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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. AMTEC vapor-vapor series connected cells

    NASA Astrophysics Data System (ADS)

    Underwood, Mark L.; Williams, Robert M.; Ryan, Margaret A.; Jeffries-Nakamura, Barbara; Oconnor, Dennis

    1993-01-01

    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.

  4. AMTEC vapor-vapor series connected cells

    NASA Astrophysics Data System (ADS)

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

    1995-08-01

    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.

  5. 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.

  6. Aluminum Nitride Micro-Channels Grown via Metal Organic Vapor Phase Epitaxy for MEMs Applications

    SciTech Connect

    Rodak, L.E.; Kuchibhatla, S.; Famouri, P.; Ting, L.; Korakakis, D.

    2008-01-01

    Aluminum nitride (AlN) is a promising material for a number of applications due to its temperature and chemical stability. Furthermore, AlN maintains its piezoelectric properties at higher temperatures than more commonly used materials, such as Lead Zirconate Titanate (PZT) [1, 2], making AlN attractive for high temperature micro and nanoelectromechanical (MEMs and NEMs) applications including, but not limited to, high temperature sensors and actuators, micro-channels for fuel cell applications, and micromechanical resonators. This work presents a novel AlN micro-channel fabrication technique using Metal Organic Vapor Phase Epitaxy (MOVPE). AlN easily nucleates on dielectric surfaces due to the large sticking coefficient and short diffusion length of the aluminum species resulting in a high quality polycrystalline growth on typical mask materials, such as silicon dioxide and silicon nitride [3,4]. The fabrication process introduced involves partially masking a substrate with a silicon dioxide striped pattern and then growing AlN via MOVPE simultaneously on the dielectric mask and exposed substrate. A buffered oxide etch is then used to remove the underlying silicon dioxide and leave a free standing AlN micro-channel. The width of the channel has been varied from 5 ìm to 110 ìm and the height of the air gap from 130 nm to 800 nm indicating the stability of the structure. Furthermore, this versatile process has been performed on (111) silicon, c-plane sapphire, and gallium nitride epilayers on sapphire substrates. Reflection High Energy Electron Diffraction (RHEED), Atomic Force Microscopy (AFM), and Raman measurements have been taken on channels grown on each substrate and indicate that the substrate is influencing the growth of the AlN micro-channels on the SiO2 sacrificial layer.

  7. 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.

  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.

  9. 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.

  10. 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.

  11. Vapor sensing with a natural photonic cell.

    PubMed

    Mouchet, Sébastien R; Tabarrant, Tijani; Lucas, Stéphane; Su, Bao-Lian; Vukusic, Pete; Deparis, Olivier

    2016-05-30

    Photonic structures encased by a permeable envelope give rise to iridescent blue color in the scales covering the male Hoplia coerulea beetle. This structure comprises a periodic porous multilayer. The color of these scales is known for changing from blue to green upon contact with water despite the presence of the envelope. This optical system has been referred to as a photonic cell due to the role of the envelope that mediates fluid exchanges with the surrounding environment. Following from previously studied liquid-induced changes in the color appearance of H. coerulea, we measured vapor-induced color changes in its appearance. This response to vapor exposure was marked by reflectance redshift and an increase in peak reflectance intensity. Different physico-chemical processes were investigated to explain the increase in reflectance intensity, a property not usually associated with vapor-induced optical signature changes. These simulations indicated the optical response arose from physisorption of a liquid film on the beetle scales followed by liquid penetration through the envelope and the filling of micropores within the body of the photonic structure. PMID:27410142

  12. An optical absorption cell with vapor cross flow.

    NASA Technical Reports Server (NTRS)

    Hendrickson, P. E.; Walls, W. L.; Broersma, S.

    1973-01-01

    Description of a water vapor cross flow system that simulates meteorological conditions and effectively curbs any disturbing effects of walls and vacuum connections in an optical absorption cell. Vapor equilibrium is established within 30 min. A 6.3 micron infrared beam traverses the pressure, temperature, and humidity controlled vapor column. The effect of these thermodynamic parameters can be examined.

  13. Characterization of Bioeffects on Endothelial Cells under Acoustic Droplet Vaporization.

    PubMed

    Seda, Robinson; Li, David S; Fowlkes, J Brian; Bull, Joseph L

    2015-12-01

    Gas embolotherapy is achieved by locally vaporizing microdroplets through acoustic droplet vaporization, which results in bubbles that are large enough to occlude blood flow directed to tumors. Endothelial cells, lining blood vessels, can be affected by these vaporization events, resulting in cell injury and cell death. An idealized monolayer of endothelial cells was subjected to acoustic droplet vaporization using a 3.5-MHz transducer and dodecafluoropentane droplets. Treatments included insonation pressures that varied from 2 to 8 MPa (rarefactional) and pulse lengths that varied from 4 to 16 input cycles. The bubble cloud generated was directly dependent on pressure, but not on pulse length. Cellular damage increased with increasing bubble cloud size, but was limited to the bubble cloud area. These results suggest that vaporization near the endothelium may impact the vessel wall, an effect that could be either deleterious or beneficial depending on the intended overall therapeutic application.

  14. 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.

  15. Measurement of the Rydberg ionization current in thermal vapor cells

    NASA Astrophysics Data System (ADS)

    Loew, Robert; Barredo, Daniel; Daschner, Renate; Kuebler, Harald; Ritter, Ralf; Pfau, Tilman

    2013-05-01

    Rydberg atoms confined in atomic vapor cells are promising candidates for the realization of single photon sources and quantum optical devices. To date, most information about the behavior of the Rydberg ensembles in thermal vapors has been extracted by absorptive measurements, e.g. EIT. However, to access directly quantities, like the population of the excited states, new methods are needed. In this task, the detection of the Rydberg ionization current provides a complementary and direct insight in the atomic processes. We show measurements of the Rydberg-ion current in thermal vapor cells equipped with field plates inside the vacuum. arXiv:1209.655.

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

    DOE PAGES

    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

  18. Thermal design of high temperature alkaline-earth vapor cells

    NASA Astrophysics Data System (ADS)

    Armstrong, Jordan L.; Lemke, Nathan D.; Martin, Kyle W.; Erickson, Christopher J.

    2016-03-01

    Europium doped calcium fluoride is a machinable and alkaline-earth resistant crystal that is suitable for constructing a calcium or strontium vapor cell. However, its heat capacity, emissivity, and high coefficient of thermal expansion make it challenging to achieve optically dense calcium vapors for laser spectroscopy on narrow linewidth transitions. We discuss a low size, weight and power heating package that is under development at the Air Force Research Laboratory.

  19. MicroRNA-mediated somatic cell reprogramming.

    PubMed

    Kuo, Chih-Hao; Ying, Shao-Yao

    2013-02-01

    Since the first report of induced pluripotent stem cells (iPSCs) using somatic cell nuclear transfer (SCNT), much focus has been placed on iPSCs due to their great therapeutic potential for diseases such as abnormal development, degenerative disorders, and even cancers. Subsequently, Takahashi and Yamanaka took a novel approach by using four defined transcription factors to generate iPSCs in mice and human fibroblast cells. Scientists have since been trying to refine or develop better approaches to reprogramming, either by using different combinations of transcription factors or delivery methods. However, recent reports showed that the microRNA expression pattern plays a crucial role in somatic cell reprogramming and ectopic introduction of embryonic stem cell-specific microRNAs revert cells back to an ESC-like state, although, the exact mechanism underlying this effect remains unclear. This review describes recent work that has focused on microRNA-mediated approaches to somatic cell reprogramming as well as some of the pros and cons to these approaches and a possible mechanism of action. Based on the pivotal role of microRNAs in embryogenesis and somatic cell reprogramming, studies in this area must continue in order to gain a better understanding of the role of microRNAs in stem cells regulation and activity. PMID:22961769

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  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. 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.

  6. 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.

  7. Pressure sensitivity of the vapor-cell atomic clock.

    PubMed

    Iyanu, Gebriel; Wang, He; Camparo, James

    2009-06-01

    Although atomic clocks have very low levels of frequency instability, they are nonetheless sensitive (albeit slightly) to various environmental parameters, including temperature, power supply voltage, and dc magnetic fields. In the terrestrial environment, however, atmospheric pressure (i.e., the air's molecular density) is not generally included in this list, because the air's density variations near the surface of the earth will typically have a negligible effect on the clock's performance. The situation is different, however, for clocks onboard satellites like Galileo, where manufacturing and testing are done at atmospheric pressure, while operation is in vacuum. The pressure sensitivity of atomic clocks, in particular vapor-cell atomic clocks, can therefore be of significance. Here, we discuss some of the ways in which changes in atmospheric pressure affect vapor-cell atomic clocks, and we demonstrate that, for one device, the pressure-sensitivity traces back to a pressure-induced change in the temperature of the clock's filter and resonance cells.

  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. 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.

  10. 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.

  11. Femtotesla atomic magnetometry in a microfabricated vapor cell.

    PubMed

    Griffith, W Clark; Knappe, Svenja; Kitching, John

    2010-12-20

    We describe an optically pumped 87Rb magnetometer with 5 fT/Hz(1/2) sensitivity when operated in the spin-exchange relaxation free (SERF) regime. The magnetometer uses a microfabricated vapor cell consisting of a cavity etched in a 1 mm thick silicon wafer with anodically bonded Pyrex windows. The measurement volume of the magnetometer is 1 mm3, defined by the overlap region of a circularly polarized pump laser and a linearly polarized probe laser, both operated near 795 nm. Sensitivity limitations unique to the use of microfabricated cells are discussed.

  12. 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.

  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

    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.

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. 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

  20. 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.

  1. Micro/nano-fabrication technologies for cell biology.

    PubMed

    Qian, Tongcheng; Wang, Yingxiao

    2010-10-01

    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.

  2. 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.

  3. Modulation transfer spectroscopy in a lithium atomic vapor cell.

    PubMed

    Sun, Dali; Zhou, Chao; Zhou, Lin; Wang, Jin; Zhan, Mingsheng

    2016-05-16

    We have investigated modulation transfer spectroscopy of D2 transitions of 7Li atoms in a vapor cell. The role of the intensity of the probe beam in the spectrum is important, we have seen unique characteristics of the signal in the crossover peak. In order to find the best signal for laser locking, the slope and frequency offset of the zero-crossing signal are determined. The dependence of the modulation transfer spectra on polarizations of pump and probe beam is demonstrated. The residual amplitude modulation in the system is also considered, and the distortion of the spectra due to the modulation is analyzed. It was found that the crossover peak is more suitable for frequency stabilization due to its better residual amplitude modulation compensation.

  4. Modulation transfer spectroscopy in a lithium atomic vapor cell.

    PubMed

    Sun, Dali; Zhou, Chao; Zhou, Lin; Wang, Jin; Zhan, Mingsheng

    2016-05-16

    We have investigated modulation transfer spectroscopy of D2 transitions of 7Li atoms in a vapor cell. The role of the intensity of the probe beam in the spectrum is important, we have seen unique characteristics of the signal in the crossover peak. In order to find the best signal for laser locking, the slope and frequency offset of the zero-crossing signal are determined. The dependence of the modulation transfer spectra on polarizations of pump and probe beam is demonstrated. The residual amplitude modulation in the system is also considered, and the distortion of the spectra due to the modulation is analyzed. It was found that the crossover peak is more suitable for frequency stabilization due to its better residual amplitude modulation compensation. PMID:27409886

  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. A hybrid sequential deposition fabrication technique for micro fuel cells

    NASA Astrophysics Data System (ADS)

    Stanley, Kevin G.; Czyzewska, Eva K.; Vanderhoek, Tom P. K.; Fan, Lilian L. Y.; Abel, Keith A.; Wu, Q. M. Jonathan; Parameswaran, M. Ash

    2005-10-01

    Micro fuel cell systems have elicited significant interest due to their promise for instantly rechargeable, longer duration and portable power. Most micro fuel cell systems are either built as miniaturized plate-and-frame or silicon-based microelectromechanical systems (MEMS). Plate-and-frame systems are difficult to fabricate smaller than 20 cm3. Existing micro fuel cell designs cannot meet the cost, scale and power requirements of some portable power markets. Traditional MEMS scaling advantages do not apply to fuel cells because the minimum area for the fuel cell is fixed by the catalyst area required for a given power output, and minimum volume set by mass transport limitations. We have developed a new hybrid technique that borrows from both micro and macro machining techniques to create fuel cells in the 1-20 cm3 range, suitable for cell phones, PDAs and smaller devices.

  7. MicroRNAs in neural cell development and brain diseases.

    PubMed

    Feng, Wei; Feng, Yue

    2011-12-01

    MicroRNAs play important roles in post-transcriptional regulation of gene expression by inhibiting protein translation and/or promoting mRNA degradation. Importantly, biogenesis of microRNAs displays specific temporal and spatial profiles in distinct cell and tissue types and hence affects a broad spectrum of biological functions in normal cell growth and tumor development. Recent discoveries have revealed sophisticated mechanisms that control microRNA production and homeostasis in response to developmental and extracellular signals. Moreover, a link between dysregulation of microRNAs and human brain disorders has become increasingly evident. In this review, we focus on recent advances in understanding the regulation of microRNA biogenesis and function in neuronal and glial development in the mammalian brain, and dysregulation of the microRNA pathway in neurodevelopmental and neurodegenerative diseases.

  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

    2011-01-11

    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.

  9. Shadow masked organometallic vapor phase epitaxy for advanced micro-optical structures

    NASA Astrophysics Data System (ADS)

    Peake, Gregory Merwin

    2000-12-01

    This thesis presents novel techniques and applications of nonplanar chemical vapor deposition (CVD) for optoelectronic materials and devices. Specifically, nonplanar organometallic vapor phase epitaxy (OMVPE) employing a shadow mask has been developed for the fabrication of integrated optoelectronic structures. Shadow masked OMVPE (SM-OMVPE) is currently the only technique known to produce thick, nonplanar layers of single crystal material without macroscopic faceting. By the use of SM-OMVPE, various microlenses, micromirrors and novel devices have been designed fabricated and tested. Shadow masked microlenses with record short focal lengths have been produced. High quality microlens arrays with accurate control of lens diameter, sagitta, focal length, astigmatism and position have been designed, fabricated and tested. The author has shown that precise three-dimensional control during crystal growth can be employed to construct useful optoelectronic structures in a reproducible manner. This work also presents novel techniques for the fabrication of shadow masks. A high aluminum- concentration spacer layer and chemical recipes for the removal of epitaxial shadow masks are reported. In addition, the first reusable shadow mask constructed by reactive ion etching has been utilized for the growth of shadow masked structures. Direct fusion wafer bonding of silicon shadow masks was first developed by the author and has proven to be a robust, clean and reliable technique for mask placement. The application of shadow masked growth to vertical cavity semiconductor lasers (VCSELs) was initiated in this work. Microlenses were designed for top-emitting VCSELs to provide focusing of the output beam and these designs are currently being fabricated at Sandia National Laboratories. Furthermore, by introducing curvature to the distributed Bragg reflector (DBR) mirrors, a high power single mode VCSEL has been designed. The author has grown the first concentrically

  10. A Methanol Steam Reforming Micro Reactor for Proton Exchange Membrane Micro Fuel Cell System

    SciTech Connect

    Park, H G; Piggott, W T; Chung, J; Morse, J D; Havstad, M; Grigoropoulos, C P; Greif, R; Benett, W; Sopchak, D; Upadhye, R

    2003-07-28

    The heat, mass and momentum transfer from a fuel reforming packed bed to a surrounding silicon wafer has been simulated. Modeling showed quantitatively reasonable agreement with experimental data for fuel conversion efficiency, hydrogen production rate, outlet methanol mole fraction and outlet steam mole fraction. The variation in fuel conversion efficiency with the micro reformer thermal isolation can be used to optimize fuel-processing conditions for micro PEM fuel cells.

  11. 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.

  12. Sickle cell microRNAs inhibit the malaria parasite.

    PubMed

    Duraisingh, Manoj T; Lodish, Harvey F

    2012-08-16

    Sickle cell hemoglobin conveys resistance to malaria. In this issue of Cell Host & Microbe, LaMonte et al. (2012) demonstrate a surprising mechanism for this innate immunity. A microRNA enriched in sickle red blood cells is translocated into the parasite, incorporated covalently into P. falciparum mRNAs and inhibits parasite growth.

  13. MicroRNAs targeting prostate cancer stem cells

    PubMed Central

    Fang, Yu-Xiang; Chang, Yun-Li

    2015-01-01

    Prostate cancer is a frequently diagnosed cancer in males with high mortality in the world. As a heterogeneous tissue, the tumor mass contains a subpopulation that is called as cancer stem cells and displays stem-like properties such as self-renewal, epithelial–mesenchymal transition, metastasis, and drug resistance. Cancer stem cells have been identified in variant tumors and shown to be regulated by various molecules including microRNAs. MicroRNAs are a class of small non-coding RNAs, which can influence tumorigenesis via different mechanisms. In this review, we focus on the functions of microRNAs on regulating the stemness of prostate cancer stem cells with different mechanisms and propose the potential roles of microRNAs in prostate cancer therapy. PMID:25966983

  14. 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

  15. 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.

  16. 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.

  17. MicroRNAs: key regulators of stem cells.

    PubMed

    Gangaraju, Vamsi K; Lin, Haifan

    2009-02-01

    The hallmark of a stem cell is its ability to self-renew and to produce numerous differentiated cells. This unique property is controlled by dynamic interplays between extrinsic signalling, epigenetic, transcriptional and post-transcriptional regulations. Recent research indicates that microRNAs (miRNAs) have an important role in regulating stem cell self-renewal and differentiation by repressing the translation of selected mRNAs in stem cells and differentiating daughter cells. Such a role has been shown in embryonic stem cells, germline stem cells and various somatic tissue stem cells. These findings reveal a new dimension of gene regulation in controlling stem cell fate and behaviour. PMID:19165214

  18. 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

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Theoretical study on temperature features of a sealed cesium vapor cell pumped by laser diodes.

    PubMed

    Zhang, Wei; Wang, You; Cai, He; Xue, Liangping; Han, Juhong; Wang, Hongyuan; Liao, Zhiye

    2014-07-01

    The diode-pumped alkali laser (DPAL) is a new type of laser source which has been widely studied in the recent years. The temperature distribution of a sealed vapor cell, which is the crucial component in a DPAL system, produces an important effect on the output performance of a DPAL. In this paper, the strict solution of the heat conduction equation for a cesium vapor cell is obtained by using a finite difference procedure. The temperature distribution of a dummy open cell is first analyzed, and then the temperature distributions of two independent windows, regarded as the boundary conditions of solving a sealed cell, are evaluated in detail. By combining the results of the two steps together, we finally acquire the temperature distribution of a real sealed cesium vapor cell. The results reveal that the temperature gradients on both radial and longitudinal directions change with the pump power, cell radius, and absorption coefficient when the sealed cesium vapor cell is heated or pumped with the laser diodes. The conclusions are helpful for accurately evaluating the output characteristics of a DPAL.

  6. 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.

  7. High efficiency micro solar cells integrated with lens array

    NASA Astrophysics Data System (ADS)

    Fidaner, Onur; Suarez, Ferran A.; Wiemer, Michael; Sabnis, Vijit A.; Asano, Tetsuya; Itou, Akihiro; Inoue, Daijiro; Hayashi, Nobuhiko; Arase, Hidekazu; Matsushita, Akio; Nakagawa, Tohru

    2014-03-01

    We demonstrate high efficiency triple junction solar cells with submillimeter dimensions in an all-back-contact architecture. 550 × 550 μm2 cells flash at 41.3% efficiency under the air mass 1.5 direct normal spectrum at 50 W/cm2 at 25 °C. Compared to standard size production cells, the micro cells have reduced performance at 1-sun due to perimeter recombination, but the performance gap closes at higher concentrations. Micro cells integrated with lens arrays were tested on-sun with an efficiency of 34.7%. All-back-contact architecture and submillimeter dimensions are advantageous for module integration and heat dissipation, allowing for high-performance, compact, lightweight, and cost-effective concentrated photovoltaic modules.

  8. 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.

  9. 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.

  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. 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.

  12. MicroRNAs: Modulators of Cell Identity, and their Applications in Tissue Engineering

    PubMed Central

    Ribeiro, Amanda O; Schoof, Cláudia R. G; Izzotti, Alberto; Pereira, Lygia V; Vasques, Luciana R

    2014-01-01

    MicroRNAs post-transcriptionally regulate the expression of approximately 60% of the mammalian genes, and have an important role in maintaining the differentiated state of somatic cells through the expression of unique tissue-specific microRNA sets. Likewise, the stemness of pluripotent cells is also sustained by embryonic stem cell-enriched microRNAs, which regulate genes involved in cell cycle, cell signaling and epigenetics, among others. Thus, microRNAs work as modulator molecules that ensure the appropriate expression profile of each cell type. Manipulation of microRNA expression might determine the cell fate. Indeed, microRNA-mediated reprogramming can change the differentiated status of somatic cells towards stemness or, conversely, microRNAs can also transform stem- into differentiated-cells both in vitro and in vivo. In this Review, we outline what is currently known in this field, focusing on the applications of microRNA in tissue engineering. PMID:25069512

  13. 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.

  14. 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

  15. 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.

  16. 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

  17. 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.

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

    PubMed

    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.

  20. 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.

  1. Tolerant chalcogenide cathodes of membraneless micro fuel cells.

    PubMed

    Gago, Aldo Saul; Gochi-Ponce, Yadira; Feng, Yong-Jun; Esquivel, Juan Pablo; Sabaté, Neus; Santander, Joaquin; Alonso-Vante, Nicolas

    2012-08-01

    The most critical issues to overcome in micro direct methanol fuel cells (μDMFCs) are the lack of tolerance of the platinum cathode and fuel crossover through the polymer membrane. Thus, two novel tolerant cathodes of a membraneless microlaminar-flow fuel cell (μLFFC), Pt(x)S(y) and CoSe(2), were developed. The multichannel structure of the system was microfabricated in SU-8 polymer. A commercial platinum cathode served for comparison. When using 5 M CH(3)OH as the fuel, maximum power densities of 6.5, 4, and 0.23 mW cm(-2) were achieved for the μLFFC with Pt, Pt(x)S(y), and CoSe(2) cathodes, respectively. The Pt(x)S(y) cathode outperformed Pt in the same fuel cell when using CH(3)OH at concentrations above 10 M. In a situation where fuel crossover is 100 %, that is, mixing the fuel with the reactant, the maximum power density of the micro fuel cell with Pt decreased by 80 %. However, for Pt(x)S(y) this decrease corresponded to 35 % and for CoSe(2) there was no change in performance. This result is the consequence of the high tolerance of the chalcogenide-based cathodes. When using 10 M HCOOH and a palladium-based anode, the μLFFC with a CoSe(2) cathode achieved a maxiumum power density of 1.04 mW cm(-2). This micro fuel cell does not contain either Nafion membrane or platinum. We report, for the first time, the evaluation of Pt(x)S(y)- and CoSe(2)-based cathodes in membraneless micro fuel cells. The results suggest the development of a novel system that is not size restricted and its operation is mainly based on the selectivity of its electrodes.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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

  8. Micro-organism and cell viability on antimicrobially modified titanium.

    PubMed

    Omori, S; Shibata, Y; Arimoto, T; Igarashi, T; Baba, K; Miyazaki, T

    2009-10-01

    When titanium is anodized by discharge in NaCl solution, both antimicrobial activity and osteoconductivity are conferred. The viability of adherent micro-organisms and cells on antimicrobial titanium remains uncertain. We hypothesized that a thin peroxidation barrier would efficiently destroy adherent bacteria, whereas adherent osteoblastic cells would be viable, since these cells adhere to the surface indirectly though serum proteins. The efficacy of antimicrobial titanium appears to be based on peroxidation, since peroxidation products were detected in parallel with the destruction of bacterial cell-surface structures. The peroxidation effect of antimicrobial titanium was confined to the surface within narrow limits. The viability of osteoblastic cells on the surface was strongly dependent on the presence of serum protein, whereas that of adherent Streptococcus mutans was not affected by the presence of serum proteins. Therefore, differences in the adherent systems used by bacteria and osteoblastic cells are important determinants of their viability on antimicrobial titanium.

  9. 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.

  10. Atomic vapor cells for chip-scale atomic clocks with improved long-term frequency stability.

    PubMed

    Knappe, S; Gerginov, V; Schwindt, P D D; Shah, V; Robinson, H G; Hollberg, L; Kitching, J

    2005-09-15

    A novel technique for microfabricating alkali atom vapor cells is described in which alkali atoms are evaporated into a micromachined cell cavity through a glass nozzle. A cell of interior volume 1 mm3, containing 87Rb and a buffer gas, was made in this way and integrated into an atomic clock based on coherent population trapping. A fractional frequency instability of 6 x 10(-12) at 1000 s of integration was measured. The long-term drift of the F=1, mF=0-->F=2, mF=0 hyperfine frequency of atoms in these cells is below 5 x 10(-11)/day.

  11. 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

  12. 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

  13. Conical evaporator and liquid-return wick model for vapor anode, multi-tube AMTEC cells

    NASA Astrophysics Data System (ADS)

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

    2000-01-01

    A detailed, 2-D thermal-hydraulic model for conical and flat evaporators and the liquid sodium return artery in PX-type AMTEC cells was developed, which predicts incipient dryout at the evaporator wick surface. Results obtained at fixed hot and cold side temperatures showed that the flat evaporator provided a slightly lower vapor pressure, but reached the capillary limit at higher temperature. The loss of performance due to partial recondensation over up to 20% of the wick surface of the deep conical evaporators was offset by the larger surface area available for evaporation, providing a slightly higher vapor pressure. Model results matched the PX-3A cell's experimental data of electrical power output, but the predicted temperature of the cell's conical evaporator was consistently ~50 K above measurements. A preliminary analysis indicated that sodium vapor leakage in the cell (through microcracks in the BASE tubes' walls or brazes) may explain the difference between predicted and measured evaporator temperatures in PX-3A. .

  14. 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.

  15. 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.

  16. Dual-axis vapor cell for simultaneous laser frequency stabilization on disparate optical transitions

    SciTech Connect

    Jayakumar, Anupriya Plotkin-Swing, Benjamin; Jamison, Alan O.; Gupta, Subhadeep

    2015-07-15

    We have developed a dual-axis ytterbium (Yb) vapor cell and used it to simultaneously address the two laser cooling transitions in Yb at wavelengths 399 nm and 556 nm, featuring the disparate linewidths of 2π × 29 MHz and 2π × 182 KHz, respectively. By utilizing different optical paths for the two wavelengths, we simultaneously obtain comparable optical densities suitable for saturated absorption spectroscopy for both the transitions and keep both the lasers frequency stabilized over several hours. We demonstrate that by appropriate control of the cell temperature profile, two atomic transitions differing in relative strength across a large range of over three orders of magnitude can be simultaneously addressed, making the device adaptable to a variety of spectroscopic needs. We also show that our observations can be understood with a simple theoretical model of the Yb vapor.

  17. 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.

  18. 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

  19. 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

  20. 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

  1. 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.

