. However, most of the reported studies that have been conducted in space or by using simulated microgravity on the ground have focused on the growth or differentiation of these cells. It has not been specifically addressed whether nonproliferating cultured cells will sense the presence of microgravity in space. In an experiment conducted onboard the International Space Station, confluent human fibroblast cells were fixed after being cultured in space for 3 and 14 d, respectively, to investigate changes in gene and microRNA (miRNA) expression profiles in these cells. Results of the experiment showed that on d 3, both the flown and ground cells were still proliferating slowly, as measured by the percentage of Ki-67(+) cells. Gene and miRNA expression data indicated activation of NF-κB and other growth-related pathways that involve hepatocyte growth factor and VEGF as well as the down-regulation of the Let-7 miRNA family. On d 14, when the cells were mostly nonproliferating, the gene and miRNA expression profile of the flight sample was indistinguishable from that of the ground sample. Comparison of gene and miRNA expressions in the d 3 samples, with respect to d 14, revealed that most of the changes observed on d 3 were related to cell growth for both the flown and ground cells. Analysis of cytoskeletal changes via immunohistochemistry staining of the cells with antibodies for α-tubulin and fibronectin showed no difference between the flown and ground samples. Taken together, our study suggests that in true nondividing human fibroblast cells in culture, microgravity experienced in space has little effect on gene and miRNA expression profiles.-Zhang, Y., Lu, T., Wong, M., Wang, X., Stodieck, L., Karouia, F., Story, M., Wu, H. Transient gene and microRNA expression profile changes of

  2. Micro-textures for efficient light trapping and improved electrical performance in thin-film nanocrystalline silicon solar cells

    NASA Astrophysics Data System (ADS)

    Tan, Hairen; Psomadaki, Efthymia; Isabella, Olindo; Fischer, Marinus; Babal, Pavel; Vasudevan, Ravi; Zeman, Miro; Smets, Arno H. M.

    2013-10-01

    Micro-textures with large opening angles and smooth U-shape are applied to nanocrystalline silicon (nc-Si:H) solar cells. The micro-textured substrates result in higher open-circuit-voltage (Voc) and fill-factor (FF) than nano-textured substrates. For thick solar cells, high Voc and FF are maintained. Particularly, the Voc only drops from 564 to 541 mV as solar cell thickness increases from 1 to 5 μm. The improvement in electrical performance of solar cells is ascribed to the growth of dense nc-Si:H layers free from defective filaments on micro-textured substrates. Thereby, micromorph tandem solar cells with an initial efficiency of 13.3%, Voc = 1.464 V, and FF = 0.759 are obtained.

  3. Gas cell based on optical contacting for fundamental spectroscopy studies with initial reference absorption spectrum of H2O vapor at 1723 K and 0.0235 bar

    NASA Astrophysics Data System (ADS)

    Melin, Scott T.; Sanders, Scott T.

    2016-09-01

    A gas cell, using optically contacted sapphire windows to form a hot vapor seal, has been created for high temperature fundamental spectroscopy studies. It is designed to operate at temperatures from 280-2273 K and pressures from vacuum to 1.3 bar. Using the cell in conjunction with an external cavity diode laser spectrometer, a reference H2O vapor absorption spectrum at P=0.0235±0.0036 bar and T=1723±6 K was measured with 0.0001 cm-1 resolution over the 7326-7598 cm-1 range. Comparison of the measured spectrum to simulations reveals errors in both the HITEMP and BT2 databases. This work establishes heated static cell capabilities at temperatures well above the typical limit of approximately 1300 K set by quartz material properties. This paper addresses the design of the cell as well as the cell's limitations.

  4. Function and significance of MicroRNAs in benign and malignant human stem cells.

    PubMed

    Utikal, Jochen; Abba, Mohammed; Novak, Daniel; Moniuszko, Marcin; Allgayer, Heike

    2015-12-01

    MicroRNAs now not only represent a significant mechanism for post-transcriptional gene regulation, but have come to be appreciated as molecules with far reaching tentacles affecting diverse processes and pathologies by modulating amongst others, cellular gene expression, epigentic mechanisms, complex signaling cascades, cell-cell communication, the immune system and microenvironmental interactions between several cell types, tissues and organ systems. In this review, we systematically reflect on the impact of miRNAs on all types of benign and malignant human stem cells, looking at the roles they play in maintaining or changing the stem cell state, and review how aberrations of their expression and function within diverse types of stem cells orchestrate carcinogenesis and metastasis. As a conclusion, we consider it striking to see how similar some miR-driven mechanisms are between different types of stem cells and cancer cells, and how this might support hypotheses of miR-driven embryologic pathway reactivation in metastasis or propose putative functions of miRs in important novel cross-topic fields such as obesity and cancer. PMID:26192966

  5. HDL-transferred microRNA-223 regulates ICAM-1 expression in endothelial cells

    PubMed Central

    Tabet, Fatiha; Vickers, Kasey C.; Cuesta Torres, Luisa F.; Wiese, Carrie B.; Shoucri, Bassem M.; Lambert, Gilles; Catherinet, Claire; Prado-Lourenco, Leonel; Levin, Michael G.; Thacker, Seth; Sethupathy, Praveen; Barter, Philip J.; Remaley, Alan T.; Rye, Kerry-Anne

    2014-01-01

    High-density lipoproteins (HDL) have many biological functions, including reducing endothelial activation and adhesion molecule expression. We recently reported that HDL transport and deliver functional microRNAs (miRNA). Here we show that HDL suppresses expression of intercellular adhesion molecule 1 (ICAM-1) through the transfer of miR-223 to endothelial cells. After incubation of endothelial cells with HDL, mature miR-223 levels are significantly increased in endothelial cells and decreased on HDL. However, miR-223 is not transcribed in endothelial cells and is not increased in cells treated with HDL from miR-223−/− mice. HDL inhibit ICAM-1 protein levels, but not in cells pretreated with miR-223 inhibitors. ICAM-1 is a direct target of HDL-transferred miR-223 and this is the first example of an extracellular miRNA regulating gene expression in cells where it is not transcribed. Collectively, we demonstrate that HDL’s anti-inflammatory properties are conferred, in part, through HDL-miR-223 delivery and translational repression of ICAM-1 in endothelial cells. PMID:24576947

  6. MicroRNA-202 inhibits tumor progression by targeting LAMA1 in esophageal squamous cell carcinoma.

    PubMed

    Meng, Xiangrui; Chen, Xiaoqi; Lu, Peng; Ma, Wang; Yue, Dongli; Song, Lijie; Fan, Qingxia

    2016-05-13

    Esophageal squamous cell carcinoma (ESCC) is one of the most aggressive malignancies in the gastrointestinal tract. Emerging studies have indicated that microRNAs (miRNAs) are strongly implicated in the development and progression of ESCC. Here, we focused on the function and the underlying molecular mechanism of miR-202 in ESCC. The results showed that miR-202 was significantly down-regulated in ESCC tissues and cell lines. Overexpression of miR-202 in ECa-109 and KYSE-510 cells markedly suppressed cell proliferation and cell migration, and induced cell apoptosis. Furthermore, laminin α1 (LAMA1) expression was frequently positive in ESCC tissues and inversely correlated with miR-202 expression. Then we demonstrated that miR-202 targeted 3'-untranslated region (UTR) of LAMA1 and inhibited its protein expression. Additionally, LAMA1 overexpression rescued the proliferation inhibition and cell apoptosis elevation induced by miR-202. MiR-202 also inhibited the protein expression of p-FAK and p-Akt, which were all reversed by LAMA1 overexpression. Taken together, these findings suggest that miR-202 may function as a novel tumor suppressor in ESCC by repressing cell proliferation and migration, and its biological effects may attribute the inhibition of LAMA1-mediated FAK-PI3K-Akt signaling. PMID:27045085

  7. MicroRNAs in B-cells: from normal differentiation to treatment of malignancies

    PubMed Central

    Marques, Sara Correia; Laursen, Maria Bach; Bødker, Julie Støve; Kjeldsen, Malene Krag; Falgreen, Steffen; Schmitz, Alexander; Bøgsted, Martin; Johnsen, Hans Erik; Dybkaer, Karen

    2015-01-01

    MicroRNAs (miRNAs) are small non-coding RNAs that play important post-transcriptional regulatory roles in a wide range of biological processes. They are fundamental to the normal development of cells, and evidence suggests that the deregulation of specific miRNAs is involved in malignant transformation due to their function as oncogenes or tumor suppressors. We know that miRNAs are involved in the development of normal B-cells and that different B-cell subsets express specific miRNA profiles according to their degree of differentiation. B-cell-derived malignancies contain transcription signatures reminiscent of their cell of origin. Therefore, we believe that normal and malignant B-cells share features of regulatory networks controlling differentiation and the ability to respond to treatment. The involvement of miRNAs in these processes makes them good biomarker candidates. B-cell malignancies are highly prevalent, and the poor overall survival of patients with these malignancies demands an improvement in stratification according to prognosis and therapy response, wherein we believe miRNAs may be of great importance. We have critically reviewed the literature, and here we sum up the findings of miRNA studies in hematological cancers, from the development and progression of the disease to the response to treatment, with a particular emphasis on B-cell malignancies. PMID:25622103

  8. MicroRNAs transfer from human macrophages to hepato-carcinoma cells and inhibit proliferation.

    PubMed

    Aucher, Anne; Rudnicka, Dominika; Davis, Daniel M

    2013-12-15

    Recent research has indicated a new mode of intercellular communication facilitated by the movement of RNA between cells. There is evidence that RNA can transfer between cells in a multitude of ways, including in complex with proteins or lipids or in vesicles, including apoptotic bodies and exosomes. However, there remains little understanding of the function of nucleic acid transfer between human cells. In this article, we report that human macrophages transfer microRNAs (miRNAs) to hepato-carcinoma cells (HCCs) in a manner that required intercellular contact and involved gap junctions. Two specific miRNAs transferred efficiently between these cells--miR-142 and miR-223--and both were endogenously expressed in macrophages and not in HCCs. Transfer of these miRNAs influenced posttranscriptional regulation of proteins in HCCs, including decreased expression of reporter proteins and endogenously expressed stathmin-1 and insulin-like growth factor-1 receptor. Importantly, transfer of miRNAs from macrophages functionally inhibited proliferation of these cancerous cells. Thus, these data led us to propose that intercellular transfer of miRNA from immune cells could serve as a new defense against unwanted cell proliferation or tumor growth. PMID:24227773

  9. Regulation of Neuronal Cell Cycle and Apoptosis by MicroRNA 34a.

    PubMed

    Modi, Prashant Kumar; Jaiswal, Surbhi; Sharma, Pushkar

    2016-01-01

    The cell cycle of neurons remains suppressed to maintain the state of differentiation and aberrant cell cycle reentry results in loss of neurons, which is a feature in neurodegenerative disorders like Alzheimer's disease (AD). Present studies revealed that the expression of microRNA 34a (miR-34a) needs to be optimal in neurons, as an aberrant increase or decrease in its expression causes apoptosis. miR-34a keeps the neuronal cell cycle under check by preventing the expression of cyclin D1 and promotes cell cycle arrest. Neurotoxic amyloid β1-42 peptide (Aβ42) treatment of cortical neurons suppressed miR-34a, resulting in unscheduled cell cycle reentry, which resulted in apoptosis. The repression of miR-34a was a result of degradation of TAp73, which was mediated by aberrant activation of the MEK extracellular signal-regulated kinase (ERK) pathway by Aβ42. A significant decrease in miR-34a and TAp73 was observed in the cortex of a transgenic (Tg) mouse model of AD, which correlated well with cell cycle reentry observed in the neurons of these animals. Importantly, the overexpression of TAp73α and miR-34a reversed cell cycle-related neuronal apoptosis (CRNA). These studies provide novel insights into how modulation of neuronal cell cycle machinery may lead to neurodegeneration and may contribute to the understanding of disorders like AD. PMID:26459758

  10. Preliminary micro-Raman images of normal and malignant human skin cells

    NASA Astrophysics Data System (ADS)

    Short, Michael A.; Lui, Harvey; McLean, David I.; Zeng, Haishan; Chen, Michael X.

    2006-02-01

    Micro-Raman spectroscopy covering a frequency range from 200 to 4000 cm -1 was used to image human skin melanocytes and keratinocytes with a spatial resolution of 0.5 μm. The cells were either cultivated on glass microscope slides or were located within thin sections of skin biopsies mounted on low fluorescence BaF II. A commercially available system was used to obtain the spectra utilizing a x100 long working distance objective with a numerical aperture of 0.8, and a cooled CCD. Both 633 and 515 nm excitations were tried, although the latter proved to be more effcient at producing Raman emission mostly due to the 1/λ 4 dependence in light scattering. Fluorescence emission from the cells was surprisingly low. The excitation power at the sample was kept below about 2 mW to avoid damaging the cells; this was the limiting factor on how quickly a Raman image could be obtained. Despite this diffculty we were able to obtain Raman images with rich information about the spectroscopic and structural features within the cytoplasm and cell nuclei. Differences were observed between the Raman images of normal and malignant cells. Spectra from purified DNA, RNA, lipids, proteins and melanin were obtained and these spectra were compared with the skin cell spectra with the aim of understanding how they are distributed over a cell and how the distribution changes between different cells.

  11. Vector light shift averaging in paraffin-coated alkali vapor cells

    NASA Astrophysics Data System (ADS)

    Zhivun, Elena; Wickenbrock, Arne; Sudyka, Julia; Patton, Brian; Pustelny, Szymon; Budker, Dmitry

    2016-05-01

    Light shifts are an important source of noise and systematics in optically pumped magnetometers. We demonstrate that the long spin coherence time in paraffin-coated cells leads to spatial averaging of the light shifts over the entire cell volume. This renders the averaged light shift independent, under certain approximations, of the light-intensity distribution within the sensor cell. These results and the underlying mechanism can be extended to other spatially varying phenomena in anti-relaxation-coated cells with long coherence times.

  12. Vector light shift averaging in paraffin-coated alkali vapor cells.

    PubMed

    Zhivun, Elena; Wickenbrock, Arne; Sudyka, Julia; Patton, Brian; Pustelny, Szymon; Budker, Dmitry

    2016-07-11

    Light shifts are an important source of noise and systematics in optically pumped magnetometers. We demonstrate that the long spin-coherence time in paraffin-coated cells leads to spatial averaging of the vector light shift over the entire cell volume. This renders the averaged vector light shift independent, under certain approximations, of the light-intensity distribution within the sensor cell. Importantly, the demonstrated averaging mechanism can be extended to other spatially varying phenomena in anti-relaxation-coated cells with long coherence times. PMID:27410814

  13. MicroRNA-187 induces diffuse large B-cell lymphoma cell apoptosis via targeting BCL6

    PubMed Central

    HUANG, FANG; JIN, YAOFENG; WEI, YAFENG

    2016-01-01

    MicroRNAs (miRs) are endogenous non-coding RNAs that serve key functions in a wide range of biological processes, including cell growth, development, apoptosis and carcinogenesis. However, the association between miR-187 and B-cell lymphoma 6 (BCL6) has yet to be fully investigated in lymphoma cell apoptosis. The present study hypothesized that a post-translational mechanism may exist for BCL6 expression, which is regulated by miR-187 in lymphoma cells. The present study demonstrated that the expression of miR-187 in diffuse large B-cell lymphoma (DLBCL) cells was significantly decreased, and its expression was negatively correlated with BCL6 expression. It was also observed that miR-187 directly binds to the 3′-untranslated region of BCL6 mRNA and subsequently suppresses the expression of BCL6. Additionally, the induced expression of miR-187 significantly promoted DLBCL cell apoptosis in vitro. The drug sensitivity of human DLBCL SUDHL2 cells was increased following induction of miR-187 overexpression via an miR-187 mimic. In conclusion, the results of the present study suggest that the modulation of miR-187 expression in DLBCL cells may improve the sensitivity of chemotherapy through BCL6 targeting. PMID:27073562

  14. Passivation properties of aluminum oxide films deposited by mist chemical vapor deposition for solar cell applications

    NASA Astrophysics Data System (ADS)

    Miki, Shohei; Iguchi, Koji; Kitano, Sho; Hayakashi, Koki; Hotta, Yasushi; Yoshida, Haruhiko; Ogura, Atsushi; Satoh, Shin-ichi; Arafune, Koji

    2015-08-01

    Aluminum oxide (AlOx) films were deposited by mist chemical vapor deposition (MCVD) in air for p-type crystalline silicon, and the effects of the deposition temperature (Tdep) and AlOx film thickness on the maximum surface recombination velocities (Smax) were evaluated. It was found that Smax was improved with increasing Tdep. The AlOx film deposited at 400 °C exhibited the best Smax value of 2.8 cm/s, and the passivation quality was comparable to that of AlOx deposited by other vacuum-based techniques. Smax was also improved with increasing film thickness. When the film thickness was above 10 nm, Smax was approximately 10 cm/s. From the Fourier transform infrared spectra, it was found that the AlOx films deposited by MCVD consisted of an AlOx layer and a Si-diffused AlOx layer. In addition, it is important for the layers to be thick enough to obtain high-quality passivation.

  15. Regulation of microRNA function in somatic stem cell proliferation and differentiation

    PubMed Central

    Shenoy, Archana; Blelloch, Robert H.

