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Sample records for lateral photovoltaic effect

  1. Large Lateral Photovoltaic Effect in Metal-(Oxide-) Semiconductor Structures

    PubMed Central

    Yu, Chongqi; Wang, Hui

    2010-01-01

    The lateral photovoltaic effect (LPE) can be used in position-sensitive detectors to detect very small displacements due to its output of lateral photovoltage changing linearly with light spot position. In this review, we will summarize some of our recent works regarding LPE in metal-semiconductor and metal-oxide-semiconductor structures, and give a theoretical model of LPE in these two structures. PMID:22163463

  2. Large lateral photovoltaic effect with ultrafast relaxation time in SnSe/Si junction

    NASA Astrophysics Data System (ADS)

    Wang, Xianjie; Zhao, Xiaofeng; Hu, Chang; Zhang, Yang; Song, Bingqian; Zhang, Lingli; Liu, Weilong; Lv, Zhe; Zhang, Yu; Tang, Jinke; Sui, Yu; Song, Bo

    2016-07-01

    In this paper, we report a large lateral photovoltaic effect (LPE) with ultrafast relaxation time in SnSe/p-Si junctions. The LPE shows a linear dependence on the position of the laser spot, and the position sensitivity is as high as 250 mV mm-1. The optical response time and the relaxation time of the LPE are about 100 ns and 2 μs, respectively. The current-voltage curve on the surface of the SnSe film indicates the formation of an inversion layer at the SnSe/p-Si interface. Our results clearly suggest that most of the excited-electrons diffuse laterally in the inversion layer at the SnSe/p-Si interface, which results in a large LPE with ultrafast relaxation time. The high positional sensitivity and ultrafast relaxation time of the LPE make the SnSe/p-Si junction a promising candidate for a wide range of optoelectronic applications.

  3. The lateral photovoltaic effect in CdS-Cu2S heterojunction solar cell

    NASA Astrophysics Data System (ADS)

    Islam, M. N.; Haque, M. A.

    1982-06-01

    The lateral photovoltaic effect has been observed in CdS-Cu2S thin-film solar cells. The effect is more pronounced on the CdS side than on the Cu2S side of the cells. On the CdS side, where the contacts were formed by soldering Cu wire by indium and then applying Ag paint, the photovoltage developed were found to increase as the point of illumination was moved towards the contact. The spectral response of photovoltage for coevaporated cells shows a peak at λ=0.5μm (2.45 eV). But for topotaxial cells two peaks, one at λ=0.5μm and the other at λ=0.65μm (1.89eV) were observed. A band model has been proposed for the heat-treated optimized cells.

  4. The lateral photovoltaic effect in CdS-Cu2S heterojunction solar cell

    NASA Astrophysics Data System (ADS)

    Islam, M. N.; Haque, M. A.

    1982-06-01

    The lateral photovoltaic effect has been observed in CdS-Cu2S thin-film solar cells. The effect is more pronounced on the CdS side than on the Cu2S side of the cells. On the CdS side, where the contacts were formed by soldering Cu wire by indium and then applying Ag paint, the photovoltage developed were found to increase as the point of illumination was moved towards the contact. The spectral response of photovoltage for coevaporated cells shows a peak at 0.5 micron (2.45 eV). But for topotaxial cells two peaks, one at 0.5 micron and the other at 0.65 micron (1.89 eV) were observed. A band model has been proposed for the heat-treated optimized cells.

  5. Large lateral photovoltaic effect observed in nano Al-doped ZnO films

    NASA Astrophysics Data System (ADS)

    Lu, Jing; Wang, Hui

    2011-07-01

    Zinc oxide (ZnO), including a variety of metal-doped ZnO, as one kind of most important photoelectric materials, has been widely investigated and received enormous attention for a series of applications. In this work, we report a new finding which we call as lateral photovoltaic effect (LPE) in a nano Al-doped ZnO (ZAO) film based on ZAO/SiO2/Si homo-heterostructure. This large and stable LPE observed in ZAO is an important supplement to the existing ZnO properties. In addition, all data and analyses demonstrate ZAO film can also be a good candidate for new type position-sensitive detector (PSD) devices.

  6. Transient lateral photovoltaic effect in patterned ferromagnetic metal-oxide-semiconductor films

    NASA Astrophysics Data System (ADS)

    Martinez, Isidoro; Cascales, Juan P.; Lara, Antonio; Andres, Pablo; Aliev, Farkhad G.

    2015-03-01

    The time dependent transient lateral photovoltaic effect (T-LPE) has been studied with microsecond time resolution and with chopping frequencies in the kHz range, in lithographically patterned 21 nm thick, 5, 10 and 20 micron wide and 1500 micron long Co lines grown over naturally passivated p-type Si (100). We have observed a nearly linear dependence of the LPE transient response with the laser spot position. An unusual T-LPE dynamic response with a sign change in the laser-off stage has also been corroborated by numerical simulations. A qualitative explanation suggests a modification of the drift-diffusion model by including the influence of a local inductance. In addition, influence of anisotropic magnetoresistance of the Co line structure on dynamic response on T-LPE has been investigated. Specifically, we have experimentally investigated influence of the direction of the external magnetic field respect to the drift velocity of the photogenerated carriers on the T-LPE. We have observed notable dependence of the T-LPE on the magnetic field in the small field range (below 100 Oe), compatible with anisotropic magnetoresistance values. The strong influence of the magnetization alignment on the dynamic response of photogenerated carriers has been also observed through a phase sensitive lock-in experiment. These findings indicate that the microstructuring of the ferromagnetic line based position sensitive detectors (PSD) could improve their space-time resolution and add capability of magnetic field tuning of the main PSD characteristics.

  7. Lateral photovoltaic effect co-observed with unipolar resistive switching behavior in Cu-doped ZnO film

    NASA Astrophysics Data System (ADS)

    Lu, Jing; Li, Zheng; Yin, Guilin; Ge, Meiying; He, Dannong; Wang, Hui

    2014-09-01

    Unipolar resistive switching (RS) behavior was first observed in Cu-doped ZnO film based on ZnO/SiO2/Si structure, which was a novel phenomenon as memory films grown on Si substrate usually showed a bipolar one. The results demonstrate Cu-doped ZnO a new candidate for memory material. By introducing an external electric-field before the sweeping process, we have verified that the RS behavior was a localized effect. The non-linear I-V character, which suggested a junction of the proposed Cu-doped ZnO/SiO2/Si structure, leads to the lateral photovoltaic effect (LPE) investigation. In photovoltaic mode, which is the simplest configuration, the position sensitivity of lateral photovoltage observed on Cu-doped ZnO film achieves 24.82 mV/mm and the nonlinearity is within 9.95%, indicating that Cu-doped ZnO could serve as a LPE material directly. The dual effects accommodate functions of detector and memristor in the same structure and make Cu-doped ZnO a competitive material for advanced multi-functional device.

  8. Large lateral photovoltaic effect in µc-SiOx:H/a-Si:H/c-Si p-i-n structure

    NASA Astrophysics Data System (ADS)

    Qiao, Shuang; Chen, Jianhui; Liu, Jihong; Zhang, Xinhui; Wang, Shufang; Fu, Guangsheng

    2016-03-01

    In this paper, we report on a large lateral photovoltaic effect (LPE) in a hydrogenated microcrystal silicon-oxygen (µc-SiOx:H)-based p-i-n structure. Compared with LPE in a hydrogenated amorphous silicon (a-Si:H)-based p-i-n structure, this structure showed an abnormal current-voltage (I-V) curve with a lower photoelectric conversion efficiency, but exhibited a much higher LPE with the highest position sensitivity of 64.3 mV/mm. We ascribe this to the enhancement of the lateral gradient of excess transmitted carriers induced by increasing both Schottky barrier and p-type layer body conductivity. Our results suggest that this µc-SiOx:H-based p-i-n structure may be a promising candidate for position-sensitive detectors (PSDs). Moreover, our results may also imply that solar cell devices with abnormal I-V curves (or low efficiency) could find their new applications in other aspects.

  9. Localized surface plasmon resonances dominated giant lateral photovoltaic effect observed in ZnO/Ag/Si nanostructure

    NASA Astrophysics Data System (ADS)

    Zhang, Ke; Wang, Hui; Gan, Zhikai; Zhou, Peiqi; Mei, Chunlian; Huang, Xu; Xia, Yuxing

    2016-03-01

    We report substantially enlarged lateral photovoltaic effect (LPE) in the ZnO/Ag/Si nanostructures. The maximum LPE sensitivity (55.05 mv/mm) obtained in this structure is about seven times larger than that observed in the control sample (7.88 mv/mm) of ZnO/Si. We attribute this phenomenon to the strong localized surface plasmon resonances (LSPRs) induced by nano Ag semicontinuous films. Quite different from the traditional LPE in PN junction type structures, in which light-generated carriers contributed to LPE merely depends on direct excitation of light in semiconductor, this work firstly demonstrates that, by introducing a super thin metal Ag in the interface between two different kinds of semiconductors, the nanoscale Ag embedded in the interface will produce strong resonance of localized field, causing extra intraband excitation, interband excitation and an enhanced direct excitation. As a consequence, these LSPRs dominated contributions harvest much more carriers, giving rise to a greatly enhanced LPE. In particular, this LSPRs-driven mechanism constitutes a sharp contrast to the traditional LPE operation mechanism. This work suggests a brand new LSPRs approach for tailoring LPE-based devices and also opens avenues of research within current photoelectric sensors area.

  10. Localized surface plasmon resonances dominated giant lateral photovoltaic effect observed in ZnO/Ag/Si nanostructure.

    PubMed

    Zhang, Ke; Wang, Hui; Gan, Zhikai; Zhou, Peiqi; Mei, Chunlian; Huang, Xu; Xia, Yuxing

    2016-01-01

    We report substantially enlarged lateral photovoltaic effect (LPE) in the ZnO/Ag/Si nanostructures. The maximum LPE sensitivity (55.05 mv/mm) obtained in this structure is about seven times larger than that observed in the control sample (7.88 mv/mm) of ZnO/Si. We attribute this phenomenon to the strong localized surface plasmon resonances (LSPRs) induced by nano Ag semicontinuous films. Quite different from the traditional LPE in PN junction type structures, in which light-generated carriers contributed to LPE merely depends on direct excitation of light in semiconductor, this work firstly demonstrates that, by introducing a super thin metal Ag in the interface between two different kinds of semiconductors, the nanoscale Ag embedded in the interface will produce strong resonance of localized field, causing extra intraband excitation, interband excitation and an enhanced direct excitation. As a consequence, these LSPRs dominated contributions harvest much more carriers, giving rise to a greatly enhanced LPE. In particular, this LSPRs-driven mechanism constitutes a sharp contrast to the traditional LPE operation mechanism. This work suggests a brand new LSPRs approach for tailoring LPE-based devices and also opens avenues of research within current photoelectric sensors area. PMID:26965713

  11. Localized surface plasmon resonances dominated giant lateral photovoltaic effect observed in ZnO/Ag/Si nanostructure

    PubMed Central

    Zhang, Ke; Wang, Hui; Gan, Zhikai; Zhou, Peiqi; Mei, Chunlian; Huang, Xu; Xia, Yuxing

    2016-01-01

    We report substantially enlarged lateral photovoltaic effect (LPE) in the ZnO/Ag/Si nanostructures. The maximum LPE sensitivity (55.05 mv/mm) obtained in this structure is about seven times larger than that observed in the control sample (7.88 mv/mm) of ZnO/Si. We attribute this phenomenon to the strong localized surface plasmon resonances (LSPRs) induced by nano Ag semicontinuous films. Quite different from the traditional LPE in PN junction type structures, in which light-generated carriers contributed to LPE merely depends on direct excitation of light in semiconductor, this work firstly demonstrates that, by introducing a super thin metal Ag in the interface between two different kinds of semiconductors, the nanoscale Ag embedded in the interface will produce strong resonance of localized field, causing extra intraband excitation, interband excitation and an enhanced direct excitation. As a consequence, these LSPRs dominated contributions harvest much more carriers, giving rise to a greatly enhanced LPE. In particular, this LSPRs-driven mechanism constitutes a sharp contrast to the traditional LPE operation mechanism. This work suggests a brand new LSPRs approach for tailoring LPE-based devices and also opens avenues of research within current photoelectric sensors area. PMID:26965713

  12. Photovoltaic switching mechanism in lateral structure hybrid perovskite solar cells

    DOE PAGESBeta

    Yuan, Yongbo; Chae, Jungseok; Shao, Yuchuan; Wang, Qi; Xiao, Zhengguo; Centrone, Andrea; Huang, Jinsong

    2015-06-05

    In this study, long range electromigration of methylammonium ions (MA+) in methyl ammonium lead tri-iodide (MAPbI3) film is observed directly using the photo­thermal induced resonance technique. The electromigration of MA+ leads to the formation of a lateral p-i-n structure, which is the origin of the switchable photovoltaic effect in MAPbI3 perovskite devices.

  13. Photovoltaic switching mechanism in lateral structure hybrid perovskite solar cells

    SciTech Connect

    Yuan, Yongbo; Chae, Jungseok; Shao, Yuchuan; Wang, Qi; Xiao, Zhengguo; Centrone, Andrea; Huang, Jinsong

    2015-06-05

    In this study, long range electromigration of methylammonium ions (MA+) in methyl ammonium lead tri-iodide (MAPbI3) film is observed directly using the photo­thermal induced resonance technique. The electromigration of MA+ leads to the formation of a lateral p-i-n structure, which is the origin of the switchable photovoltaic effect in MAPbI3 perovskite devices.

  14. Laterally inherently thin amorphous-crystalline silicon heterojunction photovoltaic cell

    SciTech Connect

    Chowdhury, Zahidur R. Kherani, Nazir P.

    2014-12-29

    This article reports on an amorphous-crystalline silicon heterojunction photovoltaic cell concept wherein the heterojunction regions are laterally narrow and distributed amidst a backdrop of well-passivated crystalline silicon surface. The localized amorphous-crystalline silicon heterojunctions consisting of the laterally thin emitter and back-surface field regions are precisely aligned under the metal grid-lines and bus-bars while the remaining crystalline silicon surface is passivated using the recently proposed facile grown native oxide–plasma enhanced chemical vapour deposited silicon nitride passivation scheme. The proposed cell concept mitigates parasitic optical absorption losses by relegating amorphous silicon to beneath the shadowed metallized regions and by using optically transparent passivation layer. A photovoltaic conversion efficiency of 13.6% is obtained for an untextured proof-of-concept cell illuminated under AM 1.5 global spectrum; the specific cell performance parameters are V{sub OC} of 666 mV, J{sub SC} of 29.5 mA-cm{sup −2}, and fill-factor of 69.3%. Reduced parasitic absorption, predominantly in the shorter wavelength range, is confirmed with external quantum efficiency measurement.

  15. Laterally inherently thin amorphous-crystalline silicon heterojunction photovoltaic cell

    NASA Astrophysics Data System (ADS)

    Chowdhury, Zahidur R.; Kherani, Nazir P.

    2014-12-01

    This article reports on an amorphous-crystalline silicon heterojunction photovoltaic cell concept wherein the heterojunction regions are laterally narrow and distributed amidst a backdrop of well-passivated crystalline silicon surface. The localized amorphous-crystalline silicon heterojunctions consisting of the laterally thin emitter and back-surface field regions are precisely aligned under the metal grid-lines and bus-bars while the remaining crystalline silicon surface is passivated using the recently proposed facile grown native oxide-plasma enhanced chemical vapour deposited silicon nitride passivation scheme. The proposed cell concept mitigates parasitic optical absorption losses by relegating amorphous silicon to beneath the shadowed metallized regions and by using optically transparent passivation layer. A photovoltaic conversion efficiency of 13.6% is obtained for an untextured proof-of-concept cell illuminated under AM 1.5 global spectrum; the specific cell performance parameters are VOC of 666 mV, JSC of 29.5 mA-cm-2, and fill-factor of 69.3%. Reduced parasitic absorption, predominantly in the shorter wavelength range, is confirmed with external quantum efficiency measurement.

  16. Giant switchable photovoltaic effect in organometal trihalide perovskite devices

    SciTech Connect

    Xiao, Zhengguo; Yuan, Yongbo; Shao, Yuchuan; Wang, Qi; Dong, Qingfeng; Bi, Cheng; Sharma, Pankaj; Gruverman, Alexei; Huang, Jinsong

    2014-12-08

    Organolead trihalide perovskite (OTP) materials are emerging as naturally abundant materials for low-cost, solution-processed and highly efficient solar cells. Here, we show that, in OTP-based photovoltaic devices with vertical and lateral cell configurations, the photocurrent direction can be switched repeatedly by applying a small electric field of <1 V μm–1. The switchable photocurrent, generally observed in devices based on ferroelectric materials, reached 20.1 mA cm–2 under one sun illumination in OTP devices with a vertical architecture, which is four orders of magnitude larger than that measured in other ferroelectric photovoltaic devices. This field-switchable photovoltaic effect can be explained by the formation of reversible p–i–n structures induced by ion drift in the perovskite layer. Furthermore, the demonstration of switchable OTP photovoltaics and electric-field-manipulated doping paves the way for innovative solar cell designs and for the exploitation of OTP materials in electrically and optically readable memristors and circuits.

  17. Giant switchable photovoltaic effect in organometal trihalide perovskite devices

    DOE PAGESBeta

    Xiao, Zhengguo; Yuan, Yongbo; Shao, Yuchuan; Wang, Qi; Dong, Qingfeng; Bi, Cheng; Sharma, Pankaj; Gruverman, Alexei; Huang, Jinsong

    2014-12-08

    Organolead trihalide perovskite (OTP) materials are emerging as naturally abundant materials for low-cost, solution-processed and highly efficient solar cells. Here, we show that, in OTP-based photovoltaic devices with vertical and lateral cell configurations, the photocurrent direction can be switched repeatedly by applying a small electric field of <1 V μm–1. The switchable photocurrent, generally observed in devices based on ferroelectric materials, reached 20.1 mA cm–2 under one sun illumination in OTP devices with a vertical architecture, which is four orders of magnitude larger than that measured in other ferroelectric photovoltaic devices. This field-switchable photovoltaic effect can be explained by themore » formation of reversible p–i–n structures induced by ion drift in the perovskite layer. Furthermore, the demonstration of switchable OTP photovoltaics and electric-field-manipulated doping paves the way for innovative solar cell designs and for the exploitation of OTP materials in electrically and optically readable memristors and circuits.« less

  18. Lateral Spectrum Splitting Concentrator Photovoltaics: Direct Measurement of Component and Submodule Efficiency

    SciTech Connect

    Xiaoting, W.; Waite, N.; Murcia, P.; Emery, K.; Steiner, M.; Kiamilev, F.; Goossen, K.; Honsberg, C.; Barnett, A.

    2012-03-01

    To achieve high energy conversion efficiency, a solar module architecture called lateral spectrum splitting concentrator photovoltaics (LSSCPV) is being developed. LSSCPV can concentrate available sunlight and laterally split a single beam into bands with different spectra for absorption by different solar cells with band gaps matched to the split spectrum. Test assemblies of a sample LSSCPV architecture were constructed, each of which contains four p-n junctions and two optical pieces. Independent experiments or simulations had been implemented on the components but by using optimal assumptions. In order to examine the actual performances of all the components, which are dependent on each other and the light source, direct outdoor measurements were made. A set of self-consistent efficiency definitions was articulated and a test bed was developed to measure the parameters required by the efficiency calculation. By comparing the component efficiency items derived from the outdoor measurement and the expected values based on independent simulations, the potential opportunities for efficiency improvement are determined. In the outdoor measurement at the University of Delaware, the optical component demonstrated 89.1% efficiency. Additional assemblies were tested at the National Renewable Energy Laboratory. One assembly demonstrated 36.7% submodule efficiency, which compares favorably with the 32.6% previously reported verified submodule efficiency.

  19. Substantial bulk photovoltaic effect enhancement via nanolayering.

    PubMed

    Wang, Fenggong; Young, Steve M; Zheng, Fan; Grinberg, Ilya; Rappe, Andrew M

    2016-01-01

    Spontaneous polarization and inversion symmetry breaking in ferroelectric materials lead to their use as photovoltaic devices. However, further advancement of their applications are hindered by the paucity of ways of reducing bandgaps and enhancing photocurrent. By unravelling the correlation between ferroelectric materials' responses to solar irradiation and their local structure and electric polarization landscapes, here we show from first principles that substantial bulk photovoltaic effect enhancement can be achieved by nanolayering PbTiO3 with nickel ions and oxygen vacancies ((PbNiO2)x(PbTiO3)(1-x)). The enhancement of the total photocurrent for different spacings between the Ni-containing layers can be as high as 43 times due to a smaller bandgap and photocurrent direction alignment for all absorption energies. This is due to the electrostatic effect that arises from nanolayering. This opens up the possibility for control of the bulk photovoltaic effect in ferroelectric materials by nanoscale engineering of their structure and composition. PMID:26791545

  20. Substantial bulk photovoltaic effect enhancement via nanolayering

    PubMed Central

    Wang, Fenggong; Young, Steve M.; Zheng, Fan; Grinberg, Ilya; Rappe, Andrew M.

    2016-01-01

    Spontaneous polarization and inversion symmetry breaking in ferroelectric materials lead to their use as photovoltaic devices. However, further advancement of their applications are hindered by the paucity of ways of reducing bandgaps and enhancing photocurrent. By unravelling the correlation between ferroelectric materials' responses to solar irradiation and their local structure and electric polarization landscapes, here we show from first principles that substantial bulk photovoltaic effect enhancement can be achieved by nanolayering PbTiO3 with nickel ions and oxygen vacancies ((PbNiO2)x(PbTiO3)1−x). The enhancement of the total photocurrent for different spacings between the Ni-containing layers can be as high as 43 times due to a smaller bandgap and photocurrent direction alignment for all absorption energies. This is due to the electrostatic effect that arises from nanolayering. This opens up the possibility for control of the bulk photovoltaic effect in ferroelectric materials by nanoscale engineering of their structure and composition. PMID:26791545

  1. Substantial bulk photovoltaic effect enhancement via nanolayering

    DOE PAGESBeta

    Wang, Fenggong; Young, Steve M.; Zheng, Fan; Grinberg, Ilya; Rappe, Andrew M.

    2016-01-21

    Spontaneous polarization and inversion symmetry breaking in ferroelectric materials lead to their use as photovoltaic devices. However, further advancement of their applications are hindered by the paucity of ways of reducing bandgaps and enhancing photocurrent. By unravelling the correlation between ferroelectric materials’ responses to solar irradiation and their local structure and electric polarization landscapes, here we show from first principles that substantial bulk photovoltaic effect enhancement can be achieved by nanolayering PbTiO3 with nickel ions and oxygen vacancies ((PbNiO2)x(PbTiO3)1–x). The enhancement of the total photocurrent for different spacings between the Ni-containing layers can be as high as 43 times duemore » to a smaller bandgap and photocurrent direction alignment for all absorption energies. This is due to the electrostatic effect that arises from nanolayering. Lastly, this opens up the possibility for control of the bulk photovoltaic effect in ferroelectric materials by nanoscale engineering of their structure and composition.« less

  2. Photovoltaics

    NASA Astrophysics Data System (ADS)

    Seippel, R. G.

    This book attempts to provide the reader with a cursory look at solar energy from a quarry of quartz to a sophisticated solar system. The progression of the theories of light is discussed along with the progression of photoelectricity, light rays, the optical spectrum, light reception, photodetection, aspects of photometry and radiometry, preferred terms in radiometric measurement, semiconductor physics, and light energy availability. Other subjects explored are related to manufacturing processes, photovoltaic materials, crystal growing, slicing techniques, wafer finishing, solar cell fabrication, photovoltaic cell types, concentrators, module fabrication, problems of quality assurance, photovoltaic systems, and the photovoltaics hierarchy. Attention is given to the polycrystalline cell, insulator cells, cadmium sulfide cells, amorphous silicon cells, an electrochemical cell, and the low-cost solar array project.

  3. Enlarging photovoltaic effect: combination of classic photoelectric and ferroelectric photovoltaic effects

    NASA Astrophysics Data System (ADS)

    Zhang, Jingjiao; Su, Xiaodong; Shen, Mingrong; Dai, Zhihua; Zhang, Lingjun; He, Xiyun; Cheng, Wenxiu; Cao, Mengyu; Zou, Guifu

    2013-07-01

    Converting light energy to electrical energy in photovoltaic devices relies on the photogenerated electrons and holes separated by the built-in potential in semiconductors. Photo-excited electrons in metal electrodes are usually not considered in this process. Here, we report an enhanced photovoltaic effect in the ferroelectric lanthanum-modified lead zirconate titanate (PLZT) by using low work function metals as the electrodes. We believe that electrons in the metal with low work function could be photo-emitted into PLZT and form the dominant photocurrent in our devices. Under AM1.5 (100 mW/cm2) illumination, the short-circuit current and open-circuit voltage of Mg/PLZT/ITO are about 150 and 2 times of those of Pt/PLZT/ITO, respectively. The photovoltaic response of PLZT capacitor was expanded from ultraviolet to visible spectra, and it may have important impact on design and fabrication of high performance photovoltaic devices based on ferroelectric materials.

  4. Enlarging photovoltaic effect: combination of classic photoelectric and ferroelectric photovoltaic effects

    PubMed Central

    Zhang, Jingjiao; Su, Xiaodong; Shen, Mingrong; Dai, Zhihua; Zhang, Lingjun; He, Xiyun; Cheng, Wenxiu; Cao, Mengyu; Zou, Guifu

    2013-01-01

    Converting light energy to electrical energy in photovoltaic devices relies on the photogenerated electrons and holes separated by the built-in potential in semiconductors. Photo-excited electrons in metal electrodes are usually not considered in this process. Here, we report an enhanced photovoltaic effect in the ferroelectric lanthanum-modified lead zirconate titanate (PLZT) by using low work function metals as the electrodes. We believe that electrons in the metal with low work function could be photo-emitted into PLZT and form the dominant photocurrent in our devices. Under AM1.5 (100 mW/cm2) illumination, the short-circuit current and open-circuit voltage of Mg/PLZT/ITO are about 150 and 2 times of those of Pt/PLZT/ITO, respectively. The photovoltaic response of PLZT capacitor was expanded from ultraviolet to visible spectra, and it may have important impact on design and fabrication of high performance photovoltaic devices based on ferroelectric materials. PMID:23811832

  5. Cost-effective applications of photovoltaics

    SciTech Connect

    Thornton, J.P.

    1996-05-01

    When photovoltaic (PV) cells were first developed at Bell Laboratories in the mid-1950s, their inventors envisioned widespread terrestrial use. However, PV cells were rapidly adopted for space applications, not only because of their reliability, but because they were generally the most cost- effective power sources for satellites in spite of their high cost. Concern over oil supply and price during the 1970s once again turned people`s thoughts toward the use of PV cells and other renewable energy technologies to help meet the nation`s energy demands. A partnership was developed between the federal government and private industry to drive the cost of PV technologies down to where they could compete in commercial markets. This partnership, which continues today, has been highly successful in achieving its goal. Today`s photovoltaic modules-more efficient and reliable than ever-have dropped to about 1/100th of their 1972 prices. From $500 or more per peak watt in those early days, module prices have dropped to about $5 per peak watt. Figure 1 illustrates the expansion of PV into commercial 2 effective markets as cost (and price) decreases. Once cost only in space, military, or consumer (primarily calculators and watches) applications, PV has now penetrated into both international and domestic markets. Currently cost-effective domestic uses, which are the primary subject of this paper, include applications in the residential, municipal, remote, and utility market sectors. The price of an installed PV system now ranges from $7 per watt to as high as $15 or $20 per watt, depending on factors such as the quantity purchased, size of the unit, amount of storage, and whether output is a.c. or d.c. This translates to a life-cycle energy cost of about 25 cents to 40 cents per kilowatt hour (kWh). Even at these seemingly high prices, PV technologies are gaining significant penetration into many U.S. markets.

  6. Photovoltaics effective capacity: Interim final report 2

    SciTech Connect

    Perez, R.; Seals, R.

    1997-11-01

    The authors provide solid evidence, based on more than 8 million data points, that regional photovoltaic (PV) effective capacity is largely unrelated to the region`s solar resource. They confirm, however, that effective capacity is strongly related to load-shape characteristics. The load-shape effective-capacity relationship appears to be valid for end-use loads as small as 100 kW, except possibly in the case of electrically heated buildings. This relationship was used as a tool to produce a US map of PV`s effective capacity. The regions of highest effective capacities include (1) the central US from the northern Great Plains to the metropolitan areas of Chicago and Detroit, down to the lower Mississippi Valley, (2) California and western Arizona, and (3) the northeast metropolitan corridor. The features of this map are considerably different from the traditional solar resource maps. They tend to reflect the socio-economic and climatic factors that indirectly drive PV`s effective capacity: e.g., commercial air-conditioning, little use of electric heat, and strong summer heat waves. The map provides a new and significant insight to a comprehensive valuation of the PV resource. The authors assembled preliminary evidence showing that end-use load type may be related to PV`s effective capacity. Highest effective capacities were found for (nonelectrically heated) office buildings, followed by hospitals. Lowest capacities were found for airports and residences. Many more data points are needed, however, to ascertain and characterize these preliminary findings.

  7. Field-effect-tuned lateral organic diodes

    PubMed Central

    Dhar, Bal Mukund; Kini, Geetha S.; Xia, Guoqiang; Jung, Byung Jun; Markovic, Nina; Katz, Howard E.

    2010-01-01

    The operation of organic diodes in solar cells and light-emitting displays strongly depends on the properties of the interfaces between hole- and electron-carrying organic semiconductors. Such interfaces are difficult to characterize, as they are usually buried under the surface or exist as an irregular “bulk heterojunction.” Using a unique fluorinated barrier layer-based lithographic technique, we fabricated a lateral organic p-n junction, allowing the first observation of the potential at an organic p-n interface simultaneously with the charge transport measurements. We find that the diode characteristics of the device (current output and rectification ratio) are consistent with the changes in the surface potentials near the junction, and the current-voltage curves and junction potentials are strongly and self-consistently modulated by a third, gate electrode. The generality of our technique makes this an attractive method to investigate the physics of organic semiconductor junctions. The lithographic technique is applicable to a wide variety of soft material patterns. The observation of built-in potentials makes an important connection between organic junctions and textbook descriptions of inorganic devices. Finally, these kinds of potentials may prove to be controlling factors in charge separation efficiency in organic photovoltaics. PMID:20160116

  8. Photovoltaics

    SciTech Connect

    Deb, S.K.

    1985-01-01

    Photovoltaics, the direct conversion of sunlight into electrical energy, may be the best hope for a relatively clean, secure, and inexhaustible source of energy for the future. To stimulate the growth of this technology as a viable energy supply option, considerable research and development has been directed, in both the private and public sectors, to a variety of materials and devices. The technology has sufficiently matured in recent years to be seriously considered as an alternative to conventional energy sources. Despite phenomenal advances in energy conversion efficiencies, many problems still remain to be solved. It is timely, therefore, to review various technological options available. This review critically assesses the status and promise of this emerging technology by a group of experts, each of whom has presented an extended invited paper on his specific field of expertise. This collection of presentations is intended to be an authoritative review of the technology including its developments, current status, and projections for future direction. The content of this review was carefully chosen to represent most of the leading state-of-the-art technologies; these are divided into four areas: (i) a general overview and discussion of silicon technology; (ii) high efficiency multijunction solar cells; (iii) amorphous silicon solar cells; and (iv) thin film compound semiconductors.

  9. New non-linear photovoltaic effect in uniform bipolar semiconductor

    SciTech Connect

    Volovichev, I.

    2014-11-21

    A linear theory of the new non-linear photovoltaic effect in the closed circuit consisting of a non-uniformly illuminated uniform bipolar semiconductor with neutral impurities is developed. The non-uniform photo-excitation of impurities results in the position-dependant current carrier mobility that breaks the semiconductor homogeneity and induces the photo-electromotive force (emf). As both the electron (or hole) mobility gradient and the current carrier generation rate depend on the light intensity, the photo-emf and the short-circuit current prove to be non-linear functions of the incident light intensity at an arbitrarily low illumination. The influence of the sample size on the photovoltaic effect magnitude is studied. Physical relations and distinctions between the considered effect and the Dember and bulk photovoltaic effects are also discussed.

  10. Photovoltaic Effect and Evidence of Carrier Multiplication in Graphene Vertical Homojunctions with Asymmetrical Metal Contacts.

    PubMed

    Chen, Jing-Jing; Wang, Qinsheng; Meng, Jie; Ke, Xiaoxing; Van Tendeloo, Gustaaf; Bie, Ya-Qing; Liu, Junku; Liu, Kaihui; Liao, Zhi-Min; Sun, Dong; Yu, Dapeng

    2015-09-22

    Graphene exhibits exciting potentials for high-speed wideband photodetection and high quantum efficiency solar energy harvest because of its broad spectral absorption, fast photoelectric response, and potential carrier multiplication. Although photocurrent can be generated near a metal-graphene interface in lateral devices, the photoactive area is usually limited to a tiny one-dimensional line-like interface region. Here, we report photoelectric devices based on vertical graphene two-dimensional homojunction, which is fabricated via vertically stacking four graphene monolayers with asymmetric metal contacts. The devices show excellent photovoltaic output with excitation wavelength ranging from visible light to mid-infrared. The wavelength dependence of the internal quantum efficiency gives direct evidence of the carrier multiplication effect in graphene. The simple fabrication process, easy scale-up, large photoresponsive active area, and broadband response of the vertical graphene device are very promising for practical applications in optoelectronics and photovoltaics. PMID:26279456

  11. Centrifugal photovoltaic and photogalvanic effects driven by structured light

    PubMed Central

    Wätzel, J.; Berakdar, J.

    2016-01-01

    Much efforts are devoted to material structuring in a quest to enhance the photovoltaic effect. We show that structuring light in a way it transfers orbital angular momentum to semiconductor-based rings results in a steady charge accumulation at the outer boundaries that can be utilized for the generation of an open circuit voltage or a photogalvanic (bulk photovoltaic) type current. This effect which stems both from structuring light and matter confinement potentials, can be magnified even at fixed moderate intensities, by increasing the orbital angular momentum of light which strengthens the effective centrifugal potential that repels the charge outwards. Based on a full numerical time propagation of the carriers wave functions in the presence of light pulses we demonstrate how the charge buildup leads to a useable voltage or directed photocurrent whose amplitudes and directions are controllable by the light pulse parameters. PMID:26900105

  12. Centrifugal photovoltaic and photogalvanic effects driven by structured light

    NASA Astrophysics Data System (ADS)

    Wätzel, J.; Berakdar, J.

    2016-02-01

    Much efforts are devoted to material structuring in a quest to enhance the photovoltaic effect. We show that structuring light in a way it transfers orbital angular momentum to semiconductor-based rings results in a steady charge accumulation at the outer boundaries that can be utilized for the generation of an open circuit voltage or a photogalvanic (bulk photovoltaic) type current. This effect which stems both from structuring light and matter confinement potentials, can be magnified even at fixed moderate intensities, by increasing the orbital angular momentum of light which strengthens the effective centrifugal potential that repels the charge outwards. Based on a full numerical time propagation of the carriers wave functions in the presence of light pulses we demonstrate how the charge buildup leads to a useable voltage or directed photocurrent whose amplitudes and directions are controllable by the light pulse parameters.

  13. Two-photon photovoltaic effect in gallium arsenide.

    PubMed

    Ma, Jichi; Chiles, Jeff; Sharma, Yagya D; Krishna, Sanjay; Fathpour, Sasan

    2014-09-15

    The two-photon photovoltaic effect is demonstrated in gallium arsenide at 976 and 1550 nm wavelengths. A waveguide-photodiode biased in its fourth quadrant harvests electrical power from the optical energy lost to two-photon absorption. The experimental results are in good agreement with simulations based on nonlinear wave propagation in waveguides and the drift-diffusion model of carrier transport in semiconductors. Power efficiency of up to 8% is theoretically predicted in optimized devices. PMID:26466255

  14. Photovoltaic Effect in an Electrically Tunable van der Waals Heterojunction

    PubMed Central

    2014-01-01

    Semiconductor heterostructures form the cornerstone of many electronic and optoelectronic devices and are traditionally fabricated using epitaxial growth techniques. More recently, heterostructures have also been obtained by vertical stacking of two-dimensional crystals, such as graphene and related two-dimensional materials. These layered designer materials are held together by van der Waals forces and contain atomically sharp interfaces. Here, we report on a type-II van der Waals heterojunction made of molybdenum disulfide and tungsten diselenide monolayers. The junction is electrically tunable, and under appropriate gate bias an atomically thin diode is realized. Upon optical illumination, charge transfer occurs across the planar interface and the device exhibits a photovoltaic effect. Advances in large-scale production of two-dimensional crystals could thus lead to a new photovoltaic solar technology. PMID:25057817

  15. Cerebral Lateralization and Its Effect on Drawing.

    ERIC Educational Resources Information Center

    Thomas, Yvonne A.; Thomas, Stephen B.

    1983-01-01

    Discusses the importance of both sides of the brain for the development of drawing skills but notes that the left brain can inhibit the action of the right brain. Provides a discussion of cerebral lateralization and child development. Suggests five drawing exercises to help develop hemispheric cooperation. (SB)

  16. Photovoltaic effect in Bi{sub 2}TeO{sub 5} photorefractive crystal

    SciTech Connect

    Oliveira, Ivan de Capovilla, Danilo Augusto

    2015-10-12

    We report on the presence of a strong photovoltaic effect on nominally undoped photorefractive Bi{sub 2}TeO{sub 5} crystals and estimated their Glass photovoltaic constant and photovoltaic field for λ = 532 nm illumination. We directly measured the photovoltaic-based photocurrent in this material under λ = 532 nm wavelength laser light illumination and compared its behavior with that of a well known photovoltaic Fe-doped Lithium Niobate crystal. We also show the photovoltaic current to strongly depend on the polarization direction of light. Holographic diffraction efficiency oscillation during recording and the behavior of fringe-locked running holograms in self-stabilized experiments are also demonstrated here as additional indirect proofs of the photovoltaic nature of this material.

  17. Photovoltaic chiral magnetic effect in Weyl semimetals

    NASA Astrophysics Data System (ADS)

    Taguchi, Katsuhisa; Imaeda, Tatsushi; Sato, Masatoshi; Tanaka, Yukio

    2016-05-01

    We theoretically predict current generation in Weyl semimetals when circularly polarized light is applied. The electric field of the light can drive an effective magnetic field on the order of 10 T. For lower-frequency light, a nonequilibrium spin distribution is formed near the Fermi surface. Spin-momentum locking induces a giant electric current proportional to the effective magnetic field. In contrast, higher-frequency light realizes a quasistatic Floquet state with no induced electric current. We discuss the relevant materials and estimate the order of magnitude of the induced current.

  18. Photovoltaics for municipal planners. Cost-effective municipal applications of photovoltaics for electric power

    SciTech Connect

    Not Available

    1993-04-01

    This booklet is intended for city and county government personnel, as well as community organizations, who deal with supplying, regulating, or recommending electric power resources. Specifically, this document deals with photovoltaic (PV) power, or power from solar cells, which is currently the most cost-effective energy source for electricity requirements that are relatively small, located in isolated areas, or difficult to serve with conventional technology. Recently, PV has been documented to be more cost-effective than conventional alternatives (such as line extensions or engine generators) in dozens of applications within the service territories of electric, gas, and communications utilities. Here, we document numerous cost-effective urban applications, chosen by planners and utilities because they were the most cost-effective option or because they were appropriate for environmental or logistical reasons. These applications occur within various municipal departments, including utility, parks and recreation, traffic engineering, transportation, and planning, and they include lighting applications, communications equipment, corrosion protection, irrigation control equipment, remote monitoring, and even portable power supplies for emergency situations.

  19. Electrochemical aging effects in photovoltaic modules

    NASA Technical Reports Server (NTRS)

    Mon, G. R.

    1986-01-01

    Leakage currents were experimentally measured in PV modules undergoing natural aging outdoors, and in PV modules undergoing accelerated aging in laboratory environmental chambers. The significant contributors to module leakage current were identified with a long range goal to develop techniques to reduce or stop module leakage currents. For outdoor aging in general, module leakage current is relatively insensitive to temperature fluctuations, but is very sensitive to moisture effects such as dew, precipitation, and fluctuations in relative humidity. Comparing ethylene vinyl acetate (EVA) and polyvinyl butyral (PVB), module leakage currents are much higher in PVB as compared to EVA for all environmental conditions investigated. Leakage currents proceed in series along two paths, bulk conduction followed by interfacial (surfaces) conduction.

  20. Pattern Effects of Soil on Photovoltaic Surfaces

    DOE PAGESBeta

    Burton, Patrick D.; Hendrickson, Alex; Ulibarri, Stephen Seth; Riley, Daniel; Boyson, William E.; King, Bruce H.

    2016-06-06

    The texture or patterning of soil on PV surfaces may influence light capture at various angles of incidence (AOI). Accumulated soil can be considered a microshading element, which changes with respect to AOI. Laboratory deposition of simulated soil was used to prepare test coupons for simultaneous AOI and soiling loss experiments. A mixed solvent deposition technique was used to consistently deposit patterned test soils onto glass slides. Transmission decreased as soil loading and AOI increased. Dense aggregates significantly decreased transmission. But, highly dispersed particles are less prone to secondary scattering, improving overall light collection. In order to test AOI losses on relevant systems, uniform simulated soil coatings were applied to split reference cells to further examine this effect. Finally, the measured optical transmission and area coverage correlated closely to the observedmore » $$I_{{rm SC}}$$. Angular losses were significant at angles as low as 25°.« less

  1. Effective Lateral Canthal Lengthening with Triangular Rotation Flap

    PubMed Central

    2016-01-01

    In Korea, lateral canthoplasty, along with medial epicanthoplasty, has become popular over the past years to widen the horizontal length of the palpebral fissure. However, the effect of the surgery differs greatly depending on the shape and structure of the eyes. If over-widened, complications such as eversion, scarring, and conjunctival exposure may occur. Thus, the author of this study suggests a more effective and safe method for lateral canthal lengthening that causes minimal complications. A total of 236 patients underwent lateral canthoplasty between July 2007 and December 2015. For each patient, a triangular flap 4–5 mm away from the lateral canthus was elevated and rotated 45 degrees laterally while the continuity of the lower eyelid gray line was maintained. A new lateral canthus was created by fixating the rotation flap to the lateral orbital rim with minimal skin trimming and tension-free sutures, preventing relapse and maintaining a triangular shape. In more than 95% of cases, effective and satisfactory extension was achieved. On average, a 3 mm extension of the lateral canthus was achieved. There were minor complications such as wound dehiscence, webbing, and scarring, which were easily corrected. The author not only extended the lateral canthus 3–4 mm laterally but also maintained the continuity of the gray line on the lower lid as a more natural-looking triangular shape, while minimizing complications such as webbing and conjunctival exposure. PMID:27462562

  2. Optical cleaning owing to the bulk photovoltaic effect

    NASA Astrophysics Data System (ADS)

    Sturman, B.; Kösters, M.; Haertle, D.; Becher, C.; Buse, K.

    2009-12-01

    It is shown within the conventional photovoltaic charge-transport model that photoexcitable electrons, localized at deep impurity levels, can be effectively removed by light from the exposed area at sufficiently high temperatures. This allows to modify strongly the absorption and photoelectric properties of the material and, in particular, to suppress “optical damage” in LiNbO3 and LiTaO3 crystals. This optical cleaning method is applicable to numerous pyro- and piezo-electric optical materials. It employs the photovoltaic drift of electrons and ionic charge compensation at elevated temperatures. The physics of the optical cleaning is very rich; it has strong links to nonlinear dynamics and offers important handles for improvement of the cleaning performance. The use of properly moving light beams leads, e.g., to a strong enhancement of the cleaning rate and allows to reduce the electron concentration by several orders of magnitude. The theoretical predictions are supported by the data of our cleaning experiments with LiNbO3 crystals. In particular, the intensity threshold of optical damage is increased by three orders of magnitude.

  3. Effect of COOH-functionalized SWCNT addition on the electrical and photovoltaic characteristics of Malachite Green dye based photovoltaic cells

    NASA Astrophysics Data System (ADS)

    Chakraborty, S.; Manik, N. B.

    2014-12-01

    We report the effect of COOH-functionalized single walled carbon nanotubes (COOH-SWCNT) on the electrical and photovoltaic characteristics of Malachite Green (MG) dye based photovoltaic cells. Two different types of photovoltaic cells were prepared, one with MG dye and another by incorporating COOH-SWCNT with this dye. Cells were characterized through different electrical and photovoltaic measurements including photocurrent measurements with pulsed radiation. From the dark current—voltage (I-V) characteristic results, we observed a certain transition voltage (Vth) for both the cells beyond which the conduction mechanism of the cells change sharply. For the MG dye, Vth is 3.9 V whereas for COOH-SWCNT mixed with this dye, Vth drops to 2.7 V. The device performance improves due to the incorporation of COOH-SWCNT. The open circuit voltage and short circuit current density change from 4.2 to 97 mV and from 108 to 965 μA/cm2 respectively. Observations from photocurrent measurements show that the rate of growth and decay of the photocurrent are quite faster in the presence of COOH-SWCNT. This observation indicates a faster charge separation processes due to the incorporation of COOH-SWCNT in the MG dye cells. The high aspect ratio of COOH-SWCNT allows efficient conduction pathways for the generated charge carriers.

  4. Photovoltaic effect in individual asymmetrically contacted lead sulfide nanosheets.

    PubMed

    Dogan, Sedat; Bielewicz, Thomas; Lebedeva, Vera; Klinke, Christian

    2015-03-21

    Solution-processable, two-dimensional semiconductors are promising optoelectronic materials which could find application in low-cost solar cells. Lead sulfide nanocrystals raised attention since the effective band gap can be adapted over a wide range by electronic confinement and observed multi-exciton generation promises higher efficiencies. We report on the influence of the contact metal work function on the properties of transistors based on individual two-dimensional lead sulfide nanosheets. Using palladium we observed mobilities of up to 31 cm(2) V(-1) s(-1). Furthermore, we demonstrate that asymmetrically contacted nanosheets show photovoltaic effect and that the nanosheets' height has a decisive impact on the device performance. Nanosheets with a thickness of 5.4 nm contacted with platinum and titanium show a power conversion efficiency of up to 0.94% (EQE 75.70%). The results underline the high hopes put on such materials. PMID:25673356

  5. Photovoltaic effect in individual asymmetrically contacted lead sulfide nanosheets

    NASA Astrophysics Data System (ADS)

    Dogan, Sedat; Bielewicz, Thomas; Lebedeva, Vera; Klinke, Christian

    2015-03-01

    Solution-processable, two-dimensional semiconductors are promising optoelectronic materials which could find application in low-cost solar cells. Lead sulfide nanocrystals raised attention since the effective band gap can be adapted over a wide range by electronic confinement and observed multi-exciton generation promises higher efficiencies. We report on the influence of the contact metal work function on the properties of transistors based on individual two-dimensional lead sulfide nanosheets. Using palladium we observed mobilities of up to 31 cm2 V-1 s-1. Furthermore, we demonstrate that asymmetrically contacted nanosheets show photovoltaic effect and that the nanosheets' height has a decisive impact on the device performance. Nanosheets with a thickness of 5.4 nm contacted with platinum and titanium show a power conversion efficiency of up to 0.94% (EQE 75.70%). The results underline the high hopes put on such materials.Solution-processable, two-dimensional semiconductors are promising optoelectronic materials which could find application in low-cost solar cells. Lead sulfide nanocrystals raised attention since the effective band gap can be adapted over a wide range by electronic confinement and observed multi-exciton generation promises higher efficiencies. We report on the influence of the contact metal work function on the properties of transistors based on individual two-dimensional lead sulfide nanosheets. Using palladium we observed mobilities of up to 31 cm2 V-1 s-1. Furthermore, we demonstrate that asymmetrically contacted nanosheets show photovoltaic effect and that the nanosheets' height has a decisive impact on the device performance. Nanosheets with a thickness of 5.4 nm contacted with platinum and titanium show a power conversion efficiency of up to 0.94% (EQE 75.70%). The results underline the high hopes put on such materials. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr06957a

  6. Photovoltaic effect in transition metal modified polycrystalline BiFeO3 thin films

    NASA Astrophysics Data System (ADS)

    Sreenivas Puli, Venkata; Pradhan, Dhiren Kumar; Katiyar, Rajesh Kumar; Coondoo, Indrani; Panwar, Neeraj; Misra, Pankaj; Chrisey, Douglas B.; Scott, J. F.; Katiyar, Ram S.

    2014-02-01

    We report photovoltaic (PV) effect in multiferroic Bi0.9Sm0.1Fe0.95Co0.05O3 (BSFCO) thin films. Transition metal modified polycrystalline BiFeO3 (BFO) thin films have been deposited on Pt/TiO2/SiO2/Si substrate successfully through pulsed laser deposition (PLD). PV response is observed under illumination both in sandwich and lateral electrode configurations. The open-circuit voltage (Voc) and the short-circuit current density (Jsc) of the films in sandwich electrode configuration under illumination are measured to be 0.9 V and -0.051 µA cm-2. Additionally, we report piezoresponse for BSFCO films, which confirms ferroelectric piezoelectric behaviour.

  7. Manganite-based heterojunction and its photovoltaic effects

    NASA Astrophysics Data System (ADS)

    Sun, J. R.; Xiong, C. M.; Shen, B. G.; Wang, P. Y.; Weng, Y. X.

    2004-04-01

    A heterojunction is fabricated by growing a La0.29Pr0.38Ca0.33MnO3 (LPCM) film on the 0.5 wt % Nb-doped SrTiO3 (STON) substrate, and its properties have been experimentally studied. In addition to fairly good rectifying behavior, the heterojunction exhibits a significant photovoltaic effect. The photovoltage on the two electrodes LPCM and STON increases almost linearly with the power of the laser beam (λ=532 nm) at a rate of ˜0.19 V/W, and no tendency to saturation is observed up to the light power of 100 mW. The lifetime of the extra carriers is between 7 and 9 ms (slightly pulse laser energy dependent), obtained from the decay of photovoltage after shutting down light illumination. The present work shows a great potential of the manganite-based heterojunction as photoelectric devices.

  8. Predicting the Spectral Effects of Soils on Concentrating Photovoltaic Systems

    DOE PAGESBeta

    Burton, Patrick D.; King, Bruce Hardison; Riley, Daniel M.

    2014-12-15

    The soiling losses on high concentrating photovoltaic (HCPV) systems may be influenced by the spectral properties of accumulated soil. We predicted the response of an isotype cell to changes in spectral content and reduction in transmission due to soiling using measured UV/vis transmittance through soil films. Artificial soil test blends deposited on glass coupons were used to supply the transmission data, which was then used to calculate the effect on model spectra. Moreover, the wavelength transparency of the test soil was varied by incorporating red and yellow mineral pigments into graded sand. The more spectrally responsive (yellow) soils were predictedmore » to alter the current balance between the top and middle subcells throughout a range of air masses corresponding to daily and seasonal variation.« less

  9. Predicting the Spectral Effects of Soils on Concentrating Photovoltaic Systems

    SciTech Connect

    Burton, Patrick D.; King, Bruce Hardison; Riley, Daniel M.

    2014-12-15

    The soiling losses on high concentrating photovoltaic (HCPV) systems may be influenced by the spectral properties of accumulated soil. We predicted the response of an isotype cell to changes in spectral content and reduction in transmission due to soiling using measured UV/vis transmittance through soil films. Artificial soil test blends deposited on glass coupons were used to supply the transmission data, which was then used to calculate the effect on model spectra. Moreover, the wavelength transparency of the test soil was varied by incorporating red and yellow mineral pigments into graded sand. The more spectrally responsive (yellow) soils were predicted to alter the current balance between the top and middle subcells throughout a range of air masses corresponding to daily and seasonal variation.

  10. Non-volatile memory based on the ferroelectric photovoltaic effect

    PubMed Central

    Guo, Rui; You, Lu; Zhou, Yang; Shiuh Lim, Zhi; Zou, Xi; Chen, Lang; Ramesh, R.; Wang, Junling

    2013-01-01

    The quest for a solid state universal memory with high-storage density, high read/write speed, random access and non-volatility has triggered intense research into new materials and novel device architectures. Though the non-volatile memory market is dominated by flash memory now, it has very low operation speed with ~10 μs programming and ~10 ms erasing time. Furthermore, it can only withstand ~105 rewriting cycles, which prevents it from becoming the universal memory. Here we demonstrate that the significant photovoltaic effect of a ferroelectric material, such as BiFeO3 with a band gap in the visible range, can be used to sense the polarization direction non-destructively in a ferroelectric memory. A prototype 16-cell memory based on the cross-bar architecture has been prepared and tested, demonstrating the feasibility of this technique. PMID:23756366

  11. The Effects of Enriched Neonatal Experiences Upon Later Cognitive Functioning

    ERIC Educational Resources Information Center

    Wachs, Theodore D.; Cucinotta, Pattiann

    1971-01-01

    The data reported in this small study confirm previous research indicating that early stimulation, though initially affecting human behavior, has little permanent effect upon later functioning. (Author/WY)

  12. Effects of a continuous lateral turning device on pressure relief.

    PubMed

    Do, Nam Ho; Kim, Deog Young; Kim, Jung-Hoon; Choi, Jong Hyun; Joo, So Young; Kang, Na Kyung; Baek, Yoon Su

    2016-01-01

    [Purpose] The purpose of this study was to examine the pressure-relieving effects of a continuous lateral turning device on common pressure ulcer sites. [Subjects] Twenty-four healthy adults participated. [Methods] The design of our continuous lateral turning device was motivated by the need for an adequate pressure-relieving device for immobile and/or elderly people. The procedure of manual repositioning is embodied in our continuous lateral turning device. The interface pressure and time were measured, and comfort grade was evaluated during sessions of continuous lateral turning at 0°, 15°, 30°, and 45°. We quantified the pressure-relieving effect using peak pressure, mean pressure, and pressure time integration. [Results] Participants demonstrated pressure time integration values below the pressure-time threshold at 15°, 30°, and 45° at all the common pressure ulcer sites. Moreover, the most effective angles for pressure relief at the common pressure ulcer sites were 30° at the occiput, 15° at the left scapula, 45° at the right scapula, 45° at the sacrum, 15° at the right heel, and 30° at the left heel. However, angles greater than 30° induced discomfort. [Conclusion] Continuous lateral turning with our specially designed device effectively relieved the pressure of targeted sites. Moreover, the suggested angles of continuous lateral turning can be used to relieve pressure at targeted sites. PMID:27065531

  13. Effects of a continuous lateral turning device on pressure relief

    PubMed Central

    Do, Nam Ho; Kim, Deog Young; Kim, Jung-Hoon; Choi, Jong Hyun; Joo, So Young; Kang, Na Kyung; Baek, Yoon Su

    2016-01-01

    [Purpose] The purpose of this study was to examine the pressure-relieving effects of a continuous lateral turning device on common pressure ulcer sites. [Subjects] Twenty-four healthy adults participated. [Methods] The design of our continuous lateral turning device was motivated by the need for an adequate pressure-relieving device for immobile and/or elderly people. The procedure of manual repositioning is embodied in our continuous lateral turning device. The interface pressure and time were measured, and comfort grade was evaluated during sessions of continuous lateral turning at 0°, 15°, 30°, and 45°. We quantified the pressure-relieving effect using peak pressure, mean pressure, and pressure time integration. [Results] Participants demonstrated pressure time integration values below the pressure-time threshold at 15°, 30°, and 45° at all the common pressure ulcer sites. Moreover, the most effective angles for pressure relief at the common pressure ulcer sites were 30° at the occiput, 15° at the left scapula, 45° at the right scapula, 45° at the sacrum, 15° at the right heel, and 30° at the left heel. However, angles greater than 30° induced discomfort. [Conclusion] Continuous lateral turning with our specially designed device effectively relieved the pressure of targeted sites. Moreover, the suggested angles of continuous lateral turning can be used to relieve pressure at targeted sites. PMID:27065531

  14. Magnetoelectric, photovoltaic, and magnetophotovoltaic effects in KBiF e2O5

    NASA Astrophysics Data System (ADS)

    Mettout, B.; Tolédano, P.; Sombra, A. S. B.; Furtado Filho, A. F. G.; do Nascimento, J. P. C.; Santos da Silva, M. A.; Gisse, P.; Vasseur, H.

    2016-05-01

    Multiferroic materials are intensively investigated as potential candidates for a new generation of solar cells, due to the coexistence in their phases of ferroelectricity and magnetic order with low band gap. However, symmetry considerations, which determine the interplay between the magnetoelectric and photovoltaic properties of a light irradiated multiferroic crystal, are not fully taken into account in the current theory of the photovoltaic effect. Here the remarkable photovoltaic and magnetophotovoltaic effects occurring in the multiferroic phase of KBiF e2O5 are described using a theoretical approach that takes directly into account the crystal and light beam wave symmetries.

  15. Cost effective flat plate photovoltaic modules using light trapping

    NASA Technical Reports Server (NTRS)

    Bain, C. N.; Gordon, B. A.; Knasel, T. M.; Malinowski, R. L.

    1981-01-01

    Work in optical trapping in 'thick films' is described to form a design guide for photovoltaic engineers. A thick optical film can trap light by diffusive reflection and total internal reflection. Light can be propagated reasonably long distances compared with layer thicknesses by this technique. This makes it possible to conduct light from inter-cell and intra-cell areas now not used in photovoltaic modules onto active cell areas.

  16. Social Effectiveness Therapy for Children: Five Years Later

    ERIC Educational Resources Information Center

    Beidel, Deborah C.; Turner, Samuel M.; Young, Brennan J.

    2006-01-01

    Social Effectiveness Therapy for Children (SET-C) is a comprehensive behavioral treatment combining social skills training, peer generalization experiences, and individualized in vivo exposure for the treatment of social phobia in youth. SET-C results in positive treatment outcome and its effects are maintained at least 3 years later. In this…

  17. Effects of lateral osteotomy on surgically assisted rapid maxillary expansion.

    PubMed

    Oliveira, T F M; Pereira-Filho, V A; Gabrielli, M A C; Gonçales, E S; Santos-Pinto, A

    2016-04-01

    This study aimed to assess the potential effects of two different osteotomy designs of the maxillary lateral wall on dental and skeletal changes after surgically assisted rapid maxillary expansion (SARME). Thirty adult patients were divided into two groups according to the lateral osteotomy design: group 1 (n=16) underwent lateral osteotomy performed in a horizontal straight fashion, and group 2 (n=14) underwent lateral osteotomy performed in parallel to the occlusal plane with a step at the zygomatic buttress. Cone beam computed tomography scans were obtained preoperatively (T1), immediately after expansion (T2), and 6 months after expansion (T3). Mixed analysis of variance (ANOVA) was used for the statistical analysis. The results showed no significant interaction effect between groups and time points. Therefore, maxillary expansion was effective in both groups. Statistically significant increases in all dental and skeletal measurements were observed immediately after expansion (P<0.001). Relapse of the nasal floor width, tipping of the supporting teeth, and an increase in root distance in molars occurred at T3 (P<0.05). In summary, the maxillary lateral osteotomy design did not influence the results of SARME, which occurred mainly through the inclination of maxillary segments. PMID:26688294

  18. Nanoscale optimization of quantum dot media for effective photovoltaic conversion

    NASA Astrophysics Data System (ADS)

    Sablon, K. A.; Sergeev, A.; Little, J. W.; Vagidov, N.; Mitin, V.

    2014-06-01

    Nanoscale engineering of band profile and potential profile provide effective tools for the management of photoelectron processes in quantum dot (QD) photovoltaic devices. We investigate the QD devices with various 1-μm InAs /GaAs QD media placed in a 3-μm base GaAs p-n junction. We found that n-charging of quantum dots (QDs) create potential barriers around QDs. QD growth between ultrathin AlGaAs layers leads to the formation of AlGaAs "fence" barriers, and reduces the wetting layers (WLs). The barriers around QDs and reduction of the wetting layer substantially suppress recombination processes via QDs. The n-doping of interdot space in QD media enhances electron extraction from QDs. All of our QD devices show short-circuit current, JSC, higher than that of the reference cell, but smaller open-circuit voltage, VOC.. In the QD devices, the short circuit currents increase by ~0.1 mA/cm2 per dot layer. JSC reaches 28.4 mA/cm2 in the device with QD media that combines dot charging, fence barriers, and WL reduction.

  19. Pilot opinions of sampling effects in lateral-directional control

    NASA Technical Reports Server (NTRS)

    Stengel, R. F.; Miller, G. E.

    1982-01-01

    Flight experiments with a microprocessor control system were conducted to determine the effects of variations in sampling parameters on several pilots' opinions of lateral-directional flying qualities. Princeton's variable-response research aircraft (VRA), which is equipped with a microprocessor based digital flight control system (Micro-DFCS), was the test vehicle. Two U.S. Navy pilots evaluated the effects of sampling rate, quantization, and pure time delay during tracking, approach, and landing. Aircraft carrier approach tasks were conducted using a Navy approach mirror. Acquisition and tracking of fixed objects on the ground provided additional information related to the Navy misson. The longitudinal controls were implemented with analog electronics, while the lateral-directional pilot inputs (stick and rudder) were fed to the Micro-DFCS, which commanded the ailerons and rudder. The conceptual relationship between the evaluation pilot's lateral-directional inputs, the flight computer, and the aircraft are illustrated.

  20. Effect of a Stress Management Class: One Year Later.

    ERIC Educational Resources Information Center

    Somerville, Addison W.; And Others

    1984-01-01

    Graduate and undergraduate students showed a reduction in anxiety during a 16-week course designed to include information on the causes and effects of stress as well as practical techniques for stress management. A follow-up study showed that the students were still successfully using the stress management techniques a year later. (RM)

  1. Lateral vibration effects in atomic-scale friction

    SciTech Connect

    Roth, R.; Fajardo, O. Y.; Mazo, J. J.; Meyer, E.; Gnecco, E.

    2014-02-24

    The influence of lateral vibrations on the stick-slip motion of a nanotip elastically pulled on a flat crystal surface is studied by atomic force microscopy measurements on a NaCl(001) surface in ultra-high vacuum. The slippage of the nanotip across the crystal lattice is anticipated at increasing driving amplitude, similarly to what is observed in presence of normal vibrations. This lowers the average friction force, as explained by the Prandtl-Tomlinson model with lateral vibrations superimposed at finite temperature. Nevertheless, the peak values of the lateral force, and the total energy losses, are expected to increase with the excitation amplitude, which may limit the practical relevance of this effect.

  2. Photovoltaic effect for narrow-gap Mott insulators

    NASA Astrophysics Data System (ADS)

    Manousakis, Efstratios

    2012-02-01

    Solar cells, based on conventional band-semiconductors, have low efficiency for conversion of solar into electrical energy. The main reason is that the excess energy of the photon absorbed by an electron/hole pair beyond the band-gap becomes heat through electron-phonon scattering and phonon emission; through these processes electrons and holes relax to their band edges within a characteristic time scale of the order of 10-12-10-13 secs. We will discuss that a narrow-gap Mott insulator can produce a significant photovoltaic effect and, more importantly, if appropriately chosen it can lead to solar cells of high efficiency. In this case, a single solar photon can produce multiple electron/hole (doublon/hole) pairs, an effect known as impact ionization, faster than other relaxation processes such as relaxation through phonons. It has been proposed previously that this process could lead to an efficient solar cell using band-gap semiconductors; however, the characteristic time-scale for impact ionization is comparable to that for electron-phonon relaxation in band-gap semiconductors. The reason that a Mott insulator can behave differently is that the large Coulomb repulsion present in a Mott insulator leads to a large enhancement of the impact ionization rate. Provided that this enhancement does occur in an appropriately chosen Mott insulator, it can be demonstrated that the efficiency can improve significantly over conventional band-insulators. At present, we are doing calculations on specific transition-metal-oxide based materials believed to be Mott-insulators using extensions of the density functional theory (hybrid functionals) in combination with many-body perturbation theory. Our goal is to determine a promising candidate with suitable band structure and transition matrix elements leading to fast transition rates for impact ionization to occur in a time-scale faster than other relaxation processes.

  3. Effect of Component Failures on Economics of Distributed Photovoltaic Systems

    SciTech Connect

    Lubin, Barry T.

    2012-02-02

    This report describes an applied research program to assess the realistic costs of grid connected photovoltaic (PV) installations. A Board of Advisors was assembled that included management from the regional electric power utilities, as well as other participants from companies that work in the electric power industry. Although the program started with the intention of addressing effective load carrying capacity (ELCC) for utility-owned photovoltaic installations, results from the literature study and recommendations from the Board of Advisors led investigators to the conclusion that obtaining effective data for this analysis would be difficult, if not impossible. The effort was then re-focused on assessing the realistic costs and economic valuations of grid-connected PV installations. The 17 kW PV installation on the University of Hartford's Lincoln Theater was used as one source of actual data. The change in objective required a more technically oriented group. The re-organized working group (changes made due to the need for more technically oriented participants) made site visits to medium-sized PV installations in Connecticut with the objective of developing sources of operating histories. An extensive literature review helped to focus efforts in several technical and economic subjects. The objective of determining the consequences of component failures on both generation and economic returns required three analyses. The first was a Monte-Carlo-based simulation model for failure occurrences and the resulting downtime. Published failure data, though limited, was used to verify the results. A second model was developed to predict the reduction in or loss of electrical generation related to the downtime due to these failures. Finally, a comprehensive economic analysis, including these failures, was developed to determine realistic net present values of installed PV arrays. Two types of societal benefits were explored, with quantitative valuations developed for

  4. A Photoferroelectric Perovskite-Type Organometallic Halide with Exceptional Anisotropy of Bulk Photovoltaic Effects.

    PubMed

    Sun, Zhihua; Liu, Xitao; Khan, Tariq; Ji, Chengmin; Asghar, Muhammad Adnan; Zhao, Sangen; Li, Lina; Hong, Maochun; Luo, Junhua

    2016-05-23

    Perovskite-type ferroelectrics composed of organometallic halides are emerging as a promising alternative to conventional photovoltaic devices because of their unique photovoltaic effects (PVEs). A new layered perovskite-type photoferroelectric, bis(cyclohexylaminium) tetrabromo lead (1), is presented. The material exhibits an exceptional anisotropy of bulk PVEs. Upon photoexcitation, superior photovoltaic behaviors are created along its inorganic layers, which are composed of corner-sharing PbBr6 octahedra. Semiconducting activity with remarkable photoconductivity is achieved in the vertical direction, showing sizeable on/off current ratios (>10(4) ), which compete with the most active photovoltaic material CH3 NH3 PbI3 . In 1 the temperature-dependence of photovoltage coincides fairly well with that of polarization, confirming the dominant role of ferroelectricity in such highly anisotropic PVEs. This finding sheds light on bulk PVEs in ferroelectric materials, and promotes their application in optoelectronic devices. PMID:27088882

  5. Organic photovoltaics: potential fate and effects in the environment.

    PubMed

    Zimmermann, Yannick-Serge; Schäffer, Andreas; Hugi, Christoph; Fent, Karl; Corvini, Philippe F-X; Lenz, Markus

    2012-11-15

    In times of dwindling fossil fuels it is particularly crucial to develop novel "green" technologies in order to cover the increasing worldwide demand for energy. Organic photovoltaic solar cells (OPVs) are promising as a renewable energy source due to low energy requirement for production, low resource extraction, and no emission of greenhouse gasses during use. In contrast to silicium-based solar cells, OPVs offer the advantages of light-weight, semi-transparency and mechanical flexibility. As to a possible forthcoming large-scale production, the environmental impact of such OPVs should be assessed and compared to currently best available technologies. For the first time, this review compiles the existing knowledge and identifies gaps regarding the environmental impact of such OPVs in a systematic manner. In this regard, we discuss the components of a typical OPV layer by layer. We discuss the probability of enhanced release of OPV-borne components into the environment during use-phase (e.g. UV- and biodegradation) and end-of-life phase (e.g. incineration and waste disposal). For this purpose, we compiled available data on bioavailability, bioaccumulation, biodegradation, and ecotoxicity. Whereas considerable research has already been carried out concerning the ecotoxicity of certain OPV components (e.g. nanoparticles and fullerenes), others have not been investigated at all so far. In conclusion, there is a general lack of information about fate, behavior as well as potential ecotoxicity of most of the main OPV components and their degradation/transformation products. So far, there is no evidence for a worrying threat coming from OPVs, but since at present, no policy and procedures regarding recycling of OPVs are in action, in particular improper disposal upon end-of-life might result in an adverse effect of OPVs in the environment when applied in large-scale. PMID:23022661

  6. Effects of Solar Photovoltaic Panels on Roof Heat Transfer

    NASA Technical Reports Server (NTRS)

    Dominguez, A.; Klessl, J.; Samady, M.; Luvall, J. C.