  2. 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

  3. 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

  4. Regulation of Stem Cell Populations by microRNAs

    PubMed Central

    Mathieu, Julie

    2014-01-01

    miRNAs are small non-coding RNAs that have emerged as crucial post-transcriptional regulators of gene expression. They are key players in various critical cellular processes such as proliferation, cell cycle progression, apoptosis and differentiation. Self-renewal capacity and differentiation potential are hallmarks of stem cells. The switch between self-renewal and differentiation requires rapid widespread changes in gene expression. Since miRNAs can repress the translation of many mRNA targets, they are good candidates to regulate cell fates. In the past few years, miRNAs have appeared as important new actors in stem cell development by regulating differentiation and maintenance of stem cells. In this chapter we will focus on the role of miRNAs in various stem cell populations. After an introduction on microRNA biogenesis, we will review the recent knowledge on miRNA expression and function in pluripotent cells and during the acquisition of stem cell fate. We will then brie fly examine the role of miRNAs in adult and cancer stem cells. PMID:23696365

  5. MicroRNA profiling of diverse endothelial cell types

    PubMed Central

    2011-01-01

    Background MicroRNAs are ~22-nt long regulatory RNAs that serve as critical modulators of post-transcriptional gene regulation. The diversity of miRNAs in endothelial cells (ECs) and the relationship of this diversity to epithelial and hematologic cells is unknown. We investigated the baseline miRNA signature of human ECs cultured from the aorta (HAEC), coronary artery (HCEC), umbilical vein (HUVEC), pulmonary artery (HPAEC), pulmonary microvasculature (HPMVEC), dermal microvasculature (HDMVEC), and brain microvasculature (HBMVEC) to understand the diversity of miRNA expression in ECs. Results We identified 166 expressed miRNAs, of which 3 miRNAs (miR-99b, miR-20b and let-7b) differed significantly between EC types and predicted EC clustering. We confirmed the significance of these miRNAs by RT-PCR analysis and in a second data set by Sylamer analysis. We found wide diversity of miRNAs between endothelial, epithelial and hematologic cells with 99 miRNAs shared across cell types and 31 miRNAs unique to ECs. We show polycistronic miRNA chromosomal clusters have common expression levels within a given cell type. Conclusions EC miRNA expression levels are generally consistent across EC types. Three microRNAs were variable within the dataset indicating potential regulatory changes that could impact on EC phenotypic differences. MiRNA expression in endothelial, epithelial and hematologic cells differentiate these cell types. This data establishes a valuable resource characterizing the diverse miRNA signature of ECs. PMID:22047531

  6. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    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 × 10-9/K in fractional unit. A hyperfine population lifetime, T1, and a microwave coherence lifetime, T2, 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.

  8. [Tumor Cells and Micro-environment in Brain Metastases].

    PubMed

    Zhong, Wen; Hu, Chengping

    2016-09-20

    Improvements in survival and quality of life of patients with lung cancer had been achieved due to the progression of early diagnosis and precision medicine at recent years, however, until now, treatments targeted at lesions in central nervous system are far from satisfying, thus threatening livelihood of patients involved. After all, in the issue of prophylaxis and therapeutics of brain metastases, it is crucial to learn about the biological behavior of tumor cells in brain metastases and its mechanism underlying, and the hypothesis "seed and soil", that is, tumor cells would generate series of adaptive changes to fit in the new environment, is liable to help explain this process well. In this assay, we reviewed documents concerning tumor cells, brain micro-environments and their interactions in brain metastases, aiming to provide novel insight into the treatments of brain metastases. PMID:27666556

  9. 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

  10. Novel photochemical vapor deposition reactor for amorphous silicon solar cell deposition

    NASA Astrophysics Data System (ADS)

    Rocheleau, Richard E.; Hegedus, Steven S.; Buchanan, Wayne A.; Jackson, Scott C.

    1987-07-01

    A novel photochemical vapor deposition (photo-CVD) reactor having a flexible ultraviolet-transparent Teflon curtain and a secondary gas flow to eliminate deposition on the window has been used to deposit amorphous silicon films and p-i-n solar cells. The background levels of atmospheric contaminants (H2O, CO2, N2) depend strongly on the vacuum procedures but not on the presence of a Teflon curtain in the reactor. Intrinsic films with a midgap density of states of 3×1015 eV-1 cm-3 and all-photo-CVD pin solar cells with efficiencies of 8.5% have been deposited.

  11. 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.

  12. 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.

  13. Analysis of advanced vapor source for cadmium telluride solar cell manufacturing

    NASA Astrophysics Data System (ADS)

    Khetani, Tejas Harshadkumar

    A thin film CdS/CdTe solar cell manufacturing line has been developed in the Materials Engineering Laboratory at Colorado State University. The original design incorporated infrared lamps for heating the vapor source. This system has been redesigned to improve the energy efficiency of the system, allow co-sublimation and allow longer run time before the sources have to be replenished. The advanced vapor source incorporates conduction heating with heating elements embedded in graphite. The advanced vapor source was modeled by computational fluid dynamics (CFD). From these models, the required maximum operating temperature of the element was determined to be 720 C for the processing of CdS/CdTe solar cells. Nichrome and Kanthal A1 were primarily selected for this application at temperature of 720 °C in vacuum with oxygen partial pressure. Research on oxidation effects and life due to oxidation as well as creep deformation was done, and Nichrome was found more suitable for this application. A study of the life of the Nichrome heating elements in this application was conducted and the estimate of life is approximately 1900 years for repeated on-off application. This is many orders of magnitude higher than the life of infrared heat lamps. Ceramic cement based on aluminum oxide (Resbond 920) is used for bonding the elements to the graphite. Thermodynamic calculations showed that this cement is inert to the heating element. An earlier design of the advanced source encountered failure of the element. The failed element was studies by scanning electron microscopy and the failure was attributed to loss of adhesion between the graphite and the ceramic element. The design has been modified and the advanced vapor source is currently in operation.

  14. Initiated chemical vapor deposition of thermoresponsive poly(N-vinylcaprolactam) thin films for cell sheet engineering.

    PubMed

    Lee, Bora; Jiao, Alex; Yu, Seungjung; You, Jae Bem; Kim, Deok-Ho; Im, Sung Gap

    2013-08-01

    Poly(N-vinylcaprolactam) (PNVCL) is a thermoresponsive polymer known to be nontoxic, water soluble and biocompatible. Here, PNVCL homopolymer was successfully synthesized for the first time by use of a one-step vapor-phase process, termed initiated chemical vapor deposition (iCVD). Fourier transform infrared spectroscopy results showed that radical polymerization took place from N-vinylcaprolactam monomers without damaging the functional caprolactam ring. A sharp lower critical solution temperature transition was observed at 31°C from the iCVD poly(N-vinylcaprolactam) (PNVCL) film. The thermoresponsive PNVCL surface exhibited a hydrophilic/hydrophobic alteration with external temperature change, which enabled the thermally modulated attachment and detachment of cells. The conformal coverage of PNVCL film on various substrates with complex topography, including fabrics and nanopatterns, was successfully demonstrated, which can further be utilized to fabricate cell sheets with aligned cell morphology. The advantage of this system is that cells cultured on such thermoresponsive surfaces could be recovered as an intact cell sheet by simply lowering the temperature, eliminating the need for conventional enzymatic treatments.

  15. MicroRNAs and mesenchymal stem cells: hope for pulmonary hypertension

    PubMed Central

    Zhu, Zhaowei; Fang, Zhenfei; Hu, Xinqun; Zhou, Shenghua

    2015-01-01

    Pulmonary hypertension is a devastating and refractory disease and there is no cure for this disease. Recently, microRNAs and mesenchymal stem cells emerged as novel methods to treat pulmonary hypertension. More than 20 kinds of microRNAs may participate in the process of pulmonary hypertension. It seems microRNAs or mesenchymal stem cells can ameliorate some symptoms of pulmonary hypertension in animals and even improve heart and lung function during pulmonary hypertension. Nevertheless, the relationship between mesenchymal stem cells, microRNAs and pulmonary hypertension is not clear. And the mechanisms underlying their function still need to be investigated. In this study we review the recent findings in mesenchymal stem cells - and microRNAs-based pulmonary hypertension treatment, focusing on the potential role of microRNAs regulated mesenchymal stem cells in pulmonary hypertension and the role of exosomes between mesenchymal stem cells and pulmonary hypertension. PMID:26313730

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

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

    DOE PAGES

    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

  2. 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.

  3. 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.

  4. MicroRNA-218, microRNA-191*, microRNA-3070a and microRNA-33 are responsive to mechanical strain exerted on osteoblastic cells.

    PubMed

    Guo, Yong; Wang, Yang; Liu, Yinqin; Liu, Yongming; Zeng, Qiangcheng; Zhao, Yumin; Zhang, Xinchang; Zhang, Xizheng

    2015-08-01

    MicroRNA (miRNA) is an important regulator of cell differentiation and function. Mechanical strain is important in the growth and differentiation of osteoblasts. Therefore, mechanresponsive miRNA may be important in the response of osteoblasts to mechanical strain. The purpose of the present study was to select and identify the mechanoresponsive miRNAs of osteoblasts. Mouse osteoblastic MC3T3-E1 cells were cultured in cell culture dishes and stimulated with a mechanical tensile strain of 2,50 με at 0.5 Hz, and the activity of alkaline phosphatase (ALP), mRNA levels of ALP, osteocalcin (OCN), and collagen type I (Col I), and protein levels of bone morphogenetic proteins (BMPs) in the cell culture medium were assayed. Following miRNA microarray and reverse transcription-quantitative polymerase chain reaction analyses, differentially expressed miRNAs in the mechanically strained cells and unstrained cells were selected and identified. Using bioinformatics analysis, the target genes of the miRNAs were then predicted. The results revealed that the mechanical strain of 2,500 με increased the activity of ALP, the mRNA levels of ALP, OCN and Col I, and the protein levels of bone morphogenetic protein(BMP)-2 and BMP-4 Continuous mechanical stimulation for 8 h had the most marked stimulant effects. miR-218, miR-191*, miR-3070a and miR-33 were identified as differentially expressed miRNAs in the mechanically strained MC3T3-E1 cells. Certain target genes of these four miRNAs were involved in osteoblastic differentiation. These findings indicated that a mechanical strain of 2,500 με, particularly for a period of 8 h, promoted osteoblastic differentiation, and the four mechanoresponsive miRNAs identified may be a potential regulator of osteoblastic differentiation and their response to mechanical strain.

  5. Vapor of Volatile Oils from Litsea cubeba Seed Induces Apoptosis and Causes Cell Cycle Arrest in Lung Cancer Cells

    PubMed Central

    Seal, Soma; Chatterjee, Priyajit; Bhattacharya, Sushmita; Pal, Durba; Dasgupta, Suman; Kundu, Rakesh; Mukherjee, Sandip; Bhattacharya, Shelley; Bhuyan, Mantu; Bhattacharyya, Pranab R.; Baishya, Gakul; Barua, Nabin C.; Baruah, Pranab K.; Rao, Paruchuri G.; Bhattacharya, Samir

    2012-01-01

    Non-small cell lung carcinoma (NSCLC) is a major killer in cancer related human death. Its therapeutic intervention requires superior efficient molecule(s) as it often becomes resistant to present chemotherapy options. Here we report that vapor of volatile oil compounds obtained from Litsea cubeba seeds killed human NSCLC cells, A549, through the induction of apoptosis and cell cycle arrest. Vapor generated from the combined oils (VCO) deactivated Akt, a key player in cancer cell survival and proliferation. Interestingly VCO dephosphorylated Akt at both Ser473 and Thr308; through the suppression of mTOR and pPDK1 respectively. As a consequence of this, diminished phosphorylation of Bad occurred along with the decreased Bcl-xL expression. This subsequently enhanced Bax levels permitting the release of mitochondrial cytochrome c into the cytosol which concomitantly activated caspase 9 and caspase 3 resulting apoptotic cell death. Impairment of Akt activation by VCO also deactivated Mdm2 that effected overexpression of p53 which in turn upregulated p21 expression. This causes enhanced p21 binding to cyclin D1 that halted G1 to S phase progression. Taken together, VCO produces two prong effects on lung cancer cells, it induces apoptosis and blocked cancer cell proliferation, both occurred due to the deactivation of Akt. In addition, it has another crucial advantage: VCO could be directly delivered to lung cancer tissue through inhalation. PMID:23091605

  6. Perforated hollow core waveguides for Alkali Vapor-cells and Slow Light Devices

    NASA Astrophysics Data System (ADS)

    Giraud-Carrier, Matthieu C.

    The focus of this work is the integration of alkali vapor atomic vapor cells into common silicon wafer microfabrication processes. Such integrated platforms enable the study of quantum coherence effects such as electromagnetically induced transparency, which can in turn be used to demonstrate slow light. Slow and stopped light devices have applications in the optical communications and quantum computing fields. This project uses hollow core anti-resonant reflecting optical waveguides (ARROWs) to build such slow light devices. An explanation of light-matter interactions and the physics of slow light is first provided, as well as a detailed overview of the fabrication process. Following the discovery of a vapor transport issue, a custom capillary-based testing platform is developed to quantify the effect of confinement, temperature, and wall coatings on rubidium transport. A mathematical model is derived from the experimental results and predicts long transport times. A new design methodology is presented that addresses the transport problem by increasing the number of rubidium entry points. This design also improves chip durability and decreases environmental susceptibility through the use of a single copper reservoir and buried channel waveguides (BCWs). New chips are successfully fabricated, loaded, and monitored for rubidium spectra. Absorption is observed in several chips and absorption peaks depths in excess of 10% are reported. The chip lifetime remains comparable to previous designs. This new design can be expanded to a multi-core platform suitable for slow and stopped light experimentation. Keywords: Matthieu Giraud-Carrier, Aaron Hawkins, microfabrication, spectroscopy, slow light, stopped light, EIT, rubidium, diffusion, vapor transport, microfabrication, ARROW, light-matter interactions, waveguide.

  7. 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. PMID:27588118

  8. 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}

  9. 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.

  10. Experimental and theoretical study of the vapor-cell Zeeman optical trap

    NASA Astrophysics Data System (ADS)

    Lindquist, K.; Stephens, M.; Wieman, C.

    1992-10-01

    We present an experimental study of the number and density of trapped atoms in a vapor-cell Zeeman optical trap. We have investigated how the number (and therefore the capture rate) and density change with the trapping laser's beam diameter, intensity, and detuning and with the magnetic-field gradient of the trap. We have developed a quasi-one-dimensional numerical model that accurately predicts the number of trapped atoms for all conditions. We also have investigated chirping the laser frequency and trapping with broadband light, neither of which increase the number of trapped atoms.

  11. 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.

  12. Sub-micro a-C:H patterning of silicon surfaces assisted by atmospheric-pressure plasma-enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Boileau, Alexis; Gries, Thomas; Noël, Cédric; Perito Cardoso, Rodrigo; Belmonte, Thierry

    2016-11-01

    Micro and nano-patterning of surfaces is an increasingly popular challenge in the field of the miniaturization of devices assembled via top-down approaches. This study demonstrates the possibility of depositing sub-micrometric localized coatings—spots, lines or even more complex shapes—made of amorphous hydrogenated carbon (a-C:H) thanks to a moving XY stage. Deposition was performed on silicon substrates using chemical vapor deposition assisted by an argon atmospheric-pressure plasma jet. Acetylene was injected into the post-discharge region as a precursor by means of a glass capillary with a sub-micrometric diameter. A parametric study was carried out to study the influence of the geometric configurations (capillary diameter and capillary-plasma distance) on the deposited coating. Thus, the patterns formed were investigated by scanning electron microscopy and atomic force microscopy. Furthermore, the chemical composition of large coated areas was investigated by Fourier transform infrared spectroscopy according to the chosen atmospheric environment. The observed chemical bonds show that reactions of the gaseous precursor in the discharge region and both chemical and morphological stability of the patterns after treatment are strongly dependent on the surrounding gas. Various sub-micrometric a-C:H shapes were successfully deposited under controlled atmospheric conditions using argon as inerting gas. Overall, this new process of micro-scale additive manufacturing by atmospheric plasma offers unusually high-resolution at low cost.

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

    PubMed

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

    2015-05-28

    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 SiOxμOFRR 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. PMID:25939851

  14. 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.

  15. 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.

  16. [The Relevance of MicroRNAs in Glioblastoma Stem Cells].

    PubMed

    Kleinová, R; Slabý, O; Šána, J

    2015-01-01

    Glioblastoma multiforme is the most common intracranial malignity of astrocyte origin in adults. Despite complex therapy consisting of maximal surgical resection, adjuvant concomitant chemoradiotherapy with temozolomide followed by temozolomide in monotherapy, the median of survival ranges between 12 and 15 months from dia-gnosis. This infaust prognosis is very often caused by both impossibility of achieving of sufficient radical surgical resection and tumor resistance to adjuvant therapy, which relates to the presence of glioblastoma stem cells. Similarly to normal stem cells, glioblastoma stem cells are capable of self -renewal, differentiation, and unlimited slow proliferation. Their resistance to conventional therapy is also due to higher expressions of DNA repair enzymes, antiapoptotic factors and multidrug transporters. Therefore, targeting these unique properties could be a novel promising therapeutic approach leading to more effective therapy and better prognosis of glioblastoma multiforme patients. One of the approaches how to successfully regulate above -mentioned properties is targeted regulation of microRNAs (miRNAs). These small noncoding RNA molecules posttranscriptionally regulate expression of more than 2/ 3 of all human genes that are also involved in stem cell associated signaling pathways. Moreover, deregulated expression of some miRNAs has been observed in many cancers, including glioblastoma multiforme. PMID:26480861

  17. Syngeneic Cardiac and Bone Marrow Stromal Cells Display Tissue-Specific microRNA Signatures and microRNA Subsets Restricted to Diverse Differentiation Processes

    PubMed Central

    Meraviglia, Viviana; Azzimato, Valerio; Piacentini, Luca; Chiesa, Mattia; Kesharwani, Rupesh K.; Frati, Caterina; Capogrossi, Maurizio C.; Gaetano, Carlo; Pompilio, Giulio

    2014-01-01

    MicroRNAs are key modulators at molecular level in different biological processes, including determination of cell fate and differentiation. Herein, microRNA expression profiling experiments were performed on syngeneic cardiac (CStC) and bone marrow (BMStC) mesenchymal stromal cells cultured in standard growth medium and then in vitro exposed to adipogenic, osteogenic, cardiomyogenic and endothelial differentiation media. Analysis identified a tissue-specific microRNA signature composed of 16 microRNAs that univocally discriminated cell type of origin and that were completely unaffected by in vitro differentiation media: 4 microRNAs were over-expressed in cardiac stromal cells, and 12 were overexpressed or present only in bone marrow stromal cells. Further, results revealed microRNA subsets specifically modulated by each differentiation medium, irrespective of the cell type of origin, and a subset of 7 microRNAs that were down-regulated by all media with respect to growth medium. Finally, we identified 16 microRNAs that were differentially modulated by the media when comparing the two tissues of origin. The existence of a tissue-specific microRNA signature surviving to any differentiation stimuli, strongly support the role if microRNAs determining cell identity related to tissue origin. Moreover, we identified microRNA subsets modulated by different culture conditions in a tissue-specific manner, pointing out their importance during differentiation processes. PMID:25232725

  18. Protein functionalized micro hydrogel features for cell-surface interaction.

    PubMed

    Bhatnagar, Parijat; Nixon, Alan J; Kim, Il; Kameoka, Jun

    2008-08-01

    Cross-linked hydrogel features have been patterned using subtractive lift-off of polymerized hydrogel film. Projection lithography and oxygen plasma etch was used to pattern parylene C polymer film. Molecular self-assembly of polymerizable monolayer was obtained in solution-phase and acrylamide based hydrogel was polymerized using free-radical polymerization on this substrate. Parylene C film was mechanically lifted-off to remove the blanket hydrogel film and micro hydrogel features (muhf) were obtained attached to the predefined patterns in the range from 1 to 60 mum. The muhf were functionalized with aldehyde functional groups, and proteins were coupled to them using Schiff base chemistry followed by reductive amination. Interaction of mesenchymal stem cells with transforming growth factor-beta 1 (TGF-beta1) functionalized muhf was studied, and TGF-beta1 was found to retain its tumor suppression activity. PMID:18259869

  19. 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.

  20. 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.

  1. MicroRNA signatures in B-cell lymphomas

    PubMed Central

    Di Lisio, L; Sánchez-Beato, M; Gómez-López, G; Rodríguez, M E; Montes-Moreno, S; Mollejo, M; Menárguez, J; Martínez, M A; Alves, F J; Pisano, D G; Piris, M A; Martínez, N

    2012-01-01

    Accurate lymphoma diagnosis, prognosis and therapy still require additional markers. We explore the potential relevance of microRNA (miRNA) expression in a large series that included all major B-cell non-Hodgkin lymphoma (NHL) types. The data generated were also used to identify miRNAs differentially expressed in Burkitt lymphoma (BL) and diffuse large B-cell lymphoma (DLBCL) samples. A series of 147 NHL samples and 15 controls were hybridized on a human miRNA one-color platform containing probes for 470 human miRNAs. Each lymphoma type was compared against the entire set of NHLs. BL was also directly compared with DLBCL, and 43 preselected miRNAs were analyzed in a new series of routinely processed samples of 28 BLs and 43 DLBCLs using quantitative reverse transcription-polymerase chain reaction. A signature of 128 miRNAs enabled the characterization of lymphoma neoplasms, reflecting the lymphoma type, cell of origin and/or discrete oncogene alterations. Comparative analysis of BL and DLBCL yielded 19 differentially expressed miRNAs, which were confirmed in a second confirmation series of 71 paraffin-embedded samples. The set of differentially expressed miRNAs found here expands the range of potential diagnostic markers for lymphoma diagnosis, especially when differential diagnosis of BL and DLBCL is required. PMID:22829247

  2. 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.

  3. 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%.

  4. 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

  5. 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 §...

  6. 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 §...

  7. 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 §...

  8. 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 §...

  9. 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 §...

  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. 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.

  12. 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.

  13. 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

    2015-09-14

    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.

  14. 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

  15. 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.

  16. 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

  17. 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.

  18. Identification of microprocessor-dependent cancer cells allows screening for growth-sustaining micro-RNAs.

    PubMed

    Peric, D; Chvalova, K; Rousselet, G

    2012-04-19

    Micro-RNAs are deregulated in cancer cells, and some are either tumor suppressive or oncogenic. In addition, a link has been established between decreased expression of micro-RNAs and transformation, and several proteins of the RNA interference pathway have been shown to be haploinsufficient tumor suppressors. Oncogenic micro-RNAs (oncomiRs) could represent new therapeutic targets, and their identification is therefore crucial. However, structural and functional redundancy between micro-RNAs hampers approaches relying on individual micro-RNA inhibition. We reasoned that in cancer cells that depend on oncomiRs, impairing the micro-RNA pathway could lead to growth perturbation rather than increased tumorigenesis. Identifying such cells could allow functional analyses of individual micro-RNAs by complementation of the phenotypes observed upon global micro-RNA inhibition. Therefore, we developed episomal vectors coding for small hairpin RNAs targeting either Drosha or DGCR8, the two components of the microprocessor, the nuclear micro-RNA maturation complex. We identified cancer cell lines in which both vectors induced colony growth arrest. We then screened for individual micro-RNAs complementing this growth arrest, and identified miR-19a, miR-19b, miR-20a and miR-27b as major growth-sustaining micro-RNAs. However, the effect of miR-19a and miR-19b was only transient. In addition, embryonic stem cell-derived micro-RNAs with miR-20a seeds were much less efficient than miR-20a in sustaining cancer cell growth, a finding that contrasted with results obtained in stem cells. Finally, we showed that the tumor suppressor phosphatase and tensin homologue deleted on chromosome 10, a shared target of miR-19 and miR-20, was functionally involved in the growth arrest induced by microprocessor inhibition. We conclude that our approach allowed to identify microprocessor-dependent cancer cells, which could be used to screen for growth-sustaining micro-RNAs. This complementation screen

  19. 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.

  20. 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

  1. 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

    2016-04-04

    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.

  2. 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

  3. Homodyne Microwave Electric Field Measurements Using Cesium Rydberg Atoms in Vapor Cells

    NASA Astrophysics Data System (ADS)

    Fan, Haoquan; Kumar, Santosh; Shaffer, James

    2015-05-01

    Probe laser noise is one of the main factors limiting the sensitivity of microwave electric field measurements that use Rydberg atoms in vapor cells. We apply a homodyne detection technique using a Mach-Zehnder interferometer to achieve a new sensitivity limit for the measurement of microwave electric fields, 3 - 5 μV cm-1√{ Hz }-1 . The new sensitivity is almost one order of magnitude better than the previous results presented in Ref. [Nat. Phys. 8, 819 (2012)]. We also report on the homogeneous dephasing effects caused by transit time broadening, collision broadening, and the lifetime of Rydberg atoms which we can now directly observe. We show that these dephasing effects are the fundamental limiting factors that determine the shot noise limit.

  4. 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.

  5. 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).

  6. 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.

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

    PubMed

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

    2015-08-01

    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.

  8. 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.

  9. Cytotoxicity and mutagenicity of vapor-phase pollutants in rat lung epithelial cells and Chinese hamster ovary cells grown on collagen gels

    SciTech Connect

    Zamora, P.O.; Benson, J.M.; Marshall, T.C.; Mokler, B.V.; Li, A.P.; Dahl, A.R.; Brooks, A.L.; McClellan, R.O.

    1983-01-01

    Lung epithelial cell (cell line designated LEC) and Chinese hamster ovary (CHO) cells were grown on hydrated collagen gels and exposed directly to toxic vapor-phase pollutants. The cells were exposed to graded concentrations of phenol, formaldehyde, a volatile fraction of process stream material from an experimental coal gasifier, and the nonparticulate, vapor phase of diesel engine exhaust. During exposures, the cells were maintained at an air/collagen interface by removing the medium overlying the hydrated collagen gel. Morphological changes indicative of cell retraction were found in LEC cell cultures exposed to phenol, formaldehyde, or diesel exhaust. Damage following exposure to the toxicants was quantitated in LEC and CHO cells by Trypan blue dye exclusion, a measure of plasma membrane integrity. Clone-forming ability was also used to measure cell survival in CHO cells. When measured by Trypan blue dye exclusion, phenol (EC50 = 2.1 mg/l) caused membrane damage to LEC cells but not CHO cells, while formaldehyde (EC50 = 31 and 42 ..mu..g/l for LEC and CHO, respectively) and diesel exhaust (EC50 = 11 and 29% of tailpipe exhaust in LEC and CHO cells, respectively) caused damage to both cell types. No cytotoxicity was observed in LEC or CHO cells exposed to the fraction from the coal gasifier. Essentially no mutagenic activity was associated with the exposure of CHO cells to formaldehyde or the vapor phase of diesel exhaust. Mutagenic activity was found in CHO cells exposed to ethylene oxide, the positive control.

  10. 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.

  11. 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

  12. 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.

  13. 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%.

  14. 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.

  15. 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

  16. Quantitative passive soil vapor sampling for VOCs--Part 4: Flow-through cell.

    PubMed

    McAlary, Todd; Groenevelt, Hester; Seethapathy, Suresh; Sacco, Paolo; Crump, Derrick; Tuday, Michael; Schumacher, Brian; Hayes, Heidi; Johnson, Paul; Parker, Louise; Górecki, Tadeusz

    2014-05-01

    This paper presents a controlled experiment comparing several quantitative passive samplers for monitoring concentrations of volatile organic compound (VOC) vapors in soil gas using a flow-through cell. This application is simpler than conventional active sampling using adsorptive tubes because the flow rate does not need to be precisely measured and controlled, which is advantageous because the permeability of subsurface materials affects the flow rate and the permeability of geologic materials is highly variable. Using passive samplers in a flow-through cell, the flow rate may not need to be known exactly, as long as it is sufficient to purge the cell in a reasonable time and minimize any negative bias attributable to the starvation effect. An experiment was performed in a 500 mL flow-through cell using a two-factor, one-half fraction fractional factorial test design with flow rates of 80, 670 and 930 mL min(-1) and sample durations of 10, 15 and 20 minutes for each of five different passive samplers (passive Automatic Thermal Desorption Tube, Radiello®, SKC Ultra, Waterloo Membrane Sampler™ and 3M™ OVM 3500). A Summa canister was collected coincident with each passive sampler and analyzed by EPA Method TO-15 to provide a baseline for comparison of the passive sampler concentrations. The passive sampler concentrations were within a factor of 2 of the Summa canister concentrations in 32 of 35 cases. Passive samples collected at the low flow rate and short duration showed low concentrations, which is likely attributable to insufficient purging of the cell after sampler placement.

  17. 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.

  18. Very thin and stable thin-film silicon alloy triple junction solar cells by hot wire chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Veldhuizen, L. W.; Schropp, R. E. I.

    2016-08-01

    We present a silicon-based triple junction solar cell that requires a deposition time of less than 15 min for all photoactive layers. As a low-bandgap material, we used thin layers of hydrogenated amorphous silicon germanium with lower band gap than commonly used, which is possible due to the application of hot wire chemical vapor deposition. The triple junction cell shows an initial energy conversion efficiency exceeding 10%, and with a relative performance stability within 6%, the cell shows a high tolerance to light-induced degradation. With these results, we help to demonstrate that hot wire chemical vapor deposition is a viable deposition method for the fabrication of low-cost solar cells.