    2015-01-01

    microRNAs (miRNAs) are important modulators of development. Owing to their ability to simultaneously silence hundreds of target genes, they have key roles in large-scale transcriptomic changes that occur during cell fate transitions. In somatic stem and progenitor cells — such as those involved in myogenesis, haematopoiesis, skin and neural development — miRNA function is carefully regulated to promote and stabilize cell fate choice. miRNAs are integrated within networks that form both positive and negative feedback loops. Their function is regulated at multiple levels, including transcription, biogenesis, stability, availability and/or number of target sites, as well as their cooperation with other miRNAs and RNA-binding proteins. Together, these regulatory mechanisms result in a refined molecular response that enables proper cellular differentiation and function. PMID:25118717

  16. MicroRNA-130a regulates cell malignancy by targeting RECK in chronic myeloid leukemia

    PubMed Central

    Li, Quan; Wu, Yaohui; Zhang, Jian; Yi, Tienan; Li, Weiming

    2016-01-01

    Emerging evidence has indicated that microRNAs are involved in tumor development and progression, acting as either tumor suppressors or oncogenes. In this study, we aimed to investigate the role of miR-130a in the pathogenesis of chronic myeloid leukemia (CML). Functional studies indicate that over-expression of miR-130a in A562 CML cells dramatically suppresses cell proliferation and induces cell apoptosis both in vitro and in vivo. Furthermore, we demonstrate that the transcriptional regulator RECK is a target of miR-130a. In conclusion, our study suggests that miR-130a may function as a novel tumor suppressor in CML, and its anti-oncogenic activity may involve the direct targeting and inhibition of RECK. PMID:27158382

  17. Electrochemical electron paramagnetic resonance utilizing loop gap resonators and micro-electrochemical cells.

    PubMed

    Tamski, Mika A; Macpherson, Julie V; Unwin, Patrick R; Newton, Mark E

    2015-09-28

    A miniaturised electrochemical cell design for Electron Paramagnetic Resonance (EPR) studies is reported. The cell incorporates a Loop Gap Resonator (LGR) for EPR investigation of electrochemically generated radicals in aqueous (and other large dielectric loss) samples and achieves accurate potential control for electrochemistry by using micro-wires as working electrodes. The electrochemical behaviour of the cell is analysed with COMSOL finite element models and the EPR sensitivity compared to a commercial TE011 cavity resonator using 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPOL) as a reference. The electrochemical EPR performance is demonstrated using the reduction of methyl viologen as a redox probe in both water and acetonitrile. The data reported herein suggest that sub-micromolar concentrations of radical species can be detected in aqueous samples with accurate potential control, and that subtle solution processes coupled to electron transfer, such as comproportionation reactions, can be studied quantitatively using EPR. PMID:26291423

  18. The role of microRNA in esophageal squamous cell carcinoma.

    PubMed

    Harada, Kazuto; Baba, Yoshifumi; Ishimoto, Takatsugu; Shigaki, Hironobu; Kosumi, Keisuke; Yoshida, Naoya; Watanabe, Masayuki; Baba, Hideo

    2016-06-01

    MicroRNAs (miRNA) are 22-nucleotide non-coding RNAs that post-transcriptionally regulate gene expression by base pairing to partially complementary sequences in the 3'-untranslated region of their target messenger RNA. Altered miRNA expression also changes the expression of oncogenes and tumor suppressors, affecting the proliferation, apoptosis, motility and invasibility of gastrointestinal cancer cells, including the cells of esophageal squamous cell carcinoma (ESCC). It has been suggested that various miRNA expression profiles may provide useful biomarkers and therapeutic targets, but to date few studies have been published on the role of miRNA in ESCC. In this review we summarize the identification and characterization of miRNAs involved in ESCC and discuss their potential as biomarkers and therapeutic targets. PMID:26794004

  19. Hydrogen generation from hydrides in millimeter scale reactors for micro proton exchange membrane fuel cell applications

    NASA Astrophysics Data System (ADS)

    Zhu, L.; Kim, D.; Kim, H.; Masel, R. I.; Shannon, M. A.

    This paper introduces and discusses the feasibility of millimeter scale powder packed-bed reactors using high energy density chemical hydrides for micro-PEM fuel cell applications. Two different reactors were designed and tested using LiBH 4, LiAlH 4, NaAlH 4 and CaH 2 hydride fuels. The mechanisms that limit the total yield of H 2 generated and impact the performance of the hydrogen generator are investigated in this paper, including density, solubility and porosity of the reaction byproducts. The volume expansion of the byproducts has significant effect on the total energy density of micro-hydrogen generators because the byproducts are left in the millimeter scale reactor after the reactions and the micro-hydrogen generators have limited fuel storage space. The SEM images of the reaction byproducts indicates that the byproducts of LiBH 4 can form a single solid mass that clogged the reaction vessel and limit the full utilization of the hydride. However, the byproducts of LiAlH 4 and CaH 2 reactions are non-agglomerated and they do not form impermeable mass. The experimental results show that the highest yield of hydrogen generation was achieved with LiAlH 4 and CaH 2 fuels.

  20. Idiosyncrasies of Physical Vapor Deposition Processes from Various Knudsen Cells for Quinacridone Thin Film Growth on Silicon Dioxide

    PubMed Central

    2015-01-01

    Thin films of quinacridone deposited by physical vapor deposition on silicon dioxide were investigated by thermal desorption spectroscopy (TDS), mass spectrometry (MS), atomic force microscopy (AFM), specular and grazing incidence X-ray diffraction (XRD, GIXD), and Raman spectroscopy. Using a stainless steel Knudsen cell did not allow the preparation of a pure quinacridone film. TDS and MS unambiguously showed that in addition to quinacridone, desorbing at about 500 K (γ-peak), significant amounts of indigo desorbed at about 420 K (β-peak). The existence of these two species on the surface was verified by XRD, GIXD, and Raman spectroscopy. The latter spectroscopies revealed that additional species are contained in the films, not detected by TDS. In the film mainly composed of indigo a species was identified which we tentatively attribute to carbazole. The film consisting of mainly quinacridone contained in addition p-sexiphenyl. The reason for the various decomposition species effusing from the metal Knudsen cell is the comparably high sublimation temperature of the hydrogen bonded quinacridone. With special experimental methods and by using glass Knudsen-type cells we were able to prepare films which exclusively consist of molecules either corresponding to the β-peak or the γ-peak. These findings are of relevance for choosing the proper deposition techniques in the preparation of quinacridone films in the context of organic electronic devices. PMID:26401189

  1. Micro-ultrasonic cleaving of cell clusters by laser-generated focused ultrasound and its mechanisms

    PubMed Central

    Baac, Hyoung Won; Lee, Taehwa; Guo, L. Jay

    2013-01-01

    Laser-generated focused ultrasound (LGFU) is a unique modality that can produce single-pulsed cavitation and strong local disturbances on a tight focal spot (<100 μm). We utilize LGFU as a non-contact, non-thermal, high-precision tool to fractionate and cleave cell clusters cultured on glass substrates. Fractionation processes are investigated in detail, which confirms distinct cell behaviors in the focal center and the periphery of LGFU spot. For better understanding of local disturbances under LGFU, we use a high-speed laser-flash shadowgraphy technique and then fully visualize instantaneous microscopic processes from the ultrasound wave focusing to the micro-bubble collapse. Based on these visual evidences, we discuss possible mechanisms responsible for the focal and peripheral disruptions, such as a liquid jet-induced wall shear stress and shock emissions due to bubble collapse. The ultrasonic micro-fractionation is readily available for in vitro cell patterning and harvesting. Moreover, it is significant as a preliminary step towards high-precision surgery applications in future. PMID:24010006

  2. Microvesicle-mediated Transfer of MicroRNA-150 from Monocytes to Endothelial Cells Promotes Angiogenesis*

    PubMed Central

    Li, Jing; Zhang, Yujing; Liu, Yuchen; Dai, Xin; Li, Wenyang; Cai, Xing; Yin, Yuan; Wang, Qiang; Xue, Yunxing; Wang, Cheng; Li, Dameng; Hou, Dongxia; Jiang, Xiaohong; Zhang, Junfeng; Zen, Ke; Chen, Xi; Zhang, Chen-Yu

    2013-01-01

    Recent studies by our group and others show that microRNAs can be actively secreted into the extracellular environment through microvesicles (MVs) and function as secretory signaling molecules that influence the recipient cell phenotypes. Here we investigate the role of monocyte-secreted miR-150 in promoting the capillary tube formation of endothelial cells and in enhancing angiogenesis. In vitro capillary tube formation and in vivo angiogenesis assays showed that monocyte-derived MVs have strong pro-angiogenic activities. By depleting miR-150 from monocytic MVs and increasing miR-150 in MVs derived from cells that normally contain low levels of miR-150, we further demonstrated that the miR-150 content accounted for the pro-angiogenic activity of monocytic MVs in these assays. Using tumor-implanted mice and ob/ob mice as models, we revealed that miR-150 secretion, which is increased for diseases such as cancers and diabetes, significantly promotes angiogenesis. The delivery of anti-miR-150 antisense oligonucleotides into tumor-implanted mice and ob/ob mice via MVs, however, strongly reduced angiogenesis in both types of mice. Our results collectively demonstrate that secretion of miR-150 via MVs can promote angiogenesis in vitro and in vivo, and we also present a novel microRNA-based therapeutic approach for disease treatment. PMID:23766514

  3. Micro- and Nanopatterned Topographical Cues for Regulating Macrophage Cell Shape and Phenotype.

    PubMed

    Luu, Thuy U; Gott, Shannon C; Woo, Bryan W K; Rao, Masaru P; Liu, Wendy F

    2015-12-30

    Controlling the interactions between macrophages and biomaterials is critical for modulating the response to implants. While it has long been thought that biomaterial surface chemistry regulates the immune response, recent studies have suggested that material geometry may in fact dominate. Our previous work demonstrated that elongation of macrophages regulates their polarization toward a pro-healing phenotype. In this work, we elucidate how surface topology might be leveraged to alter macrophage cell morphology and polarization state. Using a deep etch technique, we fabricated titanium surfaces containing micro- and nanopatterned grooves, which have been previously shown to promote cell elongation. Morphology, phenotypic markers, and cytokine secretion of murine bone marrow derived macrophages on different groove widths were analyzed. The results suggest that micro- and nanopatterned grooves influenced macrophage elongation, which peaked on substrates with 400-500 nm wide grooves. Surface grooves did not affect inflammatory activation but drove macrophages toward an anti-inflammatory, pro-healing phenotype. While secretion of TNF-alpha remained low in macrophages across all conditions, macrophages secreted significantly higher levels of anti-inflammatory cytokine, IL-10, on intermediate groove widths compared to cells on other Ti surfaces. Our findings highlight the potential of using surface topography to regulate macrophage function, and thus control the wound healing and tissue repair response to biomaterials. PMID:26605491

  4. Micro checkerboard patterned polymeric surface with discrete rigidity for studying cell migration

    NASA Astrophysics Data System (ADS)

    Hong, Juhee; Lee, Sujin; Park, Sukho; Lee, Junghoon

    2015-04-01

    The control of cell migration has an important role in processes ranging from developmental morphogenesis to the pathogenesis. In this study, we describe a novel approach to develop a micro-checkerboard patterned polymeric flat surface with discrete surface stiffness. This platform as a culture substrate allows us to explore the mechanism of durotaxis, referred to as the directed cell movement via the gradient of surface stiffness. The flat surface with different rigidity was achieved in two stages of fabrication. First, polydimethylsiloxane (PDMS) was pressed and cured on a glass substrate with trenches of varying depths in a checkerboard arrangement, and then, a thin PDMS layer was spin coated on the previous pattern to make the flat surface. The stiff region is defined by a thin layer (2.5 µm) of PDMS and the soft region is defined by a thick one (7.5 µm). To investigate the migratory cell behavior, the NIH 3T3 cell was cultured. The result demonstrates that a single cell showed clearly a migratory cell behavior toward the stiffer regions driven by the difference of effective surface stiffness. At high cell density, the effect of cell migration on effective surface stiffness decreased with increasing cell-cell interactions. However, cell migration was still dominated by difference of effective surface stiffness while fluctuating at the boundary between the stiff and soft regions. This approach enables us to control the mechanical and topological properties of surface. The developed platform will also offer a useful tool to study cell-substrate interaction mediated by surface stiffness (e.g. mechanotransduction).

  5. Topographical effects on fiber-mediated microRNA delivery to control oligodendroglial precursor cells development.

    PubMed

    Diao, Hua Jia; Low, Wei Ching; Lu, Q Richard; Chew, Sing Yian

    2015-11-01

    Effective remyelination in the central nervous system (CNS) facilitates the reversal of disability in patients with demyelinating diseases such as multiple sclerosis. Unfortunately until now, effective strategies of controlling oligodendrocyte (OL) differentiation and maturation remain limited. It is well known that topographical and biochemical signals play crucial roles in modulating cell fate commitment. Therefore, in this study, we explored the combined effects of scaffold topography and sustained gene silencing on oligodendroglial precursor cell (OPC) development. Specifically, microRNAs (miRs) were incorporated onto electrospun polycaprolactone (PCL) fiber scaffolds with different fiber diameters and orientations. Regardless of fiber diameter and orientation, efficient knockdown of differentiation inhibitory factors were achieved by either topography alone (up to 70%) or fibers integrated with miR-219 and miR-338 (up to 80%, p < 0.05). Small fiber promoted OPC differentiation by inducing more RIP(+) cells (p < 0.05) while large fiber promoted OL maturation by inducing more MBP(+) cells (p < 0.05). Random fiber enhanced more RIP(+) cells than aligned fibers (p < 0.05), regardless of fiber diameter. Upon miR-219/miR-338 incorporation, 2 μm aligned fibers supported the most MBP(+) cells (∼17%). These findings indicated that the coupling of substrate topographic cues with efficient gene silencing by sustained microRNA delivery is a promising way for directing OPC maturation in neural tissue engineering and controlling remyelination in the CNS. PMID:26310106

  6. MicroRNA-146a modulates B-cell oncogenesis by regulating Egr1

    PubMed Central

    Contreras, Jorge R.; Palanichamy, Jayanth Kumar; Tran, Tiffany M.; Fernando, Thilini R.; Rodriguez-Malave, Norma I.; Goswami, Neha; Arboleda, Valerie A.; Casero, David; Rao, Dinesh S.

    2015-01-01

    miR-146a is a NF-κB induced microRNA that serves as a feedback regulator of this critical pathway. In mice, deficiency of miR-146a results in hematolymphoid cancer at advanced ages as a consequence of constitutive NF-κB activity. In this study, we queried whether the deficiency of miR-146a contributes to B-cell oncogenesis. Combining miR-146a deficiency with transgenic expression of c-Myc led to the development of highly aggressive B-cell malignancies. Mice transgenic for c-Myc and deficient for miR-146a were characterized by significantly shortened survival, increased lymph node involvement, differential involvement of the spleen and a mature B-cell phenotype. High-throughput sequencing of the tumors revealed significant dysregulation of approximately 250 genes. Amongst these, the transcription factor Egr1 was consistently upregulated in mice deficient for miR-146a. Interestingly, transcriptional targets of Egr1 were enriched in both the high-throughput dataset and in a larger set of miR-146a-deficient tumors. miR-146a overexpression led to downregulation of Egr1 and downstream targets with concomitant decrease in cell growth. Direct targeting of the human EGR1 by miR-146a was seen by luciferase assay. Together our findings illuminate a bona fide role for miR-146a in the modulation of B-cell oncogenesis and reveal the importance of understanding microRNA function in a cell- and disease-specific context. PMID:25906746

  7. Activated mineralocorticoid receptor regulates micro-RNA-29b in vascular smooth muscle cells.

    PubMed

    Bretschneider, Maria; Busch, Bianca; Mueller, Daniel; Nolze, Alexander; Schreier, Barbara; Gekle, Michael; Grossmann, Claudia

    2016-04-01

    Inappropriately activated mineralocorticoid receptor (MR) is a risk factor for vascular remodeling with unclear molecular mechanism. Recent findings suggest that post-transcriptional regulation by micro-RNAs (miRs) may be involved. Our aim was to search for MR-dependent miRs in vascular smooth muscle cells (VSMCs) and to explore the underlying molecular mechanism and the pathologic relevance. We detected that aldosteroneviathe MR reduces miR-29bin vivoin murine aorta and in human primary and cultured VSMCs (ED50= 0.07 nM) but not in endothelial cells [quantitative PCR (qPCR), luciferase assays]. This effect was mediated by an increased decay of miR-29b in the cytoplasm with unchanged miR-29 family member or primary-miR levels. Decreased miR-29b led to an increase in extracellular matrix measured by ELISA and qPCR and enhanced VSMC migration in single cell-tracking experiments. Additionally, cell proliferation and the apoptosis/necrosis ratio (caspase/lactate dehydrogenase assay) was modulated by miR-29b. Enhanced VSMC migration by aldosterone required miR-29b regulation. Control experiments were performed with scrambled RNA and empty plasmids, by comparing aldosterone-stimulated with vehicle-incubated cells. Overall, our findings provide novel insights into the molecular mechanism of aldosterone-mediated vascular pathogenesis by identifying miR-29b as a pathophysiologic relevant target of activated MR in VSMCs and by highlighting the importance of miR processing for miR regulation.-Bretschneider, M., Busch, B., Mueller, D., Nolze, A., Schreier, B., Gekle, M., Grossmann, C. Activated mineralocorticoid receptor regulates micro-RNA-29b in vascular smooth muscle cells. PMID:26728178

  8. MicroRNA-26a regulates glucose metabolism by direct targeting PDHX in colorectal cancer cells

    PubMed Central

    2014-01-01

    Background Reprogramming energy metabolism has been an emerging hallmark of cancer cells. MicroRNAs play important roles in glucose metabolism. Methods The targets of microRNA-26a (miR-26a) were predicted by bioinformatics tools. The efficacy of miR-26a binding the 3′-untranslated region (UTR) of pyruvate dehydrogenase protein X component (PDHX) mRNA was evaluated using a dual-luciferase reporter assay. The PDHX expression at the mRNA and protein level in several colon cancer cell lines was quantified with real-time PCR and Western blot analysis respectively. The effects of miR-26a on glucose metabolism were determined by detecting the content of glucose consumption, production of lactate, pyruvate, and acetyl-coenzyme A. Results The expression of miR-26a is inversely associated with the level of its targeting protein PDHX in several colon cancer cell lines with different malignancy potentials. MiR-26a inhibits PDHX expression by direct targeting the 3′-UTR of PDHX mRNA. The glucose consumption and lactate concentration were both greatly increased in colon cancer cells than the normal colon mucosal epithelia under physiological conditions. The overexpression of miR-26a in HCT116 cells efficiently improved the accumulation of pyruvate and decreased the production of acetyl coenzyme A. Meanwhile the inhibition of miR-26a expression induced inverse biological effects. Conclusions MiR-26a regulates glucose metabolism of colorectal cancer cells by direct targeting the PDHX, which inhibits the conversion of pyruvate to acetyl coenzyme A in the citric acid cycle. PMID:24935220