    2010-01-01

    Building Heating, Ventilation and Air Conditioning (HVAC) is a major contributor to urban energy use. In single story buildings with large surface area such as warehouses most of the heat enters through the roof. A rooftop modification that has not been examined experimentally is solar photovoltaic (PV) arrays. In California alone, several GW in residential and commercial rooftop PV are approved or in the planning stages. With the PV solar conversion efficiency ranging from 5-20% and a typical installed PV solar reflectance of 16-27%, 53-79% of the solar energy heats the panel. Most of this heat is then either transferred to the atmosphere or the building underneath. Consequently solar PV has indirect effects on roof heat transfer. The effect of rooftop PV systems on the building roof and indoor energy balance as well as their economic impacts on building HVAC costs have not been investigated. Roof calculator models currently do not account for rooftop modifications such as PV arrays. In this study, we report extensive measurements of a building containing a flush mount and a tilted solar PV array as well as exposed reference roof. Exterior air and surface temperature, wind speed, and solar radiation were measured and thermal infrared (TIR) images of the interior ceiling were taken. We found that in daytime the ceiling surface temperature under the PV arrays was significantly cooler than under the exposed roof. The maximum difference of 2.5 C was observed at around 1800h, close to typical time of peak energy demand. Conversely at night, the ceiling temperature under the PV arrays was warmer, especially for the array mounted flat onto the roof. A one dimensional conductive heat flux model was used to calculate the temperature profile through the roof. The heat flux into the bottom layer was used as an estimate of the heat flux into the building. The mean daytime heat flux (1200-2000 PST) under the exposed roof in the model was 14.0 Watts per square meter larger than

  7. Effect of molecular electrical doping on polyfuran based photovoltaic cells

    SciTech Connect

    Yu, Shuwen; Opitz, Andreas; Salzmann, Ingo; Frisch, Johannes; Cohen, Erez; Bendikov, Michael; Koch, Norbert

    2015-05-18

    The electronic, optical, and morphological properties of molecularly p-doped polyfuran (PF) films were investigated over a wide range of doping ratio in order to explore the impact of doping in photovoltaic applications. We find evidence for integer-charge transfer between PF and the prototypical molecular p-dopant tetrafluoro-tetracyanoquinodimethane (F4TCNQ) and employed the doped polymer in bilayer organic solar cells using fullerene as acceptor. The conductivity increase in the PF films at dopant loadings ≤2% significantly enhances the short-circuit current of photovoltaic devices. For higher doping ratios, however, F4TCNQ is found to precipitate at the heterojunction between the doped donor polymer and the fullerene acceptor. Ultraviolet photoelectron spectroscopy reveals that its presence acts beneficial to the energy-level alignment by doubling the open-circuit voltage of solar cells from 0.2 V to ca. 0.4 V, as compared to pristine PF.

  8. Study of the photovoltaic effect in thin film barium titanate

    NASA Technical Reports Server (NTRS)

    Grannemann, W. W.; Dharmadhikari, V. S.

    1982-01-01

    The basic mechanism associated with the photovoltaic phenomena observed in the R.F. sputtered BaTiO3/silicon system is presented. Series of measurements of short circuit photocurrents and open circuit photovoltage were made. The composition depth profiles and the interface characteristics of the BaTiO3/silicon system were investigated for a better understanding of the electronic properties. A Scanning Auger Microprobe combined with ion in depth profiling were used.

  9. Low earth orbit environmental effects on the Space Station photovoltaic power generation systems

    NASA Technical Reports Server (NTRS)

    Nahra, H. K.

    1988-01-01

    A summary of the low earth orbital environment, its impact on the photovoltaic power systems of the Space Station and the solutions implemented to resolve the environmental concerns or issues are described. Low earth orbital environment (LEO) presents several concerns to the photovoltaic power systems of the Space Station. These concerns include atomic oxygen interaction with the polymeric substrate of the solar arrays, ionized environment effects on the array operating voltage, the effects of the meteoroids and debris impacts and penetration through the different layers of the solar cells and their circuits, and the high energy particle and radiation effects on the overall solar array performance. Potential solutions to some of the degrading environmental interactions that will provide the photovoltaic power system of the Space Station with the desired life are also summarized.

  10. Low Earth orbit environmental effects on the space station photovoltaic power generation systems

    NASA Technical Reports Server (NTRS)

    Nahra, Henry K.

    1987-01-01

    A summary of the Low Earth Orbital Environment, its impact on the Photovoltaic Power systems of the space station and the solutions implemented to resolve the environmental concerns or issues are described. Low Earth Orbital Environment (LEO) presents several concerns to the Photovoltaic power systems of the space station. These concerns include atomic oxygen interaction with the polymeric substrate of the solar arrays, ionized environment effects on the array operating voltage, the effects of the meteoroids and debris impacts and penetration through the different layers of the solar cells and their circuits, and the high energy particle and radiation effects on the overall solar array performance. Potential solutions to some of the degrading environmental interactions that will provide the photovoltaic power system of the space station with the desired life are also summarized.

  11. [The influences of laterality on global precedence: interference effects].

    PubMed

    Kimura, Jun

    2008-02-01

    This study aimed to clarify the influence of laterality on interference effects for global precedence, and to examine the mechanism of these effects. In most previous studies, the neutral condition was excluded from the consistency factor and the difference of latencies between the consistent and inconsistent conditions was regarded as the interference score, which may not be accurate. In this study, the difference of latencies between the neutral and the inconsistent condition was regarded as the interference score. The results of the analysis of variance (ANOVA) for latencies showed that interference effects influenced only right visual field-left hemisphere (RVF-LH), and facilitation effects influenced only left visual field-right hemisphere (LVF-RH) in the local condition. These findings indicate that it does not matter how optimal processing influenced interference effects on suboptimal processing in each hemisphere, for example how global processing influenced local processing in the right hemisphere, but rather how each hemisphere controlled optimal processing. PMID:18402064

  12. THE EFFECTS OF BRAIN LATERALIZATION ON MOTOR CONTROL AND ADAPTATION

    PubMed Central

    Mutha, Pratik K.; Haaland, Kathleen Y.; Sainburg, Robert L.

    2012-01-01

    Lateralization of mechanisms mediating functions such as language and perception is widely accepted as a fundamental feature of neural organization. Recent research has revealed that a similar organization exists for the control of motor actions, in that each brain hemisphere contributes unique control mechanisms to the movements of each arm. We now review current research that addresses the nature of the control mechanisms that are lateralized to each hemisphere and how they impact motor adaptation and learning. In general, the studies reviewed here suggest an enhanced role for the left hemisphere during adaptation, and the learning of new sequences and skills. We suggest that this specialization emerges from a left hemisphere specialization for predictive control – the ability to effectively plan and coordinate motor actions, possibly by optimizing certain cost functions. In contrast, right hemisphere circuits appear to be important for updating ongoing actions and stopping at a goal position, through modulation of sensorimotor stabilization mechanisms such as reflexes. We also propose that each brain hemisphere contributes its mechanism to the control of both arms. We conclude by examining the potential advantages of such a lateralized control system. PMID:23237468

  13. Hemispace asymmetries and laterality effects in arm positioning.

    PubMed

    Imanaka, K; Abernethy, B; Yamauchi, M; Funase, K; Nishihira, Y

    1995-12-01

    Hemispace asymmetries and laterality effects were examined on an arm positioning reproduction task. Sixteen male subjects were asked to reproduce both abductive and adductive positioning movements with the left or right arm within either the left or the right hemispace. Hemispace was manipulated using a 90 degrees head-rotation paradigm. A left hemispace advantage in positioning accuracy was predicted for both left and right arm movements on the grounds that the perceptual-motor control of positioning movements made in left hemispace is primarily mediated by the right hemisphere which is known to be advantageous for tasks which are spatial in nature (Heilman, Bowers, & Watson, 1984). No arm laterality effects were predicted to occur because the proximal musculature involved in the control of arm movements is innervated from both contralateral and ipsilateral cerebral hemispheres (Brinkman & Kuypers, 1973). Results showed that the predicted left hemispace advantage was evident for the right arm on the positioning variability measure alone, whereas it was absent for all other possible conditions on all error measures. Laterality (arm) effects were absent as predicted. The experiment also demonstrated a greater degradation of reproduction performance under the "crossed" arm-hemispace conditions than under the "uncrossed" conditions. A plausible explanation for the uncrossed advantage for the task is that under normal conditions, a single hemisphere is primarily responsible for both controlling the contralateral arm and directing attention to the contralateral hemispace, and consequently potential interhemispheric interference is minimized. A clear response bias effect in movement reproduction was also evident as a function of the direction of concurrent arm movement and head rotation. Arm movements made in the same direction as head rotation were systematically undershot in reproduction to a much greater degree than arm movements made in the opposite direction to head

  14. Enhancement of the Bulk Photovoltaic Effect in Topological Insulators

    NASA Astrophysics Data System (ADS)

    Tan, Liang Z.; Rappe, Andrew M.

    2016-06-01

    We investigate the shift current bulk photovoltaic response of materials close to a band inversion topological phase transition. We find that the bulk photocurrent reverses direction across the band inversion transition, and that its magnitude is enhanced in the vicinity of the phase transition. These results are demonstrated with first principles density functional theory calculations of BiTeI and CsPbI3 under hydrostatic pressure, and explained with an analytical model, suggesting that this phenomenon remains robust across disparate material systems.

  15. Angle-dependent photovoltaic effect in Al-Si multilayers

    SciTech Connect

    Kyarad, A.; Lengfellner, H.

    2005-10-31

    Al-Si multilayer stacks have been prepared by an alloying process from aluminum and silicon platelets. Irradiation of a stack with infrared to visible laser radiation generates photovoltaic signals depending on the angle of incidence of the laser beam with respect to the layer planes, with zero signal and a polarity reversal for beam and layers in parallel. Results are explained in terms of photoactive layers connected in series and symmetrically aligned along the stack axis. For light beams inclined with respect to the layer planes, asymmetry is introduced by fractional shadowing of photoactive regions due to the intransparent metallic layers.

  16. Magnetic field effects in a polymer/fullerene blend photovoltaic cell

    NASA Astrophysics Data System (ADS)

    Jang, Hyuk-Jae; Basham, James I.; Gundlach, David J.; Richter, Curt A.

    Organic photovoltaic (OPV) systems based on blends of conjugated polymers and fullerene derivatives have shown great promise for low-cost and efficient photovoltaic applications. Recent findings suggest that a weak external magnetic field can disturb the spin configuration of excited states and subsequently change properties of OPV cells such as photocurrent. These changes are referred to as magnetic field effects (MFEs). In order to have a better understanding of the underlying mechanisms responsible for the MFEs in polymer/fullerene blend photovoltaic systems, we fabricated poly-3-hexylthiophene (P3HT):phenyl-C61-butyric acid methyl ester (PC61BM) cells and carried out photovoltaic device performance and impedance spectroscopy measurements with and without an externally applied magnetic field. A significant reduction in short circuit current (JSC) as well as open circuit voltage (VOC) was observed with an applied magnetic field of a 0.1 tesla compared to those measured without a magnetic field under the same intensity of illumination. Impedance spectroscopy data gives insights into the influence of an external magnetic field on charge generation and recombination near normal photovoltaic operating conditions.

  17. Heat treatment effects in Cu2S-CdS heterojunction photovoltaic cells

    NASA Technical Reports Server (NTRS)

    Fahrenbruch, A. L.; Bube, R. H.

    1974-01-01

    The dependence of the short-circuit current on photon energy, temperature, and the state of optical degradation (or enhancement) is determined in a study of the photovoltaic properties of Cu2S-CdS single-crystal heterojunctions. A coherent formulation is proposed for the relationship between enhancement and optical degradation and for their effects on the transport of a short-circuit photoexcited current and dark forward-bias current in a photovoltaic cell. Optical degradation in a Cu2S-CdS cell is shown to be identical to the optical degradation of lifetime in a homogeneous CdS:Cd:Cu crystal.

  18. Giant bulk photovoltaic effect in thin ferroelectric BaTiO3 films

    NASA Astrophysics Data System (ADS)

    Zenkevich, A.; Matveyev, Yu.; Maksimova, K.; Gaynutdinov, R.; Tolstikhina, A.; Fridkin, V.

    2014-10-01

    The voltage generated in a noncentrosymmetric crystal due to the bulk photovoltaic effect (BPE) can greatly exceed the energy gap, however, the light energy conversion efficiency is extremely low. Here we show that the BPE is remarkably enhanced in the case of thin films. The measurements of the BPE in heteroepitaxial single domain ferroelectric BaTiO3 thin films reveal the enhancement of both photoinduced electric field and conversion efficiencies of the BPE by more than 4 orders of magnitude. Besides the fundamental aspect, our results indicate the potential for the use of the BPE in photovoltaic applications.

  19. Emotion word recognition: discrete information effects first, continuous later?

    PubMed

    Briesemeister, Benny B; Kuchinke, Lars; Jacobs, Arthur M

    2014-05-20

    Manipulations of either discrete emotions (e.g. happiness) or affective dimensions (e.g. positivity) have a long tradition in emotion research, but interactive effects have never been studied, based on the assumption that the two underlying theories are incompatible. Recent theorizing suggests, however, that the human brain relies on two affective processing systems, one working on the basis of discrete emotion categories, and the other working along affective dimensions. Presenting participants with an orthogonal manipulation of happiness and positivity in a lexical decision task, the present study meant to test the appropriateness of this assumption in emotion word recognition. Behavioral and electroencephalographic data revealed independent effects for both variables, with happiness affecting the early visual N1 component, while positivity affected an N400-like component and the late positive complex. These results are interpreted as evidence for a sequential processing of affective information, with discrete emotions being the basis for later dimensional appraisal processes. PMID:24713350

  20. Effects of windblown dust on photovoltaic surface s on Mars

    NASA Technical Reports Server (NTRS)

    Gaier, James R.; Perez-Davis, Marla E.; Moinuddin, Alia M.

    1991-01-01

    Photovoltaic (PV) coverslip material was subjected to Maritan dust storm conditions using basaltic dust flowing through the Martian Surface Wind Tunnel at NASA-Ames. Initially dusted and clear coverslips were held at angles from 0 to 90 deg., and the dust laden wind velocity was varied from 20 to 97 m/s. Blowing dust was found to adhere more to the coverslips as the angle was increased. However, dust was partially cleared from surfaces that were initially dusted at substantially lower velocities in dust laden wind than in clear wind. Thus, an equilibrium amount of dust accumulated which was dependent only upon angle and wind velocity and not upon initial concentration of dust. Abrasion was also evident in the coverslips. It increased with wind velocity and angle of attack. It appears that an initial dust layer may help to protect PV surfaces from abrasion.

  1. Shadow Effect on Photovoltaic Potentiality Analysis Using 3d City Models

    NASA Astrophysics Data System (ADS)

    Alam, N.; Coors, V.; Zlatanova, S.; Oosterom, P. J. M.

    2012-07-01

    Due to global warming, green-house effect and various other drawbacks of existing energy sources, renewable energy like Photovoltaic system is being popular for energy production. The result of photovoltaic potentiality analysis depends on data quality and parameters. Shadow rapidly decreases performance of the Photovoltaic system and it always changes due to the movement of the sun. Solar radiation incident on earth's atmosphere is relatively constant but the radiation at earth's surface varies due to absorption, scattering, reflection, change in spectral content, diffuse component, water vapor, clouds and pollution etc. In this research, it is being investigated that how efficiently real-time shadow can be detected for both direct and diffuse radiation considering reflection and other factors in contrast with the existing shadow detection methods using latest technologies and what is the minimum quality of data required for this purpose. Of course, geometric details of the building geometry and surroundings directly affect the calculation of shadows. In principle, 3D city models or point clouds, which contain roof structure, vegetation, thematically differentiated surface and texture, are suitable to simulate exact real-time shadow. This research would develop an automated procedure to measure exact shadow effect from the 3D city models and a long-term simulation model to determine the produced energy from the photovoltaic system. In this paper, a developed method for detecting shadow for direct radiation has been discussed with its result using a 3D city model to perform a solar energy potentiality analysis.

  2. Effect of single walled carbon nanotubes on the threshold voltage of dye based photovoltaic devices

    NASA Astrophysics Data System (ADS)

    Chakraborty, S.; Manik, N. B.

    2016-01-01

    Carbon nanotubes are being widely used in organic photovoltaic (OPV) devices as their usage has been reported to enhance the device efficiency along with other related parameters. In this work we have studied the energy (Ec) effect of single walled carbon nanotubes (SWCNT) on the threshold voltage (Vth) and also on the trap states of dye based photovoltaic devices. SWCNT is added in a series of dyes such as Rose Bengal (RB), Methyl Red (MR), Malachite Green (MG) and Crystal Violet (CV). By analysing the steady state dark current-voltage (I-V) characteristics Vth and Ec is estimated for the different devices with and without addition of SWCNT. It is observed that on an average for all the dyes Vth is reduced by about 30% in presence of SWCNT. The trap energy Ec also reduces in case of all the dyes. The relation between Vth, Ec and total trap density is discussed. From the photovoltaic measurements it is seen that the different photovoltaic parameters change with addition of SWCNT to the dye based devices. Both the short circuit current density and fill factor are found to increase for all the dye based devices in presence of SWCNT.

  3. Valence-Specific Laterality Effects in Vocal Emotion: Interactions with Stimulus Type, Blocking and Sex

    ERIC Educational Resources Information Center

    Schepman, Astrid; Rodway, Paul; Geddes, Pauline

    2012-01-01

    Valence-specific laterality effects have been frequently obtained in facial emotion perception but not in vocal emotion perception. We report a dichotic listening study further examining whether valence-specific laterality effects generalise to vocal emotions. Based on previous literature, we tested whether valence-specific laterality effects were…

  4. Role of domain walls in the abnormal photovoltaic effect in BiFeO3

    PubMed Central

    Bhatnagar, Akash; Roy Chaudhuri, Ayan; Heon Kim, Young; Hesse, Dietrich; Alexe, Marin

    2013-01-01

    Recently, the anomalous photovoltaic (PV) effect in BiFeO3 (BFO) thin films, which resulted in open circuit voltages (Voc) considerably larger than the band gap of the material, has generated a revival of the entire field of photoferroelectrics. Here, via temperature-dependent PV studies, we prove that the bulk photovoltaic (BPV) effect, which has been studied in the past for many non-centrosymmetric materials, is at the origin of the anomalous PV effect in BFO films. Moreover, we show that irrespective of the measurement geometry, Voc as high as 50 V can be achieved by controlling the conductivity of domain walls (DW). We also show that photoconductivity of the DW is markedly higher than in the bulk of BFO.

  5. Photovoltaic and photothermoelectric effect in a double-gated WSe2 device.

    PubMed

    Groenendijk, Dirk J; Buscema, Michele; Steele, Gary A; Michaelis de Vasconcellos, Steffen; Bratschitsch, Rudolf; van der Zant, Herre S J; Castellanos-Gomez, Andres

    2014-10-01

    Tungsten diselenide (WSe2), a semiconducting transition metal dichalcogenide (TMDC), shows great potential as active material in optoelectronic devices due to its ambipolarity and direct bandgap in its single-layer form. Recently, different groups have exploited the ambipolarity of WSe2 to realize electrically tunable PN junctions, demonstrating its potential for digital electronics and solar cell applications. In this Letter, we focus on the different photocurrent generation mechanisms in a double-gated WSe2 device by measuring the photocurrent (and photovoltage) as the local gate voltages are varied independently in combination with above- and below-bandgap illumination. This enables us to distinguish between two main photocurrent generation mechanisms, the photovoltaic and photothermoelectric effect. We find that the dominant mechanism depends on the defined gate configuration. In the PN and NP configurations, photocurrent is mainly generated by the photovoltaic effect and the device displays a maximum responsivity of 0.70 mA/W at 532 nm illumination and rise and fall times close to 10 ms. Photocurrent generated by the photothermoelectric effect emerges in the PP configuration and is a factor of 2 larger than the current generated by the photovoltaic effect (in PN and NP configurations). This demonstrates that the photothermoelectric effect can play a significant role in devices based on WSe2 where a region of strong optical absorption, caused by, for example, an asymmetry in flake thickness or optical absorption of the electrodes, generates a sizable thermal gradient upon illumination. PMID:25232893

  6. Temperature-Dependent Polarization in Field-Effect Transport and Photovoltaic Measurements of Methylammonium Lead Iodide.

    PubMed

    Labram, John G; Fabini, Douglas H; Perry, Erin E; Lehner, Anna J; Wang, Hengbin; Glaudell, Anne M; Wu, Guang; Evans, Hayden; Buck, David; Cotta, Robert; Echegoyen, Luis; Wudl, Fred; Seshadri, Ram; Chabinyc, Michael L

    2015-09-17

    While recent improvements in the reported peak power conversion efficiency (PCE) of hybrid organic-inorganic perovskite solar cells have been truly astonishing, there are many fundamental questions about the electronic behavior of these materials. Here we have studied a set of electronic devices employing methylammonium lead iodide ((MA)PbI3) as the active material and conducted a series of temperature-dependent measurements. Field-effect transistor, capacitor, and photovoltaic cell measurements all reveal behavior consistent with substantial and strongly temperature-dependent polarization susceptibility in (MA)PbI3 at temporal and spatial scales that significantly impact functional behavior. The relative PCE of (MA)PbI3 photovoltaic cells is observed to reduce drastically with decreasing temperature, suggesting that such polarization effects could be a prerequisite for high-performance device operation. PMID:26722725

  7. Switchable photovoltaic effect in bilayer graphene/BiFeO3/Pt heterostructures

    NASA Astrophysics Data System (ADS)

    Katiyar, Rajesh K.; Misra, Pankaj; Mendoza, Frank; Morell, Gerardo; Katiyar, Ram S.

    2014-10-01

    We report the switchable photovoltaic effects in graphene/BiFeO3/Pt heterostructures. Pure phase polycrystalline BiFeO3 films were deposited on Pt/TiO2/SiO2/Si substrates by pulse laser deposition. A bilayer graphene was transferred onto the BiFeO3 film which serves as transparent conducting electrodes. The heterostructures showed switchable photovoltaic effect depending on ferroelectric polarization directions indicating depolarization field induced separation of photo-generated carriers. The open circuit voltage (VOC) and short circuit current density (JSC) were measured to be ˜110 mV, ˜92 μA/cm2 in positive polarity and similar values were obtained when the polarity was reversed. The JSC and VOC also showed rapid response (<100 ms) as a function of light exposure time.

  8. Enhancement in photovoltaic properties of silicon solar cells by surface plasmon effect of palladium nanoparticles

    NASA Astrophysics Data System (ADS)

    Atyaoui, Malek; Atyaoui, Atef; Khalifa, Marwen; Elyagoubi, Jalel; Dimassi, Wissem; Ezzaouia, Hatem

    2016-04-01

    This work presents the surface Plasmon effect of Palladium nanoparticles (Pd NPs) on the photovoltaic properties of silicon solar cells. Pd NPs were deposited on the p-type silicon base of the n+/p junction using a chemical deposition method in an aqueous solution containing Palladium (II) Nitrate (PdNO3)2 and Ammonium Hydroxide (NH4OH) followed by a thermal treatment at 500 °C under nitrogen atmosphere. Chemical composition and surface morphology of the treated silicon base were examined by energy dispersive X-ray (EDX) spectroscopy, scanning electronic microscopy (SEM) and Atomic Force Microscopy (AFM). The effect of the deposited Pd NPs on the electrical properties was evaluated by the internal quantum efficiency (IQE) and current-voltage (I-V) measurements. The results indicate that the formation of the Pd NPs is accompanied by an enhanced light absorption and improved photovoltaic parameters.

  9. Facile Hydrothermal Preparation of ZNO/CO3O4 Heterogeneous Nanostructures and its Photovoltaic Effect

    NASA Astrophysics Data System (ADS)

    Wei, Fanan; Jiang, Minlin; Liu, Lianqing

    2015-07-01

    Photovoltaic technology offers great potential in the replacement of fossil fuel resources, but still suffers from high device fabrication cost. Herein, we attempted to provide a solution to these issues with heterogeneous nanostructures. Firstly, Zinc oxide (ZnO)/cobalt oxide (Co3O4) heterojunction nanowires are prepared through facile fabrication methods. By assembling Co(OH)2 nanoplates on ZnO nanowire arrays, the ZnO/Co3O4 heterogeneous nanostructures are uniformly synthesized on ITO coated glass and wafer. Current (I)-voltage (V) measurement through conductive atomic force microscope shows excellent photovoltaic effect. And, the heterojunction nanostructures shows unprecedented high open circuit voltage. Therefore, the potential application of the heterogeneous nanostructures in solar cells is demonstrated.

  10. Band alignment and photovoltaic effect of epitaxial α-PbO thin films

    NASA Astrophysics Data System (ADS)

    Majima, Eishi; Kozuka, Yusuke; Uchida, Masaki; Nakamura, Masao; Kawasaki, Masashi

    2015-07-01

    To explore a p-type semiconductor lattice-matched with perovskite transition-metal oxides, we have grown α-PbO(001) thin films on (Nb-doped) SrTiO3(001) and GdScO3(110) substrates by pulsed laser deposition. The photovoltaic effect in a Au/α-PbO/Nb:SrTiO3 heterojunction is enhanced compared with that in a Au/Nb:SrTiO3 Schottky junction. The band alignment is deduced from photocurrent action spectra. We conclude that α-PbO facilitates the separation of electron-hole pairs generated at the interface of the SrTiO3 side in the ultraviolet light region and of the α-PbO side in the visible light region. Our results indicate that α-PbO is a promising candidate for photovoltaic heterojunctions involving strongly correlated oxides.

  11. Assessing the Performance of the Photovoltaic Cells on the Effects of Yellow Dust Events and Haze in Seoul, Korea

    NASA Astrophysics Data System (ADS)

    Choi, Jiyeon; Kim, Yong Pyo; Wee, DaeHyun

    2016-04-01

    We analyze the potential effects of the Asian yellow dust Events and haze on the performance of Korean photovoltaic systems. Particulate matters from the Asian yellow dust outbreaks in the deserts of Mongolia and northern China are typically transported to Korea. Haze is an atmospheric phenomenon where dust, smoke and other dry particles obscure the clarity of the sky. Hence, we conjecture that the effects of the Asian yellow dust and haze block the incident solar irradiance. The potential reduction of the solar spectral irradiance due to Asian yellow dust events and haze in Korea is investigated using a clear-sky spectral radiation model, and the performance of photovoltaic systems under reduced irradiance is estimated by using a simple analytic model representing typical photovoltaic cells. Comparison of photovoltaic performance under Asian dust events, haze and that under a clear condition is made to evaluate overall influence of the particulate air pollution, respectively.

  12. Flexible, rollable photovoltaic cell module

    SciTech Connect

    Cull, C.R.; Hartman, R.A.; Koch, P.E.

    1986-03-04

    A photovoltaic module is described consisting of: busbar means; individual photovoltaic cell strips, each cell strip having an electrically conductive substrate layer, a semiconductor body deposited on the substrate layer, and a transparent electrically conductive layer deposited on the semiconductor body, the transparent electrically conductive layer being selectively sectioned to define electrically distinct photovoltaic cells carried by the cell strip; grid means deposited on the transparent electrically conductive layer of each of the photovoltaic cell; continuous electrically conductive filament means alternately and repetitively connected, at contact points, to the electrically conductive substrate layer of one photovoltaic cell strip and to the grid means of another photovoltaic cell strip; wherein the filament means is connected medially of the lateral edges of the respective cell strips; and means for connecting the transparent electrically conductive layer of one photovoltaic cell strip to the busbar means.

  13. Cerebral Laterality Effects in the Dual Processing of Prose.

    ERIC Educational Resources Information Center

    Dean, Raymond S.

    1984-01-01

    The degree to which concreteness of prose material presented in an auditory fashion would interact with learners' lateral preference under different right hemispheric presentation conditions was investigated with 96 adults. Subjects recalled a greater number of ideas when the passage was concrete. Abstractness interacted with cerebral dominance.…

  14. The Effects of Bilateral Presentations on Lateralized Lexical Decision

    ERIC Educational Resources Information Center

    Fernandino, Leonardo; Iacoboni, Marco; Zaidel, Eran

    2007-01-01

    We investigated how lateralized lexical decision is affected by the presence of distractors in the visual hemifield contralateral to the target. The study had three goals: first, to determine how the presence of a distractor (either a word or a pseudoword) affects visual field differences in the processing of the target; second, to identify the…

  15. Photovoltaic effect and charge storage in single ZnO nanowires

    SciTech Connect

    Liao Zhimin; Xu Jun; Zhang Jingmin; Yu Dapeng

    2008-07-14

    Asymmetric Schottky barriers between ZnO nanowire and metal electrode have been fabricated at the two ends of the nanowire. An obvious photocurrent generated from the device at zero voltage bias can be switched on/off with quick response by controlling the light irradiation. Moreover, the device can still afford a current at zero bias after switching off light illumination, which is ascribed to the charge storage effect in single ZnO nanowires. The underlying mechanisms related to the photovoltaic effect and charge storage were discussed.

  16. Measuring solar spectral and angle-of-incidence effects on photovoltaic modules and solar irradiance sensors

    SciTech Connect

    King, D.L.; Kratochvil, J.A.; Boyson, W.E.

    1997-11-01

    Historically, two time-of-day dependent factors have complicated the characterization of photovoltaic module and array performance; namely, changes in the solar spectrum over the day and optical effects in the module that vary with the solar angle-of-incidence. This paper describes straightforward methods for directly measuring the effects of these two factors. Measured results for commercial modules, as well as for typical solar irradiance sensors (pyranometers) are provided. The empirical relationships obtained from the measurements can be used to improve the methods used for system design, verification of performance after installation, and diagnostic monitoring of performance during operation.

  17. Study of the photovoltaic effect in thin film barium titanate

    NASA Technical Reports Server (NTRS)

    Grannemann, W. W.; Dharmadhikari, V. S.

    1981-01-01

    The photoelectric effect in structures consisting of metal deposited barium titanate film silicon is described. A radio frequency sputtering technique is used to deposit ferroelectric barium titantate films on silicon and quartz. Film properties are measured and correlated with the photoelectric effect characteristics of the films. It was found that to obtain good quality pin hole free films, it is necessary to reduce the substrate temperature during the last part of the deposition. The switching ability of the device with internal applied voltage is improved when applied with a ferroelectric memory device.

  18. Polarization-dependent interfacial coupling modulation of ferroelectric photovoltaic effect in PZT-ZnO heterostructures

    NASA Astrophysics Data System (ADS)

    Pan, Dan-Feng; Bi, Gui-Feng; Chen, Guang-Yi; Zhang, Hao; Liu, Jun-Ming; Wang, Guang-Hou; Wan, Jian-Guo

    2016-03-01

    Recently, ferroelectric perovskite oxides have drawn much attention due to potential applications in the field of solar energy conversion. However, the power conversion efficiency of ferroelectric photovoltaic effect currently reported is far below the expectable value. One of the crucial problems lies in the two back-to-back Schottky barriers, which are formed at the ferroelectric-electrode interfaces and blocking most of photo-generated carriers to reach the outside circuit. Herein, we develop a new approach to enhance the ferroelectric photovoltaic effect by introducing the polarization-dependent interfacial coupling effect. Through inserting a semiconductor ZnO layer with spontaneous polarization into the ferroelectric ITO/PZT/Au film, a p-n junction with strong polarization-dependent interfacial coupling effect is formed. The power conversion efficiency of the heterostructure is improved by nearly two orders of magnitude and the polarization modulation ratio is increased about four times. It is demonstrated that the polarization-dependent interfacial coupling effect can give rise to a great change in band structure of the heterostructure, not only producing an aligned internal electric field but also tuning both depletion layer width and potential barrier height at PZT-ZnO interface. This work provides an efficient way in developing highly efficient ferroelectric-based solar cells and novel optoelectronic memory devices.

  19. Polarization-dependent interfacial coupling modulation of ferroelectric photovoltaic effect in PZT-ZnO heterostructures

    PubMed Central

    Pan, Dan-Feng; Bi, Gui-Feng; Chen, Guang-Yi; Zhang, Hao; Liu, Jun-Ming; Wang, Guang-Hou; Wan, Jian-Guo

    2016-01-01

    Recently, ferroelectric perovskite oxides have drawn much attention due to potential applications in the field of solar energy conversion. However, the power conversion efficiency of ferroelectric photovoltaic effect currently reported is far below the expectable value. One of the crucial problems lies in the two back-to-back Schottky barriers, which are formed at the ferroelectric-electrode interfaces and blocking most of photo-generated carriers to reach the outside circuit. Herein, we develop a new approach to enhance the ferroelectric photovoltaic effect by introducing the polarization-dependent interfacial coupling effect. Through inserting a semiconductor ZnO layer with spontaneous polarization into the ferroelectric ITO/PZT/Au film, a p-n junction with strong polarization-dependent interfacial coupling effect is formed. The power conversion efficiency of the heterostructure is improved by nearly two orders of magnitude and the polarization modulation ratio is increased about four times. It is demonstrated that the polarization-dependent interfacial coupling effect can give rise to a great change in band structure of the heterostructure, not only producing an aligned internal electric field but also tuning both depletion layer width and potential barrier height at PZT-ZnO interface. This work provides an efficient way in developing highly efficient ferroelectric-based solar cells and novel optoelectronic memory devices. PMID:26954833

  20. Polarization-dependent interfacial coupling modulation of ferroelectric photovoltaic effect in PZT-ZnO heterostructures.

    PubMed

    Pan, Dan-Feng; Bi, Gui-Feng; Chen, Guang-Yi; Zhang, Hao; Liu, Jun-Ming; Wang, Guang-Hou; Wan, Jian-Guo

    2016-01-01

    Recently, ferroelectric perovskite oxides have drawn much attention due to potential applications in the field of solar energy conversion. However, the power conversion efficiency of ferroelectric photovoltaic effect currently reported is far below the expectable value. One of the crucial problems lies in the two back-to-back Schottky barriers, which are formed at the ferroelectric-electrode interfaces and blocking most of photo-generated carriers to reach the outside circuit. Herein, we develop a new approach to enhance the ferroelectric photovoltaic effect by introducing the polarization-dependent interfacial coupling effect. Through inserting a semiconductor ZnO layer with spontaneous polarization into the ferroelectric ITO/PZT/Au film, a p-n junction with strong polarization-dependent interfacial coupling effect is formed. The power conversion efficiency of the heterostructure is improved by nearly two orders of magnitude and the polarization modulation ratio is increased about four times. It is demonstrated that the polarization-dependent interfacial coupling effect can give rise to a great change in band structure of the heterostructure, not only producing an aligned internal electric field but also tuning both depletion layer width and potential barrier height at PZT-ZnO interface. This work provides an efficient way in developing highly efficient ferroelectric-based solar cells and novel optoelectronic memory devices. PMID:26954833

  1. Study of the photovoltaic effect in thin film barium titanate

    NASA Technical Reports Server (NTRS)

    Grannemann, W. W.; Dharmadhikari, V. S.

    1982-01-01

    Ferroelectric films of barium titanate were synthesized on silicon and quartz substrates, and the photoelectric effect in the structure consisting of metal deposited ferroelectric barium titanate film silicon was studied. A photovoltage with polarity that depends on the direction of the remanent polarization was observed. The deposition of BaTiO3 on silicon and fused quartz substrates was accomplished by an rf sputtering technique. A series of experiments to study the growth of ferroelectric BaTiO3 films on single crystal silicon and fused quartz substrates were conducted. The ferroelectric character in these films was found on the basis of evidence from the polarization electric field hysteresis loops, capacitance voltage and capacitance temperature techniques and from X-ray diffraction studies.

  2. Photovoltaic effect of light carrying orbital angular momentum on a semiconducting stripe.

    PubMed

    Wätzel, J; Moskalenko, A S; Berakdar, J

    2012-12-01

    We investigate the influence of a light beam carrying an orbital angular momentum on the current density of an electron wave packet in a semiconductor stripe. It is shown that due to the photo-induced torque the electron density can be deflected to one of the stripe sides. The direction of the deflection is controlled by the direction of the light orbital momentum. In addition the net current density can be enhanced. This is a photovoltaic effect that can be registered by measuring the generated voltage drop across the stripe and/or the current increase. PMID:23262724

  3. Update: Effective Load-Carrying Capability of Photovoltaics in the United States; Preprint

    SciTech Connect

    Perez, R.; Margolis, R.; Kmiecik, M.; Schwab, M.; Perez, M.

    2006-06-01

    This paper provides an update on the U.S. distribution of effective load-carrying capability (ELLC) for photovoltaics by analyzing recent load data from 39 U.S. utilities and time-coincident output of PV installations simulated from high-resolution, time/site-specific satellite data. Results show that overall regional trends identified in the early 1990s remain pertinent today, while noting a significant increase in PV ELCC in the western and northern United States, and a modest decrease in the central and eastern United States.

  4. Photogalvanic and photovoltaic effects in systems based on metal complexes of Schiff bases

    NASA Astrophysics Data System (ADS)

    Smirnova, E. A.; Besedina, M. A.; Karushev, M. P.; Vasil'ev, V. V.; Timonov, A. M.

    2016-05-01

    The nature of the processes that occur when electrodes modified with complexes [M(Schiff)] (M = Ni, Pd, Pt; Schiff denotes four-dentate Schiff base ligands) are irradiated with visible light for the potential use of these electrodes in photoelectrochemical energy conversion devices is considered. The factors responsible for shifts in the electrode potential upon photoexcitation, i.e., the nature of the metal site, the nature of the substituents in the sensitizer, and the oxygen concentration are discussed. Tentative mechanisms of the photovoltaic effects observed for conventional and semiconductor electrodes modified with [M(Schiff)] complexes are determined.

  5. Analysis of the harmonics and power-factor effects at a utility-intertied photovoltaic system

    SciTech Connect

    Campen, G.L.

    1982-01-01

    Outlined are the harmonics and power-factor characteristics and effects of a single residential photovoltaic (PV) installation using a line-commutated inverter. The data were taken during a five-day measurement program conducted at the John F. Long House, which is a prototype residential PV installation located in Phoenix, Arizona. The magnitude and phase of various currents and voltages from the fundamental to the 13th harmonic were recorded both with and without the operation of the PV system. A candidate method of modeling the installation for computer studies of larger concentrations is given.

  6. An analysis of the harmonics and power factor effects at a utility intertied photovoltaic system

    SciTech Connect

    Campen, G.L.

    1982-12-01

    This paper outlines the harmonics and power-factor characteristics and effects of a single residential photovoltaic (PV) installation using a line-commutated inverter. The data were taken during a five-day measurement program conducted at the John F. Long House, which is a prototype residential PV installation located in Phoenix, Arizona. The magnitude and phase of various currents and voltages from the fundamental to the 13th harmonic were recorded both with and without the operation of the PV system. A candidate method of modeling the installation for computer studies of larger concentrations is given.

  7. Effects of Immersion Solvent on Photovoltaic and Photophysical Properties of Porphyrin-Sensitized Solar Cells.

    PubMed

    Hayashi, Hironobu; Higashino, Tomohiro; Kinjo, Yuriko; Fujimori, Yamato; Kurotobi, Kei; Chabera, Pavel; Sundström, Villy; Isoda, Seiji; Imahori, Hiroshi

    2015-08-26

    Memory effects in self-assembled monolayers (SAMs) of zinc porphyrin carboxylic acid on TiO2 electrodes have been demonstrated for the first time by evaluating the photovoltaic and electron transfer properties of porphyrin-sensitized solar cells prepared by using different immersion solvents sequentially. The structure of the SAM of the porphyrin on the TiO2 was maintained even after treating the porphyrin monolayer with different neat immersion solvents (memory effect), whereas it was altered by treatment with solutions containing different porphyrins (inverse memory effect). Infrared spectroscopy shows that the porphyrins in the SAM on the TiO2 could be exchanged with the same or analogous porphyrin, leading to a change in the structure of the porphyrin SAM. The memory and inverse memory effects are well correlated with a change in porphyrin geometry, mainly the tilt angle of the porphyrin along the long molecular axis from the surface normal on the TiO2, as well as with kinetics of electron transfer between the porphyrin and TiO2. Such a new structure-function relationship for DSSCs will be very useful for the rational design and optimization of photoelectrochemical and photovoltaic properties of molecular assemblies on semiconductor surfaces. PMID:26266818

  8. Reliability of Laterality Effects in a Dichotic Listening Task with Words and Syllables

    ERIC Educational Resources Information Center

    Russell, Nancy L.; Voyer, Daniel

    2004-01-01

    Large and reliable laterality effects have been found using a dichotic target detection task in a recent experiment using word stimuli pronounced with an emotional component. The present study tested the hypothesis that the magnitude and reliability of the laterality effects would increase with the removal of the emotional component and variations…

  9. Organic photovoltaics

    NASA Astrophysics Data System (ADS)

    Leo, Karl

    2016-08-01

    Organic photovoltaics are on the verge of revolutionizing building-integrated photovoltaics. For other applications, however, several basic open scientific questions need answering to, in particular, further improve energy-conversion efficiency and lifetime.

  10. Origin of photovoltaic effect in superconducting YBa2Cu3O6.96 ceramics

    NASA Astrophysics Data System (ADS)

    Yang, F.; Han, M. Y.; Chang, F. G.

    2015-06-01

    We report remarkable photovoltaic effect in YBa2Cu3O6.96 (YBCO) ceramic between 50 and 300 K induced by blue-laser illumination, which is directly related to the superconductivity of YBCO and the YBCO-metallic electrode interface. There is a polarity reversal for the open circuit voltage Voc and short circuit current Isc when YBCO undergoes a transition from superconducting to resistive state. We show that there exists an electrical potential across the superconductor-normal metal interface, which provides the separation force for the photo-induced electron-hole pairs. This interface potential directs from YBCO to the metal electrode when YBCO is superconducting and switches to the opposite direction when YBCO becomes nonsuperconducting. The origin of the potential may be readily associated with the proximity effect at metal-superconductor interface when YBCO is superconducting and its value is estimated to be ~10-8 mV at 50 K with a laser intensity of 502 mW/cm2. Combination of a p-type material YBCO at normal state with an n-type material Ag-paste forms a quasi-pn junction which is responsible for the photovoltaic behavior of YBCO ceramics at high temperatures. Our findings may pave the way to new applications of photon-electronic devices and shed further light on the proximity effect at the superconductor-metal interface.

  11. Photovoltaic effect in few-layer black phosphorus PN junctions defined by local electrostatic gating

    NASA Astrophysics Data System (ADS)

    Buscema, Michele; Groenendijk, Dirk J.; Steele, Gary A.; van der Zant, Herre S. J.; Castellanos-Gomez, Andres

    2014-08-01

    In conventional photovoltaic solar cells, photogenerated carriers are extracted by the built-in electric field of a semiconductor PN junction, defined by ionic dopants. In atomically thin semiconductors, the doping level can be controlled by the field effect, enabling the implementation of electrically tunable PN junctions. However, most two-dimensional (2D) semiconductors do not show ambipolar transport, which is necessary to realize PN junctions. Few-layer black phosphorus (b-P) is a recently isolated 2D semiconductor with direct bandgap, high mobility, large current on/off ratios and ambipolar operation. Here we fabricate few-layer b-P field-effect transistors with split gates and hexagonal boron nitride dielectric. We demonstrate electrostatic control of the local charge carrier type and density in the device. Illuminating a gate-defined PN junction, we observe zero-bias photocurrents and significant open-circuit voltages due to the photovoltaic effect. The small bandgap of the material allows power generation for illumination wavelengths up to 940 nm, attractive for energy harvesting in the near-infrared.

  12. Photovoltaic effect in few-layer black phosphorus PN junctions defined by local electrostatic gating.

    PubMed

    Buscema, Michele; Groenendijk, Dirk J; Steele, Gary A; van der Zant, Herre S J; Castellanos-Gomez, Andres

    2014-01-01

    In conventional photovoltaic solar cells, photogenerated carriers are extracted by the built-in electric field of a semiconductor PN junction, defined by ionic dopants. In atomically thin semiconductors, the doping level can be controlled by the field effect, enabling the implementation of electrically tunable PN junctions. However, most two-dimensional (2D) semiconductors do not show ambipolar transport, which is necessary to realize PN junctions. Few-layer black phosphorus (b-P) is a recently isolated 2D semiconductor with direct bandgap, high mobility, large current on/off ratios and ambipolar operation. Here we fabricate few-layer b-P field-effect transistors with split gates and hexagonal boron nitride dielectric. We demonstrate electrostatic control of the local charge carrier type and density in the device. Illuminating a gate-defined PN junction, we observe zero-bias photocurrents and significant open-circuit voltages due to the photovoltaic effect. The small bandgap of the material allows power generation for illumination wavelengths up to 940 nm, attractive for energy harvesting in the near-infrared. PMID:25164986

  13. Origin of photovoltaic effect in superconducting YBa2Cu3O6.96 ceramics.

    PubMed

    Yang, F; Han, M Y; Chang, F G

    2015-01-01

    We report remarkable photovoltaic effect in YBa2Cu3O6.96 (YBCO) ceramic between 50 and 300 K induced by blue-laser illumination, which is directly related to the superconductivity of YBCO and the YBCO-metallic electrode interface. There is a polarity reversal for the open circuit voltage Voc and short circuit current Isc when YBCO undergoes a transition from superconducting to resistive state. We show that there exists an electrical potential across the superconductor-normal metal interface, which provides the separation force for the photo-induced electron-hole pairs. This interface potential directs from YBCO to the metal electrode when YBCO is superconducting and switches to the opposite direction when YBCO becomes nonsuperconducting. The origin of the potential may be readily associated with the proximity effect at metal-superconductor interface when YBCO is superconducting and its value is estimated to be ~10(-8) mV at 50 K with a laser intensity of 502 mW/cm(2). Combination of a p-type material YBCO at normal state with an n-type material Ag-paste forms a quasi-pn junction which is responsible for the photovoltaic behavior of YBCO ceramics at high temperatures. Our findings may pave the way to new applications of photon-electronic devices and shed further light on the proximity effect at the superconductor-metal interface. PMID:26099727

  14. Origin of photovoltaic effect in superconducting YBa2Cu3O6.96 ceramics

    PubMed Central

    Yang, F.; Han, M. Y.; Chang, F. G.

    2015-01-01

    We report remarkable photovoltaic effect in YBa2Cu3O6.96 (YBCO) ceramic between 50 and 300 K induced by blue-laser illumination, which is directly related to the superconductivity of YBCO and the YBCO-metallic electrode interface. There is a polarity reversal for the open circuit voltage Voc and short circuit current Isc when YBCO undergoes a transition from superconducting to resistive state. We show that there exists an electrical potential across the superconductor-normal metal interface, which provides the separation force for the photo-induced electron-hole pairs. This interface potential directs from YBCO to the metal electrode when YBCO is superconducting and switches to the opposite direction when YBCO becomes nonsuperconducting. The origin of the potential may be readily associated with the proximity effect at metal-superconductor interface when YBCO is superconducting and its value is estimated to be ~10–8 mV at 50 K with a laser intensity of 502 mW/cm2. Combination of a p-type material YBCO at normal state with an n-type material Ag-paste forms a quasi-pn junction which is responsible for the photovoltaic behavior of YBCO ceramics at high temperatures. Our findings may pave the way to new applications of photon-electronic devices and shed further light on the proximity effect at the superconductor-metal interface. PMID:26099727

  15. Gate-controlled terahertz single electron photovoltaic effect in self-assembled InAs quantum dots

    SciTech Connect

    Zhang, Y. Nagai, N.; Shibata, K.; Hirakawa, K.; Ndebeka-Bandou, C.; Bastard, G.

    2015-09-07

    We have observed a terahertz (THz) induced single electron photovoltaic effect in self-assembled InAs quantum dots (QDs). We used a single electron transistor (SET) geometry that consists of a single InAs QD and nanogap electrodes coupled with a bowtie antenna. Under a weak, broadband THz radiation, a photocurrent induced by THz intersublevel transitions in the QD is generated even when no bias voltage is applied to the SET. The observed single electron photovoltaic effect is due to an energy-dependent tunneling asymmetry in the QD-SET. Moreover, the tunneling asymmetry changes not only with the shell but also with the electron number in the QD, suggesting the manybody nature of the electron wavefunctions. The THz photovoltaic effect observed in the present QD-SET system may have potential applications to nanoscale energy harvesting.

  16. Gate-controlled terahertz single electron photovoltaic effect in self-assembled InAs quantum dots

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Shibata, K.; Nagai, N.; Ndebeka-Bandou, C.; Bastard, G.; Hirakawa, K.

    2015-09-01

    We have observed a terahertz (THz) induced single electron photovoltaic effect in self-assembled InAs quantum dots (QDs). We used a single electron transistor (SET) geometry that consists of a single InAs QD and nanogap electrodes coupled with a bowtie antenna. Under a weak, broadband THz radiation, a photocurrent induced by THz intersublevel transitions in the QD is generated even when no bias voltage is applied to the SET. The observed single electron photovoltaic effect is due to an energy-dependent tunneling asymmetry in the QD-SET. Moreover, the tunneling asymmetry changes not only with the shell but also with the electron number in the QD, suggesting the manybody nature of the electron wavefunctions. The THz photovoltaic effect observed in the present QD-SET system may have potential applications to nanoscale energy harvesting.

  17. Photovoltaic device

    DOEpatents

    Reese, Jason A.; Keenihan, James R.; Gaston, Ryan S.; Kauffmann, Keith L.; Langmaid, Joseph A.; Lopez, Leonardo C.; Maak, Kevin D.; Mills, Michael E.; Ramesh, Narayan; Teli, Samar R.

    2015-06-02

    The present invention is premised upon an improved photovoltaic device ("PV device"), more particularly to an improved photovoltaic device with a multilayered photovoltaic cell assembly and a body portion joined at an interface region and including an intermediate layer, at least one interconnecting structural member, relieving feature, unique component geometry, or any combination thereof.

  18. Photovoltaic device

    SciTech Connect

    Reese, Jason A.; Keenihan, James R.; Gaston, Ryan S.; Kauffmann, Keith L.; Langmaid, Joseph A.; Lopez, Leonardo C.; Maak, Kevin D.; Mills, Michael E.; Ramesh, Narayan; Teli, Samar R.

    2015-09-01

    The present invention is premised upon an improved photovoltaic device ("PV device"), more particularly to an improved photovoltaic device (10) with a multilayered photovoltaic cell assembly (100) and a body portion (200) joined at an interface region (410) and including an intermediate layer (500), at least one interconnecting structural member (1500), relieving feature (2500), unique component geometry, or any combination thereof.

  19. HIGH CHARGE EFFECTS IN SILICON DRIFT DETECTORS WITH LATERAL CONFINEMENT OF ELECTRONS.

    SciTech Connect

    CASTOLDI,A.; REHAK,P.

    1995-10-21

    A new drift detector prototype which provides suppression of the lateral diffusion of electrons has been tested as a function of the signal charge up to high charge levels, when electrostatic repulsion is not negligible. The lateral diffusion of the electron cloud has been measured for injected charges up to 2 {center_dot} 10{sup 5} electrons. The maximum number of electrons for which the suppression of the lateral spread is effective is obtained.

  20. A Test for Lateralization of the Mozart Effect.

    ERIC Educational Resources Information Center

    Bates, Angela; Cagle, Stacy; Rideout, Bruce

    The Mozart effect involves the enhancement of spatial processing after listening to a Mozart piano sonata (Rauscher, Dhaw, and Ky, 1993). Efforts to replicate the Mozart effect have been mixed, possibly due to differences in dependent variable operationalization across studies or large individual differences in magnitude of effect. Chabria and…

  1. Production of thin-film photovoltaic cells: health and environmental effects

    SciTech Connect

    Fthenakis, V.M.; Moskowitz, P.D.

    1985-10-01

    Health and safety hazards in production of major thin-film photovoltaic cells are identified and characterized for their potential to cause health effects. These hazards are identified by examining process data, control technology availability, biomedical effects, and environmental standards. Quantitative estimates of material inputs and outputs and control costs were made on the basis of preliminary engineering designs of hypothetical facilities capable of manufacturing 10 MWp photovoltaic cells a year. The most significant potential hazards are associated with toxic and explosive gases. Emissions of toxic gases during normal operation can be controlled using available control technology. Accidental release of stored gases, however, will pose significant risks to both workers and the public, as atmospheric dispersion computer studies indicate. Possible release preventing options and release control options are examined. Explosive and flammable gases may present significant occupational safety hazards; gas handling systems will need to be carefully designed. High voltages and radio frequency equipment also require close attention for their potential to present occupational hazards. 10 refs., 2 figs., 5 tabs.

  2. Cytoskeletal abnormalities in amyotrophic lateral sclerosis: beneficial or detrimental effects?

    PubMed

    Julien, J P; Beaulieu, J M

    2000-11-01

    Cytoskeletal abnormalities have been reported in cases of amyotrophic lateral sclerosis (ALS) including abnormal inclusions containing neurofilaments (NFs) and/or peripherin, reduced mRNA levels for the NF light (NF-L) protein and mutations in the NF heavy (NF-H) gene. Recently, transgenic mouse approaches have been used to address whether cytoskeletal changes may contribute to motor neuron disease. Mice lacking one of the three NF subunits are viable and do not develop motor neuron disease. Nonetheless, mice with null mutations for NF-L or for both NF-M and NF-H genes developed severe atrophy of ventral and dorsal root axons. The atrophic process is associated with hind limb paralysis during aging in mice deficient for both NF-M and NF-H proteins. The overexpression in mice of transgenes coding for wild-type or mutant NF proteins can provoke abnormal NF accumulations, axonal atrophy and sometimes motor dysfunction. However, the perikaryal NF accumulations are generally well tolerated by motor neurons and, except for expression of a mutant NF-L transgene, they did not provoke massive motor neuron death. Increasing the levels of perikaryal NF proteins may even confer protection in motor neuron disease caused by ALS-linked mutations in the superoxide dismutase (SOD1). In contrast, the overexpression of wild-type peripherin, a type of IF gene upregulated by inflammatory cytokines, provoked the formation of toxic IF inclusions with the high-molecular-weight NF proteins resulting in the death of motor neurons during aging. These results together with the detection of peripherin inclusions at early stage of disease in mice expressing mutant SOD1 suggest that IF inclusions containing peripherin may play a contributory role in ALS pathogenesis. PMID:11090858

  3. Performance optimization of dense-array concentrator photovoltaic system considering effects of circumsolar radiation and slope error.

    PubMed

    Wong, Chee-Woon; Chong, Kok-Keong; Tan, Ming-Hui

    2015-07-27

    This paper presents an approach to optimize the electrical performance of dense-array concentrator photovoltaic system comprised of non-imaging dish concentrator by considering the circumsolar radiation and slope error effects. Based on the simulated flux distribution, a systematic methodology to optimize the layout configuration of solar cells interconnection circuit in dense array concentrator photovoltaic module has been proposed by minimizing the current mismatch caused by non-uniformity of concentrated sunlight. An optimized layout of interconnection solar cells circuit with minimum electrical power loss of 6.5% can be achieved by minimizing the effects of both circumsolar radiation and slope error. PMID:26367685

  4. Communication Effectiveness of Individuals with Amyotrophic Lateral Sclerosis

    ERIC Educational Resources Information Center

    Ball, Laura J.; Beukelman, David R.; Pattee, Gary L.

    2004-01-01

    The purpose of this study was to examine the relationships among speech intelligibility and communication effectiveness as rated by speakers and their listeners. Participants completed procedures to measure (a) speech intelligibility, (b) self-perceptions of communication effectiveness, and (c) listener (spouse or family member) perceptions of…

  5. Sex Specific Effect of Prenatal Testosterone on Language Lateralization in Children

    ERIC Educational Resources Information Center

    Lust, J. M.; Geuze, R. H.; Van de Beek, C.; Cohen-Kettenis, P. T.; Groothuis, A. G. G.; Bouma, A.

    2010-01-01

    Brain lateralization refers to the division of labour between the two hemispheres in controlling a wide array of functions and is remarkably well developed in humans. Based on sex differences in lateralization of handedness and language, several hypotheses have postulated an effect of prenatal exposure to testosterone on human lateralization…

  6. Nanostructured photovoltaics

    NASA Astrophysics Data System (ADS)

    Fu, Lan; Tan, H. Hoe; Jagadish, Chennupati

    2013-01-01

    Energy and the environment are two of the most important global issues that we currently face. The development of clean and sustainable energy resources is essential to reduce greenhouse gas emission and meet our ever-increasing demand for energy. Over the last decade photovoltaics, as one of the leading technologies to meet these challenges, has seen a continuous increase in research, development and investment. Meanwhile, nanotechnology, which is considered to be the technology of the future, is gradually revolutionizing our everyday life through adaptation and incorporation into many traditional technologies, particularly energy-related technologies, such as photovoltaics. While the record for the highest efficiency is firmly held by multijunction III-V solar cells, there has never been a shortage of new research effort put into improving the efficiencies of all types of solar cells and making them more cost effective. In particular, there have been extensive and exciting developments in employing nanostructures; features with different low dimensionalities, such as quantum wells, nanowires, nanotubes, nanoparticles and quantum dots, have been incorporated into existing photovoltaic technologies to enhance their performance and/or reduce their cost. Investigations into light trapping using plasmonic nanostructures to effectively increase light absorption in various solar cells are also being rigorously pursued. In addition, nanotechnology provides researchers with great opportunities to explore the new ideas and physics offered by nanostructures to implement advanced solar cell concepts such as hot carrier, multi-exciton and intermediate band solar cells. This special issue of Journal of Physics D: Applied Physics contains selected papers on nanostructured photovoltaics written by researchers in their respective fields of expertise. These papers capture the current excitement, as well as addressing some open questions in the field, covering topics including the

  7. Polarity correspondence effect between loudness and lateralized response set

    PubMed Central

    Chang, Seah; Cho, Yang Seok

    2015-01-01

    Performance is better when a high pitch tone is associated with an up or right response and a low pitch tone with a down or left response compared to the opposite pairs, which is called the spatial-musical association of response codes effect. The current study examined whether polarity codes are formed in terms of the variation in loudness. In Experiments 1 and 2, in which participants performed a loudness-judgment task and a timbre-judgment task respectively, the correspondence effect was obtained between loudness and response side regardless of whether loudness was relevant to the task or not. In Experiments 3 and 4, in which the identical loudness- and timbre-judgment tasks were conducted while the auditory stimulus was presented only to the left or right ear, the correspondence effect was modulated by the ear to which the stimulus was presented, even though the effect was marginally significant in Experiment 4. The results suggest that loudness produced polarity codes that influenced response selection (Experiments 1 and 2), and additional spatial codes provided by stimulus position modulated the effect, generating the stimulus eccentricity effect (Experiments 3 and 4), which is consistent with the polarity correspondence principle. PMID:26052305

  8. Polarity correspondence effect between loudness and lateralized response set.

    PubMed

    Chang, Seah; Cho, Yang Seok

    2015-01-01

    Performance is better when a high pitch tone is associated with an up or right response and a low pitch tone with a down or left response compared to the opposite pairs, which is called the spatial-musical association of response codes effect. The current study examined whether polarity codes are formed in terms of the variation in loudness. In Experiments 1 and 2, in which participants performed a loudness-judgment task and a timbre-judgment task respectively, the correspondence effect was obtained between loudness and response side regardless of whether loudness was relevant to the task or not. In Experiments 3 and 4, in which the identical loudness- and timbre-judgment tasks were conducted while the auditory stimulus was presented only to the left or right ear, the correspondence effect was modulated by the ear to which the stimulus was presented, even though the effect was marginally significant in Experiment 4. The results suggest that loudness produced polarity codes that influenced response selection (Experiments 1 and 2), and additional spatial codes provided by stimulus position modulated the effect, generating the stimulus eccentricity effect (Experiments 3 and 4), which is consistent with the polarity correspondence principle. PMID:26052305

  9. Effects of later-occurring nonlinguistic sounds on speech categorization.

    PubMed

    Wade, Travis; Holt, Lori L

    2005-09-01

    Nonspeech stimuli influence phonetic categorization, but effects observed so far have been limited to precursors' influence on perception of following speech. However, both preceding and following speech affect phonetic categorization. This asymmetry raises questions about whether general auditory processes play a role in context-dependent speech perception. This study tested whether the asymmetry stems from methodological issues or genuine mechanistic limitations. To determine whether and how backward effects of nonspeech context on speech may occur, one experiment examined perception of CVC words with [ga]-[da] series onsets followed by one of two possible embedded tones and one of two possible final consonants. When the tone was separated from the target onset by 100 ms, contrastive effects of tone frequency similar to those of previous studies were observed; however, when the tone was moved closer to the target segment assimilative effects were observed. In another experiment, contrastive effects of a following tone were observed in both CVC words and CV nonwords, although the size of the effects depended on syllable structure. Results are discussed with respect to contrastive mechanisms not speech-specific but operating at a relatively high level, taking into account spectrotemporal patterns occurring over extended periods before and after target events. PMID:16240828

  10. Effect of annealing on photovoltaic performance of fabricated planar organic-inorganic perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Baltakesmez, Ali; Biber, Mehmet; Tüzemen, Sebahattin

    2016-04-01

    We fabricated planar perovskite solar cells used CH3NH3PbI3-xClx for light harvesting to investigate effect of annealing on photovoltaic performance of fabricated device. The devices have an architecture of Glass/ITO/Pedot:PSS/Perovskite/PC61BM/Al. Layers of hole transport (Pedot:PSS), active and electron transport (PC61BM) were prepared from solution based one step deposition method by a spin coater and standard annealing procedure. The current‑voltage curves of devices were measured inside the glovebox using a Keithley 2400 sourcemeter. The cells were illuminated by a solar simulator have optical intensity value of 300 mW/cm2. For the best cells, while PCE value of 5.78% before the annealing, photovoltaic efficiency was improved average 13% delivered a short-circuit current density of 3.20 mA/cm2, open-circuit voltage of 0.82 V and fill factor of 0.74, leading to an efficiency of 6.54% with respect to prior to annealing.

  11. Organic photovoltaics

    NASA Astrophysics Data System (ADS)

    Demming, Anna; Krebs, Frederik C.; Chen, Hongzheng

    2013-12-01

    Energy inflation, the constant encouragement to economize on energy consumption and the huge investments in developing alternative energy resources might seem to suggest that there is a global shortage of energy. Far from it, the energy the Sun beams on the Earth each hour is equivalent to a year's supply, even at our increasingly ravenous rate of global energy consumption [1]. But it's not what you have got it's what you do with it. Hence the intense focus on photovoltaic research to find more efficient ways to harness energy from the Sun. Recently much of this research has centred on organic solar cells since they offer simple, low-cost, light-weight and large-area flexible photovoltaic structures. This issue with guest editors Frederik C Krebs and Hongzheng Chen focuses on some of the developments at the frontier of organic photovoltaic technology. Improving the power conversion efficiency of organic photovoltaic systems, while maintaining the inherent material, economic and fabrication benefits, has absorbed a great deal of research attention in recent years. Here significant progress has been made with reports now of organic photovoltaic devices with efficiencies of around 10%. Yet operating effectively across the electromagnetic spectrum remains a challenge. 'The trend is towards engineering low bandgap polymers with a wide optical absorption range and efficient hole/electron transport materials, so that light harvesting in the red and infrared region is enhanced and as much light of the solar spectrum as possible can be converted into an electrical current', explains Mukundan Thelakkat and colleagues in Germany, the US and UK. In this special issue they report on how charge carrier mobility and morphology of the active blend layer in thin film organic solar cells correlate with device parameters [2]. The work contributes to a better understanding of the solar-cell characteristics of polymer:fullerene blends, which form the material basis for some of the most

  12. Free School Fruit--Sustained Effect 1 Year Later

    ERIC Educational Resources Information Center

    Bere, E.; Veierod, M. B.; Bjelland, M.; Klepp, K.-I.

    2006-01-01

    This study reports the effect of a school-randomized fruit and vegetable intervention consisting of a subscription to the Norwegian School Fruit Programme at no parental cost, and the Fruit and Vegetables Make the Marks (FVMM) educational programme, both delivered in the school year of 2001-02. Nine randomly chosen schools received the…

  13. Transposed-Letter and Laterality Effects in Lexical Decision

    ERIC Educational Resources Information Center

    Perea, Manuel; Fraga, Isabel

    2006-01-01

    Two divided visual field lexical decision experiments were conducted to examine the role of the cerebral hemispheres in transposed-letter similarity effects. In Experiment 1, we created two types of nonwords: nonadjacent transposed-letter nonwords ("TRADEGIA"; the base word was "TRAGEDIA," the Spanish for "TRAGEDY") and two-letter different…

  14. Comparison of Therapeutic Effect of Extracorporeal Shock Wave in Calcific Versus Noncalcific Lateral Epicondylopathy

    PubMed Central

    Park, Jong Wook; Hwang, Ji Hye; Choi, Yoo Seong

    2016-01-01

    Objective To assess the therapeutic effect of extracorporeal shock wave therapy (ESWT) in lateral epicondylopathy with calcification, and compare it to the effect of ESWT in lateral epicondylopathy without calcification. Methods A retrospective study was conducted. Forty-three patients (19 with calcific and 24 with noncalcific lateral epicondylopathy in ultrasound imaging) were included. Clinical evaluations included the 100-point score, Nirschl Pain Phase scale before and after ESWT, and Roles and Maudsley (R&M) scores after ESWT. ESWT (2,000 impulses and 0.06–0.12 mJ/mm2) was performed once a week for 4 weeks. Results The 100-point score and Nirschl Pain Phase scale changed significantly over time (p<0.001), but there was no significant difference between groups (p=0.555). The R&M scores at 3 and 6 months after ESWT were not significantly different between groups. In the presence of a tendon tear, those in the calcific lateral epicondylopathy group showed poor improvement of 100-point scores compared to the noncalcific group (p=0.004). Conclusion This study demonstrated that the therapeutic effect of ESWT in calcific lateral epicondylopathy was not significantly different from that in noncalcific lateral epicondylopathy. When a tendon tear is present, patients with calcific lateral epicondylopathy might show poor prognosis after ESWT relative to patients with noncalcific lateral epicondylopathy. PMID:27152280

  15. Field verification of lateral-torsional coupling effects on rotor instabilities in centrifugal compressors

    NASA Technical Reports Server (NTRS)

    Wachel, J. C.; Szenasi, F. R.

    1980-01-01

    Lateral and torsional vibration data obtained on a centrifugal compressor train which had shaft instabilities and gear failures is examined. The field data verifies that the stability of centrifugal compressors can be adversely affected by coincidence of torsional natural frequencies with lateral instability frequencies. The data also indicates that excitation energy from gear boxes can reduce stability margins if energy is transmitted either laterally or torsionally to the compressors. The lateral and torsional coupling mechanisms of shaft systems is discussed. The coupling mechanisms in a large industrial compressor train are documented and the potential effect on rotor stability is demonstrated. Guidelines are set forth to eliminate these potential problems by minimizing the interaction of torsional and lateral responses and their effect on rotor stability.

  16. Lateralization in appreciation of humor: sex differences vs stimulus effects.

    PubMed

    Gallivan, J

    1997-10-01

    The finding that women rate funnier humorous items with left-ear input, while men give higher ratings with right-ear input has been cited as evidence for a biological basis for sex differences in appreciation of humor. However, in 1991 Gallivan did not find this effect and suggested that the earlier finding could have been due to the use of 'male-oriented' stimuli. In this study, 72 subjects rated the funniness of 32 'female oriented' comedy excerpts, presented monaurally. Women gave higher ratings with right-ear input but men's ratings were not affected by ear of presentation. These findings represent another failure to replicate the earlier-reported hemispheric effect and support the conclusion that it may have been due to the stimuli used. PMID:9347538

  17. Effects of UV on power degradation of photovoltaic modules in combined acceleration tests

    NASA Astrophysics Data System (ADS)

    Ngo, Trang; Heta, Yushi; Doi, Takuya; Masuda, Atsushi

    2016-05-01

    UV exposure and other factors such as high/low temperature, humidity and mechanical stress have been reported to degrade photovoltaic (PV) module materials. By focusing on the combined effects of UV stress and moisture on PV modules, two new acceleration tests of light irradiation and damp heat (DH) were designed and conducted. The effects of UV exposure were validated through a change in irradiation time (UV dosage) and a change of the light irradiation side (glass side vs backsheet side) in the UV-preconditioned DH and cyclic sequential tests, respectively. The chemical corrosion of finger electrodes in the presence of acetic acid generated from ethylene vinyl acetate used as an encapsulant was considered to be the main origin of degradation. The module performance characterized by electroluminescence images was confirmed to correlate with the measured acetic acid concentration and Ag finger electrode resistance.