  19. Life on Magnets: Stem Cell Networking on Micro-Magnet Arrays

    PubMed Central

    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

  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.

  1. Moisturized anode and water management in a passive vapor-feed direct methanol fuel cell operated with neat methanol

    NASA Astrophysics Data System (ADS)

    Zhang, Zhaochun; Yuan, Wei; Wang, Aoyu; Yan, Zhiguo; Tang, Yong; Tang, Kairui

    2015-11-01

    This paper investigates the moisturized anode and water management of a vapor-feed direct methanol fuel cell operated with neat methanol. Three methods of water management are experimentally compared, including water storage in a fuel reservoir, active water vapor supply and water recovery from the cathode to the anode. A water management layer for water recovery is introduced to the cathode, which is made of a quasi-superhydrophobic sintered porous metal plate (SPMP) to enhance water back diffusion (WBD). Results prove that each of these methods can improve the cell performance. WBD enhancement based on the use of a SPMP is proven to be the most effective way. It is also found that combination of different methods may more promote the cell performance. Using a WBD enhancement layer under the condition of active water vapor supply can completely eliminate performance decline in the early stage of constant-load discharging. For fully-passive operation, a higher catalyst loading at the cathode helps retain stable performance when a WBD enhancement layer is used. Based on this design, the passive vapor-feed DMFC fed with neat methanol can achieve a maximum power density of 21 mW cm-2.

  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. Nuclear receptors and microRNAs: Who regulates the regulators in neural stem cells?

    PubMed

    Eendebak, Robert J A H; Lucassen, Paul J; Fitzsimons, Carlos P

    2011-03-01

    In this mini-review, we focus on regulatory loops between nuclear receptors and microRNAs, an emerging class of small RNA regulators of gene expression. Evidence supporting interactions between microRNAs and nuclear receptors in the regulation of gene expression networks is discussed in relation to its possible role in neural stem cell self renewal and differentiation. Furthermore, we discuss possible disturbances of the regulatory loops between microRNAs and nuclear receptors in human neurodegenerative disease. Finally, we discuss the possible use of nuclear receptors as pharmacological entry points to regulate neural stem cell self-renewal and differentiation.

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

    PubMed

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

    2015-07-23

    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 Hras(G12V) on the transcriptome of keratinocytes. We discover that microRNA-203 is downregulated by Hras(G12V). 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.

  6. 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

  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. 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

  9. 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.

  10. 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.

  11. 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.

  12. Investigation of antirelaxation coatings for alkali-metal vapor cells using surface science techniques

    NASA Astrophysics Data System (ADS)

    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.; Kimball, D. F. Jackson; 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.

    2010-10-01

    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.

  13. 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.

  14. 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…

  15. 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)

  16. 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.

  17. 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

  18. 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.

  19. Magnet-Bead Based MicroRNA Delivery System to Modify CD133+ Stem Cells

    PubMed Central

    Wiekhorst, Frank; Steinhoff, Gustav

    2016-01-01

    Aim. CD133+ stem cells bear huge potential for regenerative medicine. However, low retention in the injured tissue and massive cell death reduce beneficial effects. In order to address these issues, we intended to develop a nonviral system for appropriate cell engineering. Materials and Methods. Modification of human CD133+ stem cells with magnetic polyplexes carrying microRNA was studied in terms of efficiency, safety, and targeting potential. Results. High microRNA uptake rates (~80–90%) were achieved without affecting CD133+ stem cell properties. Modified cells can be magnetically guided. Conclusion. We developed a safe and efficient protocol for CD133+ stem cell modification. Our work may become a basis to improve stem cell therapeutical effects as well as their monitoring with magnetic resonance imaging. PMID:27795713

  20. 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.

  1. 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

  2. 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

  3. 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

  4. 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.

  5. 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

  6. An osmotic micro-pump integrated on a microfluidic chip for perfusion cell culture.

    PubMed

    Xu, Zhang-Run; Yang, Chun-Guang; Liu, Cui-Hong; Zhou, Zhe; Fang, Jin; Wang, Jian-Hua

    2010-01-15

    A novel microfluidic chip integrating an osmosis-based micro-pump was developed and used for perfusion cell culture. The micro-pump includes two sealed chambers, i.e., the inner osmotic reagent chamber and the outer water chamber, sandwiching a semi-permeable membrane. The water in the outer chamber was forced to flow through the membrane into the inner chamber via osmosis, facilitating continuous flow of fluidic zone in the channel. An average flow rate of 0.33microLmin(-1) was obtained within 50h along with a precision of 4.3% RSD (n=51) by using a 100mgmL(-1) polyvinylpyrrolidone (PVP) solution as the osmotic driving reagent and a flow passage area of 0.98cm(2) of the semi-permeable membrane. The power-free micro-pump has been demonstrated to be pulse-free offering stable flow rates during long-term operation. The present microfluidic chip has been successfully applied for the perfusion culture of human colorectal carcinoma cell by continuously refreshing the culture medium with the osmotic micro-pump. In addition, in situ cell immunostaining was also performed on the microchip by driving all the reagent zones with the integrated micro-pump.

  7. 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

  8. 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.

  9. 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

  10. 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

  11. 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

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. Mesenchymal stem cell growth behavior on micro/nano hierarchical surfaces of titanium substrates.

    PubMed

    Shen, Xinkun; Ma, Pingping; Hu, Yan; Xu, Gaoqiang; Zhou, Jun; Cai, Kaiyong

    2015-03-01

    Surface topography of an orthopedic implant plays an essential role in the regulation of bone formation with surrounding bone tissue. To investigate the effects of surface topography of titanium (Ti) substrates on cellular behavior of mesenchymal stem cells (MSCs), a series of micro/nano hierarchical structures were fabricated onto micro-structured titanium (Micro-Ti) substrates via a sol-gel method with spin-coat technique. Scanning electron microscopy (SEM), surface profiler, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and water contact angle measurement were employed to certify the successful fabrication of micro/nano hierarchical structures with the presence of various nano-sized TiO2 grains (20 nm, 40 nm and 80 nm, respectively) onto micro-structured surfaces. The formation mechanism of the micro/nano hierarchical structures was proposed. Moreover, the effects of those hierarchical structures on the growth behavior of MSCs were evaluated both on cellular and molecular levels in vitro. The results confirmed that micro/nano hierarchical structures with large grains (80 nm) greatly promoted the proliferation and differentiation of MSCs comparing with other small grains (20 nm and 40 nm). The study provides an alternative for the fabrication of hierarchically structured Ti implants for potential orthopedic application.

  17. How microRNA and transcription factor co-regulatory networks affect osteosarcoma cell proliferation.

    PubMed

    Poos, Kathrin; Smida, Jan; Nathrath, Michaela; Maugg, Doris; Baumhoer, Daniel; Korsching, Eberhard

    2013-01-01

    Osteosarcomas (OS) are complex bone tumors with various genomic alterations. These alterations affect the expression and function of several genes due to drastic changes in the underlying gene regulatory network. However, we know little about critical gene regulators and their functional consequences on the pathogenesis of OS. Therefore, we aimed to determine microRNA and transcription factor (TF) co-regulatory networks in OS cell proliferation. Cell proliferation is an essential part in the pathogenesis of OS and deeper understanding of its regulation might help to identify potential therapeutic targets. Based on expression data of OS cell lines divided according to their proliferative activity, we obtained 12 proliferation-related microRNAs and corresponding target genes. Therewith, microRNA and TF co-regulatory networks were generated and analyzed regarding their structure and functional influence. We identified key co-regulators comprising the microRNAs miR-9-5p, miR-138, and miR-214 and the TFs SP1 and MYC in the derived networks. These regulators are implicated in NFKB- and RB1-signaling and focal adhesion processes based on their common or interacting target genes (e.g., CDK6, CTNNB1, E2F4, HES1, ITGA6, NFKB1, NOTCH1, and SIN3A). Thus, we proposed a model of OS cell proliferation which is primarily co-regulated through the interactions of the mentioned microRNA and TF combinations. This study illustrates the benefit of systems biological approaches in the analysis of complex diseases. We integrated experimental data with publicly available information to unravel the coordinated (post)-transcriptional control of microRNAs and TFs to identify potential therapeutic targets in OS. The resulting microRNA and TF co-regulatory networks are publicly available for further exploration to generate or evaluate own hypotheses of the pathogenesis of OS (http://www.complex-systems.uni-muenster.de/co_networks.html).

  18. Analysis of microRNA Levels in Intestinal Epithelial Cells.

    PubMed

    Nguyen, Hang Thi Thu

    2016-01-01

    The field of microRNA (miRNA) research is expanding rapidly with the crucial role of miRNAs in almost every biological process and their implication in many diseases. The role of miRNAs in modulating inflammatory responses in the gut has attracted many research groups including us. Here, we first briefly summarize our current understanding of the role of miRNAs in maintaining and regulating gut physiopathology and in inflammatory bowel diseases. We then describe in detail our techniques to analyze miRNA levels with notes that we have collected and summarized during our experiments. PMID:27246025

  19. Algorithm for evaluation of temperature distribution of a vapor cell in a diode-pumped alkali laser system: part I.

    PubMed

    Han, Juhong; Wang, You; Cai, He; Zhang, Wei; Xue, Liangping; Wang, Hongyuan

    2014-06-01

    A diode-pumped alkali laser (DPAL) is one of the most hopeful candidates to achieve high power performances. As the laser medium is in a gas-state, populations of energy-levels of a DPAL are strongly dependent on the vapor temperature. Thus, the temperature distribution directly determines the output characteristics of a DPAL. In this report, we developed a systematic model by combining the procedures of heat transfer and laser kinetics together to explore the radial temperature distribution in the transverse section of a cesium vapor cell. A cyclic iterative approach is adopted to calculate the population densities. The corresponding temperature distributions have been obtained for different beam waists and pump powers. The conclusion is thought to be useful for realizing a DPAL with high output power.

  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.

  1. 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

  2. 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

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

    PubMed

    Sladitschek, Hanna L; Neveu, Pierre A

    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.

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

    PubMed

    Sladitschek, Hanna L; Neveu, Pierre A

    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

  5. 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

  6. Plasma-enhanced chemical vapor deposition of n-heptane and methyl methacrylate for potential cell alignment applications.

    PubMed

    Steinbach, Annina; Tautzenberger, Andrea; Schaller, Andreas; Kalytta-Mewes, Andreas; Tränkle, Sebastian; Ignatius, Anita; Volkmer, Dirk

    2012-10-24

    Plasma-enhanced chemical vapor deposited polymers (plasma polymers) are promising candidates for biomaterials applications. In the present study, plasma deposition as a fast and easily scalable method was adapted to deposit coatings from n-heptane and methyl methacrylate monomers onto glass substrates. Linear patterns with line and groove widths between 1.25 and 160 μm were introduced by degrative UV-lithography for cell alignment. Differential interference contrast optical microscopy, profilometry and atomic force microscopy revealed that the patterned surfaces had a smooth, homogeneous appearance and a pattern height of 8 and 45 nm for plasma deposited n-heptane and methyl methacrylate, respectively. UV-lithography increased the oxygen content on the surface drastically as shown by X-ray photoelectron spectroscopy. After immersion in simulated body fluid for 21 days, the pattern was still intact, and the ester groups were also maintained for the most part as shown by infrared spectroscopy. To test the coatings' potential applicability for biomaterial surfaces in a preliminary experiment, we cultured murine preosteoblastic MC3T3-E1 cells on these coatings. Light and electron microscopically, a normal spindle-shaped and aligned cell morphology was observed. At the mRNA level, cells showed no signs of diminished proliferation or elevated expression of apoptosis markers. In conclusion, plasma-enhanced chemical vapor deposited polymers can be patterned with a fast and feasible method and might be suitable materials to guide cell alignment. PMID:22992135

  7. 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

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

    PubMed

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

    2008-08-01

    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.

  9. 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.

  10. 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.

  11. VAPOR VALVE

    DOEpatents

    Wouters, L.F.

    1959-08-25

    Electromagnetically operated vapor valves are described for apparatus employed in the separation of isotopes or elements to control the flow of gaseous vapors between a vaporizing charge chamber and an ionizing chamber, The charge chamber and ionizing chamber are positioned in a magnetic field, and the flow of vapors through an orifice connecting the chambers is regulated by regulating the flow of current through a resilient metal strip rigidly mounted at one end and positioned in the magnetic field adjacent to the orifice.

  12. 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.

  13. The Genomic Analysis of Erythrocyte microRNA Expression in Sickle Cell Diseases

    PubMed Central

    Chen, Shao-Yin; Wang, Yulei; Telen, Marilyn J.; Chi, Jen-Tsan

    2008-01-01

    Background Since mature erythrocytes are terminally differentiated cells without nuclei and organelles, it is commonly thought that they do not contain nucleic acids. In this study, we have re-examined this issue by analyzing the transcriptome of a purified population of human mature erythrocytes from individuals with normal hemoglobin (HbAA) and homozygous sickle cell disease (HbSS). Methods and Findings Using a combination of microarray analysis, real-time RT-PCR and Northern blots, we found that mature erythrocytes, while lacking ribosomal and large-sized RNAs, contain abundant and diverse microRNAs. MicroRNA expression of erythrocytes was different from that of reticulocytes and leukocytes, and contributed the majority of the microRNA expression in whole blood. When we used microRNA microarrays to analyze erythrocytes from HbAA and HbSS individuals, we noted a dramatic difference in their microRNA expression pattern. We found that miR-320 played an important role for the down-regulation of its target gene, CD71 during reticulocyte terminal differentiation. Further investigation revealed that poor expression of miR-320 in HbSS cells was associated with their defective downregulation CD71 during terminal differentiation. Conclusions In summary, we have discovered significant microRNA expression in human mature erythrocytes, which is dramatically altered in HbSS erythrocytes and their defect in terminal differentiation. Thus, the global analysis of microRNA expression in circulating erythrocytes can provide mechanistic insights into the disease phenotypes of erythrocyte diseases. PMID:18523662

  14. Blood cell mRNAs and microRNAs: optimized protocols for extraction and preservation.

    PubMed

    Eikmans, Michael; Rekers, Niels V; Anholts, Jacqueline D H; Heidt, Sebastiaan; Claas, Frans H J

    2013-03-14

    Assessing messenger RNA (mRNA) and microRNA levels in peripheral blood cells may complement conventional parameters in clinical practice. Working with small, precious samples requires optimal RNA yields and minimal RNA degradation. Several procedures for RNA extraction and complementary DNA (cDNA) synthesis were compared for their efficiency. The effect on RNA quality of freeze-thawing peripheral blood cells and storage in preserving reagents was investigated. In terms of RNA yield and convenience, quality quantitative polymerase chain reaction signals per nanogram of total RNA and using NucleoSpin and mirVana columns is preferable. The SuperScript III protocol results in the highest cDNA yields. During conventional procedures of storing peripheral blood cells at -180°C and thawing them thereafter, RNA integrity is maintained. TRIzol preserves RNA in cells stored at -20°C. Detection of mRNA levels significantly decreases in degraded RNA samples, whereas microRNA molecules remain relatively stable. When standardized to reference targets, mRNA transcripts and microRNAs can be reliably quantified in moderately degraded (quality index 4-7) and severely degraded (quality index <4) RNA samples, respectively. We describe a strategy for obtaining high-quality and quantity RNA from fresh and stored cells from blood. The results serve as a guideline for sensitive mRNA and microRNA expression assessment in clinical material.

  15. [Recent Advances on the Immunoregulation of MicroRNA-155 in Mesenchymal Stem Cells--Review].

    PubMed

    Han, Xiao; Wang, Lei; Wu, Tao; Bai, Hai

    2016-02-01

    Mesenchymal stem cells (MSC) are capable of immunosuppression and differentiating into multiple cell lineages. MSC, which are accessed easily and less side-effects, have been a source of seed cells in tissue-engineering and cell-therapy. However, the application of MSC are limited by their differentiation of instability and easy aging. MicroRNA-155 (miR-155) is one of microRNA, which has powerful regulatory potential in a wide variety of immune cells through degrading specific mRNA after transcription and inhibiting translation of the target genes. Following the research of miR-155 deeply, it has an indispensable role in the proliferation, differentiation and immunoregulation of MSC. This review discusses the current understandings for the role of miR-155 in MSC.

  16. 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).

  17. Prediction of anisotropic behavior of nano/micro composite based on damage mechanics with cell modeling.

    PubMed

    Lee, Dock-Jin; Kim, Young-Jin; Kim, Moon-Ki; Choi, Jae-Boong; Chang, Yoon-Suk; Liu, Wing Kam

    2011-01-01

    New advanced composite materials have recently been of great interest. Especially, many researchers have studied on nano/micro composites based on matrix filled with nano-particles, nano-tubes, nano-wires and so forth, which have outstanding characteristics on thermal, electrical, optical, chemical and mechanical properties. Therefore, the need of numerical approach for design and development of the advanced materials has been recognized. In this paper, finite element analysis based on multi-resolution continuum theory is carried out to predict the anisotropic behavior of nano/micro composites based on damage mechanics with a cell modeling. The cell modeling systematically evaluates constitutive relationships from microstructure of the composite material. Effects of plastic anisotropy on deformation behavior and damage evolution of nano/micro composite are investigated by using Hill's 48 yield function and also compared with those obtained from Gurson-Tvergaard-Needleman isotropic damage model based on von Mises yield function.

  18. Porous silica supports for micro-Raman spectroscopic studies of individual living cells

    NASA Astrophysics Data System (ADS)

    Cristini-Robbe, O.; Raulin, K.; Dubart, F.; Bernard, R.; Kinowski, C.; Damene, N.; El Yazidi, I.; Boed, A.; Turrell, S.

    2013-10-01

    A work was undertaken to explore the possibility of using porous silica gels as support materials for in vitro studies of individual living cells. Accordingly, tetra methyl orthosilicate-derived silica xerogels were prepared and tested as substrates for human breast adenocarcinoma MCF-7 cells. Micro-Raman spectra and BET measurements were used to determine the effect of sol-pH and autoclave sterilization on the substrate. MCF-7 cells were then seeded and grown on the resulting silica gels. Combined techniques show that (a) sol-pH affects substrate porosity and (b) autoclave conditions affect only the substrate surface thus increasing the surface porosity. Micro-Raman spectra of in situ grown MCF-7 cells indicate that they proliferate well on these xerogel surfaces with a preference for base-catalyzed substrates and that the surface morphology of supports can have a definite effect on the adherence and on the life time of human cells. Spectral evolutions observed for cells over a period of 48 h have made it possible to show that these substrates enable the easy maintenance of cell viability for over 36 h and that micro-Raman techniques make it possible to study individual cells and to characterize evolutional changes at different stages of their life-times. Results point to these new porous silica supports as promising substrates for rapid screening of drug toxicity.

  19. 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.

  20. 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

  1. 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.

  2. 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

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

    DOE PAGES

    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

  4. 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.

  5. 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

  6. 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

  7. Cell and tissue behavior on micro-grooved surfaces.

    PubMed

    Walboomers, X F; Jansen, J A

    2001-11-01

    In this review, we discuss substrates and implant surfaces provided with micrometer-sized groove and ridge patterns. Such "microgrooves" influence cell behavior: the cells align themselves, and migrate guided by the surface grooves. This phenomenon is known as "contact guidance". First, cell structure and cell attachment behavior are described. Then techniques for the production of microgrooves are addressed, and a summary is given of a number of previous in-vitro and in-vivo experiments on this subject. Based on the knowledge of cell movement, we suggest a theory involving the dynamics of fibrous cellular components in the filopodium. Finally, future directions for this type of research, and implications for medical and dental implantology, are addressed.

  8. Analysis of microRNA transcription and post-transcriptional processing by Dicer in the context of CHO cell proliferation

    PubMed Central

    Hackl, Matthias; Jadhav, Vaibhav; Klanert, Gerald; Karbiener, Michael; Scheideler, Marcel; Grillari, Johannes; Borth, Nicole

    2014-01-01

    CHO cells are the mammalian cell line of choice for recombinant production of therapeutic proteins. However, their low rate of proliferation limits obtainable space-time yields due to inefficient biomass accumulation. We set out to correlate microRNA transcription to cell-specific growth-rate by microarray analysis of 5 CHO suspension cell lines with low to high specific growth rates. Global microRNA expression analysis and Pearson correlation studies showed that mature microRNA transcript levels are predominately up-regulated in a state of fast proliferation (46 positively correlated, 17 negatively correlated). To further validate this observation, the expression of three genes that are central to microRNA biogenesis (Dicer, Drosha and Dgcr8) was analyzed. The expression of Dicer, which mediates the final step in microRNA maturation, was found to be strongly correlated to growth rate. Accordingly, knockdown of Dicer impaired cell growth by reducing growth-correlating microRNA transcripts. Moderate ectopic overexpression of Dicer positively affected cell growth, while strong overexpression impaired growth, presumably due to the concomitant increase of microRNAs that inhibit cell growth. Our data therefore suggest that Dicer dependent microRNAs regulate CHO cell proliferation and that Dicer could serve as a potential surrogate marker for cellular proliferation. PMID:24486028

  9. Bioluminescence tracking of alginate micro-encapsulated cell transplants.

    PubMed

    Tiernan, Aubrey R; Sambanis, Athanassios

    2014-07-22

    Cell-based therapies to treat loss-of-function hormonal disorders such as diabetes and Parkinson's disease are routinely coupled with encapsulation strategies, but an understanding of when and why grafts fail in vivo is lacking. Consequently, investigators cannot clearly define the key factors that influence graft success. Although bioluminescence is a popular method to track the survival of free cells transplanted in preclinical models, little is known of the ability to use bioluminescence for real-time tracking of microencapsulated cells. Furthermore, the impact that dynamic imaging distances may have, due to freely-floating microcapsules in vivo, on cell survival monitoring is unknown. This work addresses these questions by applying bioluminescence to a pancreatic substitute based on microencapsulated cells. Recombinant insulin-secreting cells were transduced with a luciferase lentivirus and microencapsulated in Ba(2+) crosslinked alginate for in vitro and in vivo studies. In vitro quantitative bioluminescence monitoring was possible and viable microencapsulated cells were followed in real time under both normoxic and anoxic conditions. Although in vivo dispersion of freely-floating microcapsules in the peritoneal cavity limited the analysis to a qualitative bioluminescence evaluation, signals consistently four orders of magnitude above background were clear indicators of temporal cell survival. Strong agreement between in vivo and in vitro cell proliferation over time was discovered by making direct bioluminescence comparisons between explanted microcapsules and parallel in vitro cultures. Broader application of this bioluminescence approach to retrievable transplants, in supplement to currently used end-point physiological tests, could improve understanding and accelerate development of cell-based therapies for critical clinical applications. Copyright © 2014 John Wiley & Sons, Ltd.

  10. 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

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

    PubMed

    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.

  12. Micro-particle transporting system using galvanotactically stimulated apo-symbiotic cells of Paramecium bursaria.

    PubMed

    Furukawa, Shunsuke; Karaki, Chiaki; Kawano, Tomonori

    2009-01-01

    It is well known that Paramecium species including green paramecia (Paramecium bursaria) migrate towards the anode when exposed to an electric field in a medium. This type of a cellular movement is known as galvanotaxis. Our previous study revealed that an electric stimulus given to P bursaria is converted to a galvanotactic cellular movement by involvement of T-type calcium channel on the plasma membrane [Aonuma et al. (2007), Z. Naturforsch. 62c, 93-102]. This phenomenon has attracted the attention of bioengineers in the fields of biorobotics or micro-robotics in order to develop electrically controllable micromachineries. Here, we demonstrate the galvanotactic controls of the cellular migration of P bursaria in capillary tubes (diameter, 1-2 mm; length, 30-240 mm). Since the Paramecium cells take up particles of various sizes, we attempted to use the electrically stimulated cells of P bursaria as the vehicle for transportation of micro-particles in the capillary system. By using apo-symbiotic cells of P bursaria obtained after forced removal of symbiotic algae, the uptake of the particles could be maximized and visualized. Then, electrically controlled transportations of particle-filled apo-symbiotic P bursaria cells were manifested. The particles transported by electrically controlled cells (varying in size from nm to /m levels) included re-introduced green algae, fluorescence-labeled polystyrene beads, magnetic microspheres, emerald green fluorescent protein (EmGFP)-labeled cells of E. coli, Indian ink, and crystals of zeolite (hydrated aluminosilicate minerals with a micro-porous structure) and some metal oxides. Since the above demonstrations were successful, we concluded that P bursaria has a potential to be employed as one of the micro-biorobotic devices used in BioMEMS (biological micro-electro-mechanical systems).

  13. 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

  14. 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

  15. Jarid2 links MicroRNA and chromatin in Th17 cells.

    PubMed

    Merkenschlager, Matthias

    2014-06-19

    In this issue of Immunity, Escobar et al. (2014) bring microRNAs and chromatin together by showing how activation-induced miR-155 targets the chromatin protein Jarid2 to regulate proinflammatory cytokine production in T helper 17 cells.

  16. 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}.

  17. 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.

  18. Performance comparison of digital microRNA profiling technologies applied on human breast cancer cell lines.

    PubMed

    Knutsen, Erik; Fiskaa, Tonje; Ursvik, Anita; Jørgensen, Tor Erik; Perander, Maria; Lund, Eiliv; Seternes, Ole Morten; Johansen, Steinar D; Andreassen, Morten

    2013-01-01

    MicroRNA profiling represents an important first-step in deducting individual RNA-based regulatory function in a cell, tissue, or at a specific developmental stage. Currently there are several different platforms to choose from in order to make the initial miRNA profiles. In this study we investigate recently developed digital microRNA high-throughput technologies. Four different platforms were compared including next generation SOLiD ligation sequencing and Illumina HiSeq sequencing, hybridization-based NanoString nCounter, and miRCURY locked nucleic acid RT-qPCR. For all four technologies, full microRNA profiles were generated from human cell lines that represent noninvasive and invasive tumorigenic breast cancer. This study reports the correlation between platforms, as well as a more extensive analysis of the accuracy and sensitivity of data generated when using different platforms and important consideration when verifying results by the use of additional technologies. We found all the platforms to be highly capable for microRNA analysis. Furthermore, the two NGS platforms and RT-qPCR all have equally high sensitivity, and the fold change accuracy is independent of individual miRNA concentration for NGS and RT-qPCR. Based on these findings we propose new guidelines and considerations when performing microRNA profiling.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Plant micro- and nanomechanics: experimental techniques for plant cell-wall analysis.

    PubMed

    Burgert, Ingo; Keplinger, Tobias

    2013-11-01

    In the last few decades, micro- and nanomechanical methods have become increasingly important analytical techniques to gain deeper insight into the nanostructure and mechanical design of plant cell walls. The objective of this article is to review the most common micro- and nanomechanical approaches that are utilized to study primary and secondary cell walls from a biomechanics perspective. In light of their quite disparate functions, the common and opposing structural features of primary and secondary cell walls are reviewed briefly. A significant part of the article is devoted to an overview of the methodological aspects of the mechanical characterization techniques with a particular focus on new developments and advancements in the field of nanomechanics. This is followed and complemented by a review of numerous studies on the mechanical role of cellulose fibrils and the various matrix components as well as the polymer interactions in the context of primary and secondary cell-wall function.

  6. Taxane recovery from cells of taxus in micro- and hypergravity

    NASA Astrophysics Data System (ADS)

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

    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™), 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 2·10 -4.g, taxane recovery was reduced but biomass growth and percent paclitaxel was significantly increased. At 1 to 24·g, 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.

  7. 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.

  8. 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

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

    PubMed

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

    2015-06-01

    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.

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

    DOE PAGES

    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

  11. 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%.