  9. Long-term climbing fibre activity induces transcription of microRNAs in cerebellar Purkinje cells.

    PubMed

    Barmack, Neal H; Qian, Zuyuan; Yakhnitsa, Vadim

    2014-09-26

    Synaptic activation of central neurons is often evoked by electrical stimulation leading to post-tetanic potentiation, long-term potentiation or long-term depression. Even a brief electrical tetanus can induce changes in as many as 100 proteins. Since climbing fibre activity is often associated with cerebellar behavioural plasticity, we used horizontal optokinetic stimulation (HOKS) to naturally increase synaptic input to floccular Purkinje cells in mice for hours, not minutes, and investigated how this activity influenced the transcription of microRNAs, small non-coding nucleotides that reduce transcripts of multiple, complementary mRNAs. A single microRNA can reduce the translation of as many as 30 proteins. HOKS evoked increases in 12 microRNA transcripts in floccular Purkinje cells. One of these microRNAs, miR335, increased 18-fold after 24 h of HOKS. After HOKS stopped, miR335 transcripts decayed with a time constant of approximately 2.5 h. HOKS evoked a 28-fold increase in pri-miR335 transcripts compared with an 18-fold increase in mature miR335 transcripts, confirming that climbing fibre-evoked increases in miR335 could be attributed to increases in transcription. We used three screens to identify potential mRNA targets for miR335 transcripts: (i) nucleotide complementarity, (ii) detection of increased mRNAs following microinjection of miR335 inhibitors into the cerebellum, and (iii) detection of decreased mRNAs following HOKS. Two genes, calbindin and 14-3-3-θ, passed these screens. Transfection of N2a cells with miR335 inhibitors or precursors inversely regulated 14-3-3-θ transcripts. Immunoprecipitation of 14-3-3-θ co-immunoprecipitated PKC-γ and GABAAγ2. Knockdown of either 14-3-3-θ or PKC-γ decreased the serine phosphorylation of GABAAγ2, suggesting that 14-3-3-θ and PKC-γ under the control of miR335 homeostatically regulate the phosphorylation and insertion of GABAAγ2 into the Purkinje cell post-synaptic membrane. PMID:25135969

  10. MicroRNA-383 expression regulates proliferation, migration, invasion, and apoptosis in human glioma cells.

    PubMed

    Xu, Dawei; Ma, Pengju; Gao, Guojun; Gui, Yongkun; Niu, Xiaolu; Jin, Baozhe

    2015-09-01

    This study aims to evaluate microRNA-383 (miR-383) expression level in glioma cells and its influences on proliferation, migration, invasion, apoptosis, and cell cycle in glioma cells. miR-383 expression levels were determined by real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR). Thirty BALB/c-nu mice were randomly assigned into three groups: U87-miR-383 group, vector-control group, and blank group. Tumorigenicity experiment was conducted to confirm the function of miR-383. U251 and U87 glioma cells were divided into three groups: non-transfected control cells (NT group), glioma cells transfected with miR-383 (miR-383 group), and glioma cells transfected with negative sequence (NC group). Transfection efficiency was measured by qRT-PCR. Cell counting kit-8 (CCK-8) assay was used to detect cell proliferation. Cell migration and invasion were examined by utilizing a Transwell chamber. Cell cycle and apoptosis were analyzed by flow cytometry. The qRT-PCR results revealed that miR-383 expression was down-regulated in human glioma cells, and was negatively related to the pathological grading of glioma. The rates of tumor growth in vector-control group and blank group were significantly faster than that in U87-miR-383 group, and the average tumor volume and weight in vector-control group and blank group were increased as compared with U87-miR-383 group. Additionally, miR-383 levels in miR-383 group were higher than those in NT group and NC group. CCK-8 assay indicated lower cell viability in miR-383 group as compared with NT group and NC group. Flow cytometry implied that the percentages of cells in miR-383 group reduced, while the cell apoptosis rate enhanced compared with NT group and NC group. In conclusion, our findings suggest that miR-383 expression is down-regulated in glioma cells, inhibiting cell proliferation, migration, and invasion, affecting the cell cycle, and inducing cell apoptosis. PMID:25936342

  11. microRNA-155 Regulates the Generation of Immunoglobulin Class-Switched Plasma Cells

    PubMed Central

    Vigorito, Elena; Perks, Kerry L; Abreu-Goodger, Cei; Bunting, Sam; Xiang, Zou; Kohlhaas, Susan; Das, Partha P.; Miska, Eric A.; Rodriguez, Antony; Bradley, Allan; Smith, Kenneth G. C.; Rada, Cristina; Enright, Anton J.; Toellner, Kai-Michael; MacLennan, Ian C.M.; Turner, Martin

    2014-01-01

    Summary MicroRNA-155 (miR-155) is expressed by cells of the immune system following activation and has been shown to be required for antibody production following vaccination with attenuated Salmonella. Here we show the intrinsic requirement for miR-155 in B cell responses to thymus-dependent and independent antigens. B cells lacking miR-155 generated reduced extra-follicular and germinal center responses and failed to produce high affinity IgG1 antibodies. Gene expression profiling of activated B cells indicated that miR-155 regulates an array of genes with diverse function-many of which are predicted targets of miR-155. The transcription factor Pu.1 is validated as a direct target of miR155 mediated inhibition. When Pu.1 is over-expressed in wild type B cells fewer IgG1 cells are produced, indicating that loss of Pu.1 regulation is a contributing factor to the miR-155 deficient phenotype. Our results implicate post-transcriptional regulation of gene expression for establishing the terminal differentiation program of B cells. PMID:18055230

  12. MicroRNA-455 suppresses non-small cell lung cancer through targeting ZEB1.

    PubMed

    Li, Ying-Jie; Ping, Chen; Tang, Jian; Zhang, Wen

    2016-06-01

    MicroRNA-455 (miRNA-455), which is downregulated in human cancer, potently mediates the multiple steps of carcinogenesis. However, the role of miR-455 in non-small cell lung cancer (NSCLC) carcinogenesis remains unclear. In present study, we determined the mature miRNA-455 expression in NSCLC tissues and cells by real-time PCR. Follow-up studies examined the effects of a miR-455 mimic (gain of function) on cell proliferation, migration, and invasion. Our data indicate that miR-455 was significantly down-regulated in NSCLC cell lines and tissues. In functional assays, overexpression of miR-455 suppressed the proliferation, migration, and invasion of NSCLC cell lines. Data from reporter assays showed that miR-455 directly binds to 3'UTR of ZEB1 and suppresses the endogenous level of ZEB1 protein expression. Furthermore, overexpression of ZEB1 reverses miR-455-suppressed malignant phenotype of NSCLC cells. Moreover, we found that upregulation of ZEB1 expression is inversely associated with miR-455 expression in NSCLC tissues. Taken together, miR-455 as an anti-oncogene in non-small cell lung cancer through up-regulation of ZEB1 and serve as a potential therapeutic target in NSCLC. PMID:26801503

  13. A micro-Raman spectroscopic investigation of leukemic U-937 cells in aged cultures

    NASA Astrophysics Data System (ADS)

    Fazio, Enza; Trusso, Sebastiano; Franco, Domenico; Nicolò, Marco Sebastiano; Allegra, Alessandro; Neri, Fortunato; Musolino, Caterina; Guglielmino, Salvatore P. P.

    2016-04-01

    Recently it has been shown that micro-Raman spectroscopy combined with multivariate analysis is able to discriminate among different types of tissues and tumoral cells by the detection of significant alterations and/or reorganizations of complex biological molecules, such as nucleic acids, lipids and proteins. Moreover, its use, being in principle a non-invasive technique, appears an interesting clinical tool for the evaluation of the therapeutical effects and of the disease progression. In this work we analyzed molecular changes in aged cultures of leukemia model U937 cells with respect to fresh cultures of the same cell line. In fact, structural variations of individual neoplastic cells on aging may lead to a heterogeneous data set, therefore falsifying confidence intervals, increasing error levels of analysis and consequently limiting the use of Raman spectroscopy analysis. We found that the observed morphological changes of U937 cells corresponded to well defined modifications of the Raman contributions in selected spectral regions, where markers of specific functional groups, useful to characterize the cell state, are present. A detailed subcellular analysis showed a change in cellular organization as a function of time, and correlated to a significant increase of apoptosis levels. Besides the aforementioned study, Raman spectra were used as input for principal component analysis (PCA) in order to detect and classify spectral changes among U937 cells.

  14. Paper-based membraneless hydrogen peroxide fuel cell prepared by micro-fabrication

    NASA Astrophysics Data System (ADS)

    Mousavi Ehteshami, Seyyed Mohsen; Asadnia, Mohsen; Tan, Swee Ngin; Chan, Siew Hwa

    2016-01-01

    A paper-based membraneless single-compartment hydrogen peroxide power source prepared by micro-electromechanical systems (MEMS) technology is reported. The cell utilizes hydrogen peroxide as both fuel and oxidant in a low volume cell fabricated on paper. The fabrication method used is a simple method where precise, small-sized patterns are produced which include the hydrophilic paper bounded by hydrophobic resin. Open circuit potentials of 0.61 V and 0.32 V are achieved for the cells fabricated with Prussian Blue as the cathode and aluminium/nickel as the anode materials, respectively. The power produced by the cells is 0.81 mW cm-2 at 0.26 V and 0.38 mW cm-2 at 0.14 V, respectively, even after the cell is bent or distorted. Such a fuel cell provides an easily fabricated, environmentally friendly, flexible and cost saving power source. The cell may be integrated within a self-sustained diagnostic system to provide the on-demand power for future bio-sensing applications.

  15. MicroRNA-155 promotes autoimmune inflammation by enhancing inflammatory T cell development.

    PubMed

    O'Connell, Ryan M; Kahn, Daniel; Gibson, William S J; Round, June L; Scholz, Rebecca L; Chaudhuri, Aadel A; Kahn, Melissa E; Rao, Dinesh S; Baltimore, David

    2010-10-29

    Mammalian noncoding microRNAs (miRNAs) are a class of gene regulators that have been linked to immune system function. Here, we have investigated the role of miR-155 during an autoimmune inflammatory disease. Consistent with a positive role for miR-155 in mediating inflammatory responses, Mir155(-/-) mice were highly resistant to experimental autoimmune encephalomyelitis (EAE). miR-155 functions in the hematopoietic compartment to promote the development of inflammatory T cells including the T helper 17 (Th17) cell and Th1 cell subsets. Furthermore, the major contribution of miR-155 to EAE was CD4(+) T cell intrinsic, whereas miR-155 was also required for optimum dendritic cell production of cytokines that promoted Th17 cell formation. Our study shows that one aspect of miR-155 function is the promotion of T cell-dependent tissue inflammation, suggesting that miR-155 might be a promising therapeutic target for the treatment of autoimmune disorders. PMID:20888269

  16. Bisphenol A Exposure Leads to Specific MicroRNA Alterations in Placental Cells

    PubMed Central

    Avissar-Whiting, Michele; Veiga, Keila; Uhl, Kristen; Maccani, Matthew; Gagne, Luc; Moen, Erika; Marsit, Carmen J.

    2010-01-01

    Exposure to bisphenol-A (BPA) has been observed to alter developmental pathways and cell processes, at least in part, through epigenetic mechanisms. This study sought to investigate the effect of BPA on microRNAs (miRNAs) in human placental cells. miRNA microarray was performed following BPA treatment in three immortalized cytotrophoblast cell lines and the results validated using quantitative real-time PCR. For functional analysis, overexpression constructs were stably transfected into cells that were then assayed for changes in proliferation and response to toxicants. Microarray analysis revealed several miRNAs to be significantly altered in response to BPA treatment in two cell lines. Real-time PCR results confirmed that miR-146a was particularly strongly induced and its overexpression in cells led to slower proliferation as well as higher sensitivity to the DNA damaging agent, bleomycin. Overall, these results suggest that BPA can alter miRNA expression in placental cells, a potentially novel mode of BPA toxicity. PMID:20417706

  17. Controlling mesenchymal stem cells differentiate into contractile smooth muscle cells on a TiO2 micro/nano interface: Towards benign pericytes environment for endothelialization.

    PubMed

    Li, Jingan; Qin, Wei; Zhang, Kun; Wu, Feng; Yang, Ping; He, Zikun; Zhao, Ansha; Huang, Nan

    2016-09-01

    Building healthy and oriented smooth muscle cells (SMCs) environment is an effective method for improving the surface endothelialization of the cardiovascular implants. However, a long-term and stable source of SMCs for implantation without immune rejection and inflammation has not been solved, and mesenchymal stem cells (MSCs) differentiation may be a good choice. In this work, two types of TiO2 micro/nano interfaces were fabricated on titanium surface by photolithography and anodic oxidation. These TiO2 micro/nano interfaces were used to regulate the differentiation of the MSCs. The X-ray diffraction (XRD) detection showed that the TiO2 micro/nano interfaces possessed the anatase crystal structure, suggesting good cytocompatibility. The CCK-8 results indicated the TiO2 micro/nano interfaces improved MSC proliferation, further immunofluorescence staining and calculation of the cell morphology index proved the micro/nano surfaces also elongated MSCs and regulated MSCs oriented growth. The specific staining of α-SMA, CNN-1, vWF, CD44 and CD133 markers revealed that the micro/nano surfaces induced MSCs differentiation to contractile SMCs, and the endothelial cells (ECs) culture experiment indicated that the MSCs induced by micro/nano interfaces contributed to the ECs attachment and proliferation. This method will be further studied and applied for the surface modification of the cardiovascular implants. PMID:27232304

  18. Laser-induced vapor nanobubbles for efficient delivery of macromolecules in live cells

    NASA Astrophysics Data System (ADS)

    Xiong, Ranhua; Raemdonck, Koen; Peynshaert, Karen; Lentacker, Ine; De Cock, Ine; Demeester, Jo; De Smedt, Stefaan C.; Skirtach, Andre G.; Braeckmans, Kevin

    2015-03-01

    Macromolecular agents such as nucleic acids and proteins need to be delivered into living cells for therapeutic purposes. Among physical methods to deliver macromolecules across the cell membrane, laser-induced photoporation using plasmonic nanoparticles is a method that is receiving increasing attention in recent years. By irradiating gold nanoparticles bound to the cell membrane with laser light, nanosized membrane pores can be created. Pores are formed by localized heating or by vapour nanobubbles (VNBs) depending on the incident laser energy. Macromolecules in the surrounding cell medium can then diffuse through the transiently formed pores into the cytoplasm. While both heating and VNBs have been reported before for permeabilization of the cell membrane, it remains unclear which of both methods is more efficient in terms of cell loading with minimal cytotoxicity. In this study we report that under condition of a single 7 ns laser pulse VNBs are substantially more efficient for the cytosolic delivery of macromolecules. We conclude that VNB formation is an interesting photoporation mechanism for fast and efficient macromolecular delivery in live cells.

  19. Electrolyte vapor condenser

    DOEpatents

    Sederquist, Richard A.; Szydlowski, Donald F.; Sawyer, Richard D.

    1983-01-01

    A system is disclosed for removing electrolyte from a fuel cell gas stream. The gas stream containing electrolyte vapor is supercooled utilizing conventional heat exchangers and the thus supercooled gas stream is passed over high surface area passive condensers. The condensed electrolyte is then drained from the condenser and the remainder of the gas stream passed on. The system is particularly useful for electrolytes such as phosphoric acid and molten carbonate, but can be used for other electrolyte cells and simple vapor separation as well.

  20. Electrolyte vapor condenser

    DOEpatents

    Sederquist, R.A.; Szydlowski, D.F.; Sawyer, R.D.

    1983-02-08

    A system is disclosed for removing electrolyte from a fuel cell gas stream. The gas stream containing electrolyte vapor is supercooled utilizing conventional heat exchangers and the thus supercooled gas stream is passed over high surface area passive condensers. The condensed electrolyte is then drained from the condenser and the remainder of the gas stream passed on. The system is particularly useful for electrolytes such as phosphoric acid and molten carbonate, but can be used for other electrolyte cells and simple vapor separation as well. 3 figs.

  1. Development of high-bandgap AlGaInP solar cells grown by organometallic vapor-phase epitaxy

    DOE PAGESBeta

    Perl, Emmett E.; Simon, John; Geisz, John F.; Olavarria, Waldo; Young, Michelle; Duda, Anna; Friedman, Daniel J.; Steiner, Myles A.

    2016-03-29

    AlGaInP solar cells with bandgaps between 1.9 and 2.2 eV are investigated for use in next-generation multijunction photovoltaic devices. This quaternary alloy is of great importance to the development of III-V solar cells with five or more junctions and for cells optimized for operation at elevated temperatures because of the high bandgaps required in these designs. In this work, we explore the conditions for the organometallic vapor-phase epitaxy growth of AlGaInP and study their effects on cell performance. Initial efforts focused on developing ~2.0-eV AlGaInP solar cells with a nominal aluminum composition of 12%. Under the direct spectrum at 1000more » W/m2 (AM1.5D), the best of these samples had an open-circuit voltage of 1.59 V, a bandgap-voltage offset of 440 mV, a fill factor of 88.0%, and an efficiency of 14.8%. We then varied the aluminum composition of the alloy from 0% to 24% and were able to tune the bandgap of the AlGaInP layers from ~1.9 to ~2.2 eV. Furthermore, while the samples with a higher aluminum composition exhibited a reduced quantum efficiency and increased bandgap-voltage offset, the bandgap-voltage offset remained at 500 mV or less, up to a bandgap of ~2.1 eV.« less

  2. microRNA-153 Targets mTORC2 Component Rictor to Inhibit Glioma Cells

    PubMed Central

    Cui, Yan; Zhao, Jizong; Yi, Lei; Jiang, Yugang

    2016-01-01

    Rictor upregulation and mTORC complex 2 (mTORC2) over-activation participate in glioma cell progression, yet the underling mechanisms are not known. We here identified microRNA-153 (miR-153) as a potential anti-Rictor miRNA, which was downregulated in multiple human glioma tissues and glioma cell lines (U87MG, T98G, U373MG and U251MG). miR-153 downregulation was correlated with Rictor (mRNA and protein) upregulation and p-Akt Ser473 (the mTORC2 indicator) over-activation in the glioma tissues and cells. Our in vitro evidences suggested that Rictor could be one primary target of miR-153 in glioma cells. Exogenous overexpression of miR-153 downregulated Rictor (mRNA and protein) and decreased p-Akt Ser473 in U87MG cells, leading to significant growth inhibition and apoptosis activation. Notably, U87MG cells with Rictor shRNA knockdown showed similar phenotypes of cells with miR-153 overexpression. More importantly, in Rictor-silenced U87MG cells, miR-153 expression failed to further affect cell growth nor apoptosis. In vivo, we showed that miR-153 overexpression dramatically inhibited U87MG tumor growth in nude mice. Together, these results suggest that miR-153 downregulation could be one important reason of Rictor upregulation and mTORC2 over-activation in glioma cells. Further, miR-153-induced anti-glioma cell activity is possibly via downregulating Rictor. PMID:27295037

  3. GaAs Solar Cells Grown by Hydride Vapor-Phase Epitaxy and the Development of GaInP Cladding Layers

    SciTech Connect

    Simon, John; Schulte, Kevin L.; Young, David L.; Haegel, Nancy M.; Ptak, Aaron J.