  18. Performance enhancement of organic photovoltaic devices enabled by Au nanoarrows inducing surface plasmonic resonance effect.

    PubMed

    Li, Shujun; Li, Zhiqi; Zhang, Xinyuan; Zhang, Zhihui; Liu, Chunyu; Shen, Liang; Guo, Wenbin; Ruan, Shengping

    2016-09-21

    The surface plasmon resonance (SPR) effect of metal nanoparticles is widely employed in organic solar cells to enhance device performance. However, the light-harvesting improvement is highly dependent on the shape of the metal nanoparticles. In this study, the significantly enhanced performance upon incorporation of Au nanoarrows in solution-processed organic photovoltaic devices is demonstrated. Incorporating Au nanoarrows into the ZnO cathode buffer layer results in superior broadband optical absorption improvement and a power conversion efficiency of 7.82% is realized with a 27.3% enhancement compared with the control device. The experimental and theoretical results indicate that the introduction of Au nanoarrows not only increases optical trapping by the SPR effect but also facilitates exciton generation, dissociation, and charge transport inside the thin film device. PMID:27531663

  19. Effects of amyotrophic lateral sclerosis sera on cultured cholinergic neurons

    SciTech Connect

    Touzeau, G.; Kato, A.C.

    1983-03-01

    Dissociated monolayer cultures of chick ciliary ganglion neurons have been used to study the effects of control and ALS sera. The cultured neurons survive and extend neurites for a minimum of 2 weeks in a standard tissue culture medium that contains 10% heat-inactivated human serum. Three parameters of the neurons have been examined when cultured in control and ALS sera for 8 to 12 days: (1) neuronal survival, (2) activity of the enzyme choline acetyltransferase, and (3) synthesis of /sup 3/H-acetylcholine using /sup 3/H-choline as precursor. ALS sera cause a small decrease in these three parameters, but this difference is not significant.

  20. Manipulations of attention during eating and their effects on later snack intake.

    PubMed

    Higgs, Suzanne

    2015-09-01

    Manipulation of attention during eating has been reported to affect later consumption via changes in meal memory. The aim of the present studies was to examine the robustness of these effects and investigate moderating factors. Across three studies, attention to eating was manipulated via distraction (via a computer game or TV watching) or focusing of attention to eating, and effects on subsequent snack consumption and meal memory were assessed. The participants were predominantly lean, young women students and the designs were between-subjects. Distraction increased later snack intake and this effect was larger when participants were more motivated to engage with the distracter and were offset when the distractor included food-related cues. Attention to eating reduced later snacking and this effect was larger when participants imagined eating from their own perspective than when they imagined eating from a third person perspective. Meal memory was impaired after distraction but focusing on eating did not affect later meal memory, possibly explained by ceiling effects for the memory measure. The pattern of results suggests that attention manipulations during eating have robust effects on later eating and the effect sizes are medium to large. The data are consistent with previous reports and add to the literature by suggesting that type of attention manipulation is important in determining effects on later eating. The results further suggest that attentive eating may be a useful target in interventions to help with appetite control. PMID:26032197

  1. The Lateralization of Intrinsic Networks in the Aging Brain Implicates the Effects of Cognitive Training

    PubMed Central

    Luo, Cheng; Zhang, Xingxing; Cao, Xinyi; Gan, Yulong; Li, Ting; Cheng, Yan; Cao, Weifang; Jiang, Lijuan; Yao, Dezhong; Li, Chunbo

    2016-01-01

    Lateralization of function is an important organization of the human brain. The distribution of intrinsic networks in the resting brain is strongly related to cognitive function, gender and age. In this study, a longitudinal design with 1 year’s duration was used to evaluate the cognitive training effects on the lateralization of intrinsic networks among healthy older adults. The subjects were divided into two groups randomly: one with multi-domain cognitive training over 3 months and the other as a wait-list control group. Resting state fMRI data were acquired before training and 1 year after training. We analyzed the functional lateralization in 10 common resting state fMRI networks. We observed statically significant training effects on the lateralization of two important RSNs related to high-level cognition: right- and left- frontoparietal networks (FPNs). The lateralization of the left-FPN was retained especially well in the training group but decreased in the control group. The increased lateralization with aging was observed in the cerebellum network (CereN), in which the lateralization was significantly increased in the control group, although the same change tendency was observed in the training group. These findings indicate that the lateralization of the high-level cognitive intrinsic networks is sensitive to multi-domain cognitive training. This study provides neuroimaging evidence to support the hypothesis that cognitive training should have an advantage in preventing cognitive decline in healthy older adults. PMID:26973508

  2. Using Seismic Tomography to Estimate the Magnitude of Lateral Variation in effective Mantle Viscosity

    NASA Technical Reports Server (NTRS)

    Sammis, C.; Ivins, E.

    1994-01-01

    Recent tomographic views of mantle are used to estimate corresponding lateral variations in effective viscosity under the assumption that temperature fluctuations about spherically symmetric mean values are the sole source of shear wave velocity anomalies.

  3. On the Theory of the Shift Linear Photovoltaic Effect in Semiconductors of Tetrahedral Symmetry Under Two-Photon Absorption

    NASA Astrophysics Data System (ADS)

    Rasulov, R. Ya.; Rasulov, V. R.; Eshboltaev, I.

    2016-05-01

    An occurrence of the current of the shift linear photovoltaic effect under two-photon absorption of light in semiconductors without a center of symmetry with a complex band structure is theoretically analyzed. The contributions both from the simultaneous absorption of two photons and successive absorption of two single photons to the photocurrent are taken into account.

  4. Reynolds Number Effects on the Performance of Lateral Control Devices

    NASA Technical Reports Server (NTRS)

    Mineck, Raymond E.

    2000-01-01

    The influence of Reynolds number on the performance of outboard spoilers and ailerons was investigated on a generic subsonic transport configuration in the National Transonic Facility over a chord Reynolds number range 41 from 3x10(exp 6) to 30xl0(exp 6) and a Mach number range from 0.50 to 0.94, Spoiler deflection angles of 0, 10, 15, and 20 deg and aileron deflection angles of -10, 0, and 10 deg were tested. Aeroelastic effects were minimized by testing at constant normalized dynamic pressure conditions over intermediate Reynolds number ranges. Results indicated that the increment in rolling moment due to spoiler deflection generally becomes more negative as the Reynolds number increases from 3x10(exp 6) to 22x10(exp 6) with only small changes between Reynolds numbers of 22x10(exp 6) and 30x10(exp 6). The change in the increment in rolling moment coefficient with Reynolds number for the aileron deflected configuration is generally small with a general trend of increasing magnitude with increasing Reynolds number.

  5. Plasmonic effects of au/ag bimetallic multispiked nanoparticles for photovoltaic applications.

    PubMed

    Sharma, Manisha; Pudasaini, Pushpa Raj; Ruiz-Zepeda, Francisco; Vinogradova, Ekaterina; Ayon, Arturo A

    2014-09-10

    In recent years, there has been considerable interest in the use of plasmons, that is, free electron oscillations in conductors, to boost the performance of both organic and inorganic thin film solar cells. This has been driven by the possibility of employing thin active layers in solar cells in order to reduce materials costs, and is enabled by significant advances in fabrication technology. The ability of surface plasmons in metallic nanostructures to guide and confine light in the nanometer scale has opened up new design possibilities for solar cell devices. Here, we report the synthesis and characterization of highly monodisperse, reasonably stable, multipode Au/Ag bimetallic nanostructures using an inorganic additive as a ligand for photovoltaic applications. A promising surface enhanced Raman scattering (SERS) effect has been observed for the synthesized bimetallic Au/Ag multispiked nanoparticles, which compare favorably well with their Au and Ag spherical nanoparticle counterparts. The synthesized plasmonic nanostructures were incorporated on the rear surface of an ultrathin planar c-silicon/organic polymer hybrid solar cell, and the overall effect on photovoltaic performance was investigated. A promising enhancement in solar cell performance parameters, including both the open circuit voltage (VOC) and short circuit current density (JSC), has been observed by employing the aforementioned bimetallic multispiked nanoparticles on the rear surface of solar cell devices. A power conversion efficiency (PCE) value as high as 7.70% has been measured in a hybrid device with Au/Ag multispiked nanoparticles on the rear surface of an ultrathin, crystalline silicon (c-Si) membrane (∼ 12 μm). This value compares well to the measured PCE value of 6.72% for a similar device without nanoparticles. The experimental observations support the hope for a sizable PCE increase, due to plasmon effects, in thin-film, c-Si solar cells in the near future. PMID:25137194

  6. The effect of lateral banking on the kinematics and kinetics of the lower extremity during lateral cutting movements.

    PubMed

    Wannop, John W; Graf, Eveline S; Stefanyshyn, Darren J

    2014-02-01

    There are many aspects of cutting movements that can limit performance, however, the implementation of lateral banking may reduce some of these limitations. Banking could provide a protective mechanism, placing the foot and ankle in orientations that keep them out of dangerous positions. This study sought to determine the effect of two banking angles on the kinematics and kinetics of the lower extremity during two athletic maneuvers. Kinematic and kinetic data were collected on 10 recreational athletes performing v-cuts and side shuffle movements on different banked surfaces (0°, 10°, 20°). Each sample surface was rigidly attached to the force platform. Joint moments were calculated and compared between conditions using a repeated measures ANOVA. Banking had a pronounced effect on the ankle joint. As banking increased, the amount of joint loading in the transverse and frontal planes decreased likely leading to a reduction in injury risk. Also an increase in knee joint loading in the frontal plane was seen during the 20° bank during the v-cut. Conversely loading in the sagittal plane at the ankle joint increased with banking and coupled with a reorientation of the ground reaction vector may facilitate a performance increase. The current study indicates that the 10° bank may be the optimal bank, in that it decreases ankle joint loading, as well as increases specific performance variables while not increasing frontal plane knee joint loading. If banking could be incorporated in footwear it may be able to provide a protective mechanism for athletes. PMID:24074906

  7. Effects of expiration of the Federal energy tax credit on the National Photovoltaics Program

    NASA Technical Reports Server (NTRS)

    Smith, J. L.

    1984-01-01

    Projected 1986 sales are significantly reduced as a direct result of system price increases following from expiration of the Federal energy tax credits. There would be greatly reduced emphasis on domestic electric utility applications. Indirect effects arising from unrealized economies of scale and reduced private investment in PV research and development (R&D) and in production facilities could have a very large cumulative adverse impact on the U.S. PV industry. The industry forecasts as much as fourfold reduction in 1990 sales if tax credits expire, compared with what sales would be with the credits. Because the National Photovoltaics Program is explicitly structured as a government partnership, large changes in the motivation or funding of either partner can affect Program success profoundly. Reduced industry participation implies that such industry tasks as industrialization and new product development would slow or halt. Those research areas receiving heavy R&D support from private PV manufacturers would be adversely affected.

  8. Effect of operating-point-control strategy on the annual energy production of degraded photovoltaic arrays

    NASA Astrophysics Data System (ADS)

    Branz, H. M.

    1982-09-01

    A new computer simulation of the annual operation of degraded flat-plate photovoltaic (PV) arrays is used to evaluate the need for maximum-power-point tracking in real PV systems. The simulations are based on single-glitch I-V curve shapes rather than particular array degradations, making the data reported applicable to any system whose likely failure modes are predictable and result in single-glitch I-V curves. The simulations show that with a reasonable array wiring strategy, effective maintenance, periodic I-V curve tracing, and avoidance of frequent and serious array shadowing, there is no reason that considerations of degradation should force the adoption of maximum-power-point-tracking power conditioning on a PV system that would otherwise operate economically at fixed voltage.

  9. Effect of electrode geometry on photovoltaic performance of polymer solar cells

    NASA Astrophysics Data System (ADS)

    Li, Meng; Ma, Heng; Liu, Hairui; Wu, Dongge; Niu, Heying; Cai, Wenjun

    2014-10-01

    This paper investigates the impact of electrode geometry on the performance of polymer solar cells (PSCs). The negative electrodes with equal area (0.09 cm2) but different shape (round, oval, square and triangular) are evaluated with respect to short-circuit current density, open-circuit voltage, fill factor and power conversion efficiency of PSCs. The results show that the device with round electrodes gives the best photovoltaic performance; in contrast, the device with triangular electrodes reveals the worst properties. A maximum of almost a 19% increase in power conversion efficiency with a round electrode is obtained in the devices compared with that of the triangular electrode. To conclude, the electrode boundary curvature has a significant impact on the performance of PSCs. The larger curvature, i.e. sharper electrodes edges, perhaps has a negative effect on exciton separation and carrier transport in photoelectric conversion processes.

  10. Al-doping effects on the photovoltaic performance of inverted polymer solar cells

    NASA Astrophysics Data System (ADS)

    Yu, Xuan; Shi, Ya-feng; Yu, Xiao-ming; Zhang, Jian-jun; Ge, Ya-ming; Chen, Li-qiao; Pan, Hong-jun

    2016-03-01

    The properties of Al-doped ZnO (AZO) play an important role in the photovoltaic performance of inverted polymer solar cells (PSCs), which is used as electron transport and hole blocking buffer layers. In this work, we study the effects of Al-doping level in AZO on device performance in detail. Results indicate that the device performance intensely depends on the Al-doping level. The AZO thin films with Al-doping atomic percentage of 1.0% possess the best conductivity. The resulting solar cells show the enhanced short current density and the fill factor ( FF) simultaneously, and the power conversion efficiency ( PCE) is improved by 74%, which are attributed to the reduced carrier recombination and the optimized charge transport and extraction between AZO and the active layer.

  11. Effect of temperature on carrier formation efficiency in organic photovoltaic cells

    SciTech Connect

    Moritomo, Yutaka Yonezawa, Kouhei; Yasuda, Takeshi

    2014-08-18

    The internal quantum efficiency (ϕ{sub IQ}) of an organic photovoltaic cell is governed by plural processes. Here, we propose that ϕ{sub IQ} can be experimentally decomposed into carrier formation (ϕ{sub CF}) and carrier transfer (ϕ{sub CT}) efficiencies. By combining femtosecond time-resolved and electrochemical spectroscopy, we clarified the effect of temperature on ϕ{sub CF} in a regioregular poly(3-hexylthiophene) (rr-P3HT)/[6,6]-phenyl C{sub 61}-butyric acid methyl ester blend film. We found that ϕ{sub CF} (=0.55) at 80 K is the same as that (=0.55) at 300 K. The temperature insensitivity of ϕ{sub CF} indicates that the electron-hole pairs at the D/A interface are seldom subjected to coulombic binding energy.

  12. Effect of temperature on carrier formation efficiency in organic photovoltaic cells

    NASA Astrophysics Data System (ADS)

    Moritomo, Yutaka; Yonezawa, Kouhei; Yasuda, Takeshi

    2014-08-01

    The internal quantum efficiency ( ϕ IQ) of an organic photovoltaic cell is governed by plural processes. Here, we propose that ϕ IQ can be experimentally decomposed into carrier formation ( ϕ CF) and carrier transfer ( ϕ CT) efficiencies. By combining femtosecond time-resolved and electrochemical spectroscopy, we clarified the effect of temperature on ϕ CF in a regioregular poly(3-hexylthiophene) (rr-P3HT)/[6,6]-phenyl C61-butyric acid methyl ester blend film. We found that ϕ CF ( = 0.55 ) at 80 K is the same as that (=0.55) at 300 K. The temperature insensitivity of ϕ CF indicates that the electron-hole pairs at the D/A interface are seldom subjected to coulombic binding energy.

  13. Less is still more: maintenance of the very brief exposure effect 1 year later.

    PubMed

    Siegel, Paul; Warren, Richard

    2013-04-01

    This study tested the hypothesis that an immediate effect of exposure to masked phobic stimuli on avoidance of the corresponding feared object would be maintained 1 year later. Fifty-three spider-phobic participants were identified with a questionnaire and a Behavioral Avoidance Test (BAT) with a live tarantula. One week later, they were administered 1 of 3 types of exposure: very brief (25-ms, masked) or clearly visible (125-ms, unmasked) images of spiders, or very brief images of flowers. They engaged in the BAT again immediately thereafter. One year later, they returned for a follow-up BAT. The immediate effect of exposure to very brief spiders on reducing avoidance of the tarantula was still evident 1 year later. Endurance of an effect by masked stimuli of this duration has not been reported before. Potential theoretical implications are discussed. PMID:23527506

  14. Photovoltaic Effects of Retinal-Related Materials in Langmuir-Blodgett Films

    NASA Astrophysics Data System (ADS)

    Okazaki, Choichiro

    1998-03-01

    Multilayer films consisting of retinal, retinoic acid, and retinol were fabricated using the Langmuir-Blodgett method. It was found for the first time that these three materials in Langmuir-Blodgett films exhibit different photovoltaic characteristics. To study this difference of photovoltaic characteristics, the surface pressure vs area isotherms of these materials were measured and the dipole moment of the materials were calculated.

  15. Giant photovoltaic effect of ferroelectric domain walls in perovskite single crystals

    PubMed Central

    Inoue, Ryotaro; Ishikawa, Shotaro; Imura, Ryota; Kitanaka, Yuuki; Oguchi, Takeshi; Noguchi, Yuji; Miyayama, Masaru

    2015-01-01

    The photovoltaic (PV) effect in polar materials offers great potential for light-energy conversion that generates a voltage beyond the bandgap limit of present semiconductor-based solar cells. Ferroelectrics have received renewed attention because of the ability to deliver a high voltage in the presence of ferroelastic domain walls (DWs). In recent years, there has been considerable debate over the impact of the DWs on the PV effects, owing to lack of information on the bulk PV tensor of host ferroelectrics. In this article, we provide the first direct evidence of an unusually large PV response induced by ferroelastic DWs—termed ‘DW’-PV effect. The precise estimation of the bulk PV tensor in single crystals of barium titanate enables us to quantify the giant PV effect driven by 90° DWs. We show that the DW-PV effect arises from an effective electric field consisting of a potential step and a local PV component in the 90° DW region. This work offers a starting point for further investigation into the DW-PV effect of alternative systems and opens a reliable route for enhancing the PV properties in ferroelectrics based on the engineering of domain structures in either bulk or thin-film form. PMID:26443381

  16. Giant photovoltaic effect of ferroelectric domain walls in perovskite single crystals

    NASA Astrophysics Data System (ADS)

    Inoue, Ryotaro; Ishikawa, Shotaro; Imura, Ryota; Kitanaka, Yuuki; Oguchi, Takeshi; Noguchi, Yuji; Miyayama, Masaru

    2015-10-01

    The photovoltaic (PV) effect in polar materials offers great potential for light-energy conversion that generates a voltage beyond the bandgap limit of present semiconductor-based solar cells. Ferroelectrics have received renewed attention because of the ability to deliver a high voltage in the presence of ferroelastic domain walls (DWs). In recent years, there has been considerable debate over the impact of the DWs on the PV effects, owing to lack of information on the bulk PV tensor of host ferroelectrics. In this article, we provide the first direct evidence of an unusually large PV response induced by ferroelastic DWs—termed ‘DW’-PV effect. The precise estimation of the bulk PV tensor in single crystals of barium titanate enables us to quantify the giant PV effect driven by 90° DWs. We show that the DW-PV effect arises from an effective electric field consisting of a potential step and a local PV component in the 90° DW region. This work offers a starting point for further investigation into the DW-PV effect of alternative systems and opens a reliable route for enhancing the PV properties in ferroelectrics based on the engineering of domain structures in either bulk or thin-film form.

  17. Giant photovoltaic effect of ferroelectric domain walls in perovskite single crystals.

    PubMed

    Inoue, Ryotaro; Ishikawa, Shotaro; Imura, Ryota; Kitanaka, Yuuki; Oguchi, Takeshi; Noguchi, Yuji; Miyayama, Masaru

    2015-01-01

    The photovoltaic (PV) effect in polar materials offers great potential for light-energy conversion that generates a voltage beyond the bandgap limit of present semiconductor-based solar cells. Ferroelectrics have received renewed attention because of the ability to deliver a high voltage in the presence of ferroelastic domain walls (DWs). In recent years, there has been considerable debate over the impact of the DWs on the PV effects, owing to lack of information on the bulk PV tensor of host ferroelectrics. In this article, we provide the first direct evidence of an unusually large PV response induced by ferroelastic DWs-termed 'DW'-PV effect. The precise estimation of the bulk PV tensor in single crystals of barium titanate enables us to quantify the giant PV effect driven by 90° DWs. We show that the DW-PV effect arises from an effective electric field consisting of a potential step and a local PV component in the 90° DW region. This work offers a starting point for further investigation into the DW-PV effect of alternative systems and opens a reliable route for enhancing the PV properties in ferroelectrics based on the engineering of domain structures in either bulk or thin-film form. PMID:26443381

  18. Organic photovoltaics

    NASA Astrophysics Data System (ADS)

    Demming, Anna; Krebs, Frederik C.; Chen, Hongzheng

    2013-12-01

    Energy inflation, the constant encouragement to economize on energy consumption and the huge investments in developing alternative energy resources might seem to suggest that there is a global shortage of energy. Far from it, the energy the Sun beams on the Earth each hour is equivalent to a year's supply, even at our increasingly ravenous rate of global energy consumption [1]. But it's not what you have got it's what you do with it. Hence the intense focus on photovoltaic research to find more efficient ways to harness energy from the Sun. Recently much of this research has centred on organic solar cells since they offer simple, low-cost, light-weight and large-area flexible photovoltaic structures. This issue with guest editors Frederik C Krebs and Hongzheng Chen focuses on some of the developments at the frontier of organic photovoltaic technology. Improving the power conversion efficiency of organic photovoltaic systems, while maintaining the inherent material, economic and fabrication benefits, has absorbed a great deal of research attention in recent years. Here significant progress has been made with reports now of organic photovoltaic devices with efficiencies of around 10%. Yet operating effectively across the electromagnetic spectrum remains a challenge. 'The trend is towards engineering low bandgap polymers with a wide optical absorption range and efficient hole/electron transport materials, so that light harvesting in the red and infrared region is enhanced and as much light of the solar spectrum as possible can be converted into an electrical current', explains Mukundan Thelakkat and colleagues in Germany, the US and UK. In this special issue they report on how charge carrier mobility and morphology of the active blend layer in thin film organic solar cells correlate with device parameters [2]. The work contributes to a better understanding of the solar-cell characteristics of polymer:fullerene blends, which form the material basis for some of the most

  19. Effects of lateral viscosity variations on long-wavelength geoid anomalies and topography

    NASA Technical Reports Server (NTRS)

    Richards, Mark A.; Hager, Bradford H.

    1989-01-01

    The effects of lateral variations in the earth mantle viscosity, due to temperature- or stress-dependent rheology, on the long-wavelength geoid anomalies are examined. Results from simple perturbation theory combined with findings from numerical models for convective flow led to a conclusion that the geoid due to the very longest wavelength convective patterns (l = 2,3) on earth is probably not seriously contaminated by lateral variations due either to temperature or stress dependence. Considerable contamination of the higher-degree geoid (l value of no less than 4) is to be expected due to lateral viscosity variations in phase with the fundamental convection scale length.

  20. Analytical investigation of the effects of lateral connections on the accuracy of population coding

    NASA Astrophysics Data System (ADS)

    Oizumi, Masafumi; Miura, Keiji; Okada, Masato

    2010-05-01

    We studied how lateral connections affect the accuracy of a population code by using a model of orientation selectivity in the primary visual cortex. Investigating the effects of lateral connections on population coding is a complex problem because these connections simultaneously change the shape of tuning curves and correlations between neurons. Both of these changes caused by lateral connections have to be taken into consideration to correctly evaluate their effects. We propose a theoretical framework for analytically computing the Fisher information, which measures the accuracy of a population code, in stochastic spiking neuron models with refractory periods. Within our framework, we accurately evaluated both the changes in tuning curves and correlations caused by lateral connections and their effects on the Fisher information. We found that their effects conflicted with each other and the answer to whether or not the lateral connections increased the Fisher information strongly depended on the intrinsic properties of the model neuron. By systematically changing the coupling strengths of excitations and inhibitions, we found the parameter regions of lateral connectivities where sharpening of tuning curves through Mexican-hat connectivities led to an increase in information, which is in contrast to some previous findings.

  1. Cost-effective applications of photovoltaics for electric utilities: An overview

    SciTech Connect

    Bigger, J.E.

    1993-12-31

    Cost targets for the large-scale entry of photovoltaic (PV) systems keep moving, subject to the vagaries of global oil prices and the economic health of the world. Over the last four decades since a practical PV device was announced, costs have come down by a factor of 20 or more and this downward trend is expected to continue, albeit at a slower pace. Simultaneously, conversion efficiencies have nearly tripled. There are many applications today for which PV is cost-effective. In recognition of this, utility interest in PV is increasing and this is manifested by projects such as PVUSA and Central and South West`s renewable resource development effort. While no major technical barriers for the entry of PV systems have been uncovered, several key issues such as power quality, system reliability, ramp rates, spinning reserve requirements, and misoperation of protection schemes will have to be dealt with as the penetration of this technology increases. PV is still in the evolutionary phase and is expected to grow for several decades to come. Fueled by environmental considerations, interest in PV is showing a healthy rise both in the minds of the public and in the planning realms of the electric power community. In recognition of this, the Energy Development Subcommittee of the IEEE Energy Development and Power Generation Committee organized a Panel Session on photovoltaics applications at the 1993 International Joint Power Generation Conference held in Kansas City, Missouri. Summaries of the four presentations are assembled here for the benefit of the readers of this Review.

  2. Effect of the active damper coil system on the lateral displacement of the magnetically levitated bogie

    SciTech Connect

    Ohashi, S.; Ohsaki, H.; Masada, E.

    1999-09-01

    Numerical simulation of the superconducting magnetically levitated bogie (JR Maglev) has been studied. The active damper coil system is introduced. In this levitation system, the interaction between levitation and guidance is strong. This active damper coil system is designed for reducing the vertical vibration of the bogie. Using the numerical simulation, its effect on the lateral displacement of the bogie is assessed. The active damper coil system for the vertical vibration is shown to works as a passive damper for the lateral vibration.

  3. Photovoltaic cell

    DOEpatents

    Gordon, Roy G.; Kurtz, Sarah

    1984-11-27

    In a photovoltaic cell structure containing a visibly transparent, electrically conductive first layer of metal oxide, and a light-absorbing semiconductive photovoltaic second layer, the improvement comprising a thin layer of transition metal nitride, carbide or boride interposed between said first and second layers.

  4. Effect of the chain length on the thermal and analytical properties of laterally biforked nematogens.

    PubMed

    Dahmane, Mohamed; Athman, Fatiha; Sebih, Saïd; Guermouche, Moulay-Hassane; Bayle, Jean-Pierre; Boudah, Soulimane

    2010-10-15

    Three laterally substituted liquid crystals were synthesized in order to investigate the effect of a lateral biforked chain on the thermal and analytical properties. The mesogenic molecules have the same core containing four aromatic rings connected by two ester and one diazo linkages, they differ by the length of one chain within the lateral biforked substituent. The phase transition temperatures were obtained by polarized light microscopy and differential scanning calorimetry (DSC). The clearing temperature and the nematic range decrease with increasing length of the lateral biforked chain. The stationary phases derived from these nematogens provide excellent resolution of various classes of compounds, including aromatic hydrocarbons (AH), substituted benzenes, polycyclic aromatic hydrocarbons (PAH), phenols and volatile organic compounds (VOC) present in the essential oils. The selectivities of the stationary phases were found to decrease according to the length of the side chain. PMID:20828705

  5. The wavelength dependent photovoltaic effects caused by two different mechanisms in carbon nanotube film/CuO nanowire array heterodimensional contacts

    SciTech Connect

    Xu Jia; Xu Jinliang; Sun Jialin; Wei Jinquan

    2012-06-18

    Hetrodimensional contacts were fabricated by coating double-walled carbon nanotube (CNT) films on CuO nanowire arrays. Wavelength dependent photovoltaic effects by irradiating the devices with 405, 532, and 1064 nm lasers were observed. Two possible mechanisms responsible for the observed results were discussed. Photoexcitations within CuO nanowires and Schottky barriers in the heterojunctions dominate the photovoltaics in the 405 and 532 nm cases. For the 1064 nm case, the photovoltaic is the result of the excitation within the CNTs and of the heterodimensionality effect. Control experiments on CNT film/CuO granular film hetrodimensional contacts further show the relationship between these two mechanisms.

  6. Load controller and method to enhance effective capacity of a photovoltaic power supply

    DOEpatents

    Perez, Richard

    2000-01-01

    A load controller and method are provided for maximizing effective capacity of a non-controllable, renewable power supply coupled to a variable electrical load also coupled to a conventional power grid. Effective capacity is enhanced by monitoring power output of the renewable supply and loading, and comparing the loading against the power output and a load adjustment threshold determined from an expected peak loading. A value for a load adjustment parameter is calculated by subtracting the renewable supply output and the load adjustment parameter from the current load. This value is then employed to control the variable load in an amount proportional to the value of the load control parameter when the parameter is within a predefined range. By so controlling the load, the effective capacity of the non-controllable, renewable power supply is increased without any attempt at operational feedback control of the renewable supply. The renewable supply may comprise, for example, a photovoltaic power supply or a wind-based power supply.

  7. Review of the environmental effects of the Space Station Freedom photovoltaic power module

    NASA Technical Reports Server (NTRS)

    Nahra, Henry K.

    1989-01-01

    An overview is provided of the environment in the low Earth orbit (LEO), the interaction of this environment with the Photovoltaic (PV) Power system of the Space Station Freedom is reviewed, and the environmental programs are described that are designed to investigate the interactions of the LEO environment with the photovoltaic power system. Such programs will support and impact the design of the subsystems of the PV module in order to survive the design lifetime in the LEO natural and induced environment.

  8. Cost effective flat plate photovoltaic modules using light trapping. Final report

    SciTech Connect

    Bain, C.N.; Gordon, B.A.; Knasel, T.M.; Malinowski, R.L.

    1981-04-01

    Work in optical trapping in 'thick films' is described to form a design guide for photovoltaic engineers. A thick optical film can trap light by diffusive reflection and total internal reflection. Light can be propagated reasonably long distances compared with layer thicknesses by this technique. This makes it possible to conduct light from inter-cell and intra-cell areas now not used in photovoltaic modules onto active cell areas.

  9. The effects of laterally varying icy shell structure on the tidal response of Ganymede and Europa

    NASA Astrophysics Data System (ADS)

    A, G.; Wahr, J.; Zhong, S.

    2014-03-01

    We use a finite-element model to solve for the response of Ganymede and Europa to tidal forcing from Jupiter, using various icy shell models with laterally variable (3-D) structure. In all cases, the shell is assumed to be underlain by a liquid-water ocean. Icy shells with laterally varying thickness are derived from a thermal conduction model. Three-dimensional shear modulus profiles for the shell are built either from a conduction model or, for Europa, by assuming a hemispherical difference in composition. Icy shell structures with a nonglobal ocean are built for Ganymede. Using these shell structures to calculate the tidal response of Ganymede and Europa, we conclude the following: (1) the presence of lateral variations in thickness or in shear modulus would not degrade future attempts to use tidal observations to decide on the existence or absence of a liquid ocean and to determine the mean icy shell thickness. (2) Given accurate enough observations, the presence of lateral variations in thickness or in shear modulus could be determined by searching for nondegree-2 components in the tidal response. (3) In the absence of significant viscous convective flow in the shell, the effects of a laterally varying shear modulus on the tidal response would be smaller than those of a laterally varying shell thickness. (4) If the shell is partially grounded, tidal observations of either gravity or uplift would be able to roughly differentiate regions where the ice is grounded from those where it is floating.

  10. Biomechanical effects of lateral and medial wedge insoles on unilateral weight bearing

    PubMed Central

    Sawada, Tomonori; Kito, Nobuhiro; Yukimune, Masaki; Tokuda, Kazuki; Tanimoto, Kenji; Anan, Masaya; Takahashi, Makoto; Shinkoda, Koichi

    2016-01-01

    [Purpose] Lateral wedge insoles reduce the peak external knee adduction moment and are advocated for patients with knee osteoarthritis. However, some patients demonstrate adverse biomechanical effects with treatment. In this study, we examined the immediate effects of lateral and medial wedge insoles under unilateral weight bearing. [Subjects and Methods] Thirty healthy young adults participated in this study. The subjects were assessed by using the foot posture index, and were divided into three groups: normal foot, pronated foot, and supinated foot groups. The knee adduction moment and knee-ground reaction force lever arm under the studied conditions were measured by using a three-dimensional motion capture system and force plates. [Results] In the normal and pronated groups, the change in knee adduction moment significantly decreased under the lateral wedge insole condition compared with the medial wedge insole condition. In the normal group, the change in the knee-ground reaction force lever arm also significantly decreased under the lateral wedge insole condition than under the medial wedge insole condition. [Conclusion] Lateral wedge insoles significantly reduced the knee adduction moment and knee-ground reaction force lever arm during unilateral weight bearing in subjects with normal feet, and the biomechanical effects varied according to individual foot alignment. PMID:26957775

  11. Immediate and 1 week effects of laterally wedge insoles on gait biomechanics in healthy females.

    PubMed

    Weinhandl, Joshua T; Sudheimer, Sarah E; Van Lunen, Bonnie L; Stewart, Kimberly; Hoch, Matthew C

    2016-03-01

    It is estimated that approximately 45% of the U.S. population will develop knee osteoarthritis, a disease that creates significant economic burdens in both direct and indirect costs. Laterally wedged insoles have been frequently recommended to reduce knee abduction moments and to manage knee osteoarthritis. However, it remains unknown whether the lateral wedge will reduce knee abduction moments over a prolonged period of time. Thus, the purposes of this study were to (1) examine the immediate effects of a laterally wedged insole in individuals normally aligned knees and (2) determine prolonged effects after the insole was worn for 1 week. Gait analysis was performed on ten women with and without a laterally wedged insole. After participants wore the wedges for a week, a second gait analysis was performed with and without the insole. The wedged insole did not affect peak knee abduction moment, although there was a significant increase in knee abduction angular impulse after wearing the insoles for 1 week. Furthermore, there was a significant increase in vertical ground reaction force at the instance of peak knee abduction moment with the wedges. While the laterally wedged insole used in the current study did not alter knee abduction moments as expected, other studies have shown alterations. Future studies should also examine a longer acclimation period, the influence of gait speed, and the effect of different shoe types with the insole. PMID:26979900

  12. An Analysis of the Effects of Photovoltaic Energy Systems on Residential Selling Prices in California.

    SciTech Connect

    Cappers, Peter; Wiser, Ryan; Thayer, Mark; Hoen, Ben

    2011-04-12

    An increasing number of homes with existing photovoltaic (PV) energy systems have sold in the U.S., yet relatively little research exists that estimates the marginal impacts of those PV systems on the sales price. A clearer understanding of these effects might influence the decisions of homeowners, home buyers and PV home builders. This research analyzes a large dataset of California homes that sold from 2000 through mid-2009 with PV installed. Across a large number of hedonic and repeat sales model specifications and robustness tests, the analysis finds strong evidence that homes with PV systems sold for a premium over comparable homes without. The effects range, on average, from approximately $3.9 to $6.4 per installed watt (DC), with most models coalescing near $5.5/watt, which corresponds to a premium of approximately $17,000 for a 3,100 watt system. The research also shows that, as PV systems age, the premium enjoyed at the time of home sale decreases. Additionally, existing homes with PV systems are found to have commanded a larger sales price premium than new homes with similarly sized PV systems. Reasons for this discrepancy are suggested, yet further research is warranted in this area as well as a number of other areas that are highlighted.

  13. Photothermoelectric and photovoltaic effects both present in MoS2

    NASA Astrophysics Data System (ADS)

    Zhang, Youwei; Li, Hui; Wang, Lu; Wang, Haomin; Xie, Xiaomin; Zhang, Shi-Li; Liu, Ran; Qiu, Zhi-Jun

    2015-01-01

    As a finite-energy-bandgap alternative to graphene, semiconducting molybdenum disulfide (MoS2) has recently attracted extensive interest for energy and sensor applications. In particular for broad-spectral photodetectors, multilayer MoS2 is more appealing than its monolayer counterpart. However, little is understood regarding the physics underlying the photoresponse of multilayer MoS2. Here, we employ scanning photocurrent microscopy to identify the nature of photocurrent generated in multilayer MoS2 transistors. The generation and transport of photocurrent in multilayer MoS2 are found to differ from those in other low-dimensional materials that only contribute with either photovoltaic effect (PVE) or photothermoelectric effect (PTE). In multilayer MoS2, the PVE at the MoS2-metal interface dominates in the accumulation regime whereas the hot-carrier-assisted PTE prevails in the depletion regime. Besides, the anomalously large Seebeck coefficient observed in multilayer MoS2, which has also been reported by others, is caused by hot photo-excited carriers that are not in thermal equilibrium with the MoS2 lattice.

  14. PASP Plus: An experiment to measure space-environment effects on photovoltaic power subsystems

    NASA Technical Reports Server (NTRS)

    Guidice, Donald A.

    1992-01-01

    The Photovoltaic Array Space Power Plus Diagnostic experiment (PASP Plus) was accepted as part of the APEX Mission payload aboard a Pegastar satellite to be orbited by a Pegasus launch vehicle in late 1992. The mission's elliptical orbit will allow us to investigate both space plasma and space radiation effects. PASP Plus will have eleven types of solar arrays and a full complement of environmental and interactions diagnostic sensors. Measurements of space-plasma interactions on the various solar arrays will be made at large negative voltages (to investigate arcing parameters) and at large positive voltages (to investigate leakage currents) by biasing the arrays to various levels up to -500 and +500 volts. The long-term deterioration in solar array performance caused by exposure to space radiation will also be investigated; radiation dosage will be measured by an electron/proton dosimeter included in the environmental sensor complement. Experimental results from PASP Plus will help establish cause-and-effect relationships and lead to improved design guidelines and test standards for new-technology solar arrays.

  15. Towards cost effective metal precursor sources for future photovoltaic material synthesis: CTS nanoparticles

    NASA Astrophysics Data System (ADS)

    Lokhande, A. C.; Gurav, K. V.; Jo, Eunjin; He, Mingrui; Lokhande, C. D.; Kim, Jin Hyeok

    2016-04-01

    Copper tin sulfide (CTS) is an emerging candidate for solar application due to its favorable band gap and higher optical absorption coefficient. Kuramite-Tetragonal Cu3SnS4 (CTS) monodisperse nanoparticles are prepared by hot injection technique involving cost effective sulfate metal precursor source. A protocol for controlled crystal structure has been demonstrated by variation of cationic Cu:Sn ratio. The crystal structure, size, phase purity, atomic composition, oxidation state and optical properties of the nanoparticles are confirmed from X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman, energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS) and UV-visible spectroscopy, respectively. Hexagonal shaped particles within the size distribution of 7-9 nm with an optimal band gap of 1.28 eV are obtained. XPS study shows the Cu1+, Sn4+ and S2- oxidation states. The effects of influential factors such as metal precursor ratio, metal precursor source, reaction time, heating rate and solvents have been demonstrated systematically on the synthesis of CTS nanoparticles. The plausible mechanism of the formation of CTS nanoparticles has been proposed. The obtained results provide new insight for applying CTS nanoparticles in photovoltaic applications.

  16. On the Theory of the Ballistic Linear Photovoltaic Effect in Semiconductors of Tetrahedral Symmetry Under Two-Photon Absorption

    NASA Astrophysics Data System (ADS)

    Rasulov, R. Ya.; Rasulov, V. R.; Eshboltaev, I.

    2016-07-01

    The ballistic contribution to the current of linear photovoltaic effect under two-photon absorption of light is calculated and theoretically analyzed for the semiconductors of a tetrahedral symmetry with a complex band structure consisting of two closely spaced subbands. The transitions between the branches of one band in cases of the simultaneous absorption of two photons and successive absorption of two single photons are taken into account.

  17. Do photovoltaics have a future

    NASA Technical Reports Server (NTRS)

    Williams, B. F.

    1979-01-01

    There is major concern as to the economic practicality of widespread terrestrial use because of the high cost of the photovoltaic arrays themselves. Based on their high efficiency, photovoltaic collectors should be one of the cheapest forms of energy generators known. Present photovoltaic panels are violating the trend of lower costs with increasing efficiency due to their reliance on expensive materials. A medium technology solution should provide electricity competitive with the existing medium to high technology energy generators such as oil, coal, gas, and nuclear fission thermal plants. Programs to reduce the cost of silicon and develop reliable thin film materials have a realistic chance of producing cost effective photovoltaic panels.

  18. Differential effects of GDF5 on the medial and lateral rat ventral mesencephalon.

    PubMed

    Clayton, Kevin B; Sullivan, Aideen M

    2007-11-12

    Growth/differentiation factor 5 (GDF5) is a member of the transforming growth factor-beta (TGF-beta) superfamily that has potent neurotrophic and protective effects on dopaminergic neurones and is expressed in the developing rat substantia nigra (the ventral mesencephalon; VM). GDF5 has the potential to be used in the treatment of Parkinson's disease (PD), a neurodegenerative disorder characterised by the selective degeneration of nigrostriatal dopaminergic neurones. One therapy being explored for PD involves transplantation of fetal VM tissue into the striatum in order to replace lost dopaminergic neurones. The majority of transplantation studies have used transplants incorporating the whole VM. The principal location of dopaminergic neurones in the E14 rat VM is in the medial VM. In the present study, the effects of GDF5 on cultures prepared from medial, lateral and whole E14 rat VM tissue were compared. GDF5 treatment increased the number of dopaminergic neurones in whole and lateral, but not in medial, VM cultures, whereas it increased total cell number in medial, but not in whole or lateral, VM cultures. RT-PCR studies showed that the receptors for GDF5 were differentially expressed in E14 VM; the expression of BMPR-IB and Ror2 was low in medial but high in lateral VM tissue. This study suggests that GDF5 increases the number of dopaminergic neurones in whole VM cultures by acting on BMPR-IB and Ror2-expressing cells in the lateral VM. PMID:17935884

  19. Effect of vertical and lateral coupling between tyre and road on vehicle rollover

    NASA Astrophysics Data System (ADS)

    Li, Yinong; Sun, Wei; Huang, Jingying; Zheng, Ling; Wang, Yanyang

    2013-08-01

    The vehicle stability involves many aspects, such as the anti-rollover stability in extreme steering operations and the vehicle lateral stability in normal steering operations. The relationships between vehicle stabilities in extreme and normal circumstances obtain less attention according to the present research works. In this paper, the coupling interactions between vehicle anti-rollover and lateral stability, as well as the effect of road excitation, are taken into account on the vehicle rollover analysis. The results in this paper indicate that some parameters influence the different vehicle stabilities diversely or even contradictorily. And it has been found that there are contradictions between the vehicle rollover mitigation performance and the lateral stability. The direct cause for the contradiction is the lateral coupling between tyres and road. Tyres with high adhesion capacity imply that the vehicle possesses a high performance ability to keep driving direction, whereas the rollover risk of this vehicle increases due to the greater lateral force that tyres can provide. Furthermore, these contradictions are intensified indirectly by the vertical coupling between tyres and road. The excitation from road not only deteriorates the tyres' adhesive condition, but also has a considerable effect on the rollover in some cases.

  20. Effectiveness of fine-needle aspiration cytology in the diagnosis of lateral cervical nonthyroid tumors

    PubMed Central

    Iacob, Alina; Zazgyva, Ancuta; Ormenişan, Alina; Mezei, Tibor; Sin, Anca; Tilinca, Mariana

    2016-01-01

    Abstract Given that the clinical and radiological examinations of lateral cervical masses are not always sufficient for deciding on appropriate management, the cytological examination of the material obtained by fine-needle aspiration might be an efficient tool in the preoperative investigation of these lesions. In this prospective cross-sectional study we evaluated the efficacy and diagnostic accuracy of fine-needle aspiration cytology in the assessment of lateral cervical nonthyroid tumors, by comparing its results with those of histopathology. A total of 58 patients with lateral cervical masses were included. Preoperative cytological results were compared with the histopathologic examination of surgical specimens. Both cytology and histology indicated that malignant tumors outnumbered benign lesions (62% vs 38%), with 88.9% of malignancies presenting in patients aged >50 years, but cytology was less effective at differentiating between benign and nontumor lesions. Cytology had 76.5% specificity and 78.1% sensitivity for identifying malignant lateral cervical lesions, and there was a concordance between the two diagnostic tests (McNemar test, P = 0.17, κ = 0.50, P <0.001). Fine-needle aspiration cytology is a simple, quick, and effective procedure that can aid in the preoperative evaluation of lateral cervical masses by differentiating benign tumors and inflammatory processes from malignancies and thus help in determining a subsequent therapeutic strategy. PMID:27495074

  1. Lateral tip control effects in critical dimension atomic force microscope metrology: the large tip limit

    NASA Astrophysics Data System (ADS)

    Dixson, Ronald G.; Orji, Ndubuisi G.; Goldband, Ryan S.

    2016-01-01

    Sidewall sensing in critical dimension atomic force microscopes (CD-AFMs) usually involves continuous lateral dithering of the tip or the use of a control algorithm and fast response piezoactuator to position the tip in a manner that resembles touch-triggering of coordinate measuring machine probes. All methods of tip position control, however, induce an effective tip width that may deviate from the actual geometrical tip width. Understanding the influence and dependence of the effective tip width on the dither settings and lateral stiffness of the tip can improve the measurement accuracy and uncertainty estimation for CD-AFM measurements. Since CD-AFM typically uses tips that range from 15 to 850 nm in geometrical width, the behavior of effective tip width throughout this range should be understood. The National Institute of Standards and Technology (NIST) has been investigating the dependence of effective tip width on the dither settings and lateral stiffness of the tip, as well as the possibility of material effects due to sample composition. For tip widths of 130 nm and lower, which also have lower lateral stiffness, the response of the effective tip width to lateral dither is greater than for larger tips. However, we have concluded that these effects will not generally result in a residual bias, provided that the tip calibration and sample measurement are performed under the same conditions. To confirm that our prior conclusions about the dependence of effective tip width on lateral stiffness are valid for large CD tips, we recently performed experiments using a very large non-CD tip with an etched plateau of ˜2-μm width. The effective lateral stiffness of these tips is at least 20 times greater than typical CD-AFM tips, and these results supported our prior conclusions about the expected behavior for larger tips. The bottom-line importance of these latest observations is that we can now reasonably conclude that a dither slope of 3 nm/V is the baseline

  2. Lateral Tip Control Effects in CD-AFM Metrology: The Large Tip Limit

    PubMed Central

    Dixson, Ronald G.; Orji, Ndubuisi G.; Goldband, Ryan S.

    2016-01-01

    Sidewall sensing in critical dimension atomic force microscopes (CD-AFMs) usually involves continuous lateral dithering of the tip or the use of a control algorithm and fast response piezo actuator to position the tip in a manner that resembles touch-triggering of coordinate measuring machine (CMM) probes. All methods of tip position control, however, induce an effective tip width that may deviate from the actual geometrical tip width. Understanding the influence and dependence of the effective tip width on the dither settings and lateral stiffness of the tip can improve the measurement accuracy and uncertainty estimation for CD-AFM measurements. Since CD-AFM typically uses tips that range from 15 nm to 850 nm in geometrical width, the behavior of effective tip width throughout this range should be understood. The National Institute of Standards and Technology (NIST) has been investigating the dependence of effective tip width on the dither settings and lateral stiffness of the tip, as well as the possibility of material effects due to sample composition. For tip widths of 130 nm and lower, which also have lower lateral stiffness, the response of the effective tip width to lateral dither is greater than for larger tips. However, we have concluded that these effects will not generally result in a residual bias, provided that the tip calibration and sample measurement are performed under the same conditions. To validate that our prior conclusions about the dependence of effective tip width on lateral stiffness are valid for large CD-tips, we recently performed experiments using a very large non-CD tip with an etched plateau of approximately 2 μm width. The effective lateral stiffness of these tips is at least 20 times greater than typical CD-AFM tips, and these results supported our prior conclusions about the expected behavior for larger tips. The bottom-line importance of these latest observations is that we can now reasonably conclude that a dither slope of 3 nm

  3. Photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Groth, H.

    1982-11-01

    The utilization of photovoltaic generators in measuring and signalling installations, communication systems, water pumping, and electric power plants is discussed. The advantages of solar generators over conventional power supply equipment are outlined.

  4. A photovoltaic effect in the metal-high-resistive GaAs:Cr contact

    NASA Astrophysics Data System (ADS)

    Budnitskii, D. L.; Novikov, V. A.; Prudaev, I. A.; Тоlbanov, О. P.; Yaskevich, Т. М.

    2012-12-01

    The results of studies of photovoltaic effect in the contacts of a number of metals with high-resistive GaAs:Cr are reported. High-resistive (HR) GaAs was obtained by diffusion of chromium in n-GaAs. V, Cr, and Al were used as metals. In was employed in order to produce ohmic contacts. Photovoltage was excited by red light (hν = 1.85 eV), and the excitation intensity amounted to 1.5ṡ1021 сm-2ṡs-1. Photovoltage was measured in the presence of asymmetric pairs of contacts to HR-GaAs: V-In, Cr-In, and Al-In. It is shown that V, Cr, and Al form barriers for electrons in the contact with high-resistive GaAs:Cr. The photovoltage of the contacts is determined by the inversion of conductivity type of the near-surface GaAs layer under the metal contact. The hole concentration in the inversion layer can be as high as ≈1015 сm-3. An In contact to high-resistive GaAs:Cr is an ohmic injecting contact for electrons with the barrier height for holes ≈0.9 eV.

  5. Large enhancement of the photovoltaic effect in ferroelectric complex oxides through bandgap reduction

    PubMed Central

    An, Hyunji; Han, Jun Young; Kim, Bongjae; Song, Jaesun; Jeong, Sang Yun; Franchini, Cesare; Bark, Chung Wung; Lee, Sanghan

    2016-01-01

    Tuning the bandgap in ferroelectric complex oxides is a possible route for improving the photovoltaic activity of materials. Here, we report the realization of this effect in epitaxial thin films of the ferroelectric complex oxide Bi3.25La0.75Ti3O12 (BLT) suitably doped by Fe and Co. Our study shows that Co (BLCT) doping and combined Fe, Co (BLFCT) doping lead to a reduction of the bandgap by more than 1 eV compared to undoped BLT, accompanied by a surprisingly more efficient visible light absorption. Both BLCT and BLFCT films can absorb visible light with a wavelength of up to 500 nm while still exhibiting ferroelectricity, whereas undoped BLT only absorbs UV light with a wavelength of less than 350 nm. Correlated with its bandgap reduction, the BLFCT film shows a photocurrent density enhanced by 25 times compared to that of BLT films. Density functional theory calculations indicate that the bandgap contraction is caused by the formation of new energy states below the conduction bands due to intermixed transition metal dopants (Fe, Co) in BLT. This mechanism of tuning the bandgap by simple doping can be applied to other wide-bandgap complex oxides, thereby enabling their use in solar energy conversion or optoelectronic applications. PMID:27313099

  6. Large enhancement of the photovoltaic effect in ferroelectric complex oxides through bandgap reduction.

    PubMed

    An, Hyunji; Han, Jun Young; Kim, Bongjae; Song, Jaesun; Jeong, Sang Yun; Franchini, Cesare; Bark, Chung Wung; Lee, Sanghan

    2016-01-01

    Tuning the bandgap in ferroelectric complex oxides is a possible route for improving the photovoltaic activity of materials. Here, we report the realization of this effect in epitaxial thin films of the ferroelectric complex oxide Bi3.25La0.75Ti3O12 (BLT) suitably doped by Fe and Co. Our study shows that Co (BLCT) doping and combined Fe, Co (BLFCT) doping lead to a reduction of the bandgap by more than 1 eV compared to undoped BLT, accompanied by a surprisingly more efficient visible light absorption. Both BLCT and BLFCT films can absorb visible light with a wavelength of up to 500 nm while still exhibiting ferroelectricity, whereas undoped BLT only absorbs UV light with a wavelength of less than 350 nm. Correlated with its bandgap reduction, the BLFCT film shows a photocurrent density enhanced by 25 times compared to that of BLT films. Density functional theory calculations indicate that the bandgap contraction is caused by the formation of new energy states below the conduction bands due to intermixed transition metal dopants (Fe, Co) in BLT. This mechanism of tuning the bandgap by simple doping can be applied to other wide-bandgap complex oxides, thereby enabling their use in solar energy conversion or optoelectronic applications. PMID:27313099

  7. Electron-hole transport and photovoltaic effect in gated MoS2 Schottky junctions

    NASA Astrophysics Data System (ADS)

    Fontana, Marcio; Deppe, Tristan; Boyd, Anthony K.; Rinzan, Mohamed; Liu, Amy Y.; Paranjape, Makarand; Barbara, Paola

    2013-04-01

    Semiconducting molybdenum disulfphide has emerged as an attractive material for novel nanoscale optoelectronic devices due to its reduced dimensionality and large direct bandgap. Since optoelectronic devices require electron-hole generation/recombination, it is important to be able to fabricate ambipolar transistors to investigate charge transport both in the conduction band and in the valence band. Although n-type transistor operation for single-layer and few-layer MoS2 with gold source and drain contacts was recently demonstrated, transport in the valence band has been elusive for solid-state devices. Here we show that a multi-layer MoS2 channel can be hole-doped by palladium contacts, yielding MoS2 p-type transistors. When two different materials are used for the source and drain contacts, for example hole-doping Pd and electron-doping Au, the Schottky junctions formed at the MoS2 contacts produce a clear photovoltaic effect.

  8. Electron-hole transport and photovoltaic effect in gated MoS2 Schottky junctions

    NASA Astrophysics Data System (ADS)

    Boyd, Anthony; Fontana, Marcio; Deppe, Tristan; Rinzan, Mohamed; Liu, Amy; Paranjape, Makarand; Barbara, Paola

    2013-03-01

    Atomically thin molybdenum disulfide has emerged as an attractive material for novel nanoscale optoelectronic devices due to its reduced dimensionality and large direct bandgap. Since optoelectronic devices require electron-hole generation/recombination, it is important to be able to fabricate ambipolar transistors to investigate charge transport both in the conduction band and in the valence band. Although n-type transistor operation for single-layer and few-layer MoS2 with gold source and drain contacts was recently demonstrated..., transport in the valence band has been elusive for solid-state devices. Here we show that a multi-layer MoS2 channel can be hole-doped by palladium contacts, yielding MoS2 p-type transistors. When two different materials are used for the source and drain contacts, for example hole-doping Pd and electron-doping Au, the Schottky junctions formed at the MoS2 contacts produce a clear photovoltaic effect. Work Funded by NSF, DMR 1008242.

  9. The effects of lunar dust accumulation on the performance of photovoltaic arrays

    NASA Technical Reports Server (NTRS)

    Katzan, Cynthia M.; Brinker, David J.; Kress, Robert

    1991-01-01

    Lunar base activity, particularly rocket launch and landing, will suspend and transport lunar dust. From preliminary models, the resulting dust accumulation can be significant, even as far as 2 km from the source. For example, at 2 km approximately 0.28 mg/sq cm of dust is anticipated to accumulate after only 10 surface missions with a 26,800 N excursion vehicle. The possible associated penalties in photovoltaic array performance were therefore the subject of experimental as well as theoretical investigation. To evaluate effects of dust accumulation on relative power output, current-voltage characteristics of dust-covered silicon cells were determined under the illumination of a Spectrolab X-25L solar simulator. The dust material used in these experiments was a terrestrial basalt which approximated lunar soil in particle size and composition. Cell short circuit current, an indicator of the penetrating light intensity, was found to decrease exponentially with dust accumulation. This was predicted independently by modeling the light occlusion caused by a growing layer of dust particles. Moreover, the maximum power output of dust-covered cells, derived from the I-V curves, was also found to degrade exponentially. Experimental results are presented and potential implications discussed.

  10. Effect of particle size of Martian dust on the degradation of photovoltaic cell performance

    NASA Technical Reports Server (NTRS)

    Gaier, James R.; Perez-Davis, Marla E.

    1991-01-01

    Glass coverglass and SiO2 covered and uncovered silicon photovoltaic (PV) cells were subjected to conditions simulating a Mars dust storm, using the Martian Surface Wind Tunnel, to assess the effect of particle size on the performance of PV cells in the Martian environment. The dust used was an artificial mineral of the approximate elemental composition of Martian soil, which was sorted into four different size ranges. Samples were tested both initially clean and initially dusted. The samples were exposed to clear and dust laden winds, wind velocities varying from 23 to 116 m/s, and attack angles from 0 to 90 deg. It was found that transmittance through the coverglass approximates the power produced by a dusty PV cell. Occultation by the dust was found to dominate the performance degradation for wind velocities below 50 m/s, whereas abrasion dominates the degradation at wind velocities above 85 m/s. Occultation is most severe at 0 deg (parallel to the wind), is less pronounced from 22.5 to 67.5 deg, and is somewhat larger at 90 deg (perpendicular to the wind). Abrasion is negligible at 0 deg, and increases to a maximum at 90 deg. Occultation is more of a problem with small particles, whereas large particles (unless they are agglomerates) cause more abrasion.

  11. Effect of surfactant on TPP (tetraphenylporphyrin)-SnO[sub 2] photovoltaic cell

    SciTech Connect

    Bi, Z.; Li, Y. . Inst. of Photographic Chemistry); Tien, H.T. . Dept. of Biophysics)

    1994-02-01

    A simple photovoltaic cell has been constructed by using Nesa glass coated with SnO[sub 2] on both sides as transparent electrodes, one of which is further coated with a photosensitizing dyestuff, tetraphenylporphyrin (TPP), forming the photocathode, and by using an aqueous solution of Fe[sup 3+]/Fe[sup 2+] redox couple as the electrolytic solution. By adding an anionic surfactant, sodium dodecyl sulfonate (SDS), to the solution, both the photovoltage and the photocurrent of the cell are markedly enhanced. The power conversion efficiency of the SDS-containing cell is about eight times the value of the original cell. Other anionic surfactants (e.g., sodium octyl sulfate and sodium dodecyl sulfate) have a similar effect. From the data of the surface tension and the contact angle which the authors have measured, the interface excess of SDS at the interface between the TPP film of the photocathode and the solution has been calculated. The relationship between the photovoltage of the cell and the conformation of the adsorbed SDS molecules at the interface as well as the critical micelle concentration (CMC) of SDS in the solution are discussed. Other types of surfactant were also tested.

  12. Metal-assisted chemical etching of Ge surface and its effect on photovoltaic devices

    NASA Astrophysics Data System (ADS)

    Lee, Seunghyo; Choo, Hyeokseong; Kim, Changheon; Oh, Eunseok; Seo, Dongwan; Lim, Sangwoo

    2016-05-01

    Ge surfaces were etched by means of metal-assisted chemical etching (MaCE). The behavior of the MaCE reaction in diluted H2O2 was compared with that of a conventional etchant of HF/H2O2/H2O mixture (FPM). Herein we first report that a pyramidal structure on Ge (0 0 1) can be prepared by MaCE in dilute H2O2 solution, without the use of HF. Contrastingly, an octagonal trench structure was prepared by 4/5/1 FPM treatment of Ge (0 0 1) surface. This octagonal structure consisted of a square base, four large facets connected to the base, and other four small facets adjacent to the four large facets, which were considered to be (0 0 1), {1 1 0}, and {1 1 1}, respectively. The octagonal trench was formed as a result of the difference in etch rate of Ge depending on the orientation: {1 0 0} > {1 1 0} > {1 1 1}. Ge surfaces treated by MaCE exhibited improved solar cell efficiency due to their improved light absorption, which led to significant increases in the cells' short circuit current and fill factor. The results suggest that optimized MaCE procedures can be an effective method to improve the performance of Ge-based photovoltaic devices.

  13. Optical spacing effect in organic photovoltaic cells incorporating a dilute acceptor layer

    SciTech Connect

    Menke, S. Matthew; Lindsay, Christopher D.; Holmes, Russell J.

    2014-06-16

    The addition of spacing layers in organic photovoltaic cells (OPVs) can enhance light absorption by optimizing the spatial distribution of the incident optical field in the multilayer structure. We explore the optical spacing effect in OPVs achieved using a diluted electron acceptor layer of C{sub 60}. While optical spacing is often realized by optimizing buffer layer thickness, we find that optical spacing via dilution leads to cells with similar or enhanced photocurrent. This is observed despite a smaller quantity of absorbing molecules, suggesting a more efficient use of absorbed photons. In fact, dilution is found to concentrate optical absorption near the electron donor-acceptor interface, resulting in a marked increase in the exciton diffusion efficiency. Contrasting the use of changes in thickness to engineer optical absorption, the use of dilution does not significantly alter the overall thickness of the OPV. Optical spacing via dilution is shown to be a viable alternative to more traditional optical spacing techniques and may be especially useful in the continued optimization of next-generation, tandem OPVs where it is important to minimize competition for optical absorption between individual sub-cells.

  14. Effect of prosthodontic planning on lateral occlusion scheme: a comparison between conventional and digital planning

    PubMed Central

    ABDUO, Jaafar; BENNAMOUN, Mohammed; TENNANT, Marc; McGEACHIE, John

    2015-01-01

    Recently, digital wax-up is proposed as a tool to aid prosthodontic planning. However, there are no data about the effect of prosthodontic planning on lateral occlusion scheme. Objective : This study aims to evaluate the impact of conventional and digital prosthodontic planning on lateral occlusion scheme. Material and Methods : Dental models of 10 patients were collected. All models had Angle Class I occlusion and were undergoing prosthodontic treatment that would influence the lateral occlusion scheme. Each set of models had received both conventional wax-up and digital wax-up. In relation to the lateral occlusion scheme, the following variables were evaluated: the prevalence of the different lateral occlusion scheme, number of contacting teeth and percentage of each contacting tooth. Four excursive positions on the working side were included: 0.5, 1.0, 2.0 and 3.0 mm from the maximal intercuspation position. Results : The lateral occlusion scheme of the two wax-up models was subjected to alterations following excursion. There was a tendency for the prevalence of canine-guided occlusion to increase and for the prevalence of group function occlusion to decrease with increasing excursion. The number of contacting teeth was decreasing with the increasing magnitude of excursion. For the 0.5 mm and 1.0 mm positions, the two wax-ups had significantly greater contacts than the pre-treatment models, while at the 2.0 mm and 3.0 mm positions, all the models were similar. For all models, canines were the most commonly contacting teeth, followed by the teeth adjacent to them. No difference was observed between the two wax-ups in relation to the number of contacting teeth. Conclusion : Although the prosthodontic planning had influenced the pattern of the lateral occlusion scheme and contacts, there was no difference between the conventional and digital prosthodontic planning. PMID:26018312

  15. The Effects of Bilingualism on Efficiency and Lateralization of Attentional Networks

    ERIC Educational Resources Information Center

    Marzecova, Anna; Asanowicz, Dariusz; Kriva, L'Uba; Wodniecka, Zofia

    2013-01-01

    The present study investigated the impact of bilingualism on efficiency of alerting, orienting and executive attention by means of the Lateralized Attention Network Test (LANT). Young adult bilinguals who had been exposed to their second language before the age of four years showed a reduced conflict cost and a larger alerting effect in terms of…

  16. Optically Induced PN Junction Diode and Photovoltaic Response on Ambipolar MoSe2 Field-effect Transistor

    NASA Astrophysics Data System (ADS)

    Pradhan, Nihar; Lu, Zhengguang; Rhodes, Daniel; Terrones, Mauricio; Smirnov, Dmitry; Balicas, Luis

    2015-03-01

    Transition metal dichalcogenides (TMDs) have emerged as an attractive material for electronic and optoelectronic devices due to their sizable band gap, flexibility and reduced dimensionality, which makes them promising candidates for applications in translucent optoelectronics components, such as solar cells and light emitting diodes. Here, we present an optically induced diode like response and concomitant photovoltaic effect in few-atomic layers molybdenum diselenide (MoSe2) field-effect transistors. Compared to recently reported PN junctions based on TMDs, ambipolar MoSe2 shows nearly ideal diode rectification under illumination, with a sizable photovoltaic efficiency. The observed light induced diode response under fixed gate voltage, yields a maximum open circuit voltage 0.28V and short circuit current 230nA at 30uW incident laser power. The sense of current rectification can be altered by changing the polarity of the applied gate voltage (Vbg) . At Vbg = 0V the highest electrical power obtained is 175pW corresponding to a maximum photovoltaic efficiency of 0.01%. These values increased to 11nW and 0.05% under a Vbg = -7.5V. At an excitation voltage 1V we observed maximum photocurrent responsivity surpassing 100mA/W with corresponding external quantum efficiency ~ 30%.

  17. Effects of structural characterizations on fragility functions of bridges subject to seismic shaking and lateral spreading

    NASA Astrophysics Data System (ADS)

    Zhang, Jian; Huo, Yili; Brandenberg, Scott J.; Kashighandi, Pirooz

    2008-12-01

    This paper evaluates the seismic vulnerability of different classes of typical bridges in California when subjected to seismic shaking or liquefaction-induced lateral spreading. The detailed structural configurations in terms of superstructure type, connection, continuity at support and foundation type, etc. render different damage resistant capability. Six classes of bridges are established based on their anticipated failure mechanisms under earthquake shaking. The numerical models that are capable of simulating the complex soil-structure interaction effects, nonlinear behavior of columns and connections are developed for each bridge class. The dynamic responses are obtained using nonlinear time history analyses for a suite of 250 earthquake motions with increasing intensity. An equivalent static analysis procedure is also implemented to evaluate the vulnerability of the bridges when subjected to liquefaction-induced lateral spreading. Fragility functions for each bridge class are derived and compared for both seismic shaking (based on nonlinear dynamic analyses) and lateral spreading (based on equivalent static analyses) for different performance states. The study finds that the fragility functions due to either ground shaking or lateral spreading show significant correlation with the structural characterizations, but differences emerge for ground shaking and lateral spreading conditions. Structural properties that will mostly affect the bridges’ damage resistant capacity are also identified.

  18. Laterality effects in normal subjects' recognition of familiar faces, voices and names. Perceptual and representational components.