  12. Design of a physical vapor transport cell for time controlled deposition of nucleation phase organic thin films.

    PubMed

    Mea, Jesse S; Gauvin, Serge; Ashrit, P V

    2007-04-01

    A portable high vacuum chamber has been designed to implement a solenoid operated shutter used as a substrate cache during short duration deposition of organic thin films via the physical vapor transport (PVT) method. This PVT cell was designed for the study of gravity effects on nucleation phase organic thin films obtained in laboratory unit g conditions and especially low g conditions found onboard parabolic flights. The design challenges met were, notably, the timely control of deposition on the substrate during parabolas and maintenance of the experimental cell pressure during operation of the shutter. Nucleation phase thin films of the organic hole transporting semiconductor N,N' -bis(3-methylphenyl)-N,N' -bis(phenyl)benzidine (TPD), obtained with the use of the PVT cells, show that the moving shutter has an effect on the convective PVT gas flow; however, as convection is reduced, this effect is observed to be equally reduced.

  13. 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

  14. 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.

  15. Clinicopathological significance of microRNA-214 in gastric cancer and its effect on cell biological behaviour.

    PubMed

    Wang, Ya-Wen; Shi, Duan-Bo; Chen, Xu; Gao, Chao; Gao, Peng

    2014-01-01

    Accumulating evidence indicates that numerous microRNAs are involved in the tumorigenesis and progression of gastric cancer, while the clinical significance of microRNA-214 in gastric cancer is poorly understood and the exact role of microRNA-214 in gastric cancer remains obscure. In the present study, expression levels of microRNA-214 in 80 gastric carcinoma tissues, 18 nontumourous gastric tissues, and 4 types of gastric cancer cell lines were quantified by reverse transcription followed by real-time quantitative polymerase chain reaction (RT-qPCR), and the relationship between microRNA-214 expression and cliniopathological characteristics including prognosis was explored. To investigate the potential role of microRNA-214 in gastric cancer cell biological behaviour, we performed cell proliferation, apoptosis, migration and invasion assays in four gastric cancer cell lines and an immortalized gastric cell line in vitro. Our results showed that microRNA-214 was dramatically downregulated in gastric cancer tissues and gastric cancer cell lines, compared with nontumourous gastric tissues. Stepwise downregulation of microRNA-214 expression was observed among nontumourous gastric mucosa, nonmetastasis gastric cancer tissues, and metastasis gastric cancer tissues. The expression of microRNA-214 was significantly inversely correlated with lymph node metastasis and tumour size but had no correlation with the patient's prognosis. Ectopic expression of microRNA-214 could inhibit cell migration and invasion ability in SGC7901 and MKN45 gastric cancer cells. And knockdown of microRNA-214 significantly facilitated cell proliferation, migration and invasion in a cell-specific manner in MKN28, BGC823 and GES-1 cells. Colony stimulating factor 1 (CSF1) was identified as a target gene of microRNA-214. In summary, our data demonstrated that microRNA-214 is a promising novel biomarker for lymph node metastasis in patients with gastric cancer. And we identified that downregulation of

  16. MicroRNA deregulation in cancer cells and the tumor microenvironment

    PubMed Central

    Rupaimoole, Rajesha; Calin, George A.; Lopez-Berestein, Gabriel; Sood, Anil K.

    2015-01-01

    MicroRNAs (miRNAs) are a key component of the noncoding RNA family. The underlying mechanisms involved in the interplay between the tumor microenvironment and cancer cells involve highly dynamic factors such as hypoxia and cell types such as cancer-associated fibroblasts and macrophages. Although miRNA levels are known to be altered in cancer cells, recent evidence suggests a critical role for the tumor microenvironment in regulating miRNA biogenesis, methylation, and transcriptional changes. Here, we discuss the complex pro-tumorigenic symbiotic role between tumor cells, the tumor microenvironment, and miRNA deregulation. PMID:26865249

  17. Micro-aggregates do not influence bone marrow stromal cell chondrogenesis.

    PubMed

    Potier, E; Rivron, N C; Van Blitterswijk, C A; Ito, K

    2014-04-01

    Although bone marrow stromal cells (BMSCs) appear promising for cartilage repair, current clinical results are suboptimal and the success of BMSC-based therapies relies on a number of methodological improvements, among which is better understanding and control of their differentiation pathways. We investigated here the role of the cellular environment (paracrine vs juxtacrine signalling) in the chondrogenic differentiation of BMSCs. Bovine BMSCs were encapsulated in alginate beads, as dispersed cells or as small micro-aggregates, to create different paracrine and juxtacrine signalling conditions. BMSCs were then cultured for 21 days with TGFβ3 added for 0, 7 or 21 days. Chondrogenic differentiation was assessed at the gene (type II and X collagens, aggrecan, TGFβ, sp7) and matrix (biochemical assays and histology) levels. The results showed that micro-aggregates had no beneficial effects over dispersed cells: matrix production was similar, whereas chondrogenic marker gene expression was lower for the micro-aggregates, under all TGFβ conditions tested. This weakened chondrogenic differentiation might be explained by a different cytoskeleton organization at day 0 in the micro-aggregates. Copyright © 2014 John Wiley & Sons, Ltd.

  18. 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

  19. A Pitx2-MicroRNA Pathway Modulates Cell Proliferation in Myoblasts and Skeletal-Muscle Satellite Cells and Promotes Their Commitment to a Myogenic Cell Fate.

    PubMed

    Lozano-Velasco, Estefanía; Vallejo, Daniel; Esteban, Francisco J; Doherty, Chris; Hernández-Torres, Francisco; Franco, Diego; Aránega, Amelia Eva

    2015-09-01

    The acquisition of a proliferating-cell status from a quiescent state as well as the shift between proliferation and differentiation are key developmental steps in skeletal-muscle stem cells (satellite cells) to provide proper muscle regeneration. However, how satellite cell proliferation is regulated is not fully understood. Here, we report that the c-isoform of the transcription factor Pitx2 increases cell proliferation in myoblasts by downregulating microRNA 15b (miR-15b), miR-23b, miR-106b, and miR-503. This Pitx2c-microRNA (miRNA) pathway also regulates cell proliferation in early-activated satellite cells, enhancing Myf5(+) satellite cells and thereby promoting their commitment to a myogenic cell fate. This study reveals unknown functions of several miRNAs in myoblast and satellite cell behavior and thus may have future applications in regenerative medicine. PMID:26055324

  20. 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

  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. 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.

  3. Quantitative assay of element mass inventories in single cell biological systems with micro-PIXE

    NASA Astrophysics Data System (ADS)

    Ogrinc, Nina; Pelicon, Primož; Vavpetič, Primož; Kelemen, Mitja; Grlj, Nataša; Jeromel, Luka; Tomić, Sergej; Čolić, Miodrag; Beran, Alfred

    2013-07-01

    Elemental concentrations in micro-PIXE (Particle Induced X-ray Emission) maps of elements in biological tissue slices have been determined using auxiliary information on the sample matrix composition from EBS (Elastic Backscattering Spectroscopy) and STIM (Scanning Transmission Ion Microscopy). The thin sample approximation may be used for evaluating micro-PIXE data in cases, where X-ray absorption in the sample can be neglected and the mass of elements in a selected area can be estimated. The resulting sensitivity amounts to an impressive 10-12 g of the selected elements. Two cases are presented as examples. In the first, we determined the total mass of gold nanoparticles internalized by human monocyte-derived dendritic cells (MDDC). In the second, an inventory of the mass of elements in the micro-particulate material adsorbed at the wall of the lorica of the microzooplankton species Tintinnopsis radix has been created.

  4. Delivery of molecules into cells using localized single cell electroporation on ITO micro-electrode based transparent chip.

    PubMed

    Chen, Sheng-Chiech; Santra, Tuhin Subhra; Chang, Chia-Jung; Chen, Tsung-Ju; Wang, Pen-Cheng; Tseng, Fan-Gang

    2012-10-01

    Single cell electroporation is one of the nonviral method which successfully allows transfection of exogenous macromolecules into individual living cell. We present localized cell membrane electroporation at single-cell level by using indium tin oxide (ITO) based transparent micro-electrodes chip with inverted microscope. A focused ion beam (FIB) technique has been successfully deployed to fabricate transparent ITO micro-electrodes with submicron gaps, which can generate more intense electric field to produce very localized cell membrane electroporation. In our approach, we have successfully achieved 0.93 μm or smaller electroporation region on the cell surface to inject PI (Propidium Iodide) dye into the cell with 60 % cell viability. This experiments successfully demonstrate the cell self-recover process from the injected PI dye intensity variation. Our localized cell membrane electroporation technique (LSCMEP) not only generates reversible electroporation process but also it provides a clear optical path for potentially monitoring/tracking of drugs to deliver in single cell level.

  5. Micro segmented-flow in biochemical and cell-based assays.

    PubMed

    Clausell-Tormos, Jenifer; Merten, Christoph A

    2012-01-01

    Micro-segmented flow (e.g. in microfluidic channels, capillaries or a length of tubing) has become a promising technique in modern biology. Compared to conventional formats such as microtiter plates, sample volumes can be reduced about 1000-fold, thus allowing a massive reduction of assay costs and the use of samples available in low quantities, only (e.g. primary cells). Furthermore, assays can be highly parallelized and performed at superb spatio-temporal resolution. Here, we review the state-of-the-art in micro-segmented flow as applied in biochemical, cell- and multicellular organisms-based assays. We discuss likely future applications such as single cell / single organism proteomics and transcriptomics and point out the specific advantages and limitations compared to emulsion-based (droplet-based) approaches.

  6. Comparison of gold nanoparticle mediated photoporation: vapor nanobubbles outperform direct heating for delivering macromolecules in live cells.

    PubMed

    Xiong, Ranhua; Raemdonck, Koen; Peynshaert, Karen; Lentacker, Ine; De Cock, Ine; Demeester, Jo; De Smedt, Stefaan C; Skirtach, Andre G; Braeckmans, Kevin

    2014-06-24

    There is a great interest in delivering macromolecular agents into living cells for therapeutic purposes, such as siRNA for gene silencing. Although substantial effort has gone into designing nonviral nanocarriers for delivering macromolecules into cells, translocation of the therapeutic molecules from the endosomes after endocytosis into the cytoplasm remains a major bottleneck. Laser-induced photoporation, especially in combination with gold nanoparticles, is an alternative physical method that is receiving increasing attention for delivering macromolecules in cells. By allowing gold nanoparticles to bind to the cell membrane, nanosized membrane pores can be created upon pulsed laser illumination. Depending on the laser energy, pores are created through either direct heating of the AuNPs or by vapor nanobubbles (VNBs) that can emerge around the AuNPs. Macromolecules in the surrounding cell medium can then diffuse through the pores directly into the cytoplasm. Here we present a systematic evaluation of both photoporation mechanisms in terms of cytotoxicity, cell loading, and siRNA transfection efficiency. We find that the delivery of macromolecules under conditions of VNBs is much more efficient than direct photothermal disturbance of the plasma membrane without any noticeable cytotoxic effect. Interestingly, by tuning the laser energy, the pore size could be changed, allowing control of the amount and size of molecules that are delivered in the cytoplasm. As only a single nanosecond laser pulse is required, we conclude that VNBs are an interesting photoporation mechanism that may prove very useful for efficient high-throughput macromolecular delivery in live cells.

  7. Ion bombardment induced formation of micro-craters in plant cell envelopes

    NASA Astrophysics Data System (ADS)

    Sangyuenyongpipat, S.; Yu, L. D.; Vilaithong, T.; Brown, I. G.

    2006-01-01

    Ion beam bombardment of biological material has been recently applied for gene transfer in both plant and bacterial cells. A consistent physical mechanism for this significant result has not yet been developed. A fundamental question about the mechanism is the possible formation of pathways due to ion bombardment that are responsible for the gene transfer. We have carried out investigations of the effects of low-energy bombardment by both gaseous and metallic ion species of onion skin cells on their surface microstructure. Our experimental results reveal evidence demonstrating that the formation of micro-crater-like structures on the plant cell envelope surface is a general phenomenon consequent to ion bombardment, no matter what ion species, under certain ion beam conditions. The micro-craters are about 0.1-1 μm in size (diameter) and a few tens of nanometers in depth. The micro-crater formation process seems to be unrelated to the chemical composition of and rapid water evaporation from the cell envelope, but is associated with the special microstructure of the cell wall.

  8. 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.

  9. 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

  10. Epithelial microRNAs regulate gut mucosal immunity via epithelium-T cell crosstalk.

    PubMed

    Biton, Moshe; Levin, Avi; Slyper, Michal; Alkalay, Irit; Horwitz, Elad; Mor, Hagar; Kredo-Russo, Sharon; Avnit-Sagi, Tali; Cojocaru, Gady; Zreik, Farid; Bentwich, Zvi; Poy, Matthew N; Artis, David; Walker, Michael D; Hornstein, Eran; Pikarsky, Eli; Ben-Neriah, Yinon

    2011-03-01

    Colonic homeostasis entails epithelium-lymphocyte cooperation, yet many participants in this process are unknown. We show here that epithelial microRNAs mediate the mucosa-immune system crosstalk necessary for mounting protective T helper type 2 (T(H)2) responses. Abolishing the induction of microRNA by gut-specific deletion of Dicer1 (Dicer1(Δgut)), which encodes an enzyme involved in microRNA biogenesis, deprived goblet cells of RELMβ, a key T(H)2 antiparasitic cytokine; this predisposed the host to parasite infection. Infection of Dicer1(Δgut) mice with helminths favored a futile T(H)1 response with hallmarks of inflammatory bowel disease. Interleukin 13 (IL-13) induced the microRNA miR-375, which regulates the expression of TSLP, a T(H)2-facilitating epithelial cytokine; this indicated a T(H)2-amplification loop. We found that miR-375 was required for RELMβ expression in vivo; miR-375-deficient mice had significantly less intestinal RELMβ, which possibly explains the greater susceptibility of Dicer1(Δgut) mice to parasites. Our findings indicate that epithelial microRNAs are key regulators of gut homeostasis and mucosal immunity.

  11. MicroRNA Regulates Hepatocytic Differentiation of Progenitor Cells by Targeting YAP1.

    PubMed

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

    2016-05-01

    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 overexpression 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. Stem Cells 2016;34:1284-1296.

  12. 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

  13. Development of a micro cell compression stimulator for evaluating real-time cellular responses

    NASA Astrophysics Data System (ADS)

    Nakashima, Y.; Yang, Y.; Minami, K.

    2012-05-01

    This paper presents a micro cell compression stimulator for evaluating real-time cellular responses to compression stimuli. The device was produced by a micro three-dimensional structure fabrication process using multiple exposures to the photoresist. The device consists of a pressure inlet port, cell inlet ports, a gasket, microchannels, cell culture chambers, and a diaphragm on the culture chamber for applying compressive pressure to cells. Compression stimuli applied to the cells can be controlled by regulating the expansion of the diaphragm via a pressure control. The device permits the observation of cellular responses to compressive pressure in real time because it is made of transparent materials and stimulates the cells without deforming the cell culture surface, when observed by optical microscopy. We demonstrated the validity of the fabrication process, evaluated the performance of the fabricated device, and compared the experimental results with the FEM structural analysis results. We found through operational testing that the diaphragm was deformed quickly by applying negative/positive pressure and that the diaphragm displacement became larger with increasing applied pressure. These results indicate that this device can be used to control the intensity and the cell stimulus profile by regulating the applied pressure. In all cases, the cellular deformation during compression stimulus was successfully observed in real time using an optical microscope. The device is expected to facilitate the control of stem cell differentiation and the clarification of cellular mechanoreceptor mechanisms and signal transduction pathways.

  14. Study of dendritic cell migration using micro-fabrication.

    PubMed

    Vargas, Pablo; Chabaud, Mélanie; Thiam, Hawa-Racine; Lankar, Danielle; Piel, Matthieu; Lennon-Dumenil, Ana-Maria

    2016-05-01

    Cell migration is a hallmark of dendritic cells (DCs) function. It is needed for DCs to scan their environment in search for antigens as well as to reach lymphatic organs in order to trigger T lymphocyte's activation. Such interaction leads to tolerance in the case of DCs migrating under homeostatic conditions or to immunity in the case of DCs migrating upon encounter with pathogen-associated molecular patterns. Cell migration is therefore essential for DCs to transfer information from peripheral tissues to lymphoid organs, thereby linking innate to adaptive immunity. This stresses the need to unravel the molecular mechanisms involved. However, the tremendous complexity of the tissue microenvironment as well as the limited spatio-temporal resolution of in vivo imaging techniques has made this task difficult. To bypass this problem, we have developed microfabrication-based experimental tools that are compatible with high-resolution imaging. Here, we will discuss how such devices can be used to study DC migration under controlled conditions that mimic their physiological environment in a robust quantitative manner.

  15. 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.

  16. Trash or Treasure: extracellular microRNAs and cell-to-cell communication.

    PubMed

    Kosaka, Nobuyoshi; Yoshioka, Yusuke; Hagiwara, Keitaro; Tominaga, Naoomi; Katsuda, Takeshi; Ochiya, Takahiro

    2013-01-01

    Circulating RNAs in human body fluids are promising candidates for diagnostic purposes. However, the biological significance of circulating RNAs remains elusive. Recently, small non-coding RNAs, microRNAs (miRNAs), were isolated from multiple human body fluids, and these "circulating miRNAs" have been implicated as novel disease biomarkers. Concurrently, miRNAs were also identified in the extracellular space associated with extracellular vesicles (EVs), which are small membrane vesicles secreted from various types of cells. The function of these secreted miRNAs has been revealed in several papers. Circulating miRNAs have been experimentally found to be associated with EVs; however, other types of extracellular miRNAs were also described. This review discusses studies related to extracellular miRNAs, including circulating miRNAs and secreted miRNAs, to highlight the importance of studying not only secreted miRNAs, but also circulating miRNAs to determine the contribution of extracellular miRNAs especially in cancer development.

  17. 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

  18. Deep sequencing and proteomic analysis of the microRNA-induced silencing complex in human red blood cells.

    PubMed

    Azzouzi, Imane; Moest, Hansjoerg; Wollscheid, Bernd; Schmugge, Markus; Eekels, Julia J M; Speer, Oliver

    2015-05-01

    During maturation, erythropoietic cells extrude their nuclei but retain their ability to respond to oxidant stress by tightly regulating protein translation. Several studies have reported microRNA-mediated regulation of translation during terminal stages of erythropoiesis, even after enucleation. In the present study, we performed a detailed examination of the endogenous microRNA machinery in human red blood cells using a combination of deep sequencing analysis of microRNAs and proteomic analysis of the microRNA-induced silencing complex. Among the 197 different microRNAs detected, miR-451a was the most abundant, representing more than 60% of all read sequences. In addition, miR-451a and its known target, 14-3-3ζ mRNA, were bound to the microRNA-induced silencing complex, implying their direct interaction in red blood cells. The proteomic characterization of endogenous Argonaute 2-associated microRNA-induced silencing complex revealed 26 cofactor candidates. Among these cofactors, we identified several RNA-binding proteins, as well as motor proteins and vesicular trafficking proteins. Our results demonstrate that red blood cells contain complex microRNA machinery, which might enable immature red blood cells to control protein translation independent of de novo nuclei information. PMID:25681748

  19. 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

  20. 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

  1. 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.

  2. 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

  3. A precious-metal free micro fuel cell accumulator

    NASA Astrophysics Data System (ADS)

    Bretthauer, C.; Müller, C.; Reinecke, H.

    2011-05-01

    In recent years, integrated fuel cell (FC) type primary and secondary batteries attracted a great deal of attention as integrated on-chip power sources due to their high theoretical power densities. Unfortunately, the costs of these devices have been rather high. This is partially due to the involved clean-room processes, but also due to the fact that these devices generally rely on expensive precious-metals such as Pd and Pt. Therefore we developed a novel integrated FC type accumulator that is based on non-precious-metals only. The key component of the presented accumulator is its alkaline polymer electrolyte membrane that allows not only the usage of a low-cost AB5 type hydrogen storage electrode, but also the usage of La0.6Ca0.4CoO3 as a precious-metal free bifunctional catalyst for the air-breathing electrode. Additionally the presented design requires only comparatively few cleanroom processes which further reduces the overall production costs. Although abdicating precious-metals, the presented accumulator shows an open circuit voltage of 0.81 V and a maximum power density of 0.66 mW cm-2 which is comparable or even superior to former precious-metal based cells.

  4. 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

  5. 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

  6. Micro-fabricated fluorescence-activated cell sorter.

    PubMed

    Cho, Sung Hwan; Chen, Chun H; Tsai, Frank S; Lo, Yu-Hwa

    2009-01-01

    We demonstrate a high sensitivity, high throughput microfabricated cell sorting device with the integrated piezoelectric actuator and optofluidic waveguide on a chip. For automated sorting, field-programmable-gate-array (FPGA) embedded real time control loop system is built. The sorting is performed under high flow rate ( approximately 10 cm/sec), and the sorting system can achieve a high throughput (> 1kHz) with high purity. Moreover, to enhance its sensitivity, Teflon AF coated liquid core waveguide (LCW) structure is demonstrated. Teflon AF has a lower refractive index (n=1.31) than water (n=1.33) and forms the cladding layer of the LCW. Incident light is confined and guided along the Teflon AF coated fluidic channel, and interact with samples flowing along the same channel. This enables flexible device design and gives high sensitivity to the fluorescence detection system. The preliminary results demonstrate sorting fluorescent beads at a sorting efficiency of approximately 70% with no false sorting.

  7. 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.

  8. 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.

  9. Identifying mRNA targets of microRNA dysregulated in cancer: with application to clear cell Renal Cell Carcinoma

    PubMed Central

    2010-01-01

    Background MicroRNA regulate mRNA levels in a tissue specific way, either by inducing degradation of the transcript or by inhibiting translation or transcription. Putative mRNA targets of microRNA identified from seed sequence matches are available in many databases. However, such matches have a high false positive rate and cannot identify tissue specificity of regulation. Results We describe a simple method to identify direct mRNA targets of microRNA dysregulated in cancers from expression level measurements in patient matched tumor/normal samples. The word "direct" is used here in a strict sense to: a) represent mRNA which have an exact seed sequence match to the microRNA in their 3'UTR, b) the seed sequence match is strictly conserved across mouse, human, rat and dog genomes, c) the mRNA and microRNA expression levels can distinguish tumor from normal with high significance and d) the microRNA/mRNA expression levels are strongly and significantly anti-correlated in tumor and/or normal samples. We apply and validate the method using clear cell Renal Cell Carcinoma (ccRCC) and matched normal kidney samples, limiting our analysis to mRNA targets which undergo degradation of the mRNA transcript because of a perfect seed sequence match. Dysregulated microRNA and mRNA are first identified by comparing their expression levels in tumor vs normal samples. Putative dysregulated microRNA/mRNA pairs are identified from these using seed sequence matches, requiring that the seed sequence be conserved in human/dog/rat/mouse genomes. These are further pruned by requiring a strong anti-correlation signature in tumor and/or normal samples. The method revealed many new regulations in ccRCC. For instance, loss of miR-149, miR-200c and mir-141 causes gain of function of oncogenes (KCNMA1, LOX), VEGFA and SEMA6A respectively and increased levels of miR-142-3p, miR-185, mir-34a, miR-224, miR-21 cause loss of function of tumor suppressors LRRC2, PTPN13, SFRP1, ERBB4, and (SLC12A1, TCF

  10. 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.

  11. Small-sized dichroic atomic vapor laser lock

    NASA Astrophysics Data System (ADS)

    Lee, Changmin; Iwata, G. Z.; Corsini, E.; Higbie, J. M.; Knappe, S.; Ledbetter, M. P.; Budker, D.

    2011-04-01

    Two, lightweight diode laser frequency stabilization systems designed for experiments in the field are described. A significant reduction in size and weight in both models supports the further miniaturization of measurement devices in the field. Similar to a previous design, magnetic field lines are contained within a magnetic shield enclosing permanent magnets and a Rb cell, so that these dichroic atomic vapor laser lock (DAVLL) systems may be used for magnetically sensitive instruments. The mini-DAVLL system (49 mm long) uses a vapor cell (20 mm long) and does not require cell heaters. An even smaller micro-DAVLL system (9 mm long) uses a microfabricated cell (3 mm square) and requires heaters. These new systems show no degradation in performance with regard to previous designs while considerably reducing dimensions.

  12. 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

  13. Manipulating biological agents and cells in micro-scale volumes for applications in medicine.

    PubMed

    Tasoglu, Savas; Gurkan, Umut Atakan; Wang, Shuqi; Demirci, Utkan

    2013-07-01

    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.

  14. 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

  15. 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.

  16. Investigation of Micro- and Macro-Scale Transport Processes for Improved Fuel Cell Performance

    SciTech Connect

    Gu, Wenbin

    2014-08-29

    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.

  17. 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

  18. Application of micro-porous polycarbonate membranes in dye-sensitized solar cells: Cell performance and long-term stability

    NASA Astrophysics Data System (ADS)

    Lue, Shingjiang Jessie; Lo, Pei Wen; Hung, Ling-Yung; Tung, Yung Liang

    This research investigates the cell performance and long-term stability of dye-sensitized solar cells (DSSCs) containing micro-porous polycarbonate (PC) film as the frame work material to stabilize the electrolyte solution. The track-etched PC film has cylindrical pore geometry, which is beneficial for ion transport in the electrolyte trapped inside the PC film. The photovoltaic efficiency of the DSSC with 0.2-μm PC membrane is 5.75 ± 0.73% under irradiation of 100 mW cm -2, which is slightly lower than that (6.34 ± 0.44%) of cells without PC film. The differences in fill factor and open-circuit voltage between the DSSCs with and without PC film are not statistically significant. The long-term cell performance is carried out at continuous illumination of 100 mW cm -2 (1 sun) and in darkness at 60 °C for up to 1000 h. There is no significant efficiency difference between the cells with and without PC film in light soaking (4.33% vs. 4.52%) for 960 h. In darkness, however, the cells with PC film demonstrate much higher efficiency (at 2.37%) than cells without PC (0.85%) after 1000 h. The improved long-term efficiency data and the higher percentage of working cells confirm the superior lifetime and performance using the micro-porous PC film.

  19. 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.

  20. microRNA-103/107 family regulates multiple epithelial stem cell characteristics

    PubMed Central

    Peng, Han; Park, Jong Kook; Katsnelson, Julia; Kaplan, Nihal; Yang, Wending; Getsios, Spiro; Lavker, Robert M.

    2015-01-01

    The stem cell niche is thought to affect cell cycle quiescence, proliferative capacity and communication between stem cells and their neighbors. How these activities are controlled is not completely understood. Here we define a microRNA family (miRs-103/107) preferentially expressed in the stem cell-enriched limbal epithelium that regulates and integrates these stem cell characteristics. miRs-103/107 target the ribosomal kinase p90RSK2, thereby arresting cells in G0/G1 and contributing to a slow-cycling phenotype. Furthermore, miRs-103/107 increase the proliferative capacity of keratinocytes by targeting Wnt3a, which enhances Sox 9 and YAP 1 levels and thus promotes a stem cell phenotype. This miRNA family also regulates keratinocyte cell-cell communication by targeting: (i) the scaffolding protein NEDD9, preserving E-cadherin-mediated cell adhesion; and (ii) the tyrosine phosphatase PTPRM, which negatively regulates connexin 43-based gap junctions. We propose that such regulation of cell communication and adhesion molecules maintains the integrity of the stem cell niche ultimately preserving self-renewal, a hallmark of epithelial stem cells. PMID:25639731

  1. 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.

  2. 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

  3. 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.

  4. 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

  5. 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

  6. Topographical effects on fiber-mediated microRNA delivery to control oligodendroglial precursor cells development

    PubMed Central

    Diao, Hua Jia; Low, Wei Ching; Lu, Q. Richard; Chew, Sing Yian

    2016-01-01

    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

  7. 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.

  8. 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.