    2016-01-01

    The high cost of high-efficiency III-V photovoltaic devices currently limits them to niche markets. Hydride vapor-phase epitaxy (HVPE) growth of III-V materials recently reemerged as a low-cost, high-throughput alternative to conventional metal- organic vapor-phase epitaxy (MOVPE) growth of high-efficiency solar cells. Previously, we demonstrated unpassivated HVPEgrown GaAs p-n junctions with good quantum efficiency and high open-circuit voltage (Voc). In this work, we demonstrate the growth of GaInPby HVPE for use as a high-quality surface passivation layer to GaAs solar cells. Solar cells grown with GaInP window layers show significantly improved quantum efficiency compared with unpassivated cells, increasing the short-circuit current (JSC) of these low-cost devices. These results show the potential of low-cost HVPE for the growth of high-quality III-V devices.

  4. Data on cell spread area and directional contraction in human umbilical vein endothelial cells on fibronectin and on collagen type I-coated micro-posts

    PubMed Central

    Han, Jing-Jing; Tan, Hui-Foon; Feng, Chen; Wee, Wei-Kiat; Tee, Shang-You; Tan, Suet-Mien

    2016-01-01

    Fibronectin and collagen type I are abundant extracellular matrix proteins that modulate cell mechanics and they regulate angiogenic sprouting. In this data article, fibronectin- or collagen type I-coated micro-posts were used to examine the traction force, cell spread area and directional contraction of human umbilical vein endothelial cells (HUVECs). PMID:26937451

  5. MicroRNAs Associated with the Efficacy of Photodynamic Therapy in Biliary Tract Cancer Cell Lines

    PubMed Central

    Wagner, Andrej; Mayr, Christian; Bach, Doris; Illig, Romana; Plaetzer, Kristjan; Berr, Frieder; Pichler, Martin; Neureiter, Daniel; Kiesslich, Tobias

    2014-01-01

    Photodynamic therapy (PDT) is a palliative treatment option for unresectable hilar biliary tract cancer (BTC) showing a considerable benefit for survival and quality of life with few side effects. Currently, factors determining the cellular response of BTC cells towards PDT are unknown. Due to their multifaceted nature, microRNAs (miRs) are a promising analyte to investigate the cellular mechanisms following PDT. For two photosensitizers, Photofrin® and Foscan®, the phototoxicity was investigated in eight BTC cell lines. Each cell line (untreated) was profiled for expression of n = 754 miRs using TaqMan® Array Human MicroRNA Cards. Statistical analysis and bioinformatic tools were used to identify miRs associated with PDT efficiency and their putative targets, respectively. Twenty miRs correlated significantly with either high or low PDT efficiency. PDT was particularly effective in cells with high levels of clustered miRs 25-93*-106b and (in case of miR-106b) a phenotype characterized by high expression of the mesenchymal marker vimentin and high proliferation (cyclinD1 and Ki67 expression). Insensitivity towards PDT was associated with high miR-200 family expression and (for miR-cluster 200a/b-429) expression of differentiation markers Ck19 and Ck8/18. Predicted and validated downstream targets indicate plausible involvement of miRs 20a*, 25, 93*, 130a, 141, 200a, 200c and 203 in response mechanisms to PDT, suggesting that targeting these miRs could improve susceptibility to PDT in insensitive cell lines. Taken together, the miRNome pattern may provide a novel tool for predicting the efficiency of PDT and—following appropriate functional verification—may subsequently allow for optimization of the PDT protocol. PMID:25380521

  6. Characterization of Combinatorial Effects of Toxic Substances by Cell Cultivation in Micro Segmented Flow

    NASA Astrophysics Data System (ADS)

    Cao, J.; Kürsten, D.; Funfak, A.; Schneider, S.; Köhler, J. M.

    This chapter reviews the application of micro segmented flow for the screening of toxic effects on bacteria, eukaryotic microorganisms, human cells and multicellular systems. Besides, the determination of complete dose/response functions of toxic substances with a minimum of cells and chemicals, it is reviewed how two- and multi-dimensional concentration spaces can be screened in order to evaluate combinatorial effects of chemicals on cells. The challenge for the development of new and miniaturized methods is derived from the increase of the number of different used substances in technique, agriculture and medicine, from the increasing release of new substances and nanomaterials into our environment and from the improvement of the insight of toxicity of natural substances and the interferences between different substances resulting in toxic effects on different organisms, cells and tissues. The application of two-dimensional toxicological screenings on selected examples of effector combinations is described. Examples for the detection of an independent, an additive and a synergistic interference between two substances are given. In addition, it is shown that the screening for toxicological effects in complete two-dimensional concentration spaces allows the detection of complex response behaviour—for example, the formation of tolerances and stimulation peaks—which thereby can be characterized. The characterization of interference of toxic organic substances with silver nanoparticles is reported as an example for the potential of micro segmented-flow technique for evaluating the toxicological impact of new materials. Finally, it is demonstrated that the technique can be applied for different organisms like simple bacteria, single cell alga such as Chlorella vulgaris and multicellular systems up to the development of complete organisms beginning from eggs.

  7. 17.6%-Efficient radial junction solar cells using silicon nano/micro hybrid structures

    NASA Astrophysics Data System (ADS)

    Lee, Kangmin; Hwang, Inchan; Kim, Namwoo; Choi, Deokjae; Um, Han-Don; Kim, Seungchul; Seo, Kwanyong

    2016-07-01

    We developed a unique nano- and microwire hybrid structure by selectively modifying only the tops of microwires using metal-assisted chemical etching. The proposed nano/micro hybrid structure not only minimizes surface recombination but also absorbs 97% of incident light under AM 1.5G illumination, demonstrating outstanding light absorption compared to that of planar (59%) and microwire arrays (85%). The proposed hybrid solar cells with an area of 1 cm2 exhibit power conversion efficiencies (Eff) of up to 17.6% under AM 1.5G illumination. In particular, the solar cells show a high short-circuit current density (Jsc) of 39.5 mA cm-2 because of the high light-absorbing characteristics of the nanostructures. This corresponds to an approximately 61.5% and 16.5% increase in efficiency compared to that of a planar silicon solar cell (Eff = 10.9%) and a microwire solar cell (Eff = 15.1%), respectively. Therefore, we expect the proposed hybrid structure to become a foundational technology for the development of highly efficient radial junction solar cells.We developed a unique nano- and microwire hybrid structure by selectively modifying only the tops of microwires using metal-assisted chemical etching. The proposed nano/micro hybrid structure not only minimizes surface recombination but also absorbs 97% of incident light under AM 1.5G illumination, demonstrating outstanding light absorption compared to that of planar (59%) and microwire arrays (85%). The proposed hybrid solar cells with an area of 1 cm2 exhibit power conversion efficiencies (Eff) of up to 17.6% under AM 1.5G illumination. In particular, the solar cells show a high short-circuit current density (Jsc) of 39.5 mA cm-2 because of the high light-absorbing characteristics of the nanostructures. This corresponds to an approximately 61.5% and 16.5% increase in efficiency compared to that of a planar silicon solar cell (Eff = 10.9%) and a microwire solar cell (Eff = 15.1%), respectively. Therefore, we expect the

  8. MicroRNA-26a is a novel regulator of vascular smooth muscle cell function.

    PubMed

    Leeper, Nicholas J; Raiesdana, Azad; Kojima, Yoko; Chun, Hyung J; Azuma, Junya; Maegdefessel, Lars; Kundu, Ramendra K; Quertermous, Thomas; Tsao, Philip S; Spin, Joshua M

    2011-04-01

    Aberrant smooth muscle cell (SMC) plasticity has been implicated in a variety of vascular disorders including atherosclerosis, restenosis, and abdominal aortic aneurysm (AAA) formation. While the pathways governing this process remain unclear, epigenetic regulation by specific microRNAs (miRNAs) has been demonstrated in SMCs. We hypothesized that additional miRNAs might play an important role in determining vascular SMC phenotype. Microarray analysis of miRNAs was performed on human aortic SMCs undergoing phenotypic switching in response to serum withdrawal, and identified 31 significantly regulated entities. We chose the highly conserved candidate miRNA-26a for additional studies. Inhibition of miRNA-26a accelerated SMC differentiation, and also promoted apoptosis, while inhibiting proliferation and migration. Overexpression of miRNA-26a blunted differentiation. As a potential mechanism, we investigated whether miRNA-26a influences TGF-β-pathway signaling. Dual-luciferase reporter assays demonstrated enhanced SMAD signaling with miRNA-26a inhibition, and the opposite effect with miRNA-26a overexpression in transfected human cells. Furthermore, inhibition of miRNA-26a increased gene expression of SMAD-1 and SMAD-4, while overexpression inhibited SMAD-1. MicroRNA-26a was also found to be downregulated in two mouse models of AAA formation (2.5- to 3.8-fold decrease, P < 0.02) in which enhanced switching from contractile to synthetic phenotype occurs. In summary, miRNA-26a promotes vascular SMC proliferation while inhibiting cellular differentiation and apoptosis, and alters TGF-β pathway signaling. MicroRNA-26a represents an important new regulator of SMC biology and a potential therapeutic target in AAA disease. PMID:20857419

  9. Mature microRNAs identified in highly purified nuclei from HCT116 colon cancer cells

    PubMed Central

    Park, Chang Won; Zeng, Yan; Zhang, Xiaoxiao; Subramanian, Subbaya

    2010-01-01

    MicroRNAs (miRNAs) have emerged as one of the major regulatory mechanisms of gene expression. A major function of miRNAs involves the post-transcriptional regulation of target mRNAs, which is reported to occur primarily in the cytoplasm. However, there is a significant amount of evidence demonstrating the existence of small non-coding RNAs, including small-interfering RNA (siRNA), miRNA and Piwi-interacting RNA (piRNA) in the nucleus. In order to elucidate the potential subcellular localizations and functions of miRNAs, we have identified numerous miRNAs that are present in isolated nuclei from human colon cancer HCT116 cells. MicroRNA profiles were compared between cytoplasmic and nuclear fractions of the HCT116 cell line on the basis of multiple microarray analyses. MicroRNA species showing significant existence in isolated and highly purified populations of nuclei were selected and further tested with RT-PCR. The nuclear localization of the mature form of miRNAs was verified again by control RT-PCR excluding the detection of premature forms of miRNA, such as pri-miRNA or pre-miRNA. The elevated levels of representative miRNAs identified in purified nuclei were confirmed by northern blot analysis, supporting the notion that significant numbers of mature miRNAs exist not only in the cytoplasm but also in the nucleus. These results will likely provide a basis for further studies concerning the intracellular trafficking and nuclear location of miRNAs. PMID:20864815

  10. Micro-channels in the mastoid anatomy. Indications of a separate blood supply of the air cell system mucosa by micro-CT scanning.

    PubMed

    Cros, Olivier; Borga, Magnus; Pauwels, Elin; Dirckx, Joris J J; Gaihede, Michael

    2013-07-01

    The mastoid air cell system has traditionally been considered to have a passive role in gas exchange and pressure regulation of the middle ear possibly with some acoustic function. However, more evidence has focused on the mucosa of the mastoid, which may play a more active role in regulation of middle ear pressure. In this study we have applied micro-CT scanning on a series of three human temporal bones. This approach greatly enhances the resolution (40-60 μm), so that we have discovered anatomical details, which has not been reported earlier. Thus, qualitative analysis using volume rendering has demonstrated notable micro-channels connecting the surface of the compact bone directly to the mastoid air cells as well as forming a network of connections between the air cells. Quantitative analysis on 2D slices was employed to determine the average diameter of these micro-channels (158 μm; range = 40-440 μm) as well as their density at a localized area (average = 75 cm(-2); range = 64-97 cm(-2)). These channels are hypothesized to contain a separate vascular supply for the mastoid mucosa. However, future studies of the histological structure of the micro-channels are warranted to confirm the hypothesis. Studies on the mastoid mucosa and its blood supply may improve our knowledge of its physiological properties, which may have important implications for our understanding of the pressure regulation of the middle ear. This article is part of a special issue entitled "MEMRO 2012". PMID:23518400

  11. Effects of hierarchical micro/nano-topographies on the morphology, proliferation and differentiation of osteoblast-like cells.

    PubMed

    Huang, Qianli; Elkhooly, Tarek A; Liu, Xujie; Zhang, Ranran; Yang, Xing; Shen, Zhijian; Feng, Qingling

    2016-09-01

    Coating the surfaces of titanium-based implants with appropriate hierarchical micro/nano-topographies resembling the structure of natural bone significantly enhances their biological performance. However, the relationship between nanostructures surfaces and their effects on modulating cellular response is not clearly understood. Moreover, it is not clear whether the surface chemistry or topography is the main factor on modulating cellular behavior, because the commonly used surface modification techniques for titanium-based implants simultaneously modify surface topography and chemistry. The aim of this study is to investigate osteoblast-like cell adhesion, proliferation and differentiation on hierarchical micro/nano-topographies with similar surface chemistry but different nano-scale features. Micro-arc oxidation and post hydrothermal treatment were employed to fabricate micro/nano-topographies on titanium. According to the morphological features, they were classified as microcrater (micro-topography), nanoplate (hierarchical topography with nanoplates) and nanoleaf (hierarchical topography with nanoleaves). The response of osteoblast like cells (SaOS-2) was studied on each surface after sputtering with a thin layer of gold (Au) to minimize the influence of surface chemistry. The morphological evaluation after histochemical staining revealed that the adherent cells were polygonal-shaped on microcrater surface, roundish on nanoplate surface and elongated on nanoleaf surface. Additionally, compared to microcrater surface, nanoplate surface slowed down cell proliferation and exhibited no enhancement on cell differentiation. However, nanoleaf surface supported cell proliferation and promoted cell differentiation. The results indicate that tuning morphological features of nanostructures on micro-topography can serve as a promising strategy to specifically modulate cellular response, such as cell morphology, proliferation, differentiation and mineralization. PMID

  12. Global microRNA expression is essential for murine mast cell development in vivo

    PubMed Central

    Oh, Sun Young; Brandal, Stephanie; Kapur, Reuben; Zhu, Zhou; Takemoto, Clifford M.

    2014-01-01

    microRNAs (miRNAs) are small, non-coding RNAs that have been shown to play a critical role in normal physiology and disease, such as hematopoietic development and cancer. However, their role in mast cell function and development is poorly understood. The major objective of this study was to determine how global miRNA expression affects mast cell physiology. The RNase III endonuclease, Dicer, is required for the processing of pre-miRNAs into mature miRNAs. To investigate the effect of global miRNA depletion on mast cells in vivo, we generated a mast cell-specific knock out of Dicer in mice. Transgenic mice (Mcpt5-Cre) that express Cre selectively in connective tissue mast cells were crossed with mice carrying the floxed conditional Dicer allele (Dicer fl/fl). Mcpt5-Cre x Dicer fl/fl mice with homozygous Dicer gene deletion in mast cells were found to have a profound mast cell deficiency with near complete loss of peritoneal, gastrointestinal, and skin mast cells. We examined the in vivo functional consequence of mast cell-specific Dicer deletion using an IgE-dependent passive systemic anaphylaxis (PSA) murine model. IgE sensitized wild type Mcpt5-Cre x Dicer +/+ and heterozygous Mcpt5-Cre x Dicer fl/+ mice show marked hypothermia with antigen; however, homozygous Mcpt5-Cre x Dicer fl/fl mice were completely unresponsive to antigen challenge. These studies suggest a critical role for Dicer and miRNA expression for establishment of tissue compartments of functional mast cells in vivo. PMID:25201754

  13. Profile of Exosomal and Intracellular microRNA in Gamma-Herpesvirus-Infected Lymphoma Cell Lines.

    PubMed

    Hoshina, Shiho; Sekizuka, Tsuyoshi; Kataoka, Michiyo; Hasegawa, Hideki; Hamada, Hiromichi; Kuroda, Makoto; Katano, Harutaka

    2016-01-01

    Exosomes are small vesicles released from cells, into which microRNAs (miRNA) are specifically sorted and accumulated. Two gamma-herpesviruses, Kaposi sarcoma-associated herpesvirus (KSHV) and Epstein-Barr virus (EBV), encode miRNAs in their genomes and express virus-encoded miRNAs in cells and exosomes. However, there is little information about the detailed distribution of virus-encoded miRNAs in cells and exosomes. In this study, we thus identified virus- and host-encoded miRNAs in exosomes released from KSHV- or EBV-infected lymphoma cell lines and compared them with intracellular miRNAs using a next-generation sequencer. Sequencing analysis demonstrated that 48% of the annotated miRNAs in the exosomes from KSHV-infected cells originated from KSHV. Human mir-10b-5p and mir-143-3p were much more highly concentrated in exosomes than in cells. Exosomes contained more nonexact mature miRNAs that did not exactly match those in miRBase than cells. Among the KSHV-encoded miRNAs, miRK12-3-5p was the most abundant exact mature miRNA in both cells and exosomes that exactly matched those in miRBase. Recently identified EXOmotifs, nucleotide motifs that control the loading of miRNAs into exosomes were frequently found within the sequences of KSHV-encoded miRNAs, and the presence of the EXOmotif CCCT or CCCG was associated with the localization of miRNA in exosomes in KSHV-infected cells. These observations suggest that specific virus-encoded miRNAs are sorted by EXOmotifs and accumulate in exosomes in virus-infected cells. PMID:27611973

  14. ALA-PDT of glioma cell micro-clusters in BD-IX rat brain

    NASA Astrophysics Data System (ADS)

    Madsen, Steen J.; Angell-Petersen, Even; Spetalen, Signe; Carper, Stephen W.; Ziegler, Sarah A.; Hirschberg, Henry

    2006-02-01

    A significant contributory factor to the poor prognosis of patients with glioblastoma multiforme is the inability of conventional treatments to eradicate infiltrating glioma cells. A syngeneic rat brain tumor model is used to investigate the effects of aminolevulinic acid (ALA)-mediated photodynamic therapy (PDT) on small clusters of tumor cells sequestered in normal brain. The intrinsic sensitivity of rat glioma cells to PDT was investigated by exposing ALA-incubated cells to a range of radiant exposures and irradiances using 635 nm light. Biodistribution studies were undertaken on tumor-bearing animals in order to determine the tumor selectivity of the photosensitizer following systemic administration (i.p.) of ALA. Effects of ALA-PDT on normal brain and gross tumor were evaluated using histopathology. Effects of PDT on isolated glioma cells in normal brain were investigated by treating animals 48 h after tumor cell implantation: a time when the micro-clusters of cells are protected by an intact blood-brain-barrier (BBB). Rat glioma cells in monolayer are susceptible to ALA-PDT - lower irradiances are more effective than higher ones. Fluorescence microscopy of frozen tissue sections showed that photosensitizer is produced with better than 200:1 tumor-to-normal tissue selectivity following i.p. ALA administration. ALA-PDT resulted in significant damage to both gross tumor and normal brain, however, the treatment failed to prolong survival of animals with newly implanted glioma cells compared to non-treated controls if the drug was delivered either i.p. or directly into the brain. In contrast, animals inoculated with tumor cells pre-incubated in vitro with ALA showed a significant survival advantage in response to PDT.