    PubMed

    Gainotti, Guido

    2013-06-01

    A growing body of evidence suggests that a different hemispheric specialization may exist for different modalities of person identification, with a prevalent right lateralization of the sensory-motor systems allowing face and voice recognition and a prevalent left lateralization of the name recognition system. Data supporting this claim concern, however, much more disorders of familiar people recognition observed in patients with focal brain lesions than results of experimental studies conducted in normal subjects. These last data are sparse and in part controversial, but are important from the theoretical point of view, because it is not clear if hemispheric asymmetries in the recognition of faces, voices and names are limited to their perceptual processing, or also extend to the domain of their cortical representations. The present review has tried to clarify this issues, taking into account investigations that have evaluated in normal subjects laterality effects in recognition of familiar names, faces and voices, by means of behavioural, neurophysiological and neuroimaging techniques. Results of this survey indicate that: (a) recognition of familiar faces and voices show a prevalent right lateralization, whereas recognition of familiar names is lateralized to the left hemisphere; (b) the right hemisphere prevalence is greater in tasks involving familiar than unfamiliar faces and voices, and the left hemisphere superiority is greater in the recognition of familiar than unfamiliar names. Taken together, these data suggest that hemispheric asymmetries in the recognition of faces, voices and names are not limited to their perceptual processing, but also extend to the domain of their cortical representations. PMID:23542500

  19. Neuropsychiatric effects of neurodegeneration of the medial versus lateral ventral prefrontal cortex in humans.

    PubMed

    Huey, Edward D; Lee, Seonjoo; Brickman, Adam M; Manoochehri, Masood; Griffith, Erica; Devanand, D P; Stern, Yaakov; Grafman, Jordan

    2015-12-01

    Animal evidence suggests that a brain network involving the medial and rostral ventral prefrontal cortex (PFC) is central for threat response and arousal and a network involving the lateral and caudal PFC plays an important role in reward learning and behavioral control. In this study, we contrasted the neuropsychiatric effects of degeneration of the medial versus lateral PFC in 43 patients with Frontotemporal dementia (FTD) and 11 patients with Corticobasal Syndrome (CBS) using MRI, the Neuropsychiatric Inventory (NPI), and the Sorting, Tower, Twenty Questions, and Fluency tests of the Delis-Kaplan Executive Function System (D-KEFS). Deviations in MRI grey matter volume from 86 age-matched healthy control subjects were determined for the patients using FreeSurfer. Multivariate regression was used to determine which brain areas were associated with specific neuropsychiatric and cognitive symptoms. Decreased grey matter volume of the right medial ventral PFC was associated with increased anxiety and apathy, decreased volume of the right lateral ventral PFC with apathy and inappropriate repetitive behaviors, and of the left lateral ventral PFC with poor performance on the sorting and Twenty Questions task in patients with FTD and CBS. Similar to in animal studies, damage to the medial OFC appears to be associated with a disruption of arousal, and damage to the lateral OFC appears to be associated with deficits in trial-and-error learning and behavioral dysregulation. Studies of brain dysfunction in humans are valuable to bridge animal and human neuropsychiatric research. PMID:26343341

  20. Large area InN terahertz emitters based on the lateral photo-Dember effect

    SciTech Connect

    Wallauer, Jan Grumber, Christian; Walther, Markus; Polyakov, Vladimir; Iannucci, Robert; Cimalla, Volker; Ambacher, Oliver

    2015-09-14

    Large area terahertz emitters based on the lateral photo-Dember effect in InN (indium nitride) are presented. The formation of lateral photo-Dember currents is induced by laser-illumination through a microstructured metal cover processed onto the InN substrate, causing an asymmetry in the lateral photogenerated charge carrier distribution. Our design uses simple metal structures, which are produced by conventional two-dimensional micro-structuring techniques. Having favoring properties as a photo-Dember material InN is particularly well-suited as a substrate for our emitters. We demonstrate that the emission intensity of the emitters can be significantly influenced by the structure of the metal cover leaving room for improvement by optimizing the masking structures.

  1. Prospective Control in Catching: The Persistent Angle-of-Approach Effect in Lateral Interception

    PubMed Central

    Ledouit, Simon; Casanova, Remy; Zaal, Frank T. J. M.; Bootsma, Reinoud J.

    2013-01-01

    In lateral interception tasks balls converging onto the same interception location via different trajectories give rise to systematic differences in the kinematics of hand movement. While it is generally accepted that this angle-of-approach effect reflects the prospective (on-line) control of movement, controversy exists with respect to the information used to guide the hand to the future interception location. Based on the pattern of errors observed in a task requiring visual extrapolation of line segments to their intersection with a second line, angle-of-approach effects in lateral interception have been argued to result from perceptual biases in the detection of information about the ball's future passing distance along the axis of hand movement. Here we demonstrate that this account does not hold under experimental scrutiny: The angle-of-approach effect still emerged when participants intercepted balls moving along trajectories characterized by a zero perceptual bias with respect to the ball's future arrival position (Experiment 4). Designing and validating such bias-controlled trajectories were done using the line-intersection extrapolation task (Experiments 2 and 3). The experimental set-up used in the present series of experiments was first validated for the lateral interception and the line-intersection extrapolation tasks: In Experiment 1 we used rectilinear ball trajectories to replicate the angle-of-approach effect in lateral interception of virtual balls. Using line segments extracted from these rectilinear ball trajectories, in Experiment 2 we replicated the reported pattern of errors in the estimated locus of intersection with the axis of hand movement. We used these errors to develop a set of bias-free trajectories. Experiment 3 confirmed that the perceptual biases had been corrected for successfully. We discuss the implications on the information-based regulation of hand movement of our finding that the angle-of-approach effect in lateral

  2. Effect of integral membrane proteins on the lateral mobility of plastoquinone in phosphatidylcholine proteoliposomes

    PubMed Central

    Blackwell, Mary F.; Whitmarsh, John

    1990-01-01

    Pyrene fluorescence quenching by plastoquinone was used to estimate the rate of plastoquinone lateral diffusion in soybean phosphatidylcholine proteoliposomes containing the following integral membrane proteins: gramicidin D, spinach cytochrome bf complex, spinach cytochrome f, reaction centers from Rhodobacter sphaeroides, beef heart mitochondrial cytochrome bc1, and beef heart mitochondrial cytochrome oxidase. The measured plastoquinone lateral diffusion coefficient varied between 1 and 3 · 10-7 cm2 s-1 in control liposomes that lacked protein. When proteins were added, these values decreased: a 10-fold decrease was observed when 16-26% of the membrane surface area was occupied by protein for all the proteins but gramicidin. The larger protein complexes (cytochrome bf, Rhodobacter sphaeroides reaction centers, cytochrome bc1, and cytochrome oxidase), whose hydrophobic volumes were 15-20 times as large as that of cytochrome f and the gramicidin transmembrane dimer, were 15-20 times as effective in decreasing the lateral-diffusion coefficient over the range of concentrations studied. These proteins had a much stronger effect than that observed for bacteriorhodopsin in fluorescence photobleaching recovery measurements. The effect of high-protein concentrations in gramicidin proteoliposomes was in close agreement with fluorescence photobleaching measurements. The results are compared with the predictions of several theoretical models of lateral mobility as a function of integral membrane concentration. PMID:19431774

  3. Simulation of synergistic effects on lateral PNP bipolar transistors induced by neutron and gamma irradiation

    NASA Astrophysics Data System (ADS)

    Wang, Chenhui; Bai, Xiaoyan; Chen, Wei; Yang, Shanchao; Liu, Yan; Jin, Xiaoming; Ding, Lili

    2015-10-01

    With semiconductor device simulation software TCAD, numerical simulations of ionizing/displacement synergistic effects on 6 kinds of lateral PNP bipolar transistors induced by the mixed irradiation of neutron and gamma are carried out by means of changing the minority carrier lifetimes, adding charged traps to the oxide layer and increasing the surface recombination velocity in Si/SiO2 interface. The results indicate that ionizing/displacement synergistic effects on the lateral PNP bipolar transistors are not a simple sum of total ionizing dose effects and displacement effects, and total ionizing dose effects can enhance neutron displacement damages, leading to greater gain degradation. The physical mechanisms of ionizing/displacement synergistic effects are analyzed based on the results. The positive charge in the oxide layer and Si/SiO2 interface traps induced by gamma irradiation can enhance the recombination processes of carriers in the bulk defects induced by neutron irradiation, and this is the main cause of ionizing/displacement synergistic effects on the lateral PNP bipolar transistors.

  4. Cost-effective flat-plate photovoltaic modules using light trapping. Final report

    SciTech Connect

    Bain, C.N.; Gordon, B.A.; Knasel, T.M.; Malinowski, R.L.

    1981-04-01

    Work in optical trapping in thick films is extended to form a design guide for photovoltaic engineers. Details of the methods, techniques, and considerations that are used in the definition and analysis of light trapping photovoltaic panels are provided. Assumptions, sources of data, optical and cost modeling methods and the techniques used in the analysis are included. The ways to use light trapping are discussed, and methods are described to use simplified design and costing equations to predict performance and cost benefits. Four significant ways to use the findings presented are: a minimum design change module; an optimum packing factor module concept; roof or wall integrated panels; and modules using light trapping from cell grids. Finally, a design guide is included which shows how to construct photovoltaic modules to exploit light trapping. It is claimed that up to 20% improvements in standard module performance can be expected. (LEW)

  5. [Effects of Vitamin B12 in Patients with Amyotrophic Lateral Sclerosis and Peripheral Neuropathy].

    PubMed

    Nodera, Hiroyuki; Izumi, Yuishin; Kaji, Ryuji

    2015-09-01

    Vitamin B(12)(vB(12)) deficient is regarded as iatrogenic in some cases. Although the recommended oral intake of vB(12) has been determined, administration of vB(12) exceeding the recommended dose could have multiple pharmacological effects. "Ultra-high dose" vB(12) therapy has been used for peripheral neuropathy and amyotrophic lateral sclerosis, suggesting its promising neuroprotective effects. PMID:26329154

  6. Effects of exciplex on the electroluminescent and photovoltaic properties of organic diodes based on terbium complex

    NASA Astrophysics Data System (ADS)

    He, Hong; Li, Wenlian; Su, Zisheng; Li, Tianle; Su, Wenming; Chu, Bei; Bi, Defeng; Han, Liangliang; Wang, Dan; Chen, Lili; Li, Bin; Zhang, Zhiqiang; Hu, ZhiZhi

    2008-01-01

    We fabricated two organic diodes, one of which consists of a double layer structure of TPD/Tb(ACA) 3phen and in the other one a mixture layer is inserted between the double layer, i.e., TPD/TPD:Tb(ACA) 3phen (1:1, 30 nm)/Tb(ACA) 3phen, here TPD and Tb(ACA) 3phen are ( N, N'-diphenyl- N, N'-bis(3-methyl-phenyl)-1,1'-biphenyl-4,4'-diamine) and tris(acetylacetonato)-(mono-phenothroline) terbium, respectively. Both the devices show electroluminescence (EL) properties under forward bias and photovoltaic (PV) effects under illumination of ultraviolet (UV) light. For the device with a mixture layer, the EL performance and PV effects were both significantly improved. A maximum EL brightness of 150 cd/m 2 under bias of 17 V and a maximum efficiency of 1.1 cd/A at 7.5 V were obtained. Moreover, the diode shows a short-circuit current ( Isc) of 43 μA cm -2, an open-circuit voltage ( Voc) of 1.1 V, a fill factor (FF) of 0.32, and an overall power conversion efficiency ( ηPV) of 1.0% under illumination of 365 nm UV light with 1.5 mW/cm 2. The improvements of PV- and EL-properties were presumably attributed to the increased intermolecular contacts in the mixture of TPD and Tb-complex. In addition, a shift of EL color from UV-blue to green-yellow was also observed when a mixture layer of TPD with Tb-complex was inserted. The operation mechanisms of the EL- and the PV-processes of the diodes with different structures were further discussed.

  7. Ultrafast charge-transfer in organic photovoltaic interfaces: geometrical and functionalization effects.

    PubMed

    Santos, Elton J G; Wang, W L

    2016-09-21

    Understanding the microscopic mechanisms of electronic excitation in organic photovoltaic cells is a challenging problem in the design of efficient devices capable of performing sunlight harvesting. Here we develop and apply an ab initio approach based on time-dependent density functional theory and Ehrenfest dynamics to investigate photoinduced charge transfer in small organic molecules. Our calculations include mixed quantum-classical dynamics with ions moving classically and electrons quantum mechanically, where no experimental external parameter other than the material geometry is required. We show that the behavior of photocarriers in zinc phthalocyanine (ZnPc) and C60 systems, an effective prototype system for organic solar cells, is sensitive to the atomic orientation of the donor and the acceptor units as well as the functionalization of covalent molecules at the interface. In particular, configurations with the ZnPc molecules facing on C60 facilitate charge transfer between substrate and molecules that occurs within 200 fs. In contrast, configurations where ZnPc is tilted above C60 present extremely low carrier injection efficiency even at longer times as an effect of the larger interfacial potential level offset and higher energetic barrier between the donor and acceptor molecules. An enhancement of charge injection into C60 at shorter times is observed as binding groups connect ZnPc and C60 in a dyad system. Our results demonstrate a promising way of designing and controlling photoinduced charge transfer on the atomic level in organic devices that would lead to efficient carrier separation and maximize device performance. PMID:27314747

  8. Effect of UV aging on degradation of Ethylene-vinyl Acetate (EVA) as encapsulant in photovoltaic (PV) modules

    NASA Astrophysics Data System (ADS)

    Badiee, Amir; Wildman, Ricky; Ashcroft, Ian

    2014-10-01

    A lifetime of 20-30 years is generally regarded as necessary for photovoltaic modules to achieve economic break even. As a consequence, understanding how to improve the durability and reliability of the modules is becoming a necessity. Photovoltaic modules are exposed to extremely harsh conditions of heat, humidity, and ultraviolet (UV) radiation which affect the properties of the encapsulant material and cause yellowing, delamination and degradation of the material, which knock on effects on the performance and the long-term reliability of photovoltaic modules. This study addresses the impact of UV on the photochemical degradation of Ethylene-vinyl Acetate (EVA). Fourier Transform Infrared Spectroscopy in Attenuated Total Reflectance (FTIR-ATR) mode was performed on aged samples. The samples were exposed to UV light from a xenon lamp at 0.68 W/m2 at 340 nm with exposure up to 1000 hours. The FTIR-ATR measurement shows significant changes in the absorption at 1740 cm-1, 1720 cm-1 and 910 cm-1 which correspond to acetate, carboxylic acid and vinyl group respectively. It is shown that the UV exposure is the most significant aging factor. The rate of the photooxidation of EVA is compared by measuring the changes of absorbance at 1720 cm-1 with the UV irradiation time.

  9. An Experimental Study on Pile Spacing Effects under Lateral Loading in Sand

    PubMed Central

    Khari, Mahdy; Kassim, Khairul Anuar; Adnan, Azlan

    2013-01-01

    Grouped and single pile behavior differs owing to the impacts of the pile-to-pile interaction. Ultimate lateral resistance and lateral subgrade modulus within a pile group are known as the key parameters in the soil-pile interaction phenomenon. In this study, a series of experimental investigation was carried out on single and group pile subjected to monotonic lateral loadings. Experimental investigations were conducted on twelve model pile groups of configurations 1 × 2, 1 × 3, 2 × 2, 3 × 3, and 3 × 2 for embedded length-to-diameter ratio l/d = 32 into loose and dense sand, spacing from 3 to 6 pile diameter, in parallel and series arrangement. The tests were performed in dry sand from Johor Bahru, Malaysia. To reconstruct the sand samples, the new designed apparatus, Mobile Pluviator, was adopted. The ultimate lateral load is increased 53% in increasing of s/d from 3 to 6 owing to effects of sand relative density. An increasing of the number of piles in-group decreases the group efficiency owing to the increasing of overlapped stress zones and active wedges. A ratio of s/d more than 6d is large enough to eliminate the pile-to-pile interaction and the group effects. It may be more in the loose sand. PMID:24453900

  10. An experimental study on pile spacing effects under lateral loading in sand.

    PubMed

    Khari, Mahdy; Kassim, Khairul Anuar; Adnan, Azlan

    2013-01-01

    Grouped and single pile behavior differs owing to the impacts of the pile-to-pile interaction. Ultimate lateral resistance and lateral subgrade modulus within a pile group are known as the key parameters in the soil-pile interaction phenomenon. In this study, a series of experimental investigation was carried out on single and group pile subjected to monotonic lateral loadings. Experimental investigations were conducted on twelve model pile groups of configurations 1 × 2, 1 × 3, 2 × 2, 3 × 3, and 3 × 2 for embedded length-to-diameter ratio l/d = 32 into loose and dense sand, spacing from 3 to 6 pile diameter, in parallel and series arrangement. The tests were performed in dry sand from Johor Bahru, Malaysia. To reconstruct the sand samples, the new designed apparatus, Mobile Pluviator, was adopted. The ultimate lateral load is increased 53% in increasing of s/d from 3 to 6 owing to effects of sand relative density. An increasing of the number of piles in-group decreases the group efficiency owing to the increasing of overlapped stress zones and active wedges. A ratio of s/d more than 6d is large enough to eliminate the pile-to-pile interaction and the group effects. It may be more in the loose sand. PMID:24453900

  11. Lateral tip control effects in CD-AFM metrology: the large tip limit

    NASA Astrophysics Data System (ADS)

    Dixson, Ronald; Goldband, Ryan S.; Orji, Ndubuisi G.

    2015-10-01

    Critical dimension atomic force microscopes (CD-AFMs) use flared tips and two-dimensional sensing and control of the tip-sample interaction to enable scanning of features with near-vertical or even reentrant sidewalls. Sidewall sensing in CD-AFM usually involves lateral dither of the tip, which was the case in the first two generations of instruments. Current, third generation instruments also utilize a control algorithm and fast response piezo actuator to position the tip in a manner that resembles touch-triggering of coordinate measuring machine (CMM) probes. All methods of tip position control, however, induce an effective tip width that may deviate from the actual geometrical tip width. The National Institute of Standards and Technology (NIST) has been investigating the dependence of effective tip width on the dither settings and lateral stiffness of the tip, as well as the possibility of material effects due to sample composition. We have concluded that these effects will not generally result in a residual bias, provided that the tip calibration and sample measurement are performed under the same conditions. To further validate our prior conclusions about the dependence of effective tip width on lateral stiffness, we recently performed experiments using a very large non-CD tip with an etched plateau of approximately 2 μm width. The effective lateral stiffness of these tips is at least 20 times greater than typical CD-AFM tips, and these results supported our prior conclusions about the expected behavior for larger tips. The bottom-line importance of these latest observations is that we can now reasonably conclude that a dither slope of 3 nm/V is the baseline response due to the induced motion of the cantilever base.

  12. Photoconductive and photovoltaic response of high-dark-resistivity 6H-SiC devices

    NASA Technical Reports Server (NTRS)

    Cho, Pak S.; Goldhar, Julius; Lee, Chi H.; Saddow, Stephen E.; Neudeck, Philip

    1995-01-01

    The optoelectronic properties of high-resistivity p-type hexagonal silicon carbide (6H-SiC) have been investigated using lateral photoconductive switches. Both photovoltaic and photoconductive effects are reported, measured at 337 nm, which is above the 6H-SiC absorption edge. These photoconductive switches have been fabricated with dark resistances of up to 1 M omega; photoconductive switching efficiencies of more than 80% have been achieved. In addition, these devices displayed a high-speed photovoltaic response to nanosecond laser excitations in the ultraviolet spectral region; in particular, the observed photovoltaic response pulse width can be shorter than the exciting laser pulse width. This subnanosecond photovoltaic response has been modeled and good qualitative agreement with experiment has been obtained.

  13. Effects of an Auditory Lateralization Training in Children Suspected to Central Auditory Processing Disorder

    PubMed Central

    Lotfi, Yones; Moosavi, Abdollah; Bakhshi, Enayatollah; Sadjedi, Hamed

    2016-01-01

    Background and Objectives Central auditory processing disorder [(C)APD] refers to a deficit in auditory stimuli processing in nervous system that is not due to higher-order language or cognitive factors. One of the problems in children with (C)APD is spatial difficulties which have been overlooked despite their significance. Localization is an auditory ability to detect sound sources in space and can help to differentiate between the desired speech from other simultaneous sound sources. Aim of this research was investigating effects of an auditory lateralization training on speech perception in presence of noise/competing signals in children suspected to (C)APD. Subjects and Methods In this analytical interventional study, 60 children suspected to (C)APD were selected based on multiple auditory processing assessment subtests. They were randomly divided into two groups: control (mean age 9.07) and training groups (mean age 9.00). Training program consisted of detection and pointing to sound sources delivered with interaural time differences under headphones for 12 formal sessions (6 weeks). Spatial word recognition score (WRS) and monaural selective auditory attention test (mSAAT) were used to follow the auditory lateralization training effects. Results This study showed that in the training group, mSAAT score and spatial WRS in noise (p value≤0.001) improved significantly after the auditory lateralization training. Conclusions We used auditory lateralization training for 6 weeks and showed that auditory lateralization can improve speech understanding in noise significantly. The generalization of this results needs further researches. PMID:27626084

  14. Effect of scanning beam size on the lateral resolution of mouse retinal imaging with SLO

    PubMed Central

    Zhang, Pengfei; Goswami, Mayank; Zam, Azhar; Pugh, Edward N.; Zawadzki, Robert J.

    2016-01-01

    Scanning laser ophthalmoscopy (SLO) employs the eye’s optics as a microscope objective for retinal imaging in vivo. The mouse retina has become an increasingly important object for investigation of ocular disease and physiology with optogenetic probes. SLO imaging of the mouse eye, in principle, can achieve submicron lateral resolution thanks to a numerical aperture (NA) of ~0.5, about 2.5 times larger than that of the human eye. In the absence of adaptive optics, however, natural ocular aberrations limit the available optical resolution. The use of a contact lens, in principle, can correct many aberrations, permitting the use of a wider scanning beam and, thus, achieving greater resolution then would otherwise be possible. In this Letter, using an SLO equipped with a rigid contact lens, we report the effect of scanning beam size on the lateral resolution of mouse retinal imaging. Theory predicts that the maximum beam size full width at half-maximum (FWHM) that can be used without any deteriorating effects of aberrations is ~0.6 mm. However, increasing the beam size up to the diameter of the dilated pupil is predicted to improve lateral resolution, though not to the diffraction limit. To test these predictions, the dendrites of a retinal ganglion cell expressing YFP were imaged, and transverse scans were analyzed to quantify the SLO system resolution. The results confirmed that lateral resolution increases with the beam size as predicted. With a 1.3 mm scanning beam and no high-order aberration correction, the lateral resolution is ~1.15 μm, superior to that achievable by most human AO-SLO systems. Advantages of this approach include stabilization of the mouse eye and simplified optical design. PMID:26670523

  15. Effects of piping irrigation laterals on selenium and salt loads, Montrose Arroyo Basin, western Colorado

    USGS Publications Warehouse

    Butler, D.L.

    2001-01-01

    Selenium and salinity are water-quality issues in the Upper Colorado River Basin. Certain water bodies in the lower Gunnison River Basin, including the lower Gunnison River and the Uncompahgre River, exceed the State standard for selenium of 5 micrograms per liter. Remediation methods to reduce selenium and salt loading in the lower Gunnison River Basin were examined. A demonstration project in Montrose Arroyo, located in the Uncompahgre River Basin near Montrose, was done during 1998-2000 to determine the effects on selenium and salt loads in Montrose Arroyo from replacing 8.5 miles of open-ditch irrigation laterals with 7.5 miles of pipe. The participants in the project were the National Irrigation Water Quality Program, the Colorado River Basin Salinity Control Program, the Uncompahgre Valley Water Users Association, and the U.S. Geological Survey. The placing of five laterals in pipe significantly decreased selenium loads in Montrose Arroyo. The selenium load at the outflow monitoring site was about 194 pounds per year less (28-percent decrease) in the period after the laterals were placed in pipe. More than 90 percent of the decrease in selenium load was attributed to a decrease in ground-water load. Salt loads also decreased because of the lateral project, but by a smaller percentage than the selenium loads. The salt load at the outflow site on Montrose Arroyo was about 1,980 tons per year less in the post-project period than in the pre-project period. All of the effects of the demonstration project on selenium and salt loads probably were not measured by this study because some of the lateral leakage that was eliminated had not necessarily discharged to Montrose Arroyo upstream from the monitoring sites. A greater decrease in selenium loads relative to salt loads may have been partially the result of decreases in selenium concentrations in ground water in some areas.

  16. Effect of scanning beam size on the lateral resolution of mouse retinal imaging with SLO.

    PubMed

    Zhang, Pengfei; Goswami, Mayank; Zam, Azhar; Pugh, Edward N; Zawadzki, Robert J

    2015-12-15

    Scanning laser ophthalmoscopy (SLO) employs the eye's optics as a microscope objective for retinal imaging in vivo. The mouse retina has become an increasingly important object for investigation of ocular disease and physiology with optogenetic probes. SLO imaging of the mouse eye, in principle, can achieve submicron lateral resolution thanks to a numerical aperture (NA) of ∼0.5, about 2.5 times larger than that of the human eye. In the absence of adaptive optics, however, natural ocular aberrations limit the available optical resolution. The use of a contact lens, in principle, can correct many aberrations, permitting the use of a wider scanning beam and, thus, achieving greater resolution then would otherwise be possible. In this Letter, using an SLO equipped with a rigid contact lens, we report the effect of scanning beam size on the lateral resolution of mouse retinal imaging. Theory predicts that the maximum beam size full width at half-maximum (FWHM) that can be used without any deteriorating effects of aberrations is ∼0.6  mm. However, increasing the beam size up to the diameter of the dilated pupil is predicted to improve lateral resolution, though not to the diffraction limit. To test these predictions, the dendrites of a retinal ganglion cell expressing YFP were imaged, and transverse scans were analyzed to quantify the SLO system resolution. The results confirmed that lateral resolution increases with the beam size as predicted. With a 1.3 mm scanning beam and no high-order aberration correction, the lateral resolution is ∼1.15  μm, superior to that achievable by most human AO-SLO systems. Advantages of this approach include stabilization of the mouse eye and simplified optical design. PMID:26670523

  17. An investigation of the effect of wind cooling on photovoltaic arrays

    NASA Technical Reports Server (NTRS)

    Wen, L.

    1982-01-01

    Convective cooling of photovoltaic modules for different wind conditions, including steady state controlled testing in a solar simulator and natural test environments in a field was investigated. Analytical thermal models of different module designs were used to correlate experimental data. The applicability of existing heat transfer correlations is confirmed. Reasonable agreement is obtained by applying a power law wind profile.

  18. Valence specific laterality effects in free viewing conditions: the role of expectancy and gender of image.

    PubMed

    Stafford, Lorenzo D; Brandaro, Nicola

    2010-12-01

    Recent research has looked at whether the expectancy of an emotion can account for subsequent valence specific laterality effects of prosodic emotion, though no research has examined this effect for facial emotion. In the study here (n=58), we investigated this issue using two tasks; an emotional face perception task and a novel word task that involved categorising positive and negative words. In the face perception task a valence specific laterality effect was found for surprise (positive) and anger (negative) faces in the control but not expectancy condition. Interestingly, lateralisation differed for face gender, revealing a left hemisphere advantage for male faces and a right hemisphere advantage for female faces. In the word task, an affective priming effect was found, with higher accuracy when valence of picture prime and word target were congruent. Target words were also responded to faster when presented to the LVF versus RVF in the expectancy but not control condition. These findings suggest that expecting an emotion influences laterality processing but that this differs in terms of the perceptual/experience dimension of the task. Further, that hemispheric processing of emotional expressions appear to differ in the gender of the image. PMID:20934796

  19. Photovoltaic effect and enhanced magnetization in 0.9(BiFeO3)-0.1(YCrO3) composite thin film fabricated using sequential pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Sharma, Yogesh; Misra, Pankaj; Katiyar, Rajesh K.; Katiyar, Ram S.

    2014-10-01

    We report on the photovoltaic effect and multiferroic properties of a 0.9(BiFeO3)-0.1(YCrO3) composite thin film deposited on a Pt/TiO2/SiO2/Si substrate by sequential ablation of BiFeO3 and YCrO3 ceramic targets using pulsed laser deposition. The desired composition of the composite was achieved by controlling the ablation time of respective targets. As confirmed by the x-ray diffraction pattern the resultant film was found to be polycrystalline in nature and composed of a mixture of both rhombohedral BiFeO3 and orthorhombic YCrO3 phases. Interesting multiferroic properties in terms of an enhanced saturation magnetization of ˜14 emu cm-3 and the remnant polarization of ˜4.5 µC cm-2 were observed where the enhancement in magnetization as compared to pristine BiFeO3 could be attributed to the super-exchange interaction between Fe and Cr-ions. The photovoltaic properties of the composite thin film were studied under white light illumination in both top-bottom and lateral electrode configurations. Short circuit current densities (JSC) = 1.48 µA cm-2 and 0.44 µA cm-2, and open circuit voltages (VOC) = 0.51 V and 0.32 V were observed in top-bottom and lateral electrode configurations, respectively.

  20. Effects of lateral asymmetry on electronic structure of strained semiconductor nanorings in a magnetic field

    NASA Astrophysics Data System (ADS)

    Milošević, M. M.; Tadić, M.; Peeters, F. M.

    2008-11-01

    The influence of lateral asymmetry on the electronic structure and optical transitions in elliptical strained InAs nanorings is analyzed in the presence of a perpendicular magnetic field. Two-dimensional rings are assumed to have elliptical inner and outer boundaries oriented in mutually orthogonal directions. The influence of the eccentricity of the ring on the energy levels is analyzed. For large eccentricity of the ring, we do not find any Aharonov-Bohm effect, in contrast to circular rings. Rather, the single-particle states of the electrons and the holes are localized as in two laterally coupled quantum dots formed in the lobes of the nanoring. Our work indicates that the control of shape is important for the existence of the Aharonov-Bohm effect in semiconductor nanorings.

  1. Effects of lateral asymmetry on electronic structure of strained semiconductor nanorings in a magnetic field.

    PubMed

    Milošević, M M; Tadić, M; Peeters, F M

    2008-11-12

    The influence of lateral asymmetry on the electronic structure and optical transitions in elliptical strained InAs nanorings is analyzed in the presence of a perpendicular magnetic field. Two-dimensional rings are assumed to have elliptical inner and outer boundaries oriented in mutually orthogonal directions. The influence of the eccentricity of the ring on the energy levels is analyzed. For large eccentricity of the ring, we do not find any Aharonov-Bohm effect, in contrast to circular rings. Rather, the single-particle states of the electrons and the holes are localized as in two laterally coupled quantum dots formed in the lobes of the nanoring. Our work indicates that the control of shape is important for the existence of the Aharonov-Bohm effect in semiconductor nanorings. PMID:21832775

  2. Effect of cholesterol on the lateral nanoscale dynamics of fluid membranes

    SciTech Connect

    Armstrong, Clare L; Barrett, M; Heiss, Arno; Salditt, Tim; Katsaras, John; Shi, An-Chang; Rheinstadter, Maikel C

    2012-01-01

    Inelastic neutron scattering was used to study the effect of 5 and 40 mol% cholesterol on the lateral nanoscale dynamics of phospholipid membranes. By measuring the excitation spectrum at several lateral q || values (up to q || = 3 1), complete dispersion curves were determined of gel, fluid and liquid-ordered phase bilayers. The inclusion of cholesterol had a distinct effect on the collective dynamics of the bilayer s hydrocarbon chains; specifically, we observed a pronounced stiffening of the membranes on the nanometer length scale in both gel and fluid bilayers, even though they were experiencing a higher degree of molecular disorder. Also, for the first time we determined the nanoscale dynamics in the high-cholesterol liquid-ordered phase of bilayers containing cholesterol. Namely, this phase appears to be softer than fluid bilayers, but better ordered than bilayers in the gel phase.

  3. Photovoltaic Engineering

    NASA Technical Reports Server (NTRS)

    2005-01-01

    The Ohio Aerospace Institute through David Scheiman and Phillip Jenkins provided the Photovoltaics Branch at the NASA Glenn Research Center (GRC) with expertise in photovoltaic (PV) research, flight experiments and solar cell calibration. NASA GRC maintains the only world-class solar cell calibration and measurement facility within NASA. GRC also has a leadership role within the solar cell calibration community, and is leading the effort to develop ISO standards for solar cell calibration. OAI scientists working under this grant provided much of the expertise and leadership in this area.

  4. Optimal velocity model with consideration of the lateral effect and its feedback control research

    NASA Astrophysics Data System (ADS)

    Zheng, Y. Z.; Ge, H. X.

    2016-06-01

    In this paper, a car-following model with the consideration of lateral effect is constructed. An improved control signal with considering more comprehensive information is introduced according to the feedback control theory. The stability conditions with control signal or not are derived. Numerical simulations are carried out to illustrate the advantage of the modified model with and without the control signal, and the results are consistent with the analytical ones.

  5. Geometric dephasing-limited Hanle effect in long-distance lateral silicon spin transport devices

    NASA Astrophysics Data System (ADS)

    Huang, Biqin; Jang, Hyuk-Jae; Appelbaum, Ian

    2008-10-01

    Evidence of spin precession and dephasing ("Hanle effect") induced by a magnetic field is the only unequivocal proof of spin-polarized conduction electron transport in semiconductor devices. However, when spin dephasing is very strong, Hanle effect in a uniaxial magnetic field can be impossible to measure. Using a silicon device with lateral injector-detector separation of over 2 mm and geometrically induced dephasing making spin transport completely incoherent, we show experimentally and theoretically that Hanle effect can still be measured using a two-axis magnetic field.

  6. Photovoltaic concentrator research progress

    SciTech Connect

    Arvizu, D.E.

    1985-01-01

    This paper provides a review of progress in the DOE sponsored, Sandia managed Photovoltaic Concentrator Research Project. Research status, project goals and a discussion of concentrator economics is presented. Recent research accomplishments that will be discussed include 21% efficient baseline silicon cells by Applied Solar Energy Corporation and Sandia, 26% efficient GaAs cells by Varian Associates, and near 25% mechanically stacked multijunction GaAs/Si cells by Hughes Research, Applied Solar, and Sandia. In addition, improvements in breadboard module units (i.e. single lens/cell combination) such as a 19% GaAs unit by Varian and a near 17% silicon unit by ENTECH will be reviewed. This paper concludes that the photovoltaic concentrator option is making excellent progress toward competitive cost-effectiveness and provides a strong photovoltaic alternative.

  7. Isolation and Genetic Characterization of Mother-of-Snow-White, a Maternal Effect Allele Affecting Laterality and Lateralized Behaviors in Zebrafish

    PubMed Central

    Domenichini, Alice; Dadda, Marco; Facchin, Lucilla; Bisazza, Angelo; Argenton, Francesco

    2011-01-01

    In the present work we report evidence compatible with a maternal effect allele affecting left-right development and functional lateralization in vertebrates. Our study demonstrates that the increased frequency of reversed brain asymmetries in a zebrafish line isolated through a behavioral assay is due to selection of mother-of-snow-white (msw), a maternal effect allele involved in early stages of left-right development in zebrafish. msw homozygous females could be identified by screening of their progeny for the position of the parapineal organ because in about 50% of their offspring we found an altered, either bilateral or right-sided, expression of lefty1 and spaw. Deeper investigations at earlier stages of development revealed that msw is involved in the specification and differentiation of precursors of the Kupffer's vesicle, a structure homologous to the mammalian node. To test the hypothesis that msw, by controlling Kupffer's vesicle morphogenesis, controls lateralized behaviors related to diencephalic asymmetries, we analyzed left- and right-parapineal offspring in a “viewing test”. As a result, left- and right-parapineal individuals showed opposite and complementary eye preference when scrutinizing a model predator, and a different degree of lateralization when scrutinizing a virtual companion. As maternal effect genes are expected to evolve more rapidly when compared to zygotic ones, our results highlight the driving force of maternal effect alleles in the evolution of vertebrates behaviors. PMID:22022484

  8. Photovoltaic cell

    SciTech Connect

    Bronstein-Bonte, I.Y.; Fischer, A.B.

    1986-12-16

    This patent describes a product comprising a photovoltaic cell including a luminescent dye which will absorb radiation at a wavelength to which the cell is not significantly responsive and emit radiation at a higher wavelength at which it is responsive. The improvement described here is wherein the dye comprises a lepidopterene.

  9. Photovoltaic energy

    NASA Astrophysics Data System (ADS)

    1990-01-01

    In 1989, the U.S. photovoltaic industry enjoyed a growth rate of 30 percent in sales for the second year in a row. This sends a message that the way we think about electricity is changing. Instead of big energy projects that perpetuate environmental and economic damage, there is a growing trend toward small renewable technologies that are well matched to end-user needs and operating conditions. As demand grows and markets expand, investment capital will be drawn to the industry and new growth trends will emerge. The photovoltaic industry around the world achieved record shipments also. Worldwide shipments of photovoltaic (PV) modules for 1989 totaled more than 40 megawatts (MW), nearly a 20 percent increase over last year's shipments. The previous two years showed increases in worldwide shipments of 23 and 25 percent, respectively. If this growth rate continues through the 1990s, as industry back orders would indicate, 300 to 1000 MW of PV-supplied power could be on line by 2000. Photovoltaic systems have low environmental impact and they are inexpensive to operate and maintain. Using solid-state technology, PV systems directly convert sunlight to electricity without high-temperature fluids or moving parts that could cause mechanical failure. This makes the technology very reliable.

  10. Estimating the influence of life satisfaction and positive affect on later income using sibling fixed effects

    PubMed Central

    De Neve, Jan-Emmanuel; Oswald, Andrew J.

    2012-01-01

    The question of whether there is a connection between income and psychological well-being is a long-studied issue across the social, psychological, and behavioral sciences. Much research has found that richer people tend to be happier. However, relatively little attention has been paid to whether happier individuals perform better financially in the first place. This possibility of reverse causality is arguably understudied. Using data from a large US representative panel, we show that adolescents and young adults who report higher life satisfaction or positive affect grow up to earn significantly higher levels of income later in life. We focus on earnings approximately one decade after the person’s well-being is measured; we exploit the availability of sibling clusters to introduce family fixed effects; we account for the human capacity to imagine later socioeconomic outcomes and to anticipate the resulting feelings in current well-being. The study’s results are robust to the inclusion of controls such as education, intelligence quotient, physical health, height, self-esteem, and later happiness. We consider how psychological well-being may influence income. Sobel–Goodman mediation tests reveal direct and indirect effects that carry the influence from happiness to income. Significant mediating pathways include a higher probability of obtaining a college degree, getting hired and promoted, having higher degrees of optimism and extraversion, and less neuroticism. PMID:23169627

  11. Alternate models of sibling status effects on health in later life.

    PubMed

    Falbo, Toni; Kim, Sunghun; Chen, Kuan-Yi

    2009-05-01

    Although siblings are thought to be influential in child development, little is known about the influence of sibling status on the health of older adults. Using structural equation modeling, the authors created and tested a series of models with data from a sample (N = 3,968) of 1957 high school graduates from the Wisconsin Longitudinal Study. The results indicated that socioeconomic status of origin, adolescent aptitude, and educational attainment did have significant total effects on health in later life, but sibling status did not. Adults who grew up in families of higher socioeconomic status and who had greater aptitude in high school attained more education, and this advantage, in turn, led to better health in later life. Although the final model was cross-validated, it was not equally plausible for men and women. PMID:19413424

  12. Effect of contact stiffness on wedge calibration of lateral force in atomic force microscopy

    SciTech Connect

    Wang Fei; Zhao Xuezeng

    2007-04-15

    Quantitative friction measurement of nanomaterials in atomic force microscope requires accurate calibration method for lateral force. The effect of contact stiffness on lateral force calibration of atomic force microscope is discussed in detail and an improved calibration method is presented. The calibration factor derived from the original method increased with the applied normal load, which indicates that separate calibration should be required for every given applied normal load to keep the accuracy of friction measurement. We improve the original method by introducing the contact factor, which is derived from the contact stiffness between the tip and the sample, to the calculation of calibration factors. The improved method makes the calculation of calibration factors under different applied normal loads possible without repeating the calibration procedure. Comparative experiments on a silicon wafer have been done by both the two methods to validate the method in this article.

  13. Lateral conduction effects on heat-transfer data obtained with the phase-change paint technique

    NASA Technical Reports Server (NTRS)

    Maise, G.; Rossi, M. J.

    1974-01-01

    A computerized tool, CAPE, (Conduction Analysis Program using Eigenvalues) has been developed to account for lateral heat conduction in wind tunnel models in the data reduction of the phase-change paint technique. The tool also accounts for the effects of finite thickness (thin wings) and surface curvature. A special reduction procedure using just one time of melt is also possible on leading edges. A novel iterative numerical scheme was used, with discretized spatial coordinates but analytic integration in time, to solve the inverse conduction problem involved in the data reduction. A yes-no chart is provided which tells the test engineer when various corrections are large enough so that CAPE should be used. The accuracy of the phase-change paint technique in the presence of finite thickness and lateral conduction is also investigated.

  14. Zero temperature coefficient of resistivity induced by photovoltaic effect in Y Ba2Cu3O6.96 ceramics

    NASA Astrophysics Data System (ADS)

    Yang, Feng; Han, Mengyuan; Chang, Fanggao

    2015-01-01

    I-V characteristics of YBCO-Ag system under blue laser (λ = 450 nm) illumination were studied from 100 to 300 K and obvious photovoltaic effects were observed. All the I-V curves in the temperature range intersect at a point in the first quadrant while the laser points to the cathode electrode, indicating a zero temperature coefficient of resistivity. This implies that the outputting voltage keeps constant in a broad temperature range when a critical bias current is assigned. The intersection points of different laser intensities fall in a straight line, the slope of which (Rc) is independent of temperature and laser intensity.

  15. Static and Dynamic Effects of Lateral Carrier Diffusion in Semiconductor Lasers

    NASA Technical Reports Server (NTRS)

    Li, Jian-Zhong; Cheung, Samson H.; Ning, C. Z.; Biegel, Bryan A. (Technical Monitor)

    2002-01-01

    Electron and hole diffusions in the plane of semiconductor quantum wells play an important part in the static and dynamic operations of semiconductor lasers. It is well known that the value of diffusion coefficients affects the threshold pumping current of a semiconductor laser. At the same time, the strength of carrier diffusion process is expected to affect the modulation bandwidth of an AC-modulated laser. It is important not only to investigate the combined DC and AC effects due to carrier diffusion, but also to separate the AC effects from that of the combined effects in order to provide design insights for high speed modulation. In this presentation, we apply a hydrodynamic model developed by the present authors recently from the semiconductor Bloch equations. The model allows microscopic calculation of the lateral carrier diffusion coefficient, which is a nonlinear function of the carrier density and plasma temperature. We first studied combined AC and DC effects of lateral carrier diffusion by studying the bandwidth dependence on diffusion coefficient at a given DC current under small signal modulation. The results show an increase of modulation bandwidth with decrease in the diffusion coefficient. We simultaneously studied the effects of nonlinearity in the diffusion coefficient. To clearly identify how much of the bandwidth increase is a result of decrease in the threshold pumping current for smaller diffusion coefficient, thus an effective increase of DC pumping, we study the bandwidth dependence on diffusion coefficient at a given relative pumping. A detailed comparison of the two cases will be presented.

  16. Geometric dephasing-limited Hanle effect in long-distance lateral silicon spin transport devices

    NASA Astrophysics Data System (ADS)

    Huang, Biqin; Jang, Hyuk-Jae; Appelbaum, Ian

    2009-03-01

    Using ballistic injection and hot-electron spin filter detection, lateral spin transport over 2 millimeters is demonstrated in undoped single-crystal Silicon. In these devices, geometrically-induced dephasing (Hanle effect) is so strong that the effects of spin precession could not be measured with only a single-axis magnetic field. However, a two-axis magnetic field can be used to obtain unequivocal evidence of spin precession and transport despite full dephasing. We therefore conclude that there is never a reason to avoid measurement of spin precession as unequivocal evidence of spin transport in semiconductor devices.

  17. Effect of diffusion of light on thin-film photovoltaic laminates

    NASA Astrophysics Data System (ADS)

    Mohanty, Lipi; Wittkopf, Stephen K.

    A large fraction of the daylight incident on building-integrated photovoltaic (BIPV) laminates is diffuse irradiance. In this study, fabrics of various weaves were used to simulate combinations of direct and diffuse irradiance on façade-mounted PV. The scattering of light achieved with the fabrics at varying angles of incidence was measured with a goniophotometer. The transmittance distribution was used to quantify the percentage of diffusion created by the fabrics. A photovoltaic (PV) laminate was shaded with the fabrics to simulate diffuse irradiance and the short circuit current of the module was measured. The experimental results indicate fabrics of different porosity can be used to simulate various combinations of direct and diffuse irradiance. However, these fabrics can affect the module output. Preliminary results show that the proximity of the fabric to the thin-film PV laminate during the test skews the measured electrical parameters.

  18. Effect of ZnO:Cs2CO3 on the performance of organic photovoltaics

    PubMed Central

    2014-01-01

    We demonstrate a new solution-processed electron transport layer (ETL), zinc oxide doped with cesium carbonate (ZnO:Cs2CO3), for achieving organic photovoltaics (OPVs) with good operational stability at ambient air. An OPV employing the ZnO:Cs2CO3 ETL exhibits a fill factor of 62%, an open circuit voltage of 0.90 V, and a short circuit current density of −6.14 mA/cm2 along with 3.43% power conversion efficiency. The device demonstrated air stability for a period over 4 weeks. In addition, we also studied the device structure dependence on the performance of organic photovoltaics. Thus, we conclude that ZnO:Cs2CO3 ETL could be employed in a suitable architecture to achieve high-performance OPV. PMID:25045340

  19. Electrochemical and galvanic corrosion effects in thin-film photovoltaic modules

    NASA Astrophysics Data System (ADS)

    Mon, G.; Wen, L.; Meyer, J.; Ross, R., Jr.; Nelson, A.

    The electrochemical and galvanic corrosion properties of thin-film photovoltaic (TF-PV) modules and module subcomponents are determined and interpreted in the light of established corrosion science. Results of a detailed study of thin-film aluminum metallization corrosion are presented. Bar-graph corrosion, observed in fielded modules, has been induced experimentally and found to be electrochemical in nature. Corrosion rates and passivation techniques for TF-PV modules are discussed.

  20. Electrochemical and galvanic corrosion effects in thin-film photovoltaic modules

    NASA Technical Reports Server (NTRS)

    Mon, G.; Wen, L.; Meyer, J.; Ross, R., Jr.; Nelson, A.

    1988-01-01

    The electrochemical and galvanic corrosion properties of thin-film photovoltaic (TF-PV) modules and module subcomponents are determined and interpreted in the light of established corrosion science. Results of a detailed study of thin-film aluminum metallization corrosion are presented. Bar-graph corrosion, observed in fielded modules, has been induced experimentally and found to be electrochemical in nature. Corrosion rates and passivation techniques for TF-PV modules are discussed.

  1. The effect of compensating filter on image quality in lateral projection of thoraco lumbar radiography

    NASA Astrophysics Data System (ADS)

    Daud, N. A. A.; Ali, M. H.; Nazri, N. A. Ahmad; Hamzah, N. J.; Awang, N. A.

    2014-11-01

    The aim of this project was to study the effect of compensating filter on image quality in lateral projection of thoraco lumbar radiography. The specific objectives of this study were to verify the relationship between density, contrast and noise of lateral thoraco lumbar radiography using various thickness of compensating filter and to determine the appropriate filter thickness with the thoraco lumbar density. The study was performed by an X- ray unit exposed to the body phantom where different thicknesses of aluminium were used as compensating filter. The radiographs were processed by CR reader and being imported to KPACS software to analyze the pixel depth value, contrast and noise. Result shows different thickness of aluminium compensating filter improved the image quality of lateral projection thoraco lumbar radiography. The compensating filter of 8.2 mm was considered as the optimal filter to compensate the thoraco lumbar junction (T12-L1), 1 mm to compensate lumbar region and 5.9 mm to compensate thorax region. The addition of aluminium compensating filter is advantageous in terms of efficiency which saving radiograph film, workload of the radiographer and radiation dose to patient.

  2. Gate-tunable diode and photovoltaic effect in an organic-2D layered material p-n junction

    NASA Astrophysics Data System (ADS)

    Vélez, Saül; Ciudad, David; Island, Joshua; Buscema, Michele; Txoperena, Oihana; Parui, Subir; Steele, Gary A.; Casanova, Fèlix; van der Zant, Herre S. J.; Castellanos-Gomez, Andres; Hueso, Luis E.

    2015-09-01

    The semiconducting p-n junction is a simple device structure with great relevance for electronic and optoelectronic applications. The successful integration of low-dimensional materials in electronic circuits has opened the way forward for producing gate-tunable p-n junctions. In that context, we present here an organic (Cu-phthalocyanine)-2D layered material (MoS2) hybrid p-n junction with both gate-tunable diode characteristics and photovoltaic effect. Our proof-of-principle devices show multifunctional properties with diode rectifying factors of up to 104, while under light exposure they exhibit photoresponse with a measured external quantum efficiency of ~11%. As for their photovoltaic properties, we found open circuit voltages of up to 0.6 V and optical-to-electrical power conversion efficiency of 0.7%. The extended catalogue of known organic semiconductors and two-dimensional materials offer the prospect for tailoring the properties and the performance of the resulting devices, making organic-2D p-n junctions promising candidates for future technological applications.The semiconducting p-n junction is a simple device structure with great relevance for electronic and optoelectronic applications. The successful integration of low-dimensional materials in electronic circuits has opened the way forward for producing gate-tunable p-n junctions. In that context, we present here an organic (Cu-phthalocyanine)-2D layered material (MoS2) hybrid p-n junction with both gate-tunable diode characteristics and photovoltaic effect. Our proof-of-principle devices show multifunctional properties with diode rectifying factors of up to 104, while under light exposure they exhibit photoresponse with a measured external quantum efficiency of ~11%. As for their photovoltaic properties, we found open circuit voltages of up to 0.6 V and optical-to-electrical power conversion efficiency of 0.7%. The extended catalogue of known organic semiconductors and two-dimensional materials

  3. Effects of charge carrier concentration in hybrid conjugated polymer/oxide photovoltaic devices

    NASA Astrophysics Data System (ADS)

    White, Matthew Schuette

    2009-12-01

    Organic photovoltaics (OPV) represent an attractive route towards inexpensive, lightweight, and abundant renewable energy. The principal criticisms of OPV are low power conversion efficiency and unstable materials resulting in short device lifetimes. Hybrid OPV (h-OPV) devices with ZnO functioning either as the electron acceptor in the heterojunction, or as an electron transport layer in a polymer/fullerene based heterojunction, present useful device structures for investigating the functional mechanisms within OPV devices and a possible pathway towards air-stable high efficiency devices. Such use allows the vast knowledge surrounding oxide nanostructure morphology, band position, and carrier concentration control to be used in designing bulk-heterojunction OPV devices. The work presented in this thesis explores the effects of carrier concentration modulation in the polymer and/or oxide layers of these devices. Exposure to air is known to induce chemical defects in polymer semiconductors, which act as dopants in OPV devices. This increase in doping density can be used to improve OPV devices, however the low work-function metallic electrodes are often highly air sensitive. Using a silver back electrode and a ZnO interlayer at the transparent front contact in a polymer-based bulk heterojunction device allows for fabrication and testing in air. Relatively efficient devices are fabricated in this manner, but the devices show a characteristic aging time that indicates that air is a requirement to function as a quality diode. Air exposure may be effecting any of the layers in the device, but evidence is presented that shows the increased doping density in the polymer is largely responsible for the change in device quality over this time period. When oxides are used as the electron acceptor material in the device heterojunction, the carrier concentration in both the oxide and the polymer determine the strength of the electric field at the junction. Oxygen related doping

  4. Ultrafast Lateral Photo-Dember Effect in Graphene Induced by Nonequilibrium Hot Carrier Dynamics.

    PubMed

    Liu, Chang-Hua; Chang, You-Chia; Lee, Seunghyun; Zhang, Yaozhong; Zhang, Yafei; Norris, Theodore B; Zhong, Zhaohui

    2015-06-10

    The photo-Dember effect arises from the asymmetric diffusivity of photoexcited electrons and holes, which creates a transient spatial charge distribution and hence the buildup of a voltage. Conventionally, a strong photo-Dember effect is only observed in semiconductors with a large asymmetry between the electron and hole mobilities, such as in GaAs or InAs, and is considered negligible in graphene due to its electron-hole symmetry. Here, we report the observation of a strong lateral photo-Dember effect induced by nonequilibrium hot carrier dynamics when exciting a graphene-metal interface with a femtosecond laser. Scanning photocurrent measurements reveal the extraction of photoexcited hot carriers is driven by the transient photo-Dember field, and the polarity of the photocurrent is determined by the device's mobility asymmetry. Furthermore, ultrafast pump-probe measurements indicate the magnitude of photocurrent is related to the hot carrier cooling rate. Our simulations also suggest that the lateral photo-Dember effect originates from graphene's 2D nature combined with its unique electrical and optical properties. Taken together, these results not only reveal a new ultrafast photocurrent generation mechanism in graphene but also suggest new types of terahertz sources based on 2D nanomaterials. PMID:25993273

  5. Word and pseudoword superiority effects in a shallow orthography language: the role of hemispheric lateralization.

    PubMed

    Ripamonti, Enrico; Traficante, Daniela; Crippa, Franca; Luzzattii, Claudio

    2014-04-01

    The word superiority effect (WSE) has made it possible to demonstrate the automatic activation of lexical-orthographic entries in reading. The observation of this effect is important since it led to experimental support of the main cognitive reading models. These models were mostly developed on English data, hence the verification in different orthography systems is relevant. The present study tested WSE in Italian, a language in which this effect was predicted to be less constant given the highly consistent correspondence between orthography and phonology. Moreover, the presentation of the items in a lateralized visual field condition allowed testing of assumptions about the roles of the right and left hemispheres in written word recognition and, in particular, on the hemispheric lateralization of lexical processing. Two experiments were conducted with undergraduate students who had to recognize a target letter within a word, pseudoword, or nonword. In Experiment 1, prime and probe letters were in the same letter case, while in Experiment 2 they were in different letter cases. Error rates and reaction times were analyzed with mixed models. The results showed a superiority of pseudowords (pseudoword superiority effect; PSE) over illegal strings with no evidence of a clear superiority of words over pseudowords for both left and right visual field presentations. This suggests that in Italian, the sub-lexical route could play a major role in reading and that this route relies on a visual-perceptual orthographic coding concerning familiarity of letter combinations, which is also available to the right hemisphere. PMID:24897877

  6. The effect of oppositional parietal transcranial direct current stimulation on lateralized brain functions.

    PubMed

    Li, Lucia M; Leech, Rob; Scott, Gregory; Malhotra, Paresh; Seemungal, Barry; Sharp, David J

    2015-12-01

    Cognitive functions such as numerical processing and spatial attention show varying degrees of lateralization. Transcranial direct current stimulation (tDCS) can be used to investigate how modulating cortical excitability affects performance of these tasks. This study investigated the effect of bi-parietal tDCS on numerical processing, spatial and sustained attention. It was hypothesized that tDCS would have distinct effects on these tasks because of varying lateralization (numerical processing left, spatial attention right) and that these effects are partly mediated by modulation of sustained attention. A single-blinded, crossover, sham-controlled study was performed. Eighteen healthy right-handed participants performed cognitive tasks during three sessions of oppositional parietal tDCS stimulation: sham; right anodal with left cathodal (RA/LC); and right cathodal with left anodal (RC/LA). Participants performed a number comparison task, a modified Posner task, a choice reaction task (CRT) and the rapid visual processing task (RVP). RA/LC tDCS impaired number comparison performance compared with sham, with slower responses to numerically close numbers pairs. RA/LC and RC/LA tDCS had distinct effects on CRT performance, specifically affecting vigilance level during the final block of the task. No effect of stimulation on the Posner task or RVP was found. It was demonstrated that oppositional parietal tDCS affected both numerical performance and vigilance level in a polarity-dependent manner. The effect of tDCS on numerical processing may partly be due to attentional effects. The behavioural effects of tDCS were specifically observed under high task demands, demonstrating the consequences of an interaction between stimulation type and cognitive load. PMID:26414683

  7. On lateral buckling of end-loaded cantilevers, including the effect of warping stiffness

    NASA Astrophysics Data System (ADS)

    Reissner, E.; Reissner, J. E.; Wan, F. Y. M.

    1987-06-01

    We investigate the numerical consequences of the presence of certain non-linear terms in the expressions for the components of transverse shearing strain which occur in the derivation of one-dimensional equations for small finite deflections of straight beams from three-dimensional finite elasticity through use of the principle of minimum potential energy. While particular emphasis is placed on the effect of warping stiffness, the paper also includes results of interest in connection with the classical Michell-Prandtl-analysis of lateral buckling of endloaded cantilevers. Comprehensive numerical results are obtained for the entire range of the relevant dimensionless parameters, using power series, asymptotic expansion and modern numerical methods procedures.

  8. Effect of tip shape and dihedral on lateral-stability characteristics

    NASA Technical Reports Server (NTRS)

    Shortal, Joseph A

    1937-01-01

    This report presents the results of wind tunnel tests to determine the effect of wing-tip shape and dihedral on some of the aerodynamic characteristics of Clark Y wings that affect the performance and lateral stability of airplanes. Force tests at several angles of yaw and rotation tests at zero yaw were made. From these tests the rates of change of rolling moment, yawing moment, and cross-wind force coefficients with angle of yaw and the rate of change of rolling moment coefficient with rolling were determined.

  9. VORSTAB: A computer program for calculating lateral-directional stability derivatives with vortex flow effect

    NASA Technical Reports Server (NTRS)

    Lan, C. Edward

    1985-01-01

    A computer program based on the Quasi-Vortex-Lattice Method of Lan is presented for calculating longitudinal and lateral-directional aerodynamic characteristics of nonplanar wing-body combination. The method is based on the assumption of inviscid subsonic flow. Both attached and vortex-separated flows are treated. For the vortex-separated flow, the calculation is based on the method of suction analogy. The effect of vortex breakdown is accounted for by an empirical method. A summary of the theoretical method, program capabilities, input format, output variables and program job control set-up are described. Three test cases are presented as guides for potential users of the code.

  10. Highly efficient spin-conversion effect leading to energy up-converted electroluminescence in singlet fission photovoltaics.

    PubMed

    Pandey, Ajay K

    2015-01-01

    Free charge generation in donor-acceptor (D-A) based organic photovoltaic diodes (OPV) progresses through formation of charge-transfer (CT) and charge-separated (CS) states and excitation decay to the triplet level is considered as a terminal loss. On the other hand a direct excitation decay to the triplet state is beneficial for multiexciton harvesting in singlet fission photovoltaics (SF-PV) and the formation of CT-state is considered as a limiting factor for multiple triplet harvesting. These two extremes when present in a D-A system are expected to provide important insights into the mechanism of free charge generation and spin-character of bimolecular recombination in OPVs. Herein, we present the complete cycle of events linked to spin conversion in the model OPV system of rubrene/C60. By tracking the spectral evolution of photocurrent generation at short-circuit and close to open-circuit conditions we are able to capture spectral changes to photocurrent that reveal the triplet character of CT-state. Furthermore, we unveil an energy up-conversion effect that sets in as a consequence of triplet population build-up where triplet-triplet annihilation (TTA) process effectively regenerates the singlet excitation. This detailed balance is shown to enable a rare event of photon emission just above the open-circuit voltage (V(OC)) in OPVs. PMID:25585937

  11. Highly efficient spin-conversion effect leading to energy up-converted electroluminescence in singlet fission photovoltaics

    NASA Astrophysics Data System (ADS)

    Pandey, Ajay K.

    2015-01-01

    Free charge generation in donor-acceptor (D-A) based organic photovoltaic diodes (OPV) progresses through formation of charge-transfer (CT) and charge-separated (CS) states and excitation decay to the triplet level is considered as a terminal loss. On the other hand a direct excitation decay to the triplet state is beneficial for multiexciton harvesting in singlet fission photovoltaics (SF-PV) and the formation of CT-state is considered as a limiting factor for multiple triplet harvesting. These two extremes when present in a D-A system are expected to provide important insights into the mechanism of free charge generation and spin-character of bimolecular recombination in OPVs. Herein, we present the complete cycle of events linked to spin conversion in the model OPV system of rubrene/C60. By tracking the spectral evolution of photocurrent generation at short-circuit and close to open-circuit conditions we are able to capture spectral changes to photocurrent that reveal the triplet character of CT-state. Furthermore, we unveil an energy up-conversion effect that sets in as a consequence of triplet population build-up where triplet-triplet annihilation (TTA) process effectively regenerates the singlet excitation. This detailed balance is shown to enable a rare event of photon emission just above the open-circuit voltage (VOC) in OPVs.

  12. Highly efficient spin-conversion effect leading to energy up-converted electroluminescence in singlet fission photovoltaics

    PubMed Central

    Pandey, Ajay K.

    2015-01-01

    Free charge generation in donor-acceptor (D-A) based organic photovoltaic diodes (OPV) progresses through formation of charge-transfer (CT) and charge-separated (CS) states and excitation decay to the triplet level is considered as a terminal loss. On the other hand a direct excitation decay to the triplet state is beneficial for multiexciton harvesting in singlet fission photovoltaics (SF-PV) and the formation of CT-state is considered as a limiting factor for multiple triplet harvesting. These two extremes when present in a D-A system are expected to provide important insights into the mechanism of free charge generation and spin-character of bimolecular recombination in OPVs. Herein, we present the complete cycle of events linked to spin conversion in the model OPV system of rubrene/C60. By tracking the spectral evolution of photocurrent generation at short-circuit and close to open-circuit conditions we are able to capture spectral changes to photocurrent that reveal the triplet character of CT-state. Furthermore, we unveil an energy up-conversion effect that sets in as a consequence of triplet population build-up where triplet-triplet annihilation (TTA) process effectively regenerates the singlet excitation. This detailed balance is shown to enable a rare event of photon emission just above the open-circuit voltage (VOC) in OPVs. PMID:25585937

  13. Effect of lateral structure parameters of SiGe HBTs on synthesized active inductors

    NASA Astrophysics Data System (ADS)

    Yan-Xiao, Zhao; Wan-Rong, Zhang; Huang, Xin; Hong-Yun, Xie; Dong-Yue, Jin; Qiang, Fu

    2016-03-01

    The effect of lateral structure parameters of transistors including emitter width, emitter length, and emitter stripe number on the performance parameters of the active inductor (AI), such as the effective inductance Ls, quality factor Q, and self-resonant frequency ω0 is analyzed based on 0.35-μm SiGe BiCMOS process. The simulation results show that for AI operated under fixed current density JC, the HBT lateral structure parameters have significant effect on Ls but little influence on Q and ω0, and the larger Ls can be realized by the narrow, short emitter stripe and few emitter stripes of SiGe HBTs. On the other hand, for AI with fixed HBT size, smaller JC is beneficial for AI to obtain larger Ls, but with a cost of smaller Q and ω0. In addition, under the fixed collector current IC, the larger the size of HBT is, the larger Ls becomes, but the smaller Q and ω0 become. The obtained results provide a reference for selecting geometry of transistors and operational condition in the design of active inductors. Project supported by the Natural Science Foundation of Beijing, China (Grant Nos. 4142007 and 4122014), the National Natural Science Foundation of China (Grant No. 61574010), and the Higher Educational Science and Technology Program of Shandong Province, China (Grant No. J13LN09).

  14. Photovoltaic Roofs

    NASA Technical Reports Server (NTRS)

    Drummond, R. W., Jr.; Shepard, N. F., Jr.

    1984-01-01

    Solar cells perform two functions: waterproofing roof and generating electricity. Sections through horizontal and slanting joints show overlapping modules sealed by L-section rubber strips and side-by-side modules sealed by P-section strips. Water seeping through seals of slanting joints drains along channels. Rooftop photovoltaic array used watertight south facing roof, replacing shingles, tar, and gravel. Concept reduces cost of residential solar-cell array.

  15. Effect of Nozzle Material on Downstream Lateral Injection Cold Spray Performance

    NASA Astrophysics Data System (ADS)

    MacDonald, D.; Leblanc-Robert, S.; Fernández, R.; Farjam, A.; Jodoin, B.

    2016-06-01

    In cold gas dynamic spraying, the gas nature, process stagnation pressure and temperature, and the standoff distance are known to be important parameters that affect the deposition efficiency and coating quality. This investigation attempts to elucidate the effect of nozzle material on coatings produced using a downstream lateral injection cold spray system. Through experimentation, it is shown that the nozzle material has a substantial effect on deposition efficiency and particle velocity. It is proposed that the effects are related to complex interaction between the particles and the internal nozzle walls. The results obtained lead to the conclusion that during the particle/nozzle wall contact, a nozzle with higher thermal diffusivity transfers more heat to the particles. This heat transfer results in lower critical velocities and therefore higher deposition efficiencies, despite a noticeable reduction of particle velocities which is also attributed to particle-nozzle interactions.

  16. Effect of Nozzle Material on Downstream Lateral Injection Cold Spray Performance

    NASA Astrophysics Data System (ADS)

    MacDonald, D.; Leblanc-Robert, S.; Fernández, R.; Farjam, A.; Jodoin, B.

    2016-08-01

    In cold gas dynamic spraying, the gas nature, process stagnation pressure and temperature, and the standoff distance are known to be important parameters that affect the deposition efficiency and coating quality. This investigation attempts to elucidate the effect of nozzle material on coatings produced using a downstream lateral injection cold spray system. Through experimentation, it is shown that the nozzle material has a substantial effect on deposition efficiency and particle velocity. It is proposed that the effects are related to complex interaction between the particles and the internal nozzle walls. The results obtained lead to the conclusion that during the particle/nozzle wall contact, a nozzle with higher thermal diffusivity transfers more heat to the particles. This heat transfer results in lower critical velocities and therefore higher deposition efficiencies, despite a noticeable reduction of particle velocities which is also attributed to particle-nozzle interactions.

  17. Photovoltaic Systems Modeling and Analysis

    NASA Astrophysics Data System (ADS)

    Ali, Mir Shahed

    2010-11-01

    This thesis deals with the implementation of generalized photovoltaic model and integration of the same with 7-bus electrical utility system to evaluate the impact that the photovoltaic generator have on the utility system. Among all the impacts that the photovoltaic generator have on the utility system, voltage rise of the power distribution line at the position where the Photovoltaic generator is connected due to reverse power flow from the photovoltaic model has been one of the major problem. Therefore, this thesis proposes the steady-state simulations to evaluate the effectiveness of battery-integrated PV system on avoiding the over voltage problem. Further, fault analysis is done to study the effect of the PV model on the utility network during faults and it is deduced that the impact of the PV model on the utility system voltage during faults is nominal. The photovoltaic model/generator and the 7-bus utility system is developed using Matlab/Simulink software package. The developed photovoltaic model can be represented as PV cell, module or an array. The model is developed with icons that are easy to understand. The developed model takes into consideration cell's working temperature, amount of sunlight (irradiance) available, voltage of the circuit when the circuit is open and current of the circuit when it is shorted. The developed Photovoltaic model is then integrated with a Li-ion battery, over here battery serves two purposes first it will store the excess power from the Photovoltaic generator if any, during the day time and in night the battery acts as an generator and deliver the power to the utility or connected load with the help of an invertors.

  18. Thermal and Electrical Effects of Partial Shade in Monolithic Thin-Film Photovoltaic Modules

    SciTech Connect

    Silverman, Timothy J.; Deceglie, Michael G.; Sun, Xingshu; Garris, Rebekah L.; Alam, Muhammad Ashraful; Deline, Chris; Kurtz, Sarah

    2015-06-14

    Photovoltaic cells can be damaged by reverse bias stress, which arises during service when a monolithically integrated thin-film module is partially shaded. We introduce a model for describing a module's internal thermal and electrical state, which cannot normally be measured. Using this model and experimental measurements, we present several results with relevance for reliability testing and module engineering: Modules with a small breakdown voltage experience less stress than those with a large breakdown voltage, with some exceptions for modules having light-enhanced reverse breakdown. Masks leaving a small part of the masked cells illuminated can lead to very high temperature and current density compared to masks covering entire cells.

  19. Thermal and Electrical Effects of Partial Shade in Monolithic Thin-Film Photovoltaic Modules: Preprint

    SciTech Connect

    Silverman, Timothy J.; Deceglie, Michael G.; Sun, Xingshu; Garris, Rebekah L.; Alam, Muhammad Ashraful; Deline, Chris; Kurtz, Sarah

    2015-09-02

    Photovoltaic cells can be damaged by reverse bias stress, which arises during service when a monolithically integrated thin-film module is partially shaded. We introduce a model for describing a module's internal thermal and electrical state, which cannot normally be measured. Using this model and experimental measurements, we present several results with relevance for reliability testing and module engineering: Modules with a small breakdown voltage experience less stress than those with a large breakdown voltage, with some exceptions for modules having light-enhanced reverse breakdown. Masks leaving a small part of the masked cells illuminated can lead to very high temperature and current density compared to masks covering entire cells.

  20. Accelerated and Outdoor Aging Effects on Photovoltaic Module Interfacial Adhesion Properties

    SciTech Connect

    Jorgensen, G. J.; McMahon, T. J.

    2008-01-01

    We have developed an apparatus that allows the measurement of applied torque as a function of angle of twist during shear removal of cored specimens. This allows us to characterize the strength and durability of various interfaces within many types of photovoltaic (PV) modules. We have used this device to evaluate several parameters in terms of their ability to quantify degradation of interfacial adhesion in weathered PV modules. The usefulness of shear modulus in this regard is marginal. However, peak torque, angle at peak torque, and toughness are very sensitive parameters.

  1. Residential Photovoltaic Energy Systems in California: The Effect on Home Sales Prices

    SciTech Connect

    Hoen, Ben; Wiser, Ryan; Thayer, Mark; Cappers, Peter

    2012-04-15

    Relatively little research exists estimating the marginal impacts of photovoltaic (PV) energy systems on home sale prices. Using a large dataset of California homes that sold from 2000 through mid-2009, we find strong evidence, despite a variety of robustness checks, that existing homes with PV systems sold for a premium over comparable homes without PV systems, implying a near full return on investment. Premiums for new homes are found to be considerably lower than those for existing homes, implying, potentially, a tradeoff between price and sales velocity. The results have significant implications for homeowners, builders, appraisers, lenders, and policymakers.