  9. 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

  10. 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

  11. Endocrine disrupters, microRNAs, and primordial germ cells: a dangerous cocktail.

    PubMed

    Brieño-Enríquez, Miguel Angel; Larriba, Eduardo; Del Mazo, Jesús

    2016-09-15

    Endocrine-disrupting chemicals (EDCs) are environmental pollutants that may change the homeostasis of the endocrine system, altering the differentiation of germ cells with consequences for reproduction. In mammals, germ cell differentiation begins with primordial germ cells (PGCs) during embryogenesis. Primordial germ cell development and gametogenesis are genetically regulated processes, in which the posttranscriptional gene regulation could be mediated by small noncoding RNAs (sncRNAs) such as microRNAs (miRNAs). Here, we review the deleterious effects of exposure during fetal life to EDCs mediated by deregulation of ncRNAs, and specifically miRNAs on PGC differentiation. Moreover, the environmental stress induced by exposure to some EDCs during the embryonic window of development could trigger reproductive dysfunctions transgenerationally transmitted by epigenetic mechanisms with the involvement of miRNAs expressed in germ line cells. PMID:27521771

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Vapor Explosions

    NASA Astrophysics Data System (ADS)

    Berthoud, Georges

    A vapor explosion results from the rapid and intense heat transfer that may follow contact between a hot liquid and a cold, more volatile one. Because it can happen during severe-accident sequences of a nuclear power plan, that is, when a large part of the core is molten, vapor explosions have been widely studied. The different sequences of a vapor explosion are presented, including premixing, triggering, propagation, and expansion. Typical experimental results are also analyzed to understand the involved physics. Then the different physics involved in the sequences are addressed, as well as the present experimental program.

  17. 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

  18. MR-05GLIOMA STEM CELL SPECIFIC microRNA-mRNA INTERACTION NETWORK

    PubMed Central

    Singh, Sanjay; Burrell, Kelly; Alamsahebpour, Amir; Koch, Elizabeth; Agnihotri, Sameer; Gumin, Joy; Sulman, Erik; Lang, Frederick; Wouters, Bradley; Aldape, Kenneth; Zadeh, Gelareh

    2014-01-01

    microRNAs have been shown to have oncogenic or tumor suppressor function in glioblastoma (GBM). It has been postulated that there exists an extensive microRNA-mediated RNA-RNA interaction network in GBMs utilizing systems biology approach supporting a competitive endogenous RNA (ce-RNA). MicroRNAs have functional relevance in the regulation of critical genes and pathways implicated in the maintenance of glioma stem cell (GSC) properties. To address this, we have applied biochemical methods to establish direct miRNA-mRNA interaction network relevant and specific to GSCs. To avoid inclusion of the inherent bias of miRNA-target prediction algorithms, we have generated an unbiased global miRNA mediated RNA-RNA interactome by performing RNA-sequencing all RNA species (small and large RNAs) isolated from AGO2-microRNA-induced silencing complex (miRISC) of GSCs and normal human neural stem cells (hNSCs). Additionally, we have also established this interactome after exposure of GSCs and normal hNSCs to hypoxia, a key tumor micro-environmental factor that is known to be pivotal in generating GBM heterogeneity. In all, three independent GSC lines and one NSC line were profiled, and results compared with each other. miRNA-mRNA interaction nodes were determined by RNA read counts from RNA-seq data and combinations of miRNA target prediction softwares. The rank order list of miRNA-mRNA interaction nodes generated from RNA sequence reads reveals that enrichment of specific RNAs in functional AGO2-miRISC is not a direct function of their relative abundance in cells, thus this biochemically generated interactome is distinct from that generated by bioinformatics tools. Our data shows that MYC as one of the key networks targetted by microRNAs specifically in GSCs under hypoxic conditions. We demonstrate that scope and influence of GSC specific miRNA-mRNA network and specific nodes of this interactome varies with hypoxia and tumor region in GBMs

  19. 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

  20. 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.

  1. Effect of microRNA-203 on tumor growth in human hypopharyngeal squamous cell carcinoma.

    PubMed

    Wang, Ru; Fang, Jugao; Ma, Hongzhi; Feng, Lin; Lian, Meng; Yang, Fan; Wang, Haizhou; Wang, Qi; Chen, Xiaohong

    2015-07-01

    MicroRNAs (MiRNAs) have been recognized to regulate cancer initiation and progression in carcinogenesis as either oncogenes or tumor suppressor genes, but their role in hypopharyngeal cancer development is not clearly defined. To determine whether miRNA-203 can promote tumor growth in human hypopharyngeal squamous cell carcinoma, we conducted experiments on the functional study of miRNA-203 and identification of miRNA-203 regulated target genes in hypopharyngeal cancer cells. We found that cell proliferation and cell colony-forming increased more in the miRNA-203 up-regulated cancer cells than in the negative control cancer cells. Up-regulation of miRNA-203 accelerated cell cycle progression in hypopharyngeal cancer cells. TP63 and B3GNT5 mRNAs were identified and validated as targets of miRNA-203. However, transwell assay and wound scratch assay showed that miRNA-203 did not involve in invasion and metastasis in hypopharyngeal cancer cells. According to the results, we conclude that miRNA-203 can promote tumor growth in human hypopharyngeal squamous cell carcinoma. These results provide the convincing evidence for the first time that up-regulation of miRNA-203 contributes to the malignancy of hypopharyngeal squamous cell carcinoma, possibly through down-regulating TP63 and B3GNT5.

  2. Inhibition of Gastric Tumor Cell Growth Using Seed-targeting LNA as Specific, Long-lasting MicroRNA Inhibitors.

    PubMed

    Staedel, Cathy; Varon, Christine; Nguyen, Phu Hung; Vialet, Brune; Chambonnier, Lucie; Rousseau, Benoît; Soubeyran, Isabelle; Evrard, Serge; Couillaud, Franck; Darfeuille, Fabien

    2015-07-07

    MicroRNAs regulate eukaryotic gene expression upon pairing onto target mRNAs. This targeting is influenced by the complementarity between the microRNA "seed" sequence at its 5' end and the seed-matching sequences in the mRNA. Here, we assess the efficiency and specificity of 8-mer locked nucleic acid (LNA)-modified oligonucleotides raised against the seeds of miR-372 and miR-373, two embryonic stem cell-specific microRNAs prominently expressed in the human gastric adenocarcinoma AGS cell line. Provided that the pairing is perfect over all the eight nucleotides of the seed and starts at nucleotide 2 or 1 at the microRNA 5' end, these short LNAs inhibit miR-372/373 functions and derepress their common target, the cell cycle regulator LATS2. They decrease cell proliferation in vitro upon either transfection at nanomolar concentrations or unassisted delivery at micromolar concentrations. Subcutaneously delivered LNAs reduce tumor growth of AGS xenografts in mice, upon formation of a stable, specific heteroduplex with the targeted miR-372 and -373 and LATS2 upregulation. Their therapeutic potential is confirmed in fast-growing, miR-372-positive, primary human gastric adenocarcinoma xenografts in mice. Thus, microRNA silencing by 8-mer seed-targeting LNAs appears a valuable approach for both loss-of-function studies aimed at elucidating microRNA functions and for microRNA-based therapeutic strategies.

  3. MicroRNA-944 Affects Cell Growth by Targeting EPHA7 in Non-Small Cell Lung Cancer

    PubMed Central

    Liu, Minxia; Zhou, Kecheng; Cao, Yi

    2016-01-01

    MicroRNAs (miRNAs) have critical roles in lung tumorigenesis and development. To determine aberrantly expressed miRNAs involved in non-small cell lung cancer (NSCLC) and investigate pathophysiological functions and mechanisms, we firstly carried out small RNA deep sequencing in NSCLC cell lines (EPLC-32M1, A549 and 801D) and a human immortalized cell line 16HBE, we then studied miRNA function by cell proliferation and apoptosis. cDNA microarray, luciferase reporter assay and miRNA transfection were used to investigate interaction between the miRNA and target gene. miR-944 was significantly down-regulated in NSCLC and had many putative targets. Moreover, the forced expression of miR-944 significantly inhibited the proliferation of NSCLC cells in vitro. By integrating mRNA expression data and miR-944-target prediction, we disclosed that EPHA7 was a potential target of miR-944, which was further verified by luciferase reporter assay and microRNA transfection. Our data indicated that miR-944 targets EPHA7 in NSCLC and regulates NSCLC cell proliferation, which may offer a new mechanism underlying the development and progression of NSCLC. PMID:27681722

  4. 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.

  5. 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.

  6. 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

  7. MicroRNA-566 activates EGFR signaling and its inhibition sensitizes glioblastoma cells to nimotuzumab

    PubMed Central

    2014-01-01

    Background Epidermal growth factor receptor (EGFR) is amplified in 40% of human glioblastomas. However, most glioblastoma patients respond poorly to anti-EGFR therapy. MicroRNAs can function as either oncogenes or tumor suppressor genes, and have been shown to play an important role in cancer cell proliferation, invasion and apoptosis. Whether microRNAs can impact the therapeutic effects of EGFR inhibitors in glioblastoma is unknown. Methods miR-566 expression levels were detected in glioma cell lines, using real-time quantitative RT-PCR (qRT-PCR). Luciferase reporter assays and Western blots were used to validate VHL as a direct target gene of miR-566. Cell proliferation, invasion, cell cycle distribution and apoptosis were also examined to confirm whether miR-566 inhibition could sensitize anti-EGFR therapy. Results In this study, we demonstrated that miR-566 is up-regulated in human glioma cell lines and inhibition of miR-566 decreased the activity of the EGFR pathway. Lentiviral mediated inhibition of miR-566 in glioblastoma cell lines significantly inhibited cell proliferation and invasion and led to cell cycle arrest in the G0/G1 phase. In addition, we identified von Hippel-Lindau (VHL) as a novel functional target of miR-566. VHL regulates the formation of the β-catenin/hypoxia-inducible factors-1α complex under miR-566 regulation. Conclusions miR-566 activated EGFR signaling and its inhibition sensitized glioblastoma cells to anti-EGFR therapy. PMID:24650032

  8. 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.

  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. 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

  11. 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.

  12. 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

    2016-07-01

    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.

  13. 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.

  14. 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.

  15. 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

  16. 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

  17. 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.

  18. 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.

  19. Subtypes of asthma defined by epithelial cell expression of messenger RNA and microRNA.

    PubMed

    Woodruff, Prescott G

    2013-12-01

    Human asthma can be subcategorized in several ways, but one powerful approach is to subtype asthma on the basis of underlying cellular and molecular mechanisms. Groups of patients with a disease that share a common underlying biology are termed an "endotype." Endotypes of asthma have been studied at both the cellular level (by cytological examination of induced sputum) and, increasingly, at the molecular level. Genome-wide analyses of mRNA expression within the lung have been useful in the identification of molecular endotypes of asthma and point to protein biomarkers of those endotypes that can be measured in the blood. More recently, studies of microRNA expression in airway epithelial cells in asthma have identified additional candidate biomarkers of asthma endotypes. One potentially valuable property of microRNAs is that they can also be measured in extracellular fluids and therefore have the potential to serve directly as noninvasively measured biomarkers.

  20. Thin film solar cells with Si nanocrystallites embedded in amorphous intrinsic layers by hot-wire chemical vapor deposition.

    PubMed

    Park, Seungil; Parida, Bhaskar; Kim, Keunjoo

    2013-05-01

    We investigated the thin film growths of hydrogenated silicon by hot-wire chemical vapor deposition with different flow rates of SiH4 and H2 mixture ambient and fabricated thin film solar cells by implementing the intrinsic layers to SiC/Si heterojunction p-i-n structures. The film samples showed the different infrared absorption spectra of 2,000 and 2,100 cm(-1), which are corresponding to the chemical bonds of SiH and SiH2, respectively. The a-Si:H sample with the relatively high silane concentration provides the absorption peak of SiH bond, but the microc-Si:H sample with the relatively low silane concentration provides the absorption peak of SiH2 bond as well as SiH bond. Furthermore, the microc-Si:H sample showed the Raman spectral shift of 520 cm(-1) for crystalline phase Si bonds as well as the 480 cm(-1) for the amorphous phase Si bonds. These bonding structures are very consistent with the further analysis of the long-wavelength photoconduction tail and the formation of nanocrystalline Si structures. The microc-Si:H thin film solar cell has the photovoltaic behavior of open circuit voltage similar to crystalline silicon thin film solar cell, indicating that microc-Si:H thin film with the mixed phase of amorphous and nanocrystalline structures show the carrier transportation through the channel of nanocrystallites.

  1. 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

  2. microRNA-21 is upregulated in malignant melanoma and influences apoptosis of melanocytic cells.

    PubMed

    Satzger, Imke; Mattern, Anika; Kuettler, Uta; Weinspach, Dirk; Niebuhr, Margarete; Kapp, Alexander; Gutzmer, Ralf

    2012-07-01

    Overexpression of microRNA-21 (miR-21) has been observed in various cancer types, but little is known about the role of miR-21 in melanoma. In this study, we demonstrate that levels of miR-21 are significantly increased in primary melanoma tissues as compared to benign nevi and in human melanoma cell lines as compared to melanocytic cell preparations. We show that downregulation of miR-21 in melanoma cell lines with high endogenous miR-21 expression induced apoptosis, whereas proliferation was not significantly altered. Upregulation of miR-21 in melanocytes resulted in increased proliferation and decreased apoptosis. However, in the MEWO melanoma cells with low endogenous miR-21 expression, upregulation of miR-21 had no functional effects. These findings indicate a potential pathogenetic role of miR-21 upregulation in a subgroup of melanomas.

  3. 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

  4. 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

  5. A versatile automated platform for micro-scale cell stimulation experiments.

    PubMed

    Sinha, Anupama; Jebrail, Mais J; Kim, Hanyoup; Patel, Kamlesh D; Branda, Steven S

    2013-08-06

    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

  6. 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

  7. 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.

  8. 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

  9. 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

  10. MicroRNA-155 influences B-cell function through PU.1 in rheumatoid arthritis

    PubMed Central

    Alivernini, Stefano; Kurowska-Stolarska, Mariola; Tolusso, Barbara; Benvenuto, Roberta; Elmesmari, Aziza; Canestri, Silvia; Petricca, Luca; Mangoni, Antonella; Fedele, Anna Laura; Di Mario, Clara; Gigante, Maria Rita; Gremese, Elisa; McInnes, Iain B.; Ferraccioli, Gianfranco

    2016-01-01

    MicroRNA-155 (miR-155) is an important regulator of B cells in mice. B cells have a critical role in the pathogenesis of rheumatoid arthritis (RA). Here we show that miR-155 is highly expressed in peripheral blood B cells from RA patients compared with healthy individuals, particularly in the IgD-CD27- memory B-cell population in ACPA+ RA. MiR-155 is highly expressed in RA B cells from patients with synovial tissue containing ectopic germinal centres compared with diffuse synovial tissue. MiR-155 expression is associated reciprocally with lower expression of PU.1 at B-cell level in the synovial compartment. Stimulation of healthy donor B cells with CD40L, anti-IgM, IL-21, CpG, IFN-α, IL-6 or BAFF induces miR-155 and decreases PU.1 expression. Finally, inhibition of endogenous miR-155 in B cells of RA patients restores PU.1 and reduces production of antibodies. Our data suggest that miR-155 is an important regulator of B-cell activation in RA. PMID:27671860

  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. 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

  13. 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

  14. Endothelial cell colonization and angiogenic potential of combined nano- and micro-fibrous scaffolds for bone tissue engineering.

    PubMed

    Santos, Marina I; Tuzlakoglu, Kadriye; Fuchs, Sabine; Gomes, Manuela E; Peters, Kirsten; Unger, Ronald E; Piskin, Erhan; Reis, Rui L; Kirkpatrick, C James

    2008-11-01

    Presently the majority of tissue engineering approaches aimed at regenerating bone relies only on post-implantation vascularization. Strategies that include seeding endothelial cells (ECs) on biomaterials and promoting their adhesion, migration and functionality might be a solution for the formation of vascularized bone. Nano/micro-fiber-combined scaffolds have an innovative structure, inspired by extracellular matrix (ECM) that combines a nano-network, aimed to promote cell adhesion, with a micro-fiber mesh that provides the mechanical support. In this work we addressed the influence of this nano-network on growth pattern, morphology, inflammatory expression profile, expression of structural proteins, homotypic interactions and angiogenic potential of human EC cultured on a scaffold made of a blend of starch and poly(caprolactone). The nano-network allowed cells to span between individual micro-fibers and influenced cell morphology. Furthermore, on nano-fibers as well as on micro-fibers ECs maintained the physiological expression pattern of the structural protein vimentin and PECAM-1 between adjacent cells. In addition, ECs growing on the nano/micro-fiber-combined scaffold were sensitive to pro-inflammatory stimulus. Under pro-angiogenic conditions in vitro, the ECM-like nano-network provided the structural and organizational stability for ECs' migration and organization into capillary-like structures. The architecture of nano/micro-fiber-combined scaffolds elicited and guided the 3D distribution of ECs without compromising the structural requirements for bone regeneration.

  15. Development of high-bandgap AlGaInP solar cells grown by organometallic vapor-phase epitaxy

    DOE PAGES

    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

  16. 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

  17. 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.

  18. 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

  19. MicroRNA-205 inhibits renal cells apoptosis via targeting CMTM4

    PubMed Central

    Zhang, Hongxia; Zhang, Xiaoning; Yuan, Xiaoying; Wang, Linna; Xiao, Ying

    2015-01-01

    Objective(s): MicroRNAs (miRNAs) are small non-coding RNA molecules that regulate gene expression. They have important roles in kidney development, homeostasis and disease, and participate in the onset and progression of tubulointerstitial sclerosis and end-stage glomerular lesions that occur in various forms of chronic kidney disease (CKD). In the present study, we elucidated the role of microRNA 205 (miR-205) in cisplatin-induced renal cell apoptosis and explored the molecular mechanisms. Materials and Methods: The chronic interstitial nephropathy rat model was induced, and the miRNA expression profile in the kidney cells from rats with CKD was screened. Cisplatin-induced apoptosis in normal renal HK-2 cells was evaluated using flow cytometry, and regulation of miR-205 on target gene was validated using luciferase assay, western blot and real time PCR assays. Results: We found that miR-205 expression was significantly decreased in the cells from kidney of CKD rat (P<0.01). Our data showed that when miR-205 was overexpressed or silenced using the mimic or inhibitor, the percentages of apoptotic cells were suppressed or increased significantly (P<0.05), respectively. Moreover, we have identified CMTM4 gene, which is involved in cell proliferation and apoptosis, as a novel target for miR-205. In addition, miR-205 could inhibit apoptosis by binding to the 3’UTR of CMTM4 mRNA and inhibiting its transcriptional activity. Conclusion: This study elucidated that miR-205 plays an important role in the regulation of apoptosis in renal cells, suggesting a potential therapeutic target to hinder CKD development. PMID:26730338

  20. 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

  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. T Cell Interstitial Migration: Motility Cues from the Inflamed Tissue for Micro- and Macro-Positioning

    PubMed Central

    Gaylo, Alison; Schrock, Dillon C.; Fernandes, Ninoshka R. J.; Fowell, Deborah J.

    2016-01-01

    Effector T cells exit the inflamed vasculature into an environment shaped by tissue-specific structural configurations and inflammation-imposed extrinsic modifications. Once within interstitial spaces of non-lymphoid tissues, T cells migrate in an apparent random, non-directional, fashion. Efficient T cell scanning of the tissue environment is essential for successful location of infected target cells or encounter with antigen-presenting cells that activate the T cell’s antimicrobial effector functions. The mechanisms of interstitial T cell motility and the environmental cues that may promote or hinder efficient tissue scanning are poorly understood. The extracellular matrix (ECM) appears to play an important scaffolding role in guidance of T cell migration and likely provides a platform for the display of chemotactic factors that may help to direct the positioning of T cells. Here, we discuss how intravital imaging has provided insight into the motility patterns and cellular machinery that facilitates T cell interstitial migration and the critical environmental factors that may optimize the efficiency of effector T cell scanning of the inflamed tissue. Specifically, we highlight the local micro-positioning cues T cells encounter as they migrate within inflamed tissues, from surrounding ECM and signaling molecules, as well as a requirement for appropriate long-range macro-positioning within distinct tissue compartments or at discrete foci of infection or tissue damage. The central nervous system (CNS) responds to injury and infection by extensively remodeling the ECM and with the de novo generation of a fibroblastic reticular network that likely influences T cell motility. We examine how inflammation-induced changes to the CNS landscape may regulate T cell tissue exploration and modulate function. PMID:27790220

  3. MicroRNA-15a/16 Regulates Apoptosis of Lung Epithelial Cells After Oxidative Stress

    PubMed Central

    Cao, Yong; Zhang, Duo; Moon, Hyung-Geun; Lee, Heedoo; Haspel, Jeffrey A; Hu, Kebin; Xie, Lixin; Jin, Yang

    2016-01-01

    Lung epithelial cell apoptosis is an important feature of hyperoxia-induced lung injury. The death receptor–associated extrinsic pathway and mitochondria-associated intrinsic pathway both mediate the development of lung epithelial cell apoptosis. Despite decades of research, molecular mechanisms of hyperoxia-induced epithelial cell apoptosis remain incompletely understood. Here, we report a novel regulatory paradigm in response to hyperoxia-associated oxidative stress. Hyperoxia markedly upregulated microRNA (miR)-15a/16 levels in lung epithelial cells, bronchoalveolar lavage fluid (BALF) and lung tissue. This effect was mediated by hyperoxia-induced reactive oxygen species. Functionally, miR-15a/16 inhibitors induced caspase-3–mediated lung epithelial cell apoptosis, in the presence of hyperoxia. MiR-15a/16 inhibitors robustly enhanced FADD level and downregulated Bcl-2 expression. Consistently, cleaved caspase-8 and -9 were highly induced in the miR-15a/16–deficient cells, after hyperoxia. Using airway epithelial cell–specific, miR-15a/16–/– mice, we found that Bcl-2 was significantly reduced in lung epithelial cells in vivo after hyperoxia. In contrast, caspase-3, caspase-8 and Bcl-2–associated death promoter (BAD) were highly elevated in the miR-15a/16–/– epithelial cells in vivo. Interestingly, in lung epithelial malignant cells, rather than benign cells, deletion of miR-15a/16 prevented apoptosis. Furthermore, deletion of miR-15a/16 in macrophages also prohibited apoptosis, which is the opposite of what we have found in normal lung epithelial cells. Taken together, our data suggested that miR-15a/16 may exert differential roles in different cell types. MiR-15a/16 deficiency results in lung epithelial cell apoptosis in response to hyperoxia, via modulating both intrinsic and extrinsic apoptosis pathways. PMID:27257854

  4. Osteoblast-like cell behavior on plasma deposited micro/nanopatterned coatings.

    PubMed

    Intranuovo, Francesca; Favia, Pietro; Sardella, Eloisa; Ingrosso, Chiara; Nardulli, Marina; d'Agostino, Riccardo; Gristina, Roberto

    2011-02-14

    The behavior of cells in terms of cell-substrate and cell-cell interaction is dramatically affected by topographical characteristics as shape, height, and distance, encountered in their physiological environment. The combination of chemistry and topography of a biomaterial surface influences in turns, important biological responses as inflammatory events at tissue-implant interface, angiogenesis, and differentiation of cells. By disentangling the effect of material chemistry from the topographical one, the possibility of controlling the cell behavior can be provided. In this paper, surfaces with different roughness and morphology were produced by radiofrequency (RF, 13.56 MHz) glow discharges, fed with hexafluoropropylene oxide (C(3)F(6)O), in a single process. Coatings with different micro/nanopatterns and the same uppermost chemical composition were produced by combining two plasma deposition processes, with C(3)F(6)O and tetrafluoroethylene (C(2)F(4)), respectively. The behavior of osteoblast-like cells toward these substrates clearly shows a strict dependence of cell adhesion and proliferation on surface roughness and morphology.

  5. 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

  6. MicroRNA-203 induces apoptosis by upregulating Puma expression in colon and lung cancer cells.

    PubMed

    Funamizu, Naotake; Lacy, Curtis R; Kamada, Minori; Yanaga, Katsuhiko; Manome, Yoshinobu

    2015-11-01

    The present study investigated the relationship between microRNA-203 (miR-203) and the p53 upregulated modulator of apoptosis (Puma) in colon (HCT116) and lung cancer (A549) cells. Colon and lung cancer cell lines were selected for this study since a relationship between p53/miR-203 and p53/Puma has been established in both cancers. In the present study, adriamycin and nutlin-3 were used to activate p53, which induced both miR-203 and Puma expression in HCT116 cells. In contrast, HCT 116 cells with downregulated p53 showed decreased miR-203 and Puma expression. Importantly, we found that overexpressed miR-203 in HCT116 cells resulted in significantly increased Puma expression (P<0.05). Based on these findings, we hypothesized that another limb of the p53/Puma axis depends on miR-203 expression. To further validate this relationship, we used lung cancer cells (A549) and found that activated p53 increased both miR-203 and Puma expression. In addition, we found that Puma expression remained elevated in cells with overexpressed miR-203 in the presence of p53 downregulation. Cumulatively, our data purport that p53 not only increased Puma expression directly, but that it may also do so through miR-203. Additionally, functional studies revealed that miR-203 overexpression induced apoptosis and inhibited cell invasiveness.

  7. MicroRNA-9 suppresses the sensitivity of CNE2 cells to ultraviolet radiation.

    PubMed

    Zheng, Chao-Pan; Han, Ling; Hou, Wei-Jian; Tang, Jun; Wen, Yi-Hui; Fu, Ran; Wang, Yue-Jian; Wen, Wei-Ping

    2015-08-01

    MicroRNA (miR)-9 has been demonstrated to regulate the radiosensitivity of tumor cells. In the present study, the mechanism by which miR-9 modulates the sensitivity of nasopharyngeal carcinoma (NPC) cells to ultraviolet (UV) radiation was investigated. The results demonstrated that exposure of NPC cells to UV light resulted in a significant increase in the expression of miR-9, and that CNE2 cells overexpressing miR-9 exhibited reduced levels of DNA damage and increased levels of total glutathione upon UV exposure. Accordingly, the inhibition of the expression of miR-9 promoted UV-induced DNA damage and apoptosis. Although miR-9 inhibited the expression of E-cadherin in the CNE2 cells and increased their resistance to UV radiation, the use of small interfering RNA to inhibit the expression of E-cadherin was not sufficient to decrease the radiosensitivity of the NPC cells. These data demonstrated that miR-9 did not modulate the sensitivity of the CNE2 cells to UV radiation through E-cadherin, but suggested that miR-9 regulated radiosensitivity through its effects on glutathione. These findings suggest that miR-9 may be a potential target for modulating the radiosensitivity of NPC cells.

  8. Controlling cell adhesion via replication of laser micro/nano-textured surfaces on polymers.

    PubMed

    Koufaki, Niki; Ranella, Anthi; Aifantis, Katerina E; Barberoglou, Marios; Psycharakis, Stylianos; Fotakis, Costas; Stratakis, Emmanuel

    2011-12-01

    The aim of this study is to investigate cell adhesion and viability on highly rough polymeric surfaces with gradient roughness ratios and wettabilities prepared by microreplication of laser micro/nano-textured Si surfaces. Negative replicas on polydimethylsiloxane as well as positive ones on a photocurable (organically modified ceramic) and a biodegradable (poly(lactide-co-glycolide)) polymer have been successfully reproduced. The final culture substrates comprised from forests of micron-sized conical spikes exhibiting a range of roughness ratios and wettabilities, was achieved by changing the laser fluence used to fabricate the original template surfaces. Cell culture experiments were performed with the fibroblast NIH/3T3 and PC12 neuronal cell lines in order to investigate how these surfaces are capable of modulating different types of cellular responses including, viability, adhesion and morphology. The results showed a preferential adhesion of both cell types on the microstructured surfaces compared to the unstructured ones. In particular, the fibroblast NIH/3T3 cells show optimal adhesion for small roughness ratios, independent of the surface wettability and polymer type, indicating a non-monotonic dependence of cell adhesion on surface energy. In contrast, the PC12 cells were observed to adhere well to the patterned surfaces independent of the roughness ratio and wettability. These experimental findings are correlated with micromechanical measurements performed on the unstructured and replicated surfaces and discussed on the basis of previous observations describing the relation of cell response to surface energy and rigidity.

  9. Regulation of Neuronal Cell Cycle and Apoptosis by MicroRNA 34a

    PubMed Central

    Modi, Prashant Kumar; Jaiswal, Surbhi

    2015-01-01

    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. Characterization of intrinsic a-Si:H films prepared by inductively coupled plasma chemical vapor deposition for solar cell applications.