  15. DICER Inactivation Identifies Pancreatic β-Cell “Disallowed” Genes Targeted by MicroRNAs

    PubMed Central

    Martinez-Sanchez, Aida; Nguyen-Tu, Marie-Sophie

    2015-01-01

    Pancreatic β-cells are the body's sole source of circulating insulin and essential for the maintenance of blood glucose homeostasis. Levels of up to 66 “disallowed” genes, which are strongly expressed and play housekeeping roles in most other mammalian tissues, are unusually low in β-cells. The molecular mechanisms involved in repressing these genes are largely unknown. Here, we explore the role in gene disallowance of microRNAs (miRNAs), a type of small noncoding RNAs that silence gene expression at the posttranscriptional level and are essential for β-cell development and function. To selectively deplete miRNAs from adult β-cells, the miRNA-processing enzyme DICER was inactivated by deletion of the RNase III domain with a tamoxifen-inducible Pdx1CreER transgene. In this model, β-cell dysfunction was apparent 2 weeks after recombination and preceded a decrease in insulin content and loss of β-cell mass. Of the 14 disallowed genes studied, quantitative RT-quantitative real-time PCR revealed that 6 genes (Fcgrt, Igfbp4, Maf, Oat, Pdgfra, and Slc16a1) were up-regulated (1.4- to 2.1-fold, P < .05) at this early stage. Expression of luciferase constructs bearing the 3′-untranslated regions of the corresponding mRNAs in wild-type or DICER-null β-cells demonstrated that Fcgrt, Oat, and Pdgfra are miRNA direct targets. We thus reveal a role for miRNAs in the regulation of disallowed genes in β-cells and provide evidence for a novel means through which noncoding RNAs control the functional identity of these cells independently of actions on β-cell mass. PMID:26038943

  16. MicroRNA-383 Regulates the Apoptosis of Tumor Cells through Targeting Gadd45g

    PubMed Central

    Wu, Junyu; Wang, Daliang; Chen, Su; Yang, Xiaomei; Qian, Baohua

    2014-01-01

    Background MicroRNAs (miRNAs) are a class of small non-coding single-stranded RNA molecules that inhibit gene expression at post-transcriptional level. Gadd45g (growth arrest and DNA-damage-inducible 45 gamma) is a stress-response protein, which has been implicated in several biological processes, including DNA repair, the cell cycle and cell differentiation. Results In this work, we found that miR-383 is a negative regulator of Gadd45g. Forced expression of miR-383 decreased the expression of Gadd45g through binding to the 3′ untranslated region (3′-UTR), whereas inhibition of miR-383 increased Gadd45g expression. The presence of miR-383 increased the cellular sensitivity to DNA damage in breast cancer cells, which was rescued by ectopic expression of Gadd45g without the 3′-UTR. miR-383 also regulates the expression of Gadd45g in embryonic stem (ES) cells, but not their apoptosis under genotoxic stress. miR-383 was further showed to negatively regulate ES cell differentiation via targeting Gadd45g, which subsequently modulates the pluripotency-associated genes. Taken together, our study demonstrates that miR-383 is a negative regulator of Gadd45g in both tumor cells and ES cells, however, has distinct function in regulating cell apoptosis. miR-383 may be used as antineoplastic agents in cancer chemotherapy. Conclusion We demonstrate for the first time that miR-383 can specifically regulates the expression of Gadd45g by directly targeting to the 3-UTR region of Gadd45g mRNA, a regulatory process conserved in human tumor cells and mouse embryonic stem cells. These two compotents can be potentially used as antineoplastic agents in cancer chemotherapy. PMID:25415264

  17. Micro RNA-17-92 cluster mediates interleukin-4-suppressed IL-10 expression in B cells

    PubMed Central

    Liu, Zhi-Qiang; Yang, Gui; Geng, Xiao-Rui; Liu, Jiang-Qi; Mo, Li-Hua; Liu, Zhi-Gang; Yang, Ping-Chang

    2016-01-01

    The pathogenesis of allergen-related inflammation in the intestine is to be further understood. Micro RNA (miR) can regulate immune responses. This study aims to investigate the role of miR-17-92 cluster in the induction of food allergen-related inflammation in the intestine. In this study, a mouse model of food allergen-related intestinal inflammation was developed. Expression of miR-17-92 cluster in B cells of the intestinal mucosa was analyzed by real time quantitative RT-PCR. The results showed that the levels of miR-19a, one of the members of the miR-17-92 cluster, were detected in the B cells of the intestine of mice sensitized to ovalbumin, which was significantly higher than that in naïve control mice. The expression of IL-10 by B cells was significantly lower in the sensitized mice as compared with naive control mice. Exposure to IL-4 in the culture increased the expression of miR-19a as well as suppression the expression of IL-10 in B cells via remolding DNA structure at the IL-10 promoter locus. We conclude that B cells from sensitized mice show higher levels of miR-19a, which plays an important role in the suppression of IL-10 in the B cells. PMID:27347339

  18. Overexpression of microRNAs enhances recombinant protein production in Chinese hamster ovary cells.

    PubMed

    Loh, Wan Ping; Loo, Bernard; Zhou, Lihan; Zhang, Peiqing; Lee, Dong-Yup; Yang, Yuansheng; Lam, Kong Peng

    2014-09-01

    MicroRNAs (miRNAs) are short, non-coding RNAs that can negatively regulate expression of multiple genes at post-transcriptional levels. Using miRNAs to target multiple genes and pathways is a promising cell-engineering strategy to increase recombinant protein production in mammalian cells. Here, we identified miRs-17, -19b, -20a, and -92a to be differentially expressed between high- and low- monoclonal antibody-producing Chinese hamster ovary (CHO) cell clones using next-generation sequencing and quantitative real-time PCR. These miRNAs were stably overexpressed individually and in combination in a high-producing clone to assess their effects on CHO cell growth, recombinant protein productivity and product quality. Stably transfected pools demonstrated 24-34% increases in specific productivity (qP) and 21-31% increases in titer relative to the parental clone, without significant alterations in proliferation rates. The highest protein-producing clones isolated from these pools exhibited 130-140% increases in qP and titer compared to the parental clone, without major changes in product aggregation and N-glycosylation profile. From our clonal data, correlations between enhanced qP/titer and increased levels of miRs-17, -19b, and -92a were observed. Our results demonstrate the potential of miRs-17, -19b, and -92a as cell-engineering targets to increase recombinant protein production in mammalian cells. PMID:24819042

  19. MicroRNA-3713 regulates bladder cell invasion via MMP9

    PubMed Central

    Wu, Wen-Bo; Wang, Wei; Du, Yi-Heng; Li, Hao; Xia, Shu-Jie; Liu, Hai-Tao

    2016-01-01

    Transitional cell carcinoma (TCC) is the most common type of bladder cancer but its carcinogenesis remains not completely elucidated. Dysregulation of microRNAs (miRNAs) is well known to be involved in the development of various cancers, including TCC, whereas a role of miR-3713 in the pathogenesis of TCC has not been appreciated. Here, we reported that significantly higher levels of matrix metallopeptidase 9 (MMP9), and significantly lower levels of miR-3713 were detected in TCC tissue, compared to the adjacent non-tumor tissue, and were inversely correlated. Moreover, the low miR-3713 levels in TCC specimens were associated with poor survival of the patients. In vitro, overexpression of miR-3713 significantly decreased cell invasion, and depletion of miR-3713 increased cell invasion in TCC cells. The effects of miR-3713 on TCC cell growth appeared to result from its modification of MMP9 levels, in which miR-3713 was found to bind to the 3′-UTR of MMP9 mRNA to inhibit its protein translation in TCC cells. This study highlights miR-3713 as a previously unrecognized factor that controls TCC invasiveness, which may be important for developing innovative therapeutic targets for TCC treatment. PMID:27577949

  20. Shaping and preserving β-cell identity with microRNAs.

    PubMed

    Dumortier, O; Fabris, G; Van Obberghen, E

    2016-09-01

    The highly sophisticated identity of pancreatic β-cells is geared to accomplish its unique feat of providing insulin for organismal glucose and lipid homeostasis. This requires a particular and streamlined fuel metabolism which defines mature β-cells as glucose sensors linked to an insulin exocytosis machinery. The establishment of an appropriate β-cell mass and function during development as well as the maintenance of their identity throughout life are necessary for energy homeostasis. The small non-coding RNAs, microRNAs (miRNAs), are now well-recognized regulators of gene transcripts, which in general are negatively affected by them. Convincing evidence exists to view miRNAs as major actors in β-cell development and function, suggesting an important role for them in the distinctive β-cell 'identity card'. Here, we summarize key features that associate miRNAs and the establishment of the appropriate β-cell identity and its necessary maintenance during their 'long life'. PMID:27615131

  1. Flow bioreactor design for quantitative measurements over endothelial cells using micro-particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Leong, Chia Min; Voorhees, Abram; Nackman, Gary B.; Wei, Timothy

    2013-04-01

    Mechanotransduction in endothelial cells (ECs) is a highly complex process through which cells respond to changes in hemodynamic loading by generating biochemical signals involving gene and protein expression. To study the effects of mechanical loading on ECs in a controlled fashion, different in vitro devices have been designed to simulate or replicate various aspects of these physiological phenomena. This paper describes the design, use, and validation of a flow chamber which allows for spatially and temporally resolved micro-particle image velocimetry measurements of endothelial surface topography and stresses over living ECs immersed in pulsatile flow. This flow chamber also allows the study of co-cultures (i.e., ECs and smooth muscle cells) and the effect of different substrates (i.e., coverslip and/or polyethylene terepthalate (PET) membrane) on cellular response. In this report, the results of steady and pulsatile flow on fixed endothelial cells seeded on PET membrane and coverslip, respectively, are presented. Surface topography of ECs is computed from multiple two-dimensional flow measurements. The distributions of shear stress and wall pressure on each individual cell are also determined and the importance of both types of stress in cell remodeling is highlighted.

  2. A micro-sized bio-solar cell for self-sustaining power generation.

    PubMed

    Lee, Hankeun; Choi, Seokheun

    2015-01-21

    Self-sustainable energy sources are essential for a wide array of wireless applications deployed in remote field locations. Due to their self-assembling and self-repairing properties, "biological solar (bio-solar) cells" are recently gaining attention for those applications. The bio-solar cell can continuously generate electricity from microbial photosynthetic and respiratory activities under day-night cycles. Despite the vast potential and promise of bio-solar cells, they, however, have not yet successfully been translated into commercial applications, as they possess persistent performance limitations and scale-up bottlenecks. Here, we report an entirely self-sustainable and scalable microliter-sized bio-solar cell with significant power enhancement by maximizing solar energy capture, bacterial attachment, and air bubble volume in well-controlled microchambers. The bio-solar cell has a ~300 μL single chamber defined by laser-machined poly(methyl methacrylate) (PMMA) substrates and it uses an air cathode to allow freely available oxygen to act as an electron acceptor. We generated a maximum power density of 0.9 mW m(-2) through photosynthetic reactions of cyanobacteria, Synechocystis sp. PCC 6803, which is the highest power density among all micro-sized bio-solar cells. PMID:25367739

  3. An induction heating diamond anvil cell for high pressure and temperature micro-Raman spectroscopic measurements.

    PubMed

    Shinoda, Keiji; Noguchi, Naoki

    2008-01-01

    A new external heating configuration is presented for high-temperature diamond anvil cell instruments. The supporting rockers are thermally excited by induction from an externally mounted copper coil passing a 30 kHz alternating current. The inductive heating configuration therefore avoids the use of breakable wires, yet is capable of cell temperatures of 1100 K or higher. The diamond anvil cell has no resistive heaters, but uses a single-turn induction coil for elevating the temperature. The induction coil is placed near the diamonds and directly heats the tungsten carbide rockers that support the diamond. The temperature in the cell is determined from a temperature-power curve calibrated by the ratio between the intensities of the Stokes and anti-Stokes Raman lines of silicon. The high-pressure transformation of quartz to coesite is successfully observed by micro-Raman spectroscopy using this apparatus. The induction heating diamond anvil cell is thus a useful alternative to resistively heated diamond anvil cells. PMID:18248060

  4. MicroRNAs regulate KDM5 histone demethylases in breast cancer cells.

    PubMed

    Denis, Hélène; Van Grembergen, Olivier; Delatte, Benjamin; Dedeurwaerder, Sarah; Putmans, Pascale; Calonne, Emilie; Rothé, Françoise; Sotiriou, Christos; Fuks, François; Deplus, Rachel

    2016-02-01

    MicroRNAs (miRNAs) are small non-coding RNAs that post-transcriptionally regulate gene expression. Alteration of miRNA levels is common in tumors and contributes to the pathogenesis of human malignancies. In the present study we examined the role played by miR-137 in breast tumorigenesis. We found miR-137 levels to be lower in breast cancer cells than in their non-tumorigenic counterparts and observed reduced proliferation and migration of breast cancer cells overexpressing miR-137. We further identified KDM5B, a histone demethylase known to be involved in breast cancer tumorigenesis, as a target of miR-137. As the involvement of histone demethylases in cancer is still poorly understood and as the role of miRNAs in controlling epigenetic mechanisms in cancer is emerging, we broadened our study to the whole KDM5 histone demethylase family to see if the genes coding for these epigenetic enzymes might be regulated by miRNAs in cancer cells. We discovered that KDM5C is overexpressed in breast cancer cells, providing evidence that miR-138 regulates its expression. We found miR-138 overexpression to affect breast cancer cell proliferation. Altogether, our findings suggest that miRNAs may regulate KDM5 histone demethylase levels in breast cancer and thereby control breast cancer cell proliferation and migration. PMID:26621457

  5. Effects of α-Particle Radiation on MicroRNA Responses in Human Cell-Lines

    PubMed Central

    Chauhan, Vinita; Howland, Matthew; Wilkins, Ruth

    2012-01-01

    A variety of alpha (α)-particle emitters are found ubiquitously in the environment, in commercial/therapeutic prod-ucts and are a potential threat in the form of a radiological dispersal device. Our understanding of the biological mechanisms and long-term health effects resulting from α-particle exposure is limited. Exposure to radiation induces modulations of gene networks, possibly through microRNAs (miRNAs), which could be targets for studying biological effects. In this study, changes in miRNA expression patterns after 0.5 Gy, 1.0 Gy and 1.5 Gy of α-particle radiation at a low dose-rate of exposure in three human cell-lines (A549, THP-1 and HFL) were investigated. The screening of 1,145 miRNAs across three human cell-lines resulted in unique, cell-specific responses with no overlap in miRNA expression observed in the three cell-lines. Prediction analysis suggests these α-particle induced miRNA mapped to target genes related to ribosomal assembly, lung carcinoma development, cell communication and keratin sulfate biosynthesis. Taken together, these results suggest that exposure to α-particle radiation results in cell-type specific responses in gene network regulatory processes. PMID:22481983

  6. MicroRNAs: Novel Crossroads between Myeloma Cells and the Bone Marrow Microenvironment.

    PubMed

    Raimondi, Lavinia; De Luca, Angela; Morelli, Eugenio; Giavaresi, Gianluca; Tagliaferri, Pierosandro; Tassone, Pierfrancesco; Amodio, Nicola

    2016-01-01

    Multiple myeloma (MM) is a hematologic malignancy of differentiated plasma cells that accumulate in the bone marrow, where a complex microenvironment made by different cell types supports proliferation, survival, and drug resistance of tumor cells. MicroRNAs (miRNAs) are short non-coding RNAs that regulate gene expression at posttranscriptional level. Emerging evidence indicates that miRNAs are aberrantly expressed or functionally deregulated in MM cells as the result of multiple genetic or epigenetic mechanisms and that also the tumor microenvironment regulates MM cell functions by miRNAs. Consistently, modulation of miRNA levels in MM cells has been demonstrated to impair their functional interaction with the bone marrow microenvironment and to produce significant antitumor activity even able to overcome the protective bone marrow milieu. This review will describe the most recent findings on miRNA function in the context of MM bone marrow microenvironment, focusing on the therapeutic potential of miRNA-based approaches. PMID:26881223

  7. MicroRNAs: Novel Crossroads between Myeloma Cells and the Bone Marrow Microenvironment

    PubMed Central

    Raimondi, Lavinia; De Luca, Angela; Morelli, Eugenio; Giavaresi, Gianluca; Tagliaferri, Pierosandro; Tassone, Pierfrancesco; Amodio, Nicola

    2016-01-01

    Multiple myeloma (MM) is a hematologic malignancy of differentiated plasma cells that accumulate in the bone marrow, where a complex microenvironment made by different cell types supports proliferation, survival, and drug resistance of tumor cells. MicroRNAs (miRNAs) are short non-coding RNAs that regulate gene expression at posttranscriptional level. Emerging evidence indicates that miRNAs are aberrantly expressed or functionally deregulated in MM cells as the result of multiple genetic or epigenetic mechanisms and that also the tumor microenvironment regulates MM cell functions by miRNAs. Consistently, modulation of miRNA levels in MM cells has been demonstrated to impair their functional interaction with the bone marrow microenvironment and to produce significant antitumor activity even able to overcome the protective bone marrow milieu. This review will describe the most recent findings on miRNA function in the context of MM bone marrow microenvironment, focusing on the therapeutic potential of miRNA-based approaches. PMID:26881223

  8. MicroRNA-224 promotes the sensitivity of osteosarcoma cells to cisplatin by targeting Rac1.

    PubMed

    Geng, Shuo; Gu, Lina; Ju, Fang; Zhang, Hepeng; Wang, Yiwen; Tang, Han; Bi, ZhengGang; Yang, Chenglin