  2. Lateral spin-orbit coupling and the Kondo effect in quantum dots

    NASA Astrophysics Data System (ADS)

    Vernek, Edson; Ngo, Anh; Ulloa, Sergio

    2010-03-01

    We present studies of the Coulomb blockade and Kondo regimes of transport of a quantum dot connected to current leads through spin-polarizing quantum point contacts (QPCs) [1]. This configuration, arising from the effect of lateral spin-orbit fields, results in spin-polarized currents even in the absence of external magnetic fields and greatly affects the correlations in the dot. Using an equation-of-motion technique and numerical renormalization group calculations we obtain the conductance and spin polarization for this system under different parameter regimes. Our results show that both the Coulomb blockade and Kondo regimes exhibit non-zero spin-polarized conductance. We analyze the role that the spin-dependent tunneling amplitudes of the QPC play in determining the charge and net magnetic moment in the dot. We find that the Kondo regime exhibits a strongly dependent Kondo temperature on the QPC polarizability. These effects, controllable by lateral gate voltages, may provide a new approach for exploring Kondo correlations, as well as possible spin devices. Supported by NSF DMR-MWN and PIRE. [1] P. Debray et al., Nature Nanotech. 4, 759 (2009).

  3. Effect of gyro verticality error on lateral autoland tracking performance for an inertially smoothed control law

    NASA Technical Reports Server (NTRS)

    Thibodeaux, J. J.

    1977-01-01

    The results of a simulation study performed to determine the effects of gyro verticality error on lateral autoland tracking and landing performance are presented. A first order vertical gyro error model was used to generate the measurement of the roll attitude feedback signal normally supplied by an inertial navigation system. The lateral autoland law used was an inertially smoothed control design. The effect of initial angular gyro tilt errors (2 deg, 3 deg, 4 deg, and 5 deg), introduced prior to localizer capture, were investigated by use of a small perturbation aircraft simulation. These errors represent the deviations which could occur in the conventional attitude sensor as a result of the maneuver-induced spin-axis misalinement and drift. Results showed that for a 1.05 deg per minute erection rate and a 5 deg initial tilt error, ON COURSE autoland control logic was not satisfied. Failure to attain the ON COURSE mode precluded high control loop gains and localizer beam path integration and resulted in unacceptable beam standoff at touchdown.

  4. The PRP Effect Following Callosotomy: Residual Interference Despite Uncoupling of Lateralized Response Codes

    NASA Technical Reports Server (NTRS)

    Ivry, Richard B.; Franz, Elizabeth A.; Kingstone, Alan; Johnston, James C.; Null, Cynthia H. (Technical Monitor)

    1995-01-01

    A callosotomy patient was tested in two dual-task experiments requiring successive speeded responses to lateralized stimuli. In accord with the recent findings of Pashler, O'Brien, Luck, Hillyard, Mangun, and Gazzaniga (in press), the patient showed a robust psychological refractory period effect (PRP) responses on Task 2 were inversely related to the stimulus-onset asynchrony (SOA). However, three aspects of our data indicated that the processing limitations for the patient were different than those observed with control subjects. First, the split-brain patient did not show an increase in reaction time when the two tasks required responses from a common output system (i.e., both manual responses) in comparison to when different output systems were used (i.e., manual-vocal). Second, inconsistent stimulus-response mappings for the two tasks greatly inflated response latencies for the control subjects, but had minimal effect on the performance of the split-brain patient. Third, the consistency manipulation was underadditive with SOA for only the patient, suggesting a later bottleneck in processing following callosotomy than was observed for the control subjects. It is proposed that sectioning the corpus callosum eliminates interference resulting from competing stimulus response codes. Nonetheless, dual-task interference persists for the split-brain subject because a subcortical gate constrains when selected responses can be implemented.

  5. Effects of platelet-rich plasma on lateral epicondylitis of the elbow: prospective randomized controlled trial☆

    PubMed Central

    Palacio, Evandro Pereira; Schiavetti, Rafael Ramos; Kanematsu, Maiara; Ikeda, Tiago Moreno; Mizobuchi, Roberto Ryuiti; Galbiatti, José Antônio

    2016-01-01

    Objective To evaluate the effects of platelet-rich plasma (PRP) infiltration in patients with lateral epicondylitis of the elbow, through analysis of the Disabilities of the Arm, Shoulder and Hand (DASH) and Patient-Rated Tennis Elbow Evaluation (PRTEE) questionnaires. Methods Sixty patients with lateral epicondylitis of the elbow were prospectively randomized and evaluated after receiving infiltration of three milliliters of PRP, or 0.5% neocaine, or dexamethasone. For the scoring process, the patients were asked to fill out the DASH and PRTEE questionnaires on three occasions: on the day of infiltration and 90 and 180 days afterwards. Results Around 81.7% of the patients who underwent the treatment presented some improvement of the symptoms. The statistical tests showed that there was evidence that the cure rate was unrelated to the substance applied (p = 0.62). There was also intersection between the confidence intervals of each group, thus demonstrating that the proportions of patients whose symptoms improved were similar in all the groups. Conclusion At a significance level of 5%, there was no evidence that one treatment was more effective than another, when assessed using the DASH and PRTEE questionnaires. PMID:26962506

  6. Lateralized effect of rapid-rate transcranial magnetic stimulation of the prefrontal cortex on mood.

    PubMed

    Pascual-Leone, A; Catalá, M D; Pascual-Leone Pascual, A

    1996-02-01

    We studied the effects of rapid-rate transcranial magnetic stimulation (rTMS) of different scalp positions on mood. Ten normal volunteers rated themselves before and after rTMS on five analog scales labeled "Tristeza" (Sadness), "Ansiedad" (Anxiety), "Alegria" (Happiness), "Cansancio" (Tiredness), and "Dolor/Malestar" (Pain/Discomfort). rTMS was applied to the right lateral prefrontal, left prefrontal, or midline frontal cortex in trains of 5 seconds' duration at 10 Hz and 110% of the subject's motor threshold intensity. Each stimulation position received 10 trains separated by a 25-second pause. No clinically apparent mood changes were evoked by rTMS to any of the scalp positions in any subject. However, left prefrontal rTMS resulted in a significant increase in the Sadness ratings (Tristeza) and a significant decrease in the Happiness ratings ("Alegria") as compared with right prefrontal and midfrontal cortex stimulation. These results show differential effects of rTMS of left and right prefrontal cortex stimulation on mood and illustrate the lateralized control of mood in normal volunteers. PMID:8614521

  7. The Effect of Interfacial Geometry on Charge-Transfer States in the Phthalocyanine/Fullerene Organic Photovoltaic System.

    PubMed

    Lee, Myeong H; Geva, Eitan; Dunietz, Barry D

    2016-05-19

    The dependence of charge-transfer states on interfacial geometry at the phthalocyanine/fullerene organic photovoltaic system is investigated. The effect of deviations from the equilibrium geometry of the donor-donor-acceptor trimer on the energies of and electronic coupling between different types of interfacial electronic excited states is calculated from first-principles. Deviations from the equilibrium geometry are found to destabilize the donor-to-donor charge transfer states and to weaken their coupling to the photoexcited donor-localized states, thereby reducing their ability to serve as charge traps. At the same time, we find that the energies of donor-to-acceptor charge transfer states and their coupling to the donor-localized photoexcited states are either less sensitive to the interfacial geometry or become more favorable due to modifications relative to the equilibrium geometry, thereby enhancing their ability to serve as gateway states for charge separation. Through these findings, we eludicate how interfacial geometry modifications can play a key role in achieving charge separation in this widely studied organic photovoltaic system. PMID:26237431

  8. Photovoltaic effect in an indium-tin-oxide/ZnO/BiFeO{sub 3}/Pt heterostructure

    SciTech Connect

    Fan, Zhen; Yao, Kui E-mail: msewangj@nus.edu.sg; Wang, John E-mail: msewangj@nus.edu.sg

    2014-10-20

    We have studied the photovoltaic effect in a metal/semiconductor/ferroelectric/metal heterostructure of In{sub 2}O{sub 3}-SnO{sub 2}/ZnO/BiFeO{sub 3}/Pt (ITO/ZnO/BFO/Pt) multilayer thin films. The heterolayered structure shows a short-circuit current density (J{sub sc}) of 340 μA/cm{sup 2} and an energy conversion efficiency of up to 0.33% under blue monochromatic illumination. The photovoltaic mechanism, specifically in terms of the major generation site of photo-excited electron-hole (e-h) pairs and the driving forces for the separation of e-h pairs, is clarified. The significant increase in photocurrent of the ITO/ZnO/BFO/Pt compared to that of ITO/BFO/Pt is attributed to the abundant e-h pairs generated from ZnO. Ultraviolet photoelectron spectroscopy reveals the energy band alignment of ITO/ZnO/BFO/Pt, where a Schottky barrier and an n{sup +}-n junction are formed at the BFO/Pt and ZnO/BFO interfaces, respectively. Therefore, two built-in fields developed at the two interfaces are constructively responsible for the separation and transport of photo-excited e-h pairs.

  9. The effects of junction interdiffusion and misfit dislocations on the efficiency of highly mismatched heterojunction photovoltaic devices

    NASA Astrophysics Data System (ADS)

    Mendis, B. G.; Treharne, R. E.; Lane, D. W.; Durose, K.

    2016-05-01

    A general modelling methodology has been developed to evaluate the effects of chemical interdiffusion and misfit dislocations on the performance of heterojunction solar cells made from highly mismatched materials. Results for the exemplar materials system CdS-CdTe are contrary to the widely held belief that such interdiffusion is beneficial to photovoltaic performance. In the model, recombination is presumed to take place at the cores of misfit dislocations, with the distribution of these dislocations in the interdiffused layer being calculated so as to minimise the total energy (an incidental result shows that the total number of dislocations is independent of the diffusion profile). The model takes calculated chemical profiles, optical absorption, and dislocation distributions from which the photovoltaic performance and recombination losses are evaluated. It was shown that for the realistic case in which the interdiffused region does not extend beyond the space charge region, the photovoltage losses dominate over any photocurrent gains. Methods to engineer mixed junctions that may increase solar conversion efficiency are discussed.

  10. Effect of potassium iodide on luminescent and photovoltaic properties of organic solar cells P3HT-PCBM

    NASA Astrophysics Data System (ADS)

    Ibrayev, N. Kh; Afanasyev, D. A.; Zhapabaev, K. A.

    2016-02-01

    It has been investigated spectral-luminescence properties of polymer films, doped with potassium iodide (KI). Using of KI didn't lead to the gradual changes of optical density of polymer films and the range of band gap semiconductor polymer P3HT. The fluorescence intensity of P3HT decreased and changed by use of KI. Using of 1% KI in polymer leaded to decrease of fluorescence lifetime. Influence of heavy atom on photovoltaic effect of organic solar cells has been investigated. 1% of KI in polymer film leaded to decrease of Isc and slightly decrease of Uoc. Investigation shows that magnetic field does not affect on photovoltaic properties of cells P3HT-PCBM. Magnetic field increased of open circuit voltage and short circuit current of solar cells with 1% of KI. Study of electrical impedance of cells revealed the magnetic sensivity of solar cells with KI additives. The lifetime of free charge carriers increased in the magnetic field for solar cells with KI additives.

  11. Gate-tunable diode and photovoltaic effect in an organic-2D layered material p-n junction.

    PubMed

    Vélez, Saül; Ciudad, David; Island, Joshua; Buscema, Michele; Txoperena, Oihana; Parui, Subir; Steele, Gary A; Casanova, Fèlix; van der Zant, Herre S J; Castellanos-Gomez, Andres; Hueso, Luis E

    2015-10-01

    The semiconducting p-n junction is a simple device structure with great relevance for electronic and optoelectronic applications. The successful integration of low-dimensional materials in electronic circuits has opened the way forward for producing gate-tunable p-n junctions. In that context, we present here an organic (Cu-phthalocyanine)-2D layered material (MoS2) hybrid p-n junction with both gate-tunable diode characteristics and photovoltaic effect. Our proof-of-principle devices show multifunctional properties with diode rectifying factors of up to 10(4), while under light exposure they exhibit photoresponse with a measured external quantum efficiency of ∼11%. As for their photovoltaic properties, we found open circuit voltages of up to 0.6 V and optical-to-electrical power conversion efficiency of 0.7%. The extended catalogue of known organic semiconductors and two-dimensional materials offer the prospect for tailoring the properties and the performance of the resulting devices, making organic-2D p-n junctions promising candidates for future technological applications. PMID:26335856

  12. Effects of lateral tip control in CD-AFM width metrology

    NASA Astrophysics Data System (ADS)

    Dixson, Ronald; Ng, Boon Ping; Orji, Ndubuisi

    2014-09-01

    Critical dimension atomic force microscopes (CD-AFMs) use flared tips and two-dimensional sensing and position control of the tip-sample interaction to enable scanning of features with near-vertical or reentrant sidewalls. Sidewall sensing usually involves lateral dither of the tip, which was the case in the first two generations of CD-AFM. Current, third-generation instruments also have a fast dither tube actuation (FDTA) mode where a control algorithm and fast response piezo actuator are used to position the tip in a manner that resembles touch-triggering of coordinate measuring machines (CMMs). All methods of tip position control, however, induce an effective tip width that may deviate from the actual geometrical tip width. When lateral dithering is involved, this effect is readily understood as the addition of a dither envelope to the geometrical tip width. The effective tip width is a key correction parameter for accurate feature width measurements and is typically estimated using a tip calibration procedure. However, the possibility exists of small errors in the estimated tip width due to variations and dependencies of the effective width on tip, tool, material, and environmental parameters. We are investigating this possibility through a systematic study of the dependence of the apparent width on measurement mode, dither amplitude, tip type, and sample composition. While we believe that there are potential effects that should be considered carefully, we also conclude, particularly for silicon features, that most potential biases can be removed by performing the calibration and measurement exercises under the same conditions.

  13. Perfectionism, neuroticism, and daily stress reactivity and coping effectiveness 6 months and 3 years later.

    PubMed

    Dunkley, David M; Mandel, Tobey; Ma, Denise

    2014-10-01

    The present study addressed a fundamental gap between research and clinical work by advancing longitudinal explanatory conceptualizations of stress and coping processes that trigger daily affect in the short- and long-term for individuals with higher levels of personality vulnerability. Community adults completed measures of 2 higher order dimensions of perfectionism (personal standards [PS], self-criticism [SC]), neuroticism, and conscientiousness. Then, 6 months later and again 3 years later, participants completed daily questionnaires of stress, coping, and affect for 14 consecutive days. PS was associated with aggregated daily problem-focused coping and positive reinterpretation, whereas SC was uniquely associated with daily negative social interactions, avoidant coping, negative affect, and sadness at Month 6 and Year 3. Multilevel modeling results demonstrated that both individuals with higher PS and those with higher SC were emotionally reactive to event stress, negative social interactions, and avoidant coping at Month 6 and Year 3 and to less perceived control at Year 3. Positive reinterpretation was especially effective for individuals with higher SC at Month 6 and Year 3. The effects of PS on daily stress reactivity and coping (in)effectiveness were clearly distinguished from the effects of neuroticism and conscientiousness, whereas the SC effects were due to shared overlap with PS and neuroticism. The present findings demonstrate the promise of using repeated daily diary methodologies to help therapists and clients reliably predict future client reactions to daily stressors, which, in turn, could help guide interventions to break apart dysfunctional patterns connected to distress and build resilience for vulnerable individuals. PMID:25111703

  14. Postural laterality in Iberian ibex Capra pyrenaica: effects of age, sex and nursing suggest stress and social information.

    PubMed

    Sarasa, Mathieu; Soriguer, Ramón C; Serrano, Emmanuel; Granados, José-Enrique; Pérez, Jesús M

    2014-01-01

    Most studies of lateralized behaviour have to date focused on active behaviour such as sensorial perception and locomotion and little is known about lateralized postures, such as lying, that can potentially magnify the effectiveness of lateralized perception and reaction. Moreover, the relative importance of factors such as sex, age and the stress associated with social status in laterality is now a subject of increasing interest. In this study, we assess the importance of sex, age and reproductive investment in females in lying laterality in the Iberian ibex (Capra pyrenaica). Using generalized additive models under an information-theoretic approach based on the Akaike information criterion, we analyzed lying laterality of 78 individually marked ibexes. Sex, age and nursing appeared as key factors associated, in interaction and non-linearly, with lying laterality. Beyond the benefits of studying laterality with non-linear models, our results highlight the fact that a combination of static factors such as sex, and dynamic factors such as age and stress associated with parental care, are associated with postural laterality. PMID:24611891

  15. Effect of friction in Dual Equal Channel Lateral Extrusion using finite element simulation

    NASA Astrophysics Data System (ADS)

    Xiaoqi, Wang; Qingnan, Shi; Huarong, Qi; Zhaohua, Liu

    2014-08-01

    Dual equal channel lateral extrusion (DECLE) is a type of equal channel angular pressing which employs T-shaped die instead of L-shaped die. In the present work, deformation behavior in the DECLE process is analyzed by using DEFOEM-2D. The effect of friction between the die channels and the specimen on the effective strain distribution homogeneity and load were investigated. The friction induces inhomogeneous deformation in the head, top and bottom regions of the work piece. As friction increases, the top gap becomes smaller and the strain distribution becomes more homogenous, but the maximum load value increases. These results can serve as a design for reasonably technological parameters for DECLE processing.

  16. Some effects of Field Of View (FOV) and target size on lateral tracking at hover

    NASA Technical Reports Server (NTRS)

    Breul, H. T.

    1981-01-01

    An exploratory flight-simulator experiment examined the gross effects of several factors potentially important to the design of a visual display system for aiding VTOL pilots in the difficult task of landing on a small sea-control ship. Field of view (FOV) and target size were the primary variables examined for a lateral tracking task in a full motion 5 degree-of-freedom hover simulation. The mean absolute value of tracking error was used to measure tracking performance, and cross spectral transfer function analysis was performed to determine the pilot's ability to generate good open-loop transfer function characteristics as a function of the experimental variables. It was found that FOV and target size can have a large effect on the pilot's ability to generate open-loop gain, and on his tracking performance.

  17. Effects of cerium removal from glass on photovoltaic module performance and stability

    NASA Astrophysics Data System (ADS)

    Kempe, Michael D.; Moricone, Thomas; Kilkenny, Matt

    2009-08-01

    Photovoltaic modules are exposed to extremely harsh conditions of heat, humidity, high voltage, mechanical stress, thermal cycling and ultraviolet (UV) radiation. The current qualification tests (e.g. IEC 61215) do not require sufficient UV exposure to evaluate lifespans of 30 years. Recently, photovoltaic panel manufacturers have been using glass that does not contain Cerium. This has the advantage of providing about 1.3% to 1.8% more photon transmission but potentially at the expense of long term stability. The additional transmission of light in the 300 nm to 340 nm range can cause delamination to occur about 3.8 times faster. Similarly, UV radiation will cause polymeric encapsulants, such as ethylene vinyl-acetate (EVA), to turn yellow faster losing photon transmission. Silicones do not suffer from light induced degradation as hydrocarbon based polymers do, therefore if silicone encapsulants are used, a 1.6% to 1.9% increase in photon transmission can be obtained from removal of Ce from glass, with no tradeoff in long term stability. Additionally antimony can be added to non-Ce containing glass to further improve photon transmission (principally in the IR range) by an additional 0.4% to 0.7%; however, this does not significantly affect UV transmission so the same UV induced reliability concerns will still exist with common hydrocarbon-based encapsulants.

  18. Proceedings of the 15th Space Photovoltaic Research and Technology Conference

    NASA Technical Reports Server (NTRS)

    Bailey, Sheila (Compiler)

    2004-01-01

    Reports from the 15th Space Photovoltaic Research and Technology Conference included topics on space solar cell research, space photovoltaics, multibandgap cells,thermophotovoltaics,flight experiments, environmental effects; calibration and characterization; and photovoltaics for planetary surfaces.

  19. Photovoltaic Materials

    SciTech Connect

    Duty, C.; Angelini, J.; Armstrong, B.; Bennett, C.; Evans, B.; Jellison, G. E.; Joshi, P.; List, F.; Paranthaman, P.; Parish, C.; Wereszczak, A.

    2012-10-15

    The goal of the current project was to help make the US solar industry a world leader in the manufacture of thin film photovoltaics. The overall approach was to leverage ORNL’s unique characterization and processing technologies to gain a better understanding of the fundamental challenges for solar cell processing and apply that knowledge to targeted projects with industry members. ORNL has the capabilities in place and the expertise required to understand how basic material properties including defects, impurities, and grain boundaries affect the solar cell performance. ORNL also has unique processing capabilities to optimize the manufacturing process for fabrication of high efficiency and low cost solar cells. ORNL recently established the Center for Advanced Thin-film Systems (CATS), which contains a suite of optical and electrical characterization equipment specifically focused on solar cell research. Under this project, ORNL made these facilities available to industrial partners who were interested in pursuing collaborative research toward the improvement of their product or manufacturing process. Four specific projects were pursued with industrial partners: Global Solar Energy is a solar industry leader in full scale production manufacturing highly-efficient Copper Indium Gallium diSelenide (CIGS) thin film solar material, cells and products. ORNL worked with GSE to develop a scalable, non-vacuum, solution technique to deposit amorphous or nanocrystalline conducting barrier layers on untextured stainless steel substrates for fabricating high efficiency flexible CIGS PV. Ferro Corporation’s Electronic, Color and Glass Materials (“ECGM”) business unit is currently the world’s largest supplier of metallic contact materials in the crystalline solar cell marketplace. Ferro’s ECGM business unit has been the world's leading supplier of thick film metal pastes to the crystalline silicon PV industry for more than 30 years, and has had operational cells and

  20. Interaction at the silicon/transition metal oxide heterojunction interface and its effect on the photovoltaic performance.

    PubMed

    Liang, Zhimin; Su, Mingze; Zhou, Yangyang; Gong, Li; Zhao, Chuanxi; Chen, Keqiu; Xie, Fangyan; Zhang, Weihong; Chen, Jian; Liu, Pengyi; Xie, Weiguang

    2015-11-01

    The interfacial reaction and energy level alignment at the Si/transition metal oxide (TMO, including MoO3-x, V2O5-x, WO3-x) heterojunction are systematically investigated. We confirm that the interfacial reaction appears during the thermal deposition of TMO, with the reaction extent increasing from MoO3-x, to V2O5-x, and to WO3-x. The reaction causes the surface oxidation of silicon for faster electron/hole recombination, and the reduction of TMO for effective hole collection. The photovoltaic performance of the Si/TMO heterojunction devices is affected by the interface reaction. MoO3-x are the best hole selecting materials that induce least surface oxidation but strongest reduction. Compared with H-passivation, methyl group passivation is an effective way to reduce the interface reaction and improve the interfacial energy level alignment for better electron and hole collection. PMID:26422643

  1. Effects of eccentricities and lateral pressure on the design of stiffened compression panels

    NASA Technical Reports Server (NTRS)

    Giles, G. L.; Anderson, M. S.

    1972-01-01

    An analysis for determining the effects of eccentricities and lateral pressure on the design of stiffened compression panels is presented. The four types of panel stiffeners considered are integral, zee, integral zee, and integral tee. Mass-strength curves, which give the mass of the panel necessary to carry a specified load, are given along with related design equations needed to calculate the cross-sectional dimensions of the minimum-mass-stiffened panel. The results of the study indicate that the proportions of the panels are geometrically similar to the proportions of panels designed for no eccentricity or lateral pressure, but no cross-sectional dimensions are greater, resulting in significantly increased mass. The analytical minimum-mass designs of zee-stiffened panels are compared with designs from experimentally derived charts. An assumed eccentricity of 0.001 times the length of the panel is used to correlate the analytical and experimental data. Good correlation between the experimentally derived and the analytical curves is obtained for the range of loading where materials yield governs the design. At lower loads the mass given by the analytical curve using this assumed eccentricity is greater than that given by the experimental results.

  2. The effects of a lateral in-flight perturbation on lower extremity biomechanics during drop landings.

    PubMed

    Yom, Jae P; Simpson, Kathy J; Arnett, Scott W; Brown, Cathleen N

    2014-10-01

    One potential ACL injury situation is due to contact with another person or object during the flight phase, thereby causing the person to land improperly. Conversely, athletes often have flight-phase collisions but do land safely. Therefore, to better understand ACL injury causation and methods by which people typically land safely, the purpose of this study was to determine the effects of an in-flight perturbation on the lower extremity biomechanics displayed by females during typical drop landings. Seventeen collegiate female recreational athletes performed baseline landings, followed by either unexpected laterally-directed perturbation or sham (nonperturbation) drop landings. We compared baseline and perturbation trials using paired-samples t tests (P < .05) and 95% confidence intervals for lower-extremity joint kinematics and kinetics and GRF. The results demonstrated that perturbation landings compared with baseline landings exhibited more extended joint positions of the lower extremity at initial contact; and, during landing, greater magnitudes for knee abduction and hip adduction displacements; peak magnitudes of vertical and medial GRF; and maximum moments of ankle extensors, knee extensors, and adductor and hip adductors. We conclude that a lateral in-flight perturbation leads to abnormal GRF and angular motions and joint moments of the lower extremity. PMID:25010630

  3. Accelerated Thermal-Aging-Induced Degradation of Organometal Triiodide Perovskite on ZnO Nanostructures and Its Effect on Hybrid Photovoltaic Devices.

    PubMed

    Kumar, S; Dhar, A

    2016-07-20

    Organometal halide perovskite materials are presently some of the pacesetters for light harvesting in hybrid photovoltaic devices because of their excellent inherent electrical and optical properties. However, long-term durability of such perovskite materials remains a major bottleneck for their commercialization especially in countries with hot and humid climatic conditions, thus violating the international standards for photovoltaic technology. Albeit, TiO2 as an electron-transport layer has been well investigated for perovskite solar cells; the high-temperature processing makes it unsuitable for low-cost and large-scale roll-to-roll production of flexible photovoltaic devices. Herein, we have chosen low-temperature (<150 °C)-processable nanostructured ZnO as the electron-selective layer and used a two-step method for sensitizing ZnO nanorods with methylammonium lead iodide (MAPbI3) perovskite, which is viable for flexible photovoltaic devices. We have also elaborately addressed the effect of the annealing duration on the conversion of a precursor solution into the required perovskite phase on ZnO nanostructures. The investigations show that the presence of ZnO nanostructures accelerates the rate of degradation of MAPbI3 films under ambient annealing and thus requires proper optimization. The role of ZnO in enhancing the degradation kinetics of the perovskite layer has been investigated by X-ray photoelectron spectroscopy and a buffer layer passivation technique. The effect of the annealing duration of the MAPbI3 perovskite on the optical, morphological, and compositional behavior has been closely studied and correlated with the photovoltaic efficiency. The study captures the degradation behavior of the commercially interesting MAPbI3 perovskite on a ZnO electron-transport layer and thus can provide insight for developing alternative families of perovskite material with better thermal and environmental stability for application in low-cost flexible photovoltaic

  4. Perceptual and motor laterality effects in pianists during music sight-reading.

    PubMed

    D'Anselmo, Anita; Giuliani, Felice; Marzoli, Daniele; Tommasi, Luca; Brancucci, Alfredo

    2015-05-01

    Forty-six right-handed pianists were tested in a music sight-reading task in which they had to perform on a keyboard. Stimuli were single notes or single triads (chords) presented tachistoscopically in the left or right visual field in form of musical notation or verbal labels. Left-hand, right-hand or two-hands performance was required. Results showed, besides the expected Simon effect producing faster responses for stimuli to be performed with the hand ipsilateral to the side of presentation, a complex pattern of laterality which depended primarily upon the requested motor output. A tendency in favor of the left hemisphere (right visual field, RVF) was observed, this asymmetry being significant only in the single-hand tasks. On the contrary, in the two-hands task an opposite asymmetry was observed with musical notation. Moreover, a strong unexpected role of the bass clef was observed, which penalized left hand performance in particular with LVF stimuli. This effect even overcame the Simon effect, suggesting the presence of a bias in favor of the left hemisphere in musical transposition. Results point to a variegated pattern of hemispheric asymmetries in music sight-reading which depend on both stimulus coding and motor output type (e.g. two- or single-hand performance). A RH asymmetry was observed during two-hands playing with musical notation. Conversely, playing with one hand seems more leftward lateralized. This pattern of asymmetry would reflect a LH ability in simple "core" music reading together with a RH ability in the coordination of simultaneous responses by the two hands. PMID:25817847

  5. The Effect of Emboss Enhancement on Reliability of Landmark Identification in Digital Lateral Cephalometric Images

    PubMed Central

    Nikneshan, Sima; Mohseni, Sudeh; Nouri, Mahtab; Hadian, Hoora; Kharazifard, Mohammad Javad

    2015-01-01

    Background: Evaluation of the craniofacial bones is the oldest method to measure the facial proportion ratio in orthodontics. Objectives: The purpose of this study was to evaluate the effect of emboss enhancement on the reliability of landmark identification in digital lateral cephalometric images. Materials and Methods: Ten digital lateral cephalograms were selected from the archive of an oral and maxillofacial radiology center. Using DIGORA software, these images were saved in two formats; common images and 3D emboss images. On these images, 32 skeletal, dental, and soft tissue landmarks were marked at least twice with a 2-week interval by four observers (two radiologists and two orthodontists). In order to determine the position of the marked landmarks (in x and y coordinates), a software was designed. The statistical analysis was performed in SPSS software and the reliability of each observer was obtained by means of intraclass correlation coefficient (ICC). Results: In three skeletal landmarks [Orbit (Or), condyl top (Cond), and pogonion (Pog)], the enhancement caused significant reduction in the reliability, and in four skeletal [Anterior Nasal Spine (ANS), B, A, and Basion (Ba)], two dental (U1 root, L1 incisal), and one soft tissue landmark (Menton soft tissue), the enhancement increased the reliability of landmark detection between the two phases of the study. Totally, ICC of embossed images in both x and y coordinates were greater than the typical images, but the difference was not statistically significant. However, the effect of enhancement on the improvement of the reliability of landmark identification was higher in the x-axis than the y-axis. Conclusions: Using embossed images is only effective in increasing the reliability of detection in a few numbers of cephalometric landmarks. PMID:26060555

  6. Arabidopsis thaliana RALF1 opposes brassinosteroid effects on root cell elongation and lateral root formation

    PubMed Central

    Moura, Daniel S.

    2014-01-01

    Rapid alkalinization factor (RALF) is a peptide signal that plays a basic role in cell biology and most likely regulates cell expansion. In this study, transgenic Arabidopsis thaliana lines with high and low levels of AtRALF1 transcripts were used to investigate this peptide’s mechanism of action. Overexpression of the root-specific isoform AtRALF1 resulted in reduced cell size. Conversely, AtRALF1 silencing increased root length by increasing the size of root cells. AtRALF1-silenced plants also showed an increase in the number of lateral roots, whereas AtRALF1 overexpression produced the opposite effect. In addition, four AtRALF1-inducible genes were identified: two genes encoding proline-rich proteins (AtPRP1 and AtPRP3), one encoding a hydroxyproline-rich glycoprotein (AtHRPG2), and one encoding a xyloglucan endotransglucosylase (TCH4). These genes were expressed in roots and involved in cell-wall rearrangement, and their induction was concentration dependent. Furthermore, AtRALF1-overexpressing plants were less sensitive to exogenous brassinolide (BL); upon BL treatment, the plants showed no increase in root length and a compromised increase in hypocotyl elongation. In addition, the treatment had no effect on the number of emerged lateral roots. AtRALF1 also induces two brassinosteroid (BR)-downregulated genes involved in the BR biosynthetic pathway: the cytochrome P450 monooxygenases CONSTITUTIVE PHOTOMORPHISM AND DWARFISM (CPD) and DWARF4 (DWF4). Simultaneous treatment with both AtRALF1 and BL caused a reduction in AtRALF1-inducible gene expression levels, suggesting that these signals may compete for components shared by both pathways. Taken together, these results indicate an opposing effect of AtRALF1 and BL, and suggest that RALF’s mechanism of action could be to interfere with the BR signalling pathway. PMID:24620000

  7. Correction: Dye adsorption mechanisms in TiO2 films, and their effects on the photodynamic and photovoltaic properties in dye-sensitized solar cells.

    PubMed

    Hwang, Kyung-Jun; Shim, Wang-Geun; Kim, Dajung; An, Jongdeok; Im, Chan; Kim, Youngjin; Kim, Gunwoo; Choi, Chulmin; Kang, Sang Ook; Cho, Dae Won

    2016-02-21

    Correction for 'Dye adsorption mechanisms in TiO2 films, and their effects on the photodynamic and photovoltaic properties in dye-sensitized solar cells' by Kyung-Jun Hwang et al., Phys. Chem. Chem. Phys., 2015, 17, 21974-21981. PMID:26792293

  8. Geometric effects of global lateral heterogeneity on long-period surface wave propagation

    NASA Technical Reports Server (NTRS)

    Lay, T.; Kanamori, H.

    1985-01-01

    The present investigation has the objective to document examples of anomalous long-period surface wave amplitude behavior and to provide a preliminary appraisal of the effects of global lateral heterogeneity on surface wave propagation from a ray theory perspective. Attention is given to remarkable long-period surface wave anomalies described in literature, an equidistance azimuthal plot centered on the Iranian source region, Rayleigh wave and Love wave spectra for the 256-s period arrivals for the Tabas earthquake, constrained moment tensor and fault model inversion solutions ofr Iranian earthquakes, aspects of surface wave ray tracing, and a table of Rayleigh wave amplitude anomalies for Iranian earthquakes. Surface wave ray-tracing calculations for models of global phase velocity variations proposed by Nakanishi and Anderson (1984) are found to show that large-amplitude anomalies will be observed for Love and Rayleigh waves with periods of 100-250 s.

  9. Effects of lateral variations in megaregolith thickness on predicted lunar seismic signals

    NASA Astrophysics Data System (ADS)

    Blanchette-Guertin, J.-F.; Johnson, C. L.; Lawrence, J. F.

    2015-12-01

    We use a modified phonon synthetic seismogram method to investigate the effects of laterally varying megaregolith thickness on the propagation of seismic energy and on the resulting seismic signals recorded at various epicentral distances from the source. We show that receivers located in large impact structures, with thin crust and thinner megaregolith, can record seismic signals that are less affected by high levels of scattering. In particular, receivers located away from the basin edge by a distance greater than or equal to the thickness of the surrounding megaregolith can record seismograms in which secondary arrivals containing important information about interior structure can be more readily identified. Seismic sources located beneath the near-surface scattering layer, such as deep lunar quakes, are also advantageous because the resulting seismograms are less affected by high levels of scattering than those from sources within the scattering layer or surface impacts.

  10. Small alcohols destabilize the KcsA tetramer via their effect on the membrane lateral pressure.

    PubMed

    van den Brink-van der Laan, Els; Chupin, Vladimir; Killian, J Antoinette; de Kruijff, Ben

    2004-05-25

    Previously, it was shown that the tetrameric potassium channel KcsA when present in a lipid bilayer can be dissociated by trifluoroethanol [van den Brink-van der Laan, E., et al. (2004) Biochemistry 43, 4240-4250]. Here, we demonstrate that this is a general property of small alcohols. We found that small alcohols dissociate the KcsA tetramer, at a concentration that depends on their membrane affinity. Importantly, the efficiency of the alcohol-induced tetramer dissociation was found to correlate with the efficiency of both alcohol-induced bilayer leakage and acyl chain disordering. Our data suggest that the ability of small alcohols to induce KcsA tetramer dissociation and to function as anesthetics depends on their effect on the membrane lateral pressure. PMID:15147177

  11. Effects of cerebral hemispheric laterality on the span of apprehension of schizophrenic and healthy subjects.

    PubMed

    Mass, R; Schoemig, T; Novikov, J; Wagner, M

    2001-01-01

    The effects of hemispheric laterality on a forced-choice Span of Apprehension (SoA) task were investigated. Forty-eight adult schizophrenic inpatients were recruited. A control group of healthy subjects was put together using the matched-pairs method with age, gender, and education as control variables. SoA performance was determined separately for the left and right visual field (VF), respectively. No SoA group differences were found; in both groups, the hit percentage was higher in the right VF. However, in the schizophrenic group, the left VF performance showed significant negative correlations with psychopathologic symptoms (especially auditory verbal hallucinations). In a subsample of patients receiving atypical neuroleptic drugs, the daily dosage correlated negatively with left VF performance. In general, young subjects performed better than old subjects (both VFs), males performed better than females, and subjects with high education performed better than subjects with low education (right VF). PMID:11315513

  12. Effects of Photovoltaic Module Soiling on Glass Surface Resistance and Potential-Induced Degradation

    SciTech Connect

    Hacke, Peter; Burton, Patrick; Hendrickson, Alex; Spataru, Sergiu; Glick, Stephen; Terwilliger, Kent

    2015-06-14

    The sheet resistance of three soil types (Arizona road dust, soot, and sea salt) on glass were measured by the transmission line method as a function of relative humidity (RH) between 39% and 95% at 60 degrees C. Sea salt yielded a 3.5 orders of magnitude decrease in resistance on the glass surface when the RH was increased over this RH range. Arizona road dust showed reduced sheet resistance at lower RH, but with less humidity sensitivity over the range tested. The soot sample did not show significant resistivity change compared to the unsoiled control. Photovoltaic modules with sea salt on their faces were step-stressed between 25% and 95% RH at 60 degrees C applying -1000 V bias to the active cell circuit. Leakage current from the cell circuit to ground ranged between two and ten times higher than that of the unsoiled controls. Degradation rate of modules with salt on the surface increased with increasing RH and time.

  13. Do Photovoltaic Energy Systems Effect Residential Selling Prices? Results from a California Statewide Investigation.

    SciTech Connect

    Hoen, Ben; Cappers, Pete; Wiser, Ryan; Thayer, Mark

    2011-04-12

    An increasing number of homes in the U.S. have sold with photovoltaic (PV) energy systems installed at the time of sale, yet relatively little research exists that provides estimates of the marginal impacts of those PV systems on home sale prices. This research analyzes a large dataset of California homes that sold from 2000 through mid-2009 with PV installed. We find strong evidence that homes with PV systems sold for a premium over comparable homes without PV systems during this time frame. Estimates for this premium expressed in dollars per watt of installed PV range, from roughly $4 to $6.4/watt across the full dataset, to approximately $2.3/watt for new homes, to more than $6/watt for existing homes. A number of ideas for further research are suggested.

  14. Carbon Nanotube Effects on Electroluminescence and Photovoltaic Response in Conjugated Polymers

    SciTech Connect

    Xu, Zhihua; Wu, Yue; Hu, Bin; Ivanov, Ilia N; Geohegan, David B

    2005-01-01

    This letter reports the experimental results of enhanced electroluminescence (EL) and photovoltaic (PV) response upon doping single-wall carbon nanotubes (SWNTs) into conjugated polymer poly[2-methoxy-5-(2{prime}-ethylhexyloxy)-1, 4-phenylenevinylene] (MEHPPV) based on single-layer light-emitting diodes. We found that the dispersed SWNTs result in two processes: charge transport and exciton dissociation at the tube-chain interface in the SWNT/polymer composites. The detailed EL and PV studies indicate that low SWNT doping concentrations mainly improve the bipolar charge injection, leading to enhanced both reverse and forward EL with reduced threshold voltage. As the SWNT doping concentration continues to increase, the interfacial exciton dissociation becomes dominated, giving rise to an increased PV response. This SWNT concentration-dependent charge transport and exciton dissociation present a pathway to individually address the dual EL and PV functionalities of SWNT-doped polymer composites by controlling the doping level of the SWNTs.

  15. Templating effects in molecular growth of blended films for efficient small-molecule photovoltaics.

    PubMed

    Wang, Zhiping; Miyadera, Tetsuhiko; Yamanari, Toshihiro; Yoshida, Yuji

    2014-05-14

    A strategy to control the molecular growth of coevaporated zinc phthalocyanine (ZnPc) and fullerene (C60) blended films for efficient organic photovoltaic (OPV) cells was demonstrated. Introduction of a 2,5-bis(4-biphenylyl)-bithiophene (BP2T) film or a ZnPc film on BP2T as nanostructured templates not only results in phase-separated domains in blended films with clear interpenetrating networks but also improves the crystallinity of ZnPc domains, both of which enhance photocurrent generation and charge carrier transport. Such morphology is strongly associated with the molecular growth of the templating layers. Roughness and adhesion of the templating layers are of great importance for the molecular growth of the blended films and in turn for cell characteristics. By carefully regulating the molecular growth of the blended films, the power conversion efficiency was improved by 125%, from 1.85 to 4.15% under 1 sun. PMID:24712371

  16. Accelerated testing of metal foil tape joints and their effect of photovoltaic module reliability

    NASA Astrophysics Data System (ADS)

    Sorensen, N. Robert; Quintana, Michael A.; Puskar, Joseph D.; Lucero, Samuel J.

    2009-08-01

    A program is underway at Sandia National Laboratories to predict long-term reliability of photovoltaic (PV) systems. The vehicle for the reliability predictions is a Reliability Block Diagram (RBD), which models system behavior. Because this model is based mainly on field failure and repair times, it can be used to predict current reliability, but it cannot currently be used to accurately predict lifetime. In order to be truly predictive, physics-informed degradation processes and failure mechanisms need to be included in the model. This paper describes accelerated life testing of metal foil tapes used in thin-film PV modules, and how tape joint degradation, a possible failure mode, can be incorporated into the model.

  17. Effect of indium on photovoltaic property of n-ZnO/p-Si heterojunction device prepared using solution-synthesized ZnO nanowire film

    NASA Astrophysics Data System (ADS)

    Kathalingam, Adaikalam; Kim, Hyun-Seok; Park, Hyung-Moo; Valanarasu, Santiyagu; Mahalingam, Thaiyan

    2015-01-01

    Preparation of n-ZnO/p-Si heterostructures using solution-synthesized ZnO nanowire films and their photovoltaic characterization is reported. The solution-grown ZnO nanowire film is characterized using scanning electron microscope, electron dispersive x-ray, and optical absorption studies. Electrical and photovoltaic properties of the fabricated heterostructures are studied using e-beam-evaporated aluminum as metal contacts. In order to use transparent contact and to simultaneously collect the photogenerated carriers, sandwich-type solar cells were fabricated using ZnO nanorod films grown on p-silicon and indium tin oxide (ITO) coated glass as ITO/n-ZnO NR/p-Si. The electrical properties of these structures are analyzed from current-voltage (I-V) characteristics. ZnO nanowire film thickness-dependent photovoltaic properties are also studied. Indium metal was also deposited over the ZnO nanowires and its effects on the photovoltaic response of the devices were studied. The results demonstrated that all the samples exhibit a strong rectifying behavior indicating the diode nature of the devices. The sandwich-type ITO/n-ZnO NR/p-Si solar cells exhibit improved photovoltaic performance over the Al-metal-coated n-ZnO/p-Si structures. The indium deposition is found to show enhancement in photovoltaic behavior with a maximum open-circuit voltage (Voc) of 0.3 V and short-circuit current (Isc) of 70×10-6 A under ultraviolet light excitation.

  18. Photovoltaic cell with thin CS layer

    DOEpatents

    Jordan, John F.; Albright, Scot P.

    1994-01-18

    An improved photovoltaic panel and method of forming a photovoltaic panel are disclosed for producing a high efficiency CdS/CdTe photovoltaic cell. The photovoltaic panel of the present invention is initially formed with a substantially thick Cds layer, and the effective thickness of the CdS layer is substantially reduced during regrowth to both form larger diameter CdTe crystals and substantially reduce the effective thickness of the C This invention was made with Government support under Subcontract No. ZL-7-06031-3 awarded by the Department of Energy. The Government has certain rights in this invention.

  19. Effects of ventromedial and lateral hypothalamic stimulation on chemically-induced liver injury in rats

    SciTech Connect

    Iwai, M.; Shimazu, T.

    1988-01-01

    The effects of hypothalamic stimulation on experimental liver injury induced by carbon tetrachloride (CCL/sub 4/) or dimethylnitrosamine (DMN) were studied in rats, by measuring plasma alanine amino-transferase (ALT) activity as an index of acute liver injury. Electrical stimulation of the ventromedial hypothalamus (VHM) in CCl/sub 4/-treated rats caused a marked increase in plasma ALT activity, accompanied by a significant decrease in ALT activity in the liver, although CCl4 treatment alone had no significant effect on plasma ALT activity. A similar effect of VHM stimulation on plasma ALT activity was observed in rats treated with DMN, another hepatotoxic chemical. No such exaggerated effect of VMH stimulation on plasma ALT activity was observed after stimulation of the lateral hypothalamic area (LH). Surgical sympathetic denervation of the liver greatly suppressed the increase in plasma ALT activity after CCl/sub 4/ injection and VMH stimulation. Measurement of regional blood flow indicated that VMH stimulation did not produce a significant change in blood flow to the liver. These results suggest that the VMH is involved in the progress of chemically-induced liver injury through activation of the sympathetic nerve, possibly by affecting liver metabolism more than the blood flow change to the liver.

  20. The effect of the low Earth orbit environment on space solar cells: Results of the advanced photovoltaic experiment (S0014)

    NASA Technical Reports Server (NTRS)

    Brinker, David J.; Hickey, John R.

    1992-01-01

    The Advanced Photovoltaic Experiment (APEX), containing over 150 solar cells and sensors, was designed to generate laboratory reference standards as well as to explore the durability of a wide variety of space solar cells. Located on the leading edge of the Long Duration Exposure Facility (LDEF), APEX received the maximum possible dosage of atomic oxygen and ultraviolet radiation, as well as enormous numbers of impacts from micrometeoroids and debris. The effect of the low earth orbital (LEO) environment on the solar cells and materials of APEX will be discussed in this paper. The on-orbit performance of the solar cells, as well as a comparison of pre- and postflight laboratory performance measurements, will be presented.

  1. π-Conjugated Copolymers of Thiophene: Effect of Chain Architecture on the Physical and Optoelectronic Properties for Photovoltaic Applications

    NASA Astrophysics Data System (ADS)

    Amonoo, Jojo; Glynos, Emmanouil; Chen, Chelsea; Li, Anton; Locke, Jonas; McNeil, Anne; Green, Peter

    2012-02-01

    We found that polymer chain architecture strongly influences phase separation capabilities of the donor-acceptor blend in bulk heterojunction organic photovoltaic devices. Ni-catalyzed controlled polymerization was utilized to access new conjugated copolymers of 3-hexylthiophene and 3-(hexyloxy)methylthiophene, two donor polymers. Monomer sequence was controlled along the copolymer chain by the rate of addition of the comonomers, to achieve diblock, random and gradient copolymer chain architectures. This allowed us to study the effect of copolymer sequence of polythiophene based copolymer/[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) blend on the structure, nanoscale morphology and local charge transport properties using conductive and photoconductive atomic force microscopy. The gradient configuration showed the largest phase separation behavior with PCBM.

  2. Effects of the Financial Crisis on Photovoltaics: An Analysis of Changes in Market Forecasts from 2008 to 2009

    SciTech Connect

    Bartlett, J. E.; Margolis, R. M.; Jennings, C. E.

    2009-09-01

    To examine how the financial crisis has impacted expectations of photovoltaic production, demand and pricing over the next several years, we surveyed the market forecasts of industry analysts that had issued projections in 2008 and 2009. We find that the financial crisis has had a significant impact on the PV industry, primarily through increasing the cost and reducing the availability of investment into the sector. These effects have been more immediately experienced by PV installations than by production facilities, due to the different types and duration of investments, and thus PV demand has been reduced by a greater proportion than PV production. By reducing demand more than production, the financial crisis has accelerated previously expected PV overcapacity and resulting price declines.

  3. Heat treatment effects in Cu2S-CdS heterojunction photovoltaic cells. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Fahrenbruch, A. L.

    1973-01-01

    The optical and electronic properties of single crystal Cu2S-CdS photovoltaic cells were investigated. In these cells trapped charge near the interface which is manifested by a persistent increase in junction capacitance (the photocapacitance) plays a significant role in determining the carrier transport properties. It was found that the severe degradation in short-circuit current observed in heat-treated cells can be separated into two components: (1) a relatively small thermal component occurring on heat-treatment in the dark, and (2) a much larger degradation caused by exposure to light at room temperature. By a short additional heat-treatment above approximately 100 C the cell can be completely restored to its condition before the optically caused degradation with no effect on the depletion layer width.

  4. Event-related lateralized readiness potential correlates of the emotion-priming Simon effect.

    PubMed

    Shang, Qian; Fu, Huijian; Qiu, Wenwei; Ma, Qingguo

    2016-08-01

    The Simon effect indicates that the reaction time (RT) is shorter when the stimulus and response locations are congruent than when they are not. This study used a priming-target paradigm to explore the emotion-priming Simon effect with event-related potential techniques. The technique of residue iteration decomposition was employed to analyze the lateralized readiness potential (LRP) component, which contributed to disentangling the overlap between LRP and N2 central contralateral in the Simon task with horizontal stimulus-response arrangements. The behavioral result revealed significant Simon effect in RT. In the neural process, the Simon effect was reflected by both the stimulus-locked LRP (S-LRP) and the response-locked LRP (R-LRP), with the incongruent condition showing longer onset latency, larger Gratton-dip, and smaller negative-going deflection of S-LRP and smaller negative-going deflection of R-LRP. These findings suggest that the interference of irrelevant location information is located at the perceptual-encoding (indicated by S-LRP) and response-execution stages (indicated by R-LRP), providing evidence for both the perceptual-interference and response-interference accounts. However, the further linear regression result signaled that the Simon effect might be more closely related to the response-execution stage than the perceptual-encoding stage. In addition, the influence of emotion on the Simon effect was salient only in the incongruent condition, showing longer onset latency of S-LRP and larger Gratton-dip of R-LRP in the negative emotion-priming condition than in the neutral emotion-priming condition, which revealed that the emotional interference effect arose from the stages of perceptual encoding and early response execution only when the locations of a stimulus and the corresponding response were incongruent. PMID:26993492

  5. Photovoltaic solar concentrator

    SciTech Connect

    Nielson, Gregory N.; Cruz-Campa, Jose Luis; Okandan, Murat; Resnick, Paul J.; Sanchez, Carlos Anthony; Clews, Peggy J.; Gupta, Vipin P.

    2015-09-08

    A process including forming a photovoltaic solar cell on a substrate, the photovoltaic solar cell comprising an anchor positioned between the photovoltaic solar cell and the substrate to suspend the photovoltaic solar cell from the substrate. A surface of the photovoltaic solar cell opposite the substrate is attached to a receiving substrate. The receiving substrate may be bonded to the photovoltaic solar cell using an adhesive force or a metal connecting member. The photovoltaic solar cell is then detached from the substrate by lifting the receiving substrate having the photovoltaic solar cell attached thereto and severing the anchor connecting the photovoltaic solar cell to the substrate. Depending upon the type of receiving substrate used, the photovoltaic solar cell may be removed from the receiving substrate or remain on the receiving substrate for use in the final product.

  6. Photovoltaics: New opportunities for utilities

    SciTech Connect

    Not Available

    1991-07-01

    This publication presents information on photovoltaics. The following topics are discussed: Residential Photovoltaics: The New England Experience Builds Confidence in PV; Austin's 300-kW Photovoltaic Power Station: Evaluating the Breakeven Costs; Residential Photovoltaics: The Lessons Learned; Photovoltaics for Electric Utility Use; Least-Cost Planning: The Environmental Link; Photovoltaics in the Distribution System; Photovoltaic Systems for the Rural Consumer; The Issues of Utility-Intertied Photovoltaics; and Photovoltaics for Large-Scale Use: Costs Ready to Drop Again.

  7. An integrated lateral flow assay for effective DNA amplification and detection at the point of care.

    PubMed

    Choi, Jane Ru; Hu, Jie; Gong, Yan; Feng, Shangsheng; Wan Abas, Wan Abu Bakar; Pingguan-Murphy, Belinda; Xu, Feng

    2016-05-10

    Lateral flow assays (LFAs) have been extensively explored in nucleic acid testing (NAT) for medical diagnostics, food safety analysis and environmental monitoring. However, the amount of target nucleic acid in a raw sample is usually too low to be directly detected by LFAs, necessitating the process of amplification. Even though cost-effective paper-based amplification techniques have been introduced, they have always been separately performed from LFAs, hence increasing the risk of reagent loss and cross-contaminations. To date, integrating paper-based nucleic acid amplification into colorimetric LFA in a simple, portable and cost-effective manner has not been introduced. Herein, we developed an integrated LFA with the aid of a specially designed handheld battery-powered system for effective amplification and detection of targets in resource-poor settings. Interestingly, using the integrated paper-based loop-mediated isothermal amplification (LAMP)-LFA, we successfully performed highly sensitive and specific target detection, achieving a detection limit of as low as 3 × 10(3) copies of target DNA, which is comparable to the conventional tube-based LAMP-LFA in an unintegrated format. The device may serve in conjunction with a simple paper-based sample preparation to create a fully integrated paper-based sample-to-answer diagnostic device for point-of-care testing (POCT) in the near future. PMID:27010033

  8. First-principles calculation of the bulk photovoltaic effect in KNbO3 and (K,Ba)(Ni,Nb)O3 -δ

    NASA Astrophysics Data System (ADS)

    Wang, Fenggong; Rappe, Andrew M.

    2015-04-01

    The connection between noncentrosymmetric materials' structure, electronic structure, and bulk photovoltaic performance remains not well understood. In particular, it is still unclear which photovoltaic (PV) mechanisms are relevant for the recently demonstrated visible-light ferroelectric photovoltaic (K,Ba)(Ni,Nb)O3 -δ. In this paper, we study the bulk photovoltaic effect (BPVE) of (K,Ba)(Ni,Nb)O3 -δ and KNbO3 by calculating the shift current from first principles. The effects of structural phase, lattice distortion, oxygen vacancies, cation arrangement, composition, and strain on BPVE are systematically studied. We find that (K,Ba)(Ni,Nb)O3 -δ has a comparable shift current with that of the broadly explored BiFeO3, but for a much lower photon energy. In particular, the Glass coefficient of (K,Ba)(Ni,Nb)O5 in a simple layered structure can be as large as 12 times that of BiFeO3. Furthermore, the nature of the wavefunctions dictates the eventual shift current yield, which can be significantly affected and engineered by changing the O vacancy location, cation arrangement, and strain. This is not only helpful for understanding other PV mechanisms that relate to the motion of the photocurrent carriers, but also provides guidelines for the design and optimization of PV materials.

  9. US photovoltaic patents: 1991-1993

    NASA Astrophysics Data System (ADS)

    Pohle, L.

    1995-03-01

    This document contains US patents on terrestrial photovoltaic (PV) power applications, including systems, components, and materials as well as manufacturing and support functions. The patent entries in this document were issued from 1991 to 1993. The entries were located by searching USPA, the database of the US Patent Office. The final search retrieved all patents under the class 'Batteries, Thermoelectric and Photoelectric' and the subclasses 'Photoelectric,' 'Testing,' and 'Applications.' The search also located patents that contained the words 'photovoltaic(s)' or 'solar cell(s)' and their derivatives. After the initial list was compiled, most of the patents on the following subjects were excluded: space photovoltaic technology, use of the photovoltaic effect for detectors, and subjects only peripherally concerned with photovoltaic. Some patents on these three subjects were included when ft appeared that those inventions might be of use in terrestrial PV power technologies.

  10. US photovoltaic patents: 1991--1993

    SciTech Connect

    Pohle, L

    1995-03-01

    This document contains US patents on terrestrial photovoltaic (PV) power applications, including systems, components, and materials as well as manufacturing and support functions. The patent entries in this document were issued from 1991 to 1993. The entries were located by searching USPA, the database of the US Patent Office. The final search retrieved all patents under the class ``Batteries, Thermoelectric and Photoelectric`` and the subclasses ``Photoelectric,`` ``Testing,`` and ``Applications.`` The search also located patents that contained the words ``photovoltaic(s)`` or ``solar cell(s)`` and their derivatives. After the initial list was compiled, most of the patents on the following subjects were excluded: space photovoltaic technology, use of the photovoltaic effect for detectors, and subjects only peripherally concerned with photovoltaic. Some patents on these three subjects were included when ft appeared that those inventions might be of use in terrestrial PV power technologies.

  11. Comparison of two approaches for considering laterally varying density in topographic effect on satellite gravity gradiometric data

    NASA Astrophysics Data System (ADS)

    Eshagh, Mehdi

    2010-08-01

    The satellite gravity gradiometric data are influenced by laterally varying density in topographic masses, while in most of studies a constant density for the masses was considered. This assumption causes an error in estimating the topographic effect. This paper theoretically and numerically investigates the methods of Sjöberg as well as Novák and Grafarend to consider the laterally varying density for topographic masses in formulation of topographic potential in spherical harmonics.

  12. Photovoltaic cell

    SciTech Connect

    Jordan, J.F.; Lampkin, C.M.

    1981-12-08

    A photovoltaic cell has: an electrically conductive substrate, which may be glass having a film of conductive tin oxide; a first layer containing a suitable semiconductor, which layer has a first component film with an amorphous structure and a second component film with a polycrystalline structure; a second layer forming a heterojunction with the first layer; and suitable electrodes where the heterojunction is formed from a solution containing copper, the amorphous film component is superposed above an electrically conductive substrate to resist permeation of the copper-containing material to shorting electrical contact with the substrate. The penetration resistant amporphous layer permits a variety of processes to be used in forming the heterojunction with even very thin layers (1-6 mu thick) of underlying polycrystalline semi-conductor materials. In some embodiments, the amorphous-like structure may be formed by the addition of aluminum or zirconium compounds to a solution of cadmium salts sprayed over a heated substrate.

  13. Does hemispheric lateralization influence therapeutic effects of transcranial direct current stimulation?

    PubMed Central

    Kwon, Yong Hyun; Kang, Kyung Woo; Lee, Na Kyung; Son, Sung Min

    2016-01-01

    This study investigated the effect of transcranial direct current stimulation (tDCS) polarity depending on lateralized function of task property in normal individuals performing visuomotor and simple repetitive tasks. Thirty healthy participants with no neurological disorders were recruited to participate in this study. Participants were randomly allocated into active or control condition. For the active condition, tDCS intensity was 2 mA with stimulation applied for 15 minutes to the right hemisphere (tDCS condition). For the sham control, electrodes were placed in the same position, but the stimulator was turned off after 30 seconds (sham condition). The tapping and tracking task tests were performed before and after for both conditions. Univariate analysis revealed significant difference only in the tracking task. For direct comparison of both tasks within each group, the tracking task had significantly higher Z score than the tapping task in the tDCS group (P < 0.05). Thus, our study indicates that stimulation of the right hemisphere using tDCS can effectively improve visuomotor (tracking) task over simple repetitive (tapping) task. PMID:26981100

  14. Effects of Noninvasive Ventilation on Sleep Outcomes in Amyotrophic Lateral Sclerosis

    PubMed Central

    Katzberg, Hans D.; Selegiman, Adam; Guion, Lee; Yuan, Nancy; Cho, Sungho C.; Katz, Jonathan S.; Miller, Robert G.; So, Yuen T.

    2013-01-01

    Study Objectives: The objective was to study the effects on noninvasive ventilation on sleep outcomes in patient with ALS, specifically oxygenation and overall sleep quality. Methods: Patients with ALS who met criteria for initiation of NIV were studied with a series of 2 home PSG studies, one without NIV and a follow-up study while using NIV. Primary outcome was a change in the maximum overnight oxygen saturation; secondary outcomes included change in mean overnight oxygen saturation, apnea and hypopnea indexes, sleep latency, sleep efficiency, sleep arousals, and sleep architecture. Results: A total of 94 patients with ALS were screened for eligibility; 15 were enrolled; and 12 completed study procedures. Maximum overnight oxygen saturation improved by 7.0% (p = 0.01) and by 6.7% during REM sleep (p = 0.02) with NIV. Time spent below 90% oxygen saturation was also significant-ly better with NIV (30% vs 19%, p < 0.01), and there was trend for improvement in mean overnight saturation (1.5%, p = 0.06). Apnea index (3.7 to 0.7), hypopnea index (6.2 to 5.7), and apnea hypopnea index (9.8 to 6.3) did not significantly improve after introducing NIV. NIV had no effect on sleep efficiency (mean change 10%), arousal index (7 to 12), or sleep stage distribution (Friedman chi-squared = 0.40). Conclusions: NIV improved oxygenation but showed no significant effects on sleep efficiency, sleep arousals, restful sleep, or sleep architecture. The net impact of these changes for patients deserves further study in a larger group of ALS patients. Citation: Katzberg HD; Selegiman A; Guion L; Yuan N; Cho SC; Katz JS; Mller RG; So YT. Effects of noninvasive ventilation on sleep outcomes in amyotrophic lateral sclerosis. J Clin Sleep Med 2013;9(4):345-351. PMID:23585750

  15. Enhanced photovoltaic performance of ultrathin Si solar cells via semiconductor nanocrystal sensitization: energy transfer vs. optical coupling effects

    NASA Astrophysics Data System (ADS)

    Hoang, Son; Ashraf, Ahsan; Eisaman, Matthew D.; Nykypanchuk, Dmytro; Nam, Chang-Yong

    2016-03-01

    Excitonic energy transfer (ET) offers exciting opportunities for advances in optoelectronic devices such as solar cells. While recent experimental attempts have demonstrated its potential in both organic and inorganic photovoltaics (PVs), what remains to be addressed is quantitative understanding of how different ET modes contribute to PV performance and how ET contribution is differentiated from the classical optical coupling (OC) effects. In this study, we implement an ET scheme using a PV device platform, comprising CdSe/ZnS nanocrystal energy donor and 500 nm-thick ultrathin Si acceptor layers, and present the quantitative mechanistic description of how different ET modes, distinguished from the OC effects, increase the light absorption and PV efficiency. We find that nanocrystal sensitization enhances the short circuit current of ultrathin Si solar cells by up to 35%, of which the efficient ET, primarily driven by a long-range radiative mode, contributes to 38% of the total current enhancement. These results not only confirm the positive impact of ET but also provide a guideline for rationally combining the ET and OC effects for improved light harvesting in PV and other optoelectronic devices.Excitonic energy transfer (ET) offers exciting opportunities for advances in optoelectronic devices such as solar cells. While recent experimental attempts have demonstrated its potential in both organic and inorganic photovoltaics (PVs), what remains to be addressed is quantitative understanding of how different ET modes contribute to PV performance and how ET contribution is differentiated from the classical optical coupling (OC) effects. In this study, we implement an ET scheme using a PV device platform, comprising CdSe/ZnS nanocrystal energy donor and 500 nm-thick ultrathin Si acceptor layers, and present the quantitative mechanistic description of how different ET modes, distinguished from the OC effects, increase the light absorption and PV efficiency. We find that

  16. Soils of sinkholes: effects of slope aspect and lateral transport of sediments on soil variation

    NASA Astrophysics Data System (ADS)

    Smirnova, Maria; Tsibart, Anna; Abramova, Anna; Koshovskii, Timur; Gennadiev, Alexander

    2015-04-01

    Karst landscapes are highly fragile and particularly vulnerable to subsidence and soil erosion. In karst region there may be hundreds or even thousands of sinkholes and other karst landforms in a small area so that the flat surface is actually absent. The effect of slope aspect on karst landscapes are resulted in different amount of solar radiation and increase of moisture along slopes. In European Russia semiarid landscapes the wind transport of the snow resulted in addition moistening of the soil situated on the eastern slope of depressions. Our research is devoted to the investigation of soil catenas on the slopes of subsidence sinkhole in "Bogdo-Baskuntschak" natural reserve (semiarid landscape). It based on field research of 4 soil catenas situated on the slopes of eastern, northern, western and south exposures. The profile of the sinkhole is an inverted cone (elongated from west to east), slope length varies from 8 to 12 meters, slope gradient - between 40-55% (eastern slope is the shortest and steepest). The short slope length and soil diversity that the sinkholes provided are beneficial for investigation of slope aspect and effect of lateral transport on soil formation. The main feature of sinkhole soil cover is a considerable variety and their high complexity. The lateral transport of sediments resulted in dramatic changes of soil within catenas. Haplic calcisols and arenosols calcaric, situated on the inter-sinkhole flat surface and upper parts of the slopes are substituted by cambisols and leptosols in the middle part of the slopes and colluvic regosols humic in the lower part of the slopes and sinkhole bottom. Soil formation and accumulation of sediments occur simultaneously and lead to the weak soil formation at the middle and lower sections of sinkhole side slopes. The thickness of humus horizon increases from the top to the bottom of sinkhole notably - from 8-12 cm on the upper and middle part of the slopes to 240 cm on the bottom of the sinkhole

  17. A cross-linguistic evaluation of script-specific effects on fMRI lateralization in late second language readers.

    PubMed

    Koyama, Maki S; Stein, John F; Stoodley, Catherine J; Hansen, Peter C

    2014-01-01

    Behavioral and neuroimaging studies have provided evidence that reading is strongly left lateralized, and the degree of this pattern of functional lateralization can be indicative of reading competence. However, it remains unclear whether functional lateralization differs between the first (L1) and second (L2) languages in bilingual L2 readers. This question is particularly important when the particular script, or orthography, learned by the L2 readers is markedly different from their L1 script. In this study, we quantified functional lateralization in brain regions involved in visual word recognition for participants' L1 and L2 scripts, with a particular focus on the effects of L1-L2 script differences in the visual complexity and orthographic depth of the script. Two different groups of late L2 learners participated in an fMRI experiment using a visual one-back matching task: L1 readers of Japanese who learnt to read alphabetic English and L1 readers of English who learnt to read both Japanese syllabic Kana and logographic Kanji. The results showed weaker leftward lateralization in the posterior lateral occipital complex (pLOC) for logographic Kanji compared with syllabic and alphabetic scripts in both L1 and L2 readers of Kanji. When both L1 and L2 scripts were non-logographic, where symbols are mapped onto sounds, functional lateralization did not significantly differ between L1 and L2 scripts in any region, in any group. Our findings indicate that weaker leftward lateralization for logographic reading reflects greater requirement of the right hemisphere for processing visually complex logographic Kanji symbols, irrespective of whether Kanji is the readers' L1 or L2, rather than characterizing additional cognitive efforts of L2 readers. Finally, brain-behavior analysis revealed that functional lateralization for L2 visual word processing predicted L2 reading competency. PMID:24795604

  18. Silicon Substrate Strained and Structured via Cavitation Effect for Photovoltaic and Biomedical Application.

    PubMed

    Savkina, Rada K; Gudymenko, Aleksandr I; Kladko, Vasyl P; Korchovyi, Andrii A; Nikolenko, Andrii S; Smirnov, Aleksey B; Stara, Tatyana R; Strelchuk, Viktor V

    2016-12-01

    A hybrid structure, which integrates the nanostructured silicon with a bio-active silicate, is fabricated using the method of MHz sonication in the cryogenic environment. Optical, atomic force, and scanning electron microscopy techniques as well as energy dispersive X-ray spectroscopy were used for the investigation of the morphology and chemical compound of the structured surface. Micro-Raman as well as X-ray diffraction, ellipsometry, and photovoltage spectroscopy was used for the obtained structures characterization. Ellipsometer measurements demonstrated the formation of the layer with the thicknesses ~700 nm and optical parameters closed to SiO2 compound with an additional top layer of the thicknesses ~15 nm and the refractive index ~1. Micro-Raman investigation detects an appearance of Ca-O local vibrational mode, and the stretching vibration of SiO4 chains characterized the wollastonite form of CaSiO3. A significant rise in the value and an expansion of the spectral range of the surface photovoltage for silicon structured via the megasonic processing was found. The concept of biocompatible photovoltaic cell on the base of Si\\CaSiO3 structure for the application in bioelectronics was proposed. PMID:27067731

  19. Effect of electron acceptor structure on stability and efficiency in polymer photovoltaics: a library approach

    NASA Astrophysics Data System (ADS)

    Tro, Michael; Oparko, David; Lewis, Emma; Sarabia, Alexis; Giammona, Maxwell; Isaac, Justin; Adalsteinsson, Thorsteinn; McNelis, Brian; Barber, Richard

    2014-03-01

    A commonly studied polymer photovoltaic system is prepared using a mixture of poly[3-hexylthiophene] (P3HT) as the electron donor and [6,6]-Phenyl C61 butyric acid methyl ester (PCBM) as the electron acceptor. We have prepared a series of PCBM analogs, making a variety of fullerene esters using commercially available primary alcohols. The first studies involved attaching an eight- or eighteen-carbon chain in place of the single carbon in PCBM. Solar cells made from these compounds exhibited improved lifetimes, motivating further exploration in the domain of possible attachments. We have now created a small library of these acceptor compounds and blended them with P3HT to prepare and measure solar cells. We collect current-voltage data over hours or days for each sample under ambient air conditions. These data provide not only the standard figures of merit, but also reveal the time dependence of these values. We have already observed significant differences between fullerene esters that are very similar in structure. Support for this work provided by an SCU Sustainability Research Grant and an SCU IBM Faculty Research Grant

  20. Effects of Non-equilibrium Solidification on the Material Properties of Brick Silicon for Photovoltaics

    NASA Technical Reports Server (NTRS)

    Regnault, W. F.; Yoo, K. C.; Soltani, P. K.; Johnson, S. M.