    PubMed

    Jeong, Chaehwan; Boo, Seongjae; Jeon, Minsung; Kamisako, Koichi

    2007-11-01

    The hydrogenated amorphous silicon (a-Si:H) films, which can be used as the passivation or absorption layer of solar cells, were prepared by inductively coupled plasma chemical vapor deposition (ICP-CVD) and their characteristics were studied. Deposition process of a-Si:H films was performed by varying the parameters, gas ratio (H2/SiH4), radio frequency (RF) power and substrate temperature, while a working pressure was fixed at 70 m Torr. Their characteristics were studied by measuring thickness, optical bandgap (eV), photosensitivity, bond structure and surface roughness. When the RF power and substrate temperature were 300 watt and 200 degrees C, respectively, optical bandgap and photosensitivity, similar to the intrinsic a-Si:H film, were obtained. The Si-H stretching mode at 2000 cm(-1), which means a good quality of films, was found at all conditions. Although the RF power increased up to 400 watt, average of surface roughness got better, compared to a-Si:H films deposited by the conventional PECVD method. These results show the potential for developing the solar cells using ICP-CVD, which have the relatively less damage of plasma.

  11. MicroRNA-7 Promotes Glycolysis to Protect against 1-Methyl-4-phenylpyridinium-induced Cell Death.

    PubMed

    Chaudhuri, Amrita Datta; Kabaria, Savan; Choi, Doo Chul; Mouradian, M Maral; Junn, Eunsung

    2015-05-01

    Parkinson disease is associated with decreased activity of the mitochondrial electron transport chain. This defect can be recapitulated in vitro by challenging dopaminergic cells with 1-methyl-4-phenylpyridinium (MPP(+)), a neurotoxin that inhibits complex I of electron transport chain. Consequently, oxidative phosphorylation is blocked, and cells become dependent on glycolysis for ATP production. Therefore, increasing the rate of glycolysis might help cells to produce more ATP to meet their energy demands. In the present study, we show that microRNA-7, a non-coding RNA that protects dopaminergic neuronal cells against MPP(+)-induced cell death, promotes glycolysis in dopaminergic SH-SY5Y and differentiated human neural progenitor ReNcell VM cells, as evidenced by increased ATP production, glucose consumption, and lactic acid production. Through a series of experiments, we demonstrate that targeted repression of RelA by microRNA-7, as well as subsequent increase in the neuronal glucose transporter 3 (Glut3), underlies this glycolysis-promoting effect. Consistently, silencing Glut3 expression diminishes the protective effect of microRNA-7 against MPP(+). Further, microRNA-7 fails to prevent MPP(+)-induced cell death when SH-SY5Y cells are cultured in a low glucose medium, as well as when differentiated ReNcell VM cells or primary mouse neurons are treated with the hexokinase inhibitor, 2-deoxy-d-glucose, indicating that a functional glycolytic pathway is required for this protective effect. In conclusion, microRNA-7, by down-regulating RelA, augments Glut3 expression, promotes glycolysis, and subsequently prevents MPP(+)-induced cell death. This protective effect of microRNA-7 could be exploited to correct the defects in oxidative phosphorylation in Parkinson disease. PMID:25814668

  12. 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

  13. 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.

  14. Dielectrophoretic cell trapping and parallel one-to-one fusion based on field constriction created by a micro-orifice array

    PubMed Central

    Gel, Murat; Kimura, Yuji; Kurosawa, Osamu; Oana, Hidehiro; Kotera, Hidetoshi; Washizu, Masao

    2010-01-01

    Micro-orifice based cell fusion assures high-yield fusion without compromising the cell viability. This paper examines feasibility of a dielectrophoresis (DEP) assisted cell trapping method for parallel fusion with a micro-orifice array. The goal is to create viable fusants for studying postfusion cell behavior. We fabricated a microfluidic chip that contained a chamber and partition. The partition divided the chamber into two compartments and it had a number of embedded micro-orifices. The voltage applied to the electrodes located at each compartment generated an electric field distribution concentrating in micro-orifices. Cells introduced into each compartment moved toward the micro-orifice array by manipulation of hydrostatic pressure. DEP assisted trapping was used to keep the cells in micro-orifice and to establish cell to cell contact through orifice. By applying a pulse, cell fusion was initiated to form a neck between cells. The neck passing through the orifice resulted in immobilization of the fused cell pair at micro-orifice. After washing away the unfused cells, the chip was loaded to a microscope with stage top incubator for time lapse imaging of the selected fusants. The viable fusants were successfully generated by fusion of mouse fibroblast cells (L929). Time lapse observation of the fusants showed that fused cell pairs escaping from micro-orifice became one tetraploid cell. The generated tetraploid cells divided into three daughter cells. The fusants generated with a smaller micro-orifice (diameter∼2 μm) were kept immobilized at micro-orifice until cell division phase. After observation of two synchronized cell divisions, the fusant divided into four daughter cells. We conclude that the presented method of cell pairing and fusion is suitable for high-yield generation of viable fusants and furthermore, subsequent study of postfusion phenomena. PMID:20697592

  15. Vapor fragrancer

    NASA Astrophysics Data System (ADS)

    Sang, Q. Tran; Bryant, Timothy D.

    1987-05-01

    This invention relates to a vapor fragrancer for continuously, uniformly, and economically odorizing or deodorizing an environment. Homes, offices, automobiles, and space stations require either odorizing or deodorizing of the atmosphere to create pleasant conditions for work or leisure. A vapor fragrancer is provided to accomplish these goals. A supplier continuously supplies a predetermined amount of desired liquid fragrance from a container to a retaining material, which is positioned in the circulation path of the atmosphere. The supplier is either a low powered pump or a gravity dispenser. The atmosphere flowing in a circulation path passes over the retaining material containing the liquid fragrance and lifts a fragrant vapor from the retaining material. The atmosphere is thereby continuously and uniformly fragranced.

  16. 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

  17. 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).

  18. 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.

  19. 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

  20. 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.

  1. 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

  2. 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.

  3. MicroRNA regulation of myogenic satellite cell proliferation and differentiation.

    PubMed

    Harding, Rachel L; Velleman, Sandra G

    2016-01-01

    Myogenic satellite cells are stem cells responsible for muscle growth and regeneration. MicroRNAs (miRNAs) play significant roles in regulating numerous cellular processes. Two genes essential to satellite cell function are syndecan-4 and glypican-1. To determine if miRNAs influence myogenic satellite cell function, one miRNA predicted to bind syndecan-4 (miR-128) and two predicted to bind glypican-1 (miR-24 and miR-16) were inhibited in vitro by transfection of inhibitors targeting each miRNA. Inhibition of these miRNAs differentially affected the expression of syndecan-4, glypican-1, and myogenic regulatory factors myoD and myogenin. Inhibition of miR-16 reduced proliferation of satellite cells at 72 h. Inhibition of miR-128 and miR-24 did not affect proliferation. Inhibition of miRNAs reduced differentiation of satellite cells into myotubes at 48 and 72 h except for miR-16, which only affected differentiation at 72 h. Inhibition of all three miRNAs decreased myotube width at 24 h of differentiation and increased myotube width at 48 h of differentiation. Inhibiting these miRNAs also increased the number of nuclei per myotube at 72 h of differentiation. These data demonstrate individual miRNAs regulate genes essential for myogenic satellite cell proliferation and differentiation.

  4. 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.

  5. MicroRNA-203 inhibits malignant melanoma cell migration by targeting versican.

    PubMed

    Bu, Pingyuan; Yang, Ping

    2014-07-01

    MicroRNA (miR)-203 has been demonstrated to function as a suppressor in tumorigenesis. Recently, miR-203 was reported to play a role in malignant melanoma (MM); however, the detailed function of miR-203 in MM remains unclear. In the present study, the expression of miR-203 was shown to be significantly downregulated in MM tissues when compared with normal adjacent tissues. Based on a bioinformatic prediction, versican was further identified as a novel target of miR-203, and the expression of versican was markedly increased in MM tissues. Inhibition of miR-203 increased the protein expression of versican, while upregulation of miR-203 inhibited the protein expression of versican in MM A375 cells. In addition, the upregulation of versican significantly promoted A375 cell migration; however, upregulation of miR-203 suppressed A375 cell migration. The present study further investigated whether miR-203 was involved in versican-mediated A375 cell migration, and the results indicated that upregulation of miR-203 significantly inhibited A375 cell migration, which was impaired by overexpression of versican. These observations indicated that versican functions as a downstream effector in miR-203-mediated MM cell migration. Therefore, the results demonstrated that miR-203 exhibited an inhibitory effect on MM cell migration via directly targeting versican, thus, may become an effective inhibitor for MM metastasis.

  6. MicroRNA-155 confers encephalogenic potential to Th17 cells by promoting effector gene expression

    PubMed Central

    Hu, Ruozhen; Huffaker, Thomas B.; Kagele, Dominique A.; Runtsch, Marah C.; Bake, Erin; Chaudhuri, Aadel A.; Round, June L.; O’Connell, Ryan M.

    2013-01-01

    Th17 cells are central to the pathogenesis of autoimmune disease, and recently specific noncoding microRNAs (miRNAs) have been shown to regulate their development. However, it remains unclear if miRNAs 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 (EAE). Using adoptive transfer experiments, we found that highly purified, MOG antigen-specific Th17 cells lacking miR-155 were defective in their capacity to cause EAE. Gene expression profiling of purified miR-155−/− IL-17F+ Th17 cells identified a subset of effector genes that are dependent upon 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 hypo-responsive 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

  7. 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

  8. MicroRNA-370 directly targets FOXM1 to inhibit cell growth and metastasis in osteosarcoma cells.

    PubMed

    Duan, Ning; Hu, Xiaojing; Yang, Xiaowei; Cheng, Huiguang; Zhang, Wentao

    2015-01-01

    MicroRNAs (miRNAs) are endogenous, non-coding, small RNAs, which play a critical role in regulating varieties of the biological and pathologic processes. Several reports have indicated that miR-370 acts as a tumor suppressor in varieties of tumors. However, the roles of miR-370 in osteosarcoma have not been reported. In this study, our objective was to explore the biological functions and its molecular mechanism of miR-370 in osteosarcoma cell lines, finding a therapeutic target of osteosarcoma. Our data demonstrated that miR-370 was evidently reduced in osteosarcoma cell lines, whereas FOXM1 expression was markedly increased. Up-regulation of miR-370 suppressed proliferation, arrested cell cycle and induced apoptosis in osteosarcoma cells. Besides, invasion and EMT of osteosarcoma cells was also inhibited by introduction of miR-370. Next, we found that FOXM1 expression was significantly reduced by up-regulation of miR-370. Bioinformatics analysis predicted that the FOXM1 was a potential target gene of miR-370. Luciferase reporter assay further confirmed that miR-370 could directly target the 3' UTR of FOXM1. Overexpression of FOXM1 in osteosarcoma cells transfected with miR-370 mimic partially reversed the effects of miR-370. In conclusion, miR-370 inhibited cell growth and metastasis in osteosarcoma cells by down-regulation of FOXM1.

  9. 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

  10. microRNA-153 Targets mTORC2 Component Rictor to Inhibit Glioma Cells.

    PubMed

    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

  11. Maternal peripheral blood natural killer cells incorporate placenta-associated microRNAs during pregnancy.

    PubMed

    Ishida, Yoichi; Zhao, Dongwei; Ohkuchi, Akihide; Kuwata, Tomoyuki; Yoshitake, Hiroshi; Yuge, Kazuya; Takizawa, Takami; Matsubara, Shigeki; Suzuki, Mitsuaki; Saito, Shigeru; Takizawa, Toshihiro

    2015-06-01

    Although recent studies have demonstrated that microRNAs (miRNAs or miRs) regulate fundamental natural killer (NK) cellular processes, including cytotoxicity and cytokine production, little is known about the miRNA-gene regulatory relationships in maternal peripheral blood NK (pNK) cells during pregnancy. In the present study, to determine the roles of miRNAs within gene regulatory networks of maternal pNK cells, we performed comprehensive miRNA and gene expression profiling of maternal pNK cells using a combination of reverse transcription quantitative PCR (RT-qPCR)-based miRNA array and DNA microarray analyses and analyzed the differential expression levels between first- and third-trimester pNK cells. Furthermore, we constructed regulatory networks for miRNA-mediated gene expression in pNK cells during pregnancy by Ingenuity Pathway Analysis (IPA). PCR-based array analysis revealed that the placenta-derived miRNAs [chromosome 19 miRNA cluster (C19MC) miRNAs] were detected in pNK cells during pregnancy. Twenty-five miRNAs, including six C19MC miRNAs, were significantly upregulated in the third- compared to first-trimester pNK cells. The rapid clearance of C19MC miRNAs also occurred in the pNK cells following delivery. Nine miRNAs, including eight C19MC miRNAs, were significantly downregulated in the post-delivery pNK cells compared to those of the third-trimester. DNA microarray analysis identified 69 NK cell function-related genes that were differentially expressed between the first- and third-trimester pNK cells. On pathway and network analysis, the observed gene expression changes of pNK cells likely contribute to the increase in the cytotoxicity, as well as the cell cycle progression of third- compared to first-trimester pNK cells. Thirteen of the 69 NK cell function-related genes were significantly downregulated between the first- and third-trimester pNK cells. Nine of the 13 downregulated NK-function-associated genes were in silico target candidates of 12

  12. Sub-doppler spectroscopy of sodium vapor in an ultrathin cell

    NASA Astrophysics Data System (ADS)

    Khanbekyan, K. A.; Mariotti, E.; Khanbekyan, A. A.; Moi, L.; Khanbekyan, A. M.

    2016-05-01

    The results obtained in a cell with a distance between windows on the order of several hundreds of nanometers (the so-called "nanocell") are presented. The nanocell thickness L in the vertical direction changes from 100 to 900 nm. It is shown that the use of a nanocell with thickness L = λ/2, where λ is a laser wavelength resonant to the atomic transition D2 in sodium atoms, provides sub-Doppler resolution of transmission and fluorescence spectra.

  13. 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.

  14. 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

  15. 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.

  16. Control of cell proliferation in Arabidopsis thaliana by microRNA miR396.

    PubMed

    Rodriguez, Ramiro E; Mecchia, Martin A; Debernardi, Juan M; Schommer, Carla; Weigel, Detlef; Palatnik, Javier F

    2010-01-01

    Cell proliferation is an important determinant of plant form, but little is known about how developmental programs control cell division. Here, we describe the role of microRNA miR396 in the coordination of cell proliferation in Arabidopsis leaves. In leaf primordia, miR396 is expressed at low levels that steadily increase during organ development. We found that miR396 antagonizes the expression pattern of its targets, the GROWTH-REGULATING FACTOR (GRF) transcription factors. miR396 accumulates preferentially in the distal part of young developing leaves, restricting the expression of GRF2 to the proximal part of the organ. This, in turn, coincides with the activity of the cell proliferation marker CYCLINB1;1. We show that miR396 attenuates cell proliferation in developing leaves, through the repression of GRF activity and a decrease in the expression of cell cycle genes. We observed that the balance between miR396 and the GRFs controls the final number of cells in leaves. Furthermore, overexpression of miR396 in a mutant lacking GRF-INTERACTING FACTOR 1 severely compromises the shoot meristem. We found that miR396 is expressed at low levels throughout the meristem, overlapping with the expression of its target, GRF2. In addition, we show that miR396 can regulate cell proliferation and the size of the meristem. Arabidopsis plants with an increased activity of the transcription factor TCP4, which reduces cell proliferation in leaves, have higher miR396 and lower GRF levels. These results implicate miR396 as a significant module in the regulation of cell proliferation in plants.

  17. 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

  18. Profile of Exosomal and Intracellular microRNA in Gamma-Herpesvirus-Infected Lymphoma Cell Lines

    PubMed Central

    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

  19. 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

  20. Regulation of Pancreatic Beta Cell Stimulus-Secretion Coupling by microRNAs

    PubMed Central

    Esguerra, Jonathan L. S.; Mollet, Inês G.; Salunkhe, Vishal A.; Wendt, Anna; Eliasson, Lena

    2014-01-01

    Increased blood glucose after a meal is countered by the subsequent increased release of the hypoglycemic hormone insulin from the pancreatic beta cells. The cascade of molecular events encompassing the initial sensing and transport of glucose into the beta cell, culminating with the exocytosis of the insulin large dense core granules (LDCVs) is termed “stimulus-secretion coupling.” Impairment in any of the relevant processes leads to insufficient insulin release, which contributes to the development of type 2 diabetes (T2D). The fate of the beta cell, when exposed to environmental triggers of the disease, is determined by the possibility to adapt to the new situation by regulation of gene expression. As established factors of post-transcriptional regulation, microRNAs (miRNAs) are well-recognized mediators of beta cell plasticity and adaptation. Here, we put focus on the importance of comprehending the transcriptional regulation of miRNAs, and how miRNAs are implicated in stimulus-secretion coupling, specifically those influencing the late stages of insulin secretion. We suggest that efficient beta cell adaptation requires an optimal balance between transcriptional regulation of miRNAs themselves, and miRNA-dependent gene regulation. The increased knowledge of the beta cell transcriptional network inclusive of non-coding RNAs such as miRNAs is essential in identifying novel targets for the treatment of T2D. PMID:25383562

  1. 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.

  2. Nanoparticle-Delivered Antisense MicroRNA-21 Enhances the Effects of Temozolomide on Glioblastoma Cells.

    PubMed

    Ananta, Jeyarama S; Paulmurugan, Ramasamy; Massoud, Tarik F

    2015-12-01

    Glioblastoma (GBM) generally exhibits high IC50 values for its standard drug treatment, temozolomide (TMZ). MicroRNA-21 (miR-21) is an oncomiR overexpressed in GBM, thus controlling important aspects of glioma biology. We hypothesized that PLGA nanoparticles carrying antisense miR-21 to glioblastoma cells might beneficially knock down endogenous miR-21 prior to TMZ treatment. PLGA nanoparticles encapsulating antisense miR-21 were effective in intracellular delivery and sustained silencing (p < 0.01) of miR-21 function in U87 MG, LN229, and T98G cells. Prior antisense miR-21 delivery significantly reduced the number of viable cells (p < 0.001), and increased (1.6-fold) cell cycle arrest at G2/M phase upon TMZ treatment in U87 MG cells. There was overexpression of the miR-21 target genes PTEN (by 67%) and caspase-3 (by 15%) upon cotreatment. This promising PLGA nanoparticle-based platform for antisense miR-21 delivery to GBM is an effective cotherapeutic strategy in cell culture, warranting the need for further studies prior to future clinical translation. PMID:26559642

  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. 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

  5. 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

  6. 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

  7. 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.

  8. 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

  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

    2016-08-31

    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.

  10. 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

  11. Flow bioreactor design for quantitative measurements over endothelial cells using micro-particle image velocimetry.

    PubMed

    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.

  12. 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'.

  13. 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

  14. 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

  15. 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

  16. A low phase noise microwave frequency synthesis for a high-performance cesium vapor cell atomic clock

    SciTech Connect

    François, B.; Boudot, R.; Calosso, C. E.; Danet, J. M.

    2014-09-15

    We report the development, absolute phase noise, and residual phase noise characterization of a 9.192 GHz microwave frequency synthesis chain devoted to be used as a local oscillator in a high-performance cesium vapor cell atomic clock based on coherent population trapping (CPT). It is based on frequency multiplication of an ultra-low phase noise 100 MHz oven-controlled quartz crystal oscillator using a nonlinear transmission line-based chain. Absolute phase noise performances of the 9.192 GHz output signal are measured to be −42, −100, −117 dB rad{sup 2}/Hz and −129 dB rad{sup 2}/Hz at 1 Hz, 100 Hz, 1 kHz, and 10 kHz offset frequencies, respectively. Compared to current results obtained in a state-of-the-art CPT-based frequency standard developed at LNE-SYRTE, this represents an improvement of 8 dB and 10 dB at f = 166 Hz and f = 10 kHz, respectively. With such performances, the expected Dick effect contribution to the atomic clock short term frequency stability is reported at a level of 6.2 × 10{sup −14} at 1 s integration time, that is a factor 3 higher than the atomic clock shot noise limit. Main limitations are pointed out.

  17. A low phase noise microwave frequency synthesis for a high-performance cesium vapor cell atomic clock

    NASA Astrophysics Data System (ADS)

    François, B.; Calosso, C. E.; Danet, J. M.; Boudot, R.

    2014-09-01

    We report the development, absolute phase noise, and residual phase noise characterization of a 9.192 GHz microwave frequency synthesis chain devoted to be used as a local oscillator in a high-performance cesium vapor cell atomic clock based on coherent population trapping (CPT). It is based on frequency multiplication of an ultra-low phase noise 100 MHz oven-controlled quartz crystal oscillator using a nonlinear transmission line-based chain. Absolute phase noise performances of the 9.192 GHz output signal are measured to be -42, -100, -117 dB rad2/Hz and -129 dB rad2/Hz at 1 Hz, 100 Hz, 1 kHz, and 10 kHz offset frequencies, respectively. Compared to current results obtained in a state-of-the-art CPT-based frequency standard developed at LNE-SYRTE, this represents an improvement of 8 dB and 10 dB at f = 166 Hz and f = 10 kHz, respectively. With such performances, the expected Dick effect contribution to the atomic clock short term frequency stability is reported at a level of 6.2 × 10-14 at 1 s integration time, that is a factor 3 higher than the atomic clock shot noise limit. Main limitations are pointed out.

  18. Spatial transport of atomic coherence in electromagnetically induced absorption with a paraffin-coated Rb vapor cell.

    PubMed

    Lee, Yoon-Seok; Moon, Han Seb

    2014-06-30

    We report the spatial transport of spontaneously transferred atomic coherence (STAC) in electromagnetically induced absorption (EIA), which resulted from moving atoms with the STAC of the 5S(1/2) (F = 2)-5P(3/2) (F' = 3) transition of (87)Rb in a paraffin-coated vapor cell. In our experiment, two channels were spatially separate; the writing channel (WC) generated STAC in the EIA configuration, and the reading channel (RC) retrieved the optical field from the spatially transported STAC. Transported between the spatially separated positions, the fast light pulse of EIA in the WC and the delayed light pulse in the RC were observed. When the laser direction of the RC was counter-propagated in the direction of the WC, we observed direction reversal of the transported light pulse in the EIA medium. Furthermore, the delay time, the magnitude, and the width of the spatially transported light pulse were investigated with respect to the distance between the two channels. PMID:24977849

  19. A low phase noise microwave frequency synthesis for a high-performance cesium vapor cell atomic clock.

    PubMed

    François, B; Calosso, C E; Danet, J M; Boudot, R

    2014-09-01

    We report the development, absolute phase noise, and residual phase noise characterization of a 9.192 GHz microwave frequency synthesis chain devoted to be used as a local oscillator in a high-performance cesium vapor cell atomic clock based on coherent population trapping (CPT). It is based on frequency multiplication of an ultra-low phase noise 100 MHz oven-controlled quartz crystal oscillator using a nonlinear transmission line-based chain. Absolute phase noise performances of the 9.192 GHz output signal are measured to be -42, -100, -117 dB rad(2)/Hz and -129 dB rad(2)/Hz at 1 Hz, 100 Hz, 1 kHz, and 10 kHz offset frequencies, respectively. Compared to current results obtained in a state-of-the-art CPT-based frequency standard developed at LNE-SYRTE, this represents an improvement of 8 dB and 10 dB at f = 166 Hz and f = 10 kHz, respectively. With such performances, the expected Dick effect contribution to the atomic clock short term frequency stability is reported at a level of 6.2 × 10(-14) at 1 s integration time, that is a factor 3 higher than the atomic clock shot noise limit. Main limitations are pointed out. PMID:25273756

  20. Spatial transport of atomic coherence in electromagnetically induced absorption with a paraffin-coated Rb vapor cell.

    PubMed

    Lee, Yoon-Seok; Moon, Han Seb

    2014-06-30

    We report the spatial transport of spontaneously transferred atomic coherence (STAC) in electromagnetically induced absorption (EIA), which resulted from moving atoms with the STAC of the 5S(1/2) (F = 2)-5P(3/2) (F' = 3) transition of (87)Rb in a paraffin-coated vapor cell. In our experiment, two channels were spatially separate; the writing channel (WC) generated STAC in the EIA configuration, and the reading channel (RC) retrieved the optical field from the spatially transported STAC. Transported between the spatially separated positions, the fast light pulse of EIA in the WC and the delayed light pulse in the RC were observed. When the laser direction of the RC was counter-propagated in the direction of the WC, we observed direction reversal of the transported light pulse in the EIA medium. Furthermore, the delay time, the magnitude, and the width of the spatially transported light pulse were investigated with respect to the distance between the two channels.

  1. 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.

  2. 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

  3. Mechanisms of the micro-crack generation in an ultra-thin AlN/GaN superlattice structure grown on Si(110) substrates by metalorganic chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Shen, X. Q.; Takahashi, T.; Ide, T.; Shimizu, M.

    2015-09-01

    We investigate the generation mechanisms of micro-cracks (MCs) in an ultra-thin AlN/GaN superlattice (SL) structure grown on Si(110) substrates by metalorganic chemical vapor deposition. The SL is intended to be used as an interlayer (IL) for relaxing tensile stress and obtaining high-quality crack-free GaN grown on Si substrates. It is found that the MCs can be generated by two different mechanisms, where large mismatches of the lattice constant (LC) and the coefficient of thermal expansion (CTE) play key roles in the issue. Different MC configurations (low-density and high-density MCs) are observed, which are considered to be formed during the different growth stages (SL growth and cooling down processes) due to the LC and the CTE effects. In-situ and ex-situ experimental results support the mechanism interpretations of the MCs generation. The mechanism understanding makes it possible to optimize the SL IL structure for growing high-quality crack-free GaN films on Si substrates for optical and electronic device applications.

  4. Mechanisms of the micro-crack generation in an ultra-thin AlN/GaN superlattice structure grown on Si(110) substrates by metalorganic chemical vapor deposition

    SciTech Connect

    Shen, X. Q. Takahashi, T.; Ide, T.; Shimizu, M.

    2015-09-28

    We investigate the generation mechanisms of micro-cracks (MCs) in an ultra-thin AlN/GaN superlattice (SL) structure grown on Si(110) substrates by metalorganic chemical vapor deposition. The SL is intended to be used as an interlayer (IL) for relaxing tensile stress and obtaining high-quality crack-free GaN grown on Si substrates. It is found that the MCs can be generated by two different mechanisms, where large mismatches of the lattice constant (LC) and the coefficient of thermal expansion (CTE) play key roles in the issue. Different MC configurations (low-density and high-density MCs) are observed, which are considered to be formed during the different growth stages (SL growth and cooling down processes) due to the LC and the CTE effects. In-situ and ex-situ experimental results support the mechanism interpretations of the MCs generation. The mechanism understanding makes it possible to optimize the SL IL structure for growing high-quality crack-free GaN films on Si substrates for optical and electronic device applications.

  5. A depletable micro-layer model for nucleate pool boiling

    NASA Astrophysics Data System (ADS)

    Sato, Yohei; Niceno, Bojan

    2015-11-01

    A depletable micro-layer model has been developed for the simulation of nucleate pool boiling within the framework of Computational Fluid Dynamics (CFD) modeling using an interface-tracking method. A micro-layer model is required for the CFD simulation to take into account vaporization from the thin liquid film - called the micro-layer - existing beneath a growing vapor bubble on a hot surface. In our model, the thickness of the micro-layer is a variable defined at each discretized fluid cell adjacent to the heat-transfer surface; the layer decreases due to vaporization, and can finally disappear. Compared to existing micro-region models, most of them based on the concept of contact-line evaporation, as originally proposed by Stephan and Busse, and by Lay and Dhir, our model incorporates simplified modeling ideas, but can nonetheless predict the temperature field beneath the growing bubble accurately. The model proposed in this paper has been validated against measurements of pool boiling in water at atmospheric pressure. Specifically, the bubble principal dimensions and the temperature distribution over the heat-transfer surface are in good agreement with experimental data.

  6. 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.

  7. Melatonin promotes distal dendritic ramifications in layer II/III cortical pyramidal cells of rats exposed to toluene vapors.