    2016-09-01

    Osteosarcoma is the most common primary bone tumour in children and adolescents. Accumulating evidence has shown that microRNAs (miRNAs) participate in the development of almost all types of cancer. Here, we investigated the role of miR-224 in the development and progression of osteosarcoma. We demonstrated that miR-224 was down-regulated in osteosarcoma cell lines and tissues. Lower miR-224 levels were correlated with shorter survivalin osteosarcoma patients. Furthermore, overexpression of miR-224 suppressed osteosarcoma cell proliferation, migration and invasion and contributed to the increased sensitivity of MG-63 cells to cisplatin. We identified Rac1 as a direct target gene of miR-224 in osteosarcoma. Rac1 expression was up-regulated in the osteosarcoma cell lines and tissues, and there was an inverse correlation between Rac1 and miR-224 expression in osteosarcoma tissues. Furthermore, rescuing Rac1 expression decreased the sensitivity of miR-224-overexpressing MG-63 cells to cisplatin. We also demonstrated that ectopic expression of Rac1 promoted the proliferation, migration and invasion of miR-224-overexpressing MG-63 cells. These data suggest that miR-224 plays a tumour suppressor role in the development of osteosarcoma and is related to the sensitivity of osteosarcoma to cisplatin. PMID:27222381

  9. MicroRNA-3713 regulates bladder cell invasion via MMP9.

    PubMed

    Wu, Wen-Bo; Wang, Wei; Du, Yi-Heng; Li, Hao; Xia, Shu-Jie; Liu, Hai-Tao

    2016-01-01

    Transitional cell carcinoma (TCC) is the most common type of bladder cancer but its carcinogenesis remains not completely elucidated. Dysregulation of microRNAs (miRNAs) is well known to be involved in the development of various cancers, including TCC, whereas a role of miR-3713 in the pathogenesis of TCC has not been appreciated. Here, we reported that significantly higher levels of matrix metallopeptidase 9 (MMP9), and significantly lower levels of miR-3713 were detected in TCC tissue, compared to the adjacent non-tumor tissue, and were inversely correlated. Moreover, the low miR-3713 levels in TCC specimens were associated with poor survival of the patients. In vitro, overexpression of miR-3713 significantly decreased cell invasion, and depletion of miR-3713 increased cell invasion in TCC cells. The effects of miR-3713 on TCC cell growth appeared to result from its modification of MMP9 levels, in which miR-3713 was found to bind to the 3'-UTR of MMP9 mRNA to inhibit its protein translation in TCC cells. This study highlights miR-3713 as a previously unrecognized factor that controls TCC invasiveness, which may be important for developing innovative therapeutic targets for TCC treatment. PMID:27577949

  10. MicroRNAs contribute to compensatory β cell expansion during pregnancy and obesity

    PubMed Central

    Jacovetti, Cécile; Abderrahmani, Amar; Parnaud, Géraldine; Jonas, Jean-Christophe; Peyot, Marie-Line; Cornu, Marion; Laybutt, Ross; Meugnier, Emmanuelle; Rome, Sophie; Thorens, Bernard; Prentki, Marc; Bosco, Domenico; Regazzi, Romano

    2012-01-01

    Pregnancy and obesity are frequently associated with diminished insulin sensitivity, which is normally compensated for by an expansion of the functional β cell mass that prevents chronic hyperglycemia and development of diabetes mellitus. The molecular basis underlying compensatory β cell mass expansion is largely unknown. We found in rodents that β cell mass expansion during pregnancy and obesity is associated with changes in the expression of several islet microRNAs, including miR-338-3p. In isolated pancreatic islets, we recapitulated the decreased miR-338-3p level observed in gestation and obesity by activating the G protein–coupled estrogen receptor GPR30 and the glucagon-like peptide 1 (GLP1) receptor. Blockade of miR-338-3p in β cells using specific anti-miR molecules mimicked gene expression changes occurring during β cell mass expansion and resulted in increased proliferation and improved survival both in vitro and in vivo. These findings point to a major role for miR-338-3p in compensatory β cell mass expansion occurring under different insulin resistance states. PMID:22996663

  11. MicroRNA-34c Expression in Donor Cells Influences the Early Development of Somatic Cell Nuclear Transfer Bovine Embryos

    PubMed Central

    Wang, Bo; Wang, Yongsheng; Zhang, Man; Du, Yue; Zhang, Yijun; Xing, Xupeng; Zhang, Lei; Su, JianMin

    2014-01-01

    Abstract The essence of the reprogramming activity of somatic cell nuclear transfer (SCNT) embryos is to produce normal fertilized embryos. However, reprogramming of somatic cells is not as efficient as the reprogramming of sperm. In this report, we describe the effect of an inducible, specific miR-34 microRNA expression in donor cells that enables a similar level of sperm:transgene expression on the early development of SCNT embryos. Our results showed that donor cells with doxycycline (dox)-induced miR-34c expression for the preparation of SCNT embryos resulted in altered developmental rates, histone modification (H3K9ac and H3K4me3), and extent of apoptosis. The cleavage rate and blastocyst formation of the induced nuclear transfer (NT) group were significantly increased. The immunofluorescence signal of H3K9ac in embryos in the induced NT group significantly increased in two-cell- and eight-cell-stage embryos; that of H3K4me3 increased significantly in eight-cell-stage embryos. Although significant differences in staining signals of apoptosis were not detected between groups, lower apoptosis levels were observed in the induced NT group. In conclusion, miR-34c expression induced by dox treatment enhances the developmental potential of SCNT embryos, modifies the epigenetic status, and changes blastocyst quality. PMID:25437869

  12. Transdifferentiation of periodontal ligament-derived stem cells into retinal ganglion-like cells and its microRNA signature

    PubMed Central

    Ng, Tsz Kin; Yung, Jasmine S. Y.; Choy, Kwong Wai; Cao, Di; Leung, Christopher K. S.; Cheung, Herman S.; Pang, Chi Pui

    2015-01-01

    Retinal diseases are the leading causes of irreversible visual impairment and blindness in the developed countries. Human retina has limited regenerative power to replace cell loss. Stem cell replacement therapy has been proposed as a viable option. Previously, we have induced human adult periodontal ligament stem cells (PDLSCs) to the retinal lineage. In this study, we modified our induction protocol to direct human adult PDLSCs into retinal ganglion-like cells and determined the microRNA (miRNA) signature of this transdifferentiation process. The differentiated PDLSCs demonstrated the characteristics of functional neurons as they expressed neuronal and retinal ganglion cell markers (ATOH7, POU4F2, β-III tubulin, MAP2, TAU, NEUROD1 and SIX3), formed synapses and showed glutamate-induced calcium responses as well as spontaneous electrical activities. The global miRNA expression profiling identified 44 upregulated and 27 downregulated human miRNAs after retinal induction. Gene ontology analysis of the predicted miRNA target genes confirmed the transdifferentiation is closely related to neuronal differentiation processes. Furthermore, the expressions of 2 miRNA-targeted candidates, VEGF and PTEN, were significantly upregulated during the induction process. This study identified the transdifferentiation process of human adult stem cells into retinal ganglion-like cells and revealed the involvement of both genetic and miRNA regulatory mechanisms. PMID:26549845

  13. A versatile micro-mechanical tester for actin stress fibers isolated from cells.

    PubMed

    Matsui, Tsubasa S; Deguchi, Shinji; Sakamoto, Naoya; Ohashi, Toshiro; Sato, Masaaki

    2009-01-01

    Conventional atomic force microscopy is one of the major techniques to evaluate mechanical properties of cells and subcellular components. The use of a cantilever probe for sample manipulation within the vertical plane often makes absolute positioning of the probe, subject to thermal drift, difficult. In addition, the vertical test is unable to observe changes in the sample structure responsible for mechanical behavior detected by the probe. In the present study, an alternative mechanical tester was developed that incorporated a pair of micro-needles to manipulate a sample in a project plane, allowing acquisition of the accurate probe position and entire sample image. Using a vision-based feedback control, a micro-needle driven by a piezo actuator is moved to give user-defined displacements or forces to sample. To show its usefulness and versatility, three types of viscoelastic measurements on actin stress fibers isolated from smooth muscle cells were demonstrated: strain rate-controlled tensile tests, relaxation tests and creep tests. Fluorescence imaging of the stress fibers using Qdots over the course of the measurements, obtained through multiple image detectors, was also carried out. The technique described here is useful for examining the quantitative relationship between mechanical behavior and related structural changes of biomaterials. PMID:19940356

  14. Laser machined macro and micro structures on glass for enhanced light trapping in solar cells

    NASA Astrophysics Data System (ADS)

    Moore, David; Rahman, Mahfujur; Dowling, Denis P.; McNally, Patrick J.; Brabazon, Dermot

    2013-03-01

    In order to increase the efficiency of solar cell modules it is necessary to make the optimum use of light incident upon them. Much research has been done on improving light absorption through front surface texturisation and light trapping schemes. Laser light is commonly used in industry for various applications including marking and texturisation. By controlling laser parameters, it is possible to tailor macro and micro structures in most materials. The CO2 laser used in this investigation emits radiation at 10.6 μm with the ability to pulse in the micro-second range. The laser was used to ablate grooved textures in the fused quartz material, used in this study as the light trapping medium, following which an analysis of the effects of the laser parameters on the texture geometry and surface morphology was performed through a combination of cross sectioning and scanning electron microscopy. Transmission through the textured glass was improved for most samples after acid etching. The light trapping effects of the best performing textures were analysed by investigating the effects on a silicon solar cell's performance at varying angles of incidence. Results indicated a significant increase in light trapping when light was incident at acute angles. For an angle of incidence of 10∘ a relative increase in efficiency of up to 51 % was observed.

  15. Accelerated testing of solid oxide fuel cell stacks for micro combined heat and power application

    NASA Astrophysics Data System (ADS)

    Hagen, Anke; Høgh, Jens Valdemar Thorvald; Barfod, Rasmus

    2015-12-01

    State-of-the-art (SoA) solid oxide fuel cell (SOFC) stacks are tested using profiles relevant for use in micro combined heat and power (CHP) units. Such applications are characterised by dynamic load profiles. In order to shorten the needed testing time and to investigate potential acceleration of degradation, the profiles are executed faster than required for real applications. Operation with fast load cycling, both using hydrogen and methane/steam as fuels, does not accelerate degradation compared to constant operation, which demonstrates the maturity of SoA stacks and enables transferring knowledge from testing at constant conditions to dynamic operation. 7.5 times more cycles than required for 80,000 h lifetime as micro CHP are achieved on one-cell-stack level. The results also suggest that degradation mechanisms that proceed on a longer time-scale, such as creep, might have a more dominating effect for long life-times than regular short time changes of operation. In order to address lifetime testing it is suggested to build a testing program consisting of defined modules that represent different application profiles, such as one module at constant conditions, followed by modules at one set of dynamic conditions etc.

  16. [Relationships between microRNA expressions and prognosis in patients with tongue squamous cell carcinoma and the mechanisms microRNA regulating tongue squamous cell carcinoma biological behavior].

    PubMed

    Jia, Ling-fei; Gan, Ye-hua; Yu, Guang-yan

    2016-02-18

    Tongue squamous cell carcinoma (TSCC) is the most common type of oral cancer and is well known for its high rate of proliferation and lymph nodal metastasis. Exploring the underlying pathways regulating TSCC could provide novel ideas for diagnosis and prognosis of TSCC patients, as well as molecular targets for treatment of TSCC. MicroRNAs (miRNAs) are small noncoding RNAs that inhibit gene expression through the 3' untranslated regions (3'UTRs) of their target messenger RNAs. They play crucial roles in numerous biological processes, including cancer progression. Although great efforts have been made, what role miRNAs may play in the early detection and diagnosis of TSCC is not fully understood. Recently, our team has performed a series of basic and clinical researches in an attempt to investigate the relationships between miRNA expressions and prognosis of patients with TSCC and the mechanisms under regulation of TSCC. The results showed that miR-195, miR-34a, miR-29b, miR-375 and miR-26a could inhibit TSCC cells progression and development via a sophisticated network of genes. Specifically, the anti-tumor effects of miR-195 in TSCC may be partially mediated by its inhibition of CyclinD1 and Bcl-2 expression. The expression of miR-34a could inhibit migration and invasion of TSCC cell lines via targeting MMP9 and MMP14. The function of miR-29b may be through the miR-29b/Sp1/PTEN/AKT axis. Overexpression of miR-375 inhibited Sp1 expression by targeting the 3' untranslated region of the Sp1 transcript. MEG3 and miR-26a inhibited TSCC cell proliferation, cycle progression and promoted cell apoptosis and miR-26a could increase the MEG3 expression through reduction of the expression of DNMT3B in TSCC. In light of the role of those miRNAs in diagnosis and prognosis of TSCC, we reported that decreased miR-195 and miR-375 expression was associated with poor overall survival rate of the TSCC patients, while miR-34a expression was negatively correlated with cervical lymph

  17. Performance and analysis of amorphous silicon p-i-n solar cells made by chemical-vapor deposition from disilane

    SciTech Connect

    Hegedus, S.S.; Rocheleau, R.E.; Buchanan, W.; Baron, B.N.

    1987-01-01

    The photovoltaic performance of amorphous silicon p-i-n solar cells made by chemical-vapor deposition (CVD) from disilane is reported and analyzed. Intrinsic layers were deposited at rates from 0.2 to 50 A/s at temperatures from 380 to 460 /sup 0/C with and without boron doping. Device performance was insensitive to substantial differences in disilane purity. A cell efficiency of 4% was achieved. The primary limitation to higher efficiency was low fill factor (<50%) due to high series resistance (>18 ..cap omega.. cm/sup 2/). Analysis of the series resistance indicated a contact-related resistance of 4--12 ..cap omega.. cm/sup 2/ and a photoconductive resistance composed of intrinsic layer thickness-independent (10 ..cap omega.. cm/sup 2/) and thickness-dependent terms. Analysis of the voltage dependence of the current collection indicated a fill factor of 60% would be expected in the absence of series resistance. The maximum short-circuit current of 12.5 mA/cm/sup 2/ (normalized to 100 mW/cm/sup 2/) resulted with a boron-doped i layer deposited at 440 /sup 0/C at 3.3 A/s. Modeling of the collection efficiency indicated collection widths up to 0.33 ..mu..m for boron-doped and 0.24 ..mu..m for undoped p-i-n devices. In order to achieve high-efficiency cells using CVD from disilane, the limitations imposed by low photoconductivity, a high density of states, and restricted cell design imposed by the high deposition temperatures would have to be overcome.

  18. MicroRNA-340 Inhibits Tumor Cell Proliferation and Induces Apoptosis in Endometrial Carcinoma Cell Line RL 95-2.

    PubMed

    Xie, Wei; Qin, Wen; Kang, Yalin; Zhou, Ziyan; Qin, Aiping

    2016-01-01

    BACKGROUND The purpose of our study was to investigate the functional role of microRNA-340 (miR-340) in endometrial carcinoma (EC). MATERIAL AND METHODS Human EC cell line RL 95-2 was transfected with miR-340 mimics, inhibitors, or controls. After 48 h of transfection, the cell viability was determined by 3-(4, 5-dimethyl-2- thiazolyl)-2, 5-diphenyl -2-H-tetrazolium bromide (MTT) assay. The BrdU assay and apoptosis assay were performed to determine the effects of miR-340 mimics or inhibitors on cell proliferation and apoptosis, respectively. The underlying mechanisms involved in cell proliferation and apoptosis were explored by measuring the protein levels of cell cycle regulators (p27 kinase inhibition protein (KIP) 1 and p21) and apoptosis-related factors (B-cell lymphoma-2 (Bcl-2), Bax, pro-Caspase 3, and active-Caspase-3). RESULTS Overexpression of miR-340 significantly inhibited the cell viability (P<0.05) and cell proliferation (P<0.01) of RL 95-2 cells compared with the control group, but increased the apoptosis (P<0.01). However, suppression of miR-340 had opposite results. Moreover, the protein levels of p27 KIP1, Bax, pro-Caspase 3, and active-Caspase-3 were significantly increased by overexpression of miR-340 but were statistically decreased by suppression of miR-340. Contrary results were found in the protein levels of Bcl-2. However, no significant differences were found in p21 expression. CONCLUSIONS MiRNA-340 acts as an anti-oncogene in EC cell line RL 95-2 by inhibition of tumor cell proliferation and induction of apoptosis. PMID:27153225

  19. MicroRNA-340 Inhibits Tumor Cell Proliferation and Induces Apoptosis in Endometrial Carcinoma Cell Line RL 95-2

    PubMed Central

    Xie, Wei; Qin, Wen; Kang, Yalin; Zhou, Ziyan; Qin, Aiping

    2016-01-01

    Background The purpose of our study was to investigate the functional role of microRNA-340 (miR-340) in endometrial carcinoma (EC). Material/Methods Human EC cell line RL 95-2 was transfected with miR-340 mimics, inhibitors, or controls. After 48 h of transfection, the cell viability was determined by 3-(4, 5-dimethyl-2- thiazolyl)-2, 5-diphenyl -2-H-tetrazolium bromide (MTT) assay. The BrdU assay and apoptosis assay were performed to determine the effects of miR-340 mimics or inhibitors on cell proliferation and apoptosis, respectively. The underlying mechanisms involved in cell proliferation and apoptosis were explored by measuring the protein levels of cell cycle regulators (p27 kinase inhibition protein (KIP) 1 and p21) and apoptosis-related factors (B-cell lymphoma-2 (Bcl-2), Bax, pro-Caspase 3, and active-Caspase-3). Results Overexpression of miR-340 significantly inhibited the cell viability (P<0.05) and cell proliferation (P<0.01) of RL 95-2 cells compared with the control group, but increased the apoptosis (P<0.01). However, suppression of miR-340 had opposite results. Moreover, the protein levels of p27 KIP1, Bax, pro-Caspase 3, and active-Caspase-3 were significantly increased by overexpression of miR-340 but were statistically decreased by suppression of miR-340. Contrary results were found in the protein levels of Bcl-2. However, no significant differences were found in p21 expression. Conclusions MiRNA-340 acts as an anti-oncogene in EC cell line RL 95-2 by inhibition of tumor cell proliferation and induction of apoptosis. PMID:27153225

  20. MicroRNA-141 inhibits vascular smooth muscle cell proliferation through targeting PAPP-A

    PubMed Central

    Zhang, Yudong; Chen, Bainan; Ming, Liu; Qin, Hongsong; Zheng, Liu; Yue, Zhang; Cheng, Zhixin; Wang, Yannan; Zhang, Dawei; Liu, Chunmei; Bin, Wang; Hao, Qingzhi; Song, Fuchen; Ji, Bo

    2015-01-01

    It is well known that ox-LDL plays key roles in the development of atherosclerosis, partly by inducing vascular smooth muscle cells (VSMCs) proliferation. Recent findings have revealed that microRNAs, a class of small noncoding RNAs, could regulate cell proliferation in many physiological and pathological conditions. However, the role and function of miRNAs on ox-LDL induced VSMC proliferation are not fully elucidated. In this study, we showed that ox-LDL could suppress miR-141 expression and inhibition of miR-141 could promote VSMCs proliferation. Moreover, we found that PAPPA was the direct target gene of miR-141. Overexpression of PAPPA impaired the miR-141-induced inhibition of proliferation in the VSMCs. Taken together; miR-141 may play important roles in ox-LDL-induced abnormal proliferation of the VSMC. PMID:26823756

  1. Bioenergetic disruption of human micro-vascular endothelial cells by antipsychotics.

    PubMed

    Elmorsy, Ekramy; Smith, Paul A

    2015-05-01

    Antipsychotics (APs) are widely used medications, however these are not without side effects such as disruption of blood brain barrier function (BBB). To investigate this further we have studied the chronic effects of the typical APs, chlorpromazine (CPZ) and haloperidol (HAL) and the atypical APs, risperidone (RIS) and clozapine (CLZ), on the bioenergetics of human micro-vascular endothelial cells (HBVECs) of the BBB. Alamar blue (AB) and ATP assays showed that these APs impair bioenergenesis in HBVECs in a concentration and time dependent manner. However since these effects were incomplete they suggest a population of cell bioenergetically heterogeneous, an idea supported by the bistable nature by which APs affected the mitochondrial transmembrane potential. CPZ, HAL and CLZ inhibited the activity of mitochondrial complexes I and III. Our data demonstrates that at therapeutic concentrations, APs can impair the bioenergetic status of HBVECs, an action that help explains the adverse side effects of these drugs when used clinically. PMID:25824037

  2. MicroRaman Spectroscopy and Raman Imaging of Basal Cell Carcinoma

    NASA Astrophysics Data System (ADS)

    Short, M. A.; Zeng, H.; Lui, H.