    1984-01-01

    Silicon ingot growth technologies like the Ubiquitous Crystallization Process (UCP) are solidified within a shaping crucible. The rate at which heat can be lost from this crucible minus the rate at which heat is input from an external source determines the rate at which crystallization will occur. Occasionally, when the process parameters for solidification are exceeded, the normally large multi-centimeter grain size material assocated with the UCP will break down into regions containing extremely small, millimeter or less, grain size material. Accompanying this breakdown in grain growth is the development of so called sinuous grain boundaries. The breakdown in grain growth which results in this type of small grain structure with sinuous boundaries is usually associated with the rapid crystallization that would accompany a system failure. This suggests that there are limits to the growth velocity that one can obtain and still expect to produce material that would possess good photovoltaic properties. It is the purpose to determine the causes behind the breakdown of this material and what parameters will determine the best rates of solidification.

  1. Impurity photovoltaic effect with defect relaxation: Implications for low band gap semiconductors such as silicon

    NASA Astrophysics Data System (ADS)

    Brown, Andrew S.; Green, Martin A.

    2004-09-01

    The impurity photovoltaic solar cell can, in principle, increase the sunlight to electricity conversion efficiency of a conventional single junction solar cell by the introduction of optically active impurities or defects into the device. These "defects" ideally allow electrons to be excited from the valence band to the conduction band via the mid-gap defect level through the absorption of previously wasted sub-band-gap photons. In this work the maximum efficiency limits for such a device are calculated for the special case where the energy of the partly excited electron relaxes to a lower energy partly through the two-stage excitation process. This relaxation in energy by the electron when occupying the defect state is shown to give an efficiency improvement over the case where no defect relaxation occurs. In the case of silicon, an efficiency limit of 39.7% under the airmass 1.5G solar spectrum is obtained, compared to 33.0% when no defects are present and 30.5% when a defect is present but no relaxation is allowed.

  2. Maximum Theoretical Efficiency Limit of Photovoltaic Devices: Effect of Band Structure on Excited State Entropy.

    PubMed

    Osterloh, Frank E

    2014-10-01

    The Shockley-Queisser analysis provides a theoretical limit for the maximum energy conversion efficiency of single junction photovoltaic cells. But besides the semiconductor bandgap no other semiconductor properties are considered in the analysis. Here, we show that the maximum conversion efficiency is limited further by the excited state entropy of the semiconductors. The entropy loss can be estimated with the modified Sackur-Tetrode equation as a function of the curvature of the bands, the degeneracy of states near the band edges, the illumination intensity, the temperature, and the band gap. The application of the second law of thermodynamics to semiconductors provides a simple explanation for the observed high performance of group IV, III-V, and II-VI materials with strong covalent bonding and for the lower efficiency of transition metal oxides containing weakly interacting metal d orbitals. The model also predicts efficient energy conversion with quantum confined and molecular structures in the presence of a light harvesting mechanism. PMID:26278444

  3. Silicon Substrate Strained and Structured via Cavitation Effect for Photovoltaic and Biomedical Application

    NASA Astrophysics Data System (ADS)

    Savkina, Rada K.; Gudymenko, Aleksandr I.; Kladko, Vasyl P.; Korchovyi, Andrii A.; Nikolenko, Andrii S.; Smirnov, Aleksey B.; Stara, Tatyana R.; Strelchuk, Viktor V.

    2016-04-01

    A hybrid structure, which integrates the nanostructured silicon with a bio-active silicate, is fabricated using the method of MHz sonication in the cryogenic environment. Optical, atomic force, and scanning electron microscopy techniques as well as energy dispersive X-ray spectroscopy were used for the investigation of the morphology and chemical compound of the structured surface. Micro-Raman as well as X-ray diffraction, ellipsometry, and photovoltage spectroscopy was used for the obtained structures characterization. Ellipsometer measurements demonstrated the formation of the layer with the thicknesses ~700 nm and optical parameters closed to SiO2 compound with an additional top layer of the thicknesses ~15 nm and the refractive index ~1. Micro-Raman investigation detects an appearance of Ca-O local vibrational mode, and the stretching vibration of SiO4 chains characterized the wollastonite form of CaSiO3. A significant rise in the value and an expansion of the spectral range of the surface photovoltage for silicon structured via the megasonic processing was found. The concept of biocompatible photovoltaic cell on the base of Si/CaSiO3 structure for the application in bioelectronics was proposed.

  4. Photovoltaic panel support assembly

    SciTech Connect

    Barker, J.M.; Underwood, J.C.; Shingleton, J.

    1993-07-20

    A solar energy electrical power source is described comprising in combination at least two flat photovoltaic panels disposed side-by-side in co-planar relation with one another, a pivot shaft extending transversely across the panels, at least two supports spaced apart lengthwise of the pivot shaft, means for connecting the pivot shaft to the at least two supports, attachment means for connecting the at least two panels to the pivot shaft so that the panels can pivot about the longitudinal axis of the shaft, coupling means mechanically coupling all of the panels together so as to form a unified flat array, and selectively operable drive means for mechanically pivoting the unified flat array about the axis; wherein each of the flat photovoltaic panels comprises at least two modules each comprising a plurality of electrically interconnected photovoltaic cells, the at least two modules being aligned along a line extending at a right angle to the pivot shaft, and the coupling means comprises (a) an elongate member extending parallel to and spaced from the pivot shaft and (b) means for attaching the elongate member to the panels; and further wherein each flat photovoltaic panel comprises a unitary frame consisting of a pair of end frame members extending parallel to the pivot shaft, a pair of side frame members extending between and connected to the end frame members, and a pair of spaced apart cross frame members, with one of the two modules being embraced by and secured to the side frame members and a first one of each of the end and cross frame members, and the other of the two modules being embraced by and secured to the side frame members and the second one of each of the end and cross frame members, whereby the gap created by the spaced apart cross frame members allow air to pass between them in order to reduce the sail effect when the solar array is subjected to buffeting winds.

  5. Discomfort of seated persons exposed to low frequency lateral and roll oscillation: effect of seat cushion.

    PubMed

    Beard, George F; Griffin, Michael J

    2014-11-01

    The discomfort caused by lateral oscillation, roll oscillation, and fully roll-compensated lateral oscillation has been investigated at frequencies between 0.25 and 1.0 Hz when sitting on a rigid seat and when sitting on a compliant cushion, both without a backrest. Judgements of vibration discomfort and the transmission of lateral and roll oscillation through the seat cushion were obtained with 20 subjects. Relative to the rigid seat, the cushion increased lateral acceleration and roll oscillation at the lower frequencies and also increased discomfort during lateral oscillation (at frequencies less than 0.63 Hz), roll oscillation (at frequencies less than 0.4 Hz), and fully roll-compensated lateral oscillation (at frequencies between 0.315 and 0.5 Hz). The root-sums-of-squares of the frequency-weighted lateral and roll acceleration at the seat surface predicted the greater vibration discomfort when sitting on the cushion. The frequency-dependence of the predicted discomfort may be improved by adjusting the frequency weighting for roll acceleration at frequencies between 0.25 and 1.0 Hz. PMID:24947003

  6. Effect of lateral versus supine wedged position on development of spinal blockade and hypotension.

    PubMed

    Hartley, H; Seed, P T; Ashworth, H; Kubli, M; O'Sullivan, G; Reynolds, F

    2001-07-01

    Aortocaval compression may not be completely prevented by the supine wedged or tilted positions. It is commonly believed, however, that the unmodified full lateral position after induction of spinal anaesthesia might allow excessive spread of the block. We therefore compared baseline arterial pressures in the supine wedged, sitting, tilted and full lateral positions in 40 women who were about to undergo elective caesarean section. They were then given spinal anaesthesia in the left lateral position and randomised to be turned to the right lateral or the supine wedged position, after which speed of onset and spread of blockade to cold sensation were measured every 2 min for 10 min and mean arterial pressure and ephedrine requirement were recorded every minute for 20 min. Baseline mean arterial pressure was 9 mmHg (95% CI 3 to 14) lower in the left lateral (measured in the upper arm) than in the sitting position; those in the supine wedged and tilted positions were intermediate. Following spinal anaesthesia, hypotension (defined as a reading lateral group and showed less variability. There is therefore no reason to fear the unmodified lateral group position, which may offer better protection against hypotension. PMID:15321608

  7. Effects of Soluble Surfactant on Lateral Migration of a Bubble in a Shear Flow

    NASA Astrophysics Data System (ADS)

    Muradoglu, Metin; Tryggvason, Gretar

    2014-11-01

    Motivated by the recent experimental study of Takagi et al. (2008), direct numerical simulations are performed to examine effects of soluble surfactant on the lateral migration of a deformable bubble in a pressure-driven channel flow. The interfacial and bulk surfactant concentration evolution equations are solved fully coupled with the incompressible Navier-Stokes equations. A non-linear equation of state is used to relate interfacial surface tension to surfactant concentration at the interface. A multiscale method is developed to handle the mass exchange between the interface and bulk fluid at high Peclet numbers, using a boundary-layer approximation next to the bubble and a relatively coarse grid for the rest of the flow. It is found that the surfactant induced Marangoni stresses can dominate over the shear-induced lift force and thus alter the behavior of the bubble completely, i.e., the contaminated bubble drifts away from the channel wall and stabilizes at the center of the channel in contrast with the corresponding clean bubble that drifts toward the wall and stabilizes near the wall. The Scientific and Technical Research Council of Turkey (TUBITAK), Grant 112M181 and Turkish Academy of Sciences (TUBA).

  8. Effects of antiepileptics on lateral geniculate nucleus-kindled seizures in rats.

    PubMed

    Ishikawa, Takashi; Fujiwara, Akinori; Takechi, Kenshi; Kamei, Chiaki

    2009-04-01

    The present study was undertaken to clarify the characteristics of lateral geniculate nucleus (LGN) kindling in rats, especially the efficacies of antiepileptics, in comparison with those of amygdala (AMG) kindling. Daily electrical stimulation of the LGN led to the development of a generalized convulsion (kangaroo posture and falling back) in all subjects, similar to AMG kindling. The kindling response of the LGN differed from that of the AMG in a number of respects, that is, a high after-discharge (AD) threshold, a large number of stimulations for completion of kindling, and a different pattern of electroencephalogram (EEG) development. On the other hand, the oral administration of sodium valproate, carbamazepine, clobazam, or zonisamide caused dose-dependent inhibitions of both seizure stage and AD duration of LGN-kindled seizures, whereas ethosuximide had no significant effects. In addition, seizure stage was more potently inhibited than AD duration by these antiepileptics, particularly with clobazam. In conclusion, LGN kindling possesses characteristics that are different from AMG kindling. In addition, it was demonstrated that LGN kindling is a useful model, similar to other types of limbic system kindling, for the evaluation of antiepileptics. PMID:19346673

  9. The effects of parental depressive symptoms, appraisals, and physical punishment on later child externalizing behavior.

    PubMed

    Callender, Kevin A; Olson, Sheryl L; Choe, Daniel E; Sameroff, Arnold J

    2012-04-01

    Examined a cognitive-behavioral pathway by which depressive symptoms in mothers and fathers increase risk for later child externalizing problem behavior via parents' appraisals of child behavior and physical discipline. Participants were 245 children (118 girls) at risk for school-age conduct problems, and their parents and teachers. Children were approximately 3 years old at Time 1 (T1) and 5 ½ years old at Time 2 (T2). At T1, mothers and fathers reported their depressive symptoms, perceptions of their child's reciprocal affection and responsiveness, frequency of physical punishment, and child externalizing problems. Mothers, fathers, and teachers provided ratings of externalizing behavior at T2. Structural equation modeling revealed that parents' negative attributions mediated positive relations between their depressive symptoms and frequency of physical punishment for both fathers and mothers. More frequent physical punishment, in turn, predicted increased child externalizing behavior at T2. In future research, transactional mechanisms underlying effects of clinical depression on child conduct problems should be explored at multiple stages of development. For parents showing depressive symptoms, restructuring distorted perceptions about their children's behavior may be an important component of intervention programs. PMID:21947616

  10. Electrical stimulation of the lateral habenula produces an inhibitory effect on sucrose self-administration.

    PubMed

    Friedman, Alexander; Lax, Elad; Dikshtein, Yahav; Abraham, Lital; Flaumenhaft, Yakov; Sudai, Einav; Ben-Tzion, Moshe; Yadid, Gal

    2011-01-01

    The lateral habenula (LHb) plays a role in prediction of negative reinforcement, punishment and aversive responses. In the current study, we examined the role that the LHb plays in regulation of negative reward responses and aversion. First, we tested the effect of intervention in LHb activity on sucrose reinforcing behavior. An electrode was implanted into the LHb and rats were trained to self-administer sucrose (20%; 16 days) until at least three days of stable performance were achieved (as represented by the number of active lever presses in self-administration cages). Rats subsequently received deep brain stimulation (DBS) of the LHb, which significantly reduced sucrose self-administration levels. In contrast, lesion of the LHb increased sucrose-seeking behavior, as demonstrated by a delayed extinction response to substitution of sucrose with water. Furthermore, in a modified non-rewarding conditioned-place-preference paradigm, DBS of the LHb led to aversion to the context associated with stimulation of this brain region. We postulate that electrical stimulation of the LHb attenuates positive reward-associated reinforcement by natural substances. PMID:20955718

  11. Effects of cockpit lateral stick characteristics on handling qualities and pilot dynamics

    NASA Technical Reports Server (NTRS)

    Mitchell, David G.; Aponso, Bimal L.; Klyde, David H.

    1992-01-01

    This report presents the results of analysis of cockpit lateral control feel-system studies. Variations in feel-system natural frequency, damping, and command sensing reference (force and position) were investigated, in combination with variations in the aircraft response characteristics. The primary data for the report were obtained from a flight investigation conducted with a variable-stability airplane, with additional information taken from other flight experiments and ground-based simulations for both airplanes and helicopters . The study consisted of analysis of handling qualities ratings and extraction of open-loop, pilot-vehicle describing functions from sum-of-sines tracking data, including, for a limited subset of these data, the development of pilot models. The study confirms the findings of other investigators that the effects on pilot opinion of cockpit feel-system dynamics are not equivalent to a comparable level of added time delay, and until a more comprehensive set of criteria are developed, it is recommended that feel-system dynamics be considered a delay-inducing element in the aircraft response. The best correlation with time-delay requirements was found when the feel-system dynamics were included in the delay measurements, regardless of the command reference. This is a radical departure from past approaches.

  12. The Effects of Parental Depressive Symptoms, Appraisals, and Physical Punishment on Later Child Externalizing Behavior

    PubMed Central

    Callender, Kevin A.; Olson, Sheryl L.; Choe, Daniel E.; Sameroff, Arnold J.

    2014-01-01

    Examined a cognitive-behavioral pathway by which depressive symptoms in mothers and fathers increase risk for later child externalizing problem behavior via parents’ appraisals of child behavior and physical discipline. Participants were 245 children (118 girls) at risk for school-age conduct problems, and their parents and teachers. Children were approximately 3 years old at Time 1 (T1) and 5 ½ years old at Time 2 (T2). At T1, mothers and fathers reported their depressive symptoms, perceptions of their child’s reciprocal affection and responsiveness, frequency of physical punishment, and child externalizing problems. Mothers, fathers, and teachers provided ratings of externalizing behavior at T2. Structural equation modeling revealed that parents’ negative attributions mediated positive relations between their depressive symptoms and frequency of physical punishment for both fathers and mothers. More frequent physical punishment, in turn, predicted increased child externalizing behavior at T2. In future research, transactional mechanisms underlying effects of clinical depression on child conduct problems should be explored at multiple stages of development. For parents showing depressive symptoms, restructuring distorted perceptions about their children’s behavior may be an important component of intervention programs. PMID:21947616

  13. Effects of chronic methylphenidate in adolescence on later methylphenidate self-administration in rhesus monkeys.

    PubMed

    Martelle, Susan E; Porrino, Linda J; Nader, Michael A

    2013-09-01

    Many children diagnosed with attention deficit hyperactivity disorder are treated with methylphenidate (MPH), despite limited information on later vulnerability to drug abuse. A previous study in adolescent monkeys treated with MPH for 1 year did not indicate differences in acquisition to cocaine reinforcement compared with controls. The present study extended this characterization to include MPH self-administration. Adolescent male rhesus monkeys treated previously with a sustained-release formulation of MPH (beginning at ∼30 months old) and control monkeys (n=8/group) were used. All had previous experience of self-administering cocaine under a fixed-ratio 30 schedule of reinforcement. Responding was maintained by food (1.0-g banana-flavored pellets) and MPH (saline, 0.001-0.1 mg/kg/injection) was substituted for food for at least five consecutive sessions. MPH functioned as a reinforcer in all monkeys; there were no differences between groups in MPH self-administration. These findings extend earlier research with cocaine reinforcement showing that MPH treatment in adolescent monkeys does not increase future reinforcing effects of stimulant drugs. PMID:23903242

  14. Enrichment in puppyhood and its effects on later behavior of dogs.

    PubMed

    Hubrecht, R C

    1995-02-01

    Enrichment of the captive environment is becoming more common, but little is known about the consequences of early enrichment on later development. Sixty pups from the breeding colony at Pfizer UK were assigned either to a control group or to one of two groups which received enrichment between the ages of 5 to 14 weeks: 1) a group receiving extra human socialization or 2) a group provided with chewable items suspended in the pen and a length of plastic pipe within the pen. The dogs' behavior was observed after two changes in husbandry: at 15 weeks of age after being placed in same-sex groups of five and after removal from these groups to pair-housing in a laboratory block. Rawhide was the most popular of the tested items. The litters with toys spent an average 64% of their time interacting with them, indicating that, given the choice, pups will make extensive use of such items. Enrichment did not have any measurable effect on the development of stereotypes, but 6 to 11 months after enrichment, dogs given increased human socialization were slightly more approachable than dogs from the other groups. Male dogs from this group spent 37% more time than did controls at the front of the pen, sitting and monitoring the room, a behavior that could be interpreted as an attempt to seek human contact. Early enrichment is easy to achieve and can improve the quality of life for pups. PMID:7752619

  15. Effects of fixational saccades on response timing in macaque lateral geniculate nucleus.

    PubMed

    Saul, Alan B

    2010-11-01

    Even during active fixation, small eye movements persist that might be expected to interfere with vision. Numerous brain mechanisms probably contribute to discounting this jitter. Changes in the timing of responses in the visual thalamus associated with fixational saccades are considered in this study. Activity of single neurons in alert monkey lateral geniculate nucleus (LGN) was recorded during fixation while pseudorandom visual noise stimuli were presented. The position of the stimulus on the display monitor was adjusted based on eye position measurements to control for changes in retinal locations due to eye movements. A method for extracting nonstationary first-order response mechanisms was applied, so that changes around the times of saccades could be observed. Saccade-related changes were seen in both amplitude and timing of geniculate responses. Amplitudes were greatly reduced around saccades. Timing was retarded slightly during a window of about 200 ms around saccades. That is, responses became more sustained. These effects were found in both parvocellular and magnocellular neurons. Timing changes in LGN might play a role in maintaining cortical responses to visual stimuli in the presence of eye movements, compensating for the spatial shifts caused by saccades via these shifts in timing. PMID:20932359

  16. The effects of emitter-tied field plates on lateral PNP ionizing radiation response

    SciTech Connect

    Barnaby, H.J.; Schrimpf, R.D.; Cirba, C.R.; Pease, R.L.; Fleetwood, D.M.; Kosier, S.L.

    1998-03-01

    Radiation response comparisons of lateral PNP bipolar technologies reveal that device hardening may be achieved by extending the emitter contact over the active base. The emitter-tied field plate suppresses recombination of carriers with interface traps.

  17. The effectiveness of post-detoxication referrals: effects on later detoxication admissions, drunkenness and criminality.

    PubMed

    Smart, R G; Finley, J; Funston, R

    1977-05-01

    This study concerned the effectiveness of post-detoxication referrals to a variety of treatment facilities. The purpose was to discover (i) the proportion of men accepting referrals who actually arrived, (ii) the differences in outcome for patients attending an out-patient clinic, a halfway house, and a long-stay farm, (iii) the differences in outcomes for patients treated in one of the above facilities compared with those for similar patients not receiving treatment. In all, 114 male detoxication admissions were included. However, only 60% arrived, even when firm referrals were made. Those arriving and not arriving did not differ in social or demographic characteristics, nor did those who were referred to the various treatment facilities. However, the referral group had more detoxication admissions in the post-detoxication period. There were no post-treatment overall differences between all treated and untreated patients in detoxication admissions, arrests for drunkenness or criminal convictions. Refusals were more often successes than the treated or untreated groups but this was due to their better prognosis at intake. In general, the data provide little cause for optimism about the value of post-detoxication referrals. PMID:69522

  18. Silicon purification melting for photovoltaic applications

    SciTech Connect

    VAN DEN AVYLE,JAMES A.; HO,PAULINE; GEE,JAMES M.

    2000-04-01

    The availability of polysilicon feedstock has become a major issue for the photovoltaic (PV) industry in recent years. Most of the current polysilicon feedstock is derived from rejected material from the semiconductor industry. However, the reject material can become scarce and more expensive during periods of expansion in the integrated-circuit industry. Continued rapid expansion of the PV crystalline-silicon industry will eventually require a dedicated supply of polysilicon feedstock to produce solar cells at lower costs. The photovoltaic industry can accept a lower purity polysilicon feedstock (solar-grade) compared to the semiconductor industry. The purity requirements and potential production techniques for solar-grade polysilicon have been reviewed. One interesting process from previous research involves reactive gas blowing of the molten silicon charge. As an example, Dosaj et all reported a reduction of metal and boron impurities from silicon melts using reactive gas blowing with 0{sub 2} and Cl{sub 2}. The same authors later reassessed their data and the literature, and concluded that Cl{sub 2}and 0{sub 2}/Cl{sub 2} gas blowing are only effective for removing Al, Ca, and Mg from the silicon melt. Researchers from Kawasaki Steel Corp. reported removal of B and C from silicon melts using reactive gas blowing with an 0{sub 2}/Ar plasma torch. Processes that purify the silicon melt are believed to be potentially much lower cost compared to present production methods that purify gas species.

  19. An Analysis of the Effects of Residential Photovoltaic Energy Systems on Home Sales Prices in California

    SciTech Connect

    Hoen, Ben; Cappers, Peter; Wiser, Ryan; Thayer, Mark

    2011-04-19

    An increasing number of homes in the U.S. have sold with photovoltaic (PV) energy systems installed at the time of sale, yet relatively little research exists that estimates the marginal impacts of those PV systems on home sale prices. A clearer understanding of these possible impacts might influence the decisions of homeowners considering the installation of a PV system, homebuyers considering the purchase of a home with PV already installed, and new home builders considering including PV as an optional or standard product on their homes. This research analyzes a large dataset of California homes that sold from 2000 through mid-2009 with PV installed. It finds strong evidence that homes with PV systems sold for a premium over comparable homes without PV systems during this time frame. Estimates for this premium expressed in dollars per watt of installed PV range, on average, from roughly $4 to $5.5/watt across a large number of hedonic and repeat sales model specifications and robustness tests. When expressed as a ratio of the sales price premium of PV to estimated annual energy cost savings associated with PV, an average ratio of 14:1 to 19:1 can be calculated; these results are consistent with those of the more-extensive existing literature on the impact of energy efficiency on sales prices. When the data are split among new and existing homes, however, PV system premiums are markedly affected. New homes with PV show premiums of $2.3-2.6/watt, while existing homes with PV show premiums of more than $6/watt. Reasons for this discrepancy are suggested, yet further research is warranted. A number of other areas where future research would be useful are also highlighted.

  20. The Effects of a Lateral Wedge Insole on Knee and Ankle Joints During Slope Walking.

    PubMed

    Uto, Yuki; Maeda, Tetsuo; Kiyama, Ryoji; Kawada, Masayuki; Tokunaga, Ken; Ohwatashi, Akihiko; Fukudome, Kiyohiro; Ohshige, Tadasu; Yoshimoto, Yoichi; Yone, Kazunori

    2015-12-01

    The purpose of this study was to determine whether a lateral wedge insole reduces the external knee adduction moment during slope walking. Twenty young, healthy subjects participated in this study. Subjects walked up and down a slope using 2 different insoles: a control flat insole and a 7° lateral wedge insole. A three-dimensional motion analysis system and force plate were used to examine the knee adduction moment, the ankle valgus moment, and the moment arm of the ground reaction force to the knee joint center in the frontal plane. The lateral wedge insole significantly decreased the moment arm of the ground reaction force, resulting in a reduction of the knee adduction moment during slope walking, similar to level walking. The reduction ratio of knee adduction moment by the lateral wedge insole during the early stance of up-slope walking was larger than that of level walking. Conversely, the lateral wedge insole increased the ankle valgus moment during slope walking, especially during the early stance phase of up-slope walking. Clinicians should examine the utilization of a lateral wedge insole for knee osteoarthritis patients who perform inclined walking during daily activity, in consideration of the load on the ankle joint. PMID:26252560

  1. Effects of Lateral Heterogeneity and Power Law Rheology on Glacially Induced Surface Motion and Gravity Rate of Change

    NASA Astrophysics Data System (ADS)

    Wu, P.; Wang, H.; van der Wal, W.

    2006-12-01

    Modern geodetic measurements from GPS, satellite altimetry, tide-gauges, Satellite Laser Ranging (SLR) and space-borne gravimetry (such as GRACE) have been used to monitor global change. Since these measurements contain contributions from glacial isostatic adjustment (GIA) and other tectonic processes, they must be modeled and removed in order to observe current climate change. In the past, most GIA models assumed that the earth is laterally homogeneous and the rheology is linear. The aim of this paper is to investigate the effects of lateral heterogeneity and Power-Law rheology on GIA induced land uplift rate, horizontal velocities, relative sealevels, J-dot and the secular gravity rate of change in the southern part of Hudson Bay, which is detected by the GRACE mission. Here, GIA is modeled with a spherical, self-gravitating, compressible viscoelastic, laterally heterogeneous earth using the Finite-Element Method. The effect of gravitationally self-consistent sea levels in realistic oceans is also included. Lateral variations in mantle viscosities and lithospheric thickness are inferred from the seismic tomography model S20A using well known scaling relationships. Power-Law rheologies in the whole mantle or in combination with linear rheologies in the upper or lower mantle are also investigated. Both ICE-5G and ICE-4G deglaciation models are used to investigate their effect on the pattern of rebound. Preliminary results show that both lateral heterogeneity and power-law rheology have strong effects on the direction and magnitude of horizontal velocities. The effects of lateral heterogeneity and power-law rheology are also large enough to be detected in land uplift rate, relative sealevels, J-dot and gravity rate of change. Their implication on observing the effects of global warming will also be discussed.

  2. A comparison of the biomechanical effects of valgus knee braces and lateral wedged insoles in patients with knee osteoarthritis.

    PubMed

    Jones, Richard K; Nester, Christopher J; Richards, Jim D; Kim, Winston Y; Johnson, David S; Jari, Sanjiv; Laxton, Philip; Tyson, Sarah F

    2013-03-01

    Increases in the external knee adduction moment (EKAM) have been associated with increased mechanical load at the knee and progression of knee osteoarthritis. Valgus knee braces and lateral wedged insoles are common approaches to reducing this loading; however no study has directly compared the biomechanical and clinical effects of these two treatments in patients with medial tibiofemoral osteoarthritis. A cross-over randomised design was used where each intervention was worn by 28 patients for a two week period. Pre- and post-intervention gait kinematic/kinetic data and clinical outcomes were collected to evaluate the biomechanical and clinical effects on the knee joint. The valgus knee brace and the lateral wedged insole significantly increased walking speed, reduced the early stance EKAM by 7% and 12%, and the knee adduction angular impulse by 8.6 and 16.1% respectively. The lateral wedged insole significantly reduced the early stance EKAM compared to the valgus knee brace (p=0.001). The valgus knee brace significantly reduced the knee varus angle compared to the baseline and lateral wedged insole. Improvements in pain and function subscales were comparable for the valgus knee brace and lateral wedged insole. There were no significant differences between the two treatments in any of the clinical outcomes; however the lateral wedged insoles demonstrated greater levels of acceptance by patients. This is the first study to biomechanically compare these two treatments, and demonstrates that given the potential role of knee loading in osteoarthritis progression, that both treatments reduce this but lateral wedge insoles appear to have a greater effect. PMID:22920242

  3. Long term effects of high intensity laser therapy in lateral epicondylitis patients.

    PubMed

    Akkurt, Ekrem; Kucuksen, Sami; Yılmaz, Halim; Parlak, Selman; Sallı, Ali; Karaca, Gülten

    2016-02-01

    The objective of this study is to investigate short- and long-term effects of high-intensity laser therapy (HILT) in lateral epicondylitis (LE) patients. Thirty patients with LE diagnosis (23 unilateral and 7 bilateral in total 37 elbows) were treated using HILT. LE patients were evaluated before, right after, and 6 months following HILT intervention post-treatment using visual analogue scale for pain (VAS) during activity and resting. Disabilities of the Arm, Shoulder, and Hand (DASH) Score and hand grip strength test (HGST) were used. The participants of the present study were also evaluated using Short-Form 36 (SF-36) before and 6 months after the treatment. Out of the 30 patients, 8 were male and 22 female with a mean age of 47.2 ± 9.7. The activity and resting VAS, DASH, and HGST scores revealed statistically significant improvement (p = 0.001) following treatment. Whereas VAS activity, DASH, and HGST scores increased after treatment until post-treatment 6 months significantly (p = 0.001), VAS resting scores remained stable (p = 0.476). A statistically significant improvement was also evident in the physical and mental components of SF-36 scores following treatment until post-treatment 6 months compared to pre-treatment scores (p = 0.001). In conclusion, the results of the present study suggest that HILT is a reliable, safe, and effective treatment option in LE patients in the short and long term considering pain, functional status, and quality of life. PMID:26714978

  4. Laterality effects in motor learning by mental practice in right-handers.

    PubMed

    Gentili, R J; Papaxanthis, C

    2015-06-25

    Converging evidences suggest that mental movement simulation and actual movement production share similar neurocognitive and learning processes. Although a large body of data is available in the literature regarding mental states involving the dominant arm, examinations for the nondominant arm are sparse. Does mental training, through motor-imagery practice, with the dominant arm or the nondominant arm is equally efficient for motor learning? In the current study, we investigated laterality effects in motor learning by motor-imagery practice. Four groups of right-hander adults mentally and physically performed as fast and accurately as possible (speed/accuracy trade-off paradigm) successive reaching movements with their dominant or nondominant arm (physical-training-dominant-arm, mental-training-dominant-arm, physical-training-nondominant-arm, and mental-training-nondominant-arm groups). Movement time was recorded and analyzed before, during, and after the training sessions. We found that physical and mental practice had a positive effect on the motor performance (i.e., decrease in movement time) of both arms through similar learning process (i.e., similar exponential learning curves). However, movement time reduction in the posttest session was significantly higher after physical practice than motor-imagery practice for both arms. More importantly, motor-imagery practice with the dominant arm resulted in larger and more robust improvements in movement speed compared to motor-imagery practice with the nondominant arm. No such improvements were observed in the control group. Our results suggest a superiority of the dominant arm in motor learning by mental practice. We discussed these findings from the perspective of the internal models theory. PMID:25797464

  5. The effect of inertia and angular momentum of a fluid annulus on lateral transversal rotor vibrations

    NASA Astrophysics Data System (ADS)

    Jansson, Ida; Åkerstedt, Hans O.; Aidanpää, Jan-Olov; Lundström, T. Staffan

    2012-01-01

    An extensive amount of work exists on experimental and theoretical analysis of unsteady flow phenomena in hydraulic turbines. Still, resonance phenomena and self-excited vibrations of the rotor of hydropower machines are not considered as a major problem during normal operation conditions. Nevertheless, in development and research it is not sufficient to rely on earlier experience. An accurate predictive rotor model is crucial in risk assessment of rotor vibrations of hydraulic generator units. This paper discusses the effects of inertia and the rotational energy of the fluid in the turbine on lateral transversal shaft vibrations of hydraulic generator units. There is a lack of agreement among engineers upon how fluid inertia of the turbine should be included in rotor models. The rotational energy of the fluid has a potential risk of feeding self-excited vibrations. A fluid-rotor model is presented that captures the effect of inertia and angular momentum of a fluid annulus on vibrations of an inner rigid cylinder. The purpose of the model is to gain physical understanding of the phenomena at work and it is not applicable to specific turbines. The linearized equation of motion of the cylinder surrounded by a fluid annulus is solved for by one single complex equation. The constrained cylinder has two degrees of freedom in the plane perpendicular to its axis. By the assumption of irrotational cyclic flow, the fluid motion is described by a complex potential function. The motion of the cylinder is described by three parameters. Two surfaces are defined that splits the parameter space into regions with different qualitative behaviour. One surface defines the limit of stability whereas the other defines a limit when the eigenvalues have opposite signs or are both positive. The response to an external periodic rotating force is visualized by the magnitude of the inverse of the complex dynamic stiffness.

  6. Enhanced photovoltaic performance of ultrathin Si solar cells via semiconductor nanocrystal sensitization: energy transfer vs. optical coupling effects.

    PubMed

    Hoang, Son; Ashraf, Ahsan; Eisaman, Matthew D; Nykypanchuk, Dmytro; Nam, Chang-Yong

    2016-03-10

    Excitonic energy transfer (ET) offers exciting opportunities for advances in optoelectronic devices such as solar cells. While recent experimental attempts have demonstrated its potential in both organic and inorganic photovoltaics (PVs), what remains to be addressed is quantitative understanding of how different ET modes contribute to PV performance and how ET contribution is differentiated from the classical optical coupling (OC) effects. In this study, we implement an ET scheme using a PV device platform, comprising CdSe/ZnS nanocrystal energy donor and 500 nm-thick ultrathin Si acceptor layers, and present the quantitative mechanistic description of how different ET modes, distinguished from the OC effects, increase the light absorption and PV efficiency. We find that nanocrystal sensitization enhances the short circuit current of ultrathin Si solar cells by up to 35%, of which the efficient ET, primarily driven by a long-range radiative mode, contributes to 38% of the total current enhancement. These results not only confirm the positive impact of ET but also provide a guideline for rationally combining the ET and OC effects for improved light harvesting in PV and other optoelectronic devices. PMID:26677967

  7. Effect of diamagnetic barium substitution on magnetic and photovoltaic properties in multiferroic BiFeO3

    NASA Astrophysics Data System (ADS)

    Hung, C.-M.; Tu, C. S.; Xu, Z.-R.; Chang, L.-Y.; Schmidt, V. H.; Chien, R. R.; Chang, W. C.

    2014-05-01

    Spontaneous magnetization and photovoltaic (PV) effects have been measured in (Bi1-xBax)FeO3-δ ceramics for x = 0.05, 0.10, and 0.15. The substitution of Ba2+ ion in the A site of the perovskite unit cell can effectively enhance the ferromagnetic magnetization. The heterostructure of indium tin oxide (ITO) film/(Bi1-xBax)FeO3-δ ceramic/Au film exhibits significant PV effects under illumination of λ = 405 nm. The PV responses decrease with increasing Ba concentration. The maximum power-conversion efficiency in the ITO/(Bi0.95Ba0.5)FeO2.95/Au can reach 0.006%. A theoretical model based on optically excited current in the depletion region between ITO film and (Bi1-xBax)FeO3-δ ceramics is used to describe the I-V characteristic, open-circuit voltage (Voc), and short-circuit current density (Jsc) as a function of light intensity.

  8. Effect of diamagnetic barium substitution on magnetic and photovoltaic properties in multiferroic BiFeO{sub 3}

    SciTech Connect

    Hung, C.-M.; Tu, C. S.; Xu, Z.-R.; Chang, L.-Y.; Schmidt, V. H.; Chien, R. R.; Chang, W. C.

    2014-05-07

    Spontaneous magnetization and photovoltaic (PV) effects have been measured in (Bi{sub 1-x}Ba{sub x})FeO{sub 3-δ} ceramics for x = 0.05, 0.10, and 0.15. The substitution of Ba{sup 2+} ion in the A site of the perovskite unit cell can effectively enhance the ferromagnetic magnetization. The heterostructure of indium tin oxide (ITO) film/(Bi{sub 1-x}Ba{sub x})FeO{sub 3-δ} ceramic/Au film exhibits significant PV effects under illumination of λ = 405 nm. The PV responses decrease with increasing Ba concentration. The maximum power-conversion efficiency in the ITO/(Bi{sub 0.95}Ba{sub 0.5})FeO{sub 2.95}/Au can reach 0.006%. A theoretical model based on optically excited current in the depletion region between ITO film and (Bi{sub 1-x}Ba{sub x})FeO{sub 3-δ} ceramics is used to describe the I-V characteristic, open-circuit voltage (V{sub oc}), and short-circuit current density (J{sub sc}) as a function of light intensity.

  9. The effect of the low Earth orbit environment on space solar cells: Results of the Advanced Photovoltaic Experiment (S0014)

    NASA Technical Reports Server (NTRS)

    Brinker, David J.; Hickey, John R.; Scheiman, David A.

    1993-01-01

    The results of post-flight performance testing of the solar cells flown on the Advanced Photovoltaic Experiment are reported. Comparison of post-flight current-voltage characteristics with similar pre-flight data revealed little or no change in solar cell conversion efficiency, confirming the reliability and endurance of space photovoltaic cells. This finding is in agreement with the lack of significant physical changes in the solar cells despite nearly six years in the low Earth orbit environment.

  10. Photovoltaic cell

    SciTech Connect

    Jordan, J. F.; Lampkin, C. M.

    1981-02-03

    A photovoltaic cell is disclosed having an electrically conductive substrate, which may be glass having a film of conductive tin oxide. A first layer contains a suitable semiconductor, which layer has a first component film with an amorphous structure and a second component film with a polycrystalline structure a second layer forms a heterojunction with the first layer suitable electrodes are provided where the heterojunction is formed from a solution containing copper, and the amorphous film component is superposed above an electrically conductive substrate to resist permeation of the copper-containing material to shorting electrical contact with the substrate. The penetration resistant amorphous layer permits a variety of processes to be used in forming the heterojunction with even very thin layers (1-6 mu thick) of underlying polycrystalline semi-conductor materials. In some embodiments, the amorphous-like structure may be formed by the addition of aluminum or zirconium compounds to a solution of cadmium salts sprayed over a heated substrate.

  11. Tuning the photovoltaic effect of multiferroic CoFe2O4/Pb(Zr, Ti)O3 composite films by magnetic fields

    NASA Astrophysics Data System (ADS)

    Pan, Dan-Feng; Chen, Guang-Yi; Bi, Gui-Feng; Zhang, Hao; Liu, Jun-Ming; Wang, Guang-Hou; Wan, Jian-Guo

    2016-05-01

    The 0-3 type CoFe2O4-Pb(Zr,Ti)O3 (CFO-PZT) multiferroic composite films have been prepared by a sol-gel process and spin-coating technique. A confirmable photovoltaic effect is observed under ultraviolet light irradiation. Moreover, this photovoltaic effect can be tuned by external magnetic fields. The maximum magnetic modulation ratios of short-circuit current density and open-circuit voltage can reach as high as 13.7% and 12.8% upon the application of 6 kOe DC magnetic field. Through remnant polarization measurements under various magnetic fields and detailed analysis of the energy band structures, we elucidate the mechanism of tuning photovoltaic effect by magnetic fields and attribute it to the combination of two factors. One is the decreased ferroelectric-polarization-induced depolarization electric field and another is the band structure reconstruction at CFO-PZT interfaces, both of which are dominated by the magnetoelectric coupling via interfacial stress transferring at nanoscale. This work makes some attempts of coupling photo-induced effects with magnetoelectric effect in multiferroic materials and will widen the practical ranges of multiferroic-based applications.

  12. Shear reinforcement effect of reinforced concrete tie-columns on the lateral resistance of confined masonry walls

    NASA Astrophysics Data System (ADS)

    Bouhedja, Samir; Bourzam, Abdelkrim; Boukhaled, Ahmed; Nechnech, Ammar

    2016-06-01

    Tie-columns improve significantly the lateral resistance of masonry bearing walls against persistent, transient and accidental loads. The research work described herein has been carried out to assess the lateral resistance of confined masonry walls, where contribution of the masonry panel is evaluated according to material mechanics and tie-columns effect is estimated by a proposed analytical formulation based on a model reported on previously. This approach takes into account the effect of dowel support on the reaction of its adjacent shear reinforcement: the conditions for the various contributions of transverse reinforcements are better defined following a clear evaluation of the participation ratio of these reinforcements. Lateral resistances of confined masonry walls measured in full-scale tests and gleaned from the literature are compared and checked with resistances calculated using the present approach.

  13. Later-borns Don't Give Up: The Temporary Effects of Birth Order on European Earnings.

    PubMed

    Bertoni, Marco; Brunello, Giorgio

    2016-04-01

    The existing empirical evidence on the effects of birth order on wages does not distinguish between temporary and permanent effects. Using data from 11 European countries for males born between 1935 and 1956, we show that firstborns enjoy on average a 13.7 % premium in their entry wage compared with later-borns. This advantage, however, is short-lived and disappears 10 years after labor market entry. Although firstborns start with a better job, partially because of their higher education, later-borns quickly catch up by switching earlier and more frequently to better-paying jobs. We argue that a key factor driving our findings is that later-borns have lower risk aversion than firstborns. PMID:26884377

  14. Effects of ytterbium on electrical and optical properties of BCP/Ag/WO3 transparent electrode based organic photovoltaic cells

    NASA Astrophysics Data System (ADS)

    Oh, Il Soo; Ji, Chan Hyuk; Oh, Se Young

    2016-01-01

    This study introduces dielectric/metal/dielectric multilayers based on a WO3/Ag/WO3 (WAW) anode and Yb/BCP/Ag/WO3 (Yb/BAW) cathode for use in organic photovoltaic cells (OPVs). Here, the Yb/BCP hybrid multilayer provides an effective electron transport layer (ETL), while the Yb doping ensures that voltage loss due to interfacial band bending is effectively suppressed. Transparent OPVs produced with a structure of WAW/P3HT:PCBM/Yb/BAW are shown to exhibit a power conversion efficiency (PCE) of up to 2.42%, achieving a 65.4% fill factor (FF) under one sun irradiation. These results indicate that the use of Yb in transparent OPVs is vastly superior to other ETLs, as it improves the majority of critical parameters such as short circuit current (Jsc), fill factor (FF) and PCE. This is attributed to a decrease in the series resistance and increase in the shunt resistance, while an increase in electron mobility also helps to ensure faster sweep out. [Figure not available: see fulltext.

  15. The Photovoltaic Effect of CdS Quantum Dots Synthesized in Inverse Micelles and R-Phycoerythrin Tunnel Cavities.

    PubMed

    Bekasova, Olga D; Revina, Alexandra A; Kornienko, Ekaterina S; Kurganov, Boris I

    2015-06-01

    CdS quantum dots (CdS QDs) 4.3 nm in diameter synthesized in an AOT/isooctane/water microemulsion and in R-phycoerythrin tunnel cavities (3.5 × 6.0 nm) were analyzed for photoelectrochemical properties. The CdS QDs preparations were applied onto a platinum electrode to obtain solid films. Experiments were performed in a two-section vessel, with one section filled with ethanol and the other, with 3 M KCl. The sections were connected through an agar stopper. It was found that illumination of the films resulted in a change of the electrode potential. The magnitude of this change and the kinetics of the appearance and disappearance of the photopotential, i.e., the difference between the electrode potential on the light and in dark, depended on the nature of the QD shell. The photovoltaic effect of CdS QDs in R-phycoerythrin, compared to that of CdS QDs in AOT/isooctane micelles, is three to four times greater due to the photosensitizing action of R-phycoerythrin. The photosensitized effect was markedly higher than the photoelectric sensitivity of R-phycoerythrin and had the opposite polarity. Changes in the potential upon turning the light on and off could be observed repeatedly. PMID:25935221

  16. Calcium-doping effects on photovoltaic response and structure in multiferroic BiFeO3 ceramics

    NASA Astrophysics Data System (ADS)

    Tu, C. S.; Hung, C.-M.; Xu, Z.-R.; Schmidt, V. H.; Ting, Y.; Chien, R. R.; Peng, Y.-T.; Anthoninappen, J.

    2013-09-01

    Photovoltaic (PV) effects, power-conversion efficiencies, and structures have been systematically measured in (Bi1-xCax)FeO3-δ ceramics for x = 0.05, 0.10, and 0.15. The heterostructures of indium tin oxide (ITO) film/(Bi1-xCax)FeO3-δ ceramics/Au film exhibit significant PV effects under illumination of λ = 405 nm. The maximum power-conversion efficiency in the ITO/(Bi0.90Ca0.10)FeO2.95 (BFO10C)/Au can reach 0.0072%, which is larger than 0.0025% observed in the graphene/polycrystalline BFO/Pt films [Zang et al., Appl. Phys. Lett. 99, 132904 (2011)]. A theoretical model based on optically excited current in the depletion region between ITO film and Ca-doped BFO ceramics is used to describe the I-V characteristic, open-circuit voltage, and short-circuit current density as a function of illumination intensity. This work suggests that the Ca-substitution can reduce the rhombohedral distortion and stabilize the single-phase structure.

  17. Drift-Diffusion Modeling of the Effects of Structural Disorder and Carrier Mobility on the Performance of Organic Photovoltaic Devices

    NASA Astrophysics Data System (ADS)

    Finck, Benjamin Y.; Schwartz, Benjamin J.

    2015-09-01

    We probe the effects of structural disorder on the performance of organic photovoltaic (OPV) devices via drift-diffusion modeling. We utilize ensembles of spatially disordered one-dimensional mobility profiles to approximate the three-dimensional structural disorder present in actual devices. Each replica in our ensemble approximates one high-conductivity pathway through the three-dimensional network(s) present in a polymer-based bulk heterojunction solar cell, so that the ensemble-averaged behavior provides a good approximation to a full three-dimensional structurally disordered device. Our calculations show that the short-circuit current, fill factor, and power conversion efficiency of simulated devices are all negatively impacted by the inclusion of structural disorder, but that the open-circuit voltage is nearly impervious to structural defects. This is in contrast to energetic disorder, where previous studies found that spatial variation in the energy in OPV active layers causes a decrease in the open-circuit voltage. We also show that structural disorder causes the greatest detriment to device performance for feature sizes between 2 and 10 nm. Since this is on the same length scale as the fullerene crystallites in experimental devices, it suggests both that controlling structural disorder is critical to the performance of OPV devices and that the effects of structural disorder should be included in future drift-diffusion modeling studies of organic solar cells.

  18. Hydrogenated TiO{sub 2} film for enhancing photovoltaic properties of solar cells and self-sensitized effect

    SciTech Connect

    He, Hongcai; Yang, Kui; Wang, Ning Luo, Feifei; Chen, Haijun

    2013-12-07

    Hydrogenated TiO{sub 2} film was obtained by annealing TiO{sub 2} film at 350 °C for 2 h with hydrogen, and TiO{sub 2} films were prepared by screen printing on fluorine-doped tin oxide glass. Structural characterization by X-ray diffraction and electron microscopy did not show obvious difference between hydrogenated TiO{sub 2} film and pristine TiO{sub 2} film. Through optical and electrochemical characterization, the hydrogenated TiO{sub 2} film showed enhanced absorption and narrowed band gap, as well as reduced TiO{sub 2} surface impedance and dark current. As a result, an obviously enhanced photovoltaic effect was observed in the solar cell with hydrogenated TiO{sub 2} as photoanode without adding any dye due to the self-sensitized effect of hydrogenated TiO{sub 2} film, which excited electrons injecting internal conduction band of TiO{sub 2} to generate more photocurrent.

  19. Modulatory Effects of Attention on Lateral Inhibition in the Human Auditory Cortex.

    PubMed

    Engell, Alva; Junghöfer, Markus; Stein, Alwina; Lau, Pia; Wunderlich, Robert; Wollbrink, Andreas; Pantev, Christo

    2016-01-01

    Reduced neural processing of a tone is observed when it is presented after a sound whose spectral range closely frames the frequency of the tone. This observation might be explained by the mechanism of lateral inhibition (LI) due to inhibitory interneurons in the auditory system. So far, several characteristics of bottom up influences on LI have been identified, while the influence of top-down processes such as directed attention on LI has not been investigated. Hence, the study at hand aims at investigating the modulatory effects of focused attention on LI in the human auditory cortex. In the magnetoencephalograph, we present two types of masking sounds (white noise vs. withe noise passing through a notch filter centered at a specific frequency), followed by a test tone with a frequency corresponding to the center-frequency of the notch filter. Simultaneously, subjects were presented with visual input on a screen. To modulate the focus of attention, subjects were instructed to concentrate either on the auditory input or the visual stimuli. More specific, on one half of the trials, subjects were instructed to detect small deviations in loudness in the masking sounds while on the other half of the trials subjects were asked to detect target stimuli on the screen. The results revealed a reduction in neural activation due to LI, which was larger during auditory compared to visual focused attention. Attentional modulations of LI were observed in two post-N1m time intervals. These findings underline the robustness of reduced neural activation due to LI in the auditory cortex and point towards the important role of attention on the modulation of this mechanism in more evaluative processing stages. PMID:26901149

  20. Effects of Imposed Variable Rates of Lateral Subsidence on a Deltaic System

    NASA Astrophysics Data System (ADS)

    Kim, W.; Kopp, J.

    2012-12-01

    Fluviodeltaic systems exist on Earth often under complex tectonic conditions, thus creating a myriad of motivations to understand the deltaic landscape evolution associated with tectonic activity. We present results from a series of six experiments conducted in the Sediment Transport and Earth-surface Processes (STEP) basin facility at the University of Texas at Austin. The STEP basin has a dimension of 4-m long, 5-m wide, and 1.5-m deep, and contains a hinged table that acts as a subsiding basin basement, which can be raised or lowered to create many different subsidence patterns in combination with placement of the sediment source. We utilized the table to impose lateral basement tilting to examine the effects of spatially varying rates of subsidence on an evolving fluviodeltaic system. The hinge axis at the center of the basin maintained constant base level at the location and thus created a bisection of the evolving delta such that relative base level fall occurred on one side of the delta (uplift), while a relative base level rise occurred on the other side of the delta (subsidence). The differential relative base-level changes on both sides of the rotation axis were applied to each experiment with a different rate, and thus causing variations in the overall asymmetrical shoreline planform pattern. The slow-tilting runs resulted in stronger shoreline progradation in the relatively uplifted side of the basin due to the shallow water depth in front of the delta, and thus caused asymmetrical shoreline pattern. However during the fast-tilting runs, the dominant section of prograding shoreline shifted to the subsiding side of the basin because rapid tilting prevents progradation on the uplifted side and instead steer the channels in the direction of subsidence. The tectonically influenced fluvial processes organize into the unique deltaic coastal pattern, providing insight into the integration of small-scale processes and large-scale landform.

  1. Immediate Effects of Lumbopelvic Manipulation and Lateral Gluteal Kinesio Taping on Unilateral Patellofemoral Pain Syndrome

    PubMed Central

    Miller, Joseph; Westrick, Richard; Diebal, Angela; Marks, Christopher; Gerber, J. Parry

    2013-01-01

    Objectives: To determine the immediate effects of Kinesio taping directed to the hip and manipulation directed to the lumbopelvic region in individuals with unilateral patellofemoral pain syndrome (PFPS). Background: PFPS affects up to 25% of the general population. Despite the high prevalence, this condition is not clearly understood, as evidenced by the numerous proposed causes and recommended treatments. Notwithstanding, recent evidence suggests that treatments directed at the hip or spine may lead to beneficial results. Methods: A convenience sample of 18 participants (12 men and 6 women, 19.5 ± 1.15 years old) with unilateral PFPS was recruited. Participants were randomized by sex to 1 of 3 groups: Kinesio taping, manipulation, and control taping. The main outcome measures included the Y-balance test, squatting range of motion (ROM), and the Lower Extremity Functional Scale. Results: Compared with the lumbopelvic manipulation and control groups, those in the Kinesio taping group performed significantly better on the Y-balance test (F = 5.59, P = 0.02) and with squatting ROM (F = 3.93, P = 0.04). The Kinesio taping and lumbopelvic groups were also significantly better than the control (sham) group with double-leg squatting ROM performance 3 days later. Conclusion: Kinesio taping may facilitate gluteus medius activation and improve postural stability and a double-leg squat. Clinical Relevance: The improvement in affected limb reach and double-leg squatting ROM highlights the potential for Kinesio taping to improve gluteus medius activation. Lumbopelvic manipulation may also immediately improve rehabilitation programs for PFPS. PMID:24427391

  2. Modulatory Effects of Attention on Lateral Inhibition in the Human Auditory Cortex

    PubMed Central

    Engell, Alva; Junghöfer, Markus; Stein, Alwina; Lau, Pia; Wunderlich, Robert; Wollbrink, Andreas; Pantev, Christo

    2016-01-01

    Reduced neural processing of a tone is observed when it is presented after a sound whose spectral range closely frames the frequency of the tone. This observation might be explained by the mechanism of lateral inhibition (LI) due to inhibitory interneurons in the auditory system. So far, several characteristics of bottom up influences on LI have been identified, while the influence of top-down processes such as directed attention on LI has not been investigated. Hence, the study at hand aims at investigating the modulatory effects of focused attention on LI in the human auditory cortex. In the magnetoencephalograph, we present two types of masking sounds (white noise vs. withe noise passing through a notch filter centered at a specific frequency), followed by a test tone with a frequency corresponding to the center-frequency of the notch filter. Simultaneously, subjects were presented with visual input on a screen. To modulate the focus of attention, subjects were instructed to concentrate either on the auditory input or the visual stimuli. More specific, on one half of the trials, subjects were instructed to detect small deviations in loudness in the masking sounds while on the other half of the trials subjects were asked to detect target stimuli on the screen. The results revealed a reduction in neural activation due to LI, which was larger during auditory compared to visual focused attention. Attentional modulations of LI were observed in two post-N1m time intervals. These findings underline the robustness of reduced neural activation due to LI in the auditory cortex and point towards the important role of attention on the modulation of this mechanism in more evaluative processing stages. PMID:26901149

  3. Photovoltaic roof construction

    SciTech Connect

    Hawley, W.W.

    1980-02-26

    In a batten-seam roof construction employing at least one photovoltaic cell module, the electrical conduits employed with the at least one photovoltaic cell module are disposed primarily under the battens of the roof.

  4. Charge versus Energy Transfer Effects in High-Performance Perylene Diimide Photovoltaic Blend Films.

    PubMed

    Singh, Ranbir; Shivanna, Ravichandran; Iosifidis, Agathaggelos; Butt, Hans-Jürgen; Floudas, George; Narayan, K S; Keivanidis, Panagiotis E

    2015-11-11

    Perylene diimide (PDI)-based organic photovoltaic devices can potentially deliver high power conversion efficiency values provided the photon energy absorbed is utilized efficiently in charge transfer (CT) reactions instead of being consumed in nonradiative energy transfer (ET) steps. Hitherto, it remains unclear whether ET or CT primarily drives the photoluminescence (PL) quenching of the PDI excimer state in PDI-based blend films. Here, we affirm the key role of the thermally assisted PDI excimer diffusion and subsequent CT reaction in the process of PDI excimer PL deactivation. For our study we perform PL quenching experiments in the model PDI-based composite made of poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b;4,5-b']dithiophene-2,6-diyl-alt-(4-(2-ethylhexanoyl)-thieno[3,4-b]thiophene)-2-6-diyl] (PBDTTT-CT) polymeric donor mixed with the N,N'-bis(1-ethylpropyl)-perylene-3,4,9,10-tetracarboxylic diimide (PDI) acceptor. Despite the strong spectral overlap between the PDI excimer PL emission and UV-vis absorption of PBDTTT-CT, two main observations indicate that no significant ET component operates in the overall PL quenching: the PL intensity of the PDI excimer (i) increases with decreasing temperature and (ii) remains unaffected even in the presence of 10 wt % content of the PBDTTT-CT quencher. Temperature-dependent wide-angle X-ray scattering experiments further indicate that nonradiative resonance ET is highly improbable due to the large size of PDI domains. The dominance of the CT over the ET process is verified by the high performance of devices with an optimum composition of 30:70 PBDTTT-CT:PDI. By adding 0.4 vol % of 1,8-diiodooctane we verify the plasticization of the polymer side chains that balances the charge transport properties of the PBDTTT-CT:PDI composite and results in additional improvement in the device efficiency. The temperature-dependent spectral width of the PDI excimer PL band suggests the presence of energetic disorder in the

  5. Thermionic photovoltaic energy converter

    NASA Technical Reports Server (NTRS)

    Chubb, D. L. (Inventor)

    1985-01-01

    A thermionic photovoltaic energy conversion device comprises a thermionic diode mounted within a hollow tubular photovoltaic converter. The thermionic diode maintains a cesium discharge for producing excited atoms that emit line radiation in the wavelength region of 850 nm to 890 nm. The photovoltaic converter is a silicon or gallium arsenide photovoltaic cell having bandgap energies in this same wavelength region for optimum cell efficiency.

  6. Effects of lateral boundary condition resolution and update frequency on regional climate model predictions

    NASA Astrophysics Data System (ADS)

    Pankatz, Klaus; Kerkweg, Astrid

    2015-04-01

    The work presented is part of the joint project "DecReg" ("Regional decadal predictability") which is in turn part of the project "MiKlip" ("Decadal predictions"), an effort funded by the German Federal Ministry of Education and Research to improve decadal predictions on a global and regional scale. In MiKlip, one big question is if regional climate modeling shows "added value", i.e. to evaluate, if regional climate models (RCM) produce better results than the driving models. However, the scope of this study is to look more closely at the setup specific details of regional climate modeling. As regional models only simulate a small domain, they have to inherit information about the state of the atmosphere at their lateral boundaries from external data sets. There are many unresolved questions concerning the setup of lateral boundary conditions (LBC). External data sets come from global models or from global reanalysis data-sets. A temporal resolution of six hours is common for this kind of data. This is mainly due to the fact, that storage space is a limiting factor, especially for climate simulations. However, theoretically, the coupling frequency could be as high as the time step of the driving model. Meanwhile, it is unclear if a more frequent update of the LBCs has a significant effect on the climate in the domain of the RCM. The first study examines how the RCM reacts to a higher update frequency. The study is based on a 30 year time slice experiment for three update frequencies of the LBC, namely six hours, one hour and six minutes. The evaluation of means, standard deviations and statistics of the climate in the regional domain shows only small deviations, some statistically significant though, of 2m temperature, sea level pressure and precipitation. The second part of the first study assesses parameters linked to cyclone activity, which is affected by the LBC update frequency. Differences in track density and strength are found when comparing the simulations

  7. Amorphous silicon photovoltaic devices

    SciTech Connect

    Carlson, David E.; Lin, Guang H.; Ganguly, Gautam

    2004-08-31

    This invention is a photovoltaic device comprising an intrinsic or i-layer of amorphous silicon and where the photovoltaic device is more efficient at converting light energy to electric energy at high operating temperatures than at low operating temperatures. The photovoltaic devices of this invention are suitable for use in high temperature operating environments.

  8. Photovoltaic device and method

    DOEpatents

    Cleereman, Robert J; Lesniak, Michael J; Keenihan, James R; Langmaid, Joe A; Gaston, Ryan; Eurich, Gerald K; Boven, Michelle L

    2015-01-27

    The present invention is premised upon an improved photovoltaic device ("PVD") and method of use, more particularly to an improved photovoltaic device with an integral locator and electrical terminal mechanism for transferring current to or from the improved photovoltaic device and the use as a system.

  9. Photovoltaic device and method

    SciTech Connect

    Cleereman, Robert; Lesniak, Michael J.; Keenihan, James R.; Langmaid, Joe A.; Gaston, Ryan; Eurich, Gerald K.; Boven, Michelle L.

    2015-11-24

    The present invention is premised upon an improved photovoltaic device ("PVD") and method of use, more particularly to an improved photovoltaic device with an integral locator and electrical terminal mechanism for transferring current to or from the improved photovoltaic device and the use as a system.

  10. Effect of lateral body position on transesophageal echocardiography images and the association with patient characteristics: A prospective observational study

    PubMed Central

    Mita, Norikatsu; Kuroda, Masataka; Saito, Shigeru; Miyoshi, Sohtaro

    2015-01-01

    Background: Changes in heart position are occasionally observed on the transesophageal echocardiography (TEE) image screen after changing the body position from supine to lateral, although the magnitude of change in cardiac position varies individually. We hypothesized that this variation is associated with certain patient characteristics and evaluated how lateral positioning affects visualization of the heart on TEE and whether the magnitude of change in the heart position correlates with patient characteristics. Methods: Fifty-three lung resection patients were enrolled. Two angle and two length parameters (ΔθTV, ΔθAP, ΔLTV, and ΔLAP) were defined to describe location change of the lateral tricuspid annulus and right ventricular apex on the TEE image between supine and lateral position. The correlation coefficients were calculated between these four parameters and patient characteristics, including age, body mass index (BMI), epicardial fat thickness, and pulmonary function variables. Results: The ΔθTV correlated positively and inversely with BMI in both right and left lateral patients (right: r = 0.6365, P = 0.0034; left: r = −0.6616, P < 0.0001, respectively). In left lateral patients, the ΔθTV correlated inversely with epicardial fat thickness (r = −0.4879, P = 0.0182), and the ΔLAP correlated positively with the forced vital capacity percent predicted (r = 0.5736, P = 0.0082). Conclusions: Lateral body positioning affects cardiac visualization on TEE, and the BMI, epicardial fat thickness, and pulmonary function moderate this effect. PMID:26139732

  11. The Effect of Modified Brostrom-Gould Repair for Lateral Ankle Instability on In Vivo Tibiotalar Kinematics

    PubMed Central

    Wainright, William B; Spritzer, Charles E.; Lee, Jun Young; Easley, Mark E.; DeOrio, James K.; Nunley, James A.; DeFrate, Louis E.

    2012-01-01

    Background Lateral ankle instability leads to an increased risk of tibiotalar joint osteoarthritis. Previous studies have found abnormal tibiotalar joint motions with lateral ankle instability that may contribute to this increased incidence of osteoarthritis, including increased anterior translation and internal rotation of the talus under weight-bearing loading. Surgical repairs for lateral ankle instability have shown good clinical results, but the effects of repair on in vivo ankle motion are not well understood. Hypothesis The modified Broström-Gould lateral ligament reconstruction decreases anterior translation and internal rotation of the talus under in vivo weight-bearing loading conditions. Study Design Controlled laboratory study. Methods Seven patients underwent modified Brostöm-Gould repair for unilateral lateral ankle instability. Ankle joint kinematics as a function of increasing body weight were studied with magnetic resonance imaging and biplanar fluoroscopy. Tibiotalar kinematics were measured in unstable ankles preoperatively and postoperatively at a mean follow-up of 12 months, as well as in the uninjured contralateral ankles of the same individuals. Results Surgical repair resulted in statistically significant decreases in anterior translation of the talus (0.9±0.3mm, p=0.018) at 100% bodyweight and internal rotation of the talus at 75% (2.6±0.8°, p=0.019) and 100% (2.7±0.8°, p=0.013) bodyweight compared to ankle kinematics measured before repair. No statistically significant differences were detected between repaired ankles and contralateral normal ankles. Conclusion The modified Broström-Gould repair improved the abnormal joint motion observed in patients with lateral ankle instability, decreasing anterior translation and internal rotation of the talus. Clinical Relevance Altered kinematics may contribute to the tibiotalar joint degeneration that occurs with chronic lateral ankle instability. The findings of the current study support

  12. Between- and within-Ear Congruency and Laterality Effects in an Auditory Semantic/Emotional Prosody Conflict Task

    ERIC Educational Resources Information Center

    Techentin, Cheryl; Voyer, Daniel; Klein, Raymond M.

    2009-01-01

    The present study investigated the influence of within- and between-ear congruency on interference and laterality effects in an auditory semantic/prosodic conflict task. Participants were presented dichotically with words (e.g., mad, sad, glad) pronounced in either congruent or incongruent emotional tones (e.g., angry, happy, or sad) and…

  13. Stimulus-Dominance Effects and Lateral Asymmetries for Language in Normal Subjects and in Patients with a Single Functional Hemisphere

    ERIC Educational Resources Information Center

    Di Stefano, Marirosa; Marano, Elena; Viti, Marzia

    2004-01-01

    The assessment of language laterality by the dichotic fused-words test may be impaired by interference effects revealed by the dominant report of one member of the stimuli-pair. Stimulus-dominance and ear asymmetry were evaluated in normal population (48 subjects of both sex and handedness) and in 2 patients with a single functional hemisphere.…

  14. Using the Hand Laterality Judgement Task to Assess Motor Imagery: A Study of Practice Effects in Repeated Measurements

    ERIC Educational Resources Information Center

    Boonstra, Anne M.; de Vries, Sjoerd J.; Veenstra, Evelien; Tepper, Marga; Feenstra, Wya; Otten, Egbert

    2012-01-01

    The aim of this study was to determine whether there is a practice effect on the Hand Laterality Judgement Task (HLJT). The HLJT task is a mental rotation task that can be used to assess motor imagery ability in stroke patients. Thirty-three healthy individuals performed the HLJT and two control tasks twice at a 3-week interval. Differences in the…

  15. Europe's space photovoltaics programme

    NASA Technical Reports Server (NTRS)

    Bogus, Klaus P.

    1994-01-01

    The current space PV (photovoltaic) technology development program of ESA is described. The program is closely coupled to the European space mission scenario for the next 10 year period and has as its main objective to make the most effective use of the limited resources available for technology in the present economical climate. This requires a well-balanced approach between concentration on very few options and keeping the competition alive if more than one promising technology exists. The paper describes ESA's main activities in the areas of solar array technology, solar cell technology, solar cell assembly technology, and special test and verification activities including the in-orbit demonstration of new technologies.

  16. Photovoltaic Manufacturing Technology

    NASA Astrophysics Data System (ADS)

    Easoz, J. R.; Herlocher, R. H.

    1991-12-01

    This report examines the cost-effective manufacture of dendritic-web-based photovoltaic modules. It explains how process changes can increase production and reduce manufacturing costs. Long-range benefits of these improved processes are also discussed. Problems are identified that could impede increasing production and reducing costs; approaches to solve these problems are presented. These approaches involve web growth throughput, cell efficiency, process yield, silicon use, process control, automation, and module efficiency. Also discussed are the benefits of bifacial module design, unique to the dendritic web process.

  17. Influence of Atmospheric Variations on Photovoltaic Performance and Modeling Their Effects for Days with Clear Skies: Preprint

    SciTech Connect

    Marion, B.

    2012-06-01

    Although variation in photovoltaic (PV) performance is predominantly influenced by clouds, performance variations also exist for days with clear skies with different amounts of atmospheric constituents that absorb and reflect different amounts of radiation as it passes through the earth's atmosphere. The extent of the attenuation is determined by the mass of air and the amounts of water vapor, aerosols, and ozone that constitute the atmosphere for a particular day and location. Because these constituents selectively absorb radiation of particular wavelengths, their impact on PV performance is sensitive to the spectral response of the PV device. The impact may be assessed by calculating the spectral mismatch correction. This approach was validated using PV module performance data at the National Renewable Energy Laboratory (NREL) for summer, fall, and winter days with clear skies. The standard deviation of daily efficiencies for single-crystal Si, a-Si/a-Si/a-Si:Ge, CdTe, and CIGS PV modules were reduced to 0.4% to 1.0% (relative) by correcting for spectral mismatch, temperature, and angle-of-incidence effects.