    PubMed

    Pascual, Rodrigo; Bustamante, Carlos

    2010-10-01

    We have previously shown that toluene inhalation produces significant impairments in the basilar dendritic outgrowth of pyramidal cortical cells. This neurotoxic effect was markedly inhibited by melatonin administration at a dose of 5mg kg(-1). The present study was designed to determine whether toluene and melatonin equally affect all basilar dendritic segments or if a differential response exists between the segments. Twenty-eight male mice were weaned at postnatal day 21 (P21) and randomly assigned to either the control (C; n=10,) or toluene (T; n=18) group. Between P22-P32, male rats were placed into a glass chamber and exposed to either toluene vapors (5-000-6000 ppm) or clean air for 10 min a day. When toluene exposure ended (P32), animals were further assigned to the following experimental groups: (a) control/saline (C/S; n=10), (b) toluene/saline (T/S; n=10), or (c) toluene/melatonin 5mg kg(-1) (T/M; n=8). Melatonin or vehicle solutions were administered daily between P32 and P38. Forty-eight hours after the final toluene exposure, the animals were sacrificed, and the pyramidal cortical cells were stained using the Golgi-Cox-Sholl procedure. The number of basilar dendritic branches/order was counted using the centrifugal ordering method. The results indicate that (i) toluene inhalation significantly impairs both proximal and distal basilar dendritic ramifications (in the parietal and frontal/occipital cortices, respectively) and (ii) melatonin both protects neurons from toluene neurotoxicity in all cortical areas studied and increases the complexity of the dendritic tree above control values.

  8. 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.

  9. MicroRNA delivery with osmotic polysorbitol-based transporter suppresses breast cancer cell proliferation.

    PubMed

    Muthiah, Muthunarayanan; Islam, Mohammad Ariful; Lee, Hwa-Jeong; Moon, Myoeng-Ju; Cho, Chong-Su; Park, In-Kyu

    2015-01-01

    MicroRNAs (miRNA) are short oligonucleotides of endogenous origin involved in post-transcriptional regulation and are altered in disease, making them potential therapeutic targets. miRNA replacement is necessary in cells with downregulated miRNAs levels in response to disease. miRNA 145 is a novel tumor suppressor gene involved in cell suppression, invasion and migration of cancer cells; it is downregulated in most cancers. Delivery of therapeutic miRNA using nanoparticles enhances the chances of successful delivery and expression of genes at the target site. We evaluated polysorbitol-mediated transporter (PSMT) in the cellular delivery of miRNA 145. The polysorbitol backbone possesses osmotic properties and leads to enhanced cellular uptake. PSMT delivers genes into cells by a caveolae-mediated endocytic pathway. Caveolae expression is usually altered in transformed cancer cells. Physicochemical characterization, and the transfection efficiency and transgene expression capability of PSMT/reporter plasmid DNA nanoparticles, were determined. GFP-tagged miRNA 145 delivery with PSMT was confirmed by confocal microscopy and Western blotting. The functional effects of miRNA 145 delivered with PSMT were analyzed by confocal microscopy, as well as in apoptosis, proliferation and wound healing assays. Finally, the expression of an miRNA 145 target protein, c-myc, was determined by Western blotting after intracellular delivery of PSMT/miRNA 145 nanoparticle (NP).

  10. 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

  11. MicroRNAs in regulation of pluripotency and somatic cell reprogramming

    PubMed Central

    Wang, Tian; Shi, San-bao; Sha, Hong-ying

    2013-01-01

    MicroRNAs (miRNAs), a group of small non-coding RNAs, have emerged as significant modulators in the establishment and generation of pluripotency, a developmental process that consists of complex cell-fate arrangements. The finding of embryonic stem cell (ESC) cycle-specific miRNAs reveals an important regulation scheme of pluripotency. Subsequent studies showed the ESC-enriched or ESC-depleted miRNAs can regulate induced pluripotent stem cells(iPSC). Moreover, miRNA profiling of iPSC and ESC may distinguish them from one another and facilitate the complex of regulatory network. The accumulative effects of miRNA action enable using miRNA alone to generate iPSCs. Despite the robustness of iPSC studies, further investigations are needed since miRNA may have more impact on induced pluripotency, and the roles of miRNAs in somatic cell nuclear transfer (SCNT), another approach toward cellular reprogramming, remains unclear. This point-of-view article will discuss miRNAs and their impact on the normal and induced pluripotency, as well as bring new insights on somatic cell reprogramming. PMID:23921205

  12. 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.

  13. Matrine alters microRNA expression profiles in SGC-7901 human gastric cancer cells.

    PubMed

    Li, Hailong; Xie, Shoupin; Liu, Xiaojun; Wu, Hongyan; Lin, Xingyao; Gu, Jing; Wang, Huping; Duan, Yongqiang

    2014-11-01

    Matrine, a major alkaloid extracted from Sophora flavescens, has been reported to possess antitumor properties in several types of cancers, including gastric cancer. However, its mechanisms of action on gastric cancer remain poorly understood. Dysregulation of microRNAs, a class of small, non-coding, regulatory RNA molecules involved in gene expression, is strongly correlated with cancer. The aim of the present study was to demonstrate that matrine treatment altered miRNA expression in SGC7901 cells. Using miRCURY™ microarray analysis, we identified 128 miRNAs substantially exhibiting >2-fold expression changes in matrine-treated cells relative to their expression levels in untreated cells. RT-qPCR was used to show that the levels of 8 miRNAs whose target genes were clustered in the cell cycle pathway increased, while levels of 14 miRNAs whose target genes were clustered in the MAPK signaling pathway decreased. These results were consistent with those from the miRNA microarray experiment. Bioinformatical analysis revealed that the majority of 57 identified enrichment pathways were highly involved in tumorigenesis. In conclusion, the results demonstrated that matrine induces considerable changes in the miRNA expression profiles of SGC7901 cells, suggesting miRNA microarray combined with RT-qPCR validation and bioinformatical analysis provide a novel and promising approach to identify anticancer targets and the mechanisms of matrine involved.

  14. Enoxacin inhibits growth of prostate cancer cells and effectively restores microRNA processing.

    PubMed

    Sousa, Elsa; Graça, Inês; Baptista, Tiago; Vieira, Filipa Q; Palmeira, Carlos; Henrique, Rui; Jerónimo, Carmen

    2013-05-01

    Prostate cancer (PCa) is one of the most incident malignancies worldwide. Although efficient therapy is available for early-stage PCa, treatment of advanced disease is mainly ineffective and remains a clinical challenge. microRNA (miRNA) dysregulation is associated with PCa development and progression. In fact, several studies have reported a widespread downregulation of miRNAs in PCa, which highlights the importance of studying compounds capable of restoring the global miRNA expression. The main aim of this study was to define the usefulness of enoxacin as an anti-tumoral agent in PCa, due to its ability to induce miRNA biogenesis in a TRBP-mediated manner. Using a panel of five PCa cell lines, we observed that all of them were wild type for the TARBP2 gene and expressed TRBP protein. Furthermore, primary prostate carcinomas displayed normal levels of TRBP protein. Remarkably, enoxacin was able to decrease cell viability, induce apoptosis, cause cell cycle arrest, and inhibit the invasiveness of cell lines. Enoxacin was also effective in restoring the global expression of miRNAs. This study is the first to show that PCa cells are highly responsive to the anti-tumoral effects of enoxacin. Therefore, enoxacin constitutes a promising therapeutic agent for PCa.

  15. 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.

  16. Epistasis between microRNAs 155 and 146a during T cell-mediated antitumor immunity

    PubMed Central

    Huffaker, Thomas B.; Hu, Ruozhen; Runtsch, Marah C.; Bake, Erin; Chen, Xinjian; Zhao, Jimmy; Round, June L.; Baltimore, David; O’Connell, Ryan M.

    2012-01-01

    SUMMARY An increased understanding of antitumor immunity is necessary to improve cell-based immunotherapies against human cancers. Here, we investigated the roles of two immune system-expressed microRNAs (miRNAs), miR-155 and miR-146a, in the regulation of antitumor immune responses. Our results indicate that miR-155 promotes and miR-146a inhibits IFNγ responses by T cells and reduced solid tumor growth in vivo. Using a novel double knockout (DKO) mouse strain deficient in both miR-155 and miR-146a, we have also identified an epistatic relationship between these two miRNAs. DKO mice had defective T cell responses and tumor growth phenotypes similar to miR-155−/− mice. Further analysis of the T cell compartment revealed that miR-155 modulates IFNγ expression through a mechanism involving repression of Ship1. Our work reveals critical roles for miRNAs in the reciprocal regulation of CD4+ and CD8+ T cell-mediated antitumor immunity, and demonstrates the dominant nature of miR-155 during its promotion of immune responses. PMID:23200854

  17. Imaging live cell in micro-liquid enclosure by X-ray laser diffraction

    NASA Astrophysics Data System (ADS)

    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.

  18. 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

  19. 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

  20. Syndecan-1 responsive microRNA-126 and 149 regulate cell proliferation in prostate cancer

    SciTech Connect

    Fujii, Tomomi; Shimada, Keiji; Tatsumi, Yoshihiro; Fujimoto, Kiyohide; Konishi, Noboru

    2015-01-02

    Highlights: • Syndecan-1 is highly expressed in androgen independent prostate cancer cells, PC3. • Syndecan-1 regulates the expression of miR-126 and -149 in prostate cancer cells. • MiR-126 and 149 control cell growth via p21 induction and senescence mechanism. • MiR-126 and 149 promote cell proliferation by suppressing SOX2, NANOG, and Oct4. - Abstract: MicroRNAs (miRNAs) are short (19–24 nt), low molecular weight RNAs that play important roles in the regulation of target genes associated with cell proliferation, differentiation, and development, by binding to the 3′-untranslated region of the target mRNAs. In this study, we examined the expression of miRNA-126 (miR-126) and miR-149 in prostate cancer, and investigated the molecular mechanisms by which they affect syndecan-1 in prostate cancer. Functional analysis of miR-126 and miR-149 was conducted in the prostate cancer cell lines, PC3, Du145, and LNCaP. The expression levels of SOX2, NANOG, Oct4, miR-126 and miR-149 were evaluated by quantitative RT-PCR. After silencing syndecan-1, miR-126, and/or miR-149 in the PC3 cells, cell proliferation, senescence, and p21 induction were assessed using the MTS assay, senescence-associated β-galactosidase (SA-β-Gal) assay, and immunocytochemistry, respectively. Compared to the Du145 and LNCaP cells, PC3 cells exhibited higher expression of syndecan-1. When syndecan-1 was silenced, the PC3 cells showed reduced expression of miR-126 and miR-149 most effectively. Suppression of miR-126 and/or miR-149 significantly inhibited cell growth via p21 induction and subsequently, induced senescence. The mRNA expression levels of SOX2, NANOG, and Oct4 were significantly increased in response to the silencing of miR-126 and/or miR-149. Our results suggest that miR-126 and miR-149 are associated with the expression of syndecan-1 in prostate cancer cells. These miRNAs promote cell proliferation by suppressing SOX2, NANOG, and Oct4. The regulation of these factors by mi

  1. Identification of crucial microRNAs and genes in hypoxia-induced human lung adenocarcinoma cells

    PubMed Central

    Geng, Ying; Deng, Lili; Su, Dongju; Xiao, Jinling; Ge, Dongjie; Bao, Yongxia; Jing, Hui

    2016-01-01

    Background Variations of microRNA (miRNA) expression profile in hypoxic lung cancer cells have not been studied so far. Therefore, using miRNA microarray technology, this study aimed to study the miRNA expression profile and investigate the potential crucial miRNAs and their target genes in hypoxia-induced human lung adenocarcinoma cells. Materials and methods Based on miRNA microarray, miRNA expression profiling of hypoxia-induced lung adenocarcinoma A549 cells was obtained. After identification of differentially expressed miRNAs (DE-miRNAs) in hypoxic cells, target genes of DE-miRNAs were predicted, and functional enrichment analysis of targets was conducted. Furthermore, the expression levels of DE-miRNAs and their target genes were validated by real-time quantitative polymerase chain reaction. In addition, using miRNA mimics, the effect of overexpressed DE-miRNAs on A549 cell behaviors (cell proliferation, cell cycle, and apoptosis) was evaluated. Results In total, 14 DE-miRNAs (nine upregulated miRNAs and five downregulated miRNAs) were identified in hypoxic cells, compared with normoxic cells. Target genes of both upregulated and downregulated miRNAs were enriched in the functions such as chromatin modification, and pathways such as Wnt signaling pathway and transforming growth factor (TGF)-β signaling pathway. The expression levels of several miRNAs and their target genes were confirmed, including hsa-miR-301b/FOXF2, hsa-miR-148b-3p/WNT10B, hsa-miR-769-5p/(SMAD2, ARID1A), and hsa-miR-622. Among them, hsa-miR-301b was verified to regulate FOXF2, and hsa-miR-769-5p was verified to modulate ARID1A. In addition, the overexpression of hsa-miR-301b and hsa-miR-769-5p significantly affected the cell cycle of A549 cells, but not cell proliferation and apoptosis. Conclusion miRNA expression profile was changed in hypoxia-induced lung cancer cells. Those validated miRNAs and genes may play crucial roles in the response of lung cancer cells to hypoxia. PMID:27524914

  2. Vapor and healing treatment for CH3NH3PbI3-xClx films toward large-area perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Gouda, Laxman; Gottesman, Ronen; Tirosh, Shay; Haltzi, Eynav; Hu, Jiangang; Ginsburg, Adam; Keller, David A.; Bouhadana, Yaniv; Zaban, Arie

    2016-03-01

    Hybrid methyl-ammonium lead trihalide perovskites are promising low-cost materials for use in solar cells and other optoelectronic applications. With a certified photovoltaic conversion efficiency record of 20.1%, scale-up for commercial purposes is already underway. However, preparation of large-area perovskite films remains a challenge, and films of perovskites on large electrodes suffer from non-uniform performance. Thus, production and characterization of the lateral uniformity of large-area films is a crucial step towards scale-up of devices. In this paper, we present a reproducible method for improving the lateral uniformity and performance of large-area perovskite solar cells (32 cm2). The method is based on methyl-ammonium iodide (MAI) vapor treatment as a new step in the sequential deposition of perovskite films. Following the MAI vapor treatment, we used high throughput techniques to map the photovoltaic performance throughout the large-area device. The lateral uniformity and performance of all photovoltaic parameters (Voc, Jsc, Fill Factor, Photo-conversion efficiency) increased, with an overall improved photo-conversion efficiency of ~100% following a vapor treatment at 140 °C. Based on XRD and photoluminescence measurements, We propose that the MAI treatment promotes a ``healing effect'' to the perovskite film which increases the lateral uniformity across the large-area solar cell. Thus, the straightforward MAI vapor treatment is highly beneficial for large scale commercialization of perovskite solar cells, regardless of the specific deposition method.Hybrid methyl-ammonium lead trihalide perovskites are promising low-cost materials for use in solar cells and other optoelectronic applications. With a certified photovoltaic conversion efficiency record of 20.1%, scale-up for commercial purposes is already underway. However, preparation of large-area perovskite films remains a challenge, and films of perovskites on large electrodes suffer from non

  3. MicroRNA125b-mediated Hedgehog signaling influences liver regeneration by chorionic plate-derived mesenchymal stem cells.

    PubMed

    Hyun, Jeongeun; Wang, Sihyung; Kim, Jieun; Kim, Gi Jin; Jung, Youngmi

    2015-09-15

    Although chorionic plate-derived mesenchymal stem cells (CP-MSCs) were shown to promote liver regeneration, the mechanisms underlying the effect remain unclear. Hedgehog (Hh) signaling orchestrates tissue reconstruction in damaged liver. MSCs release microRNAs mediating various cellular responses. Hence, we hypothesized that microRNAs from CP-MSCs regulated Hh signaling, which influenced liver regeneration. Livers were obtained from carbon tetrachloride (CCl4)-treated rats transplanted with human CP-MSCs (Tx) or saline (non-Tx). Sonic Hh, one of Hh ligands, increased in CCl4-treated liver, whereas it decreased in CP-MSC-treated liver with CCl4. The expression of Hh-target genes was significantly downregulated in the Tx. Reduced expansion of progenitors and regressed fibrosis were observed in the liver of the Tx rats. CP-MSCs suppressed the expression of Hh and profibrotic genes in co-cultured LX2 (human hepatic stellate cell) with CP-MSCs. MicroRNA-125b targeting smo was retained in exosomes of CP-MSCs. CP-MSCs with microRNA-125b inhibitor failed to attenuate the expression of Hh signaling and profibrotic genes in the activated HSCs. Therefore, these results demonstrated that microRNA-125b from CP-MSCs suppressed the activation of Hh signaling, which promoted the reduced fibrosis, suggesting that microRNA-mediated regulation of Hh signaling contributed to liver regeneration by CP-MSCs.

  4. Effects of cell-to-cell fuel mal-distribution on fuel cell performance and a means to reduce mal-distribution using MEMS micro-valves

    SciTech Connect

    Hensel, J.P.; Gemmen, R.S.; Thornton, J.D.; Vipperman, J.S.; Clark, W.W.; Bucci, B.A.

    2007-01-10

    Achieving uniform flow among the cells of a fuel cell stack plays a significant role in being able to operate at maximum capability and efficiency. This paper presents experimental data showing the importance of cell-to-cell fuel flow balancing on fuel cell performance, and a fuel cell energy management (FCEM) technique that has demonstrated the ability to improve stack performance. In a specially instrumented four-cell polymer electrolyte fuel cell that allows external control of the air, fuel, and water-cooling flows to each cell, fuel to a single cell was reduced. V–I curves collected under these unbalanced conditions are compared to curves collected when the fuel flow to each cell was balanced. Reducing the fuel flow to a single cell by 11% decreased the V–I curve cutoff load by 10%—demonstrating the degree of negative effect that unbalanced fuel flows can have on stack performance. Typical fuel cell stacks have no dynamic means to keep flows in the stack balanced between the cells, but through the use of custom-built, piezoelectric micro-valves, a simple flow control strategy, and this custom four-cell laboratory stack, the positive effects of FCEM flow balancing at three different fuel flow rates was demonstrated.

  5. Differential microRNA expression signatures and cell type-specific association with Taxol resistance in ovarian cancer cells.

    PubMed

    Kim, Yong-Wan; Kim, Eun Young; Jeon, Doin; Liu, Juinn-Lin; Kim, Helena Suhyun; Choi, Jin Woo; Ahn, Woong Shick

    2014-01-01

    Paclitaxel (Taxol) resistance remains a major obstacle for the successful treatment of ovarian cancer. MicroRNAs (miRNAs) have oncogenic and tumor suppressor activity and are associated with poor prognosis phenotypes. miRNA screenings for this drug resistance are needed to estimate the prognosis of the disease and find better drug targets. miRNAs that were differentially expressed in Taxol-resistant ovarian cancer cells, compared with Taxol-sensitive cells, were screened by Illumina Human MicroRNA Expression BeadChips. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used to identify target genes of selected miRNAs. Kaplan-Meier survival analysis was applied to identify dysregulated miRNAs in ovarian cancer patients using data from The Cancer Genome Atlas. A total of 82 miRNAs were identified in ovarian carcinoma cells compared to normal ovarian cells. miR-141, miR-106a, miR-200c, miR-96, and miR-378 were overexpressed, and miR-411, miR-432, miR-494, miR-409-3p, and miR-655 were underexpressed in ovarian cancer cells. Seventeen miRNAs were overexpressed in Taxol-resistant cells, including miR-663, miR-622, and HS_188. Underexpressed miRNAs in Taxol-sensitive cells included miR-497, miR-187, miR-195, and miR-107. We further showed miR-663 and miR-622 as significant prognosis markers of the chemo-resistant patient group. In particular, the downregulation of the two miRNAs was associated with better survival, perhaps increasing the sensitivity of cancer cells to Taxol. In the chemo-sensitive patient group, only miR-647 could be a prognosis marker. These miRNAs inhibit several interacting genes of p53 networks, especially in TUOS-3 and TUOS-4, and showed cell line-specific inhibition effects. Taken together, the data indicate that the three miRNAs are closely associated with Taxol resistance and potentially better prognosis factors. Our results suggest that these miRNAs were successfully and reliably identified and would be used in the

  6. Differential microRNA expression signatures and cell type-specific association with Taxol resistance in ovarian cancer cells

    PubMed Central

    Kim, Yong-Wan; Kim, Eun Young; Jeon, Doin; Liu, Juinn-Lin; Kim, Helena Suhyun; Choi, Jin Woo; Ahn, Woong Shick

    2014-01-01

    Paclitaxel (Taxol) resistance remains a major obstacle for the successful treatment of ovarian cancer. MicroRNAs (miRNAs) have oncogenic and tumor suppressor activity and are associated with poor prognosis phenotypes. miRNA screenings for this drug resistance are needed to estimate the prognosis of the disease and find better drug targets. miRNAs that were differentially expressed in Taxol-resistant ovarian cancer cells, compared with Taxol-sensitive cells, were screened by Illumina Human MicroRNA Expression BeadChips. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used to identify target genes of selected miRNAs. Kaplan–Meier survival analysis was applied to identify dysregulated miRNAs in ovarian cancer patients using data from The Cancer Genome Atlas. A total of 82 miRNAs were identified in ovarian carcinoma cells compared to normal ovarian cells. miR-141, miR-106a, miR-200c, miR-96, and miR-378 were overexpressed, and miR-411, miR-432, miR-494, miR-409-3p, and miR-655 were underexpressed in ovarian cancer cells. Seventeen miRNAs were overexpressed in Taxol-resistant cells, including miR-663, miR-622, and HS_188. Underexpressed miRNAs in Taxol-sensitive cells included miR-497, miR-187, miR-195, and miR-107. We further showed miR-663 and miR-622 as significant prognosis markers of the chemo-resistant patient group. In particular, the downregulation of the two miRNAs was associated with better survival, perhaps increasing the sensitivity of cancer cells to Taxol. In the chemo-sensitive patient group, only miR-647 could be a prognosis marker. These miRNAs inhibit several interacting genes of p53 networks, especially in TUOS-3 and TUOS-4, and showed cell line-specific inhibition effects. Taken together, the data indicate that the three miRNAs are closely associated with Taxol resistance and potentially better prognosis factors. Our results suggest that these miRNAs were successfully and reliably identified and would be used in the

  7. Urokinase receptor and CXCR4 are regulated by common microRNAs in leukaemia cells.

    PubMed

    Alfano, Daniela; Gorrasi, Anna; Li Santi, Anna; Ricci, Patrizia; Montuori, Nunzia; Selleri, Carmine; Ragno, Pia

    2015-09-01

    The urokinase-type plasminogen activator (uPA) receptor (uPAR) focuses uPA proteolytic activity on the cell membrane, promoting localized degradation of extracellular matrix (ECM), and binds vitronectin (VN), mediating cell adhesion to the ECM. uPAR-bound uPA and VN induce proteolysis-independent intracellular signalling, regulating cell adhesion, migration, survival and proliferation. uPAR cross-talks with CXCR4, the receptor for the stroma-derived factor 1 chemokine. CXCR4 is crucial in the trafficking of hematopoietic stem cells from/to the bone marrow, which involves also uPAR. Both uPAR and CXCR4 are expressed in acute myeloid leukaemia (AML), with a lower expression in undifferentiated and myeloid subsets, and higher expression in myelomonocytic and promyelocytic subsets. We hypothesized a microRNA (miR)-mediated co-regulation of uPAR and CXCR4 expression, which could allow their cross-talk at the cell surface. We identified three miRs, miR-146a, miR-335 and miR-622, regulating the expression of both uPAR and CXCR4 in AML cell lines. Indeed, these miRs directly target the 3'untranslated region of both uPAR- and CXCR4-mRNAs; accordingly, uPAR/CXCR4 expression is reduced by their overexpression in AML cells and increased by their specific inhibitors. Overexpression of all three miRs impairs migration, invasion and proliferation of myelomonocytic cells. Interestingly, we observed an inverse relationship between uPAR/CXCR4 expression and miR-146a and miR-335 levels in AML blasts, suggesting their possible role in the regulation of uPAR/CXCR4 expression also in vivo.

  8. Upregulation of microRNA-98 increases radiosensitivity in esophageal squamous cell carcinoma

    PubMed Central

    Jin, Ying-Ying; Chen, Qing-Juan; Wei, Yang; Wang, Ya-Li; Wang, Zhong-Wei; Xu, Kun; He, Yun; Ma, Hong-Bing

    2016-01-01

    Although radiation resistance is a common challenge in the clinical treatment of esophageal squamous cell carcinoma (ESCC), an effective treatment strategy has yet to be developed. Aberrant expression of microRNAs (miRNAs) is responsible for cancer sensitivity to radiation. In this study, we aimed to identify the miRNAs that are associated with radioresistance in ESCC. We used a miRNA microarray to perform a comparison of miRNA expression in both ESCC parental and acquired radioresistance cell lines. qRT-PCR was used to confirm the alterations. Cell radiosensitivity was determined with a survival fraction assay. Functional analyses of the identified miRNA in ESCC cells with regard to metastasis and apoptosis were performed by transwell assays and flow cytometry. The miRNA targets were identified with pathway analysis and confirmed with a luciferase assay. miR-98 was recognized as the most downregulated miRNA in established radioresistant cell line. AmiR-98 mimic enforced the expression of miRNA-98 and made ESCC cells sensitive to radiotherapy, while anti-miR-98 reversed this process. Optimal results were achieved by decreasing cellular proliferation, decreasing cell migration and inducing apoptosis. The luciferase target gene analysis results showed that the overexpression of miRNA-98 inhibited tumor growth and resistance tolerance by directly binding to the BCL-2 gene. Our study indicated that increasing miRNA-98 expression can be used as a potential radiosensitive therapeutic strategy for treating esophageal cancer cells. PMID:27422937

  9. Urokinase receptor and CXCR4 are regulated by common microRNAs in leukaemia cells

    PubMed Central

    Alfano, Daniela; Gorrasi, Anna; Li Santi, Anna; Ricci, Patrizia; Montuori, Nunzia; Selleri, Carmine; Ragno, Pia

    2015-01-01

    The urokinase-type plasminogen activator (uPA) receptor (uPAR) focuses uPA proteolytic activity on the cell membrane, promoting localized degradation of extracellular matrix (ECM), and binds vitronectin (VN), mediating cell adhesion to the ECM. uPAR-bound uPA and VN induce proteolysis-independent intracellular signalling, regulating cell adhesion, migration, survival and proliferation. uPAR cross-talks with CXCR4, the receptor for the stroma-derived factor 1 chemokine. CXCR4 is crucial in the trafficking of hematopoietic stem cells from/to the bone marrow, which involves also uPAR. Both uPAR and CXCR4 are expressed in acute myeloid leukaemia (AML), with a lower expression in undifferentiated and myeloid subsets, and higher expression in myelomonocytic and promyelocytic subsets. We hypothesized a microRNA (miR)-mediated co-regulation of uPAR and CXCR4 expression, which could allow their cross-talk at the cell surface. We identified three miRs, miR-146a, miR-335 and miR-622, regulating the expression of both uPAR and CXCR4 in AML cell lines. Indeed, these miRs directly target the 3′untranslated region of both uPAR- and CXCR4-mRNAs; accordingly, uPAR/CXCR4 expression is reduced by their overexpression in AML cells and increased by their specific inhibitors. Overexpression of all three miRs impairs migration, invasion and proliferation of myelomonocytic cells. Interestingly, we observed an inverse relationship between uPAR/CXCR4 expression and miR-146a and miR-335 levels in AML blasts, suggesting their possible role in the regulation of uPAR/CXCR4 expression also in vivo. PMID:26082201

  10. Predicting therapy response in live tumor cells isolated with the flexible micro spring array device

    PubMed Central

    Gallant, Jean-Nicolas; Matthew, Elizabeth M; Cheng, Hairong; Harouaka, Ramdane; Lamparella, Nicholas E.; Kunkel, Miriam; Yang, Zhaohai; Harvey, Harold A.; Cream, Leah V.; Kumar, Suresh M.; Robertson, Gavin P.; Zheng, Siyang; Drabick, Joseph J.; Truica, Cristina I.; El-Deiry, Wafik S.