    2005-03-01

    We have measured the Raman spectra of normal and cancerous skin tissues using a confocal microRaman spectrograph with a sub-micron spatial resolution. We found that the Raman spectrum of a cell nucleolus is different from the spectra measured outside the nucleolus and considerably different from those measured outside the nucleus. In addition, we found significant spectroscopic differences between normal and cancer-bearing sites in the dermis region. In order to utilize these differences for non-invasive skin cancer diagnosis, we have developed a Raman imaging system that clearly demonstrates the structure, location and distribution of cells in unstained skin biopsy samples. Our method is expected to be useful for the detection and characterization of skin cancer based on the known distinct cellular differences between normal and malignant skin.

  3. MicroRNA-21 promotes cell proliferation and down-regulates the expression of programmed cell death 4 (PDCD4) in HeLa cervical carcinoma cells

    SciTech Connect

    Yao, Qing; Xu, Hui; Zhang, Qian-Qian; Zhou, Hui; Qu, Liang-Hu

    2009-10-23

    MicroRNAs are involved in cancer-related processes. The microRNA-21(miR-21) has been identified as the only miRNA over-expressed in a wide variety of cancers, including cervical cancer. However, the function of miR-21 is unknown in cervical carcinomas. In this study, we found that the inhibition of miR-21 in HeLa cervical cancer cells caused profound suppression of cell proliferation, and up-regulated the expression of the tumor suppressor gene PDCD4. We also provide direct evidence that PDCD4-3'UTR is a functional target of miR-21 and that the 18 bp putative target site can function as the sole regulatory element in HeLa cells. These results suggest that miR-21 may play an oncogenic role in the cellular processes of cervical cancer and may serve as a target for effective therapies.

  4. Atomic-scale modeling of chemical vapor deposition processes from new complicated gas-phase mixtures for micro- and nanoelectronic applications

    NASA Astrophysics Data System (ADS)

    Makhviladze, T. M.; Sarychev, M. E.

    2009-01-01

    Low-pressure chemical vapor deposition (CVD) is one of the most important processes for obtaining thin films widely used in semiconductor and in IC technology. Because of the baffling complexity of deposition process the usually-used approaches in CVD modeling include a great number of empiric non-calculated parameters, and this drawback becomes a grave disadvantage if one needs to model the process with new reagents and materials which were not used before. So we place primary emphasis upon the development of non-empirical deposition models that rely on phenomenological theories and experimental data only to a minimal extent. We are presenting the atomistic-scale models and software package throughout the entire deposition process that are based mainly on the first principles and ab initio methods. The main modeling stages are studied and discussed in detail, namely: atomistic modeling of gas-phase and surface reactions, determination of the basic chemical and physical mechanisms for the considered gas mixtures, calculations of the reactions rates for elementary reactions and acts, Monte Carlo and/or molecular dynamics simulation of the thin film growth, and modeling of macrokinetic processes in realistic deposition flow-reactor chamber. The modeling results for thin films deposition from actual gas mixtures are given. The physical properties of films as well as their stoichiometric composition and structure in dependence of process conditions are discussed.

  5. The microRNA-132 and microRNA-212 cluster regulates hematopoietic stem cell maintenance and survival with age by buffering FOXO3 expression

    PubMed Central

    Mehta, Arnav; Zhao, Jimmy L.; Sinha, Nikita; Marinov, Georgi K.; Mann, Mati; Kowalczyk, Monika S.; Galimidi, Rachel P.; Du, Xiaomi; Erikci, Erdem; Regev, Aviv; Chowdhury, Kamal; Baltimore, David

    2015-01-01

    Summary MicroRNAs are critical post-transcriptional regulators of hematopoietic cell-fate decisions, though little remains known about their role in aging hematopoietic stem cells (HSCs). We found that the microRNA-212/132 cluster (Mirc19) is enriched in HSCs and is up-regulated during aging. Both over-expression and deletion of microRNAs in this cluster leads to inappropriate hematopoiesis with age. Enforced expression of miR-132 in the bone marrow of mice led to rapid HSC cycling and depletion. A genetic deletion of Mirc19 in mice resulted in HSCs that had altered cycling, function, and survival in response to growth factor starvation. We found that miR-132 exerted its effect on aging HSCs by targeting the transcription factor FOXO3, a known aging associated gene. Our data demonstrates that Mirc19 plays a role in maintaining balanced hematopoietic output by buffering FOXO3 expression. We have thus identified it as a potential target that may play a role in age-related hematopoietic defects. PMID:26084022

  6. MicroRNA-21 Exhibits Antiangiogenic Function by Targeting RhoB Expression in Endothelial Cells

    PubMed Central

    Bovy, Nicolas; Deroanne, Christophe; Lambert, Vincent; Gonzalez, Maria-Luz Alvarez; Colige, Alain; Rakic, Jean-Marie; Noël, Agnès; Martial, Joseph A.; Struman, Ingrid

    2011-01-01

    Background MicroRNAs (miRNAs) are endogenously expressed small non-coding RNAs that regulate gene expression at post-transcriptional level. The recent discovery of the involvement of these RNAs in the control of angiogenesis renders them very attractive in the development of new approaches for restoring the angiogenic balance. Whereas miRNA-21 has been demonstrated to be highly expressed in endothelial cells, the potential function of this miRNA in angiogenesis has never been investigated. Methodology/Principal Findings We first observed in endothelial cells a negative regulation of miR-21 expression by serum and bFGF, two pro-angiogenic factors. Then using in vitro angiogenic assays, we observed that miR-21 acts as a negative modulator of angiogenesis. miR-21 overexpression reduced endothelial cell proliferation, migration and the ability of these cells to form tubes whereas miR-21 inhibition using a LNA-anti-miR led to opposite effects. Expression of miR-21 in endothelial cells also led to a reduction in the organization of actin into stress fibers, which may explain the decrease in cell migration. Further mechanistic studies showed that miR-21 targets RhoB, as revealed by a decrease in RhoB expression and activity in miR-21 overexpressing cells. RhoB silencing impairs endothelial cell migration and tubulogenesis, thus providing a possible mechanism for miR-21 to inhibit angiogenesis. Finally, the therapeutic potential of miR-21 as an angiogenesis inhibitor was demonstrated in vivo in a mouse model of choroidal neovascularization. Conclusions/Significance Our results identify miR-21 as a new angiogenesis inhibitor and suggest that inhibition of cell migration and tubulogenesis is mediated through repression of RhoB. PMID:21347332

  7. MicroRNA-27a Contributes to Rhabdomyosarcoma Cell Proliferation by Suppressing RARA and RXRA

    PubMed Central

    Tombolan, Lucia; Zampini, Matteo; Casara, Silvia; Boldrin, Elena; Zin, Angelica; Bisogno, Gianni; De Pittà, Cristiano; Lanfranchi, Gerolamo

    2015-01-01

    Background Rhabdomyosarcomas (RMS) are rare but very aggressive childhood tumors that arise as a consequence of a regulatory disruption in the growth and differentiation pathways of myogenic precursor cells. According to morphological criteria, there are two major RMS subtypes: embryonal RMS (ERMS) and alveolar RMS (ARMS) with the latter showing greater aggressiveness and metastatic potential with respect to the former. Efforts to unravel the complex molecular mechanisms underlying RMS pathogenesis and progression have revealed that microRNAs (miRNAs) play a key role in tumorigenesis. Methodology/Principal Findings The expression profiles of 8 different RMS cell lines were analyzed to investigate the involvement of miRNAs in RMS. The miRNA population from each cell line was compared to a reference sample consisting of a balanced pool of total RNA extracted from those 8 cell lines. Sixteen miRNAs whose expression discriminates between translocation-positive ARMS and negative RMS were identified. Attention was focused on the role of miR-27a that is up-regulated in the more aggressive RMS cell lines (translocation-positive ARMS) in which it probably acts as an oncogene. MiR-27a overexpressing cells showed a significant increase in their proliferation rate that was paralleled by a decrease in the number of cells in the G1 phase of the cell cycle. It was possible to demonstrate that miR-27a is implicated in cell cycle control by targeting the retinoic acid alpha receptor (RARA) and retinoic X receptor alpha (RXRA). Conclusions Study results have demonstrated that miRNA expression signature profiling can be used to classify different RMS subtypes and suggest that miR-27a may have a therapeutic potential in RMS by modulating the expression of retinoic acid receptors. PMID:25915942

  8. Cell motility regulation on a stepped micro pillar array device (SMPAD) with a discrete stiffness gradient.

    PubMed

    Lee, Sujin; Hong, Juhee; Lee, Junghoon

    2016-02-28

    Our tissues consist of individual cells that respond to the elasticity of their environment, which varies between and within tissues. To better understand mechanically driven cell migration, it is necessary to manipulate the stiffness gradient across a substrate. Here, we have demonstrated a new variant of the microfabricated polymeric pillar array platform that can decouple the stiffness gradient from the ECM protein area. This goal is achieved via a "stepped" micro pillar array device (SMPAD) in which the contact area with the cell was kept constant while the diameter of the pillar bodies was altered to attain the proper mechanical stiffness. Using double-step SU-8 mold fabrication, the diameter of the top of every pillar was kept uniform, whereas that of the bottom was changed, to achieve the desired substrate rigidity. Fibronectin was immobilized on the pillar tops, providing a focal adhesion site for cells. C2C12, HeLa and NIH3T3 cells were cultured on the SMPAD, and the motion of the cells was observed by time-lapse microscopy. Using this simple platform, which produces a purely physical stimulus, we observed that various types of cell behavior are affected by the mechanical stimulus of the environment. We also demonstrated directed cell migration guided by a discrete rigidity gradient by varying stiffness. Interestingly, cell velocity was highest at the highest stiffness. Our approach enables the regulation of the mechanical properties of the polymeric pillar array device and eliminates the effects of the size of the contact area. This technique is a unique tool for studying cellular motion and behavior relative to various stiffness gradients in the environment. PMID:26787193

  9. Next-generation sequencing identifies the natural killer cell microRNA transcriptome

    PubMed Central

    Fehniger, Todd A.; Wylie, Todd; Germino, Elizabeth; Leong, Jeffrey W.; Magrini, Vincent J.; Koul, Sunita; Keppel, Catherine R.; Schneider, Stephanie E.; Koboldt, Daniel C.; Sullivan, Ryan P.; Heinz, Michael E.; Crosby, Seth D.; Nagarajan, Rakesh; Ramsingh, Giridharan; Link, Daniel C.; Ley, Timothy J.; Mardis, Elaine R.

    2010-01-01

    Natural killer (NK) cells are innate lymphocytes important for early host defense against infectious pathogens and surveillance against malignant transformation. Resting murine NK cells regulate the translation of effector molecule mRNAs (e.g., granzyme B, GzmB) through unclear molecular mechanisms. MicroRNAs (miRNAs) are small noncoding RNAs that post-transcriptionally regulate the translation of their mRNA targets, and are therefore candidates for mediating this control process. While the expression and importance of miRNAs in T and B lymphocytes have been established, little is known about miRNAs in NK cells. Here, we used two next-generation sequencing (NGS) platforms to define the miRNA transcriptomes of resting and cytokine-activated primary murine NK cells, with confirmation by quantitative real-time PCR (qRT-PCR) and microarrays. We delineate a bioinformatics analysis pipeline that identified 302 known and 21 novel mature miRNAs from sequences obtained from NK cell small RNA libraries. These miRNAs are expressed over a broad range and exhibit isomiR complexity, and a subset is differentially expressed following cytokine activation. Using these miRNA NGS data, miR-223 was identified as a mature miRNA present in resting NK cells with decreased expression following cytokine activation. Furthermore, we demonstrate that miR-223 specifically targets the 3′ untranslated region of murine GzmB in vitro, indicating that this miRNA may contribute to control of GzmB translation in resting NK cells. Thus, the sequenced NK cell miRNA transcriptome provides a valuable framework for further elucidation of miRNA expression and function in NK cell biology. PMID:20935160

  10. Pancreatic islet differentiation of human embryonic stem cells by microRNA overexpression.

    PubMed

    Lahmy, Reyhaneh; Soleimani, Masoud; Sanati, Mohammad H; Behmanesh, Mehrdad; Kouhkan, Fatemeh; Mobarra, Naser

    2016-06-01

    Development of stem cell-based therapies for the treatment of type 1 diabetes would provide a renewable supply of human β-cells. Human embryonic stem cells (ESCs) are considered to be one of the stem cell populations with sufficient proliferative capacity to achieve this goal. Currently, differentiation protocols directing ESCs toward a pancreatic fate employ a variety of expensive cytokines and inhibitors. With the known significance of microRNAs in islet development, we present a novel and cost-effective strategy in which miR-375 overexpression promotes pancreatic endocrine differentiation in hESCs in the absence of any extrinsic factors. miR-375 has been shown to be a key regulator of pancreatic development and function in zebrafish, mouse and human. In this study, hESCs were transduced with lentiviral vectors containing human miR-375 precursor and aggregated to form human embryoid bodies (hEBs) for up to 21 days. Morphological assessment, immunocytochemistry and DTZ staining confirmed that miR-375-induced hEBs have similar characteristics to those of mature islets. In addition, the dynamic expression profile of endodermal marker Foxa2 and endocrine-specific genes, including HNF4α, Pdx1, Pax6, Nkx6.1, Glut2 and insulin, were detected by quantitative real-time PCR. Finally, insulin release upon glucose stimulation was detected in our differentiated clusters. The data presented here demonstrate the feasibility of using microRNAs to direct differentiation into the pancreatic lineage. Copyright © 2013 John Wiley & Sons, Ltd. PMID:23897763

  11. Sustained delivery of proangiogenic microRNA-132 by nanoparticle transfection improves endothelial cell transplantation

    PubMed Central

    Devalliere, Julie; Chang, William G.; Andrejecsk, Jillian W.; Abrahimi, Parwiz; Cheng, Christopher J.; Jane-wit, Dan; Saltzman, W. Mark; Pober, Jordan S.