  18. Photovoltaic canopies: thermodynamics to achieve a sustainable systems approach to mitigate the urban heat island hysteresis lag effect

    NASA Astrophysics Data System (ADS)

    Golden, Jay S.

    2006-03-01

    At a time of greater attention to global climate change and increased costs of energy, our planet is rapidly urbanizing and transitioning regions from the natural rural vegetation to man-made urban engineered infrastructure. The anthropogenic-induced change has manifested itself in micro-scale and meso-scale increase in temperatures in comparison to adjacent rural regions which is known as the urban heat island effect ? Tu- r; (Oke 1987, Brazel 2003) and results in the increased need of electricity for mechanical cooling as well as various adverse environmental, social, and economic consequences for local and global communities (Golden 2004). Prior research has documented that between 29% and 45% of the urban fabric comprised paved surfaces to support mobility (Akbari et al. 1999). The increase in paved surfaces as a function of thermodynamics alters the urban energy budget due to changes in albedo, thermal mass as well as conduction, convection, and evapotranspiration. An emerging engineering option to reduce the significant role that surface pavements play in adding to the urban heat island is to capitalize on the capturing and shading of incident solar energy by means of utilization of photovoltaic panels to provide covered parking for this large portion of the urban fabric.

  19. New high Tc multiferroics KBiFe2O5 with narrow band gap and promising photovoltaic effect

    PubMed Central

    Zhang, Ganghua; Wu, Hui; Li, Guobao; Huang, Qingzhen; Yang, Chongyin; Huang, Fuqiang; Liao, Fuhui; Lin, Jianhua

    2013-01-01

    Intrinsic polarization of ferroelectrics (FE) helps separate photon-generated charge carriers thus enhances photovoltaic effects. However, traditional FE with transition-metal cations (M) of d0 electron in MO6 network typically has a band gap (Eg) exceeding 3.0 eV. Although a smaller Eg (2.6 eV) can be obtained in multiferroic BiFeO3, the value is still too high for optimal solar energy applications. Computational “materials genome” searches have predicted several exotic MO6 FE with Eg < 2.0 eV, all thus far unconfirmed because of synthesis difficulties. Here we report a new FE compound with MO4 tetrahedral network, KBiFe2O5, which features narrow Eg (1.6 eV), high Curie temperature (Tc ~ 780 K) and robust magnetic and photoelectric activities. The high photovoltage (8.8 V) and photocurrent density (15 μA/cm2) were obtained, which is comparable to the reported BiFeO3. This finding may open a new avenue to discovering and designing optimal FE compounds for solar energy applications. PMID:23405279

  20. Effect of Molecule–Surface Reaction Mechanism on the Electronic Characteristics and Photovoltaic Performance of Molecularly Modified Si

    PubMed Central

    2013-01-01

    We report on the passivation properties of molecularly modified, oxide-free Si(111) surfaces. The reaction of 1-alcohol with the H-passivated Si(111) surface can follow two possible paths, nucleophilic substitution (SN) and radical chain reaction (RCR), depending on adsorption conditions. Moderate heating leads to the SN reaction, whereas with UV irradiation RCR dominates, with SN as a secondary path. We show that the site-sensitive SN reaction leads to better electrical passivation, as indicated by smaller surface band bending and a longer lifetime of minority carriers. However, the surface-insensitive RCR reaction leads to more dense monolayers and, therefore, to much better chemical stability, with lasting protection of the Si surface against oxidation. Thus, our study reveals an inherent dissonance between electrical and chemical passivation. Alkoxy monolayers, formed under UV irradiation, benefit, though, from both chemical and electronic passivation because under these conditions both SN and RCR occur. This is reflected in longer minority carrier lifetimes, lower reverse currents in the dark, and improved photovoltaic performance, over what is obtained if only one of the mechanisms operates. These results show how chemical kinetics and reaction paths impact electronic properties at the device level. It further suggests an approach for effective passivation of other semiconductors. PMID:24205409

  1. Effect of annealing on graphene incorporated poly-(3-hexylthiophene):CuInS{sub 2} photovoltaic device

    SciTech Connect

    Kumari, Anita Dixit, Shiv Kumar; Singh, Inderpreet

    2014-10-15

    The effect of thermal annealing on the power conversion efficiency (PCE) of poly(3-hexylthiophene) (P3HT):CuInS{sub 2} quantum dot:graphene photovoltaic device has been studied by analyzing optical characteristics of composite films and electrical characteristics of the device with structure indium tin oxide/poly[ethylene dioxythiophene]:poly[styrene sulfonate] (ITO/PEDOT:PSS)/P3HT:CIS:graphene/LiF/aluminum. It was observed that after annealing at 120°C for 15 min a typical device containing 0.005 % w/w of graphene shows the best performance with a PCE of 1.3%, an open-circuit voltage of 0.44V, a short-circuit current density of 7.6 mA/cm{sup 2}, and a fill factor of 0.39. It is observed that the thermal annealing considerably enhances the efficiency of solar cells. However, an annealing at higher temperature such as at 140°C results in a decrease in the device efficiency.

  2. Simulation and Experimental Study on Effect of Phase Change Material Thickness to Reduce Temperature of Photovoltaic Panel

    NASA Astrophysics Data System (ADS)

    Indartono, Y. S.; Prakoso, S. D.; Suwono, A.; Zaini, I. N.; Fernaldi, B.

    2015-09-01

    Solar energy is promising renewable energy which can be applied in Indonesia. Average solar radiation in the country is 4.8 kWh/day/m2. Weakness of silicon-based photovoltaic (PV) is efficiency reduction caused by temperature increase. Many attempts have been done to reduce PV temperature. In previous study, palm oil, which is widely available in Indonesia, is suitable to be used as phase change material (PCM) to reduce PV temperature. In this study, thickness of aluminium rectangular-tube containing phase change material oil is varied. The tube is placed at back part of PV. Numerical and experimental study was done to evaluate the effect of tube thickness to the temperature reduction of the PV. Variation of tube thickness used in the experiment is 50.8mm, 76.2 mm, 101.6 mm. Both studies show that increase of PCM thickness reduces PV temperature. Higher PCM thickness cause large reduction on PV temperature. Simulation result shows there is an optimum thickness of the PCM which is applied to the PV.

  3. Effect of sulfur doped TiO2 on photovoltaic properties of dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Seo, Hyunwoong; Nam, Sang-Hun; Itagaki, Naho; Koga, Kazunori; Shiratani, Masaharu; Boo, Jin-Hyo

    2016-07-01

    In a dye-sensitized solar cell (DSC), a nano-porous semiconductor layer plays an important role in the performance. It determines open-circuit voltage and it affects the dye adsorption capacity and charge transfer, which are closely associated with photocurrent and overall performance. TiO2 is the most proper material for nano-porous layer since the first development of DSCs. This work focuses on the enhancement of TiO2 by doping. Sulfur (S) doping enhances charge transfer and the photoconversion of TiO2. Therefore, the increase in photocurrent and efficiency is expected by S doping. S is doped into TiO2 by hydrolysis method. The amount of S is varied and their photo-responses are verified. The most effective S doped TiO2 is applied to DSCs. Overall performance of DSC is enhanced by the addition of S doped TiO2. Especially, the photocurrent is much increased by the improvement on charge transfer, electron lifetime, and photo-conversion. The photovoltaic properties of DSCs are investigated with various ratios of undoped and S doped TiO2. Finally, a DSC based on undoped and S doped TiO2 ratio of 1:1 has the highest efficiency, better than that of a standard DSC based on undoped TiO2. [Figure not available: see fulltext.

  4. Dialkylthio Substitution: An Effective Method to Modulate the Molecular Energy Levels of 2D-BDT Photovoltaic Polymers.

    PubMed

    Yao, Huifeng; Zhang, Hao; Ye, Long; Zhao, Wenchao; Zhang, Shaoqing; Hou, Jianhui

    2016-02-17

    Dialkylthio-substituted thienyl-benzodithiophene (BDT-DST) was designed and synthesized as a building block to modulate the molecular levels of the conjugated polymers, and three copolymers named PDST-BDD, PDST-TT and PDST-DPP were prepared and applied in polymer solar cells (PSCs). Theoretical calculations and electrochemical cyclic voltammetry (CV) measurement suggested that the dialkylthio group could decrease the molecular energy levels of the resulting polymers distinctly. The open-circuit voltage (VOC) of PSC devices based on PDST-BDD, PDST-TT, and PDST-DPP are as high as 1.0, 0.98, and 0.88 V, respectively, which are ∼0.15 V higher than those of the corresponding alky-substituted analogues. Moreover, the influence of the dialkylthio group on the absorption spectra, crystalline properties, hole mobilities, and blend morphologies of the polymers was also investigated. The results indicate that the dialkythio substitution is an effective method to modulate the molecular energy levels and that the BDT-DST unit has potential for constructing high-efficiency photovoltaic polymers. PMID:26359953

  5. The Effects of Parental Depressive Symptoms, Appraisals, and Physical Punishment on Later Child Externalizing Behavior

    ERIC Educational Resources Information Center

    Callender, Kevin A.; Olson, Sheryl L.; Choe, Daniel E.; Sameroff, Arnold J.

    2012-01-01

    Examined a cognitive-behavioral pathway by which depressive symptoms in mothers and fathers increase risk for later child externalizing problem behavior via parents' appraisals of child behavior and physical discipline. Participants were 245 children (118 girls) at risk for school-age conduct problems, and their parents and teachers. Children were…

  6. Discomfort of seated persons exposed to low frequency lateral and roll oscillation: Effect of backrest height.

    PubMed

    Beard, George F; Griffin, Michael J

    2016-05-01

    Backrests influence the comfort of seated people. With 21 subjects sitting with three backrest heights (no backrest, short backrest, high backrest) discomfort caused by lateral, roll, and fully roll-compensated lateral oscillation was investigated at frequencies between 0.25 and 1.0 Hz. With lateral oscillation, the short backrest reduced discomfort at frequencies less than 0.63 Hz and the high backrest reduced discomfort at frequencies less than 1.0 Hz. With roll oscillation, the high backrest reduced discomfort at frequencies less than 0.63 Hz, but increased discomfort at 1.0 Hz. With fully roll-compensated lateral oscillation, the short backrest reduced discomfort at 0.4 Hz and the high backrest reduced discomfort at 0.5 and 0.63 Hz. As predicted by current standards, a backrest can increase discomfort caused by high frequencies of vibration. However, a backrest can reduce discomfort caused by low frequencies, with the benefit depending on the frequency and direction of oscillation and backrest height. PMID:26851464

  7. The effect of exercise on patellar tracking in lateral patellar compression syndrome.

    PubMed

    Doucette, S A; Goble, E M

    1992-01-01

    The influence of a physical therapy program on pain and patellar tracking was investigated clinically and radiologically with tangential views in 51 knees with lateral patellar compression syndrome. A pretest-posttest design was used to evaluate physical measurements of patellar alignment in subjects who had had patellofemoral pain for a minimum of 6 weeks. Eighty-four percent of the subjects were pain-free after an average of 8 weeks of rehabilitation or 11 physical therapy visits, with a mean quadriceps strength to total body weight ratio of 61% in women and 86% in men. The pretest-posttest difference in Merchant's congruence angle was significant at a probability of 0.0066 in the patients who were pain-free after exercise, demonstrating less lateral patellar tracking. The pretest-posttest difference in iliotibial band flexibility was significant at a probability of 0.0017, with the patients who were pain-free after exercise becoming more flexible. No significant differences were observed from before to after exercise in the patellofemoral index, Q angle, hamstring flexibility, thigh measurement, sclerotic subchondral bone, or sulcus angle. We were unable to predict which subjects would become pain-free with exercise by patellar position because the group that improved began more laterally tilted. The results of this study indicate that patellar tracking is improved with vastus medialis oblique strengthening, iliotibial band stretching, and joint mobility exercise in the majority of subjects with lateral patellar compression syndrome. PMID:1415887

  8. Remagnetization effects due to lateral displacement above a PMG on bulk HTS magnet

    NASA Astrophysics Data System (ADS)

    Liu, W.; Wang, J. S.; Ma, G. T.; Zheng, J.; Ren, J. F.; Li, L. L.; Yang, X. F.; Ye, C. Q.; Wang, S. Y.

    2012-12-01

    For a high-Tc superconducting (HTS) maglev system with large force requirements, the use of magnetized bulk high-Tc superconductor magnets (MBSCMs) is a good candidate because of its strong flux pinning ability and corresponding high trapped flux. Different from the rare-earth permanent magnet (PM), the trapped flux of a MBSCM is sustained by the supercurrent produced by a magnetizing process, so the trapped flux is sensitive to variations of the supercurrent. The lateral displacement of a MBSCM above a PM guideway (PMG) will provide disturbance of the applied field and then alter the supercurrent as a process of remagnetization. Different magnetization histories will bring different remagnetization characteristics and consequently diverse levitation performances for a MBSCM during the lateral displacements. When the MBSCMs are applied into the HTS maglev system, the influence of lateral displacements on levitation performance should be taken into consideration. This article investigates the remagnetization characteristics of a MBSCM when it is subject to the lateral displacements above a PMG with different trapped magnetic flux and opposite magnetization polarities. Relevant analyses about the internal supercurrent configuration based on the critical state model are also included to better understand the remagnetization characteristic of a MBSCM.

  9. Testing and Feedback Effects on Front-End Control over Later Retrieval

    ERIC Educational Resources Information Center

    Thomas, Ruthann C.; McDaniel, Mark A.

    2013-01-01

    In 2 experiments, we explored differences in cognitive control at retrieval on a final test to better understand the mechanisms underlying the powerful boost in recall of previously tested information. Memory retrieval can be enhanced by front-end control processes that regulate the scope of retrieval or by later processes that monitor retrieval…

  10. The effect of the aquatic contaminants bisphenol-A and PCB-95 on the zebrafish lateral line.

    PubMed

    Hayashi, Lauren; Sheth, Meghal; Young, Alexander; Kruger, Matthew; Wayman, Gary A; Coffin, Allison B

    2015-01-01

    Environmental toxicants such as bisphenol-A (BPA) and polychlorinated biphenyls (PCBs) are prevalent in our water supply, soil, and many food products and can profoundly affect the central nervous system. Both BPA and PCBs can disrupt endocrine signaling, which is important for auditory development and function, but the effect of these toxicants on the auditory periphery is not understood. In this study we investigated the effect of PCB-95 and BPA on lateral line development, function, and regeneration in larval zebrafish. The lateral line is a system of mechanosensory hair cells on the exterior of the fish that are homologous to the hair cells located in the mammalian inner ear. We found that PCB-95 had no effect on lateral line development or hair cell survival. BPA also did not affect lateral line development, but instead had a significant effect on both hair cell survival and regeneration. BPA-induced hair cell loss is both dose- and time-dependent, with concentrations of 1 μM or higher killing lateral line hair cells during a 24h exposure period. Pharmacologic manipulation experiments suggest that BPA kills hair cells via activation of oxidative stress pathways, similar to prior reports of BPA toxicity in other tissues. We also observed that hair cells killed with neomycin, a known ototoxin, failed to regenerate normally when BPA was present, suggesting that BPA in aquatic environments could impede innate regenerative responses in fishes. Collectively, these data demonstrate that BPA can have detrimental effects on sensory systems, both in aquatic life and perhaps in terrestrial organisms, including humans. PMID:25556122

  11. National Orange Show Photovoltaic Demonstration

    SciTech Connect

    Dan Jimenez Sheri Raborn, CPA; Tom Baker

    2008-03-31

    National Orange Show Photovoltaic Demonstration created a 400KW Photovoltaic self-generation plant at the National Orange Show Events Center (NOS). The NOS owns a 120-acre state fairground where it operates an events center and produces an annual citrus fair known as the Orange Show. The NOS governing board wanted to employ cost-saving programs for annual energy expenses. It is hoped the Photovoltaic program will result in overall savings for the NOS, help reduce the State's energy demands as relating to electrical power consumption, improve quality of life within the affected grid area as well as increase the energy efficiency of buildings at our venue. In addition, the potential to reduce operational expenses would have a tremendous effect on the ability of the NOS to service its community.

  12. Effect of Intensive Exercise in Early Adult Life on Telomere Length in Later Life in Men

    PubMed Central

    Laine, Merja K.; Eriksson, Johan G.; Kujala, Urho M.; Raj, Rahul; Kaprio, Jaakko; Bäckmand, Heli M.; Peltonen, Markku; Sarna, Seppo

    2015-01-01

    A career as an elite-class male athlete seems to improve metabolic heath in later life and is also associated with longer life expectancy. Telomere length is a biomarker of biological cellular ageing and could thus predict morbidity and mortality. The main aim of this study was to assess the association between vigorous elite-class physical activity during young adulthood on later life leukocyte telomere length (LTL). The study participants consist of former male Finnish elite athletes (n = 392) and their age-matched controls (n = 207). Relative telomere length was determined from peripheral blood leukocytes by quantitative real-time polymerase chain reaction. Volume of leisure-time physical activity (LTPA) was self-reported and expressed in metabolic equivalent hours. No significant difference in mean age-adjusted LTL in late life (p = 0.845) was observed when comparing former male elite athletes and their age-matched controls. Current volume of LTPA had no marked influence on mean age-adjusted LTL (p for trend 0.788). LTL was inversely associated with age (p = 0.004).Our study findings suggest that a former elite athlete career is not associated with LTL later in life. Key points A career as an elite-class athlete is associated with improved metabolic health in late life and is associated with longer life expectancy. A career as an elite-class athlete during young adulthood was not associated with leukocyte telomere length in later life. Current volume of leisure-time physical activity did not influence telomere length in later life. PMID:25983570

  13. Basic photovoltaic principles and methods

    SciTech Connect

    Hersch, P.; Zweibel, K.

    1982-02-01

    This book presents a nonmathematical explanation of the theory and design of photovoltaic (PV) solar cells and systems. The basic elements of PV are introduced: the photovoltaic effect, physical aspects of solar cell efficiency, the typical single-crystal silicon solar cell, advances in single-crystal silicon solar cells. This is followed by the designs of systems constructed from individual cells, including possible constructions for putting cells together and the equipment needed for a practical producer of electrical energy. The future of PV is then discussed. (LEW)

  14. Solar Glitter -- Microsystems Enabled Photovoltaics

    NASA Astrophysics Data System (ADS)

    Nielson, Gregory N.

    2012-02-01

    Many products have significantly benefitted from, or been enabled by, the ability to manufacture structures at an ever decreasing length scale. Obvious examples of this include integrated circuits, flat panel displays, micro-scale sensors, and LED lighting. These industries have benefited from length scale effects in terms of improved performance, reduced cost, or new functionality (or a combination of these). In a similar manner, we are working to take advantage of length scale effects that exist within solar photovoltaic (PV) systems. While this is a significant step away from traditional approaches to solar power systems, the benefits in terms of new functionality, improved performance, and reduced cost for solar power are compelling. We are exploring scale effects that result from the size of the solar cells within the system. We have developed unique cells of both crystalline silicon and III-V materials that are very thin (5-20 microns thick) and have very small lateral dimensions (on the order of hundreds of microns across). These cells minimize the amount of expensive semiconductor material required for the system, allow improved cell performance, and provide an expanded design space for both module and system concepts allowing optimized power output and reduced module and balance of system costs. Furthermore, the small size of the cells allows for unique high-efficiency, high-flexibility PV panels and new building-integrated PV options that are currently unavailable. These benefits provide a pathway for PV power to become cost competitive with grid power and allow unique power solutions independent of grid power.

  15. Effects of floor eggs on hatchability and later life performance in broiler chickens.

    PubMed

    van den Brand, H; Sosef, M P; Lourens, A; van Harn, J

    2016-05-01

    Two experiments were conducted in which effects of floor eggs, washed floor eggs, and clean nest eggs were investigated on incubation characteristics and performance in later life of broiler chickens. In both experiments, a young and an older breeder flock were used in a 3×2 factorial design during incubation. In the second experiment, male and female chickens were reared separately until d 35 of age in floor pens. During this grow out trial, an extra group was created in which chickens obtained from clean nest eggs were mixed with chickens obtained from floor eggs, meaning that grow out period was set up as a 4×2×2 factorial design with 4 egg types, 2 breeder ages, and 2 sexes. In both experiments, fertility and hatchability of fertile eggs were lower in floor and washed eggs than in clean nest eggs (hatchability: experiment 1: 74.4 vs. 70.6 vs. 92.6% for floor eggs, washed floor eggs and clean nest eggs, respectively, P<0.001; experiment 2: 78.3 vs. 81.7 vs. 90.2%, respectively, P<0.001). In experiment 2, BW at d 0 of chickens obtained from clean nest eggs was higher than that of chickens from floor eggs and washed floor eggs (41.5 vs. 40.4 and 40.3 g, respectively; P<0.001). This difference disappeared during the grow out period and was absent at slaughter age at d 35 of age. Feed intake (FI), feed conversion ratio (FCR), and mortality during the grow out period were not affected by egg type. Incidence and severity of hock burns and footpad dermatitis were not affected by egg type or breeder age. Litter friability at d 35 of age tended to be lower in pens with chickens obtained from washed floor eggs compared to clean nest eggs. We conclude that incubation of floor eggs or washed floor eggs resulted in lower fertility and hatchability compared to clean nest eggs, but that performance during the grow out period was not affected. PMID:26908895

  16. Transparent ultraviolet photovoltaic cells.

    PubMed

    Yang, Xun; Shan, Chong-Xin; Lu, Ying-Jie; Xie, Xiu-Hua; Li, Bing-Hui; Wang, Shuang-Peng; Jiang, Ming-Ming; Shen, De-Zhen

    2016-02-15

    Photovoltaic cells have been fabricated from p-GaN/MgO/n-ZnO structures. The photovoltaic cells are transparent to visible light and can transform ultraviolet irradiation into electrical signals. The efficiency of the photovoltaic cells is 0.025% under simulated AM 1.5 illumination conditions, while it can reach 0.46% under UV illumination. By connecting several such photovoltaic cells in a series, light-emitting devices can be lighting. The photovoltaic cells reported in this Letter may promise the applications in glass of buildings to prevent UV irradiation and produce power for household appliances in the future. PMID:26872163

  17. Photovoltaic fibers

    NASA Astrophysics Data System (ADS)

    Gaudiana, Russell; Eckert, Robert; Cardone, John; Ryan, James; Montello, Alan

    2006-08-01

    It was realized early in the history of Konarka that the ability to produce fibers that generate power from solar energy could be applied to a wide variety of applications where fabrics are utilized currently. These applications include personal items such as jackets, shirts and hats, to architectural uses such as awnings, tents, large covers for cars, trucks and even doomed stadiums, to indoor furnishings such as window blinds, shades and drapes. They may also be used as small fabric patches or fiber bundles for powering or recharging batteries in small sensors. Power generating fabrics for clothing is of particular interest to the military where they would be used in uniforms and body armor where portable power is vital to field operations. In strong sunlight these power generating fabrics could be used as a primary source of energy, or they can be used in either direct sunlight or low light conditions to recharge batteries. Early in 2002, Konarka performed a series of proof-of-concept experiments to demonstrate the feasibility of building a photovoltaic cell using dye-sensitized titania and electrolyte on a metal wire core. The approach taken was based on the sequential coating processes used in making fiber optics, namely, a fiber core, e.g., a metal wire serving as the primary electrode, is passed through a series of vertically aligned coating cups. Each of the cups contains a coating fluid that has a specific function in the photocell. A second wire, used as the counter electrode, is brought into the process prior to entering the final coating cup. The latter contains a photopolymerizable, transparent cladding which hardens when passed through a UV chamber. Upon exiting the UV chamber, the finished PV fiber is spooled. Two hundred of foot lengths of PV fiber have been made using this process. When the fiber is exposed to visible radiation, it generates electrical power. The best efficiency exhibited by these fibers is 6% with an average value in the 4

  18. Calculation of lateral-directional stability derivatives for wing-body combinations with and without jet-interaction effects

    NASA Technical Reports Server (NTRS)

    Lan, C. E.

    1977-01-01

    A theoretical method is presented for predicting the lateral-directional stability derivatives of wing-body combinations with or without the blowing jet effect. The fuselage effect is accounted for by the axial distribution of vortex multiplets. Comparison of the predicted results with experiments and other theoretical methods show good agreement for configurations without the blowing jet. More applicable experimental data with blowing jets are needed to establish the accuracy of the theory.

  19. Effect of top electrodes on photovoltaic properties of polycrystalline BiFeO3 based thin film capacitors

    NASA Astrophysics Data System (ADS)

    Chen, Bin; Li, Mi; Liu, Yiwei; Zuo, Zhenghu; Zhuge, Fei; Zhan, Qing-Feng; Li, Run-Wei

    2011-05-01

    We investigated capacitors based on polycrystalline narrow-band-gap BiFeO3 (BFO) thin films with different top electrodes. The photovoltaic response for the capacitor with a Sn-doped In2O3 (ITO) top electrode is about 25 times higher than that with a Au top electrode, which indicates that the electrode plays a key role in determining the photovoltaic response of ferroelectric thin film capacitors, as simulated by Qin et al (2009 Appl. Phys. Lett. 95 22912). The light-to-electricity photovoltaic efficiency for the ITO/polycrystalline BFO/Pt capacitor can reach 0.125%. Furthermore, under incident light of 450 µW cm - 2 and zero bias, the corresponding photocurrent varies from 0.2 to 200 pA, that is, almost a 1000-fold photoconductivity enhancement. Our experiments suggest that polycrystalline BFO films are promising materials for application in photo-sensitive and energy-related devices.

  20. The effect of lateral visual fixation and the direction of eye movements on heartbeat discrimination.

    PubMed

    Weisz, J; Balázs, L; Láng, E; Adám, G

    1990-09-01

    This study was undertaken to determine whether the asymmetrical activation of the two cerebral hemispheres affects the accuracy of heartbeat perception. Hemispheric preference--the tendency to activate one hemisphere rather than the other--was assessed by the directionality of conjugate lateral eye movements. Actual differential hemispheric activation was achieved by contralateral visual fixation. The results of 44 right-handed male subjects showed that right hemisphere preferent subjects ("left-movers") performed better on a heartbeat discrimination task than left hemisphere preferent subjects ("right-movers"). The direction of lateral visual fixation also influenced heartbeat discrimination: subjects fixating to the left were more accurate than those fixating to the right. PMID:2274615

  1. The dynamics of collagen uncrimping and lateral contraction in tendon and the effect of ionic concentration.

    PubMed

    Buckley, Mark R; Sarver, Joseph J; Freedman, Benjamin R; Soslowsky, Louis J

    2013-09-01

    Under tensile loading, tendon undergoes a number of unique structural changes that govern its mechanical response. For example, stretching a tendon is known to induce both the progressive "uncrimping" of wavy collagen fibrils and extensive lateral contraction mediated by fluid flow out of the tissue. However, it is not known whether these processes are interdependent. Moreover, the rate-dependence of collagen uncrimping and its contribution to tendon's viscoelastic mechanical properties are unknown. Therefore, the objective of this study was to (a) develop a methodology allowing for simultaneous measurement of crimp, stress, axial strain and lateral contraction in tendon under dynamic loading; (b) determine the interdependence of collagen uncrimping and lateral contraction by testing tendons in different swelling conditions; and (c) assess how the process of collagen uncrimping depends on loading rate. Murine flexor carpi ulnaris (FCU) tendons in varying ionic environments were dynamically stretched to a set strain level and imaged through a plane polariscope with the polarizer and analyzer at a fixed angle. Analysis of the resulting images allowed for direct measurement of the crimp frequency and indirect measurement of the tendon thickness. Our findings demonstrate that collagen uncrimping and lateral contraction can occur independently and interstitial fluid impacts tendon mechanics directly. Furthermore, tensile stress, transverse contraction and degree of collagen uncrimping were all rate-dependent, suggesting that collagen uncrimping plays a role in tendon's dynamic mechanical response. This study is the first to characterize the time-dependence of collagen uncrimping in tendon, and establishes structure-function relationships for healthy tendons that can be used to better understand and assess changes in tendon mechanics after disease or injury. PMID:23876711

  2. From unilateral to bilateral parkinsonism: Effects of lateralization on dyskinesias and associated molecular mechanisms.

    PubMed

    Marin, C; Bonastre, M; Mengod, G; Cortés, R; Rodríguez-Oroz, M C

    2015-10-01

    The mechanisms underlying lateralization and progression of motor symptoms from unilateral to bilateral in Parkinson's disease (PD) remain to be elucidated. In addition, the molecular mechanisms involved in levodopa-induced dyskinesias (LIDs) depending on lateralization and disease progression from unilaterally to bilateral have not been described yet. We investigated motor symptoms, LIDs and associated striatal molecular markers expression after unilateral left or right, and after a sequential bilateral 6-hydroxydopamine (6-OHDA)-induced nigrostriatal lesions in rats. Sequentially bilateral lesioned animals showed a bilateral increase in striatal preproenkephalin (PPE) mRNA without changes in pre-prodynorphin (PDyn) mRNA expression. The increase in dyskinesias when parkinsonism becomes bilateral was mostly due to an increase in orolingual dyskinesias associated to a increase in PDyn mRNA expression. Right lesion induces, or facilitates when first-done, a greater level of LIDs and an increase in striatal PPE and PDyn mRNAs in the second lesioned side. We describe a new striatal molecular pattern that appears when parkinsonism becomes bilateral and the relevance of the lateralization for the development of LIDs. PMID:26113400

  3. Effect of a lateral electric field on an off-center single dopant confined in a thin quantum disk

    NASA Astrophysics Data System (ADS)

    Dujardin, F.; Oukerroum, A.; Feddi, E.; Bosch Bailach, J.; Martínez-Pastor, J.; Zazi, M.

    2012-02-01

    The effect of a lateral electric field on a donor impurity confined in a thin quantum disk is studied theoretically in the framework of mass approximation and using the Ritz variational approach. We show that the binding energy depends on several parameters: the dot size, the position of the donor impurity, the lateral field strength, and its orientation relative to the axis containing the impurity. When the impurity is located at one edge and the electric field is oriented in the opposite direction, the binding energy is considerably reinforced due to the simultaneous additive effects of coulombic potential and electrostatic force. The competition between these effects modifies considerably the probability densities and allows a better comprehension of the binding energy variations. This interesting behavior can contribute to an better understanding of the experimental optical response.

  4. Characteristics of plasma plume and effect mechanism of lateral restraint during high power CO2 laser welding process

    NASA Astrophysics Data System (ADS)

    Wu, Yue; Cai, Yan; Sun, Dawei; Zhu, Junjie; Wu, Yixiong

    2014-12-01

    A novel lateral restraint method was proposed to suppress plasma plume of high power CO2 laser welding using a pair of copper blocks with cooling water. The plasma plume was observed with a high-speed camera, and its core zone and periphery zone were investigated based on the specific processing algorithm. With the specially designed shifting unit, the spectrum of plasma plume was scanned both in 1-D and 2-D mode. Based on the selected spectral lines, electron temperature and electron number density of plasma plume were calculated. The characteristics of plasma plume, as well as the restraint mechanism, were discussed both in 1-D and 2-D mode. Results showed that the cooling effect, blowing effect and the static pressure were enhanced by the lateral restraint, and the restraint effect of the near-wall low-temperature area limited the expansion of plasma plume greatly.

  5. Effects of design on cost of flat-plate solar photovoltaic arrays for terrestrial central station power applications

    NASA Technical Reports Server (NTRS)

    Tsou, P.; Stolte, W.

    1978-01-01

    The paper examines the impact of module and array designs on the balance-of-plant costs for flat-plate terrestrial central station power applications. Consideration is given to the following types of arrays: horizontal, tandem, augmented, tilt adjusted, and E-W tracking. The life-cycle cost of a 20-year plant life serves as the costing criteria for making design and cost tradeoffs. A tailored code of accounts is developed for determining consistent photovoltaic power plant costs and providing credible photovoltaic system cost baselines for flat-plate module and array designs by costing several varying array design approaches.

  6. Effect of Zinc Nitrate Concentration on the Optical and Morphological Properties of ZnO Nanorods for Photovoltaic Applications.

    PubMed

    Kim, Sung Jae; Anwar, M S; Heo, Si-Nae; Koo, Bon Heun

    2016-06-01

    We report the effect of zinc nitrate (ZN) concentration on the growth of zinc oxide (ZnO) nanorods and their optical and morphological properties. As prepared ZnO nanorods on glass substrate were characterized using field emission scanning electron microscopy (FE-SEM), ultra violet-visible (UV-Vis), Raman and Photo-luminescence (PL) spectroscopy. FE-SEM results show that the nanorods were obtained for the 0.033 and 0.053 M concentration of ZN. As the ZN concentration increased from 0.033 M to 0.053 M, the diameter of the nanorods was increased. It indicated that the diameter of the nanorods was affected by the ZN concentration. The Raman spectra of nanorods show only one peak at 438 cm(-1) corresponding to E2(high) high mode, which means that ZnO nanorods grown perpendicularly on the glass substrate, i.e., the ZnO nanorod arrays are highly c-axis oriented. Room-temperature PL spectrum of the as-grown ZnO nanorods reveals a near-band-edge (NBE) emission peak and defect induced green light emission. The green light emission band at -579 nm might be attributed to surface oxygen vacancies or defects. The UV-visible measurements reflect that the total transmittance for the as grown ZnO nanorods is over 80%. The simple technique presented in this study to grow ZnO nanorods on a glass substrate can be helpful for making the cost effective photovoltaic devices. PMID:27427680

  7. Flate-plate photovoltaic power systems handbook for Federal agencies

    NASA Technical Reports Server (NTRS)

    Cochrane, E. H.; Lawson, A. C.; Savage, C. H.

    1984-01-01

    The primary purpose is to provide a tool for personnel in Federal agencies to evaluate the viability of potential photovoltaic applications. A second objective is to provide descriptions of various photovoltaic systems installed by different Federal agencies under the Federal Photovoltaic Utilization Program so that other agencies may consider similar applications. A third objective is to share lessons learned to enable more effective procurement, design, installation, and operation of future photovoltaic systems. The intent is not to provide a complete handbook, but rather to provide a guide for Federal agency personnel with additional information incorporated by references. The steps to be followed in selecting, procuring, and installing a photovoltaic application are given.

  8. TiO2 photoanode sensitized with nanocrystalline Bi2S3: the effect of sensitization time and annealing on its photovoltaic performance

    NASA Astrophysics Data System (ADS)

    Kulkarni, Anil N.; Rajendra Prasad, M. B.; Pathan, Habib M.; Patil, Rajendra S.

    2016-04-01

    This work deals with the sensitization of the porous TiO2 films of thickness about 4 µm deposited on fluorine-doped tin oxide with nanocrystalline Bi2S3 for photovoltaic application. The sensitization was achieved for four different sensitization times employing chemical solution deposition with bismuth nitrate and sodium thiosulphate as precursors for Bi3+ and S2-, respectively. The unsensitized and sensitized photoelectrodes were characterized using X-ray diffractometry, scanning electron microscopy and diffused reflectance spectroscopy. XRD patterns show the signatures of both anatase TiO2 and orthorhombic Bi2S3 in the sensitized photoanodes. However, crystallinity of Bi2S3 increased with increase in sensitization time from 10 to 40 min. The temporal effect of sensitization and annealing on the photovoltaic performance of the solar cells fabricated using four different photoelectrodes was studied using the photocurrent density versus photovoltage curves. Annealing apparently improved the photovoltaic performance of photoanodes. The best performance was obtained for cell fabricated using annealed TiO2/Bi2S3 photoanode after 30 min sensitization time showing V oc ~ 0.37 mV, J sc ~ 0.52 mA/cm2, FF ~ 68 and 0.43 %.

  9. Solar Thermophotovoltaics: Combining Solar Thermal and Photovoltaics

    NASA Astrophysics Data System (ADS)

    Luque, Antonio

    2007-02-01

    An analysis of ideal solar converters from a thermodynamic point of view is presented that distinguishes between solar thermal and photovoltaic converters. The later do not have hot elements. Ideal solar thermophotovoltaic converters are also described as needing a Carnot machine for operation. The ideal solar cells can be such Carnot machine and therefore a solar thermophotovoltaic converter is a solar thermal converter whose engine is a solar cell. Once hot elements are accepted, several novel modalities of converters are described including thermophotonic converters, combined photovoltaic thermal converters and hot electron converters.

  10. Effects of humid heat exposure in later sleep segments on sleep stages and body temperature in humans

    NASA Astrophysics Data System (ADS)

    Okamoto-Mizuno, Kazue; Tsuzuki, Kazuyo; Mizuno, Koh

    2005-03-01

    This study sought to investigate the effects of humid heat exposure in later sleep segments on sleep stages and body temperature in humans. The subjects were eight healthy males, from whom informed consent had been obtained. The experiments were carried out under three different sets of conditions: a control climate [air temperature (Ta)=26°C, relative humidity (RH)=50%] (C); a humid heat climate (Ta=32°C, RH=80%) (H); and a humid heat exposure in later sleep segments (C for the first 3 h 45 min, followed by a 30-min transition to H, which was then maintained for the last 3 h 45 min) (C H). Electroencephalogram, EOG, and mental electromyogram, rectal temperature (Tre), and skin temperature (Tsk) were continuously measured. The total amount of wakefulness was significantly increased in H compared to C H or C. Compared to C, wakefulness in C H and H was significantly increased during later sleep segments. Tre and mean Tsk were significantly higher in H than in C H or C. In C H, Tsk and Tre increased to levels equal to those observed in H after Ta and RH increase. Whole body sweat loss was significantly lower in C H and C than in H. These results suggest that humid heat exposure in the later sleep segment reduces thermal load as compared to full-night humid heat exposure. In daily life, the use of air conditioning in the initial sleep hours can protect sleep and thermoregulation.

  11. Membrane lateral compressibility determined by NMR and x-ray diffraction: effect of acyl chain polyunsaturation.

    PubMed Central

    Koenig, B W; Strey, H H; Gawrisch, K

    1997-01-01

    The elastic area compressibility modulus, Ka, of lamellar liquid crystalline bilayers was determined by a new experimental approach using 2H-NMR order parameters of lipid hydrocarbon chains together with lamellar repeat spacings measured by x-ray diffraction. The combination of NMR and x-ray techniques yields accurate determination of lateral area per lipid molecule. Samples of saturated, monounsaturated, and polyunsaturated phospholipids were equilibrated with polyethylene glycol (PEG) 20,000 solutions in water at concentrations from 0 to 55 wt % PEG at 30 degrees C. This procedure is equivalent to applying 0 to 8 dyn/cm lateral pressure to the bilayers. The resulting reductions in area per lipid were measured with a resolution of +/-0.2 A2 and the fractional area decrease was proportional to applied lateral pressure. For 1,2-dimyristoyl(d54)-sn-glycero-3-phosphocholine, 1-stearoyl(d35)-2-oleoyl-sn-glycero-3-phosphocholine (SOPC-d35), and 1-stearoyl(d35)-2-docosahexaenoyl-sn-glycero-3-phosphocholine (SDPC-d35) cross-sectional areas per molecule in excess water of 59.5, 61.4, and 69.2 A2 and bilayer elastic area compressibility moduli of 141, 221, and 121 dyn/cm were determined, respectively. Combining NMR and x-ray results enables the determination of compressibility differences between saturated and unsaturated hydrocarbon chains. In mixed-chain SOPC-d35 both chains have similar compressibility moduli; however, in mixed-chain polyunsaturated SDPC-d35, the saturated stearic acid chain appears to be far less compressible than the polyunsaturated docosahexaenoic acid chain. Images FIGURE 3 FIGURE 5 PMID:9336191

  12. Effect of annealing treatment on the performance of organic photovoltaic devices using SPFGraphene as electron-accepter material

    NASA Astrophysics Data System (ADS)

    Wang, HaiTeng; He, DaWei; Wang, YongSheng; Liu, ZhiYong; Wu, HongPeng; Wang, JiGang; Zhao, Yu

    2012-08-01

    We have researched the performances of organic photovoltaic devices with the bulk heterojunction (BHJ) structure using the organic solution-processable functionalized graphene (SPFGraphene) material as the electron-accepter material and P3OT as the donor material. The structural configuration of the device is ITO/PEDOT:PSS/P3OT:PCBM-SPFGraphene/LiF/Al. Given the P3OT/PCBM (1:1) mixture with 8wt% of SPFGraphene, the open-circuit voltage ( V oc) of the device reaches 0.64 V, a short-circuit current density ( J sc) reaches 5.7 mA/cm2, a fill factor ( FF) reaches 0.42, and the power conversion efficiency ( η) reaches 1.53% at illumination at 100 mW/cm2 AM1.5. We further studied the reason for the device performances improvement. In the P3OT:PCBM-SPFGraphene composite, the SPFGraphene material acts as exciton dissociation sites and provides the transport pathways of the lowest unoccupied molecular orbital (LUMO)-SPFGraphene-Al. Furthermore, adding SPFGraphene to P3OT results in appropriate energetic distance between the highest occupied molecular orbital (HOMO) and LUMO of the donor/acceptor and provides higher exciton dissociation volume mobility of carrier transport. We have researched the effect of annealing treatment for the devices and found that the devices with annealing treatment at 180°C show better performances compared with devices without annealed treatment. The devices with annealed treatment show the best performance, with an enhancement of the power conversion efficiency from 1.53% to 1.75%.

  13. Effect of thermal annealing in vacuum on the photovoltaic properties of electrodeposited Cu2O-absorber solar cell

    NASA Astrophysics Data System (ADS)

    Dimopoulos, T.; Peić, A.; Abermann, S.; Postl, M.; List-Kratochvil, E. J. W.; Resel, R.

    2014-07-01

    Heterojunction solar cells were fabricated by electrochemical deposition of p-type, cuprous oxide (Cu2O) absorber on sputtered, n-type ZnO layer. X-ray diffraction measurements revealed that the as-deposited absorber consists mainly of Cu2O, but appreciable amounts of metallic Cu and cupric oxide (CuO) are also present. These undesired oxidation states are incorporated during the deposition process and have a detrimental effect on the photovoltaic properties of the cells. The open circuit voltage (VOC), short circuit current density (jSC), fill factor (FF) and power conversion efficiency (η) of the as-deposited cells are 0.37 V, 3.71 mA/cm2, 35.7% and 0.49%, respectively, under AM1.5G illumination. We show that by thermal annealing in vacuum, at temperatures up to 300 °C, compositional purity of the Cu2O absorber could be obtained. A general improvement of the heterojunction and bulk materials quality is observed, reflected upon the smallest influence of the shunt and series resistance on the transport properties of the cells in dark and under illumination. Independent of the annealing temperature, transport is dominated by the space-charge layer generation-recombination current. After annealing at 300 °C the solar cell parameters could be significantly improved to the values of: VOC = 0.505 V, jSC = 4.67 mA/cm2, FF = 47.1% and η = 1.12%.

  14. Amygdala/hippocampal activation during the menstrual cycle: evidence for lateralization of effects across different tasks.

    PubMed

    Lisofsky, Nina; Lindenberger, Ulman; Kühn, Simone

    2015-01-01

    Variations in hormonal levels between the follicular and the luteal phase of the female menstrual cycle are associated with variations in emotional and cognitive aspects of behavior. The functional neural correlates of these cycle-related variations have been explored in previous neuroimaging studies. We summarize the existing findings of functional magnetic resonance imaging (fMRI) studies to identify regions of increased brain activation in the follicular or luteal phases of the cycle that are concordant across studies. Eleven fMRI studies reporting coordinates of higher brain activation in one of the two main cycle phases were included in the analysis. Activation likelihood estimation was used to determine concordance. We found higher left amygdala/hippocampal activation during the luteal phase and higher right amygdala/hippocampal activation during the follicular phase. Additionally, the anterior cingulate cortex and temporal pole showed increased activation during the luteal phase and the superior temporal gyrus during the follicular phase. The observed pattern of cycle-dependent functional lateralization of the amygdala/hippocampal complex is consistent with findings on cycle-related behavioral variations and on sex differences in lateralization of activity in amygdala and hippocampus. PMID:25496966

  15. Effects of arthroscopic meniscectomy on the long-term prognosis for the discoid lateral meniscus.

    PubMed

    Kim, Sung-Jae; Chun, Yong-Min; Jeong, Jae-Hoon; Ryu, Sang-Wook; Oh, Kyung-Soo; Lubis, Andri M T

    2007-11-01

    This study compared the long-term clinical and radiological outcomes, according to the extent of arthroscopic meniscectomy, of complete and incomplete types of the discoid lateral meniscus. A total of 125 discoid menisci (74 complete and 51 incomplete types) without significant cartilage erosion at the time of surgery were included. The extent of meniscectomy was decided along with tear patterns and the stability of the discoid meniscus. Both clinical and radiological results were evaluated after total or partial meniscectomy. In the complete type of discoid meniscus with less than 5 years of follow-up, the total meniscectomy group showed better clinical results than the partial meniscectomy group. However, with over 5 years of follow-up, there were no differences between the two groups. In the radiological results, there was no significant difference between the two groups during the first 5 years after operation. However, with more than 5 years of follow-up, the partial meniscectomy group showed better results than the total meniscectomy group. In the incomplete-type discoid meniscus, clinical results were better in the partial meniscectomy group regardless of the follow-up periods. In the radiological results, the partial meniscectomy group showed better results for only more than 5 years of follow-up. The long-term prognosis after arthroscopic meniscectomy for the torn discoid lateral meniscus was related to the volume of the meniscus removed. PMID:17762931

  16. Effects of Lateral Mass Screw Rod Fixation to the Stability of Cervical Spine after Laminectomy

    NASA Astrophysics Data System (ADS)

    Rosli, Ruwaida; Kashani, Jamal; Kadir, Mohammed Rafiq Abdul

    There are many cases of injury in the cervical spine due to degenerative disorder, trauma or instability. This condition may produce pressure on the spinal cord or on the nerve coming from the spine. The aim of this study was, to analyze the stabilization of the cervical spine after undergoing laminectomy via computational simulation. For that purpose, a three-dimensional finite element (FE) model for the multilevel cervical spine segment (C1-C7) was developed using computed tomography (CT) data. There are various decompression techniques that can be applied to overcome the injury. Usually, decompression procedures will create an unstable spine. Therefore, in these situations, the spine is often surgically restabilized by using fusion and instrumentation. In this study, a lateral mass screw-rod fixation was created to stabilize the cervical spine after laminectomy. Material properties of the titanium alloy were assigned on the implants. The requirements moments and boundary conditions were applied on simulated implanted bone. Result showed that the bone without implant has a higher flexion and extension angle in comparison to the bone with implant under applied 1Nm moment. The bone without implant has maximum stress distribution at the vertebrae and ligaments. However, the bone with implant has maximum stress distribution at the screws and rods. Overall, the lateral mass screw-rod fixation provides stability to the cervical spine after undergoing laminectomy.

  17. Vacuum ultraviolet radiation and thermal cycling effects on atomic oxygen protective photovoltaic array blanket materials

    NASA Technical Reports Server (NTRS)

    Brady, J.; Banks, B.

    1990-01-01

    The importance of synergistic environmental exposure is demonstrated through the evaluation of DuPont 93-1 in simulated LEO environment. Changes in optical properties, surface condition, and mass loss data are described. The qualitative results indicate the necessity for exposure of materials to a series of simulated LEO environments in order to properly determine synergistic effects and demonstrate the overall LEO durability of candidate materials. It is shown that synergistic effects may occur with vacuum thermal cycling combined with VUV radiation followed by atomic oxygen exposure. Testing the durability of candidate solar array blanket materials in a test sequence with necessary synergistic effects makes it possible to determine the appropriate material for providing structural support and maintaining the proper operating temperature for solar cells in the SSF Photovaltaic Power System.

  18. A new physical insight of RESURF effects based on gradual charge appointment concept for bulk silicon lateral power devices

    NASA Astrophysics Data System (ADS)

    Zhang, Jun; Guo, Yu-Feng; Sun, Yabin; Yang, Kemeng; Lin, Hong; Xia, Xiaojuan; Zhang, Changchun

    2016-04-01

    A novel gradual charge appointment concept is proposed to provide a clear physical insight of RESURF effects in bulk silicon lateral power devices. Due to the expandable substrate depletion region in silicon power device, the Linearly Graded Approximation is unable to fully describe the 2-D coupling effects between vertical and lateral junction. In this paper, by defining a charge appointment line, the lateral abrupt junction behaves as an effective gradual junction, thus resulting in the wider depletion layer, lower field peak and higher breakdown voltage. Based on the hypothesis, a simple 1-D model is proposed to quantify the breakdown voltage of the bulk silicon RESURF device and formulize the surface electric field. To our knowledge, the proposed model is the first 1-D model for bulk silicon RESURF device which can accurately describe the surface field profiles under various applied voltages and structure parameters. Furthermore, we provide a new RESURF criterion to explore the sensitivity of the breakdown voltage to structure parameters. Fair agreements among the analytical, numerical and experimental results verify the availability of the proposed concept and model.

  19. Stimulatory effect of cytokinins and interaction with IAA on the release of lateral buds of pea plants from apical dominance.

    PubMed

    Li, Chunjian; Bangerth, Fritz

    2003-09-01

    Lateral buds of pea plants can be released from apical dominance and even be transformed into dominant shoots when repeatedly treated with synthetic exogenous cytokinins (CKs). The mechanism of the effect of CKs, however, is not clear. The results in this work showed that the stimulatory effects of CKs on the growth of lateral buds and the increase in their fresh weights in pea plants depended on the structure and concentration of the CKs used. The effect of N-(2-chloro-4-pyridyl)-N'-phenylurea (CPPU) was stronger than that of 6-benzylaminopurine (6-BA). Indoleacetic acid (IAA) concentration in shoot, IAA export out of the treated apex and basipetal transport in stems were markedly increased after the application of CPPU or 6-BA to the apex or the second node of pea plant. This increase was positively correlated with the increased concentration of the applied CKs. These results suggest that the increased IAA synthesis and export induced by CKs application might be responsible for the growth of lateral shoots in intact pea plants. PMID:14593807

  20. Space Photovoltaic Research and Technology Conference

    SciTech Connect

    Not Available

    1991-08-01

    The Eleventh Space Photovoltaic Research and Technology conference was held at NASA Lewis Research Center from May 7 to 9, 1991. The papers and workshop summaries presented here report remarkable progress on a wide variety of approaches in space photovoltaics, both near and far term applications. Papers were presented in a variety of technical areas, including multijunction cell technology, GaAs and InP cells, system studies, cell and array development, and photovoltaics for conversion of laser radiation. Three workshops were held to discuss thin film cell development, III-V cell development, and space environmental effects.

  1. Space Photovoltaic Research and Technology Conference

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The Eleventh Space Photovoltaic Research and Technology conference was held at NASA Lewis Research Center from May 7 to 9, 1991. The papers and workshop summaries presented here report remarkable progress on a wide variety of approaches in space photovoltaics, both near and far term applications. Papers were presented in a variety of technical areas, including multijunction cell technology, GaAs and InP cells, system studies, cell and array development, and photovoltaics for conversion of laser radiation. Three workshops were held to discuss thin film cell development, III-V cell development, and space environmental effects.

  2. Residential photovoltaic system designs

    SciTech Connect

    Russell, M. C.

    1981-01-01

    A project to develop Residential Photovoltaic Systems has begun at Massachusetts Institute of Technology Lincoln Laboratory with the construction and testing of five Prototype Systems. All of these systems utilize a roof-mounted photovoltaic array and allow excess solar-generated electric energy to be fed back to the local utility grid, eliminating the need for on-site storage. Residential photovoltaic system design issues are discussed and specific features of the five Prototype Systems now under test are presented.

  3. Photovoltaics - The endless spring

    NASA Technical Reports Server (NTRS)

    Brandhorst, H. W., Jr.

    1984-01-01

    An overview of the developments in the photovoltaic field over the past decade or two is presened. Accomplishments in the terrestrial field are reviewed along with projections and challenges toward meeting cost goals. The contrasts and commonality of space and terrestrial photovoltaics are presented. Finally, a strategic philosophy of photovoltaics research highlighting critical factors, appropriate directions, emerging opportunities, and challenges of the future is given.

  4. Photovoltaics: The endless spring

    NASA Technical Reports Server (NTRS)

    Brandhorst, H. W., Jr.

    1984-01-01

    An overview of the developments in the photovoltaic field over the past decade or two is presented. Accomplishments in the terrestrial field are reviewed along with projections and challenges toward meeting cost goals. The contrasts and commonality of space and terrestrial photovoltaics are presented. Finally, a strategic philosophy of photovoltaics research highlighting critical factors, appropriate directions, emerging opportunities, and challenges of the future is given.

  5. Photovoltaic technology assessment

    SciTech Connect

    Backus, C.E.

    1981-01-01

    After a brief review of the history of photovoltaic devices and a discussion of the cost goals set for photovoltaic modules, the status of photovoltaic technology is assessed. Included are discussions of: current applications, present industrial production, low-cost silicon production techniques, energy payback periods for solar cells, advanced materials research and development, concentrator systems, balance-of-system components. Also discussed are some nontechnical aspects, including foreign markets, US government program approach, and industry attitudes and approaches. (LEW)

  6. Thin film photovoltaics

    SciTech Connect

    Zweibel, K; Ullal, H S

    1989-05-01

    Thin films are considered a potentially attractive technological approach to making cost-effective electricity by photovoltaics. Over the last twenty years, many have been investigated and some (cadmium telluride, copper indium diselenide, amorphous silicon) have become leading candidates for future large-scale commercialization. This paper surveys the past development of these key thin films and gives their status and future prospects. In all cases, significant progress toward cost-effective PV electricity has been made. If this progress continues, it appears that thin film PV could provide electricity that is competitive for summer daytime peaking power requirements by the middle of the 1990s; and electricity in a range that is competitive with fossil fuel costs (i.e., 6 cents/kilowatt-hour) should be available from PV around the turn of the century. 22 refs., 9 figs.

  7. Effect of diffusion from a lateral surface on the rate of GaN nanowire growth

    SciTech Connect

    Sibirev, N. V. Tchernycheva, M.; Cirlin, G. E.; Patriarche, G.; Harmand, J. C.; Dubrovskii, V. G.

    2012-06-15

    The kinetics of the growth of GaN crystalline nanowires on a Si (111) surface with no catalyst is studied experimentally and theoretically. Noncatalytic GaN nanowires were grown by molecular-beam epitaxy with AlN inserts, which makes it possible to determine the rate of the vertical growth of nanowires. A model for the formation of GaN nanowires is developed, and an expression for their rate of growth is derived. It is shown that, in the general case, the dependence of the rate of growth on the nanowire diameter has a minimum. The diameter corresponding to the experimentally observed minimum of the rate of growth steadily increases with increasing diffusion flux from the lateral surface.

  8. The effect of blockage on power production for laterally aligned wind turbines

    NASA Astrophysics Data System (ADS)

    Meyer Forsting, A. R.; Troldborg, N.

    2015-06-01

    This paper studies the change in the individual power coefficients for a laterally aligned row of wind turbines over a single, free turbine in the context of varying inflow directions via numerical simulations. All turbines were rotating in-line with the main flow direction. The problem definition is similar to that of many wind turbine testing sites and wind farms. Hence any changes in the individual turbine power production could have implications regarding power curve validation procedures.These changes are relatively small and therefore the size of the computational domain was identified to be detrimental in avoiding any domain-inflicted blockage. Increasing the misalignment of the main flow direction with the row of turbines led to significant variations in the power production across turbines. At the largest inflow angle of 45° it varied from -1.1% to 2%. As a whole, the power production increased by about 0.5%, almost independent of the inflow direction.

  9. Effect of Geometric Parameters on the Performance of P-Type Junctionless Lateral Gate Transistors

    PubMed Central

    Larki, Farhad; Dehzangi, Arash; Md Ali, Sawal Hamid; Jalar, Azman; Islam, Md. Shabiul; Hamidon, Mohd Nizar; Majlis, Burhanuddin Yeop

    2014-01-01

    This paper examines the impact of two important geometrical parameters, namely the thickness and source/drain extensions on the performance of low doped p-type double lateral gate junctionless transistors (DGJLTs). The three dimensional Technology Computer-Aided Design simulation is implemented to calculate the characteristics of the devices with different thickness and source/drain extension and based on that, the parameters such as threshold voltage, transconductance and resistance in saturation region are analyzed. In addition, simulation results provide a physical explanation for the variation of device characteristics given by the variation of geometric parameters, mainly based on investigation of the electric field components and the carries density variation. It is shown that, the variation of the carrier density is the main factor which affects the characteristics of the device when the device's thickness is varied. However, the electric field is mainly responsible for variation of the characteristics when the source/drain extension is changed. PMID:24743692

  10. Predicting the Effects of Short-Term Photovoltaic Variability on Power System Frequency for Systems with Integrated Energy Storage

    NASA Astrophysics Data System (ADS)

    Traube, Joshua White

    The percentage of electricity supplied by photovoltaic (PV) generators is steadily rising in power systems worldwide. This rise in PV penetration may lead to larger fluctuations in power system frequency due to variability in PV generator output at time scales that fall between the inertial damping and automatic generation control (AGC) responses of power systems. To reduce PV generator variability, active power controls can be implemented in the power electronic inverters that interface PV generators to the power system. Although various types of active power controls have been developed, no standard methodology exists for evaluating the effectiveness of these controls at improving power system frequency regulation. This dissertation presents a method for predicting the effects of short-term PV variability on power system frequency for a PV generator with active power control provided by integrated energy storage. A custom model of a PV generator with integrated energy storage is implemented in a power system dynamic simulator and validated through experiments with a grid emulator. The model is used to predict the effects of short-term PV variability on the frequency of the IEEE 9-bus test power system modified to include a PV generator with integrated energy storage. In addition, this dissertation utilizes linear analysis of power system frequency control to predict worst-case frequency deviations as a function of the amount of energy storage integrated into PV generators. Through simulation and emulation on a scaled experimental prototype, the maximum frequency deviation caused by the PV generator with a small amount of integrated energy storage is found to be approximately 33% lower than the maximum frequency deviation caused by the PV generator alone. Through linear analysis it is shown that by adding only 36.7 kWh of integrated energy storage to a 1.2 MW PV system, the worst-case frequency deviation on the IEEE 9-bus test system can be reduced 65% from 0

  11. The effects of laterally varying icy shell structure on the tidal response of Europa and Ganymede

    NASA Astrophysics Data System (ADS)

    Wahr, J. M.; A, G.; Zhong, S.

    2013-12-01

    One of the long-sought objectives of an icy moon orbiter or fly-by mission, has been to use tidal observations to help determine the existence of a liquid ocean and characteristics of the overlying icy shell. The radio science component of such a mission could be used to estimate the tidal potential Love number k2 for gravity. And if there is an on-board laser altimeter, it could be used to determine the radial displacement Love number h2. Knowledge of either of those Love numbers could provide information on the presence of an ocean beneath the icy outer shell, and the two Love numbers could be combined to place constraints on the thickness of the icy shell. Though if a subsurface ocean exists, complications could conceivably arise if the icy outer shell has significant lateral variations in elastic thickness or shear modulus, or if the ocean is not global in extent so that the icy shell is grounded in places but floating in others. In these cases, the tidal deformation pattern would not be represented as the sum of degree 2 harmonics, and so the results could not be characterized in terms of a single Love number. In this study, by solving a set of tidal loading problems with laterally variable icy shell structures (for which the existence of an ocean layer is assumed), we investigate how those structures might complicate the interpretation of the tide measurements, and we discuss how to extract information regarding the interior structure of Ganymede and Europa from measurements of their tidal response.

  12. Tunable exchange bias-like effect in patterned hard-soft two-dimensional lateral composites with perpendicular magnetic anisotropy

    SciTech Connect

    Hierro-Rodriguez, A. Alvarez-Prado, L. M.; Martín, J. I.; Alameda, J. M.; Teixeira, J. M.; Vélez, M.

    2014-09-08

    Patterned hard-soft 2D magnetic lateral composites have been fabricated by e-beam lithography plus dry etching techniques on sputter-deposited NdCo{sub 5} thin films with perpendicular magnetic anisotropy. Their magnetic behavior is strongly thickness dependent due to the interplay between out-of-plane anisotropy and magnetostatic energy. Thus, the spatial modulation of thicknesses leads to an exchange coupled system with hard/soft magnetic regions in which rotatable anisotropy of the thicker elements provides an extra tool to design the global magnetic behavior of the patterned lateral composite. Kerr microscopy studies (domain imaging and magneto-optical Kerr effect magnetometry) reveal that the resulting hysteresis loops exhibit a tunable exchange bias-like shift that can be switched on/off by the applied magnetic field.

  13. Effect of a short-term psychological intervention on the anxiety and depression of amyotrophic lateral sclerosis patients.

    PubMed

    Díaz, José Luis; Sancho, Jesús; Barreto, Pilar; Bañuls, Pilar; Renovell, Mercedes; Servera, Emilio

    2016-07-01

    This study evaluated the effectiveness of a psychological intervention in amyotrophic lateral sclerosis patients, consisting of four semi-structured sessions of cognitive behavioural therapy combined with counselling techniques. An intervention group and a control group were established. The Hospital Anxiety and Depression Scale was used to assess levels of anxiety and depression. In total, fifty-four patients took part. Prior to the intervention, the intervention group displayed rates of 63.3 and 36.7 per cent for anxiety and depression, respectively, falling to 16.7 and 10.0 per cent afterwards. The psychological intervention demonstrated potential for the reduction of levels of anxiety and depression in amyotrophic lateral sclerosis patients. PMID:25370571

  14. Tunable exchange bias-like effect in patterned hard-soft two-dimensional lateral composites with perpendicular magnetic anisotropy

    NASA Astrophysics Data System (ADS)

    Hierro-Rodriguez, A.; Teixeira, J. M.; Vélez, M.; Alvarez-Prado, L. M.; Martín, J. I.; Alameda, J. M.

    2014-09-01

    Patterned hard-soft 2D magnetic lateral composites have been fabricated by e-beam lithography plus dry etching techniques on sputter-deposited NdCo5 thin films with perpendicular magnetic anisotropy. Their magnetic behavior is strongly thickness dependent due to the interplay between out-of-plane anisotropy and magnetostatic energy. Thus, the spatial modulation of thicknesses leads to an exchange coupled system with hard/soft magnetic regions in which rotatable anisotropy of the thicker elements provides an extra tool to design the global magnetic behavior of the patterned lateral composite. Kerr microscopy studies (domain imaging and magneto-optical Kerr effect magnetometry) reveal that the resulting hysteresis loops exhibit a tunable exchange bias-like shift that can be switched on/off by the applied magnetic field.

  15. Biological Applications of Extraordinary Electroconductance and Photovoltaic Effects in Inverse Extraordinary Optoconductance

    NASA Astrophysics Data System (ADS)

    Tran, Lauren Christine

    The Extraordinary Electroconductance (EEC) sensor has been previously demonstrated to have an electric field sensitivity of 3.05V/cm in a mesoscopic-scale structure fabricated at the center of a parallel plate capacitor. In this thesis, we demonstrate the first successful application of EEC sensors as electrochemical detectors of protein binding and biological molecule concentration. Using the avidin derivative, captavidin, in complex with the vitamin biotin, the change in four-point measured resistance with fluid protein concentration of bare EEC sensors was shown to increase by a factor of four in the presence of biomolecular binding as compared to baseline. Calculations for approximate field strengths introduced by a bound captavidin molecule are also presented. The development of Inverse-Extraordinary Optoconductance (I-EOC), an effect which occurs in nanoscale sensors, is also discussed. In the I-EOC effect, electron transport transitions from ballistic to diffusive with increasing light intensity. In these novel, room temperature optical detectors, the resistance is low at low light intensity and resistance increases by 9462% in a 250nm device mesa upon full illumination with a 5 mW HeNe laser. This is the inverse of bulk and mesoscopic device behavior, in which resistance decreases with increasing photon density.

  16. Left-lateralized N170 effects of visual expertise in reading: evidence from Japanese syllabic and logographic scripts.

    PubMed

    Maurer, Urs; Zevin, Jason D; McCandliss, Bruce D

    2008-10-01

    The N170 component of the event-related potential (ERP) reflects experience-dependent neural changes in several forms of visual expertise, including expertise for visual words. Readers skilled in writing systems that link characters to phonemes (i.e., alphabetic writing) typically produce a left-lateralized N170 to visual word forms. This study examined the N170 in three Japanese scripts that link characters to larger phonological units. Participants were monolingual English speakers (EL1) and native Japanese speakers (JL1) who were also proficient in English. ERPs were collected using a 129-channel array, as participants performed a series of experiments viewing words or novel control stimuli in a repetition detection task. The N170 was strongly left-lateralized for all three Japanese scripts (including logographic Kanji characters) in JL1 participants, but bilateral in EL1 participants viewing these same stimuli. This demonstrates that left-lateralization of the N170 is dependent on specific reading expertise and is not limited to alphabetic scripts. Additional contrasts within the moraic Katakana script revealed equivalent N170 responses in JL1 speakers for familiar Katakana words and for Kanji words transcribed into novel Katakana words, suggesting that the N170 expertise effect is driven by script familiarity rather than familiarity with particular visual word forms. Finally, for English words and novel symbol string stimuli, both EL1 and JL1 subjects produced equivalent responses for the novel symbols, and more left-lateralized N170 responses for the English words, indicating that such effects are not limited to the first language. Taken together, these cross-linguistic results suggest that similar neural processes underlie visual expertise for print in very different writing systems. PMID:18370600

  17. Effect of the quantum well thickness on the performance of InGaN photovoltaic cells

    SciTech Connect

    Redaelli, L.; Mukhtarova, A.; Valdueza-Felip, S.; Ajay, A.; Durand, C.; Eymery, J.; Monroy, E.; Faure-Vincent, J.

    2014-09-29

    We report on the influence of the quantum well thickness on the effective band gap and conversion efficiency of In{sub 0.12}Ga{sub 0.88}N/GaN multiple quantum well solar cells. The band-to-band transition can be redshifted from 395 to 474 nm by increasing the well thickness from 1.3 to 5.4 nm, as demonstrated by cathodoluminescence measurements. However, the redshift of the absorption edge is much less pronounced in absorption: in thicker wells, transitions to higher energy levels dominate. Besides, partial strain relaxation in thicker wells leads to the formation of defects, hence degrading the overall solar cell performance.

  18. The Solar Spectrum on the Martian Surface and its Effect on Photovoltaic Performance

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.; Hyatt, Daniel

    2007-01-01

    Solar cells operating on the surface of Mars receive a spectrum of illumination different from the AM0 spectrum, since the sunlight is filtered by dust suspended in the atmosphere. This spectrum changes with the amount of dust in the atmosphere, as well as with air mass change due to time of day and season. This spectral variation affects the performance of solar cells. We used data from Mars Exploration Rovers to measure this spectrum. By comparing the measured intensity with the known reflectance of the pancam calibration target on the rovers Spirit and Opportunity, we measure the solar spectrum reaching the surface. The effect of this spectrum on the performance of solar cells is then calculated based on the spectral response of several different solar cell types.

  19. The Solar Spectrum on the Martian Surface and Its Effect on Photovoltaic Performance

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.; Hyatt, Dan

    2006-01-01

    Solar cells operating on the surface of Mars receive a spectrum of illumination different from the AM0 spectrum, since the sunlight is filtered by dust suspended in the atmosphere. This spectrum changes with the amount of dust in the atmosphere, as well as with air mass change due to time of day and season. This spectral variation affects the performance of solar cells. We used data from Mars Exploration Rovers to measure this spectrum. By comparing the measured intensity with the known reflectance of the pancam calibration target on the rovers Spirit and Opportunity, we measure the solar spectrum reaching the surface. The effect of this spectrum on the performance of solar cells is then calculated based on the spectral response of several different solar cell types.