    2013-01-01

    Cells disseminated from primary epithelial tumors into peripheral blood, called circulating tumor cells (CTCs), can be monitored to assess metastases and to provide a surrogate marker of treatment response. Here, we demonstrate how the flexible micro spring array (FMSA) device—a novel microfluidic device that enriches CTCs by two physical parameters: size and deformability—could be used in the rational development of treatment intervention and as a method to study the fundamental biology of CTCs. Cancer cells of different origins were spiked into healthy samples of donor blood to mimic blood samples of metastatic cancer patients. This spiked human blood was filtered using the FMSA device, and the recovered cells were successfully expanded in vitro and in a novel in vivo system. A series of experiments were performed to characterize these cells and to investigate the effect of chemotherapy on the resulting cultures. As few as 20 colon cancer cells in 7.5 mL blood could be isolated with the FMSA device, expanded both in vitro and in vivo and used at 25 cells per well to obtain significant and reliable chemosensitivity data. We also show that isolating a low number of viable patient CTCs and maintaining them in culture for a few weeks is possible. The isolation of viable cancer cells from human blood using the FMSA device provides a novel and realistic means for studying the biology of viable CTCs and for testing drug efficacy on these rare cells—a hypothesis that can be tested in future clinical trials. PMID:23759587

  11. Cancer mediates effector T cell dysfunction by targeting microRNAs and EZH2 via glycolysis restriction

    PubMed Central

    Zhao, Ende; Maj, Tomasz; Kryczek, Ilona; Li, Wei; Wu, Ke; Zhao, Lili; Wei, Shuang; Crespo, Joel; Wan, Shanshan; Vatan, Linda; Szeliga, Wojciech; Shao, Irene; Wang, Yin; Liu, Yan; Varambally, Sooryanarayana; Chinnaiyan, Arul M.; Welling, Theodore H.; Marquez, Victor E.; Kotarski, Jan; Wang, Hongbo; Wang, Zehua; Zhang, Yi; Liu, Rebecca; Wang, Guobin; Zou, Weiping

    2015-01-01

    Aerobic glycolysis regulates T cell function. However, if and how primary cancer alters T cell glycolytic metabolism and affects tumor immunity remains a question in cancer patients. Here we report that ovarian cancers imposed glucose restriction on T cells and dampened their function via maintaining high expression of microRNA101 and microRNA26a, which constrained expression of the methyltransferase EZH2. EZH2 activated the Notch pathway by suppressing Notch repressors, Numb and Fbxw7, via H3K27me3, and consequently stimulated T cell polyfunctional cytokine expression and promoted their survival via Bcl-2 signaling. Moreover, human shRNA-knockdown-EZH2-deficient T cells elicited poor anti-tumor immunity. EZH2+CD8+ T cells were associated with improved cancer patient survival. Together, the data unveil a novel metabolic target and mechanism of cancer immune evasion. PMID:26523864

  12. Application Of Micro-Highspeed Flow Visualization In Study Of Blood Cells Rheology In Vivo

    NASA Astrophysics Data System (ADS)

    Gui-shah, Li; Ni, Liang; Yu-ju, Lin; Jian, Zhang; Qiang, Wang

    1990-01-01

    A new experimental method has been developed in study of rheological behaviour of single red blood cell (RBC) in passing through the capillaries in vivo, using the technique of micro-highspeed cinecamera and micro-highspeed video system. It is one of the most important topics in the study of microcirculatory theories that fur-ther understand the deformability of RBC, flow states, velocities and dynamic mechanimi. A micro-highspeed flow visualization system consisted of essential elements: a biological microscope, a highspeed cinecmera with 35 mm film, a highspeed motion analysis system SP2000 (Kodak U.S.A) and a cold-light source etc. We have investigated the rheological parameters of single RBC in vivo in single capillaries which are about 3.3 to 6.9 um in diameters. The RBCs velocities are 0.1 to 0.25 mm/sec, and maximum shear stress on the outside surface of RBC is 13.8 dyn/cml, and maximum extension of RBC is 10.3 um. In aforementioned experiment, the highspeed flow visualization system frequency at 530 frames/sec and 200 frames/sec were used respectively. In addition, the vasomotion of precapillary sphincters have been measured and a complicated coupling phenomena between the RBC and sphincter have also been recorded and analysed. The experiment were performed with intravital hamsters and frogs. The results obtained by this system shown that the method designed by us are an effective tool in the study of rheological behaviour of single RBC in passing through the blood capillaries in vivoz.

  13. The CDX1–microRNA-215 axis regulates colorectal cancer stem cell differentiation

    PubMed Central

    Jones, Matthew F.; Hara, Toshifumi; Francis, Princy; Li, Xiao Ling; Bilke, Sven; Zhu, Yuelin; Pineda, Marbin; Subramanian, Murugan; Bodmer, Walter F.; Lal, Ashish

    2015-01-01

    The transcription factor caudal-type homeobox 1 (CDX1) is a key regulator of differentiation in the normal colon and in colorectal cancer (CRC). CDX1 activates the expression of enterocyte genes, but it is not clear how the concomitant silencing of stem cell genes is achieved. MicroRNAs (miRNAs) are important mediators of gene repression and have been implicated in tumor suppression and carcinogenesis, but the roles of miRNAs in differentiation, particularly in CRC, remain poorly understood. Here, we identified microRNA-215 (miR-215) as a direct transcriptional target of CDX1 by using high-throughput small RNA sequencing to profile miRNA expression in two pairs of CRC cell lines: CDX1-low HCT116 and HCT116 with stable CDX1 overexpression, and CDX1-high LS174T and LS174T with stable CDX1 knockdown. Validation of candidate miRNAs identified by RNA-seq in a larger cell-line panel revealed miR-215 to be most significantly correlated with CDX1 expression. Quantitative ChIP–PCR and promoter luciferase assays confirmed that CDX1 directly activates miR-215 transcription. miR-215 expression is depleted in FACS-enriched cancer stem cells compared with unsorted samples. Overexpression of miR-215 in poorly differentiated cell lines causes a decrease in clonogenicity, whereas miR-215 knockdown increases clonogenicity and impairs differentiation in CDX1-high cell lines. We identified the genome-wide targets of miR-215 and found that miR-215 mediates the repression of cell cycle and stemness genes downstream of CDX1. In particular, the miR-215 target gene BMI1 has been shown to promote stemness and self-renewal and to vary inversely with CDX1. Our work situates miR-215 as a link between CDX1 expression and BMI1 repression that governs differentiation in CRC. PMID:25775580

  14. Vapor and healing treatment for CH3NH3PbI(3-x)Cl(x) films toward large-area perovskite solar cells.

    PubMed

    Gouda, Laxman; Gottesman, Ronen; Tirosh, Shay; Haltzi, Eynav; Hu, Jiangang; Ginsburg, Adam; Keller, David A; Bouhadana, Yaniv; Zaban, Arie

    2016-03-28

    Hybrid methyl-ammonium lead trihalide perovskites are promising low-cost materials for use in solar cells and other optoelectronic applications. With a certified photovoltaic conversion efficiency record of 20.1%, scale-up for commercial purposes is already underway. However, preparation of large-area perovskite films remains a challenge, and films of perovskites on large electrodes suffer from non-uniform performance. Thus, production and characterization of the lateral uniformity of large-area films is a crucial step towards scale-up of devices. In this paper, we present a reproducible method for improving the lateral uniformity and performance of large-area perovskite solar cells (32 cm(2)). The method is based on methyl-ammonium iodide (MAI) vapor treatment as a new step in the sequential deposition of perovskite films. Following the MAI vapor treatment, we used high throughput techniques to map the photovoltaic performance throughout the large-area device. The lateral uniformity and performance of all photovoltaic parameters (V(oc), J(sc), Fill Factor, Photo-conversion efficiency) increased, with an overall improved photo-conversion efficiency of ∼100% following a vapor treatment at 140 °C. Based on XRD and photoluminescence measurements, We propose that the MAI treatment promotes a "healing effect" to the perovskite film which increases the lateral uniformity across the large-area solar cell. Thus, the straightforward MAI vapor treatment is highly beneficial for large scale commercialization of perovskite solar cells, regardless of the specific deposition method. PMID:26754034

  15. A Novel Technique for Micro-patterning Proteins and Cells on Polyacrylamide Gels

    PubMed Central

    Tang, Xin; Ali, M. Yakut; Saif, M. Taher A.

    2012-01-01

    Spatial patterning of proteins (extracellular matrix, ECM) for living cells on polyacrylamide (PA) hydrogels has been technically challenging due to the compliant nature of the hydrogels and their aqueous environment. Traditional micro-fabrication process is not applicable. Here we report a simple, novel and general method to pattern a variety of commonly used cell adhesion molecules, i.e. Fibronectin (FN), Laminin (LN) and Collagen I (CN), etc. on PA gels. The pattern is first printed on a hydrophilic glass using polydimethylsiloxane (PDMS) stamp and micro-contact printing (μCP). Pre-polymerization solution is applied on the patterned glass and is then sandwiched by a functionalized glass slide, which covalently binds to the gel. The hydrophilic glass slide is then peeled off from the gel when the protein patterns detach from the glass, but remain intact with the gel. The pattern is thus transferred to the gel. The mechanism of pattern transfer is studied in light of interfacial mechanics. It is found that hydrophilic glass offers strong enough adhesion with ECM proteins such that a pattern can be printed, but weak enough adhesion such that they can be completely peeled off by the polymerized gel. This balance is essential for successful pattern transfer. As a demonstration, lines of FN, LN and CN with widths varying from 5–400 μm are patterned on PA gels. Normal fibroblasts (MKF) are cultured on the gel surfaces. The cell attachment and proliferation are confined within these patterns. The method avoids the use of any toxic chemistry often used to pattern different proteins on gel surfaces. PMID:23002394

  16. MicroRNA and gene expression patterns in the differentiation of human embryonic stem cells

    PubMed Central

    Ren, Jiaqiang; Jin, Ping; Wang, Ena; Marincola, Francesco M; Stroncek, David F

    2009-01-01

    Background The unique features of human embryonic stem (hES) cells make them the best candidate resource for both cell replacement therapy and development research. However, the molecular mechanisms responsible for the simultaneous maintenance of their self-renewal properties and undifferentiated state remain unclear. Non-coding microRNAs (miRNA) which regulate mRNA cleavage and inhibit encoded protein translation exhibit temporal or tissue-specific expression patterns and they play an important role in development timing. Results In this study, we analyzed miRNA and gene expression profiles among samples from 3 hES cell lines (H9, I6 and BG01v), differentiated embryoid bodies (EB) derived from H9 cells at different time points, and 5 adult cell types including Human Microvascular Endothelial Cells (HMVEC), Human Umbilical Vein Endothelial Cells (HUVEC), Umbilical Artery Smooth Muscle Cells (UASMC), Normal Human Astrocytes (NHA), and Lung Fibroblasts (LFB). This analysis rendered 104 miRNAs and 776 genes differentially expressed among the three cell types. Selected differentially expressed miRNAs and genes were further validated and confirmed by quantitative real-time-PCR (qRT-PCR). Especially, members of the miR-302 cluster on chromosome 4 and miR-520 cluster on chromosome 19 were highly expressed in undifferentiated hES cells. MiRNAs in these two clusters displayed similar expression levels. The members of these two clusters share a consensus 7-mer seed sequence and their targeted genes had overlapping functions. Among the targeted genes, genes with chromatin structure modification function are enriched suggesting a role in the maintenance of chromatin structure. We also found that the expression level of members of the two clusters, miR-520b and miR-302c, were negatively correlated with their targeted genes based on gene expression analysis Conclusion We identified the expression patterns of miRNAs and gene transcripts in the undifferentiation of human embryonic

  17. MicroRNA-218 modulates activities of glioma cells by targeting HMGB1

    PubMed Central

    Gu, Jianjun; Xu, Rong; Li, Yaxing; Zhang, Jianhe; Wang, Shousen

    2016-01-01

    To explore the effects of microRNA-218 (miR-218) on glioma cell lines and the related mechanism. U251 and U87 cells were transfected with negative control, miR-218 mimic or miR-218 inhibitor using lipofectamine 2000. The expressions of mRNA and proteins were detected with qRT-PCR and Western blotting. The cell proliferation, apoptosis, migration and invasion were studied using MTT, flow cytometry, Transwell assay and scratch-wound assay, respectively. The targeting effect of HMGB1 by miR-218 was measured with luciferase reporter assay. The results showed that miR-218 was significantly downregulated while HMGB1 was upregulated in both glioma cell lines. Transfection of miR-218 significantly reduced the cell viability and colony formation, increased cell apoptosis and arrested cell in G0/G1 phase. Transfection of miR-218 also decreased the invasion and migration of glioma cells. The expressions of HMGB1, RAGE, cyclin D1 and MMP-9 were downregulated while the expression of caspase-9 was upregulated by miR-218. Silencing HMGB1 increased the expression of RAGE, cyclin D1, MMP-9 but decreased the expression of caspase-9 in U251 and U87 cells. Co-transfection with pcHMGB1 and miR-218 significantly decreased the growth inhibition and increased the apoptosis of glioma cells while these effects were abolished in glioma cells co-transfected with HMGB1 siRNA and miR-218 inhibitor. In addition, co-transfection with pcHMGB1 and miR-218 inhibitor increased the invasiveness of U251 and U87 cells. These findings suggested that miR-218 may negatively regulate HMGB-mediated suppression of RAGE to regulate cell proliferation, apoptosis and invasion, and that intervention of miR-218-HMGB1-RAGE may be useful for developing potential clinical strategies. PMID:27725858

  18. Micro gel column technique is fit for detecting mixed fields post ABO incompatible hematopoietic stem cell transplantation.

    PubMed

    Li, Min-Fang; Liu, Feng; Zhang, Min

    2015-04-01

    How to choose suitable serologic method for assessment of the actual stages of ABO chimera is more important to establish transfusion strategy for patients post-ABO incompatible hematopoietic stem cell transplantation. We reported ABO phenotypes of a patient post-ABO minor incompatible hematopoietic stem cell transplantation from 1+ weak agglutination by tube method was obviously reaffirmed to mixed fields with 4+ positive reaction by micro gel column card. Hence, blood bank technologists must continually work together with hematologist to establish appropriate transfusion strategy, and micro gel column technique can be more appropriate for detecting mixed fields during the whole period of transplantation. PMID:25578650

  19. MicroRNA-133a engineered mesenchymal stem cells augment cardiac function and cell survival in the infarct heart

    PubMed Central

    Dakhlallah, Duaa; Zhang, Jianying; Yu, Lianbo; Marsh, Clay B.; Angelos, Mark G.; Khan, Mahmood

    2015-01-01

    Cardiovascular disease is the number one cause of morbidity and mortality in the United States. The most common manifestation of cardiovascular disease is myocardial infarction (MI), which can ultimately lead to congestive heart failure (CHF). Cell therap (cardiomyoplasty) is a new potential therapeutic treatment alternative for the damaged heart. Recent preclinical and clinical studies have shown that mesenchymal stem cells (MSCs) are a promising cell type for cardiomyoplasty applications. However, a major limitation is the poor survival rate of transplanted stem cells in the infarcted heart. miR-133a is an abundantly expressed microRNA in the cardiac muscle and is down-regulated in patients with MI. We hypothesized that reprogramming MSCs using microRNA-mimics (double-stranded oligonucleotides) will improve survival of stem cells in the damaged heart. MSCs were transfected with miR-133a mimic and antagomirs and the levels of miR-133a were measured by qRT-PCR. Rat hearts were subjected to MI and MSCs transfected with miR-133a mimic or antagomir were implanted in the ischemic heart. Four weeks after MI, cardiac function, cardiac fibrosis, miR-133a levels and apoptosis related genes (Apaf-1, Capase-9 and Caspase-3) were measured in the heart. We found that transfecting MSCs with miR-133a mimic improves survival of MSCs as determined by the MTT assay. Similarly, transplantation of miR-133a mimic transfected MSCs in rat hearts subjected to MI led to a significant increase in cell engraftment, cardiac function and decreased fibrosis when compared with MSCs only or MI groups. At the molecular level, qRT-PCR data demonstrated a significant decrease in expression of the pro-apoptotic genes; Apaf-1, caspase-9 and caspase-3 in the miR-133a mimic transplanted group. Further, luciferase reporter assay confirmed that miR- 133a is a direct target for Apaf-1. Overall, bioengineering of stem cells through miRNAs manipulation could potentially improve the therapeutic outcome of

  20. High Throughput Single-cell and Multiple-cell Micro-encapsulation

    PubMed Central

    Lagus, Todd P.; Edd, Jon F.

    2012-01-01

    Microfluidic encapsulation methods have been previously utilized to capture cells in picoliter-scale aqueous, monodisperse drops, providing confinement from a bulk fluid environment with applications in high throughput screening, cytometry, and mass spectrometry. We describe a method to not only encapsulate single cells, but to repeatedly capture a set number of cells (here we demonstrate one- and two-cell encapsulation) to study both isolation and the interactions between cells in groups of controlled sizes. By combining drop generation techniques with cell and particle ordering, we demonstrate controlled encapsulation of cell-sized particles for efficient, continuous encapsulation. Using an aqueous particle suspension and immiscible fluorocarbon oil, we generate aqueous drops in oil with a flow focusing nozzle. The aqueous flow rate is sufficiently high to create ordering of particles which reach the nozzle at integer multiple frequencies of the drop generation frequency, encapsulating a controlled number of cells in each drop. For representative results, 9.9 μm polystyrene particles are used as cell surrogates. This study shows a single-particle encapsulation efficiency Pk=1 of 83.7% and a double-particle encapsulation efficiency Pk=2 of 79.5% as compared to their respective Poisson efficiencies of 39.3% and 33.3%, respectively. The effect of consistent cell and particle concentration is demonstrated to be of major importance for efficient encapsulation, and dripping to jetting transitions are also addressed. Introduction Continuous media aqueous cell suspensions share a common fluid environment which allows cells to interact in parallel and also homogenizes the effects of specific cells in measurements from the media. High-throughput encapsulation of cells into picoliter-scale drops confines the samples to protect drops from cross-contamination, enable a measure of cellular diversity within samples, prevent dilution of reagents and expressed biomarkers, and

  1. Experimental analysis of performance degradation of micro-tubular solid oxide fuel cells fed by different fuel mixtures

    NASA Astrophysics Data System (ADS)

    Calise, F.; Restucccia, G.; Sammes, N.

    This paper analyzes the thermodynamic and electrochemical dynamic performance of an anode supported micro-tubular solid oxide fuel cell (SOFC) fed by different types of fuel. The micro-tubular SOFC used is anode supported, consisting of a NiO and Gd 0.2Ce 0.8O 2- x (GDC) cermet anode, thin GDC electrolyte, and a La 0.6Sr 0.4Co 0.2Fe 0.8O 3- y (LSCF) and GDC cermet cathode. The fabrication of the cells under investigation is briefly summarized, with emphasis on the innovations with respect to traditional techniques. Such micro-tubular cells were tested using a Test Stand consisting of: a vertical tubular furnace, an electrical load, a galvanostast, a bubbler, gas pipelines, temperature, pressure and flow meters. The tests on the micro-SOFC were performed using H 2, CO, CH 4 and H 2O in different combinations at 550 °C, to determine the cell polarization curves under several load cycles. Long-term experimental tests were also performed in order to assess degradation of the electrochemical performance of the cell. Results of the tests were analyzed aiming at determining the sources of the cell performance degradation. Authors concluded that the cell under investigation is particularly sensitive to the carbon deposition which significantly reduces cell performance, after few cycles, when fed by light hydrocarbons. A significant performance degradation is also detected when hydrogen is used as fuel. In this case, the authors ascribe the degradation to the micro-cracks, the change in materials crystalline structure and problems with electrical connections.

  2. The MicroActive project: automatic detection of disease-related molecular cell activity

    NASA Astrophysics Data System (ADS)

    Furuberg, Liv; Mielnik, Michal; Johansen, Ib-Rune; Voitel, Jörg; Gulliksen, Anja; Solli, Lars; Karlsen, Frank; Bayer, Tobias; Schönfeld, Friedhelm; Drese, Klaus; Keegan, Helen; Martin, Cara; O'Leary, John; Riegger, Lutz; Koltay, Peter

    2007-05-01

    The aim of the MicroActive project is to develop an instrument for molecular diagnostics. The instrument will first be tested for patient screening for a group of viruses causing cervical cancer. Two disposable polymer chips with reagents stored on-chip will be inserted into the instrument for each patient sample. The first chip performs sample preparation of the epithelial cervical cells while mRNA amplification and fluorescent detection takes place in the second chip. More than 10 different virus markers will be analysed in one chip. We report results on sub-functions of the amplification chip. The sample is split into smaller droplets, and the droplets move in parallel channels containing different dried reagents for the different analyses. We report experimental results on parallel droplet movement control using one external pump only, combined with hydrophobic valves. Valve burst pressures are controlled by geometry. We show droplet control using valves with burst pressures between 800 and 4500 Pa. We also monitored the re-hydration times for two necessary dried reagents. After sample insertion, uniform concentration of the reagents in the droplet was reached after respectively 60 s and 10 min. These times are acceptable for successful amplification. Finally we have shown positive amplification of HPV type 16 using dried enzymes stored in micro chambers.

  3. MicroRNA-22 promotes cell survival upon UV radiation by repressing PTEN

    SciTech Connect

    Tan, Guangyun; Shi, Yuling; Wu, Zhao-Hui

    2012-01-06

    Highlights: Black-Right-Pointing-Pointer miR-22 is induced in cells treated with UV radiation. Black-Right-Pointing-Pointer ATM is required for miR-22 induction in response to UV. Black-Right-Pointing-Pointer miR-22 targets 3 Prime -UTR of PTEN to repress its expression in UV-treated cells. Black-Right-Pointing-Pointer Upregulated miR-22 inhibits apoptosis in cells exposed to UV. -- Abstract: DNA damage response upon UV radiation involves a complex network of cellular events required for maintaining the homeostasis and restoring genomic stability of the cells. As a new class of players involved in DNA damage response, the regulation and function of microRNAs in response to UV remain poorly understood. Here we show that UV radiation induces a significant increase of miR-22 expression, which appears to be dependent on the activation of DNA damage responding kinase ATM (ataxia telangiectasia mutated). Increased miR-22 expression may result from enhanced miR-22 maturation in cells exposed to UV. We further found that tumor suppressor gene phosphatase and tensin homolog (PTEN) expression was inversely correlated with miR-22 induction and UV-induced PTEN repression was attenuated by overexpression of a miR-22 inhibitor. Moreover, increased miR-22 expression significantly inhibited the activation of caspase signaling cascade, leading to enhanced cell survival upon UV radiation. Collectively, these results indicate that miR-22 is an important player in the cellular stress response upon UV radiation, which may promote cell survival via the repression of PTEN expression.

  4. Roles of microRNA-1 in hypoxia-induced apoptotic insults to neuronal cells.

    PubMed

    Chang, Chia-Yu; Lui, Tai-Ngar; Lin, Jia-Wei; Lin, Yi-Ling; Hsing, Chung-Hsi; Wang, Jhi-Joung; Chen, Ruei-Ming

    2016-01-01

    Hypoxia is a common occurrence in brain tumors and traumatic brain injury. microRNA (miR)-1 participates in the regulation of brain development and neuronal function. Interestingly, miR-1 can mediate ischemia-induced injury to cardiomyocytes. This study was designed to evaluate the roles of miR-1 in hypoxia-induced insults to neurons and the possible mechanisms. Exposure of neuro-2a cells to oxygen/glucose deprivation (OGD) or cobalt chloride decreased cell viability and induced cell apoptosis in time-dependent manners. In parallel, OGD caused augmentation of cellular Bax and cytochrome c levels, a reduction in the mitochondrial membrane potential (MMP), activation of caspase-3, and fragmentation of DNA. miR-1 was induced in neuro-2a cells by OGD. Knocking down miR-1 expression using specific antisense inhibitors significantly alleviated OGD-induced neuronal death. Administration of OGD to neuro-2a cells induced heat-shock protein (HSP)-70 messenger (m)RNA and protein expressions. A bioinformatic search revealed that miR-1-specific binding elements exist in the 3'-untranslated region of HSP-70 mRNA. Overexpression of miR-1 simultaneously attenuated OGD-induced HSP-70 mRNA and protein expressions. In comparison, knocking down miR-1 expression synergistically enhanced OGD-induced HSP-70 mRNA. As to the mechanism, reducing miR-1 expression lowered OGD-induced alterations in the MMP, caspase-3 activation, DNA fragmentation, and cell apoptosis. Taken together, this study shows that miR-1 can target HSP-70 expression and consequently mediate hypoxia-induced apoptotic insults to neuro-2a cells via an intrinsic Bax-mitochondrion-caspase protease pathway. PMID:25238743

  5. MicroRNA-141 inhibits glioma cells growth and metastasis by targeting TGF-β2

    PubMed Central

    Peng, Tao; Zhang, Shuyan; Li, Wenchen; Fu, Shuanglin; Luan, Yongxin; Zuo, Ling

    2016-01-01

    MicroRNA-141 (miR-141) has been reported to function as tumor suppressor in many types of cancer. However, the molecular function and underlying mechanisms of miR-141 in glioma is still unknown. The aims of this study were to investigate miR-141 expression and determine its biological function and underlying mechanism in glioma. In this study, we found that miR-141 expression levels, both in glioma cell lines and in tissues, were significantly lower than that in a normal human astrocyte cell line or adjacent non-cancerous tissues. Overexpression of miR-141 significantly inhibited glioma cell proliferation, colony formation, migration and invasion in vitro, as well as suppressed glioma tumor growth in vivo. In addition, transforming growth factor beta 2 (TGF-β2) was identified as a target of miR-141 in glioma cells. TGF-β2 expression was also found to be upregulated, and negatively associated with miR-141 in glioma tissues. TGF-β2 over-expression partly reversed the effect caused by transfection of miR-141 mimic. These findings together suggested that miR-141 functioned as tumor suppressor by targeting TGF-β2, and that miR-141 might be a promising therapeutic strategy for future treatment of glioma.

  6. MicroRNA-141 inhibits glioma cells growth and metastasis by targeting TGF-β2.

    PubMed

    Peng, Tao; Zhang, Shuyan; Li, Wenchen; Fu, Shuanglin; Luan, Yongxin; Zuo, Ling

    2016-01-01

    MicroRNA-141 (miR-141) has been reported to function as tumor suppressor in many types of cancer. However, the molecular function and underlying mechanisms of miR-141 in glioma is still unknown. The aims of this study were to investigate miR-141 expression and determine its biological function and underlying mechanism in glioma. In this study, we found that miR-141 expression levels, both in glioma cell lines and in tissues, were significantly lower than that in a normal human astrocyte cell line or adjacent non-cancerous tissues. Overexpression of miR-141 significantly inhibited glioma cell proliferation, colony formation, migration and invasion in vitro, as well as suppressed glioma tumor growth in vivo. In addition, transforming growth factor beta 2 (TGF-β2) was identified as a target of miR-141 in glioma cells. TGF-β2 expression was also found to be upregulated, and negatively associated with miR-141 in glioma tissues. TGF-β2 over-expression partly reversed the effect caused by transfection of miR-141 mimic. These findings together suggested that miR-141 functioned as tumor suppressor by targeting TGF-β2, and that miR-141 might be a promising therapeutic strategy for future treatment of glioma. PMID:27648141

  7. MicroRNAs and their target gene networks in renal cell carcinoma

    SciTech Connect

    Redova, Martina; Svoboda, Marek; Slaby, Ondrej

    2011-02-11

    Research highlights: {yields} MiRNAs are related to the processes of cell proliferation, apoptosis, angiogenesis, invasion, and metastasis in RCC. {yields} MiRNAs expression profiles are associated with several RCC-specific genetic alterations. {yields} It has been well documented that several miRNAs are downstream effector molecules of the HIF-induced hypoxia response. {yields} MiR-200 family is linked to epithelial-mesenchymal transition which is one of the most significant pathogenetic mechanism in RCC. {yields} Mechanistic studies in RCC have provided the rationale of using miRNAs as potential therapeutic targets. -- Abstract: MicroRNAs (miRNAs) are non-protein-coding short single stranded RNAs in the size range 19-25 nucleotides that are associated with gene regulation at the transcriptional and translation