    2014-01-01

    Transplantation of endothelial cells (ECs) for therapeutic vascularization or tissue engineering is a promising method for increasing tissue perfusion. Here, we report on a new approach for enhanced EC transplantation using targeted nanoparticle transfection to deliver proangiogenic microRNA-132 (miR-132) to cultured ECs before their transplantation, thereby sensitizing cells to the effects of endogenous growth factors. We synthesized biodegradable PLGA polymer nanoparticles (NPs) that were loaded with miR-132 and coated with cyclic RGD (cRGD) peptides that target integrin αvβ3 expressed on cultured human umbilical vein ECs (HUVECs), increasing NP uptake through clathrin-coated pits. Unlike previously reported NPs for miR delivery, these NPs slowly release RNA for several weeks. The endocytosed NPs remain in clathrin-coated vesicles from which they mediate intracellular delivery of siRNA or miRNA. Transfection of HUVECs with miR-132 enhances growth factor-induced proliferation and migration in 2D culture, producing a 1.8- and 5-fold increase, respectively. However, while the effects of conventional transfection were short-lived, NP transfection produced protein knockdown and biological effects that were significantly longer in duration (≥6 d). Transfection of HUVECs with miR-132 NP resulted in a 2-fold increase in the number of microvessels per square millimeter compared to lipid after transplantation into immunodeficient mice and led to a higher number of mural cell-invested vessels than control transfection. These data suggest that sustained delivery of miR-132 encapsulated in a targeted biodegradable polymer NP is a safe and efficient strategy to improve EC transplantation and vascularization.—Devalliere, J., Chang, W. G., Andrejecsk, J. W., Abrahimi, P., Cheng, C. J., Jane-wit, D., Saltzman, W. M., Pober, J. S. Sustained delivery of proangiogenic microRNA-132 by nanoparticle transfection improves endothelial cell transplantation. PMID:24221087

  12. MicroRNA modulation induced by AICA ribonucleotide in J1 mouse ES cells.

    PubMed

    Shi, Xiaoyan; YongyanWu; Ai, Zhiying; Du, Juan; Cao, Lixia; Guo, Zekun; Zhang, Yong

    2014-01-01

    ES cells can propagate indefinitely, maintain self-renewal, and differentiate into almost any cell type of the body. These properties make them valuable in the research of embryonic development, regenerative medicine, and organ transplantation. MicroRNAs (miRNAs) are considered to have essential functions in the maintenance and differentiation of embryonic stem cells (ES cells). It was reported that, strong external stimuli, such as a transient low-pH and hypoxia stress, were conducive to the formation of induced pluripotent stem cells (iPS cells). AICA ribonucleotide (AICAR) is an AMP-activated protein kinase activator, which can let cells in the state of energy stress. We have demonstrated that AICAR can maintain the pluripotency of J1 mouse ES cells through modulating protein expression in our previous research, but its effects on ES cell miRNA expression remain unknown. In this study, we conducted small RNA high-throughput sequencing to investigate AICAR influence on J1 mouse ES cells by comparing the miRNA expression patterns of the AICAR-treated cells and those without treatment. The result showed that AICAR can significantly modulate the expression of multiple miRNAs, including those have crucial functions in ES cell development. Some differentially expressed miRNAs were selected and confirmed by real-time PCR. For the differently expressed miRNAs identified, further study was conducted regarding the pluripotency and differentiation associated miRNAs with their targets. Moreover, miR-134 was significantly down-regulated after AICAR treatment, and this was suggested to be directly associated with the up-regulated pluripotency markers, Nanog and Sox2. Lastly, Myc was significantly down-regulated after AICAR treatment; therefore, we predicted miRNAs that may target Myc and identified that AICAR induced up-regulation of miR-34a, 34b, and 34c can repress Myc expression in J1 mouse ES cells. Taken together, our study provide a new mechanism for AICAR in ES cells

  13. Identification of microRNA profiles in salivary adenoid cystic carcinoma cells during metastatic progression.

    PubMed

    Chen, Wei; Zhao, Xiaoge; Dong, Zhen; Cao, Gang; Zhang, Senlin

    2014-06-01

    Salivary adenoid cystic carcinoma (SACC) is a common type of salivary gland cancer. The poor long-term prognosis of patients with SACC is primarily due to local recurrence, distant metastasis and perineural invasion. MicroRNAs (miRNAs) have been identified as important post-transcriptional regulators, which are involved in various biological processes. The aim of the present study was to identify the miRNA expression profiles that are involved in the metastatic progression of SACC. Therefore, microarray technology was employed to identify miRNA expression profiles in an SACC cell line, ACC-2, and a highly metastatic SACC cell line, ACC-M, which was screened from ACC-2 by a combination of in vivo selection and cloning in vitro. Differences in miRNA expression were assessed by quantitative polymerase chain reaction (qPCR) assay. In addition, the potential target genes that are regulated by selected miRNAs were analyzed by various target prediction tools. The microarray data revealed that the levels of 38 miRNAs significantly differed between the ACC-M cells and the control ACC-2 cells. Six miRNAs (miR-4487, -4430, -486-3p, -5191, -3131 and -211-3p) were selected to validate the microarray data via qPCR. The expression of two miRNAs (miR-4487 and -4430) was significantly upregulated in the ACC-M cells, while the expression of two other miRNAs (miR-5191 and -3131) was significantly downregulated in the ACC-M cells. The potential target genes that were identified to be controlled by the six selected miRNAs were divided into four groups according to function, as follows: Apoptosis and proliferation (46 genes), cell cycle (30 genes), DNA damage and repair (24 genes) and signaling pathway (30 genes). The identification of microRNA expression profiles in highly metastatic SACC cells may provide an improved understanding of the mechanisms involved in metastatic progression, which would aid in the development of novel strategies for the treatment of SACC. PMID:24932284

  14. Arrays of EAP micro-actuators for single-cell stretching applications

    NASA Astrophysics Data System (ADS)

    Akbari, S.; Niklaus, M.; Shea, H.

    2010-04-01

    Mechanical stimuli are critical for the development and maintenance of most tissues such as muscles, cartilage, bones and blood vessels. The commercially available cell culture systems replicating the in vivo environment are typically based on simple membrane cell-stretching equipment, which can only measure the average response of large colonies of cells over areas of greater than one cm2. We present here the conceptual design and the complete fabrication process of an array of 128 Electro-Active Polymer (EAP) micro-actuators which are uni-axially stretched and hence used to impose unidirectional strain on single cells, make it feasible to do experiments on the cytomechanics of individual cells. The Finite Element Method is employed to study the effect of different design parameters on achievable strain, leading to the optimized design. Compliant gold electrodes are deposited by low-energy ion implantation on both sides of a PDMS membrane, as this technique allows making electrodes that support large strain with minimal stiffening of the elastomer. The membrane is bonded to a rigid support, leading to an array of 100×100 μm2 EAP actuators.

  15. Three-Dimensional Characterization of Cell Clusters Using Synchrotron-Radiation-Based Micro-Computed Tomography

    NASA Astrophysics Data System (ADS)

    Müller, Ert; Riedel, Marco; Thurner, Philipp J.

    2006-04-01

    Micro-computed tomography with the highly intense, monochromatic X rays produced by the synchrotron is a superior method to nondestructively measure the local absorption in three-dimensional space. Because biological tissues and cells consist mainly of water as the surrounding medium, higher absorbing agents have to be incorporated into the structures of interest. Even without X-ray optics such as refractive lens, one can uncover the stain distribution with the spatial resolution of about 1 [mu]m. Incorporating the stain at selected cell compartments, for example, binding to the RNA/DNA, their density distribution becomes quantified. In this communication, we demonstrate that tomograms obtained at the beamlines BW2 and W2 (HASYLAB at DESY, Hamburg, Germany) and 4S (SLS, Villigen, Switzerland) clearly show that the RNA/DNA-stained HEK 293 cell clusters have a core of high density and a peripheral part of lower density, which correlate with results of optical microscopy. The inner part of the clusters is associated with nonvital cells as the result of insufficient oxygen and nutrition supply. This necrotic part is surrounded by (6 ± 1) layers of vital cells.

  16. Geometric classification of open-cell metal foams using X-ray micro-computed tomography

    SciTech Connect

    Bock, Jessica Jacobi, Anthony M.

    2013-01-15

    The geometry of foams has long been an area of interest, and a number of idealized geometric descriptions have been proposed. In order to acquire detailed, quantitative, geometric data for aluminum open-cell metal foams, X-ray {mu}CT is employed. The X-ray {mu}CT images are analyzed using specialized software, FoamView Registered-Sign , from which geometric information including strut length and pore shapes are extracted. The X-ray {mu}CT analysis allows comparison of the ideal geometric models to the actual geometric characteristics of the metal foam samples. The results reveal a high variability in ligament length, as well as features supporting the ideal geometry known as the Weaire-Phelan unit cell. The geometric findings provide information useful for improving current models of open-cell metal foam. Applications can range from predicting heat transfer or load failure to predicting liquid retention. Highlights: Black-Right-Pointing-Pointer Aluminum open-cell metal foams are geometrically classified Black-Right-Pointing-Pointer X-ray micro-computed tomography and specialized software are used to gather geometric data Black-Right-Pointing-Pointer The foams are shown to have a high variability in strut length Black-Right-Pointing-Pointer The Weaire-Phelan unit cell is shown to be a better representative of these foams.

  17. Imaging live cell in micro-liquid enclosure by X-ray laser diffraction

    PubMed Central

    Kimura, Takashi; Joti, Yasumasa; Shibuya, Akemi; Song, Changyong; Kim, Sangsoo; Tono, Kensuke; Yabashi, Makina; Tamakoshi, Masatada; Moriya, Toshiyuki; Oshima, Tairo; Ishikawa, Tetsuya; Bessho, Yoshitaka; Nishino, Yoshinori

    2014-01-01

    Emerging X-ray free-electron lasers with femtosecond pulse duration enable single-shot snapshot imaging almost free from sample damage by outrunning major radiation damage processes. In bioimaging, it is essential to keep the sample close to its natural state. Conventional high-resolution imaging, however, suffers from severe radiation damage that hinders live cell imaging. Here we present a method for capturing snapshots of live cells kept in a micro-liquid enclosure array by X-ray laser diffraction. We place living Microbacterium lacticum cells in an enclosure array and successively expose each enclosure to a single X-ray laser pulse from the SPring-8 Angstrom Compact Free-Electron Laser. The enclosure itself works as a guard slit and allows us to record a coherent diffraction pattern from a weakly-scattering submicrometre-sized cell with a clear fringe extending up to a 28-nm full-period resolution. The reconstructed image reveals living whole-cell structures without any staining, which helps advance understanding of intracellular phenomena. PMID:24394916

  18. 17.6%-Efficient radial junction solar cells using silicon nano/micro hybrid structures.

    PubMed

    Lee, Kangmin; Hwang, Inchan; Kim, Namwoo; Choi, Deokjae; Um, Han-Don; Kim, Seungchul; Seo, Kwanyong

    2016-08-14

    We developed a unique nano- and microwire hybrid structure by selectively modifying only the tops of microwires using metal-assisted chemical etching. The proposed nano/micro hybrid structure not only minimizes surface recombination but also absorbs 97% of incident light under AM 1.5G illumination, demonstrating outstanding light absorption compared to that of planar (59%) and microwire arrays (85%). The proposed hybrid solar cells with an area of 1 cm(2) exhibit power conversion efficiencies (Eff) of up to 17.6% under AM 1.5G illumination. In particular, the solar cells show a high short-circuit current density (Jsc) of 39.5 mA cm(-2) because of the high light-absorbing characteristics of the nanostructures. This corresponds to an approximately 61.5% and 16.5% increase in efficiency compared to that of a planar silicon solar cell (Eff = 10.9%) and a microwire solar cell (Eff = 15.1%), respectively. Therefore, we expect the proposed hybrid structure to become a foundational technology for the development of highly efficient radial junction solar cells. PMID:27405387

  19. Catalytic Molecular Imaging of MicroRNA in Living Cells by DNA-Programmed Nanoparticle Disassembly.

    PubMed

    He, Xuewen; Zeng, Tao; Li, Zhi; Wang, Ganglin; Ma, Nan

    2016-02-24

    Molecular imaging is an essential tool for disease diagnostics and treatment. Direct imaging of low-abundance nucleic acids in living cells remains challenging because of the relatively low sensitivity and insufficient signal-to-background ratio of conventional molecular imaging probes. Herein, we report a class of DNA-templated gold nanoparticle (GNP)-quantum dot (QD) assembly-based probes for catalytic imaging of cancer-related microRNAs (miRNA) in living cells with signal amplification capacity. We show that a single miRNA molecule could catalyze the disassembly of multiple QDs with the GNP through a DNA-programmed thermodynamically driven entropy gain process, yielding significantly amplified QD photoluminescence (PL) for miRNA imaging. By combining the robust PL of QDs with the catalytic amplification strategy, three orders of magnitude improvement in detection sensitivity is achieved in comparison with non-catalytic imaging probe, which enables facile and accurate differentiation between cancer cells and normal cells by miRNA imaging in living cells. PMID:26694689

  20. MicroRNA-224 Suppresses Colorectal Cancer Cell Migration by Targeting Cdc42

    PubMed Central

    Hsu, Han-Lin; Wu, Yu-Hua; Chen, William Tzu-Liang; Cheng, Ya-Wen

    2014-01-01

    The metastatic spread of tumor cells is the major risk factor affecting the clinical prognosis of colorectal cancer (CRC) patients. The metastatic phenotype can be modulated by dysregulating the synthesis of different structural and functional proteins of tumor cells. Micro(mi)RNAs are noncoding RNAs that recognize their cognate messenger (m)RNA targets by sequence-specific interactions with the 3′ untranslated region and are involved in the multistep process of CRC development. The objective of this study was to investigate the expression and biological roles of miR-224 in CRC. The miR-224 expression level was assessed by a quantitative real-time PCR in 79 CRC and 18 nontumor tissues. Expression levels of miR-224 in CRC tissues were significantly lower than those in nontumor tissues. Its expression level was associated with the mutation status of the APC gene. Ectopic expression of miR-224 suppressed the migratory ability of CRC cell line, but cell proliferation was less affected. Increased miR-224 diminished Cdc42 and SMAD4 expressions at both the protein and mRNA levels and inhibited the formation of actin filaments. Overall, this study indicated a role of miR-224 in negatively regulating CRC cell migration. The expression level of miR-224 may be a useful predictive biomarker for CRC progression. PMID:24817781

  1. Probing neural cell behaviors through micro-/nano-patterned chitosan substrates.

    PubMed

    Sung, Chun-Yen; Yang, Chung-Yao; Chen, Wen-Shiang; Wang, Yang-Kao; Yeh, J Andrew; Cheng, Chao-Min

    2015-12-01

    In this study, we describe the development of surface-modified chitosan substrates to examine topographically related Neuro-2a cell behaviors. Different functional groups can be modified on chitosan surfaces to probe Neuro-2a cell morphology. To prepare chitosan substrates with micro/nano-scaled features, we demonstrated an easy-to-handle method that combined photolithography, inductively coupled plasma reactive ion etching, Ag nanoparticle-assisted etching, and solution casting. The results show that Neuro-2a cells preferred to adhere to a flat chitosan surface rather than a nanotextured chitosan surface as evidenced by greater immobilization and differentiation, suggesting that surface topography is crucial for neural patterning. In addition, we developed chitosan substrates with different geometric patterns and flat region depth; this allowed us to re-arrange or re-pattern Neuro-2a cell colonies at desired locations. We found that a polarity-induced micropattern provided the most suitable surface pattern for promoting neural network formation on a chitosan substrate. The cellular polarity of single Neuro-2a cell spreading correlated to a diamond-like geometry and neurite outgrowth was induced from the corners toward the grooves of the structures. This study provide greater insight into neurobiology, including neurotransmitter screening, electrophysiological stimulation platforms, and biomedical engineering. PMID:26685015

  2. Flavin fluorescence lifetime imaging of living peripheral blood mononuclear cells on micro and nano-structured surfaces

    NASA Astrophysics Data System (ADS)

    Teplicky, T.; Horilova, J.; Bruncko, J.; Gladine, C.; Lajdova, I.; Mateasik, A.; Chorvat, D.; Marcek Chorvatova, A.

    2015-03-01

    Fabricated micro- and nano-structured surfaces were evaluated for use with living cells. Metabolic state was tested by means of endogenous flavin fluorescence of living peripheral blood mononuclear cells (PBMC) positioned on a coverslip, non-covered, or covered with micro- or nano-structured surfaces (OrmoComp polymer structures produced by 2-photon photopolymerisation, or Zinc Oxide (ZnO) layer fabricated by pulsed laser deposition). Confocal microscopy and Fluorescence Lifetime Imaging Microscopy (FLIM) were employed to gather flavin fluorescence lifetime images of living PBMC on structured surfaces. Gathered data are the first step towards monitoring of the live cell interaction with different micro/nano-structured surfaces and thus evaluate their potential applicability in the biomedical field.

  3. MicroRNA inhibition fine-tunes and provides robustness to the restriction point switch of the cell cycle.

    PubMed

    Del Rosario, Ricardo C H; Damasco, Joseph Ray Clarence G; Aguda, Baltazar D

    2016-01-01

    The restriction point marks a switch in G1 from growth factor-dependent to growth factor-independent progression of the cell cycle. The proper regulation of this switch is important for normal cell processes; aberrations could result in a number of diseases such as cancer, neurodegenerative disorders, stroke and myocardial infarction. To further understand the regulation of the restriction point, we extended a mathematical model of the Rb-E2F pathway to include members of the microRNA cluster miR-17-92. Our mathematical analysis shows that microRNAs play an essential role in fine-tuning and providing robustness to the switch. We also demonstrate how microRNA regulation can steer cells in or out of cancer states. PMID:27610602

  4. MicroRNA inhibition fine-tunes and provides robustness to the restriction point switch of the cell cycle

    PubMed Central

    del Rosario, Ricardo C. H.; Damasco, Joseph Ray Clarence G.; Aguda, Baltazar D.

    2016-01-01

    The restriction point marks a switch in G1 from growth factor-dependent to growth factor-independent progression of the cell cycle. The proper regulation of this switch is important for normal cell processes; aberrations could result in a number of diseases such as cancer, neurodegenerative disorders, stroke and myocardial infarction. To further understand the regulation of the restriction point, we extended a mathematical model of the Rb-E2F pathway to include members of the microRNA cluster miR-17-92. Our mathematical analysis shows that microRNAs play an essential role in fine-tuning and providing robustness to the switch. We also demonstrate how microRNA regulation can steer cells in or out of cancer states. PMID:27610602

  5. Improved Charge-Collection Efficiency in PCDTBT:PC71BM-Based Solar Cells via CS2 Solvent Vapor Annealing

    NASA Astrophysics Data System (ADS)

    Fang, Gang; Wu, Jiang; Fu, Ying-Ying; Meng, Bin; Xie, Zhi-Yuan; Guo, Shi-Jie

    2013-06-01

    Photo-generated charge collection is strongly correlated with the alignment and connectivity of the individual domains of donor and acceptor in bulk heterojunction polymer solar cells. It is found that CS2 vapor annealing on PCDTBT:PC71BM (1:4) blend effectively improves the hole-transport pathways of PCDTBT domains, which reduces accumulation of photo-generated charges and improves charge collection efficiency. The PCDTBT:PC71BM-based solar cells with the active layer subjected to CS2 vapor annealing demonstrate a high fill factor of 0.71-0.73 and a power conversion efficiency of 6.68%, about a 10% increase in comparison with the control cell.

  6. MicroRNA-222 regulates muscle alternative splicing through Rbm24 during differentiation of skeletal muscle cells.

    PubMed

    Cardinali, B; Cappella, M; Provenzano, C; Garcia-Manteiga, J M; Lazarevic, D; Cittaro, D; Martelli, F; Falcone, G

    2016-01-01

    A number of microRNAs have been shown to regulate skeletal muscle development and differentiation. MicroRNA-222 is downregulated during myogenic differentiation and its overexpression leads to alteration of muscle differentiation process and specialized structures. By using RNA-induced silencing complex (RISC) pulldown followed by RNA sequencing, combined with in silico microRNA target prediction, we have identified two new targets of microRNA-222 involved in the regulation of myogenic differentiation, Ahnak and Rbm24. Specifically, the RNA-binding protein Rbm24 is a major regulator of muscle-specific alternative splicing and its downregulation by microRNA-222 results in defective exon inclusion impairing the production of muscle-specific isoforms of Coro6, Fxr1 and NACA transcripts. Reconstitution of normal levels of Rbm24 in cells overexpressing microRNA-222 rescues muscle-specific splicing. In conclusion, we have identified a new function of microRNA-222 leading to alteration of myogenic differentiation at the level of alternative splicing, and we provide evidence that this effect is mediated by Rbm24 protein. PMID:26844700

  7. MicroRNA-222 regulates