  20. Effects of Bulky Substituents of Push-Pull Porphyrins on Photovoltaic Properties of Dye-Sensitized Solar Cells.

    PubMed

    Higashino, Tomohiro; Kawamoto, Kyosuke; Sugiura, Kenichi; Fujimori, Yamato; Tsuji, Yukihiro; Kurotobi, Kei; Ito, Seigo; Imahori, Hiroshi

    2016-06-22

    To evaluate the effects of substituent bulkiness around a porphyrin core on the photovoltaic properties of porphyrin-sensitized solar cells, long alkoxy groups were introduced at the meso-phenyl group (ZnPBAT-o-C8) and the anchoring group (ZnPBAT-o-C8Cn, n = 4, 8) of an asymmetrically substituted push-pull porphyrin with double electron-donating diarylamino groups and a single electron-withdrawing carboxyphenylethynyl anchoring group. The spectroscopic and electrochemical properties of ZnPBAT-o-C8 and ZnPBAT-o-C8Cn were found to be superior to those of a push-pull porphyrin reference (YD2-o-C8), demonstrating their excellent light-harvesting and redox properties for dye-sensitized solar cells. A power conversion efficiency (η) of the ZnPBAT-o-C8-sensitized solar cell (η = 9.1%) is higher than that of the YD2-o-C8-sensitized solar cell (η = 8.6%) using iodine-based electrolyte due to the enhanced light-harvesting ability of ZnPBAT-o-C8. In contrast, the solar cells based on ZnPBAT-o-C8Cn, possessing the additional alkoxy chains in the anchoring group, revealed the lower η values of 7.3% (n = 4) and 7.0% (n = 8). Although ZnPBAT-o-C8Cn exhibited higher resistance at the TiO2-dye-electrolyte interface by virtue of the extra alkoxy chains, the reduced amount of the porphyrins on TiO2 by excessive addition of coadsorbent chenodeoxycholic acid (CDCA) for mitigating the aggregation on TiO2 resulted in the low η values. Meanwhile, the ZnPBAT-o-C8-sensitized solar cell showed the lower η value of 8.1% than the YD2-o-C8-sensitized solar cell (η = 9.8%) using cobalt-based electrolyte. The smaller η value of the ZnPBAT-o-C8-sensitized solar cell may be attributed to the insufficient blocking effect of the bulky substituents of ZnPBAT-o-C8 under the cobalt-based electrolyte conditions. Overall, the alkoxy chain length and substitution position around the porphyrin core are important factors to affect the cell performance. PMID:27267428

  1. Fabrication of Semi-Transparent Photovoltaic Cell by a Cost-Effective Technique

    NASA Astrophysics Data System (ADS)

    Nithyayini, K. N.; Ramasesha, Sheela K.

    2015-09-01

    Semi-transparent inorganic thin film PV cells have been fabricated using n-type (CdS) and p-type (CdTe) semiconductors. Large area devices which can be used as windows and skylights in buildings can be fabricated using cost effective solution processes. The device structure is Glass/TCO/CdTe/CdS/TCO. Chemically stable CdS and CdTe layers are deposited at temperatures 353 K to 373 K (80 °C to 100 °C) under controlled pH. The CdCl2 activation is carried out followed by air annealing. The p-n junction is formed by sintering the device at 673 K to 723 K (400 °C to 450 °C). The characterization of cells is carried out using XRD, SEM, AFM, and UV-Visible spectroscopy. The thickness of the cell is ~600 nm. The band gap values are 2.40 eV for CdS and 1.36 eV for CdTe with transmittance of about 70 pct in the visible region. Under 1.5 AM solar spectrum, V oc, and I sc of the initial device are 3.56e-01 V and 6.20e-04 A, respectively.

  2. Benzimidazole-Branched Isomeric Dyes: Effect of Molecular Constitution on Photophysical, Electrochemical, and Photovoltaic Properties.

    PubMed

    Bodedla, Govardhana Babu; Justin Thomas, K R; Fan, Miao-Syuan; Ho, Kuo-Chuan

    2016-01-15

    Three benzimidazole-based isomeric organic dyes possessing two triphenylamine donors and a cyanoacrylic acid acceptor are prepared by stoichiometrically controlled Stille or Suzuki-Miyaura coupling reaction which predominantly occurs on the N-butyl side of benzimidazole due to electronic preferences. Combined with the steric effect of the N-butyl substituent, placement of the acceptor segment at various nuclear positions of benzimidazole such as C2, C4, and C7 led to remarkable variations in intramolecular charge transfer absorption, electron injection efficiency, and charge recombination kinetics. The substitution of acceptor on the C4 led to red-shifted absorption, while that on C7 retarded the charge transfer due to twisting in the structure caused by the butyl group. Because of the cross-conjugation nature and poor electronic interaction between the donor and acceptor, the dye containing triphenylamine units on C4 and C7 and the acceptor unit on C2 showed the low oxidation potential. Thus, this dye possesses favorable HOMO and LUMO energy levels to render efficient sensitizing action in solar cells. Consequently, it results in high power conversion efficiency (5.01%) in the series with high photocurrent density and open circuit voltage. The high photocurrent generation by this dye is reasoned to it exceptional charge collection efficiency as determined from the electron impedance spectroscopy. PMID:26679036

  3. Reliability Research for Photovoltaic Modules

    NASA Technical Reports Server (NTRS)

    Ross, Ronald J., Jr.

    1986-01-01

    Report describes research approach used to improve reliability of photovoltaic modules. Aimed at raising useful module lifetime to 20 to 30 years. Development of cost-effective solutions to module-lifetime problem requires compromises between degradation rates, failure rates, and lifetimes, on one hand, and costs of initial manufacture, maintenance, and lost energy, on other hand. Life-cycle costing integrates disparate economic terms, allowing cost effectiveness to be quantified, allowing comparison of different design alternatives.

  4. Thickness Effect on Properties of Sprayed In2S3 Films for Photovoltaic Applications

    NASA Astrophysics Data System (ADS)

    Bouguila, N.; Kraini, M.; Halidou, I.; Lacaze, E.; Bouchriha, H.; Bouzouita, H.

    2016-01-01

    Indium sulfide (In2S3) films have been deposited on soda-lime glass substrates using a spray technique (CSP). Indium chloride and thiourea were used as precursors at a molar ratio of S:In = 2. The substrate temperature was fixed at 340°C. The effect of film thickness on the structural, morphological and optical properties of the as-deposited films has been studied. These films were characterized by x-ray diffraction, scanning electron microscopy (SEM), atomic force microscopy (AFM) and optical absorption spectroscopy. As-prepared samples were polycrystalline with a cubic structure and (400) as preferential orientation. Their grain size increased from 35 nm to 41 nm with increasing thickness whereas the dislocation density and microstrain of the films decreased with the increase of thickness. Both SEM and AFM images showed that the films were homogenous with an increase of the surface roughness with the increase of thickness. The optical transmittance of the films decreased from 80% to 20% in the visible and infrared regions when the thickness was increased from 0.78 μm to 6.09 μm. The optical band gap E g was found to be in the range of 2.75-2.19 eV and showed a decrease with film thickness. Based on the measured optical constants (n and k), a Wemple-Didomenico model was used to determine the values of single oscillator energy ( E 0), dispersion energy ( E d), optical band gap ( E g) and high frequency dielectric constant ( \\varepsilon_{∞} ). In addition, these films exhibited n-type conductivity and were highly resistive. These results confirm that In2S3 thin films are a promising alternative as a buffer-layer material for CuInGa(S,Se)2-based solar cells.

  5. Effect of lateral contraction and magnetism on the energy release upon fracture in metals: First-principles computational tensile tests

    NASA Astrophysics Data System (ADS)

    Tian, Z. X.; Yan, J. X.; Xiao, W.; Geng, W. T.

    2009-04-01

    On many occasions, there is an energy release upon fracture of materials. Taking the Σ5 (210) grain boundary in nickel as an example, we have studied the effect of lateral contraction (the Poisson effect) upon stretching and the effect of magnetism on the energy release at the break point, using density-functional theory computational tensile tests. For both clean and sulfur segregated grain boundaries, our calculations show that the Poisson effect can reduce the total energy of the grain-boundary system remarkably. For Σ3 (111) grain boundary, however, lateral optimization of the computation cell has only a minor effect because of the close packing of the Ni (111) plane. Surprisingly, magnetism is found to reduce much of the energy release upon fracture for grain boundaries for such a weak magnetic metal. As a result, the calculated ultimate tensile strength of the material will be significantly diminished. Segregated sulfur atoms reduce the energy barrier between metastable and ground-state configurations in straining procedure. Near the break point, spin polarization of the interfacial atoms is significantly enhanced which introduces an extra energy lowering of the system.

  6. Analysis of shadowing effects on MIR photovoltaic and solar dynamic power systems

    NASA Technical Reports Server (NTRS)

    Fincannon, James

    1995-01-01

    The NASA Lewis Research Center is currently working with RSC-Energia, the Russian Space Agency, and Allied Signal in developing a flight demonstration solar dynamic power system. This type of power system is dependent upon solar flux that is reflected and concentrated into a thermal storage system to provide the thermal energy input to a closed-cycle Brayton heat engine. The solar dynamic unit will be flown on the Russian Mir space station in anticipation of use on the International Space Station Alpha. By the time the power system is launched, the Mir will be a spatially complex configuration which will have, in addition to the three-gimbaled solar dynamic unit, eleven solar array wings that are either fixed or track the Sun along one axis and a variety or repositionable habitation and experiment modules. The proximity of arrays to modules creates a situation which makes it highly probable that there will be varying solar flux due to shadowing on the solar dynamic unit and some of the arrays throughout the orbit. Shadowing causes fluctuations in the power output from the arrays and the solar dynamic power system, thus reducing the energy capabilities of the spacecraft. An assessment of the capabilities of the power system under these conditions is an important part in influencing the design and operations of the spacecraft and predicting its energy performance. This paper describes the results obtained from using the Orbiting Spacecraft Shadowing Analysis Station program that was integrated into the Station Power Analysis for Capability Evaluation (SPACE) electrical power system computer program. OSSA allows one to consider the numerous complex factors for analyzing the shadowing effects on the electrical power system including the variety of spacecraft hardware geometric configurations, yearly and daily orbital variations in the vehicle attitude and orbital maneuvers (for communications coverage, payload pointing requirements and rendezvous/docking with other

  7. Effect of Lateral Size of Graphene Quantum Dots on Their Properties and Application.

    PubMed

    Zhang, Fangwei; Liu, Fei; Wang, Chong; Xin, Xiaozhen; Liu, Jingyuan; Guo, Shouwu; Zhang, Jingyan

    2016-01-27

    Well-defined graphene quantum dots (GQDs) are crucial for their biological applications and the construction of nanoscaled optoelectronic and electronic devices. However, as-synthesized GQDs reported in many works assume a very wide lateral size distribution; thus, their apparent properties cannot truthfully reflect intrinsic properties of the well-defined GQDs, and more importantly, the applications of GQDs will be affected and limited as well. In this work, we demonstrated that different sized GQDs with a narrow size distribution could be obtained via gel electrophoresis of the crude GQDs prepared through a photo-Fenton reaction of graphene oxide (GO). It is illustrated that the photoluminesce (PL) emissions of the well-defined GQDs originated mainly from the peripheral carboxylic groups and conjugated carbon backbone planes through fluorescence and UV-vis spectroscopies. More importantly, our findings challenge the notion that the excitation wavelength dependent PL property of the as-synthesized GQDs is the intrinsic property of the size-defined GQDs. Preliminary data at the cellular level indicated that the small sized GQDs exhibit weaker quenching DNA dye ability but higher toxicity to the cells compared to that of the as-synthesized GQDs. This discovery is essential to explore applications of the GQDs in pharmaceutics and to understand the origin of the optoelectronic properties of GQDs. PMID:26725374

  8. Effect of Different Coarse Aggregate Sizes on the Strength Characteristics of Laterized Concrete

    NASA Astrophysics Data System (ADS)

    Salau, M. A.; Busari, A. O.

    2015-11-01

    The high cost of conventional concrete materials is a major factor affecting housing delivery in developing countries such as Nigeria. Since Nigeria is blessed with abundant locally available materials like laterite, researchers have conducted comprehensive studies on the use of laterite to replace river sand partially or fully in the concrete. However, the works did not consider the optimum use of coarse aggregate to possibly improve the strength of the laterized concrete, since it is normally lower than that of normal concrete. The results of the tests showed that workability, density and compressive strength at constant water-cement ratio increase with the increase in the coarse aggregate particle size and also with curing age. As the percentage of laterite increases, there was a reduction in all these characteristics even with the particle size of coarse aggregate reduction due to loss from the aggregate-paste interface zone. Also, when sand was replaced by 25% of laterite, the 19.5mm and 12.5mm coarse aggregate particle sizes gave satisfactory results in terms of workability and compressive strength respectively at 28 days of curing age, compared to normal concrete. However, in case of 50% up to 100% laterite contents, the workability and compressive strength values were very low.

  9. On the Effects of the Lateral Strains on the Fiber Bragg Grating Response

    PubMed Central

    Lai, Marco; Karalekas, Dimitris; Botsis, John

    2013-01-01

    In this paper, a combined experimental-numerical based work was undertaken to investigate the Bragg wavelength shift response of an embedded FBG sensor when subjected to different conditions of multi-axial loading (deformation). The following cases are examined: (a) when an isotropic host material with no constrains on planes normal to the embedded sensor's axis is biaxially loaded, (b) when the same isotropic host material is subjected to hydrostatic pressure and (c) when the hydrostatically loaded host material is an anisotropic one, as in the case of a composite material, where the optical fiber is embedded along the reinforcing fibers. The comparison of the experimental results and the finite element simulations shows that, when the axial strain on the FBG sensor is the dominant component, the standard wavelength-shift strain relation can be used even if large lateral strains apply on the sensor. However when this is not the case, large errors may be introduced in the conversion of the wavelength to axial strains on the fiber. This situation arises when the FBG is placed parallel to high modulus reinforcing fibers of a polymer composite. PMID:23429580

  10. Assessing the effects of a sequestered germline on interdomain lateral gene transfer in Metazoa.

    PubMed

    Jensen, Lindy; Grant, Jessica R; Laughinghouse, Haywood Dail; Katz, Laura A

    2016-06-01

    A sequestered germline in Metazoa has been argued to be an obstacle to lateral gene transfer (LGT), though few studies have specifically assessed this claim. Here, we test the hypothesis that the origin of a sequestered germline reduced LGT events in Bilateria (i.e., triploblast lineages) as compared to early-diverging Metazoa (i.e., Ctenophora, Cnidaria, Porifera, and Placozoa). We analyze single-gene phylogenies generated with over 900 species sampled from among Bacteria, Archaea, and Eukaryota to identify well-supported interdomain LGTs. We focus on ancient interdomain LGT (i.e., those between prokaryotes and multiple lineages of Metazoa) as systematic errors in single-gene tree reconstruction create uncertainties for interpreting eukaryote-to-eukaryote transfer. The breadth of the sampled Metazoa enables us to estimate the timing of LGTs, and to examine the pattern before versus after the evolution of a sequestered germline. We identified 58 LGTs found only in Metazoa and prokaryotes (i.e., bacteria and/or archaea), and seven genes transferred from prokaryotes into Metazoa plus one other eukaryotic clade. Our analyses indicate that more interdomain transfers occurred before the development of a sequestered germline, consistent with the hypothesis that this feature is an obstacle to LGT. PMID:27139503

  11. Disrupted effective connectivity of the sensorimotor network in amyotrophic lateral sclerosis.

    PubMed

    Fang, Xiaojing; Zhang, Yuanchao; Wang, Yue; Zhang, Yuling; Hu, Jun; Wang, Jian; Zhang, Jiuquan; Jiang, Tianzi

    2016-03-01

    Although dysfunctional sensorimotor network (SMN) has been frequently involved in the pathogenesis of amyotrophic lateral sclerosis (ALS), the causal relationship within this network remains unexplored. In this study, spectral dynamic causal modeling was applied to resting-state functional magnetic resonance imaging data to estimate the causal relationship of SMN in a cohort of 20 ALS patients and 21 healthy controls. The SMN components were first extracted using an independent component analysis, and then compared between the two groups to identify the abnormalities in SMN. In ALS patients, we found significant regional activity alterations in the left primary motor cortex (M1), the left primary somatosensory cortex (S1), and the right supplementary motor cortex (SMA). Among these regions, spectral DCM revealed missing closed-loop circuit between the left M1 and the right SMA, and lost projection from the right SMA to the left S1 in ALS. These findings may reflect the influences of the loss of motor neurons on motor function in ALS, and provide compelling evidence for a breakdown of the sensorimotor neural circuits in ALS. In conclusion, this study elucidates a neurobiological model that may explain the functional impairments of the SMN in ALS, and provides much deeper insights into the pathophysiology of this disease. PMID:26743627

  12. Misperceiving facial affect: effects of laterality and individual differences in susceptibility to visual hallucinations.

    PubMed

    Coy, Abbie L; Hutton, Samuel B

    2012-04-30

    It has been suggested that certain types of auditory hallucinations may be the by-product of a perceptual system that has evolved to be oversensitive to threat-related stimuli. People with schizophrenia and high schizotypes experience visual as well as auditory hallucinations, and have deficits in processing facial emotions. We sought to determine the relationship between visual hallucination proneness and the tendency to misattribute threat and non-threat related emotions to neutral faces. Participants completed a questionnaire assessing visual hallucination proneness (the Revised Visual Hallucination Scale - RVHS). High scoring individuals (N=64) were compared to low scoring individuals (N=72) on a novel emotion detection task. The high RVHS group made more false positive errors (ascribing emotions to neutral faces) than the low RVHS group, particularly when detecting threat-related emotions. All participants made more false positives when neutral faces were presented to the right visual field than to the left visual field. Our results support continuum models of visual hallucinatory experience in which tolerance for false positives is highest for potentially threatening emotional stimuli and suggest that lateral asymmetries in face processing extend to the misperception of facial emotion. PMID:22382049

  13. Series interconnected photovoltaic cells and method for making same

    DOEpatents

    Albright, S.P.; Chamberlin, R.R.; Thompson, R.A.

    1995-01-31

    A novel photovoltaic module and method for constructing the same are disclosed. The module includes a plurality of photovoltaic cells formed on a substrate and laterally separated by interconnection regions. Each cell includes a bottom electrode, a photoactive layer and a top electrode layer. Adjacent cells are connected in electrical series by way of a conductive-buffer line. The buffer line is also useful in protecting the bottom electrode against severing during downstream layer cutting processes. 11 figs.

  14. Two-dimensional plasmons in lateral carbon nanotube network structures and their effect on the terahertz radiation detection

    NASA Astrophysics Data System (ADS)

    Ryzhii, V.; Otsuji, T.; Ryzhii, M.; Leiman, V. G.; Fedorov, G.; Goltzman, G. N.; Gayduchenko, I. A.; Titova, N.; Coquillat, D.; But, D.; Knap, W.; Mitin, V.; Shur, M. S.

    2016-07-01

    We consider the carrier transport and plasmonic phenomena in the lateral carbon nanotube (CNT) networks forming the device channel with asymmetric electrodes. One electrode is the Ohmic contact to the CNT network and the other contact is the Schottky contact. These structures can serve as detectors of the terahertz (THz) radiation. We develop the device model for collective response of the lateral CNT networks which comprise a mixture of randomly oriented semiconductor CNTs (s-CNTs) and quasi-metal CNTs (m-CNTs). The proposed model includes the concept of the collective two-dimensional (2D) plasmons in relatively dense networks of randomly oriented CNTs (CNT "felt") and predicts the detector responsivity spectral characteristics exhibiting sharp resonant peaks at the signal frequencies corresponding to the 2D plasmonic resonances. The detection mechanism is the rectification of the ac current due the nonlinearity of the Schottky contact current-voltage characteristics under the conditions of a strong enhancement of the potential drop at this contact associated with the plasmon excitation. The detector responsivity depends on the fractions of the s- and m-CNTs. The burning of the near-contact regions of the m-CNTs or destruction of these CNTs leads to a marked increase in the responsivity in agreement with our experimental data. The resonant THz detectors with sufficiently dense lateral CNT networks can compete and surpass other THz detectors using plasmonic effects at room temperatures.

  15. The Effects of Kinesiotape Applied to the Lateral Aspect of the Ankle: Relevance to Ankle Sprains – A Systematic Review

    PubMed Central

    Wilson, Brendan; Bialocerkowski, Andrea

    2015-01-01

    Objective To identify, evaluate and synthesise evidence on the effect of kinesiotape applied to the lateral aspect of the ankle, through a systematic review of quantitative studies. Data Sources A search for quantitative studies was undertaken using key terms of “kinesiotape” and “ankle” in seven electronic databases, using the maximum date ranges. Databases included: the Cochrane Library, Cumulative Index to Nursing and Allied Health Literature, Medline, Physiotherapy Evidence Database, Scopus, SPORTDiscus and Web of Science. Study Selection Database hits were evaluated against explicit inclusion criteria. From 107 database hits, 8 quantitative studies were included. Data Extraction Two independent reviewers appraised the methodological rigour of the studies using the McMaster Critical Review Form for Quantitative Studies. Data were extracted on participant characteristics, kinesiotape parameters, comparison interventions, outcome measures and findings. Data Syntheses Most studies (n=7) had good to very good methodological rigour. Meta-analysis was not possible due to heterogeneity in participants, interventions and outcome measures. No adverse events were reported. Kinesiotape may produce different effects in healthy and injured ankles. In healthy ankles, kinesiotape may increase postural control, whereas in injured ankles it may improve proprioception, plantarflexor endurance and the performance of activities. These trends were identified from a small body of evidence including 276 participants. Conclusions It is recommended that kinesiotape may be used in clinical practice to prevent lateral ankle injuries (through its effects on postural control) and manage lateral ankle injuries due to its positive effects on proprioception, muscle endurance and activity performance. It appears that kinesiotape may not provide sufficient mechanical support to improve postural control in unstable ankles. Adverse events associated with kinseiotape are unlikely. PMID

  16. Reliability of photovoltaic modules

    NASA Technical Reports Server (NTRS)

    Ross, R. G., Jr.

    1986-01-01

    In order to assess the reliability of photovoltaic modules, four categories of known array failure and degradation mechanisms are discussed, and target reliability allocations have been developed within each category based on the available technology and the life-cycle-cost requirements of future large-scale terrestrial applications. Cell-level failure mechanisms associated with open-circuiting or short-circuiting of individual solar cells generally arise from cell cracking or the fatigue of cell-to-cell interconnects. Power degradation mechanisms considered include gradual power loss in cells, light-induced effects, and module optical degradation. Module-level failure mechanisms and life-limiting wear-out mechanisms are also explored.

  17. Effect of Distributed Photovoltaic Generation on the Voltage Magnitude in a Self-Contained Power Supply System

    NASA Astrophysics Data System (ADS)

    Lukutin, B. V.; Shandarova, E. B.; Makarova, A. F.; Shvartsman, I. B.

    2016-04-01

    A promising way to increase the technical and economic characteristics of standalone power supply systems is to incorporate renewable energy installations in their structure. This saves fuel and extends the operational life of diesel power stations. The most common option is a hybrid system with photovoltaic power stations incorporated into the local network of the diesel power station. This paper deals with the dependence of the deflection voltage and power losses in the electric power transmission line on the graphs of electrical loads, the parameters of elements of the power supply system, connection points and the capacity of distributed photovoltaic power stations. Research has been carried out on the common low-voltage power supply systems of the radial type (0.4 kV) with an installed capacity of up to 100 kW. The studies have been conducted by simulating the operating modes of hybrid power systems of various configurations. As a result of these studies recommendations to reduce losses and voltage variations in the network by selecting the power and photovoltaic power connection points have been put forward.

  18. Effectiveness of chest compression feedback during cardiopulmonary resuscitation in lateral tilted and semirecumbent positions: a randomised controlled simulation study.

    PubMed

    Song, Y; Oh, J; Chee, Y; Cho, Y; Lee, S; Lim, T H

    2015-11-01

    Feedback devices have been shown to improve the quality of chest compression during cardiopulmonary resuscitation for patients in the supine position, but no studies have reported the effects of feedback devices on chest compression when the chest is tilted. Basic life support-trained providers were randomly assigned to administer chest compressions to a manikin in the supine, 30° left lateral tilt and 30° semirecumbent positions, with or without the aid of a feedback device incorporated into a smartphone. Thirty-six participants were studied. The feedback device did not affect the quality of chest compressions in the supine position, but improved aspects of performance in the tilted positions. In the lateral tilted position, the median (IQR [range]) chest compression rate was 99 (99-100 [96-117]) compressions.min(-1) with and 115 (95-128 [77-164]) compressions.min(-1) without feedback (p = 0.05), and the proportion of compressions of correct depth was 55 (0-96 [0-100])% with and 1 (0-30 [0-100])% without feedback (p = 0.03). In the semirecumbent position, the proportion of compressions of correct depth was 21 (0-87 [0-100])% with and 1 (0-26 [0-100])% without feedback (p = 0.05). Female participants applied chest compressions at a more accurate rate using the feedback device in the lateral tilted position but were unable to increase the chest compression depth, whereas male participants were able to increase the force of chest compression using the feedback device in the lateral tilted and semirecumbent positions. We conclude that a feedback device improves the application of chest compressions during simulated cardiopulmonary resuscitation when the chest is tilted. PMID:26349025

  19. Dietary zinc deficiency effects dorso-lateral and ventral prostate of Wistar rats: histological, biochemical and trace element study.

    PubMed

    Joshi, Sangeeta; Nair, Neena; Bedwal, R S

    2014-10-01

    Zinc deficiency has become a global problem affecting the developed and developing countries due to inhibitors in the diet which prevents its absorption or due to a very low concentration of bioavailable zinc in the diet. Being present in high concentration in the prostate and having diverse biological function, we investigated the effects of dietary zinc deficiency for 2 and 4 weeks on dorso-lateral and ventral prostate. Sixty prepubertal rats were divided into three groups: zinc control (ZC), pair fed (PF) and zinc deficient (ZD) and fed on 100 μg/g (zinc control and pair fed groups) and 1 μg/g (zinc deficient) diet. Zinc deficiency was associated with degenerative changes in dorso-lateral and ventral prostate as made evident by karyolysis, karyorhexis, cytoplasmolysis, loss of cellularisation, decreased intraluminar secretion and degeneration of fibromuscular stroma. In response, protein carbonyl, nitric oxide, acid phosphatase, 3β-hydroxysteroid dehydrogenase and 17β-hydroxysteroid dehydrogenase increased, exhibiting variable level of significance. Total protein and total zinc concentration in dorso-lateral and ventral prostate as well as in serum decreased (P < 0.001). Decrease (P < 0.001) was recorded in serum FSH and testosterone after 2 and 4 weeks of zinc deficiency. The changes were more prominent after 4 weeks of synthetic zinc deficient diet. The results indicate that zinc deficiency during prepubertal period affects the prostate structure, total protein concentration, enhanced protein carbonyl concentration, nitric oxide as well as acid phosphatase activities and impaired hydroxysteroid dehydrogenase activities. Evidently these changes could be attributed to dysfunction of dorso-lateral and ventral prostate after dietary zinc deficiency as well as impairment of metabolic and secretory activity, reduced gonadotropin levels by hypothalamus -hypophysial system which is indicative of a critical role of zinc in maintaining the prostate integrity. PMID

  20. The effect of hydroxyapatite coated screw in the lateral fragility fractures of the femur. A prospective randomized clinical study.

    PubMed

    Pesce, V; Maccagnano, G; Vicenti, G; Notarnicola, A; Moretti, L; Tafuri, S; Vanni, D; Salini, V; Moretti, B

    2014-01-01

    Due to a growing numbers of lateral fragility fractures of the femur and their high social costs the need to work out an effective strategy in order to find a better solution for these patients is warranted. From January 2010 to July 2011, we carried out a prospective randomized clinical study comparing the results of patients with femoral lateral fractures treated by nail and cephalic hydroxyapatite coated screws (study group including 27 patients) compared to the patients with the same fractures treated with nail and head standard screws (control group including 27 patients). We defined the two parts of the femoral neck as ROI 1 (under the head screw) and ROI 2 (above the femoral screw) on the AP view. The bone density of the two areas was calculated using DEXA at T0 (1st day post-surgery), at T1 (40th day post-surgery), at T2 (3 months later), at T3 (1 year later). The clinical-radiography evaluations were based on the Harris Hip Score (HHS), ADL test and x-ray views of the hip. As far as the bone mineral density average of ROI 1 and ROI 2 is concerned, we found a significant statistical increase at T1 and T3 in the study group, while it was not significant in the control group. We could account for this data through the higher mechanical stability of hydroxyapatite coated screws than standard screws. In fact, this material was responsible for improved implant osteointegration. Thanks to a 1 year follow-up we were able to demonstrate the implant utility associated with augmentation and the importance of densitometry exams such as easily repeatable and low cost diagnostics to prevent the onset of complications linked to screw loosening. PMID:24750798

  1. Solar Photovoltaic Energy.

    ERIC Educational Resources Information Center

    Ehrenreich, Henry; Martin, John H.

    1979-01-01

    The goals of solar photovoltaic technology in contributing to America's future energy needs are presented in this study conducted by the American Physical Society. Although the time needed for photovoltaics to become popular is several decades away, according to the author, short-range applications are given. (Author/SA)

  2. Photovoltaics industry profile

    SciTech Connect

    1980-10-01

    A description of the status of the US photovoltaics industry is given. Principal end-user industries are identified, domestic and foreign market trends are discussed, and industry-organized and US government-organized trade promotion events are listed. Trade associations and trade journals are listed, and a photovoltaic product manufacturers list is included. (WHK)

  3. Characterization of Photovoltaic Generators

    ERIC Educational Resources Information Center

    Boitier, V.; Cressault, Y.

    2011-01-01

    This paper discusses photovoltaic panel systems and reviews their electrical properties and use in several industrial fields. We explain how different photovoltaic panels may be characterized by undergraduate students at university using simple methods to retrieve their electrical properties (power, current and voltage) and compare these values…

  4. Solar Photovoltaic Cells.

    ERIC Educational Resources Information Center

    Mickey, Charles D.

    1981-01-01

    Reviews information on solar radiation as an energy source. Discusses these topics: the key photovoltaic material; the bank theory of solids; conductors, semiconductors, and insulators; impurity semiconductors; solid-state photovoltaic cell operation; limitations on solar cell efficiency; silicon solar cells; cadmium sulfide/copper (I) sulfide…

  5. Microsystems Enabled Photovoltaics

    ScienceCinema

    Gupta, Vipin; Nielson, Greg; Okandan, Murat, Granata, Jennifer; Nelson, Jeff; Haney, Mike; Cruz-Campa, Jose Luiz

    2014-06-23

    Sandia's microsystems enabled photovoltaic advances combine mature technology and tools currently used in microsystem production with groundbreaking advances in photovoltaics cell design, decreasing production and system costs while improving energy conversion efficiency. The technology has potential applications in buildings, houses, clothing, portable electronics, vehicles, and other contoured structures.

  6. Handbook for photovoltaic cabling

    SciTech Connect

    Klein, D. N.

    1980-08-01

    This volume, originally written as part of the Interim Performance Criteria Document Development Implementation Plan and Procedures for Photovoltaic Energy Systems, is an analysis of the several factors to be considered in selecting cabling for photovoltaic purposes. These factors, correspoonding to chapter titles, are electrical, structural, safety, durability/reliability, and installation. A glossary of terms used within the volume is included for reference.

  7. Microsystems Enabled Photovoltaics

    SciTech Connect

    Gupta, Vipin; Nielson, Greg; Okandan, Murat, Granata, Jennifer; Nelson, Jeff; Haney, Mike; Cruz-Campa, Jose Luiz

    2012-07-02

    Sandia's microsystems enabled photovoltaic advances combine mature technology and tools currently used in microsystem production with groundbreaking advances in photovoltaics cell design, decreasing production and system costs while improving energy conversion efficiency. The technology has potential applications in buildings, houses, clothing, portable electronics, vehicles, and other contoured structures.

  8. The effects of intragastric infusion of umami solutions on amygdalar and lateral hypothalamic neurons in rats

    PubMed Central

    Davaasuren, Munkhzul; Matsumoto, Jumpei; Chinzorig, Choijiljav; Nakamura, Tomoya; Takamura, Yusaku; Patrono, Enrico; Kondoh, Takashi; Ono, Taketoshi; Nishijo, Hisao

    2015-01-01

    Previous behavioral studies have suggested that l-glutamate, an umami substance, is detected in the gut, and that this information regarding glutamate is conveyed from the gut to the amygdala and the lateral hypothalamus (LH) through the vagus nerve to establish glutamate preference. In this study, we investigated the roles of the amygdala and LH in the information processing of gut glutamate. We recorded the activity of amygdalar and LH neurons during the intragastric administration of five test solutions (monosodium l-glutamate [MSG, 60 mmol/L]; inosine monophosphate [IMP, 60 mmol/L]; a mixture of MSG and IMP; NaCl [60 mmol/L]; or physiological saline) in intact and subdiaphragmatic vagotomized awake rats. In intact rats, 349 and 189 neurons were recorded from the amygdala and LH, respectively, while in vagotomized rats, 104 and 90 neurons were recorded from the amygdala and LH, respectively. In intact rats, similar percentages of neurons (30–60%) in the amygdala and LH responded to the intragastric infusion of the solutions. Vagotomy significantly altered responses to the MSG and NaCl solutions. In particular, vagotomy suppressed the inhibitory responses to the NaCl solution. Furthermore, vagotomy increased the response similarity between the MSG and NaCl solutions, suggesting that vagotomy impaired the coding of the postingestive consequences of the MSG solution in the amygdala and LH, which are unique for glutamate. The present results provide the first neurophysiological evidence that amygdalar and LH neurons process glutamate signals from the gut. PMID:26438732

  9. The effects of intragastric infusion of umami solutions on amygdalar and lateral hypothalamic neurons in rats.

    PubMed

    Davaasuren, Munkhzul; Matsumoto, Jumpei; Chinzorig, Choijiljav; Nakamura, Tomoya; Takamura, Yusaku; Patrono, Enrico; Kondoh, Takashi; Ono, Taketoshi; Nishijo, Hisao

    2015-10-01

    Previous behavioral studies have suggested that l-glutamate, an umami substance, is detected in the gut, and that this information regarding glutamate is conveyed from the gut to the amygdala and the lateral hypothalamus (LH) through the vagus nerve to establish glutamate preference. In this study, we investigated the roles of the amygdala and LH in the information processing of gut glutamate. We recorded the activity of amygdalar and LH neurons during the intragastric administration of five test solutions (monosodium l-glutamate [MSG, 60 mmol/L]; inosine monophosphate [IMP, 60 mmol/L]; a mixture of MSG and IMP; NaCl [60 mmol/L]; or physiological saline) in intact and subdiaphragmatic vagotomized awake rats. In intact rats, 349 and 189 neurons were recorded from the amygdala and LH, respectively, while in vagotomized rats, 104 and 90 neurons were recorded from the amygdala and LH, respectively. In intact rats, similar percentages of neurons (30-60%) in the amygdala and LH responded to the intragastric infusion of the solutions. Vagotomy significantly altered responses to the MSG and NaCl solutions. In particular, vagotomy suppressed the inhibitory responses to the NaCl solution. Furthermore, vagotomy increased the response similarity between the MSG and NaCl solutions, suggesting that vagotomy impaired the coding of the postingestive consequences of the MSG solution in the amygdala and LH, which are unique for glutamate. The present results provide the first neurophysiological evidence that amygdalar and LH neurons process glutamate signals from the gut. PMID:26438732

  10. Cognition and eating behavior in amyotrophic lateral sclerosis: effect on survival.

    PubMed

    Ahmed, R M; Caga, J; Devenney, E; Hsieh, S; Bartley, L; Highton-Williamson, E; Ramsey, E; Zoing, M; Halliday, G M; Piguet, O; Hodges, J R; Kiernan, M C

    2016-08-01

    It is increasingly recognized that metabolic factors influenced by eating behavior, may affect disease progression in neurodegeneration. In frontotemporal dementia (FTD), which shares a significant overlap with Amyotrophic lateral sclerosis (ALS), patients are well known to develop changes in eating behavior. Whether patients with pure ALS and those with cognitive and behavioral changes associated with ALS also develop similar changes is not known. The current study aimed to examine caloric intake, eating behavioral changes, body mass index, and using cox regression analyses survival across the spectrum of 118 ALS-FTD patients (29 pure ALS, 12 ALS-plus and 21 ALS-FTD, 56 behavioral variant FTD), compared with 25 control subjects. The current study found contrary to previous assumptions eating changes are not restricted to FTD, but a spectrum of eating behavioral changes occur in ALS, present in those with pure ALS and worsening as patients develop cognitive changes. ALS patients with cognitive impairment exhibited changes in food preference, with caloric intake and BMI increasing with the development of cognitive/behavioral changes. Both pure ALS and those with cognitive impairment demonstrated increased saturated fat intake. Survival analyses over the mean patient follow-up period of 6.9 years indicated that increasing eating behavioral changes were associated with an improved survival (threefold decrease risk of dying). Changes in eating behavior and metabolism occur in ALS in association with increasing cognitive impairment, perhaps exerting a protective survival influence. These changes provide insights into the common neural networks controlling eating and metabolism in FTD and ALS and provide potential targets to modify disease prognosis and progression. PMID:27260291

  11. Driver perception of roadside configurations on two-lane rural roads: Effects on speed and lateral placement.

    PubMed

    Bella, Francesco

    2013-01-01

    This paper reports the results of a driving simulator study which sought to analyze the effect that: (a) three roadside configurations on a two-lane rural road lined with trees have on speed and lateral position of the driver, depending on different cross-sections as well as geometric elements; (b) the beginning of the guardrail barrier has upon the driver's behavior whenever this occurs on the left curve, right curve or tangent. A two-lane rural road lined with trees was designed and implemented in an advanced-interactive driving simulator. Two different cross-sections (with and without a shoulder), which were combined with three roadside configurations (only trees, trees and barriers, trees and barriers having undergone a treatment), were tested. Six road scenarios were then analyzed. Thirty-six drivers (33 were deemed to be valid and used for the analysis) drove in the simulator using these scenarios and the speed and lateral placement values were collected. Statistical analysis showed that the driver behavior was only affected by the cross-sections and geometric elements but not by roadside configurations. Although the presence of trees along the road represents a factor that increases the severity of run-off-road accidents, drivers do not change their behavior when barriers are not present. Concerning the effects of the beginning of the barrier, MANOVA revealed a main effect for roadside configuration on lateral position but not on speed. There was also a clear tendency of drivers to "cut" both the right curves as well as the left curves in order to minimize the speed reduction in the tangent-curve-tangent transition. These main results allow useful suggestions to be made as regards safety measures for improving road safety on two-lane rural roads lined with trees. PMID:22595299

  12. Interdigitated photovoltaic power conversion device

    DOEpatents

    Ward, J.S.; Wanlass, M.W.; Gessert, T.A.

    1999-04-27

    A photovoltaic power conversion device has a top surface adapted to receive impinging radiation. The device includes at least two adjacent, serially connected cells. Each cell includes a semi-insulating substrate and a lateral conductivity layer of a first doped electrical conductivity disposed on the substrate. A base layer is disposed on the lateral conductivity layer and has the same electrical charge conductivity thereof. An emitter layer of a second doped electrical conductivity of opposite electrical charge is disposed on the base layer and forms a p-n junction therebetween. A plurality of spaced channels are formed in the emitter and base layers to expose the lateral conductivity layer at the bottoms thereof. A front contact grid is positioned on the top surface of the emitter layer of each cell. A first current collector is positioned along one outside edge of at least one first cell. A back contact grid is positioned in the channels at the top surface of the device for engagement with the lateral conductivity layer. A second current collector is positioned along at least one outside edge of at least one oppositely disposed second cell. Finally, an interdigitation mechanism is provided for serially connecting the front contact grid of one cell to the back contact grid of an adjacent cell at the top surface of the device. 15 figs.

  13. Interdigitated photovoltaic power conversion device

    DOEpatents

    Ward, James Scott; Wanlass, Mark Woodbury; Gessert, Timothy Arthur

    1999-01-01

    A photovoltaic power conversion device has a top surface adapted to receive impinging radiation. The device includes at least two adjacent, serially connected cells. Each cell includes a semi-insulating substrate and a lateral conductivity layer of a first doped electrical conductivity disposed on the substrate. A base layer is disposed on the lateral conductivity layer and has the same electrical charge conductivity thereof. An emitter layer of a second doped electrical conductivity of opposite electrical charge is disposed on the base layer and forms a p-n junction therebetween. A plurality of spaced channels are formed in the emitter and base layers to expose the lateral conductivity layer at the bottoms thereof. A front contact grid is positioned on the top surface of the emitter layer of each cell. A first current collector is positioned along one outside edge of at least one first cell. A back contact grid is positioned in the channels at the top surface of the device for engagement with the lateral conductivity layer. A second current collector is positioned along at least one outside edge of at least one oppositely disposed second cell. Finally, an interdigitation mechanism is provided for serially connecting the front contact grid of one cell to the back contact grid of an adjacent cell at the top surface of the device.

  14. Photovoltaic multiplicities

    NASA Astrophysics Data System (ADS)

    Queisser, Hans J.

    1997-04-01

    A multicell solar energy converter, produced in 1959/60 at the Shockley Transistor Corporation, is reviewed. The feasibility of this device, one of the first involving principles of Si integrated circuits, was demonstrated in anticipation of large-area Si sheets, to be pulled from Si/Pb binary melts. Secondly, the generation of multiple carrier pairs by absorption of merely one photon is discussed. Experiments on high-quality Si solar cells demonstrated this effect, which relies on inverse Auger generation. In principle, much higher maximal conversion efficiencies would be possible; novel criteria for materials optimization result. The new challenge of the inverse band structure problem arises. Finally, multistage optical transitions via deep centers in solar cells are briefly appraised.

  15. Second-meal effects of pulses on blood glucose and subjective appetite following a standardized meal 2 h later.

    PubMed

    Mollard, Rebecca C; Wong, Christina L; Luhovyy, Bohdan L; Cho, France; Anderson, G Harvey

    2014-07-01

    This study investigated whether pulses (chickpeas, yellow peas, navy beans, lentils) have an effect on blood glucose (BG) and appetite following a fixed-size meal 2 h later. Over the following 2 h, all pulses lowered BG area under the curve (AUC) and lentils reduced appetite AUC compared with white bread (p < 0.05). Following the meal, BG was lower after lentils and chickpeas at 150 and 165 min, and AUC was lower after lentils compared with white bread (p < 0.05). PMID:24797207

  16. Charts and approximate formulas for the estimation of aeroelastic effects of the lateral control of swept and unswept wings

    NASA Technical Reports Server (NTRS)

    Foss, Kenneth A; Diederich, Franklin W

    1953-01-01

    Charts and approximate formulas are presented for the estimation of static aeroelastic effects on the spanwise lift distribution, rolling-moment coefficient, and rate of roll due to the deflection of ailerons on swept and unswept wings at subsonic and supersonic speeds. Some design considerations brought out by the results of this report are discussed. This report treats the lateral-control case in a manner similar to that employed in NACA Report 1140 for the symmetric-flight case, and is intended to be used in conjunction with NACA Report 1140 and the charts and formulas presented therein.

  17. Basic research challenges in crystalline silicon photovoltaics

    SciTech Connect

    Werner, J.H.

    1995-08-01

    Silicon is abundant, non-toxic and has an ideal band gap for photovoltaic energy conversion. Experimental world record cells of 24 % conversion efficiency with around 300 {mu}m thickness are only 4 % (absolute) efficiency points below the theoretical Auger recombination-limit of around 28 %. Compared with other photovoltaic materials, crystalline silicon has only very few disadvantages. The handicap of weak light absorbance may be mastered by clever optical designs. Single crystalline cells of only 48 {mu}m thickness showed 17.3 % efficiency even without backside reflectors. A technology of solar cells from polycrystalline Si films on foreign substrates arises at the horizon. However, the disadvantageous, strong activity of grain boundaries in Si could be an insurmountable hurdle for a cost-effective, terrestrial photovoltaics based on polycrystalline Si on foreign substrates. This talk discusses some basic research challenges related to a Si based photovoltaics.

  18. Vagus nerve stimulation…25 years later! What do we know about the effects on cognition?

    PubMed

    Vonck, Kristl; Raedt, Robrecht; Naulaerts, Joke; De Vogelaere, Frederick; Thiery, Evert; Van Roost, Dirk; Aldenkamp, Bert; Miatton, Marijke; Boon, Paul

    2014-09-01

    VNS therapy was delivered to patients for the first time in 1988. After 25 years, insight in the antiepileptic and antidepressant mechanism of action of VNS has grown steadily. The effects on cognition and especially memory remain controversial. This review provides an elaborate overview of studies addressing cognition and describes potential underlying mechanisms for the reported effects. Short-term VNS has an effect on verbal memory recognition when administered at the correct timing and dosage. Chronic VNS resulted into a positive effect on the cognitive status in an Alzheimer population. Positive effect of chronic VNS in epilepsy or depression patients on global cognitive functioning are less convincing. Neither do the results reveal a negative effect which has major implications for chronic treatment of neurology patients. A cascade of neurochemical processes put in motion by changes in NE concentrations in reaction to stimulation of the vagal nerve may underlie the VNS-induced effects on cognition and memory. In Alzheimer pathology, NE may act as an anti-inflammatory agent on brainstem nuclei. PMID:24858008

  19. Dilution effect of Ar/H2 on the microstructures and photovoltaic properties of nc-Si:H deposited in low frequency inductively coupled plasma

    NASA Astrophysics Data System (ADS)

    Zhou, H. P.; Wei, D. Y.; Xu, S.; Xiao, S. Q.; Xu, L. X.; Huang, S. Y.; Guo, Y. N.; Yan, W. S.; Xu, M.

    2011-07-01

    This work reports upon the dilution effect of Ar + H2 on the microstructures, optical, and photovoltaic properties of the hydrogenated nanocrystalline silicon (nc-Si:H) thin films. High crystallinity (up to 82.6%) nc-Si:H thin films were fabricated from silane diluted by Ar + H2 in a low-frequency inductively coupled plasma (LFICP) facility at a low temperature of 300 °C. The substitution of H2 by Ar in the diluent gas leads to an increase of the deposition rate, grain size, and crystallinity, and a decrease of the optical bandgap. Varying the Ar content caused a fluctuation of the H concentration and a change of the preferential orientation from (111) to (220) in the synthesized thin films. These effects physically originated from changes of the Ar + H2 + SiH4 plasma environment in the LFICP system. The enhancement of the dissociation of SiH4/H2 molecules by ion Ar+ and the metastable state Ar* were discussed in terms of related chemical reactions between the diluent gases and silane. Furthermore, it was found that a heterojunction solar cell prototype based on the as-deposited nc-Si:H thin films exhibits an excellent photovoltaic response.

  20. Polycrystalline thin film photovoltaic technology

    SciTech Connect

    Ullal, H.S.; Zweibel, K.; Mitchell, R.L.; Noufi, R.

    1991-03-01

    Low-cost, high-efficiency thin-film modules are an exciting photovoltaic technology option for generating cost-effective electricity in 1995 and beyond. In this paper we review the significant technical progress made in the following thin films: copper indium diselenide, cadmium telluride, and polycrystalline thin silicon films. Also, the recent US DOE/SERI initiative to commercialize these emerging technologies is discussed. 6 refs., 9 figs.

  1. Orthogonal Thin Film Photovoltaics on Vertical Nanostructures.

    PubMed

    Ahnood, Arman; Zhou, H; Suzuki, Y; Sliz, R; Fabritius, T; Nathan, Arokia; Amaratunga, G A J

    2015-12-01

    Decoupling paths of carrier collection and illumination within photovoltaic devices is one promising approach for improving their efficiency by simultaneously increasing light absorption and carrier collection efficiency. Orthogonal photovoltaic devices are core-shell type structures consisting of thin film photovoltaic stack on vertical nanopillar scaffolds. These types of devices allow charge collection to take place in the radial direction, perpendicular to the path of light in the vertical direction. This approach addresses the inherently high recombination rate of disordered thin films, by allowing semiconductor films with minimal thicknesses to be used in photovoltaic devices, without performance degradation associated with incomplete light absorption. This work considers effects which influence the performance of orthogonal photovoltaic devices. Illumination non-uniformity as light travels across the depth of the pillars, electric field enhancement due to the nanoscale size and shape of the pillars, and series resistance due to the additional surface structure created through the use of pillars are considered. All of these effects influence the operation of orthogonal solar cells and should be considered in the design of vertically nanostructured orthogonal photovoltaics. PMID:26676997

  2. Orthogonal Thin Film Photovoltaics on Vertical Nanostructures

    NASA Astrophysics Data System (ADS)

    Ahnood, Arman; Zhou, H.; Suzuki, Y.; Sliz, R.; Fabritius, T.; Nathan, Arokia; Amaratunga, G. A. J.

    2015-12-01

    Decoupling paths of carrier collection and illumination within photovoltaic devices is one promising approach for improving their efficiency by simultaneously increasing light absorption and carrier collection efficiency. Orthogonal photovoltaic devices are core-shell type structures consisting of thin film photovoltaic stack on vertical nanopillar scaffolds. These types of devices allow charge collection to take place in the radial direction, perpendicular to the path of light in the vertical direction. This approach addresses the inherently high recombination rate of disordered thin films, by allowing semiconductor films with minimal thicknesses to be used in photovoltaic devices, without performance degradation associated with incomplete light absorption. This work considers effects which influence the performance of orthogonal photovoltaic devices. Illumination non-uniformity as light travels across the depth of the pillars, electric field enhancement due to the nanoscale size and shape of the pillars, and series resistance due to the additional surface structure created through the use of pillars are considered. All of these effects influence the operation of orthogonal solar cells and should be considered in the design of vertically nanostructured orthogonal photovoltaics.

  3. Nonlinearity Effects of Lateral Density Diffusion Coefficient on Gain-Guided VCSEL Performance

    NASA Technical Reports Server (NTRS)

    Li, Jian-Zhong; Cheung, Samson H.; Ning, C. Z.; Biegel, Bryan (Technical Monitor)

    2001-01-01

    Electron and hole diffusions in the plane of semiconductor quantum wells play an important part in the static and dynamic operations of semiconductor lasers. In this paper, we apply a hydrodynamic model developed from the semiconductor Bloch equations to numerically study the effects of nonlinearity in the diffusion coefficient on single mode operation and direct modulation of a gain-guided InGaAs/GaAs multiple quantum well laser, operating not too far from threshold. We found that a small diffusion coefficient is advantageous for lowering the threshold current and increasing the modulation bandwidth. Most importantly, the effects of nonlinearity in the coefficient can be approximately reproduced by replacing the coefficient with an effective constant diffusion coefficient, which corresponds roughly to the half height density of the density distribution.

  4. Geometric size effect on the extrinsic Gilbert damping in laterally confined magnetic structures

    NASA Astrophysics Data System (ADS)

    Song, Hyon-Seok; Lee, Kyeong-Dong; You, Chun-Yeol; Park, Byong-Guk; Hong, Jung-Il

    2016-05-01

    We investigated spin dynamics in micron-length scale patterned thin films using the GPU-based micromagnetic simulation program. Spin precessional motion was induced by a Gaussian-pulse magnetic field. The effective Gilbert damping was examined by tracking the precessional motion of the spins, and we found that the damping constant depends on the size and shape of the pattern as well as the externally applied magnetic field. Additional extrinsic damping generated around the edge region was attributed to the dephasing effect between the fundamental spin wave and other spin wave modes. We find that the effect of extrinsic damping could be eliminated by proper adjustments of sample size, external bias field, position, and area of observation.

  5. The effect of early-life education on later-life mortality.

    PubMed

    Black, Dan A; Hsu, Yu-Chieh; Taylor, Lowell J

    2015-12-01

    Many studies link cross-state variation in compulsory schooling laws to early-life educational attainment, thereby providing a plausible way to investigate the causal impact of education on various lifetime outcomes. We use this strategy to estimate the effect of education on older-age mortality of individuals born in the early twentieth century U.S. Our key innovation is to combine U.S. Census data and the complete Vital Statistics records to form precise mortality estimates by sex, birth cohort, and birth state. In turn we find that virtually all of the variation in these mortality rates is captured by cohort effects and state effects alone, making it impossible to reliably tease out any additional impact due to changing educational attainment induced by state-level changes in compulsory schooling. PMID:26340596

  6. The effect of landing system coverage and path geometry on lateral position errors at the runway threshold

    NASA Technical Reports Server (NTRS)

    Vicroy, D. D.

    1978-01-01

    The results of an analytical study performed to determine the effect of the azimuth coverage of a Microwave Landing System (MLS) on the ability of an airplane, with an initial navigation position estimate error, to navigate to the runway threshold are presented. The test path chosen for this study consists of an initial straight segment leading into a 130 deg turn with a 2286 m radius and ending in a straight-in final approach segment. The test path configuration was varied by changing the MLS azimuth coverage angle and the final approach length. The aircraft was positioned with an inital offset to the left or right of the desired path along the line of intersection with the MLS azimuth coverage. A fast time computer simulation program, using a simplistic point mass model of the airplane, was used for this study. The data from this study indicates that the lateral position errors at the runway are primarily a function of the final approach length. The effect of the azimuth coverage on the lateral position errors was restricted by the turn characteristics of the horizontal steering control laws.

  7. Lateralization effects of image-guided 31P magnetoresonance spectroscopic parameters in the frontal lobe of schizophrenics and healthy controls

    NASA Astrophysics Data System (ADS)

    Huebner, Gabriele; Volz, Hans-Peter; Riehemann, Stefan; Wenda, Berit; Roessger, Grit; Rzanny, Reinhard; Sauer, Heinrich

    1999-05-01

    Phosphorus-31 magnetic resonance spectroscopy (31P-MRS) has gained much interest in schizophrenia research in the last years since it allows the non-invasive measurement of high- energy phosphates and phospholipids in vivo. We investigated hemispherical differences of the concentrations of different phosphorus compounds in the frontal lobes. For this purpose, well defined volumes in the dorsolateral prefrontal cortex of 32 healthy controls and 51 schizophrenic patients were examined. Schizophrenic patients showed significant lateralization effects of phosphodiesters (PDE) and the intracellular pH-value. Differences in the lateralization of 31P-MRS parameters between patients and healthy volunteers were only detected for the pH-value. While healthy controls exhibit lower pH-values in the left frontal lobe (6.96), in schizophrenic patients we found lower pH-values in the right (6.89). Detailed examinations showed that this effect is mainly based on the subgroup of schizophrenics who received atypical neuroleptic medication.

  8. Resonant plasmonic terahertz detection in graphene split-gate field-effect transistors with lateral p–n junctions

    NASA Astrophysics Data System (ADS)

    Ryzhii, V.; Ryzhii, M.; Shur, M. S.; Mitin, V.; Satou, A.; Otsuji, T.

    2016-08-01

    We evaluate the proposed resonant terahertz (THz) detectors on the basis of field-effect transistors (FETs) with split gates, electrically induced lateral p–n junctions, uniform graphene layer (GL) or perforated (in the p–n junction depletion region) graphene layer (PGL) channel. The perforated depletion region forms an array of the nanoconstions or nanoribbons creating the barriers for the holes and electrons. The operation of the GL-FET- and PGL-FET-detectors is associated with the rectification of the ac current across the lateral p–n junction enhanced by the excitation of bound plasmonic oscillations in the p- and n-sections of the channel. Using the developed device model, we find the GL-FET- and PGL-FET-detector characteristics. These detectors can exhibit very high voltage responsivity at the THz radiation frequencies close to the frequencies of the plasmonic resonances. These frequencies can be effectively voltage tuned. We show that in PL-FET-detectors the dominant mechanism of the current rectification is due to the tunneling nonlinearity, whereas in the PGL-FET-detector the current rectification is primarily associated with the thermionic processes. Due to much lower p–n junction conductance in the PGL-FET-detectors, their resonant response can be substantially more pronounced than in the GL-FET-detectors corresponding to fairly high detector responsivity.

  9. WWC Quick Review of the Article "Effects of Social Development Intervention in Childhood 15 Years Later"

    ERIC Educational Resources Information Center

    What Works Clearinghouse, 2009

    2009-01-01

    The selected study examined the long-term effects of the "Seattle Social Development Project (SSDP)," an elementary-school-based intervention designed to improve students' social skills and engagement. The study analyzed data on about 600 young adults who had been students in 15 public elementary schools serving high-crime areas in Seattle,…

  10. Racial/Ethnic Differences in Effects of Welfare Policies on Early School Readiness and Later Achievement

    ERIC Educational Resources Information Center

    Yoshikawa, Hirokazu; Gassman-Pines, Anna; Morris, Pamela A.; Gennetian, Lisa A.; Godfrey, Erin B.

    2010-01-01

    This study examined whether the effects of employment-based policies on children's math and reading achievement differed for African American, Latino and Caucasian children of welfare receiving parents, and if so, why. Two kinds of employment policies were examined: "education-first" programs with an emphasis on adult education and job training;…

  11. Support for Lateralization of the Whorf Effect beyond the Realm of Color Discrimination

    ERIC Educational Resources Information Center

    Gilbert, Aubrey L.; Regier, Terry; Kay, Paul; Ivry, Richard B.

    2008-01-01

    Recent work has shown that Whorf effects of language on color discrimination are stronger in the right visual field than in the left. Here we show that this phenomenon is not limited to color: The perception of animal figures (cats and dogs) was more strongly affected by linguistic categories for stimuli presented to the right visual field than…

  12. Effect of vision and stance width on human body motion when standing: implications for afferent control of lateral sway.

    PubMed Central

    Day, B L; Steiger, M J; Thompson, P D; Marsden, C D

    1993-01-01

    1. Measurements of human upright body movements in three dimensions have been made on thirty-five male subjects attempting to stand still with various stance widths and with eyes closed or open. Body motion was inferred from movements of eight markers fixed to specific sites on the body from the shoulders to the ankles. Motion of these markers was recorded together with motion of the point of application of the resultant of the ground reaction forces (centre of pressure). 2. The speed of the body (average from eight sites) was increased by closing the eyes or narrowing the stance width and there was an interaction between these two factors such that vision reduced body speed more effectively when the feet were closer together. Similar relationships were found for components of velocity both in the frontal and sagittal planes although stance width exerted a much greater influence on the lateral velocity component. 3. Fluctuations in position of the body were also increased by eye closure or narrowing of stance width. Again, the effect of stance width was more potent for lateral than for anteroposterior movements. In contrast to the velocity measurements, there was no interaction between vision and stance width. 4. There was a progressive increase in the amplitude of position and velocity fluctuations from markers placed higher on the body. The fluctuations in the position of the centre of pressure were similar in magnitude to those of the markers placed near the hip. The fluctuations in velocity of centre of pressure, however, were greater than of any site on the body. 5. Analysis of the amplitude of angular motion between adjacent straight line segments joining the markers suggests that the inverted pendulum model of body sway is incomplete. Motion about the ankle joint was dominant only for lateral movement in the frontal plane with narrow stance widths (< 8 cm). For all other conditions most angular motion occurred between the trunk and leg. 6. The large

  13. Wind effects on the lateral structure of density-driven circulation in Chesapeake Bay

    NASA Astrophysics Data System (ADS)

    Guo, Xinyu; Valle-Levinson, Arnoldo

    2008-10-01

    The response of the density-driven circulation in the Chesapeake Bay to wind forcing was studied with numerical experiments. A model of the bay with realistic bathymetry was first applied to produce the density-driven flow under average river discharge and tidal forcing. Subsequently, four spatially uniform wind fields (northeasterly, northwesterly, southwesterly, and southeasterly) were imposed to examine the resulting cross-estuary structure of salinity and flow fields. In general, northeasterly and northwesterly winds intensified the density-driven circulation in the upper and middle reaches of the bay, whereas southeasterly and southwesterly winds weakened it. The response was different in the lower bay, where downwind flow from the upper and middle reaches of the bay competed with onshore/offshore coastal flows. Wind remote effects were dominant, over local effects, on volume transports through the bay entrance. However, local effects were more influential in establishing the sea-level slopes that drove subtidal flows and salinity fields in most of the bay. The effect of vertical stratification on wind-induced flows was also investigated by switching it off. The absence of stratification allowed development of Ekman layers that reached depths of the same order as the water depth. Consequently, bathymetric effects became influential on the homogeneous flow structure causing the wind-induced flow inside the bay to show a marked transverse structure: downwind over the shallow areas and upwind in the channels. In the presence of stratification, Ekman layers became shallower and the wind-induced currents showed weaker transverse structure than those that developed in the absence of stratification. In essence, the wind-driven flows were horizontally sheared under weak stratification and vertically sheared under stratified conditions.

  14. Polyethylenimine Interfacial Layers in Inverted Organic Photovoltaic Devices: Effects of Ethoxylation and Molecular Weight on Efficiency and Temporal Stability.

    PubMed

    Courtright, Brett A E; Jenekhe, Samson A

    2015-12-01

    We report a comparative study of polyethylenimine (PEI) and ethoxylated-polyethylenimine (PEIE) cathode buffer layers in high performance inverted organic photovoltaic devices. The work function of the indium-tin oxide (ITO)/zinc oxide (ZnO) cathode was reduced substantially (Δφ = 0.73-1.09 eV) as the molecular weight of PEI was varied from 800 g mol(-1) to 750 000 g mol(-1) compared with the observed much smaller reduction when using a PEIE thin film (Δφ = 0.56 eV). The reference inverted polymer solar cells based on the small band gap polymer PBDTT-FTTE (ITO/ZnO/PBDTT-FTTE:PC70BM/MoO3/Ag), without a cathode buffer layer, had an average power conversion efficiency (PCE) of 6.06 ± 0.22%. Incorporation of a PEIE cathode buffer layer in the same PBDTT-FTTE:PC70BM blend devices gave an enhanced performance with a PCE of 7.37 ± 0.53%. In contrast, an even greater photovoltaic efficiency with a PCE of 8.22 ± 0.10% was obtained in similar PBDTT-FTTE:PC70BM blend solar cells containing a PEI cathode buffer layer. The temporal stability of the inverted polymer solar cells was found to increase with increasing molecular weight of the cathode buffer layer. The results show that PEI is superior to PEIE as a cathode buffer layer in high performance organic photovoltaic devices and that the highest molecular weight PEI interlayer provides the highest temporal stability. PMID:26550983

  15. Effects of Head Start REDI on children's outcomes 1 year later in different kindergarten contexts.

    PubMed

    Bierman, Karen L; Nix, Robert L; Heinrichs, Brenda S; Domitrovich, Celene E; Gest, Scott D; Welsh, Janet A; Gill, Sukhdeep

    2014-01-01

    One year after participating in the Research-based, Developmentally Informed (REDI) intervention or "usual practice" Head Start, the learning and behavioral outcomes of 356 children (17% Hispanic, 25% African American; 54% girls; Mage  = 4.59 years at initial assessment) were assessed. In addition, their 202 kindergarten classrooms were evaluated on quality of teacher-student interactions, emphasis on reading instruction, and school-level student achievement. Hierarchical linear analyses revealed that the REDI intervention promoted kindergarten phonemic decoding skills, learning engagement, and competent social problem-solving skills, and reduced aggressive-disruptive behavior. Intervention effects on social competence and inattention were moderated by kindergarten context, with effects strongest when children entered schools with low student achievement. Implications are discussed for developmental models of school readiness and early educational programs. PMID:23647355

  16. Giant photovoltaic effects driven by residual polar field within unit-cell-scale LaAlO3 films on SrTiO3

    PubMed Central

    Liang, Haixing; Cheng, Long; Zhai, Xiaofang; Pan, Nan; Guo, Hongli; Zhao, Jin; Zhang, Hui; Li, Lin; Zhang, Xiaoqiang; Wang, Xiaoping; Zeng, Changgan; Zhang, Zhenyu; Hou, J. G.

    2013-01-01

    For polar/nonpolar heterostructures, Maxwell's theory dictates that the electric potential in the polar components will increase divergently with the film thickness. For LaAlO3/SrTiO3, a conceptually intriguing route, termed charge reconstruction, has been proposed to avert such “polar catastrophe”. The existence of a polar potential in LaAlO3 is a prerequisite for the validity of the charge reconstruction picture, yet to date, its direct measurement remains a major challenge. Here we establish unambiguously the existence of the residual polar potential in ultrathin LaAlO3 films on SrTiO3, using a novel photovoltaic device design as an effective probe. The measured lower bound of the residual polar potential is 1.0 V. Such a direct observation of the giant residual polar potential within the unit-cell-scale LaAlO3 films amounts to a definitive experimental evidence for the charge reconstruction picture, and also points to new technological significance of oxide heterostructures in photovoltaic and sensing devices with atomic-scale control. PMID:23756918

  17. Effects of pentacene-doped PEDOT:PSS as a hole-conducting layer on the performance characteristics of polymer photovoltaic cells.

    PubMed

    Kim, Hyunsoo; Lee, Jungrae; Ok, Sunseong; Choe, Youngson

    2012-01-01

    We have investigated the effect of pentacene-doped poly(3,4-ethylenedioxythiophene:poly(4-styrenesulfonate) [PEDOT:PSS] films as a hole-conducting layer on the performance of polymer photovoltaic cells. By increasing the amount of pentacene and the annealing temperature of pentacene-doped PEDOT:PSS layer, the changes of performance characteristics were evaluated. Pentacene-doped PEDOT:PSS thin films were prepared by dissolving pentacene in 1-methyl-2-pyrrolidinone solvent and mixing with PEDOT:PSS. As the amount of pentacene in the PEDOT:PSS solution was increased, UV-visible transmittance also increased dramatically. By increasing the amount of pentacene in PEDOT:PSS films, dramatic decreases in both the work function and surface resistance were observed. However, the work function and surface resistance began to sharply increase above the doping amount of pentacene at 7.7 and 9.9 mg, respectively. As the annealing temperature was increased, the surface roughness of pentacene-doped PEDOT:PSS films also increased, leading to the formation of PEDOT:PSS aggregates. The films of pentacene-doped PEDOT:PSS were characterized by AFM, SEM, UV-visible transmittance, surface analyzer, surface resistance, and photovoltaic response analysis. PMID:22221320

  18. Effects of Nd-doping on optical and photovoltaic properties of barium titanate thin films prepared by sol–gel method

    SciTech Connect

    Jiang, Weihai; Cai, Wei; Lin, Zebin; Fu, Chunlin

    2013-09-01

    Graphical abstract: - Highlights: • We prepared Nd-doped BTO thin films by sol–gel method. • Addition of Nd to some extent can inhibit the grain growth. • Addition of Nd{sup 3+} ions can decrease band gap. • The remnant polarization of Nd-doped BTO thin films begins to increase and then decreases. • Photovoltaic properties of Nd-doped BTO thin films begin to increase then decrease. - Abstract: Nd-doped barium titanate thin films were prepared via sol–gel spin-coating method and effects of Nd content on microstructure, optical and photovoltaic properties have been investigated. The results show that Nd-doped barium titanate thin films are single tetragonal perovskite phase. Addition of neodymium to some extent can inhibit the grain growth. Substitution of Nd{sup 3+} ions for Ba{sup 2+} on A sites leads to the decrease of band gap. The remnant polarization begins to increase and reach the maximum and then decreases as Nd content increases. The short circuit photocurrent density, open circuit photovoltage and power conversion efficiency of Nd-doped barium titanate thin films begin to increase and reach the maximum and then decrease as Nd content increases.

  19. Photovoltaic/thermal hybrid projects

    NASA Astrophysics Data System (ADS)

    Kush, E. A.

    1980-03-01

    Systems which utilize a combination of photovoltaic and thermal collection in the same solar collectors (PV/T Systems) can have advantages over PV or thermal only systems in that the cost effectiveness of the collectors and their support structure may be improved, active cooling may allow the cells to run at lower temperatures-hence higher conversion efficiency, and space limitations on side by side collectors can be avoided. Evaluation of such systems requires formulation and assessment of collector concepts, power conditioning, storage, and control strategies, and their interactions when combined into a total system. Systems with flat plate PV/T collectors and vapor compression heat pump driven by the photovoltaic electric output are considered along with PV/T concentrating collectors and their potential applications, particularly to solar driven absorption chillers.

  20. The analysis of temperature programmed desorption experiments of systems with lateral interactions; implications of the compensation effect

    NASA Astrophysics Data System (ADS)

    Nieskens, D. L. S.; van Bavel, A. P.; Niemantsverdriet, J. W.

    2003-12-01

    In this paper we have investigated problems that arise when analyzing TPD spectra of desorption processes in which lateral interactions between adsorbed species are present. Dynamic Monte Carlo (DMC) simulations are used to simulate the effect of adsorbate interactions on TPD spectra and we applied the most common methods to derive the activation energy and the pre-exponential factor. The extraction of the kinetic parameters in the zero-coverage limit works well for all methods. The extraction of the coverage dependent values on the other hand is quite difficult since a 'forced' compensation effect can occur, leading to false values for the pre-exponential factor as well as false values for the activation energy. Finally, we suggest a new approach that can be used to estimate the activation energy over the entire coverage range.